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Kisspeptin (formerly known as metastin) is a protein that is encoded by the KISS1 gene in humans. Kisspeptin is a G-protein coupled receptor ligand for GPR54.^[1] Kiss1 was originally identified as a human metastasis suppressor gene that has the ability to suppress melanoma and breast cancer metastasis.^[2] Kisspeptin-GPR54 signaling has an important role in initiating secretion of gonadotropin-releasing hormone (GnRH) at puberty, the extent of which is an area of ongoing research.^[3] Gonadotropin-releasing hormone is released from the hypothalamus to act on the anterior pituitary triggering the release of luteinizing hormone (LH), and follicle stimulating hormone (FSH). These gonadotropic hormones lead to sexual maturation and gametogenesis. Disrupting GPR54 signaling can cause hypogonadotrophic hypogonadism in rodents and humans. The Kiss1 gene is located on chromosome 1. It is transcribed in the brain, adrenal gland, and pancreas.

History

In 1996, Dr. Danny Welch's lab in Hershey, Pennsylvania isolated a cDNA from a cancer cell that was not able to undergo metastasis after the human chromosome 6 was added to the cell. This gene was named KISS1 because of the location of where it was discovered (Hershey, Pennsylvania, home of Hershey's Kisses). Introduction of this chromosome into the once active cancer cell inhibited it from spreading and the cDNA responsible was taken from that cell. The fact that KISS1 was responsible for this was proved when it was transfected into melanoma cells and yet again, metastasis was suppressed.^[4] Later, a breakthrough would occur not involving Kisspeptin, but with its receptor.

Three years later in 1999, a G protein coupled receptor was identified in rat, cloned, and termed GPR54.^[4] Additionally, two years later, this receptor’s ortholog in humans would be isolated.^[4] Using the identified receptors, endogenous ligands were isolated from cells (HEK293, B16-BL6, and CHO-K1 cells) that had these receptors inserted into them.^[4] The next step in the history of Kisspeptin involved revealing more of its pathways and the mechanism involved.

Kisspeptin was found to play a role in hypogonadotropic hypogonadism in 2003, which was supported by several independent lab groups.^[4] A mutation in GPR54 was considered responsible for this abnormality because those who held this mutation, or were missing GPR54 altogether, had problems in gonadal development during puberty.^[4] Several other phenotypes related to this mutation included a smaller sex steroid and gonadotropin concentration in the circulating blood and even sterility.^[4] These observations prompted the research on how kisspeptin is involved during the beginning of puberty. This research led to the discovery that kisspeptin stimulates the neurons that were involved in the release of gonadotropin-releasing hormone (GnRH) and possibly may have some impact on the release of luteinizing hormone (LH) and follicle-stimulating hormone (FSH).^[4]

Today, much effort is being made to characterize the regulation of kisspeptin and its gene expression, as well as to more specifically determine the mechanism behind kisspeptin's action on GnRH and LH release.^[5]

Sources

Hippocampal dentate gyrus

File:Hypothalamus small.gif

Human hypothalamus (shown in red)

Kisspeptin is most notably expressed in the hypothalamus, but is also found in other areas of the brain including the hippocampal dentate gyrus. The hippocampus is known to integrate information on a person's spatial environment and memory. KISS1 is known to be expressed in the hippocampus. However, the levels of KISS1 mRNA expressed are decidedly lower than in the hypothalamus and amygdala. Studies have shown that the levels of KISS1 mRNA expressed in the hippocampus are proportional to less than half of the levels found in the hypothalamus. Despite this, it is suggested that expression of KISS1 is influenced by the gonad hormones similar to the hypothalamus. There is a high degree of expression of GPR54 in the hippocampus. The density of GPR54 is not discernable in pyramidal cells, but has high levels of expression in the granule cell layer. It is known to be found in specific nuclei and neurons.^[6]

Adrenal gland

The neuropeptide kisspeptin plays an important role in reproduction, but also stimulates aldosterone secretion from the adrenal cortex. Kisspeptin is distributed from the adrenal cortex and it is transcribed in the neocortex. The exact nature of the expression of kisspeptins in human adrenal glands unfortunately has not been fully clarified yet and remains a large topic of research among many scientists.^[7]

Genomics

Kisspeptin is a product of the KISS1 gene which is cleaved from an initial 145 amino acid peptide to a 54 amino acid long protein.^[8] This gene is located on the long arm of chromosome 1 (1q32) and has four exons of which the 5' and 3' exons only partly undergo translation. The KISS1 gene was first isolated as a tumor spreading gene by investigators and named metastin. Metastin is derived from the protein kisspeptin and is a natural ligand of the receptor known as GPR54 Kisspeptin expression in the brain: Catalyst for the initiation of puberty.^[9] Different types made up of 14 and 13 amino acids have been isolated and they each share a common C-terminal sequence. These N-terminally truncated peptides are known as the kisspeptins and belong to a larger family of peptides known as RFamides which all share a common arginine-phenylalanine-NH2 motif at their C-terminus. Among these conserved amino acids are arginine and phenylalanine residues, which are paired in this family of peptides. Also within this conserved family is a C-terminus that has an amide added to it. This family which kisspeptin includes prolactin releasing peptide and gonadotropin releasing inhibiting hormone.^[9]

A polymorphism in the terminal exon of this mRNA results in two protein isoforms. An adenosine present at the polymorphic site represents the third position in a stop codon. When the adenosine is absent, a downstream stop codon is utilized and the encoded protein extends for an additional seven amino acid residues.^[10]

Structure

Kisspeptin

The gene for kisspeptin codes for a peptide that can be cleaved into several pieces.^[5] In humans, one of these pieces is made up of 54 amino acids, while in mice it is made up of 52 amino acids.^[11] This fragment is then proteolytically processed into several smaller fragments that have been isolated in humans composed of 13 and 14 amino acids (kisspeptin-13 and kisspeptin-14 respectively). Each of these fragments has a similar conserved region at the C-terminal sequence consisting of ten amino acids.^[4] Specifically, positions 2, 4, 6, 7, 8, and 9 in this region are completely conserved where any variation seen is due to random mutations. The sequence on the carboxy terminal side of the conserved region is a well-known site for cleavage in neuropeptides.^[4]

GPR54

The structure for GPR54 is very similar throughout many different vertebrates.^[4] It is composed of 398 amino acids that form seven transmembrane domains, like most G-protein coupled receptors. Sequences found in transmembrane spanning regions one, four, and seven are all very highly conserved throughout species. Variation appears in the around the amino and C-terminal domains, which accounts for the different types of Kisspeptin receptors seen in various species.^[4]

Pathway

GnRH release

Kisspeptin-54 interacts with G protein-coupled receptors, specifically GPR54 (Kiss1R). Other versions of kisspeptin are also able to interact with Kiss1R.^[5] Research in both rats and humans has provided evidence that the binding of kisspeptin stimulates PIP2 hydrolysis, Ca²⁺ mobilization, arachidonic acid release, extracellular signal-regulated protein kinase 1 (ERK1), ERK2, and p38 MAP kinase phosphorylation.^[5] Although GnRH is located in many areas such as the pituitary gland and the GnRH neurons, research proves that GnRH is highly dependent upon GnRH neuron activation and less dependent on the pituitary gonadotropes.^[5] Many studies show that kisspeptin has the ability to not only cause depolarization, but also excite many GnRH neurons, leading to high expression of kisspeptin in these genes.^[5] But, it is hypothesized that there are two different types of GFP-GnRH neurons due to expression in some neurons but not others, only one of which responds to kisspeptin.^[5] The neurons response to kisspeptin is also hypothesized to be related to age and puberty.^[5] The binding of kisspeptin to the GnRH receptor can have effects on puberty, tumor suppression and reproduction.

Biological function

Kisspeptin can stimulate secretion of aldosterone and the release of insulin.

Kisspeptin appears to directly activate GnRH neurons. Evidence for this involves the persistence of a neural response to kisspeptin levels even in the presence of TTX, a neurotoxin that blocks nerve signals.

Gramicidin-perforated patch recordings: about 30% of GnRH neurons respond to kisspeptin administration in prepubertal males, whereas 60% of GnRH neurons in adult mice responded.
Because only adult mice respond to low doses of kisspeptin, it appears that GnRH neurons become developmentally activated by kisspeptin over the course of puberty.
Kisspeptin induces production of LH and FSH, which are required for female's menstruation. Athletes may not undergo menstruation due to low fat levels; fat produces the hormone leptin, which induces production of kisspeptin.

Role in puberty

The onset of puberty is marked by an increase in gonadotropin secretion, which leads to sexual maturity and the ability to reproduce. Puberty can also be affected by a range of environmental factors, and is known to be affected by a person's metabolic capacity.^[12] Gonadotropin secretion is brought about and regulated by gonadotropin releasing hormone (GnRH). GnRH leads to the release of luteinizing hormone (LH) and follicle stimulating hormone (FSH), which primarily target the gonads to trigger puberty and reproduction. The primary event that leads to the beginning of puberty is the activation of GnRH neurons. This event is thought to involve kisspeptin/GPR54 signaling, which leads to the eventual activation of GnRH neurons.^[9] Several studies have confirmed that addition of kisspeptin to biological systems including rat, mouse, and sheep are able to bring about the release of LH and FSH. In addition to this, the release of these gonadotropins has proven to be dose dependent. A greater addition of kisspeptin peptide resulted in greater release of LH and FSH. Kisspeptin was found to evoke one of the strongest effects on the gonadotropin system.^[12]

Figure 28 03 01.jpg

Figure 28 03 01

Kisspeptin's ability to stimulate the release of GnRH and gonadotropins is the result of its effect on GnRH release at the hypothalamus. In rat hypothalamus, it was found that over three-fourths of GnRH neurons coexpress the receptor for kisspeptin, GPR54, in their RNA. Kisspeptin was also able to bring about the release of GnRH both ex vivo and in vivo in rat and sheep. It can be concluded that by activating GnRH neurons in the hypothalamus, kisspeptin causes GnRH release which leads to the release of FSH and LH.^[12] The major role kisspeptin/GPR54 plays in sexual development was initially found in sexually immature humans and mice who had mutations that blocked the expression of the GPR54 gene. In rats, the initiation of puberty accompanied a greater presence of KISS1 and GPR54 in mRNA. The same events were later observed in mammals, where KISS1 and GPR54 mRNA increased more than twofold in the hypothalamus. This suggests that there is greater expression of KISS1 and potentially even GPR54 at the onset of puberty leading to an increase in kisspeptin/GPR54 signaling that results in the activation of the gonadotropin pathway.^[12] The addition of kisspeptin to female rats who had yet to mature led to the initiation of gonadotropin pathway. In humans, it was shown that females at the beginning stages of puberty had much higher kisspeptin levels than those females of the same age who had yet to begin puberty. It has been concluded that the activation of the GPR54/kisspeptin pathway is a catalyst that leads to puberty onset.^[12]

Role in tumor suppression

Kisspeptin plays a role in tumor suppression. In a study where malignant tumor cells were injected into a model system, the system was then tested for genes involved in the injected chromosome 6. KISS1 was discovered to be the only gene expressed in non-metastatic cells and absent in metastatic, metastatic meaning the ability for cancer to spread to unconnected areas. This suggested that there Kisspeptin is an essential regulation factor in whether or not a cell will be metastatic or not. Additional experimentation identified CRSP3 as the exact gene responsible for KISS1 regulation within chromosome 6. In clinical evidence studies, KISS1 and Kisspeptin were found in primary, metastatic tumors, and growing tumors showing decreased levels of KISS1 and Kisspeptin.^[8] In conclusion, kisspeptin plays a large role in tumor suppression. When it is active in cells the tumor stays consolidated and does not spread or grow.

Role in reproduction

Kisspeptin is highly expressed during pregnancy. In early-term placentas, GPR54 was expressed at a higher rate than placentas at-term. The expression of kisspeptin, however, remains unchanged in the placenta throughout pregnancy. The increased expression of GPR54 in early-term placentas is due to the increased presence of intrusive trophoblasts during the beginning of pregnancy. Term cells, by comparison are less invasive. When measuring kisspeptin-54 during pregnancy, a 1000x increase was observed in early pregnancy with a 10 000x increase seen by the third trimester. Following birth, kisspeptin-54 levels returned to normal, showing the placenta as the source of these increased kisspeptin levels.^[8]

Role in kidney function

Kisspeptin and its receptor was found in various sites in the kidney, including in the collecting duct, vascular smooth muscle, and in the renal tubule cells.^[13] Much of the impact on the kidney deals with the increased production of aldosterone in the adrenals glands stimulated by kisspeptin.^[14] Kisspeptin directly increases release of aldosterone by several means, the first being through these receptors leading to a direct route to aldosterone release.^[14] Secondly, the H295R adrenal cells stimulated by kisspeptin can synthesize aldosterone by breaking down pregnenolone more efficiently.^[14] Lastly, the kisspeptin-angiotensin II pathway of producing aldosterone is increased.^[14] Aldosterone that comes from the neighboring adrenal glands causes reabsorption of filtrate in order to retain water, leading to an increased blood pressure.^[15]

Kisspeptin neurons

Kisspeptin expressing neurons are located in:

Anteroventral periventricular nucleus (AVPV)
Periventricular nucleus (PeN)
Anterodorsal preoptic nucleus (ADP)
The arcuate nucleus (Arc)

Kisspeptin-expressing neurons reside in the anteroventral periventricular nucleus and the arcuate nucleus, among others, and send projections into the MPOA, where there is an abundance of GnRH cell bodies. This anatomical evidence suggests that Kisspeptin fibers appear in close anatomical relationship to GnRH (parvicellular) neurons. In fact, Kisspeptin appears to act directly on GnRH neurons (via GPR54) to stimulate the secretion of GnRH.

However, for kisspeptin to be involved in the regulation of GnRH release, it must also be sensitive to circulating sex steroid levels, as it is established that steroids produced by the gonads exert regulatory effects on FSH and LH levels through GnRH mediation. Thus, there are at least two possible scenarios: that either kisspeptin neurons express sex steroid receptors themselves, or they receive input about circulating sex steroid levels from a different mechanism .

Coexpression imaging of KISS1 mRNA (using vector red) and steroid receptors determined that neurons that express KISS1 mRNA are targets for the action of sex steroids in both male and female mice.

References

↑ Messager S, Chatzidaki EE, Ma D, Hendrick AG, Zahn D, Dixon J, Thresher RR, Malinge I, Lomet D, Carlton MB, Colledge WH, Caraty A, Aparicio SA (February 2005). "Kisspeptin directly stimulates gonadotropin-releasing hormone release via G protein-coupled receptor 54". Proceedings of the National Academy of Sciences of the United States of America. 102 (5): 1761–6. doi:10.1073/pnas.0409330102. PMC 545088. PMID 15665093.
↑ Lee JH, Miele ME, Hicks DJ, Phillips KK, Trent JM, Weissman BE, Welch DR (December 1996). "KiSS-1, a novel human malignant melanoma metastasis-suppressor gene". Journal of the National Cancer Institute. 88 (23): 1731–7. doi:10.1093/jnci/88.23.1731. PMID 8944003.
↑ Skorupskaite K, George JT, Anderson RA (2014). "The kisspeptin-GnRH pathway in human reproductive health and disease". Human Reproduction Update. 20 (4): 485–500. doi:10.1093/humupd/dmu009. PMC 4063702. PMID 24615662.
↑ ^4.00 ^4.01 ^4.02 ^4.03 ^4.04 ^4.05 ^4.06 ^4.07 ^4.08 ^4.09 ^4.10 ^4.11 Pasquier J, Kamech N, Lafont AG, Vaudry H, Rousseau K, Dufour S (June 2014). "Molecular evolution of GPCRs: Kisspeptin/kisspeptin receptors". Journal of Molecular Endocrinology. 52 (3): T101–17. doi:10.1530/JME-13-0224. PMID 24577719.
↑ ^5.0 ^5.1 ^5.2 ^5.3 ^5.4 ^5.5 ^5.6 ^5.7 Rønnekleiv OK, Kelly MJ. "Kisspeptin excitation of GnRH neurons". Advances in Experimental Medicine and Biology. 784: 113–131. doi:10.1007/978-1-4614-6199-9_6. PMC 4019505. PMID 23550004.
↑ Arai AC (January 2009). "The role of kisspeptin and GPR54 in the hippocampus". Peptides. 30 (1): 16–25. doi:10.1016/j.peptides.2008.07.023. PMID 18765263.
↑ Takahashi K, Shoji I, Shibasaki A, Kato I, Hiraishi K, Yamamoto H, Kaneko K, Murakami O, Morimoto R, Satoh F, Ito S, Totsune K (May 2010). "Presence of kisspeptin-like immunoreactivity in human adrenal glands and adrenal tumors". Journal of Molecular Neuroscience. 41 (1): 138–144. doi:10.1007/s12031-009-9306-4. PMID 19898965.
↑ ^8.0 ^8.1 ^8.2 Mead EJ, Maguire JJ, Kuc RE, Davenport AP (August 2007). "Kisspeptins: a multifunctional peptide system with a role in reproduction, cancer and the cardiovascular system". British Journal of Pharmacology. 151 (8): 1143–1153. doi:10.1038/sj.bjp.0707295. PMC 2189831. PMID 17519946.
↑ ^9.0 ^9.1 ^9.2 Smith JT, Clarke IJ (March 2007). "Kisspeptin expression in the brain: catalyst for the initiation of puberty". Reviews in Endocrine & Metabolic Disorders. 8 (1): 1–9. doi:10.1007/s11154-007-9026-4. PMID 17334929.
↑ "Entrez Gene: KISS1 KiSS-1 metastasis-suppressor".
↑ De Bond JA, Smith JT (March 2014). "Kisspeptin and energy balance in reproduction". Reproduction. 147 (3): R53–63. doi:10.1530/REP-13-0509. PMID 24327738.
↑ ^12.0 ^12.1 ^12.2 ^12.3 ^12.4 Rhie YJ (June 2013). "Kisspeptin/G protein-coupled receptor-54 system as an essential gatekeeper of pubertal development". Annals of Pediatric Endocrinology & Metabolism. 18 (2): 55–59. doi:10.6065/apem.2013.18.2.55. PMC 4027097. PMID 24904852.
↑ Bhattacharya M, Babwah AV (April 2015). "Kisspeptin: beyond the brain". Endocrinology. 156 (4): 1218–1227. doi:10.1210/en.2014-1915. PMID 25590245.
↑ ^14.0 ^14.1 ^14.2 ^14.3 Oakley AE, Clifton DK, Steiner RA (October 2009). "Kisspeptin signaling in the brain". Endocrine Reviews. 30 (6): 713–734. doi:10.1210/er.2009-0005. PMC 2761114. PMID 19770291.
↑ Coffman TM (June 2014). "The inextricable role of the kidney in hypertension". The Journal of Clinical Investigation. 124 (6): 2341–2347. doi:10.1172/JCI72274. PMC 4092877. PMID 24892708.

External links

KISS1+protein,+human at the US National Library of Medicine Medical Subject Headings (MeSH)

[pmid15665093-1] Messager S, Chatzidaki EE, Ma D, Hendrick AG, Zahn D, Dixon J, Thresher RR, Malinge I, Lomet D, Carlton MB, Colledge WH, Caraty A, Aparicio SA (February 2005). "Kisspeptin directly stimulates gonadotropin-releasing hormone release via G protein-coupled receptor 54". Proceedings of the National Academy of Sciences of the United States of America. 102 (5): 1761–6. doi:10.1073/pnas.0409330102. PMC 545088. PMID 15665093.

[Lee_1996-2] Lee JH, Miele ME, Hicks DJ, Phillips KK, Trent JM, Weissman BE, Welch DR (December 1996). "KiSS-1, a novel human malignant melanoma metastasis-suppressor gene". Journal of the National Cancer Institute. 88 (23): 1731–7. doi:10.1093/jnci/88.23.1731. PMID 8944003.

[SkorupskaiteGeorge2014-3] Skorupskaite K, George JT, Anderson RA (2014). "The kisspeptin-GnRH pathway in human reproductive health and disease". Human Reproduction Update. 20 (4): 485–500. doi:10.1093/humupd/dmu009. PMC 4063702. PMID 24615662.

[Molecular_Evolution_of_GPCRS:_Kisspeptin/Kisspeptin_receptors-4] 4.00 ^4.01 ^4.02 ^4.03 ^4.04 ^4.05 ^4.06 ^4.07 ^4.08 ^4.09 ^4.10 ^4.11 Pasquier J, Kamech N, Lafont AG, Vaudry H, Rousseau K, Dufour S (June 2014). "Molecular evolution of GPCRs: Kisspeptin/kisspeptin receptors". Journal of Molecular Endocrinology. 52 (3): T101–17. doi:10.1530/JME-13-0224. PMID 24577719.

[Kisspeptin_excitation_of_GnRH_neurons-5] 5.0 ^5.1 ^5.2 ^5.3 ^5.4 ^5.5 ^5.6 ^5.7 Rønnekleiv OK, Kelly MJ. "Kisspeptin excitation of GnRH neurons". Advances in Experimental Medicine and Biology. 784: 113–131. doi:10.1007/978-1-4614-6199-9_6. PMC 4019505. PMID 23550004.

[The_role_of_kisspeptin_and_GPR54_in_the_hippocampus-6] Arai AC (January 2009). "The role of kisspeptin and GPR54 in the hippocampus". Peptides. 30 (1): 16–25. doi:10.1016/j.peptides.2008.07.023. PMID 18765263.

[Presence_of_Kisspeptin-like_Immunoreactivity_in_Human_Adrenal_Glands_and_Adrenal_Tumors-7] Takahashi K, Shoji I, Shibasaki A, Kato I, Hiraishi K, Yamamoto H, Kaneko K, Murakami O, Morimoto R, Satoh F, Ito S, Totsune K (May 2010). "Presence of kisspeptin-like immunoreactivity in human adrenal glands and adrenal tumors". Journal of Molecular Neuroscience. 41 (1): 138–144. doi:10.1007/s12031-009-9306-4. PMID 19898965.

[Kisspeptins:_a_multifunctional_peptide_system_with_a_role_in_reproduction,_cancer_and_the_cardiovascular_system-8] 8.0 ^8.1 ^8.2 Mead EJ, Maguire JJ, Kuc RE, Davenport AP (August 2007). "Kisspeptins: a multifunctional peptide system with a role in reproduction, cancer and the cardiovascular system". British Journal of Pharmacology. 151 (8): 1143–1153. doi:10.1038/sj.bjp.0707295. PMC 2189831. PMID 17519946.

[Kisspeptin_expression_in_the_brain:_Catalyst_for_the_initiation_of_puberty-9] 9.0 ^9.1 ^9.2 Smith JT, Clarke IJ (March 2007). "Kisspeptin expression in the brain: catalyst for the initiation of puberty". Reviews in Endocrine & Metabolic Disorders. 8 (1): 1–9. doi:10.1007/s11154-007-9026-4. PMID 17334929.

[entrez-10] "Entrez Gene: KISS1 KiSS-1 metastasis-suppressor".

[Kisspeptin_and_energy_balance_in_reproduction-11] De Bond JA, Smith JT (March 2014). "Kisspeptin and energy balance in reproduction". Reproduction. 147 (3): R53–63. doi:10.1530/REP-13-0509. PMID 24327738.

[Kisspeptin/G_protein-coupled_receptor-54_system_as_an_essential_gatekeeper_of_pubertal_development-12] 12.0 ^12.1 ^12.2 ^12.3 ^12.4 Rhie YJ (June 2013). "Kisspeptin/G protein-coupled receptor-54 system as an essential gatekeeper of pubertal development". Annals of Pediatric Endocrinology & Metabolism. 18 (2): 55–59. doi:10.6065/apem.2013.18.2.55. PMC 4027097. PMID 24904852.

[Kisspeptin:_Beyond_the_Brain-13] Bhattacharya M, Babwah AV (April 2015). "Kisspeptin: beyond the brain". Endocrinology. 156 (4): 1218–1227. doi:10.1210/en.2014-1915. PMID 25590245.

[Kisspeptin_Signaling_in_the_Brain-14] 14.0 ^14.1 ^14.2 ^14.3 Oakley AE, Clifton DK, Steiner RA (October 2009). "Kisspeptin signaling in the brain". Endocrine Reviews. 30 (6): 713–734. doi:10.1210/er.2009-0005. PMC 2761114. PMID 19770291.

[The_inextricable_role_of_the_kidney_in_hypertension-15] Coffman TM (June 2014). "The inextricable role of the kidney in hypertension". The Journal of Clinical Investigation. 124 (6): 2341–2347. doi:10.1172/JCI72274. PMC 4092877. PMID 24892708.

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-<!-- The PBB_Controls template provides controls for Protein Box Bot, please see Template:PBB_Controls for details. -->
+{{Use dmy dates|date=April 2016}}
-{{PBB_Controls
+{{Infobox_gene}}
-| update_page = yes
+'''Kisspeptin''' (formerly known as '''metastin''') is a [[protein]] that is encoded by the ''KISS1'' [[gene]] in humans. Kisspeptin is a [[G-protein coupled receptor]] [[Ligand (biochemistry)|ligand]] for [[KiSS1-derived peptide receptor|GPR54]].<ref name="pmid15665093">{{cite journal | vauthors = Messager S, Chatzidaki EE, Ma D, Hendrick AG, Zahn D, Dixon J, Thresher RR, Malinge I, Lomet D, Carlton MB, Colledge WH, Caraty A, Aparicio SA | title = Kisspeptin directly stimulates gonadotropin-releasing hormone release via G protein-coupled receptor 54 | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 102 | issue = 5 | pages = 1761–6  | date = February 2005 | pmid = 15665093 | pmc = 545088 | doi = 10.1073/pnas.0409330102 }}</ref> ''Kiss1'' was originally identified as a human [[metastasis suppressor]] gene that has the ability to suppress [[melanoma]] and breast cancer [[metastasis]].<ref name="Lee_1996">{{cite journal | vauthors = Lee JH, Miele ME, Hicks DJ, Phillips KK, Trent JM, Weissman BE, Welch DR | title = KiSS-1, a novel human malignant melanoma metastasis-suppressor gene | journal = Journal of the National Cancer Institute | volume = 88 | issue = 23 | pages = 1731–7 | date = December 1996 | pmid = 8944003 | doi = 10.1093/jnci/88.23.1731 }}</ref> Kisspeptin-GPR54 signaling has an important role in initiating secretion of [[gonadotropin-releasing hormone]] (GnRH) at puberty, the extent of which is an area of ongoing research.<ref name="SkorupskaiteGeorge2014">{{cite journal | vauthors = Skorupskaite K, George JT, Anderson RA | title = The kisspeptin-GnRH pathway in human reproductive health and disease | journal = Human Reproduction Update | volume = 20 | issue = 4 | pages = 485–500 | year = 2014 | pmid = 24615662 | doi = 10.1093/humupd/dmu009 | pmc=4063702}}</ref> Gonadotropin-releasing hormone is released from the hypothalamus to act on the [[anterior pituitary]] triggering the release of [[luteinizing hormone]] (LH), and [[follicle stimulating hormone]] (FSH). These gonadotropic hormones lead to sexual maturation and [[gametogenesis]]. Disrupting GPR54 signaling can cause [[hypogonadotrophic hypogonadism]] in rodents and humans. The Kiss1 gene is located on chromosome 1.  It is transcribed in the brain, adrenal gland, and pancreas.
-| require_manual_inspection = no
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-}}
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-{{GNF_Protein_box
- | image =
- | image_source =
- | PDB =
- | Name = KiSS-1 metastasis-suppressor
- | HGNCid = 6341
- | Symbol = KISS1
- | AltSymbols =; KiSS-1; MGC39258
- | OMIM = 603286
-  | ECnumber =
- | Homologene = 1701
- | MGIid = 2663985
- | GeneAtlas_image1 = PBB_GE_KISS1_205563_at_tn.png
- | Function = {{GNF_GO|id=GO:0005515 |text = protein binding}}
- | Component =
- | Process = {{GNF_GO|id=GO:0007010 |text = cytoskeleton organization and biogenesis}}
- | Orthologs = {{GNF_Ortholog_box
-    | Hs_EntrezGene = 3814
-    | Hs_Ensembl = ENSG00000170498
-    | Hs_RefseqProtein = NP_002247
-    | Hs_RefseqmRNA = NM_002256
-    | Hs_GenLoc_db =
-    | Hs_GenLoc_chr = 1
-    | Hs_GenLoc_start = 202426092
-    | Hs_GenLoc_end = 202432251
-    | Hs_Uniprot = Q15726
-    | Mm_EntrezGene = 280287
-    | Mm_Ensembl =
-    | Mm_RefseqmRNA = NM_178260
-    | Mm_RefseqProtein = NP_839991
-    | Mm_GenLoc_db =
-    | Mm_GenLoc_chr =
-    | Mm_GenLoc_start =
-    | Mm_GenLoc_end =
-    | Mm_Uniprot =
-  }}
-}}
-{{SI}}
+== History ==
+<!-- Commented out: [[File:HersheyCo.PNG|thumb|HersheyCo|alt=HersheyCo.PNG]] -->
+In 1996, Dr. Danny Welch's lab in Hershey, Pennsylvania isolated a [[cDNA]] from a cancer cell that was not able to undergo [[metastasis]] after the human [[chromosome 6]] was added to the cell.  This [[gene]] was named KISS1 because of the location of where it was discovered (Hershey, Pennsylvania, home of [[Hershey's Kisses]]).  Introduction of this chromosome into the once active cancer cell inhibited it from spreading and the cDNA responsible was taken from that cell.  The fact that KISS1 was responsible for this was proved when it was transfected into [[melanoma]] cells and yet again, metastasis was suppressed.<ref name="Molecular Evolution of GPCRS: Kisspeptin/Kisspeptin receptors">{{cite journal | vauthors = Pasquier J, Kamech N, Lafont AG, Vaudry H, Rousseau K, Dufour S | title = Molecular evolution of GPCRs: Kisspeptin/kisspeptin receptors | journal = Journal of Molecular Endocrinology | volume = 52 | issue = 3 | date = June 2014 | pmid = 24577719 | doi = 10.1530/JME-13-0224 | pages=T101-17}}</ref> Later, a breakthrough would occur not involving Kisspeptin, but with its receptor.
-'''Kisspeptin''' the product of the gene {{gene|Kiss1}} is a [[G-protein coupled receptor]] [[Ligand (biochemistry)|ligand]] for [[KiSS1-derived peptide receptor|GPR54]].<ref name="pmid15665093">{{cite journal | author = Messager S, Chatzidaki EE, Ma D, Hendrick AG, Zahn D, Dixon J, Thresher RR, Malinge I, Lomet D, Carlton MB, Colledge WH, Caraty A, Aparicio SA | title = Kisspeptin directly stimulates gonadotropin-releasing hormone release via G protein-coupled receptor 54 | journal = Proc. Natl. Acad. Sci. U.S.A. | volume = 102 | issue = 5 | pages = 1761–6 | year = 2005 | pmid = 15665093 | doi = 10.1073/pnas.0409330102 | issn = }}</ref> ''Kiss1'' was originally identified as a human [[metastasis suppressor]] gene that has the ability to suppress [[melanoma]] and [[breast cancer]] [[metastasis]]. It is recently become clear that kisspeptin-GPR54 signaling has an important role in initiating GnRH secretion at puberty, the extent of which is an area of ongoing research.<ref name="pmid16595713">{{cite journal | author = Smith JT, Clifton DK, Steiner RA | title = Regulation of the neuroendocrine reproductive axis by kisspeptin-GPR54 signaling | journal = Reproduction | volume = 131 | issue = 4 | pages = 623–30 | year = 2006 | pmid = 16595713 | doi = 10.1530/rep.1.00368 | issn = }}</ref><ref name="pmid16373418">{{cite journal | author = Dungan HM, Clifton DK, Steiner RA | title = Minireview: kisspeptin neurons as central processors in the regulation of gonadotropin-releasing hormone secretion | journal = Endocrinology | volume = 147 | issue = 3 | pages = 1154–8 | year = 2006 | pmid = 16373418 | doi = 10.1210/en.2005-1282 | issn = }}</ref>
+Three years later in 1999, a [[G protein coupled receptor]] was identified in rat, cloned, and termed GPR54.<ref name="Molecular Evolution of GPCRS: Kisspeptin/Kisspeptin receptors"/>  Additionally, two years later, this receptor’s [[ortholog]] in humans would be isolated.<ref name="Molecular Evolution of GPCRS: Kisspeptin/Kisspeptin receptors"/>  Using the identified receptors, [[endogenous]] [[ligands]] were isolated from cells (HEK293, B16-BL6, and CHO-K1 cells) that had these receptors inserted into them.<ref name="Molecular Evolution of GPCRS: Kisspeptin/Kisspeptin receptors"/>  The next step in the history of Kisspeptin involved revealing more of its pathways and the mechanism involved.
+Kisspeptin was found to play a role in [[hypogonadotropic hypogonadism]] in 2003, which was supported by several independent lab groups.<ref name="Molecular Evolution of GPCRS: Kisspeptin/Kisspeptin receptors"/>  A [[mutation]] in GPR54 was considered responsible for this abnormality because those who held this mutation, or were missing GPR54 altogether, had problems in gonadal development during [[puberty]].<ref name="Molecular Evolution of GPCRS: Kisspeptin/Kisspeptin receptors"/>  Several other [[phenotypes]] related to this mutation included a smaller [[sex steroid]] and [[gonadotropin]] [[concentration]] in the circulating blood and even [[sterility (physiology)|sterility]].<ref name="Molecular Evolution of GPCRS: Kisspeptin/Kisspeptin receptors"/>  These observations prompted the research on how kisspeptin is involved during the beginning of puberty.  This research led to the discovery that kisspeptin stimulates the neurons that were involved in the release of [[gonadotropin-releasing hormone]] (GnRH) and possibly may have some impact on the release of [[luteinizing hormone]] (LH) and [[follicle-stimulating hormone]] (FSH).<ref name="Molecular Evolution of GPCRS: Kisspeptin/Kisspeptin receptors"/>
-This gene is a metastasis suppressor gene that suppresses metastases of melanomas and breast carcinomas without affecting tumorigenicity. The encoded protein may function to inhibit chemotaxis and invasion, attenuating metastasis in malignant melanomas. Studies suggest a putative role in the regulation of events downstream of cell-matrix adhesion, perhaps involving cytoskeletal reorganization. A polymorphism in the terminal exon of this mRNA results in two protein isoforms. An adenosine present at the polymorphic site represents the third position in a stop codon. When the adenosine is absent, a downstream stop codon is utilized and the encoded protein extends for an additional seven amino acid residues.<ref name="entrez">{{cite web | title = Entrez Gene: KISS1 KiSS-1 metastasis-suppressor| url = http://www.ncbi.nlm.nih.gov/sites/entrez?Db=gene&Cmd=ShowDetailView&TermToSearch=3814| accessdate = }}</ref>
+Today, much effort is being made to characterize the regulation of kisspeptin and its [[gene expression]], as well as to more specifically determine the mechanism behind kisspeptin's action on GnRH and LH release.<ref name="Kisspeptin excitation of GnRH neurons">{{cite journal | vauthors = Rønnekleiv OK, Kelly MJ | title = Kisspeptin excitation of GnRH neurons | journal = Advances in Experimental Medicine and Biology | volume = 784 | pmid = 23550004 | doi = 10.1007/978-1-4614-6199-9_6 | pmc=4019505 | pages=113–131}}</ref>
-==History==
+== Sources ==
-The [[Receptor (biochemistry)|receptor]] for kisspeptin, GPR54, was first identified as an orphan [[GPCR]] in rat in 1999.<ref>{{cite journal |author=Lee D, Nguyen T, O'Neill G, Cheng R, Liu Y, Howard A, Coulombe N, Tan C, Tang-Nguyen A, George S, O'Dowd B |title=Discovery of a receptor related to the galanin receptors |journal=FEBS Lett |volume=446 |issue=1 |pages=103-7 |year=1999 |id=PMID 10100623}}</ref> Following in 2001, a natural [[ligand]] for GPR54 was discovered, which was the product of the Kiss1 gene, originally identified as a human [[metastasis]] suppressor gene.<ref>{{cite journal |author=Kotani M, Detheux M, Vandenbogaerde A, Communi D, Vanderwinden J, Le Poul E, Brézillon S, Tyldesley R, Suarez-Huerta N, Vandeput F, Blanpain C, Schiffmann S, Vassart G, Parmentier M |title=The metastasis suppressor gene KiSS-1 encodes kisspeptins, the natural ligands of the orphan G protein-coupled receptor GPR54 |journal=J Biol Chem |volume=276 |issue=37 |pages=34631-6 |year=2001 |id=PMID 11457843}}</ref> Subsequent mutant studies led to the discovery that [[mutation|LOF mutations]] in GPR54 causes failure to progress through [[puberty]] in man, due to [[hypogonadism|hypogonadotropic hypogonadism]]. Thus, it was concluded that Kisspeptin-GPR54 signaling is essential to initiate gonadotropin (LH/FSH) secretion at puberty.
-Interestingly, the naming of the Kiss-1 gene and its product, kisspeptin, was made by the team of scientists who discovered the gene in [[Hershey, Pennsylvania]], famous for its chocolate "kisses".
+=== Hippocampal dentate gyrus ===
+[[File:Hypothalamus small.gif|thumb|Human hypothalamus (shown in red)]]
+Kisspeptin is most notably expressed in the [[hypothalamus]], but is also found in other areas of the brain including the hippocampal [[dentate gyrus]]. The hippocampus is known to integrate information on a person's spatial environment and [[memory]]. KISS1 is known to be expressed in the [[hippocampus]]. However, the levels of KISS1 [[mRNA]] expressed are decidedly lower than in the [[hypothalamus]] and [[amygdala]]. Studies have shown that the levels of KISS1 mRNA expressed in the hippocampus are proportional to less than half of the levels found in the hypothalamus. Despite this, it is suggested that expression of KISS1 is influenced by the [[gonad]] hormones similar to the hypothalamus.
+There is a high degree of expression of GPR54 in the hippocampus. The density of GPR54 is not discernable in [[pyramidal cells]], but has high levels of expression in the [[granule cell]] layer. It is known to be found in specific nuclei and neurons.<ref name="The role of kisspeptin and GPR54 in the hippocampus">{{cite journal | vauthors = Arai AC | title = The role of kisspeptin and GPR54 in the hippocampus | journal = Peptides | volume = 30 | issue = 1 | pages = 16–25 | date = January 2009 | pmid = 18765263 | doi = 10.1016/j.peptides.2008.07.023 }}</ref>
-==Kisspeptin Neurons==
+=== Adrenal gland ===
-Kisspeptin expressing neurons are located in:
+The neuropeptide kisspeptin plays an important role in [[reproduction]], but also stimulates [[aldosterone]] secretion from the [[adrenal cortex]]. Kisspeptin is distributed from the adrenal cortex and it is transcribed in the [[neocortex]]. The exact nature of the expression of kisspeptins in human adrenal glands unfortunately has not been fully clarified yet and remains a large topic of research among many scientists.<ref name="Presence of Kisspeptin-like Immunoreactivity in Human Adrenal Glands and Adrenal Tumors">{{cite journal | vauthors = Takahashi K, Shoji I, Shibasaki A, Kato I, Hiraishi K, Yamamoto H, Kaneko K, Murakami O, Morimoto R, Satoh F, Ito S, Totsune K | title = Presence of kisspeptin-like immunoreactivity in human adrenal glands and adrenal tumors | journal = Journal of Molecular Neuroscience | volume = 41 | issue = 1 | pages = 138–144 | date = May 2010 | pmid = 19898965 | doi = 10.1007/s12031-009-9306-4 }}</ref>
-* Anteroventral [[periventricular nucleus]] (AVPV)
-* [[Periventricular nucleus]]  (PeN)
+== Genomics ==
-* Anterodorsal [[preoptic nucleus]] (ADP)
-* The [[arcuate nucleus]] (Arc)
+Kisspeptin is a product of the KISS1 gene which is cleaved from an initial 145 [[amino acid]] peptide to a 54 amino acid long protein.<ref name="Kisspeptins: a multifunctional peptide system with a role in reproduction, cancer and the cardiovascular system">{{cite journal | vauthors = Mead EJ, Maguire JJ, Kuc RE, Davenport AP | title = Kisspeptins: a multifunctional peptide system with a role in reproduction, cancer and the cardiovascular system | journal = British Journal of Pharmacology | volume = 151 | issue = 8 | pages = 1143–1153 | date = August 2007 | pmid = 17519946 | doi = 10.1038/sj.bjp.0707295 | pmc=2189831}}</ref> This gene is located on the long arm of [[chromosome 1]] (1q32) and has four exons of which the 5' and 3' exons only partly undergo [[translation (biology)|translation]]. The KISS1 gene was first isolated as a tumor spreading gene by investigators and named metastin.  [[Metastin]] is derived from the protein kisspeptin and is a natural [[ligand]] of the receptor known as GPR54 Kisspeptin expression in the brain: Catalyst for the initiation of puberty.<ref name="Kisspeptin expression in the brain: Catalyst for the initiation of puberty">{{cite journal | vauthors = Smith JT, Clarke IJ | title = Kisspeptin expression in the brain: catalyst for the initiation of puberty | journal = Reviews in Endocrine & Metabolic Disorders | volume = 8 | issue = 1 | date = March 2007 | pmid = 17334929 | doi = 10.1007/s11154-007-9026-4 | pages=1–9}}</ref> Different types made up of 14 and 13 amino acids have been isolated and they each share a common [[C-terminal]] sequence. These N-terminally truncated peptides are known as the kisspeptins and belong to a larger family of peptides known as RFamides which all share a common [[arginine]]-[[phenylalanine]]-NH2 motif at their C-terminus. Among these conserved amino acids are [[arginine]] and [[phenylalanine]] residues, which are paired in this family of peptides.  Also within this conserved family is a C-terminus that has an [[amide]] added to it. This family which kisspeptin includes [[prolactin]] releasing peptide and gonadotropin releasing inhibiting hormone.<ref name="Kisspeptin expression in the brain: Catalyst for the initiation of puberty"/>
+A [[polymorphism (biology)|polymorphism]] in the terminal [[exon]] of this [[messenger RNA|mRNA]] results in two [[protein isoform]]s. An adenosine present at the polymorphic site represents the third position in a stop codon. When the [[adenosine]] is absent, a downstream [[stop codon]] is utilized and the encoded protein extends for an additional seven amino acid residues.<ref name="entrez">{{cite web | title = Entrez Gene: KISS1 KiSS-1 metastasis-suppressor| url = https://www.ncbi.nlm.nih.gov/sites/entrez?Db=gene&Cmd=ShowDetailView&TermToSearch=3814| accessdate = }}</ref>
+== Structure ==
+=== Kisspeptin ===
+The [[gene]] for kisspeptin codes for a [[peptide]] that can be cleaved into several pieces.<ref name="Kisspeptin excitation of GnRH neurons"/> In humans, one of these pieces is made up of 54 amino acids, while in mice it is made up of 52 [[amino acids]].<ref name="Kisspeptin and energy balance in reproduction">{{cite journal | vauthors = De Bond JA, Smith JT | title = Kisspeptin and energy balance in reproduction | journal = Reproduction | volume = 147 | issue = 3 | date = March 2014 | pmid = 24327738 | doi = 10.1530/REP-13-0509 | pages=R53-63}}</ref> This fragment is then proteolytically processed into several smaller fragments that have been isolated in humans composed of 13 and 14 amino acids (kisspeptin-13 and kisspeptin-14 respectively).  Each of these fragments has a similar conserved region at the [[C-terminal]] sequence consisting of ten amino acids.<ref name= "Molecular Evolution of GPCRS: Kisspeptin/Kisspeptin receptors"/>  Specifically, positions 2, 4, 6, 7, 8, and 9 in this region are completely conserved where any variation seen is due to random mutations.  The sequence on the carboxy terminal side of the conserved region is a well-known site for cleavage in [[neuropeptides]].<ref name= "Molecular Evolution of GPCRS: Kisspeptin/Kisspeptin receptors"/>
+=== GPR54 ===
+The structure for GPR54 is very similar throughout many different [[vertebrates]].<ref name="Molecular Evolution of GPCRS: Kisspeptin/Kisspeptin receptors"/>  It is composed of 398 amino acids that form seven [[transmembrane]] domains, like most [[G-protein coupled receptors]].  Sequences found in transmembrane spanning regions one, four, and seven are all very highly conserved throughout species.  Variation appears in the around the amino and C-terminal domains, which accounts for the different types of Kisspeptin [[receptor (biochemistry)|receptor]]s seen in various [[species]].<ref name="Molecular Evolution of GPCRS: Kisspeptin/Kisspeptin receptors"/>
+==Pathway==
-Kisspeptin neurons reside in nuclei such as Arc and AVPV and send projections into the [[MPOA]], where there is an abundance of GnRH cell bodies. This anatomical evidence suggests that Kisspeptin fibers appear in close anatomical relationship to GnRH (parvicellular) neurons. In fact, Kisspeptin appears to act directly on GnRH neurons (via GPR54) to stimulate the secretion of GnRH.
+===GnRH release===
+[[File:GNRH1 structure.png|thumb|GNRH1 structure|alt=GNRH1 structure.png]]
+Kisspeptin-54 interacts with [[G protein-coupled receptors]], specifically GPR54 (Kiss1R). Other versions of kisspeptin are also able to interact with Kiss1R.<ref name="Kisspeptin excitation of GnRH neurons"/> Research in both rats and humans has provided evidence that the binding of kisspeptin stimulates PIP2 [[hydrolysis]], Ca<sup>2+</sup> mobilization, [[arachidonic acid]] release, extracellular signal-regulated [[protein kinase]] 1 (ERK1), ERK2, and p38 MAP kinase phosphorylation.<ref name="Kisspeptin excitation of GnRH neurons"/> Although GnRH is located in many areas such as the [[pituitary gland]] and the GnRH neurons, research proves that [[GnRH]] is highly dependent upon GnRH neuron activation and less dependent on the [[pituitary]] gonadotropes.<ref name="Kisspeptin excitation of GnRH neurons"/> Many studies show that kisspeptin has the ability to not only cause [[depolarization]], but also excite many GnRH neurons, leading to high expression of kisspeptin in these [[genes]].<ref name="Kisspeptin excitation of GnRH neurons"/> But, it is hypothesized that there are two different types of GFP-GnRH neurons due to expression in some [[neurons]] but not others, only one of which responds to kisspeptin.<ref name="Kisspeptin excitation of GnRH neurons"/> The neurons response to kisspeptin is also hypothesized to be related to age and [[puberty]].<ref name="Kisspeptin excitation of GnRH neurons"/> The binding of kisspeptin to the GnRH receptor can have effects on puberty, [[tumor]] suppression and [[reproduction]].
-However, for kisspeptin to be involved in the regulation of GnRH release, it must also be sensitive to steroid levels within the circulation, as it has already been established that steroids produced by the gonads exert regulatory effects on FSH and LH levels through GnRH mediation. Therefore, there are (at least) two possible scenarios: That either kisspeptin neurons express steroid receptors (such as ERα, ERβ, and [[androgen receptor|AR]]) themselves, or they receive input from another mechanism about circulating steroid levels.
+== Biological function ==
-Coexpression imaging of Kiss-1 mRNA (using [[vector red]]) and steroid receptors determined that KiSS-1 neurons are direct target for the action of sex steroids in both the male and female mouse.
+Kisspeptin can stimulate secretion of [[aldosterone]] and the release of [[insulin]].
-==Role in Puberty==
-The following evidence has been sited to support a role for kisspeptin in puberty:
-* Animals with LOF mutations and targeted deletions of GPR54 fail to progress through puberty as a result of hypogonadotropic * hypogonadism (HH).
-* Activation of GnRH neurons is the key event that initiates the onset of puberty.
-* Peripheral administration of kisspeptin to prepubertal, 25-day-old female rats stimulates LH secretion and induces ovulation in the rat.
-* If kisspeptins trigger puberty onset, one would expect to see an increase in KiSS-1 mRNA and/or GPR54 mRNA expression during this time. RT-PCR essays and semiquantitative results support this hypothesis.
-* The electrophysiologic response of GnRH neurons to kisspeptins appears to change dramatically over the course of puberty.
-===Mechanism of Action===
 Kisspeptin appears to directly activate GnRH neurons. Evidence for this involves the persistence of a neural response to kisspeptin levels even in the presence of TTX, a neurotoxin that blocks nerve signals.
+* [[Gramicidin]]-perforated patch recordings: about 30% of GnRH neurons respond to kisspeptin administration in prepubertal males, whereas 60% of GnRH neurons in adult mice responded.
+* Because only adult mice respond to low doses of kisspeptin, it appears that GnRH neurons become developmentally activated by kisspeptin over the course of puberty.
+* Kisspeptin induces production of LH and FSH, which are required for female's menstruation. Athletes may not undergo menstruation due to low fat levels; fat produces the hormone [[leptin]], which induces production of kisspeptin.
+=== Role in puberty ===
+The onset of [[puberty]] is marked by an increase in [[gonadotropin]] secretion, which leads to sexual maturity and the ability to reproduce. Puberty can also be affected by a range of environmental factors, and is known to be affected by a person's metabolic capacity.<ref name="Kisspeptin/G protein-coupled receptor-54 system as an essential gatekeeper of pubertal development">{{cite journal | vauthors = Rhie YJ | title = Kisspeptin/G protein-coupled receptor-54 system as an essential gatekeeper of pubertal development | journal = Annals of Pediatric Endocrinology & Metabolism | volume = 18 | issue = 2 | pages = 55–59 | date = June 2013 | pmid = 24904852 | doi = 10.6065/apem.2013.18.2.55 | pmc=4027097}}</ref> Gonadotropin secretion is brought about and regulated by [[gonadotropin releasing hormone]] (GnRH). GnRH leads to the release of [[luteinizing hormone]] (LH) and [[follicle stimulating hormone]] (FSH), which primarily target the [[gonads]] to trigger puberty and [[reproduction]]. The primary event that leads to the beginning of puberty is the activation of GnRH neurons. This event is thought to involve kisspeptin/GPR54 signaling, which leads to the eventual activation of GnRH [[neurons]].<ref name="Kisspeptin expression in the brain: Catalyst for the initiation of puberty"/>
+Several studies have confirmed that addition of kisspeptin to biological systems including rat, mouse, and sheep are able to bring about the release of LH and FSH.  In addition to this, the release of these gonadotropins has proven to be dose dependent. A greater addition of kisspeptin peptide resulted in greater release of LH and FSH. Kisspeptin was found to evoke one of the strongest effects on the gonadotropin system.<ref name="Kisspeptin/G protein-coupled receptor-54 system as an essential gatekeeper of pubertal development"/>
-* Gramicidin-perforated patch recordings: approx. 30% of GnRH neurons respond to kisspeptin administration in prepubertal males, whereas 60% of GnRH neurons in adult mice responded.
+[[File:Figure 28 03 01.jpg|thumb|Figure 28 03 01|alt=Figure 28 03 01.jpg]]
-* Because only adult mice respond to low doses of kisspeptin, it appears that GnRH neurons become developmentally activated by kisspeptin over the course of puberty.
+Kisspeptin's ability to stimulate the release of GnRH and [[gonadotropins]] is the result of its effect on GnRH release at the [[hypothalamus]]. In rat hypothalamus, it was found that over three-fourths of GnRH neurons coexpress the receptor for kisspeptin, GPR54, in their RNA. Kisspeptin was also able to bring about the release of GnRH both ex vivo and in vivo in rat and sheep. It can be concluded that by activating GnRH neurons in the hypothalamus, kisspeptin causes GnRH release which leads to the release of FSH and LH.<ref name="Kisspeptin/G protein-coupled receptor-54 system as an essential gatekeeper of pubertal development"/> The major role kisspeptin/GPR54 plays in [[sexual development]] was initially found in sexually immature humans and mice who had [[mutations]] that blocked the expression of the GPR54 gene. In rats, the initiation of puberty accompanied a greater presence of KISS1 and GPR54 in mRNA. The same events were later observed in [[mammals]], where KISS1 and GPR54 mRNA increased more than twofold in the [[hypothalamus]]. This suggests that there is greater expression of KISS1 and potentially even GPR54 at the onset of puberty leading to an increase in kisspeptin/GPR54 signaling that results in the activation of the [[gonadotropin]] pathway.<ref name="Kisspeptin/G protein-coupled receptor-54 system as an essential gatekeeper of pubertal development"/> The addition of kisspeptin to female rats who had yet to mature led to the initiation of gonadotropin pathway. In humans, it was shown that females at the beginning stages of puberty had much higher kisspeptin levels than those females of the same age who had yet to begin puberty. It has been concluded that the activation of the GPR54/kisspeptin pathway is a catalyst that leads to puberty onset.<ref name="Kisspeptin/G protein-coupled receptor-54 system as an essential gatekeeper of pubertal development"/>
+=== Role in tumor suppression ===
+Kisspeptin plays a role in [[tumor]] suppression.  In a study where [[malignant]] tumor cells were injected into a [[Scientific modelling|model system]], the system was then tested for genes involved in the injected chromosome 6. KISS1 was discovered to be the only gene expressed in non-metastatic cells and absent in metastatic, metastatic meaning the ability for cancer to spread to unconnected areas. This suggested that there Kisspeptin is an essential regulation factor in whether or not a cell will be [[metastatic]] or not. Additional experimentation identified CRSP3 as the exact gene responsible for KISS1 regulation within chromosome 6. In clinical evidence studies, KISS1 and Kisspeptin were found in primary, metastatic tumors, and growing tumors showing decreased levels of KISS1 and Kisspeptin.<ref name="Kisspeptins: a multifunctional peptide system with a role in reproduction, cancer and the cardiovascular system"/> In conclusion, kisspeptin plays a large role in [[tumor suppression]]. When it is active in cells the tumor stays [[wikt:consolidated|consolidated]] and does not spread or grow.
+=== Role in reproduction ===
+Kisspeptin is highly expressed during pregnancy. In early-term placentas, GPR54 was expressed at a higher rate than placentas at-term. The expression of kisspeptin, however, remains unchanged in the placenta throughout pregnancy. The increased expression of GPR54 in early-term placentas is due to the increased presence of intrusive [[trophoblasts]] during the beginning of pregnancy. Term cells, by comparison are less invasive. When measuring kisspeptin-54 during pregnancy, a 1000x increase was observed in early pregnancy with a 10 000x increase seen by the third trimester. Following birth, kisspeptin-54 levels returned to normal, showing the [[placenta]] as the source of these increased kisspeptin levels.<ref name="Kisspeptins: a multifunctional peptide system with a role in reproduction, cancer and the cardiovascular system"/>
+=== Role in kidney function ===
+Kisspeptin and its receptor was found in various sites in the kidney, including in the [[collecting duct]], [[vascular smooth muscle]], and in the [[renal]] tubule cells.<ref name="Kisspeptin: Beyond the Brain">{{cite journal | vauthors = Bhattacharya M, Babwah AV | title = Kisspeptin: beyond the brain | journal = Endocrinology | volume = 156 | issue = 4 | pages = 1218–1227 | date = April 2015 | pmid = 25590245 | doi = 10.1210/en.2014-1915 }}</ref> Much of the impact on the kidney deals with the increased production of [[aldosterone]] in the adrenals glands stimulated by kisspeptin.<ref name="Kisspeptin Signaling in the Brain ">{{cite journal | vauthors = Oakley AE, Clifton DK, Steiner RA | title = Kisspeptin signaling in the brain | journal = Endocrine Reviews | volume = 30 | issue = 6 | pages = 713–734 | date = October 2009 | pmid = 19770291 | doi = 10.1210/er.2009-0005 | pmc=2761114}}</ref> Kisspeptin directly increases release of aldosterone by several means, the first being through these receptors leading to a direct route to [[aldosterone]] release.<ref name="Kisspeptin Signaling in the Brain "/> Secondly, the [[H295R]] adrenal cells stimulated by kisspeptin can synthesize aldosterone by breaking down [[pregnenolone]] more efficiently.<ref name="Kisspeptin Signaling in the Brain "/> Lastly, the kisspeptin-angiotensin II pathway of producing aldosterone is increased.<ref name="Kisspeptin Signaling in the Brain "/> Aldosterone that comes from the neighboring [[adrenal gland]]s causes reabsorption of filtrate in order to retain water, leading to an increased [[blood pressure]].<ref name="The inextricable role of the kidney in hypertension">{{cite journal | vauthors = Coffman TM | title = The inextricable role of the kidney in hypertension | journal = The Journal of Clinical Investigation | volume = 124 | issue = 6 | pages = 2341–2347 | date = June 2014 | pmid = 24892708 | doi = 10.1172/JCI72274 | pmc = 4092877 }}</ref>
+== Kisspeptin neurons ==
+[[Structural Biochemistry/ Kiss Gene Expression|Kisspeptin expressing neurons]] are located in:
+* Anteroventral [[periventricular nucleus]] (AVPV)
+* [[Periventricular nucleus]] (PeN)
+* Anterodorsal preoptic nucleus (ADP)
+* The [[arcuate nucleus]] (Arc)
-==References==
+Kisspeptin-expressing neurons reside in the anteroventral periventricular nucleus and the arcuate nucleus, among others, and send projections into the [[MPOA]], where there is an abundance of GnRH cell bodies. This anatomical evidence suggests that Kisspeptin fibers appear in close anatomical relationship to GnRH (parvicellular) neurons. In fact, Kisspeptin appears to act directly on GnRH neurons (via GPR54) to stimulate the secretion of GnRH.
-{{Reflist|2}}
-==Further reading==
+However, for kisspeptin to be involved in the regulation of GnRH release, it must also be sensitive to circulating sex steroid levels, as it is established that steroids produced by the gonads exert regulatory effects on FSH and LH levels through GnRH mediation. Thus, there are at least two possible scenarios: that either kisspeptin neurons express sex steroid receptors themselves, or they receive input about circulating sex steroid levels from a different mechanism .
-{{refbegin | 2}}
-{{PBB_Further_reading
-| citations =
-*{{cite journal  | author=Harms JF, Welch DR, Miele ME |title=KISS1 metastasis suppression and emergent pathways. |journal=Clin. Exp. Metastasis |volume=20 |issue= 1 |pages= 11-8 |year= 2003 |pmid= 12650602 |doi=  }}
-*{{cite journal  | author=Kaiser UB, Kuohung W |title=KiSS-1 and GPR54 as new players in gonadotropin regulation and puberty. |journal=Endocrine |volume=26 |issue= 3 |pages= 277-84 |year= 2006 |pmid= 16034182 |doi=  }}
-*{{cite journal  | author=Nash KT, Welch DR |title=The KISS1 metastasis suppressor: mechanistic insights and clinical utility. |journal=Front. Biosci. |volume=11 |issue=  |pages= 647-59 |year= 2006 |pmid= 16146758 |doi=  }}
-*{{cite journal  | author=Tena-Sempere M |title=GPR54 and kisspeptin in reproduction. |journal=Hum. Reprod. Update |volume=12 |issue= 5 |pages= 631-9 |year= 2006 |pmid= 16731583 |doi= 10.1093/humupd/dml023 }}
-*{{cite journal  | author=Dhillo WS, Murphy KG, Bloom SR |title=The neuroendocrine physiology of kisspeptin in the human. |journal=Reviews in endocrine & metabolic disorders |volume=8 |issue= 1 |pages= 41-6 |year= 2007 |pmid= 17323132 |doi= 10.1007/s11154-007-9029-1 }}
-*{{cite journal  | author=Smith JT, Clarke IJ |title=Kisspeptin expression in the brain: catalyst for the initiation of puberty. |journal=Reviews in endocrine & metabolic disorders |volume=8 |issue= 1 |pages= 1-9 |year= 2007 |pmid= 17334929 |doi= 10.1007/s11154-007-9026-4 }}
-*{{cite journal  | author=Lee JH, Miele ME, Hicks DJ, ''et al.'' |title=KiSS-1, a novel human malignant melanoma metastasis-suppressor gene. |journal=J. Natl. Cancer Inst. |volume=88 |issue= 23 |pages= 1731-7 |year= 1996 |pmid= 8944003 |doi=  }}
-*{{cite journal  | author=Lee JH, Welch DR |title=Identification of highly expressed genes in metastasis-suppressed chromosome 6/human malignant melanoma hybrid cells using subtractive hybridization and differential display. |journal=Int. J. Cancer |volume=71 |issue= 6 |pages= 1035-44 |year= 1997 |pmid= 9185708 |doi=  }}
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-*{{cite journal  | author=Yan C, Wang H, Boyd DD |title=KiSS-1 represses 92-kDa type IV collagenase expression by down-regulating NF-kappa B binding to the promoter as a consequence of Ikappa Balpha -induced block of p65/p50 nuclear translocation. |journal=J. Biol. Chem. |volume=276 |issue= 2 |pages= 1164-72 |year= 2001 |pmid= 11060311 |doi= 10.1074/jbc.M008681200 }}
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-*{{cite journal  | author=Kotani M, Detheux M, Vandenbogaerde A, ''et al.'' |title=The metastasis suppressor gene KiSS-1 encodes kisspeptins, the natural ligands of the orphan G protein-coupled receptor GPR54. |journal=J. Biol. Chem. |volume=276 |issue= 37 |pages= 34631-6 |year= 2001 |pmid= 11457843 |doi= 10.1074/jbc.M104847200 }}
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-*{{cite journal  | author=Sanchez-Carbayo M, Capodieci P, Cordon-Cardo C |title=Tumor suppressor role of KiSS-1 in bladder cancer: loss of KiSS-1 expression is associated with bladder cancer progression and clinical outcome. |journal=Am. J. Pathol. |volume=162 |issue= 2 |pages= 609-17 |year= 2003 |pmid= 12547718 |doi=  }}
-}}
-{{refend}}
-==External links==
+Coexpression imaging of KISS1 mRNA (using vector red) and steroid receptors determined that neurons that express KISS1 mRNA are targets for the action of sex steroids in both male and female mice.
-* {{MeshName|KISS1+protein,+human}}
-[[Category:Neuropeptides]]
+==See also==
-[[Category:Cell signaling]]
+* [[Neuropeptide VF precursor]]
+*[[KNDy neuron]]
+== References ==
+{{Reflist|33em}}
+== External links ==
+* {{MeshName|KISS1+protein,+human}}
-[[de:Kisspeptin]]
+{{Neuropeptides}}
-[[zh:亲吻促动素]]
+{{Peptidergics}}
-{{WH}}
+[[Category:Neuropeptides]]
-{{WikiDoc Sources}}
+[[Category:Cell signaling]]