This gene encodes the MT2protein, one of two high-affinity forms of a receptor for melatonin, the primary hormone secreted by the pineal gland. This gene product is an integral membrane protein that is a G-protein coupled, 7-transmembrane receptor. It is found primarily in the retina and brain; however, this detection requires RT-PCR. It is thought to participate in light-dependent functions in the retina and may be involved in the neurobiological effects of melatonin.[1] Besides the brain and retina this receptor is expressed on the bone forming cells where it regulates their function in depositing bone. [3]
Clinical significance
Several studies have identified MTNR1B receptor mutations that are associated with increased average blood sugar level and around a 20 percent elevated risk of developing type 2 diabetes.[4][5][6] MTNR1B mRNA is expressed in human islets, and immunocytochemistry confirms that it is primarily localized in beta cells in islets.[5]
Ligands
The following MT2R ligands have selectivity over MT1R:
↑ 5.05.1Prokopenko I, Langenberg C, Florez JC, Saxena R, Soranzo N, Thorleifsson G, et al. (Jan 2009). "Variants in MTNR1B influence fasting glucose levels". Nature Genetics. 41 (1): 77–81. doi:10.1038/ng.290. PMC2682768. PMID19060907.; Lyssenko V, Nagorny CL, Erdos MR, Wierup N, Jonsson A, Spégel P, et al. (Jan 2009). "Common variant in MTNR1B associated with increased risk of type 2 diabetes and impaired early insulin secretion". Nature Genetics. 41 (1): 82–88. doi:10.1038/ng.288. PMID19060908.; Bouatia-Naji N, Bonnefond A, Cavalcanti-Proença C, Sparsø T, Holmkvist J, Marchand M, et al. (Jan 2009). "A variant near MTNR1B is associated with increased fasting plasma glucose levels and type 2 diabetes risk". Nature Genetics. 41 (1): 89–94. doi:10.1038/ng.277. PMID19060909.
↑Rivara S, Lodola A, Mor M, Bedini A, Spadoni G, Lucini V, Pannacci M, Fraschini F, Scaglione F, Sanchez RO, Gobbi G, Tarzia G (Dec 2007). "N-(substituted-anilinoethyl)amides: design, synthesis, and pharmacological characterization of a new class of melatonin receptor ligands". Journal of Medicinal Chemistry. 50 (26): 6618–26. doi:10.1021/jm700957j. PMID18052314.
↑Bedini A, Spadoni G, Gatti G, Lucarini S, Tarzia G, Rivara S, Lorenzi S, Lodola A, Mor M, Lucini V, Pannacci M, Scaglione F (Dec 2006). "Design and synthesis of N-(3,3-diphenylpropenyl)alkanamides as a novel class of high-affinity MT2-selective melatonin receptor ligands". Journal of Medicinal Chemistry. 49 (25): 7393–403. doi:10.1021/jm060850a. PMID17149869.
Reppert SM, Weaver DR, Ebisawa T, Mahle CD, Kolakowski LF (May 1996). "Cloning of a melatonin-related receptor from human pituitary". FEBS Letters. 386 (2–3): 219–24. doi:10.1016/0014-5793(96)00437-1. PMID8647286.
Niles LP, Wang J, Shen L, Lobb DK, Younglai EV (Oct 1999). "Melatonin receptor mRNA expression in human granulosa cells". Molecular and Cellular Endocrinology. 156 (1–2): 107–10. doi:10.1016/S0303-7207(99)00135-5. PMID10612428.
Ebisawa T, Uchiyama M, Kajimura N, Kamei Y, Shibui K, Kim K, Kudo Y, Iwase T, Sugishita M, Jodoi T, Ikeda M, Ozeki Y, Watanabe T, Sekimoto M, Katoh M, Yamada N, Toyoshima R, Okawa M, Takahashi K, Yamauchi T (Feb 2000). "Genetic polymorphisms of human melatonin 1b receptor gene in circadian rhythm sleep disorders and controls". Neuroscience Letters. 280 (1): 29–32. doi:10.1016/S0304-3940(99)00981-7. PMID10696804.
Roy D, Angelini NL, Fujieda H, Brown GM, Belsham DD (Nov 2001). "Cyclical regulation of GnRH gene expression in GT1-7 GnRH-secreting neurons by melatonin". Endocrinology. 142 (11): 4711–20. doi:10.1210/en.142.11.4711. PMID11606436.
Ayoub MA, Couturier C, Lucas-Meunier E, Angers S, Fossier P, Bouvier M, Jockers R (Jun 2002). "Monitoring of ligand-independent dimerization and ligand-induced conformational changes of melatonin receptors in living cells by bioluminescence resonance energy transfer". The Journal of Biological Chemistry. 277 (24): 21522–8. doi:10.1074/jbc.M200729200. PMID11940583.
Yuan L, Collins AR, Dai J, Dubocovich ML, Hill SM (Jun 2002). "MT(1) melatonin receptor overexpression enhances the growth suppressive effect of melatonin in human breast cancer cells". Molecular and Cellular Endocrinology. 192 (1–2): 147–56. doi:10.1016/S0303-7207(02)00029-1. PMID12088876.
Slominski A, Pisarchik A, Zbytek B, Tobin DJ, Kauser S, Wortsman J (Jul 2003). "Functional activity of serotoninergic and melatoninergic systems expressed in the skin". Journal of Cellular Physiology. 196 (1): 144–53. doi:10.1002/jcp.10287. PMID12767050.
Ayoub MA, Levoye A, Delagrange P, Jockers R (Aug 2004). "Preferential formation of MT1/MT2 melatonin receptor heterodimers with distinct ligand interaction properties compared with MT2 homodimers". Molecular Pharmacology. 66 (2): 312–21. doi:10.1124/mol.104.000398. PMID15266022.
Mazna P, Berka K, Jelinkova I, Balik A, Svoboda P, Obsilova V, Obsil T, Teisinger J (Jul 2005). "Ligand binding to the human MT2 melatonin receptor: the role of residues in transmembrane domains 3, 6, and 7". Biochemical and Biophysical Research Communications. 332 (3): 726–34. doi:10.1016/j.bbrc.2005.05.017. PMID15913560.
Ha E, Choe BK, Jung KH, Yoon SH, Park HJ, Park HK, Yim SV, Chung JH, Bae HS, Nam M, Baik HH, Hong SJ (Sep 2005). "Positive relationship between melatonin receptor type 1B polymorphism and rheumatoid factor in rheumatoid arthritis patients in the Korean population". Journal of Pineal Research. 39 (2): 201–5. doi:10.1111/j.1600-079X.2005.00237.x. PMID16098099.
Savaskan E, Jockers R, Ayoub M, Angeloni D, Fraschini F, Flammer J, Eckert A, Müller-Spahn F, Meyer P (Feb 2007). "The MT2 melatonin receptor subtype is present in human retina and decreases in Alzheimer's disease". Current Alzheimer Research. 4 (1): 47–51. doi:10.2174/156720507779939823. PMID17316165.
Suzuki S, Masui Y, Ohnuki M, Miyakoda G, Mori T, Nakajima K, Sato M (Apr 2007). "Induction of metallothionein synthesis by cilostazol in mice and in human cultured neuronal cell lines". Biological & Pharmaceutical Bulletin. 30 (4): 791–4. doi:10.1248/bpb.30.791. PMID17409522.
Qiu XS, Tang NL, Yeung HY, Lee KM, Hung VW, Ng BK, Ma SL, Kwok RH, Qin L, Qiu Y, Cheng JC (Jul 2007). "Melatonin receptor 1B (MTNR1B) gene polymorphism is associated with the occurrence of adolescent idiopathic scoliosis". Spine. 32 (16): 1748–53. doi:10.1097/BRS.0b013e3180b9f0ff. PMID17632395.
External links
"Melatonin Receptors: MT2". IUPHAR Database of Receptors and Ion Channels. International Union of Basic and Clinical Pharmacology.