This gene encodes an alpha-1 subunit of a voltage-dependent calcium channel. Calcium channels mediate the influx of calcium ions into the cell upon membrane polarization.[3]
The alpha-1 subunit consists of 24 transmembrane segments and forms the pore through which ions pass into the cell. The calcium channel consists of a complex of alpha-1, alpha-2/delta and beta subunits in a 1:1:1 ratio. The S3-S4 linkers of Cav1.2 determine the gating phenotype and modulated gating kinetics of the channel.[4] Cav1.2 is widely expressed in the smooth muscle, pancreatic cells, fibroblasts, and neurons.[5][6] However, it is particularly important and well known for its expression in the heart where it mediates L-type currents, which causes calcium-induced calcium release from the ER Stores via ryanodine receptors. It depolarizes at -30mV and helps define the shape of the action potential in cardiac and smooth muscle.[4] The protein encoded by this gene binds to and is inhibited by dihydropyridine.[7] In the arteries of the brain, high levels of calcium in mitochondria elevates activity of nuclear factor kappa B NF-κB and transcription of CACNA1c and functional Cav1.2 expression increases.[8] Cav1.2 also regulates levels of osteoprotegerin.[9]
The activity of CaV1.2 channels is tightly regulated by the Ca2+ signals they produce. An increase in intracellular Ca2+ concentration implicated in Cav1.2 facilitation, a form of positive feedback called Ca2+-dependent facilitation, that amplifies Ca2+ influx. In addition, increasing influx intracellular Ca2+ concentration has implicated to exert the opposite effect Ca2+ dependent inactivation.[11] These activation and inactivation mechanisms both involve Ca2+ binding to calmodulin (CaM) in the IQ domain in the C-terminal tail of these channels.[12] Cav1.2 channels are arranged in cluster of eight, on average, in the cell membrane. When calcium ions bind to calmodulin, which in turn binds to a Cav1.2 channel, it allows the Cav1.2 channels within a cluster to interact with each other.[13] This results in channels working cooperatively when they open at the same time to allow more calcium ions to enter and then close together to allow the cell to relax.[13]
Clinical significance
Mutation in the CACNA1C gene, the single-nucleotide polymorphism located in the third intron of the Cav1.2 gene,[14] are associated with a variant of Long QT syndrome called Timothy's syndrome[15] and also with Brugada syndrome.[16] Large-scale genetic analyses have shown the possibility that CACNA1C is associated with bipolar disorder[17] and subsequently also with schizophrenia.[18][19][20] Also, a CACNA1C risk allele has been associated to a disruption in brain connectivity in patients with bipolar disorder, while not or only to a minor degree, in their unaffected relatives or healthy controls.[21]
Interactive pathway map
Click on genes, proteins and metabolites below to link to respective Wikipedia articles.[§ 1]
↑Lacerda AE, Kim HS, Ruth P, Perez-Reyes E, Flockerzi V, Hofmann F, Birnbaumer L, Brown AM (Aug 1991). "Normalization of current kinetics by interaction between the alpha 1 and beta subunits of the skeletal muscle dihydropyridine-sensitive Ca2+ channel". Nature. 352 (6335): 527–30. doi:10.1038/352527a0. PMID1650913.
↑Catterall WA, Perez-Reyes E, Snutch TP, Striessnig J (Dec 2005). "International Union of Pharmacology. XLVIII. Nomenclature and structure-function relationships of voltage-gated calcium channels". Pharmacological Reviews. 57 (4): 411–25. doi:10.1124/pr.57.4.5. PMID16382099.
↑Bergh JJ, Xu Y, Farach-Carson MC (Jan 2004). "Osteoprotegerin expression and secretion are regulated by calcium influx through the L-type voltage-sensitive calcium channel". Endocrinology. 145 (1): 426–36. doi:10.1210/en.2003-0319. PMID14525906.
↑Radua J, Surguladze SA, Marshall N, Walshe M, Bramon E, Collier DA, Prata DP, Murray RM, McDonald C (May 2013). "The impact of CACNA1C allelic variation on effective connectivity during emotional processing in bipolar disorder". Molecular Psychiatry. 18 (5): 526–7. doi:10.1038/mp.2012.61. PMID22614292.
Further reading
Kempton MJ, Ruberto G, Vassos E, Tatarelli R, Girardi P, Collier D, Frangou S (Dec 2009). "Effects of the CACNA1C risk allele for bipolar disorder on cerebral gray matter volume in healthy individuals". The American Journal of Psychiatry. 166 (12): 1413–4. doi:10.1176/appi.ajp.2009.09050680. PMID19952088.
Powers PA, Gregg RG, Hogan K (Sep 1992). "Linkage mapping of the human gene for the alpha 1 subunit of the cardiac DHP-sensitive Ca2+ channel (CACNL1A1) to chromosome 12p13.2-pter using a dinucleotide repeat". Genomics. 14 (1): 206–7. doi:10.1016/S0888-7543(05)80312-X. PMID1330882.
Sun W, McPherson JD, Hoang DQ, Wasmuth JJ, Evans GA, Montal M (Dec 1992). "Mapping of a human brain voltage-gated calcium channel to human chromosome 12p13-pter". Genomics. 14 (4): 1092–4. doi:10.1016/S0888-7543(05)80135-1. PMID1335957.
Powers PA, Gregg RG, Lalley PA, Liao M, Hogan K (Jul 1991). "Assignment of the human gene for the alpha 1 subunit of the cardiac DHP-sensitive Ca2+ channel (CCHL1A1) to chromosome 12p12-pter". Genomics. 10 (3): 835–9. doi:10.1016/0888-7543(91)90471-P. PMID1653763.
Perez-Reyes E, Wei XY, Castellano A, Birnbaumer L (Nov 1990). "Molecular diversity of L-type calcium channels. Evidence for alternative splicing of the transcripts of three non-allelic genes". The Journal of Biological Chemistry. 265 (33): 20430–6. PMID2173707.
Soldatov NM, Bouron A, Reuter H (May 1995). "Different voltage-dependent inhibition by dihydropyridines of human Ca2+ channel splice variants". The Journal of Biological Chemistry. 270 (18): 10540–3. doi:10.1074/jbc.270.18.10540. PMID7737988.
Tang S, Mikala G, Bahinski A, Yatani A, Varadi G, Schwartz A (Jun 1993). "Molecular localization of ion selectivity sites within the pore of a human L-type cardiac calcium channel". The Journal of Biological Chemistry. 268 (18): 13026–9. PMID8099908.
Perets T, Blumenstein Y, Shistik E, Lotan I, Dascal N (Apr 1996). "A potential site of functional modulation by protein kinase A in the cardiac Ca2+ channel alpha 1C subunit". FEBS Letters. 384 (2): 189–92. doi:10.1016/0014-5793(96)00303-1. PMID8612821.
Andersson B, Wentland MA, Ricafrente JY, Liu W, Gibbs RA (Apr 1996). "A "double adaptor" method for improved shotgun library construction". Analytical Biochemistry. 236 (1): 107–13. doi:10.1006/abio.1996.0138. PMID8619474.
Soldatov NM, Zühlke RD, Bouron A, Reuter H (Feb 1997). "Molecular structures involved in L-type calcium channel inactivation. Role of the carboxyl-terminal region encoded by exons 40-42 in alpha1C subunit in the kinetics and Ca2+ dependence of inactivation". The Journal of Biological Chemistry. 272 (6): 3560–6. doi:10.1074/jbc.272.6.3560. PMID9013606.
Klöckner U, Mikala G, Eisfeld J, Iles DE, Strobeck M, Mershon JL, Schwartz A, Varadi G (Mar 1997). "Properties of three COOH-terminal splice variants of a human cardiac L-type Ca2+-channel alpha1-subunit". The American Journal of Physiology. 272 (3 Pt 2): H1372–81. PMID9087614.
Gao T, Yatani A, Dell'Acqua ML, Sako H, Green SA, Dascal N, Scott JD, Hosey MM (Jul 1997). "cAMP-dependent regulation of cardiac L-type Ca2+ channels requires membrane targeting of PKA and phosphorylation of channel subunits". Neuron. 19 (1): 185–96. doi:10.1016/S0896-6273(00)80358-X. PMID9247274.
Zühlke RD, Bouron A, Soldatov NM, Reuter H (May 1998). "Ca2+ channel sensitivity towards the blocker isradipine is affected by alternative splicing of the human alpha1C subunit gene". FEBS Letters. 427 (2): 220–4. doi:10.1016/S0014-5793(98)00425-6. PMID9607315.
Meyers MB, Puri TS, Chien AJ, Gao T, Hsu PH, Hosey MM, Fishman GI (Jul 1998). "Sorcin associates with the pore-forming subunit of voltage-dependent L-type Ca2+ channels". The Journal of Biological Chemistry. 273 (30): 18930–5. doi:10.1074/jbc.273.30.18930. PMID9668070.
Liu WS, Soldatov NM, Gustavsson I, Chowdhary BP (1999). "Fiber-FISH analysis of the 3'-terminal region of the human L-type Ca2+ channel alpha 1C subunit gene". Hereditas. 129 (2): 169–75. doi:10.1111/j.1601-5223.1998.00169.x. PMID10022083.