A novel Ca(V)1.2 N terminus expressed in smooth muscle cells of resistance size arteries modifies channel regulation by auxiliary subunits.
Voltage-dependent L-type Ca(2+) (Ca(V)1.2) channels are the principal Ca(2+) entry pathway in arterial myocytes. Ca(V)1.2 channels regulate multiple vascular functions and are implicated in the pathogenesis of human disease, including hypertension. However, the molecular identity of Ca(V)1.2 channels expressed in myocytes of myogenic arteries that regulate vascular pressure and blood flow is unknown. Here, we cloned Ca(V)1.2 subunits from resistance size cerebral arteries and demonstrate that myocytes contain a novel, cysteine rich N terminus that is derived from exon 1 (termed "exon 1c"), which is located within CACNA1C, the Ca(V)1.2 gene. Quantitative PCR revealed that exon 1c was predominant in arterial myocytes, but rare in cardiac myocytes, where exon 1a prevailed. When co-expressed with alpha(2)delta subunits, Ca(V)1.2 channels containing the novel exon 1c-derived N terminus exhibited: 1) smaller whole cell current density, 2) more negative voltages of half activation (V(1/2,act)) and half-inactivation (V(1/2,inact)), and 3) reduced plasma membrane insertion, when compared with channels containing exon 1b. beta(1b) and beta(2a) subunits caused negative shifts in the V(1/2,act) and V(1/2,inact) of exon 1b-containing Ca(V)1.2alpha(1)/alpha(2)delta currents that were larger than those in exon 1c-containing Ca(V)1.2alpha(1)/alpha(2)delta currents. In contrast, beta(3) similarly shifted V(1/2,act) and V(1/2,inact) of currents generated by exon 1b- and exon 1c-containing channels. beta subunits isoform-dependent differences in current inactivation rates were also detected between N-terminal variants. Data indicate that through novel alternative splicing at exon 1, the Ca(V)1.2 N terminus modifies regulation by auxiliary subunits. The novel exon 1c should generate distinct voltage-dependent Ca(2+) entry in arterial myocytes, resulting in tissue-specific Ca(2+) signaling.
Cheng
Xiaoyang
X
Department of Physiology, University of Tennessee Health Science Center, Memphis, Tennessee 38163, USA.
Liu
Jianxi
J
Asuncion-Chin
Maria
M
Blaskova
Eva
E
Bannister
John P
JP
Dopico
Alejandro M
AM
Jaggar
Jonathan H
JH
D000818:Animals; D001158:Arteries / Q000378:metabolism*; D001483:Base Sequence; D019556:COS Cells; D020746:Calcium Channels, L-Type / Q000737:chemistry* / Q000502:physiology; D002522:Chlorocebus aethiops; D004594:Electrophysiology / Q000379:methods; D006801:Humans; D008969:Molecular Sequence Data; D032342:Muscle Cells / Q000378:metabolism; D009206:Myocardium / Q000378:metabolism; D017434:Protein Structure, Tertiary; D051381:Rats; D017207:Rats, Sprague-Dawley; D012689:Sequence Homology, Nucleic Acid; D015398:Signal Transduction
D020746:Calcium Channels, L-Type; C419385:L-type calcium channel alpha(1C)
Neuron. 2000 Jan;25(1):177-90
10707982
Eur J Neurosci. 2000 Mar;12(3):894-902
10762319
Biochemistry. 2000 Apr 25;39(16):4649-57
10769120
J Physiol. 2000 Jun 1;525 Pt 2:377-90
10835041
Am J Physiol Cell Physiol. 2001 Aug;281(2):C439-48
11443043
Am J Physiol Cell Physiol. 2002 Sep;283(3):C1001-8
12176756
Biochem Biophys Res Commun. 2003 Feb 28;302(1):23-8
12593842
Biophys J. 2003 May;84(5):3007-21
12719232
Am J Physiol Heart Circ Physiol. 2003 Jul;285(1):H97-103
12649078
Curr Opin Neurobiol. 2003 Jun;13(3):298-307
12850214
J Biol Chem. 2003 Aug 1;278(31):29231-9
12721298
EMBO J. 2003 Nov 17;22(22):6027-34
14609949
J Bioenerg Biomembr. 2003 Dec;35(6):639-47
15000524
Physiol Genomics. 2004 Apr 13;17(2):183-200
14762176
J Neurosci. 2004 Sep 22;24(38):8322-32
15385615
FEBS Lett. 2004 Oct 8;576(1-2):21-6
15474003
J Biol Chem. 2004 Oct 22;279(43):44335-43
15299022
Nature. 1989 Jul 20;340(6230):230-3
2474130
Am J Physiol. 1990 Jul;259(1 Pt 1):C3-18
2164782
FEBS Lett. 1990 Sep 3;269(2):409-12
2169433
J Biol Chem. 1990 Oct 15;265(29):17786-91
2170396
Neuron. 1991 Jul;7(1):45-57
1648941
FEBS Lett. 1991 Oct 21;291(2):253-8
1657644
J Biol Chem. 1992 Jan 25;267(3):1792-7
1370480
EMBO J. 1992 Mar;11(3):885-90
1312465
Proc Natl Acad Sci U S A. 1992 May 15;89(10):4628-32
1316612
J Biol Chem. 1993 Feb 15;268(5):3450-5
7679112
J Cell Biol. 1993 Nov;123(4):949-62
8227151
J Neurosci. 1997 Sep 15;17(18):6884-91
9278523
Kidney Blood Press Res. 1997;20(6):355-71
9453447
J Biol Chem. 1998 Sep 4;273(36):23590-7
9722599
Physiol Rev. 1999 Apr;79(2):387-423
10221985
J Physiol. 1999 Jun 1;517 ( Pt 2):353-68
10332087
Biochim Biophys Acta. 1999 Aug 12;1451(1):1-16
10446384
Cell Calcium. 2005 Apr;37(4):301-9
15755491
J Biol Chem. 2005 Apr 1;280(13):12474-85
15671035
Cardiovasc Res. 2005 Nov 1;68(2):197-203
16051206
Circ Res. 2005 Oct 14;97(8):805-12
16166559
Pharmacol Rev. 2005 Dec;57(4):411-25
16382099
Vascul Pharmacol. 2006 Mar;44(3):131-42
16427812
Curr Pharm Des. 2006;12(4):443-57
16472138
Proc Natl Acad Sci U S A. 2006 Nov 7;103(45):17024-9
17071743
Cell Calcium. 2007 May;41(5):417-28
16979758
J Mol Cell Cardiol. 2000 Jun;32(6):973-84
10888251
Biophys J. 2000 Aug;79(2):731-46
10920007
Nat Rev Mol Cell Biol. 2000 Oct;1(1):11-21
11413485
Biophys J. 2001 Jul;81(1):89-96
11423397