| First Author | Katchman A | Year | 2017 |
| Journal | Proc Natl Acad Sci U S A | Volume | 114 |
| Issue | 34 | Pages | 9194-9199 |
| PubMed ID | 28784807 | Mgi Jnum | J:244176 |
| Mgi Id | MGI:5912955 | Doi | 10.1073/pnas.1706054114 |
| Citation | Katchman A, et al. (2017) Proteolytic cleavage and PKA phosphorylation of alpha1C subunit are not required for adrenergic regulation of CaV1.2 in the heart. Proc Natl Acad Sci U S A 114(34):9194-9199 |
| abstractText | Calcium influx through the voltage-dependent L-type calcium channel (CaV1.2) rapidly increases in the heart during "fight or flight" through activation of the beta-adrenergic and protein kinase A (PKA) signaling pathway. The precise molecular mechanisms of beta-adrenergic activation of cardiac CaV1.2, however, are incompletely known, but are presumed to require phosphorylation of residues in alpha1C and C-terminal proteolytic cleavage of the alpha1C subunit. We generated transgenic mice expressing an alpha1C with alanine substitutions of all conserved serine or threonine, which is predicted to be a potential PKA phosphorylation site by at least one prediction tool, while sparing the residues previously shown to be phosphorylated but shown individually not to be required for beta-adrenergic regulation of CaV1.2 current (17-mutant). A second line included these 17 putative sites plus the five previously identified phosphoregulatory sites (22-mutant), thus allowing us to query whether regulation requires their contribution in combination. We determined that acute beta-adrenergic regulation does not require any combination of potential PKA phosphorylation sites conserved in human, guinea pig, rabbit, rat, and mouse alpha1C subunits. We separately generated transgenic mice with inducible expression of proteolytic-resistant alpha1C Prevention of C-terminal cleavage did not alter beta-adrenergic stimulation of CaV1.2 in the heart. These studies definitively rule out a role for all conserved consensus PKA phosphorylation sites in alpha1C in beta-adrenergic stimulation of CaV1.2, and show that phosphoregulatory sites on alpha1C are not redundant and do not each fractionally contribute to the net stimulatory effect of beta-adrenergic stimulation. Further, proteolytic cleavage of alpha1C is not required for beta-adrenergic stimulation of CaV1.2. |
