pubmed.ncbi.nlm.nih.gov

Site-specific regulation of CA(V)2.2 channels by protein kinase C isozymes betaII and epsilon - PubMed

️Thu Jan 01 2009

Site-specific regulation of CA(V)2.2 channels by protein kinase C isozymes betaII and epsilon

S Rajagopal et al. Neuroscience. 2009.

Abstract

Ca(v)2.2 high voltage-gated calcium channels are regulated by phorbol-12-myristae, 13-acetate (PMA) via Ser/Thr protein kinase C (PKC) phosphorylation sites in the I-II linker and C-terminus of the alpha(1) 2.2 subunit. Here we show that PMA enhancement of Ca(v)2.2 currents expressed in Xenopus oocytes can be blocked by inhibitors of PKC betaII or PKC epsilon isozymes, as shown previously for Ca(v)2.3 currents, and that microinjection of PKC betaII or PKC epsilon isozymes in the oocytes expressing the WT Ca(v)2.2 channels increases the basal barium current (I(Ba)). The I-V plot shows a large increase in current amplitude with PKC betaII and PKC epsilon isozymes with only a small shift in the peak I(Ba) in the hyperpolarizing direction. The potentiation of Ca(v)2.2 currents by microinjection of PKC betaII and PKC epsilon isozymes was not altered by the inhibition of G proteins with GDPbetaS. The combination of isozyme specific inhibitors with previously generated Ser/Thr to Ala mutants of alpha(1) 2.2 subunit revealed that PKC betaII or PKC epsilon isozymes (but not PKC alpha or delta) can provide full enhancement through the stimulatory site (Thr-422) in the I-II linker but that PKC epsilon is better at decreasing channel activity through the inhibitory site Ser-425. The enhancing effect of PKC betaII or epsilon at Thr-422 is dominant over the inhibitory effect at Ser-425. Injected PKC betaII also enhances Ca(v)2.2 current when any of the potential stimulatory sites (Ser-1757, Ser-2108 and Ser-2132) are available in the C-terminus. PKC epsilon provides lesser enhancement with C-terminal sites and only with Ser-2108 and Ser-2132. Sites Ser-1757 and Ser-2132, but not Ser-2108, are dominant over the inhibitory site Ser-425. Collectively, these results reveal a hierarchy of regulatory sites in Ca(v)2.2 channels. Site-specific regulation by different PKC isozymes may allow graded levels of channel activation and susceptibility or resistance to subsequent stimulatory events.

PubMed Disclaimer

Cited by

PKCε contributes to lipid-induced insulin resistance through cross talk with p70S6K and through previously unknown regulators of insulin signaling.
Gassaway BM, Petersen MC, Surovtseva YV, Barber KW, Sheetz JB, Aerni HR, Merkel JS, Samuel VT, Shulman GI, Rinehart J. Gassaway BM, et al. Proc Natl Acad Sci U S A. 2018 Sep 18;115(38):E8996-E9005. doi: 10.1073/pnas.1804379115. Epub 2018 Sep 4. Proc Natl Acad Sci U S A. 2018. PMID: 30181290 Free PMC article.
"Slow" Voltage-Dependent Inactivation of CaV2.2 Calcium Channels Is Modulated by the PKC Activator Phorbol 12-Myristate 13-Acetate (PMA).
Zhu L, McDavid S, Currie KP. Zhu L, et al. PLoS One. 2015 Jul 29;10(7):e0134117. doi: 10.1371/journal.pone.0134117. eCollection 2015. PLoS One. 2015. PMID: 26222492 Free PMC article.
Mining recent brain proteomic databases for ion channel phosphosite nuggets.
Cerda O, Baek JH, Trimmer JS. Cerda O, et al. J Gen Physiol. 2011 Jan;137(1):3-16. doi: 10.1085/jgp.201010555. Epub 2010 Dec 13. J Gen Physiol. 2011. PMID: 21149544 Free PMC article. Review.
Contribution of protein kinase Cα in the stimulation of insulin by the down-regulation of Cavβ subunits.
Rajagopal S, Fields BL, Kamatchi GL. Rajagopal S, et al. Endocrine. 2014 Nov;47(2):463-71. doi: 10.1007/s12020-013-0149-y. Epub 2014 Jan 23. Endocrine. 2014. PMID: 24452871 Free PMC article.
Regulation of Ca(V)2 calcium channels by G protein coupled receptors.
Zamponi GW, Currie KP. Zamponi GW, et al. Biochim Biophys Acta. 2013 Jul;1828(7):1629-43. doi: 10.1016/j.bbamem.2012.10.004. Epub 2012 Oct 12. Biochim Biophys Acta. 2013. PMID: 23063655 Free PMC article. Review.

Site-specific regulation of CA(V)2.2 channels by protein kinase C isozymes betaII and epsilon - PubMed