Protein kinase C isoform antagonism controls BNaC2 (ASIC1) function.
We explored the involvement of protein kinase C (PKC) and its isoforms in the regulation of BNaC2. Reverse transcriptase PCR evaluation of PKC isoform expression at the level of mRNA revealed the presence of alpha and epsilon/epsilon' in all glioma cell lines analyzed; most, but not all cell lines expressed delta and zeta. No messages were found for the betaI and betaII isotypes of PKC in the tumor cells. Normal astrocytes expressed beta but not gamma. The essential features of these results were confirmed at the protein level by Western analysis. This disproportionate pattern of PKC isoform expression in glioma cell lines was further echoed in the functional effects of these PKC isoforms on BNaC2 activity in bilayers. PKC holoenzyme or the combination of PKCbetaI and PKCbetaII isoforms inhibited BNaC2. Neither PKCepsilon nor PKCzeta or their combination had any effect on BNaC2 activity in bilayers. The inhibitory effect of the PKCbetaI and PKCbetaII mixture on BNaC2 activity was abolished by a 5-fold excess of a PKCepsilon and PKCzeta combination. PKC holoenzymes, PKCbetaI, PKCbetaII, PKCdelta, PKCepsilon, and PKCzeta phosphorylated BNaC2 in vitro. In patch clamp experiments, the combination of PKCbetaI and PKCbetaII inhibited the basally activated inward Na(+) conductance. The variable expression of the PKC isotypes and their functional antagonism in regulating BNaC2 activity support the idea that the participation of multiple PKC isotypes contributes to the overall activity of BNaC2.
Berdiev
Bakhrom K
BK
Department of Physiology and Biophysics, University of Alabama at Birmingham, Birmingham, Alabama 35294, USA.
Xia
Jiazeng
J
Jovov
Biljana
B
Markert
James M
JM
Mapstone
Timothy B
TB
Gillespie
G Yancey
GY
Fuller
Catherine M
CM
Bubien
James K
JK
Benos
Dale J
DJ
D062565:Acid Sensing Ion Channels; D000818:Animals; D001483:Base Sequence; D015153:Blotting, Western; D002478:Cells, Cultured; D017931:DNA Primers; D006801:Humans; D007527:Isoenzymes / Q000037:antagonists & inhibitors* / Q000378:metabolism; D008051:Lipid Bilayers; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins / Q000502:physiology*; D010766:Phosphorylation; D011493:Protein Kinase C / Q000037:antagonists & inhibitors* / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012964:Sodium / Q000378:metabolism; D015222:Sodium Channels / Q000502:physiology*; D014981:Xenopus
C568266:ASIC1 protein, human; D062565:Acid Sensing Ion Channels; D017931:DNA Primers; D007527:Isoenzymes; D008051:Lipid Bilayers; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D015222:Sodium Channels; D012964:Sodium; D011493:Protein Kinase C