Protein Kinase C-{alpha} Interaction with F0F1-ATPase Promotes F0F1-ATPase Activity and Reduces Energy Deficits in Inȷured Renal Cells [Bioenergetics]

January 27th, 2015 by Nowak, G., Bakajsova, D.

We have previously shown that active PKC-α maintains F0F1-ATPase activity whereas inactive PKC-α mutant (dnPKC-α) blocks recovery of F0F1-ATPase activity after injury in renal proximal tubules (RPTC). This study tested whether mitochondrial PKC-α interacts with and phosphorylates F0F1-ATPase. Wild-type PKC-α (wtPKC-α) and dnPKC-α were overexpressed in RPTC to increase their levels in mitochondria and RPTC were exposed to oxidant- or hypoxia-induced injury. Mitochondrial levels of γ subunit, but not α and β subunits, were decreased by injury and this event was associated with 54% inhibition of F0F1-ATPase activity. Overexpressing wtPKC-α blocked decreases in γ subunit levels, maintained F0F1-ATPase activity, and improved ATP levels after injury. Deletion of PKC-α decreased levels of α, β and γ subunits, decreased F0F1-ATPase activity, and hindered recovery of ATP content after RPTC injury. Mitochondrial PKC-α co-immunoprecipitated with α, β, and γ subunits of F0F1-ATPase. Association of PKC-α with these subunits decreased in injured RPTC overexpressing dnPKC-α. Immunocapture of F0F1-ATPase and immunoblotting with phospho-(Ser)PKC substrate antibody identified phosphorylation of serine in PKC consensus site on α or β and γ subunits. Overexpressing wtPKC-α increased phosphorylation and protein levels whereas deletion of PKC-α decreased protein levels of α, β and γ subunits of F0F1-ATPase in RPTC. Phosphoproteomics revealed phosphorylation of Ser146 on the γ subunit in response to wtPKC-α overexpression. We conclude that active PKC-α 1) prevents injury-induced decreases in levels of γ subunit of F0F1-ATPase, 2) interacts with α, β and γ subunits leading to increases in their phosphorylation, and 3) promotes recovery of F0F1-ATPase activity and ATP content after injury in RPTC.
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