Protein kinase C-alpha inhibits the repair of oxidative phosphorylation after S-(1,2-dichlorovinyl)-L-cysteine injury in renal cells.
Previously, we showed that physiological functions of renal proximal tubular cells (RPTC) do not recover following S-(1,2-dichlorovinyl)-l-cysteine (DCVC)-induced injury. This study investigated the role of protein kinase C-alpha (PKC-alpha) in the lack of repair of mitochondrial function in DCVC-injured RPTC. After DCVC exposure, basal oxygen consumption (Qo(2)), uncoupled Qo(2), oligomycin-sensitive Qo(2), F(1)F(0)-ATPase activity, and ATP production decreased, respectively, to 59, 27, 27, 57, and 68% of controls. None of these functions recovered. Mitochondrial transmembrane potential decreased 53% after DCVC injury but recovered on day 4. PKC-alpha was activated 4.3- and 2.5-fold on days 2 and 4, respectively, of the recovery period. Inhibition of PKC-alpha activation (10 nM Go6976) did not block DCVC-induced decreases in mitochondrial functions but promoted the recovery of uncoupled Qo(2), oligomycin-sensitive Qo(2), F(1)F(0)-ATPase activity, and ATP production. Protein levels of the catalytic beta-subunit of F(1)F(0)-ATPase were not changed by DCVC or during the recovery period. Amino acid sequence analysis revealed that alpha-, beta-, and epsilon-subunits of F(1)F(0)-ATPase have PKC consensus motifs. Recombinant PKC-alpha phosphorylated the beta-subunit and decreased F(1)F(0)-ATPase activity in vitro. Serine but not threonine phosphorylation of the beta-subunit was increased during late recovery following DCVC injury, and inhibition of PKC-alpha activation decreased this phosphorylation. We conclude that during RPTC recovery following DCVC injury, 1). PKC-alpha activation decreases F(0)F(1)-ATPase activity, oxidative phosphorylation, and ATP production; 2). PKC-alpha phosphorylates the beta-subunit of F(1)F(0)-ATPase on serine residue; and 3). PKC-alpha does not mediate depolarization of RPTC mitochondria. This is the first report showing that PKC-alpha phosphorylates the catalytic subunit of F(1)F(0)-ATPase and that PKC-alpha plays an important role in regulating repair of mitochondrial function.
Department of Pharmaceutical Sciences, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA.
Xiuli
X
Liu
Malinda L
ML
Godwin
Grazyna
G
Nowak
D000818:Animals; D003545:Cysteine / Q000031:analogs & derivatives* / Q000633:toxicity*; D005260:Female; D007527:Isoenzymes; D007687:Kidney Tubules, Proximal / Q000166:cytology / Q000473:pathology / Q000502:physiology*; D008564:Membrane Potentials; D008928:Mitochondria / Q000473:pathology* / Q000502:physiology*; D010084:Oxidation-Reduction; D010101:Oxygen Consumption; D010766:Phosphorylation; D011493:Protein Kinase C / Q000494:pharmacology*; D051571:Protein Kinase C-alpha; D006180:Proton-Translocating ATPases / Q000494:pharmacology; D011817:Rabbits
D007527:Isoenzymes; C039961:S-(1,2-dichlorovinyl)cysteine; D011493:Protein Kinase C; D051571:Protein Kinase C-alpha; D006180:Proton-Translocating ATPases; D003545:Cysteine