Protein kinase C-mediated regulation of the renal Na(+)/dicarboxylate cotransporter, NaDC-1.
The Na(+)/dicarboxylate cotransporter of the renal proximal tubule, NaDC-1, reabsorbs Krebs cycle intermediates, such as succinate and citrate, from the tubular filtrate. Although long-term regulation of this transporter by chronic metabolic acidosis and K(+) deficiency is well documented, there is no information on acute regulation of NaDC-1. In the present study, the transport of succinate in Xenopus oocytes expressing NaDC-1 was inhibited up to 95% by two activators of protein kinase C, phorbol 12-myristate, 13-acetate (PMA) and sn-1, 2-dioctanoylglycerol (DOG). Activation of protein kinase A had no effect on NaDC-1 activity. The inhibition of NaDC-1 transport by PMA was dose-dependent, and could be prevented by incubation of the oocytes with staurosporine. Mutations of the two consensus protein kinase C phosphorylation sites in NaDC-1 did not affect inhibition by PMA. The inhibitory effects of PMA were partially prevented by cytochalasin D, which disrupts microfilaments and endocytosis. PMA treatment was also associated with a decrease of approximately 30% in the amount of NaDC-1 protein found on the plasma membrane. We conclude that the inhibition of NaDC-1 transport activity by PMA occurs by a combination of endocytosis and inhibition of transport activity.
Pajor
A M
AM
Department of Physiology and Biophysics, University of Texas Medical Branch, Galveston, TX 77555-0641, USA. ampajor@utmb.edu
Sun
N
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D000818:Animals; D001483:Base Sequence; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D003078:Colchicine / Q000494:pharmacology; D015638:Cytochalasin D / Q000494:pharmacology; D017931:DNA Primers / Q000235:genetics; D029382:Dicarboxylic Acid Transporters; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D066298:In Vitro Techniques; D007687:Kidney Tubules, Proximal / Q000378:metabolism*; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D016297:Mutagenesis, Site-Directed; D009865:Oocytes / Q000187:drug effects / Q000378:metabolism; D029363:Organic Anion Transporters, Sodium-Dependent; D011493:Protein Kinase C / Q000378:metabolism*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D027981:Symporters; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014982:Xenopus laevis
D002352:Carrier Proteins; D017931:DNA Primers; D029382:Dicarboxylic Acid Transporters; D004791:Enzyme Inhibitors; D008565:Membrane Proteins; D029363:Organic Anion Transporters, Sodium-Dependent; D011994:Recombinant Proteins; C092524:SLC13A2 protein, human; D027981:Symporters; D015638:Cytochalasin D; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate; D003078:Colchicine