Regulation of rat Na(+)-K(+)-ATPase activity by PKC is modulated by state of phosphorylation of Ser-943 by PKA.
We have previously shown that the rat Na(+)-K(+)-ATPase alpha 1-isoform is phosphorylated at Ser-943 by protein kinase A (PKA) and at Ser-23 by protein kinase C (PKC), which in both cases results in inhibition of enzyme activity. We now present evidence that suggests that the phosphorylation of Ser-943 by PKA modulates the response of Na(+)-K(+)-ATPase to PKC. Rat Na(+)-K(+)-ATPase alpha 1 or a mutant in which Ser-943 was changed to Ala-943 was stably expressed in COS cells. The inhibition of enzyme activity measured in response to treatment with the phorbol ester, phorbol 12,13-dibutyrate (PDBu; 10(-6) M), was significantly reduced in the cells expressing the Ala-943 mutant compared with that observed in cells expressing wild-type enzyme. In contrast, for cells expressing Na(+)-K(+)-ATPase alpha 1 in which Ser-943 was mutated to Asp-943, the effect of PDBu was slightly enhanced. The PDBu-induced inhibition was not mediated by activation of the adenosine 3',5'-cyclic monophosphate/PKA system and was not achieved via direct phosphorylation of Ser-943. Sp-5,6-DCI-cBIMPS, a specific PKA activator, increased the phosphorylation of Ser-943, and this was associated with an enhanced response to PDBu. Thus the effect of PKC on rat Na(+)-K(+)-ATPase alpha 1 is determined not only by the activity of PKC but also by the state of phosphorylation of Ser-943.
Cheng
X J
XJ
Department of Woman and Child Health, Karolinska Institute, Stockholm, Sweden.
Höög
J O
JO
Nairn
A C
AC
Greengard
P
P
Aperia
A
A
D000409:Alanine; D019943:Amino Acid Substitution; D000818:Animals; D019556:COS Cells; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D003600:Cytosol / Q000378:metabolism; D004004:Dichlororibofuranosylbenzimidazole / Q000031:analogs & derivatives / Q000494:pharmacology; D004789:Enzyme Activation; D006706:Homeostasis; D007527:Isoenzymes / Q000378:metabolism; D007700:Kinetics; D016297:Mutagenesis, Site-Directed; D015240:Phorbol 12,13-Dibutyrate / Q000494:pharmacology; D010766:Phosphorylation; D011493:Protein Kinase C / Q000378:metabolism*; D051381:Rats; D011994:Recombinant Proteins / Q000378:metabolism; D012694:Serine; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*; D013873:Thionucleotides / Q000494:pharmacology; D014162:Transfection
D007527:Isoenzymes; D011994:Recombinant Proteins; D013873:Thionucleotides; C071644:5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole-3',5'-monophosphorothioate; D005576:Colforsin; D015240:Phorbol 12,13-Dibutyrate; D012694:Serine; D004004:Dichlororibofuranosylbenzimidazole; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D011493:Protein Kinase C; D000254:Sodium-Potassium-Exchanging ATPase; D000409:Alanine