Regulation of the Na,K-ATPase in MDCK cells by prostaglandin E1: a role for calcium as well as cAMP.
Prostaglandins (PGs) play a significant role in the regulation of sodium reabsorption by the kidney, in addition to accumulating during inflammation as well as in several solid tumors. Previously, we presented evidence indicating that prostaglandin E(1) (PGE(1)), a supplement in the serum-free medium for MDCK cells, increases the activity of the Na,K-ATPase in MDCK cells, in addition to its growth stimulatory effect [J. Cell. Physiol. 151 (1992) 337]. This report defines the molecular mechanisms, and signaling pathways responsible for the increased Na,K-ATPase activity. Our results indicate that the increased activity of the Na,K-ATPase in MDCK monolayers treated with either PGE(1) or 8Bromocyclic AMP (8Br-cAMP) can be attributed to an increase in the rate of biosynthesis of the Na,K-ATPase, and an increase in the levels of Na,K-ATPase alpha and beta subunit mRNAs. As beta subunit mRNA increased to a larger extent than alpha subunit mRNA, transient transfection studies were conducted using a human beta1 promoter/luciferase construct [Nucleic Acids Res. 21 (1993) 2619]. While an 8Br-cAMP stimulation was observed (suggesting the involvement of cAMP), our results also suggest that the observed PGE(1) stimulation could be explained by the involvement of Ca(2+) as well protein kinase C (PKC). Consistent with the involvement of Ca(2+), TMB-8 (which inhibits Ca(2+) efflux from intracellular stores) inhibited the PGE(1) stimulation. Moreover, PGE(1) was observed to stimulate the translocation of PKC beta1 from the soluble to the particulate fraction. The translocation of PKC, the PGE(1) stimulation of transcription, and the PGE(1)-mediated increase in the beta subunit mRNA level were all inhibited by the PKC inhibitor Gö6989. These results can be explained by the involvement of two classes of cell surface receptors in mediating the PGE(1) stimulation, including the EP1subtype (which activates phospholipase C), as well as the EP2 subtype (which activates adenylate cyclase).
Biochemistry Department, School of Medicine and Biomedical Sciences, State University of New York at Buffalo, Buffalo, NY 14214, USA. biochtau@buffalo.edu
Mary
M
Taub
Maryanne
M
Borsick
Janet
J
Geisel
Keikantse
K
Matlhagela
Trivikram
T
Rajkhowa
Cheryl
C
Allen
D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000494:pharmacology; D000527:Alprostadil / Q000378:metabolism* / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology; D002460:Cell Line; D000242:Cyclic AMP / Q000378:metabolism*; D004285:Dogs; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism; D005707:Gallic Acid / Q000031:analogs & derivatives* / Q000494:pharmacology; D007684:Kidney Tubules / Q000166:cytology / Q000378:metabolism; D011493:Protein Kinase C / Q000187:drug effects / Q000378:metabolism; D021122:Protein Subunits / Q000235:genetics; D021381:Protein Transport / Q000187:drug effects / Q000235:genetics; D012333:RNA, Messenger / Q000187:drug effects / Q000378:metabolism; D018078:Receptors, Prostaglandin E / Q000187:drug effects / Q000378:metabolism; D058306:Receptors, Prostaglandin E, EP1 Subtype; D058307:Receptors, Prostaglandin E, EP2 Subtype; D012964:Sodium / Q000378:metabolism; D000254:Sodium-Potassium-Exchanging ATPase / Q000096:biosynthesis* / Q000187:drug effects; D015533:Transcriptional Activation / Q000187:drug effects / Q000235:genetics; D015854:Up-Regulation / Q000187:drug effects / Q000235:genetics; D014882:Water-Electrolyte Balance / Q000187:drug effects / Q000502:physiology
D004791:Enzyme Inhibitors; C545635:PTGER1 protein, human; C545644:PTGER2 protein, human; D021122:Protein Subunits; D012333:RNA, Messenger; D018078:Receptors, Prostaglandin E; D058306:Receptors, Prostaglandin E, EP1 Subtype; D058307:Receptors, Prostaglandin E, EP2 Subtype; D015124:8-Bromo Cyclic Adenosine Monophosphate; C006014:8-(N,N-diethylamino)octyl-3,4,5-trimethoxybenzoate; D005707:Gallic Acid; D012964:Sodium; D000242:Cyclic AMP; D011493:Protein Kinase C; D000254:Sodium-Potassium-Exchanging ATPase; D000527:Alprostadil; D002118:Calcium