Serum and growth factor induction of Na(+)-K(+)-ATPase subunit mRNAs in Clone 9 cells: role of protein kinase C.
In a previous study, we found that addition of serum to confluent Clone 9 cells, a nontransformed rat liver cell line, increased the abundance of mRNA alpha 1 and mRNA beta 1 at 3 h by 2- and 2.7-fold, respectively [Bhutada et al. Am. J. Physiol. 258 (Cell Physiol. 27): C1044-C1050, 1990]. We now report that exposure of these cells to 160 nM 12-O-tetradecanoylphorbol 13-acetate (TPA) for 6 h increases mRNA alpha 1 and mRNA beta 1 by 1.7 +/- 0.2- and 2.1 +/- 0.3-fold, respectively. Incubation in the presence of 160 nM TPA for 24 h reduced high-affinity phorbol dibutyrate-binding sites [dissociation constant (Kd) = 5 nM; maximum binding (Bmax) = 1.2 pmol/mg protein] to undetectable levels. In such cells, exposure to 10% serum for 6 h still resulted in two- and fourfold increment in mRNA alpha 1 and mRNA beta 1 abundances, respectively, while further addition of TPA to these protein kinase C (PKC)-depleted cells resulted in no change in the subunit mRNA abundances. The increments in mRNA alpha 1 content in response to 10% serum and 160 nM TPA at 6 h were additive, whereas the increments in mRNA beta 1 were not. The following agents increased mRNA alpha 1 and mRNA beta 1 abundance in both control and PKC-depleted cells: epidermal growth factor, platelet-derived growth factor, basic fibroblast growth factor, insulin, dexamethasone, and hypothyroid calf serum. In contrast, N6,2'-O-dibutyryl-adenosine 3',5'-cyclic monophosphate and aldosterone had no effect.(ABSTRACT TRUNCATED AT 250 WORDS)
Bhutada
A
A
Department of Medicine, College of Physicians and Surgeons, Columbia University, New York, New York 10032.
Ismail-Beigi
F
F
D000818:Animals; D001790:Blood Physiological Phenomena; D002467:Cell Nucleus / Q000378:metabolism; D002999:Clone Cells; D003593:Cytoplasm / Q000378:metabolism; D006133:Growth Substances / Q000494:pharmacology*; D008099:Liver / Q000166:cytology / Q000201:enzymology*; D011493:Protein Kinase C / Q000502:physiology*; D012333:RNA, Messenger / Q000378:metabolism*; D000254:Sodium-Potassium-Exchanging ATPase / Q000235:genetics*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D006133:Growth Substances; D012333:RNA, Messenger; D011493:Protein Kinase C; D000254:Sodium-Potassium-Exchanging ATPase; D013755:Tetradecanoylphorbol Acetate