Stimulation of Na(+)-K(+)-ATPase by thyrotropin in cultured thyroid follicular cells.
Thyroid-stimulating hormone (TSH; thyrotropin) produces a pleiotropic response in the thyroid gland, accelerating nearly every aspect of metabolic turnover within the follicular epithelia. We examined the effects of TSH on expression of Na(+)-K(+)-ATPase in FRTL-5 cells, a cell line derived from rat thyroid. TSH (10 mU/ml) produced a nearly twofold increase in abundance of the mRNA encoding the catalytic alpha 1-subunit within 6 h of treatment. With the four mRNAs encoding the beta 1-subunit, TSH produced a striking increase in abundance, but this regulation was discoordinate, and some species increased more than others. Similar increases in mRNA abundance were elicited by activators of the adenosine 3',5'-cyclic monophosphate second messenger system. In contrast to the alpha 1- and beta 1-mRNAs, the abundance of the mRNA encoding the beta 2-subunit was unchanged with TSH after 6 h, indicating that the effects of thyrotropin were not universal or indiscriminate. Thyrotropin also caused a 76% increase in Na(+)-K(+)-ATPase activity and a 46% increase in pump-mediated transport after 48 h. These studies suggest that the changes in metabolic turnover initiated by TSH during hormone synthesis include upregulation of the N(+)-K+ pump.
Pressley
T A
TA
Department of Physiology and Cell Biology, University of Texas Medical School, Houston 77030, USA.
Higham
S C
SC
Joson
L A
LA
Mercer
D W
DW
D000818:Animals; D001693:Biological Transport, Active / Q000187:drug effects; D002478:Cells, Cultured; D007455:Iodine / Q000493:pharmacokinetics; D007477:Ions; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D011916:Rats, Inbred F344; D000254:Sodium-Potassium-Exchanging ATPase / Q000235:genetics / Q000378:metabolism*; D013961:Thyroid Gland / Q000166:cytology / Q000201:enzymology*; D013972:Thyrotropin / Q000494:pharmacology*
D007477:Ions; D012333:RNA, Messenger; D013972:Thyrotropin; D007455:Iodine; D000254:Sodium-Potassium-Exchanging ATPase