Stimulation of na+-k+-atpase by thyrotropin in cultured thyroid follicular
cells.
Pressley, Thomas A., Sandra C. Higham, Lisa A. Joson, and David W. Mercer.
Departments of Physiology and Cell Biology and of Surgery, University of
Texas Medical School, 6431 Fannin, Houston, Texas 77030, 713 792-5914, FAX:
713 794-1349
APStracts 2:0029C, 1995.
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 two-fold increase in abundance of the mRNA
encoding the catalytic 1-subunit within 6 h of treatment. With the four mRNAs
encoding the 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 cyclic AMP second messenger system. In contrast to the 1- and 1-mRNAs,
the abundance of the mRNA encoding the 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 up-regulation of the Na+-K+-pump.
Received 6 July 1994; accepted in final form 16 November 1994
APS Manuscript Number C0385-4.
Article publication pending Am. J. Physiol. (Cell Physiology).
ISSN 1080-4757 Copyright 1994 The American Physiological Society.
Published in APStracts on 27 February 1995.