Transcriptional and post-transcriptional mechanisms regulate human
renin gene expression in calu-6 cells.
Lang, Julie A., Li-Hua Ying, Brian J. Morris & Curt D. Sigmund.
Departments of Internal Medicine and Physiology & Biophysics,
University of Iowa College of Medicine, Iowa City, Iowa 52242 and
Molecular Biology & Hypertension Laboratory, Department of
Physiology, University of Sydney, Sydney, NSW 2006 Australia
APStracts 3:0022F, 1996.
We have recently identified a human pulmonary carcinoma cell line
(Calu-6) which expresses human renin (hREN) mRNA endogenously and use
it herein as a model to examine the regulation of the hREN gene.
Transfection analysis of a deletion series (-2750 to -149) of hREN
promoter-luciferase fusion constructs revealed the presence of
multiple weak regulatory elements within the first 1301 bp of the 5'
flanking region, and a classical silencer element within the first
intron (intron-A) of the gene. The 5' flanking regulatory domain
consisted of three closely linked elements, two negative and one
positive, each contributing a cell-specific three-fold modulation of
transcriptional activity. Treating Calu-6 cells with forskolin caused
a 100-fold increase in steady state endogenous hREN mRNA but no
increase in hREN promoter activity in transient transfections or in
nuclear runoff transcription assays. Nevertheless, de novo
transcription and translation was necessary for cAMP-mediated
induction. Our results suggest that multiple regulatory elements
regulate basal transcriptional activity of the hREN gene and the
increase in hREN mRNA by cAMP may be mediated by post-transcriptional
mechanisms.
Received 6 September 1995; accepted in final form 19 January
1996.
APS Manuscript Number F294-5.
Article publication pending Am. J. Physiol. (Renal Fluid Electrolyte
Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 8 February 96