AJP - Cell Physiology, Vol 262, Issue 4 C854-C861, Copyright © 1992 by American Physiological Society
Transcriptional regulation of the endothelin-1 gene by TNF-alpha
P. A. Marsden and B. M. Brenner
Department of Medicine, St. Michael's Hospital, University of Toronto, Ontario, Canada.
Cytokines, such as tumor necrosis factor-alpha (TNF-alpha), induce profound
alterations in endothelial cell phenotype and are implicated in the organ
dysfunction that characterizes septic shock. We explored whether TNF-alpha
modulates cellular expression of endothelin-1 (ET-1). ET-1 is a potent
vasoconstrictor peptide released by endothelial, vascular smooth muscle,
and mesangial cells that could function as a paracrine/autocrine regulator
of vascular tone and proliferation. We found that TNF-alpha induced release
of ET-1 from bovine aortic endothelial cells (BAEC) in a time- and
concentration-dependent manner. Rates of ET-1 release were maximal over 1-8
h and declined to, or below, baseline values after 16 h. When measured at 8
h, TNF-alpha augmented ET-1 release over the range 0.1-250 ng/ml
(threshold, 0.1 ng/ml; 50% effective dose, 1.6 +/- 1.2 ng/ml; maximal
effect, 100 ng/ml). The increase in secretion was accompanied by a
corresponding increase in the transcriptional rate of the ET-1 gene
resulting in augmented preproendothelin-1 mRNA transcript levels.
TNF-alpha-stimulated increases in ET-1 gene transcription were not
dependent on new protein synthesis. Actinomycin D chase experiments
suggested that enhanced stability of preproendothelin-1 mRNA could not
account for the increase in ET-1 transcript levels. TNF-alpha increased
ET-1 release and preproendothelin-1 mRNA content in bovine renal artery and
bovine glomerular capillary endothelial cells, demonstrating that the
TNF-alpha effect was evident in endothelial cells derived from a variety of
sources. Furthermore, augmented ET-1 expression in response to TNF-alpha
was evident in bovine glomerular mesangial cells.(ABSTRACT TRUNCATED AT 250
WORDS)
