Nf-mb and gtp cyclohydrolase regulate cytokine-induced nitric oxide
production by cardiac myocytes.
Oddis, Carmine V., Mitchell S. Finkel.
Departments of Pathology, Surgery, Medicine and Pharmacology,
University of Pittsburgh, PA 15213
APStracts 3:0082H, 1996.
We have previously reported that interleukin-1[beta] (IL-1) alone
stimulated nitric oxide (NO) production by neonatal rat cardiac
myocytes in culture (CM). The present studies were undertaken to
explore the signal transduction pathways involved in IL-1 induced NO
production by CM. Translocation from the cytosol to the nucleus of
nuclear factor kappa B (NF-MB) and activation of GTP cyclohydrolase
(rate-limiting enzyme in tetrahydrobiopterin (BH4) synthesis) have
been implicated in IL-1 signaling. Accordingly, the effects of the
NF-MB inhibitor, pyrolidine dithiocarbamate (PDTC) and the GTP
cyclohydrolase inhibitor, 2,4-diamino-hydroxy-pyrimidine (DAHP), on
IL-1 induced NO production by CM were studied. Both PDTC and DAHP
inhibited IL-1 induced NO2- production by CM (6.7+/-0.6vs.0.9+/-0.3
and 0.3+/-0.1nmol/1.25x105cells/ 48hrs.,respectively;p<.01;n=12,
for each). Immunohistochemical staining revealed that PDTC blocked
IL-1 stimulated nuclear translocation of NF-MB. The membrane
permeable analogue of the NO synthase co-factor, BH4, methyl-BH4,
(mBH4), only partially reversed DAHP inhibition of NO2- formation
(6.7+/-0.6vs.2.4+/-0.3nmol/1.25x105cells/48hrs.;p<.01;n=12).
Semi-quantitative RT-PCR revealed no inducible NO synthase (iNOS)
mRNA production in cells treated with IL-1 + PDTC. CM treated with
IL-1 + DAHP did express iNOS mRNA. We report for the first time that
nuclear translocation of NF-MB is essential for Il-1 induced iNOS
mRNA expression and GTP-cyclohydrolase activity is required in
addition to BH4 for optimal NO production by CM.
Received 1 December 1995; accepted in final form 14 February
1996.
APS Manuscript Number H1119-5.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 13 March 96