Transforming growth factor-beta 1, but not dexamethasone, down-regulates nitric-oxide synthase mRNA after its induction by interleukin-1 beta in rat smooth muscle cells.
Nitric oxide (NO), which accounts for the biologic properties of endothelium-derived relaxing factor, is synthesized from L-arginine by nitric-oxide synthase (NOS). Two classes of NOS have been identified: a constitutive, calcium-dependent isozyme (cNOS) and an inducible, calcium-independent isozyme (iNOS). NO is generated after the induction of iNOS by cytokines such as interleukin-1 beta (IL-1 beta) and tumor necrosis factor-alpha. As a potent vasodilator, NO may have an important role in the severe hypotension of septic shock. We investigated whether dexamethasone and transforming growth factor-beta 1 (TGF-beta 1) suppress iNOS mRNA after its induction by IL-1 beta. We found that IL-1 beta induced iNOS mRNA in rat aortic smooth muscle cells (RASMC) in a dose- and time-dependent fashion. IL-1 beta promoted a dramatic and prolonged induction of RASMC iNOS mRNA that peaked at 48 h. Dexamethasone prevented this induction of iNOS mRNA only when given before the addition of IL-1 beta. In contrast, TGF-beta 1 inhibited the induction of iNOS mRNA and NO production in RASMC both before and after the addition of IL-1 beta. After 24 h of IL-1 beta stimulation, TGF-beta 1 down-regulated the iNOS mRNA that had been induced during this initial time period. In nuclear run-on experiments, we found that the down-regulation of iNOS mRNA by TGF-beta 1 in RASMC occurred at the transcriptional level. Our observation that TGF-beta 1 mediates inhibition of RASMC iNOS mRNA after its induction by cytokines may be an important insight into the treatment of septic shock.
Perrella
M A
MA
Cardiovascular Biology Laboratory, Harvard School of Public Health, Boston, Massachusetts 02115.
Yoshizumi
M
M
Fen
Z
Z
Tsai
J C
JC
Hsieh
C M
CM
Kourembanas
S
S
Lee
M E
ME
D000594:Amino Acid Oxidoreductases / Q000096:biosynthesis*; D000818:Animals; D001011:Aorta / Q000187:drug effects / Q000201:enzymology*; D001483:Base Sequence; D002478:Cells, Cultured; D003513:Cycloheximide / Q000494:pharmacology; D017931:DNA Primers; D003609:Dactinomycin / Q000494:pharmacology; D003907:Dexamethasone / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004790:Enzyme Induction / Q000187:drug effects; D015870:Gene Expression / Q000187:drug effects*; D007375:Interleukin-1 / Q000096:biosynthesis*; D007700:Kinetics; D008297:Male; D008969:Molecular Sequence Data; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000201:enzymology*; D019001:Nitric Oxide Synthase; D009573:Nitrites / Q000378:metabolism; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000096:biosynthesis*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013997:Time Factors; D014158:Transcription, Genetic / Q000187:drug effects; D016212:Transforming Growth Factor beta / Q000494:pharmacology*
D017931:DNA Primers; D007375:Interleukin-1; D009573:Nitrites; D012333:RNA, Messenger; D016212:Transforming Growth Factor beta; D003609:Dactinomycin; D003907:Dexamethasone; D003513:Cycloheximide; D019001:Nitric Oxide Synthase; D000594:Amino Acid Oxidoreductases