Mechanisms of suppression of macrophage nitric oxide release by transforming growth factor beta.

  • Y Vodovotz
    Beatrice and Samuel A. Seaver Laboratory, Department of Medicine, Cornell University Medical College, New York, New York 10021.
  • C Bogdan
    Beatrice and Samuel A. Seaver Laboratory, Department of Medicine, Cornell University Medical College, New York, New York 10021.
  • J Paik
    Beatrice and Samuel A. Seaver Laboratory, Department of Medicine, Cornell University Medical College, New York, New York 10021.
  • Q W Xie
    Beatrice and Samuel A. Seaver Laboratory, Department of Medicine, Cornell University Medical College, New York, New York 10021.
  • C Nathan
    Beatrice and Samuel A. Seaver Laboratory, Department of Medicine, Cornell University Medical College, New York, New York 10021.

抄録

<jats:p>Activated mouse peritoneal macrophages produce nitric oxide (NO) via a nitric oxide synthase that is inducible by interferon gamma (IFN-gamma): iNOS. We have studied the mechanisms by which transforming growth factor beta 1 (TGF-beta) suppresses IFN-gamma-stimulated NO production. TGF-beta treatment reduced iNOS specific activity and iNOS protein in both cytosolic and particulate fractions as assessed by Western blot with monospecific anti-iNOS immunoglobulin G. TGF-beta reduced iNOS mRNA without affecting the transcription of iNOS by decreasing iNOS mRNA stability. Even after iNOS was already expressed, TGF-beta reduced the amount of iNOS protein. This was due to reduction of iNOS mRNA translation and increased degradation of iNOS protein. The potency of TGF-beta as a deactivator of NO production (50% inhibitory concentration, 5.6 +/- 2 pM) may reflect its ability to suppress iNOS expression by three distinct mechanisms: decreased stability and translation of iNOS mRNA, and increased degradation of iNOS protein. This is the first evidence that iNOS is subject to other than transcriptional regulation.</jats:p>

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