Inducible Nitric Oxide Synthase iNOS

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Inducible Nitric Oxide Synthase (iNOS)
SIGMA-ALDRICH
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Inducible Nitric Oxide Synthase
(iNOS) Macrophages are important for early immune
responses to invading microorganisms, and the
production of nitric oxide (NO) is central to
this function. NO is generated by inducible
nitric oxide synthase (iNOS, macNOS, Type II NOS)
following exposure to certain cytokines, such as
interferon-? (IFN-?). The IFN-? receptor signals
through the Janus kinase (JAK) family and signal
transducers and activators of transcription
(STAT) proteins. Receptor occupation and
dimerization induces the phosphorylation of
associated STATs. Activated STATs dimerize and
translocate to the nucleus where they increase
expression of the transcription factor, IRF-1,
that, in turn, binds to specific DNA elements in
the iNOS gene promoter region to increase iNOS
gene expression. iNOS is a soluble enzyme that,
unlike eNOS and nNOS, does not require elevated
intracellular Ca2 levels for activation. Referenc
es Massa, P.T., et al., Increased inducible
activation of NF-?B and responsive genes in
astrocytes deficient in the protein tyrosine
phosphatase SHP-1. J. Interferon Cytokine Res.,
18, 499-507 (1998). Fehr, T., et al., Crucial
role of interferon consensus sequence binding
protein, but neither of interferon regulatory
factor 1 nor of nitric oxide synthesis for,
protection against murine listeriosis. J. Exp.
Med., 185, 921-931 (1997).