TY - JOUR
T1 - Bacterial lipopolysaccharide plus interferon-γ elicit a very fast inhibition of a Ca2+-dependent nitric-oxide synthase activity in human astrocytoma cells
AU - Colasanti, Marco
AU - Cavalieri, Elisabetta
AU - Persichini, Tiziana
AU - Mollace, Vincenzo
AU - Mariotto, Sofia
AU - Suzuki, Hisanori
AU - Lauro, Giuliana M.
PY - 1997
Y1 - 1997
N2 - Previous results indicate that induction of inducible nitric-oxide synthase (iNOS) expression may be kept suppressed by the endogenous NO level as produced by a constitutive NOS (cNOS) enzyme. In cell types possessing both cNOS and iNOS, this may represent an evident paradox. Here, we report that lipopolysaccharide and interferon-γ, which are able to strongly induce iNOS in astrocytoma cells, can rapidly inhibit the NO production generated by the constitutive NOS isoform, thus obtaining the best conditions for iNOS induction and resolving the apparent paradox. In fact, a 30-rain treatment of T67 cells with the combination of lipopolysaccharide plus interferon-γ (MIX) strongly inhibits the cNOS activity, as determined by measuring [3H]citrulline production. In addition, the effect of MIX is also observed by measuring nitrite, the stable breakdown product of NO: a 30-min pretreatment of T67 cells with MIX is able to reduce significantly the N- methyl-D-aspartate-induced nitrite production. Finally, using reverse transcriptase-polymerase chain reaction, we have observed that a 30-min treatment of T67 cells with MIX does not affect expression of mRNA coding for the neuronal NOS-I isoform. These results suggest the novel concept of a possible role of a cNOS isoform in astrocytes as a control function on iNOS induction.
AB - Previous results indicate that induction of inducible nitric-oxide synthase (iNOS) expression may be kept suppressed by the endogenous NO level as produced by a constitutive NOS (cNOS) enzyme. In cell types possessing both cNOS and iNOS, this may represent an evident paradox. Here, we report that lipopolysaccharide and interferon-γ, which are able to strongly induce iNOS in astrocytoma cells, can rapidly inhibit the NO production generated by the constitutive NOS isoform, thus obtaining the best conditions for iNOS induction and resolving the apparent paradox. In fact, a 30-rain treatment of T67 cells with the combination of lipopolysaccharide plus interferon-γ (MIX) strongly inhibits the cNOS activity, as determined by measuring [3H]citrulline production. In addition, the effect of MIX is also observed by measuring nitrite, the stable breakdown product of NO: a 30-min pretreatment of T67 cells with MIX is able to reduce significantly the N- methyl-D-aspartate-induced nitrite production. Finally, using reverse transcriptase-polymerase chain reaction, we have observed that a 30-min treatment of T67 cells with MIX does not affect expression of mRNA coding for the neuronal NOS-I isoform. These results suggest the novel concept of a possible role of a cNOS isoform in astrocytes as a control function on iNOS induction.
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U2 - 10.1074/jbc.272.12.7582
DO - 10.1074/jbc.272.12.7582
M3 - Article
C2 - 9065411
AN - SCOPUS:0030903881
VL - 272
SP - 7582
EP - 7585
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
SN - 0021-9258
IS - 12
ER -