Nitric oxide inhibits the proliferation of murine microglial MG5 cells by a mechanism involving p21 but independent of p53 and cyclic guanosine monophosphate.
We investigated the effect of nitric oxide (NO) on the proliferation of microglial MG5 cells established from p53-deficient mice. Cells were treated with bacterial lipopolysaccharide and interferon-gamma, and expression of inducible NO synthase (iNOS) and p21/waf1, a cyclin-dependent kinase inhibitor protein which is a critical downstream effector of p53, was investigated by RNA blot and immunoblot analyses. iNOS mRNA was induced 2 h after treatment and increased with time up to 24 h. p21 mRNA was expressed at a low level in untreated cells and increased with a kinetics similar to that for iNOS mRNA. iNOS and p21 proteins were also induced. An NO donor SNAP induced p21 mRNA and protein. SNAP inhibited incorporation of [(3)H]thymidine in MG5 cells in a dose-dependent manner. 8-Bromo-cGMP neither induced p21 mRNA nor inhibited [(3)H]thymidine incorporation. These results suggest that NO inhibits the proliferation of MG5 cells by induction of p21, which occurs independent of p53 and cGMP.
Kawahara
K
K
Department of Biofunctional Chemistry, Faculty of Pharmaceutical Sciences, Kumamoto University, 5-1 Ohe-honmachi, Kumamoto 862-0973, Japan.
Gotoh
T
T
Oyadomari
S
S
Kuniyasu
A
A
Kohsaka
S
S
Mori
M
M
Nakayama
H
H
D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology; D002455:Cell Division / Q000502:physiology; D002478:Cells, Cultured; D006152:Cyclic GMP / Q000031:analogs & derivatives* / Q000378:metabolism* / Q000494:pharmacology; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins / Q000235:genetics / Q000378:metabolism*; D015870:Gene Expression / Q000187:drug effects / Q000502:physiology; D007371:Interferon-gamma / Q000494:pharmacology; D008070:Lipopolysaccharides / Q000494:pharmacology; D051379:Mice; D008817:Mice, Mutant Strains; D017628:Microglia / Q000166:cytology*; D009569:Nitric Oxide / Q000378:metabolism*; D020030:Nitric Oxide Donors / Q000494:pharmacology; D019001:Nitric Oxide Synthase / Q000235:genetics; D052247:Nitric Oxide Synthase Type II; D010396:Penicillamine / Q000031:analogs & derivatives* / Q000494:pharmacology; D012333:RNA, Messenger / Q000032:analysis; D016159:Tumor Suppressor Protein p53 / Q000235:genetics* / Q000378:metabolism
D000970:Antineoplastic Agents; C493957:Cdkn1a protein, mouse; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D008070:Lipopolysaccharides; D020030:Nitric Oxide Donors; D012333:RNA, Messenger; C110881:S-nitro-N-acetylpenicillamine; D016159:Tumor Suppressor Protein p53; C016276:8-bromocyclic GMP; D009569:Nitric Oxide; D007371:Interferon-gamma; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse; D010396:Penicillamine; D006152:Cyclic GMP