Abstract
Interleukin-1beta (IL-1beta) induces the inducible nitric oxide synthase (iNOS), resulting in the release of nitric oxide (NO) from glomerular mesangial cells. In this study, we demonstrated that disruption of F-actin formation by sequestration of G-actin with the toxin latrunculin B (LatB) dramatically potentiated IL-1beta-induced iNOS protein expression in a dose-dependent manner. LatB by itself had little or no effect on iNOS expression. Staining of F-actin with nitrobenzoxadiazole (NBD)-phallacidin demonstrated that LatB significantly impaired F-actin stress fiber formation. Jasplakinolide (Jasp), which binds to and stabilizes F-actin, suppressed iNOS expression enhanced by LatB. These data strongly suggest that actin cytoskeletal dynamics regulates IL-1beta-induced iNOS expression. We demonstrated that LatB decreases serum response factor (SRF) activity as determined by reporter gene assays, whereas Jasp increases SRF activity. The negative correlation between SRF activity and iNOS expression suggests a negative regulatory role for SRF in iNOS expression. Overexpression of a dominant negative mutant of SRF increases the IL-1beta-induced iNOS expression, providing direct evidence that SRF inhibits iNOS expression.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Actins / drug effects
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Actins / physiology*
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Actins / ultrastructure
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Animals
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Bridged Bicyclo Compounds, Heterocyclic / pharmacology*
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Cells, Cultured
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Cytoskeleton / drug effects
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Cytoskeleton / physiology*
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Cytoskeleton / ultrastructure
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DNA-Binding Proteins / metabolism
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Depsipeptides*
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Gene Expression Regulation, Enzymologic / drug effects
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Gene Expression Regulation, Enzymologic / physiology*
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Genes, Reporter
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Genes, fos
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Glomerular Mesangium / cytology
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Glomerular Mesangium / physiology*
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Glomerular Mesangium / ultrastructure
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Interleukin-1 / pharmacology*
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Kinetics
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Luciferases / analysis
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Luciferases / genetics
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Male
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Marine Toxins / pharmacology
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Nitric Oxide Synthase / analysis
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Nitric Oxide Synthase / genetics*
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Nitric Oxide Synthase Type II
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Nuclear Proteins / metabolism
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Peptides, Cyclic / pharmacology
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Rats
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Rats, Sprague-Dawley
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Serum Response Factor
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Thiazoles / pharmacology*
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Thiazolidines
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Transcription Factors / metabolism
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Transfection
Substances
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Actins
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Bridged Bicyclo Compounds, Heterocyclic
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DNA-Binding Proteins
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Depsipeptides
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Interleukin-1
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Marine Toxins
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Nuclear Proteins
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Peptides, Cyclic
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Serum Response Factor
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Thiazoles
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Thiazolidines
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Transcription Factors
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jasplakinolide
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Luciferases
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Nitric Oxide Synthase
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Nitric Oxide Synthase Type II
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Nos2 protein, rat
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latrunculin B