Regulation of inducible nitric oxide synthase expression by viral A238L-mediated inhibition of p65/RelA acetylation and p300 transactivation.
Uncontrolled generation of nitric oxide (NO) by inducible nitric-oxide synthase (iNOS) can cause damage to host cells and inflammation, two undesirable events for virus spreading. African swine fever virus (ASFV) infection regulates iNOS-induced gene expression through the synthesis of the A238L virus protein. We here explored the role of A238L, an NF-kappaB and NFAT inhibitor, in the regulation of iNOS transcription in macrophages. NO production and iNOS mRNA and protein levels as well as iNOS promoter activity after lipopolysaccharide (LPS)-gamma interferon (IFN-gamma) treatment were down-regulated both during ASFV infection and in Raw 264.7 cells stably expressing the viral protein. Overexpression of p300, but not of a histone acetyltransferase (HAT) defective mutant, reverted the A238L-mediated inhibition of both basal and LPS-IFN-gamma-induced iNOS promoter activity. Following stimulation with LPS-IFN-gamma, p65 and p300 interaction was abolished in Raw-A238L cells. Expression of A238L also inhibited p65/relA and p300 binding to the distal NF-kappaB sequence of the iNOS promoter together with p65 acetylation. Finally, A238L abrogated p300 transactivation mediated by a GAL4-p300 construction. These results provide evidence for an unique viral mechanism involved in transcriptional regulation of iNOS gene expression.
Granja
Aitor G
AG
Centro de Biología Molecular Severo Ochoa, Universidad Autónoma de Madrid, Madrid 28049, Spain.
Sabina
Prado
P
Salas
María L
ML
Fresno
Manuel
M
Revilla
Yolanda
Y
D000107:Acetylation; D000358:African Swine Fever Virus / Q000235:genetics / Q000472:pathogenicity / Q000502:physiology*; D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D002478:Cells, Cultured; D004279:DNA, Viral / Q000235:genetics; D015536:Down-Regulation; D015971:Gene Expression Regulation, Enzymologic; D008264:Macrophages / Q000201:enzymology / Q000821:virology; D051379:Mice; D016328:NF-kappa B / Q000378:metabolism; D009569:Nitric Oxide / Q000096:biosynthesis; D052247:Nitric Oxide Synthase Type II / Q000235:genetics*; D011401:Promoter Regions, Genetic; D013552:Swine; D051996:Transcription Factor RelA / Q000378:metabolism; D014158:Transcription, Genetic; D014764:Viral Proteins / Q000235:genetics / Q000502:physiology*; D050880:p300-CBP Transcription Factors / Q000378:metabolism
C113585:A238L protein, African swine fever virus; D004279:DNA, Viral; D016328:NF-kappa B; C498144:Rela protein, mouse; D051996:Transcription Factor RelA; D014764:Viral Proteins; D009569:Nitric Oxide; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse; D050880:p300-CBP Transcription Factors