title: Interferon-gamma-mediated inhibition of serum response factor-dependent smooth muscle-specific gene expression.
abstract: IFNγ exerts multiple biological effects on effector cells by regulating many downstream genes, including smooth muscle-specific genes. However, the molecular mechanisms underlying IFNγ-induced inhibition of smooth muscle-specific gene expression remain unclear. In this study, we have shown that serum response factor (SRF), a common transcriptional factor important in cell proliferation, migration, and differentiation, is targeted by IFNγ in a STAT1-dependent manner. We show that the molecular mechanism by which IFNγ regulates SRF is via activation of the 2-5A-RNase L system, which triggers SRF mRNA decay and reduced SRF expression. As a result, decreased SRF expression reduces expression of SRF target genes such as smooth muscle α-actin and smooth muscle myosin heavy chain. Additionally, IFNγ reduced p300 and acetylated histone-3 binding in both smooth muscle α-actin and SRF promoters, epigenetically decreasing smooth muscle α-actin and SRF transcriptional activation. Our data reveal that SRF is a novel IFNγ-regulated gene and further elucidate the molecular pathway between IFNγ, IFNγ-regulated genes, and SRF and its target genes.
authors.affiliation: Department of Internal Medicine, Division of Digestive and Liver Diseases, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390, USA.
authors.forename: Zengdun
authors.initials: Z
authors.lastname: Shi
authors.forename: Don C
authors.initials: DC
authors.lastname: Rockey
mesh_terms: D000199:Actins / Q000235:genetics / Q000378:metabolism; D000818:Animals; D002478:Cells, Cultured; D004722:Endoribonucleases / Q000235:genetics / Q000378:metabolism; D005786:Gene Expression Regulation; D055166:Hepatic Stellate Cells / Q000166:cytology / Q000502:physiology; D006801:Humans; D007371:Interferon-gamma / Q000378:metabolism*; D051379:Mice; D008807:Mice, Inbred BALB C; D018345:Mice, Knockout; D009130:Muscle, Smooth / Q000502:physiology*; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D050794:STAT1 Transcription Factor / Q000235:genetics / Q000378:metabolism; D026362:Serum Response Factor / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology
chemical_list: D000199:Actins; D012333:RNA, Messenger; D050794:STAT1 Transcription Factor; D026362:Serum Response Factor; D007371:Interferon-gamma; D004722:Endoribonucleases; C031956:2-5A-dependent ribonuclease