title: Involvement of a Stat3 binding site in inflammation-induced enteric apelin expression.
abstract: Apelin is the endogenous ligand for the APJ receptor; both are expressed in the gastrointestinal tract. Experimental colitis in rodents and inflammatory bowel disease in humans are associated with increased intestinal apelin production. Our aim was to use LPS and proinflammatory cytokine-treated (IL-6 and IFN-gamma) rodents or enteric cells to identify signaling mechanisms underlying inflammation-induced enteric apelin expression. LPS, IL-6, or IFN-gamma treatment of rodents increased enteric apelin expression. Pharmacological blockade of Jak/Stat signaling or IL-6 antibody administration inhibited elevations in enteric apelin expression. Transient transfection experiments showed that LPS, IL-6, or IFN-gamma increased apelin expression by stimulation of apelin promoter activity, and blockade of Jak/Stat signaling abolished elevations in apelin promoter activity. A chromatin immunoprecipitation assay showed that IL-6 induced binding of phospho-Stat3 to a putative Stat3 site in the apelin promoter; mutation of this site abrogated the LPS-induced elevation in apelin promoter activity. Together, our findings indicate that binding of phospho-Stat3 to the apelin promoter is the final step underlying proinflammatory cytokine-induced enteric apelin expression during intestinal inflammation.
authors.affiliation: Dept. of Surgery, Univ. of Texas Medical Branch, Galveston, TX 77555, USA.
authors.forename: Song
authors.initials: S
authors.lastname: Han
authors.forename: Guiyun
authors.initials: G
authors.lastname: Wang
authors.forename: Xiang
authors.initials: X
authors.lastname: Qi
authors.forename: Ella W
authors.initials: EW
authors.lastname: Englander
authors.forename: George H
authors.initials: GH
authors.lastname: Greeley
mesh_terms: D054392:Adipokines; D000818:Animals; D000073861:Apelin; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D002478:Cells, Cultured; D005753:Gastric Mucosa / Q000378:metabolism; D005786:Gene Expression Regulation; D007082:Ileum / Q000378:metabolism*; D007249:Inflammation / Q000139:chemically induced / Q000378:metabolism*; D036341:Intercellular Signaling Peptides and Proteins; D007371:Interferon-gamma / Q000378:metabolism; D015850:Interleukin-6 / Q000378:metabolism; D053612:Janus Kinases / Q000378:metabolism; D008070:Lipopolysaccharides; D051379:Mice; D008810:Mice, Inbred C57BL; D008819:Mice, Nude; D011485:Protein Binding; D051381:Rats; D017207:Rats, Sprague-Dawley; D050796:STAT3 Transcription Factor / Q000235:genetics / Q000378:metabolism*
chemical_list: D054392:Adipokines; D000073861:Apelin; C402826:Apln protein, mouse; C498579:Apln protein, rat; D002352:Carrier Proteins; D036341:Intercellular Signaling Peptides and Proteins; D015850:Interleukin-6; D008070:Lipopolysaccharides; D050796:STAT3 Transcription Factor; C494087:Stat3 protein, mouse; C494088:Stat3 protein, rat; D007371:Interferon-gamma; D053612:Janus Kinases