title: Analysis of induction mechanisms of an insulin-inducible transcription factor SHARP-2 gene by (-)-epigallocatechin-3-gallate.
abstract: The rat enhancer of split- and hairy-related protein-2 (SHARP-2) is an insulin-inducible transcription factor. In this study, we examined the mechanism(s) involved in the regulation of the rat SHARP-2 gene expression by (-)-epigallocatechin-3-gallate (EGCG). The induction of SHARP-2 mRNA by EGCG was repressed by pretreatments with inhibitors for either phosphoinositide 3-kinase (PI3K) or RNA polymerase II. Then, we examined a biological relationship between EGCG and transcription factor NF-κB interfering with the insulin action. The protein levels of the NF-κB were rapidly decreased by an EGCG treatment. Finally, the mechanism(s) of transcriptional activation of the rat SHARP-2 gene by both NF-κB and EGCG was analyzed. While overexpression of the NF-κB p65 protein decreased the promoter activity of the SHARP-2 gene, EGCG did not affect it. Thus, we conclude that EGCG induces the expression of the rat SHARP-2 gene via both the PI3K pathway and degradation of the NF-κB p65 protein.
authors.affiliation: Department of Health and Nutritional Science, Faculty of Human Health Science,  Matsumoto University , 2095-1 Niimura, Matsumoto, Nagano 390-1295, Japan.
authors.forename: Ayumi
authors.initials: A
authors.lastname: Haneishi
authors.forename: Katsuhiro
authors.initials: K
authors.lastname: Takagi
authors.forename: Kosuke
authors.initials: K
authors.lastname: Asano
authors.forename: Soichiro
authors.initials: S
authors.lastname: Nakamura
authors.forename: Kazuya
authors.initials: K
authors.lastname: Yamada
mesh_terms: D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics* / Q000378:metabolism; D002392:Catechin / Q000031:analogs & derivatives* / Q000494:pharmacology; D018398:Homeodomain Proteins / Q000235:genetics* / Q000378:metabolism; D007328:Insulin / Q000378:metabolism*; D016328:NF-kappa B / Q000235:genetics / Q000378:metabolism; D051381:Rats; D051996:Transcription Factor RelA / Q000235:genetics / Q000378:metabolism; D015854:Up-Regulation / Q000187:drug effects*
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D002392:Catechin; D018398:Homeodomain Proteins; D007328:Insulin; D016328:NF-kappa B; D051996:Transcription Factor RelA; C491538:Bhlhe40 protein, rat; C045651:epigallocatechin gallate