title: Protein inhibitor of activated STAT, PIASy regulates α-smooth muscle actin expression by interacting with E12 in mesangial cells.
abstract: Phenotypic transformation of mesangial cells (MCs) is implicated in the development of glomerular disease; however, the mechanisms underlying their altered genetic program is still unclear. α-smooth muscle actin (α-SMA) is known to be a crucial marker for phenotypic transformation of MCs. Recently, E-boxes and the class I basic helix-loop-helix proteins, such as E12 have been shown to regulateα-SMA expression. Therefore, we tried to identify a novel E12 binding protein in MCs and to examine its role in glomerulonephritis. We found that PIASy, one of the protein inhibitors of activated STAT family protein, interacted with E12 by yeast two-hybrid screens and coimmunopreciptation assays. Overexpression of E12 significantly enhanced theα-SMA promoter activity, and the increase was blocked by co-transfection of PIASy, but not by a PIASy RING mutant. In vivo sumoylation assays revealed that PIASy was a SUMO E3 ligase for E12. Furthermore, transforming growth factor-β (TGF-β) treatment induced expression of both PIASy and E12, consistent with α-SMA expression. Moreover, reduced expression of PIASy protein by siRNA specific for PIASy resulted in increased TGF-β-mediated α-SMA expression. In vivo, PIASy and E12 were dramatically upregulated along with α-SMA and TGF-β in the proliferative phase of Thy1 glomerulonephritis. Furthermore, an association between PIASy and E12 proteins was observed at day 6 by IP-western blotting, but not at day 0. These results suggest that TGF-β up-regulates PIASy expression in MCs to down-regulateα-SMA gene transcription by the interaction with E12.
authors: Department of Nephrology, Kyoto University Graduate School of Medicine, Kyoto, Japan.
authors: Kazuo
authors: K
authors: Torikoshi
authors: Hideharu
authors: H
authors: Abe
authors: Takeshi
authors: T
authors: Matsubara
authors: Takahiro
authors: T
authors: Hirano
authors: Takayuki
authors: T
authors: Ohshima
authors: Taichi
authors: T
authors: Murakami
authors: Makoto
authors: M
authors: Araki
authors: Akira
authors: A
authors: Mima
authors: Noriyuki
authors: N
authors: Iehara
authors: Atsushi
authors: A
authors: Fukatsu
authors: Toru
authors: T
authors: Kita
authors: Hidenori
authors: H
authors: Arai
authors: Toshio
authors: T
authors: Doi
mesh_terms: D000199:Actins / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D015153:Blotting, Western; D019556:COS Cells; D002460:Cell Line; D049109:Cell Proliferation; D006801:Humans; D007150:Immunohistochemistry; D047468:Immunoprecipitation; D008297:Male; D050527:Mesangial Cells / Q000378:metabolism*; D011485:Protein Binding; D050828:Protein Inhibitors of Activated STAT; D034622:RNA Interference; D051381:Rats; D011921:Rats, Inbred WKY; D020133:Reverse Transcriptase Polymerase Chain Reaction; D058127:Transcription Factor 3 / Q000235:genetics / Q000378:metabolism*; D020798:Two-Hybrid System Techniques
chemical_list: D000199:Actins; D050828:Protein Inhibitors of Activated STAT; D058127:Transcription Factor 3