title: SUMO Proteins are not Involved in TGF-β1-induced, Smad3/4-mediated Germline α Transcription, but PIASy Suppresses it in CH12F3-2A B Cells.
abstract: TGF-β induces IgA class switching by B cells. We previously reported that Smad3 and Smad4, pivotal TGF-β signal-transducing transcription factors, mediate germline (GL) α transcription induced by TGF-β1, resulting in IgA switching by mouse B cells. Post-translational sumoylation of Smad3 and Smad4 regulates TGF-β-induced transcriptional activation in certain cell types. In the present study, we investigated the effect of sumoylation on TGF-β1-induced, Smad3/4-mediated GLα transcription and IgA switching by mouse B cell line, CH12F3-2A. Overexpression of small ubiquitin-like modifier (SUMO)-1, SUMO-2 or SUMO-3 did not affect TGF-β1-induced, Smad3/4-mediated GLα promoter activity, expression of endogenous GLα transcripts, surface IgA expression, and IgA production. Next, we tested the effect of the E3 ligase PIASy on TGF-β1-induced, Smad3/4-mediated GLα promoter activity. We found that PIASy overexpression suppresses the GLα promoter activity in cooperation with histone deacetylase 1. Taken together, these results suggest that SUMO itself does not affect regulation of GLα transcription and IgA switching induced by TGF-β1/Smad3/4, while PIASy acts as a repressor.
authors.affiliation: Department of Microbiology, College of Medicine, Konyang University, Daejeon 302-718, Korea.
authors.forename: Sang-Hoon
authors.initials: SH
authors.lastname: Lee
authors.affiliation: Department of Molecular Bioscience, School of Biomedical Science, Kangwon National University, Chuncheon 200-701, Korea.
authors.forename: Pyeung-Hyeun
authors.initials: PH
authors.lastname: Kim
authors.affiliation: Department of Biochemistry, College of Medicine, Konyang University, Daejeon 302-718, Korea.
authors.forename: Sang-Muk
authors.initials: SM
authors.lastname: Oh
authors.affiliation: Department of Biochemistry, College of Medicine, Konyang University, Daejeon 302-718, Korea.
authors.forename: Jung-Hwan
authors.initials: JH
authors.lastname: Park
authors.affiliation: Department of Microbiology, College of Medicine, Konyang University, Daejeon 302-718, Korea.
authors.forename: Yung-Choon
authors.initials: YC
authors.lastname: Yoo
authors.affiliation: Department of Microbiology, College of Medicine, Konyang University, Daejeon 302-718, Korea.
authors.forename: Junglim
authors.initials: J
authors.lastname: Lee
authors.affiliation: Department of Microbiology, College of Medicine, Konyang University, Daejeon 302-718, Korea.
authors.forename: Seok-Rae
authors.initials: SR
authors.lastname: Park
keywords: HDAC1; IgA; PIASy; SUMO; germline α transcripts