Immune Netw.  2014 Dec;14(6):321-327. 10.4110/in.2014.14.6.321.

SUMO Proteins are not Involved in TGF-beta1-induced, Smad3/4-mediated Germline alpha Transcription, but PIASy Suppresses it in CH12F3-2A B Cells

• Lee SH
• Kim PH
• Oh SM
• Park JH
• Yoo YC
• Lee J
• Park SR

• KMID: 2150822
• DOI: http://doi.org/10.4110/in.2014.14.6.321

Abstract

TGF-beta induces IgA class switching by B cells. We previously reported that Smad3 and Smad4, pivotal TGF-beta signal-transducing transcription factors, mediate germline (GL) alpha transcription induced by TGF-beta1, resulting in IgA switching by mouse B cells. Post-translational sumoylation of Smad3 and Smad4 regulates TGF-beta-induced transcriptional activation in certain cell types. In the present study, we investigated the effect of sumoylation on TGF-beta1-induced, Smad3/4-mediated GLalpha 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-beta1-induced, Smad3/4-mediated GLalpha promoter activity, expression of endogenous GLalpha transcripts, surface IgA expression, and IgA production. Next, we tested the effect of the E3 ligase PIASy on TGF-beta1-induced, Smad3/4-mediated GLalpha promoter activity. We found that PIASy overexpression suppresses the GLalpha promoter activity in cooperation with histone deacetylase 1. Taken together, these results suggest that SUMO itself does not affect regulation of GLalpha transcription and IgA switching induced by TGF-beta1/Smad3/4, while PIASy acts as a repressor.

Keyword

IgA; germline alpha transcripts; SUMO; PIASy; HDAC1

MeSH Terms

Animals
B-Lymphocytes*
Cell Line
Histone Deacetylase 1
Immunoglobulin A
Immunoglobulin Class Switching
Mice
Small Ubiquitin-Related Modifier Proteins*
SUMO-1 Protein*
Sumoylation
Transcription Factors
Transcriptional Activation
Transforming Growth Factor beta
Transforming Growth Factor beta1
Ubiquitin-Protein Ligases
Histone Deacetylase 1
Immunoglobulin A
SUMO-1 Protein
Small Ubiquitin-Related Modifier Proteins
Transcription Factors
Transforming Growth Factor beta
Transforming Growth Factor beta1
Ubiquitin-Protein Ligases