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Sumoylation of Sp1 is involved in its degradation
Author(s) -
Wang YiTing,
Chang WenChang,
Hung JanJong
Publication year - 2007
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.21.5.a627-c
Subject(s) - sumo protein , sp1 transcription factor , ubiquitin , biology , rnf4 , transcription (linguistics) , microbiology and biotechnology , lysine , transcription factor , gene , chemistry , promoter , gene expression , biochemistry , zinc finger , amino acid , linguistics , philosophy
Sp1 is a ubiquitously expressed transcription factor that plays important role in the regulation of mamy GC‐rich genes encoding for housekeeping proteins. The transcriptional activity of Sp1 is mainly determined by three elements: transcriptional activity, DNA binding ability and its protein stability. Previous studies, including our laboratory, have shown that the posttranslational modification are implicated in the regulation of Sp1 activity and modulates the expression of Sp1‐target genes. The posttranslational modifications of Sp1 include phosphorylation, glycosylation, acetylation, ubiquitination and sumoylation. Our study has shown that the sumoylation site of Sp1 is located in the lysine 9 of Sp1 (778 amino acids). Moreover its target genes such as p21 and 12(S)‐Lox were negatively regulated upon the sumoylation of Sp1. However, the underlying mechanism is still unclear. Our preliminary data showed that the protein level of sumoylation‐deficient Sp1 (K9R) was higher compared to Sp1 wild type. However, the RNA and ubiquitination level of sumoylation‐deficient Sp1 did not change. Therefore, we infer that sumoylation of Sp1 is involved with its degradation mechanism. The protein level of Sp1 decreased and negatively regulated target genes through the sumoylation of Sp1. At present, we will focus in elucidating the mechanism how the sumoylation‐deficient Sp1 could increase its protein stability without affecting its ubiquitination level. Our preliminary results show that sumoylation of Sp1 increases the interaction with proteasome subunit Rpt6 and induces its degradation.