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Sp1 and Smad3 are required for high glucose‐induced p21 WAF1 gene transcription in LLC‐PK 1 cells
Author(s) -
Chuang TsaiDer,
Guh JinnYuh,
Chiou SheanJaw,
Chen HungChun,
Hung WenChun,
Chuang LeaYea
Publication year - 2007
Publication title -
journal of cellular biochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.028
H-Index - 165
eISSN - 1097-4644
pISSN - 0730-2312
DOI - 10.1002/jcb.21346
Subject(s) - transfection , microbiology and biotechnology , muscle hypertrophy , transcription (linguistics) , gene , biology , gene expression , transcription factor , chemistry , cell growth , endocrinology , biochemistry , linguistics , philosophy
The cyclin‐dependent kinase inhibitor p21 WAF1 is required for diabetic glomerular hypertrophy. High glucose‐induced hypertrophy in proximal tubule cells is dependent on transforming growth factor‐β (TGF‐β). Many of the TGF‐β‐induced effects are dependent on Smad2/3. Thus, the molecular mechanisms of high glucose‐induced p21 WAF1 and hypertrophy were studied in high glucose‐cultured proximal tubule‐like LLC‐PK 1 cells. We found that high glucose (30 mM) induced hypertrophy at 72 h. High glucose also increased the expression of p21 WAF1 protein and p21 WAF1 mRNA transcription and abundance at 48 h. The DNA element in the 5′ regulatory region of p21 WAF1 gene essential for high glucose‐induced p21 WAF1 gene transcription was identified as Sp1 by a series of the 5′ regulatory region of p21 WAF1 gene deletion mutants. Moreover, high glucose activated Smad2/3 while increasing the Sp1 DNA‐binding activity. High glucose also increased the Sp1‐dependent transcriptional activity of p21 WAF1 gene. High glucose‐induced hypertrophy was attenuated by p21 WAF1 short interfering RNA and Smad3 dominant‐negative plasmid transfection. We concluded that high glucose induced hypertrophy via Sp1‐Smad2/3‐dependent activation of p21 WAF1 gene transcription in LLC‐PK 1 cells. J. Cell. Biochem. 102: 1190–1201, 2007. © 2007 Wiley‐Liss, Inc.