Ubiquitin C-terminal hydrolase-L5 is required for high glucose-induced transforming growth factor-β receptor I expression and hypertrophy in mesangial cells

• Published in: Archives of biochemistry and biophysics 2013-07, Vol.535 (2), p.177-186
• Main Authors: Ko, Yu-Min, Chang, Chun-Ying, Chiou, Shean-Jaw, Hsu, Fu-Jie, Huang, Jau-Shyang, Yang, Yu-Lin, Guh, Jinn-Yuh, Chuang, Lea-Yea
• Format: Article
• Language: English
• Subjects: Animals; Carboxypeptidases - metabolism; Cell Line; Cell Size; Cyclic AMP Response Element-Binding Protein - metabolism; Cyclin-Dependent Kinase Inhibitor p21 - genetics; Cyclin-Dependent Kinase Inhibitor p21 - metabolism; Diabetes Mellitus, Experimental - metabolism; diabetic nephropathy; fibronectins; Fibronectins - metabolism; glucose; Glucose - metabolism; growth retardation; High glucose; hypertrophy; Kidney Glomerulus - metabolism; Kidney Tubules - metabolism; Male; Mesangial cells; Mesangial Cells - cytology; Mesangial Cells - metabolism; messenger RNA; Mice; pathogenesis; phosphatidylinositol 3-kinase; Phosphatidylinositol 3-Kinases - metabolism; protein synthesis; Protein-Serine-Threonine Kinases - metabolism; Rats; Rats, Sprague-Dawley; Receptors, Transforming Growth Factor beta - metabolism; RNA, Messenger - metabolism; small interfering RNA; TGF-β; transforming growth factor beta; ubiquitin; Ubiquitin Thiolesterase; Ubiquitination; UCHL5
• ISSN: 0003-9861; 1096-0384
• DOI: 10.1016/j.abb.2013.03.003

•High glucose induces TGF-βR1 via PI3K-UCHL5 in mesangial cells.•High glucose decreases TGF-βR1 protein ubiquitination.•High glucose induces p21WAF1 and fibronectin protein expression and cell hypertrophy via UCHL5. Transforming growth factor-β (TGF-β) is pivotal in the pathogenesis of diabetic nephropathy. Type 1 TGF-β receptor (TGF-βR1) is degraded by Smad7-dependent ubiquitination–proteasomal pathway, which is deubiquitinated by ubiquitin C-terminal hydrolase-L5 (UCHL5). Therefore, we studied the role of UCHL5 in high glucose (27.8mM)-induced TGF-βR1 protein expression in mouse mesangial (MES13) cells. UCHL5 short hairpin RNA (shRNA) was used to knock down UCHL5 while LY294002 and the dominant-negative p85 were used to inhibit phosphatidylinositol-3-kinase (PI3K). We found that high glucose increased phospho-Akt, TGF-βR1 mRNA and protein expression. High glucose also increased UCHL5 protein expression, which was attenuated by LY294002, the dominant-negative p85 and the dominant-negative CREB. High glucose-induced TGF-βR1 protein expression and TGF-βR1 protein deubiquitination were attenuated by UCHL5 shRNA. Additionally, high glucose-induced p21WAF1, fibronectin protein expression and cell hypertrophy were attenuated by UCHL5 shRNA. However, high glucose-induced TGF-βR1 mRNA, p27kip1 protein expression and growth inhibition were not affected by UCHL5 shRNA. Finally, glomerular UCHL5 and TGF-βR1 protein expression were increased in streptozotocin-diabetic rats at 8weeks. We conclude that PI3K-dependent UCHL5 is required for high glucose-induced TGF-βR1 protein expression in mesangial cells. UCHL5 is also required for high glucose-induced TGF-βR1 protein deubiquitination, p21WAF1 and fibronectin protein expression and cell hypertrophy.