Proteomics analysis reveals diabetic kidney as a ketogenic organ in type 2 diabetes.
Diabetic nephropathy (DN) is the leading cause of end-stage renal disease. To date, the molecular mechanisms of DN remain largely unclear. The present study aimed to identify and characterize novel proteins involved in the development of DN by a proteomic approach. Proteomic analysis revealed that 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) synthase 2 (HMGCS2), the key enzyme in ketogenesis, was increased fourfold in the kidneys of type 2 diabetic db/db mice. Consistently, the activity of HMGCS2 in kidneys and 24-h urinary excretion of the ketone body β-hydroxybutyrate (β-HB) were significantly increased in db/db mice. Immunohistochemistry, immunofluorescence, and real-time PCR studies further demonstrated that HMGCS2 was highly expressed in renal glomeruli of db/db mice, with weak expression in the kidneys of control mice. Because filtered ketone bodies are mainly reabsorbed in the proximal tubules, we used RPTC cells, a rat proximal tubule cell line, to examine the effect of the increased level of ketone bodies. Treating cultured RPTC cells with 1 mM β-HB significantly induced transforming growth factor-β1 expression, with a marked increase in collagen I expression. β-HB treatment also resulted in a marked increase in vimentin protein expression and a significant reduction in E-cadherin protein levels, suggesting an enhanced epithelial-to-mesenchymal transition in RPTCs. Collectively, these findings demonstrate that diabetic kidneys exhibit excess ketogenic activity resulting from increased HMGCS2 expression. Enhanced ketone body production in the diabetic kidney may represent a novel mechanism involved in the pathogenesis of DN.
Zhang
Dongjuan
D
Dept. of Physiology and Pathophysiology, Peking University Health Science Ctr., Haidian District, Beijing, China.
Yang
Hang
H
Kong
Xiaomu
X
Wang
Kang
K
Mao
Xuan
X
Yan
Xianzhong
X
Wang
Yuan
Y
Liu
Siqi
S
Zhang
Xiaoyan
X
Li
Jing
J
Chen
Lihong
L
Wu
Jing
J
Wei
Mingfen
M
Yang
Jichun
J
Guan
Youfei
Y
D020155:3-Hydroxybutyric Acid / Q000378:metabolism; D000818:Animals; D015153:Blotting, Western; D002478:Cells, Cultured; D024042:Collagen Type I / Q000096:biosynthesis; D003924:Diabetes Mellitus, Type 2 / Q000235:genetics* / Q000378:metabolism*; D003928:Diabetic Nephropathies / Q000235:genetics* / Q000378:metabolism*; D004848:Epithelium / Q000378:metabolism; D005455:Fluorescent Antibody Technique; D006904:Hydroxymethylglutaryl-CoA Synthase / Q000378:metabolism; D007150:Immunohistochemistry; D066298:In Vitro Techniques; D007657:Ketone Bodies / Q000096:biosynthesis*; D007668:Kidney / Q000378:metabolism*; D007678:Kidney Glomerulus / Q000378:metabolism; D007687:Kidney Tubules, Proximal / Q000166:cytology / Q000378:metabolism; D008648:Mesoderm / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D040901:Proteomics; D012313:RNA / Q000096:biosynthesis / Q000235:genetics; D051381:Rats; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D016212:Transforming Growth Factor beta / Q000096:biosynthesis
D024042:Collagen Type I; D007657:Ketone Bodies; D016212:Transforming Growth Factor beta; D012313:RNA; D006904:Hydroxymethylglutaryl-CoA Synthase; D020155:3-Hydroxybutyric Acid