title: Impact of high glucose and transforming growth factor-β on bioenergetic profiles in podocytes.
abstract: Diabetic nephropathy is the most common cause of chronic renal failure in industrialized countries. Depletion of podocytes plays an important role in the progression of diabetic glomerulopathy. Various factors in the diabetic milieu lead to serious podocyte stress driving the cells toward cell cycle arrest (p27(Kip1)), hypertrophy, detachment, and apoptosis. Mitochondria are responsible for oxidative phosphorylation and energy supply in podocytes. Recent studies indicated that mitochondrial dysfunction is a key factor in diabetic nephropathy. In the present study, we investigated metabolic profiles of podocytes under diabetic conditions. We examined oxygen consumption rates (OCRs) and oxidative phosphorylation complex activities in murine podocytes. Cells were exposed to high glucose for 48 hours, cultured for 10 passages under high-glucose conditions (30 mmol/L), or incubated with transforming growth factor-β (5 ng/mL) for 24 hours. After prolonged exposure to high glucose, podocytes showed a significantly increased OCR at baseline and also a higher OCR after addition of oligomycin, indicating significant changes in mitochondrial energy metabolism. Higher OCRs after inhibition of respiration by rotenone also indicated changes in nonmitochondrial respiration. Podocytes stimulated with a proapoptotic concentration of transforming growth factor-β displayed similar bioenergetic profiles, even with decreased citrate synthase activity. In all tested conditions, we found a higher cellular nicotinamide adenine dinucleotide content and changes in activities of respiratory chain complexes. In summary, we provide for the first time evidence that key factors of the diabetic milieu induce changes in glucose metabolism and mitochondrial function in podocytes.
authors.affiliation: Division of Nephrology, Department of Medicine, Hannover Medical School, Carl-Neuberg-Strasse 1, Hannover, Germany.
authors.forename: Nicole
authors.initials: N
authors.lastname: Stieger
authors.forename: Kirstin
authors.initials: K
authors.lastname: Worthmann
authors.forename: Beina
authors.initials: B
authors.lastname: Teng
authors.forename: Stefan
authors.initials: S
authors.lastname: Engeli
authors.forename: Anibh M
authors.initials: AM
authors.lastname: Das
authors.forename: Hermann
authors.initials: H
authors.lastname: Haller
authors.forename: Mario
authors.initials: M
authors.lastname: Schiffer
mesh_terms: D000818:Animals; D001786:Blood Glucose / Q000378:metabolism*; D002478:Cells, Cultured; D003921:Diabetes Mellitus, Experimental; D003928:Diabetic Nephropathies / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology; D005470:Fluorometry / Q000379:methods; D050533:Glomerular Basement Membrane / Q000187:drug effects / Q000378:metabolism; D060730:Glomerular Filtration Barrier / Q000187:drug effects; D051272:Glucose Transporter Type 1 / Q000378:metabolism; D006943:Hyperglycemia / Q000209:etiology / Q000378:metabolism*; D007150:Immunohistochemistry; D007202:Indicators and Reagents; D007678:Kidney Glomerulus / Q000187:drug effects / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D008928:Mitochondria / Q000201:enzymology / Q000378:metabolism*; D010078:Oxazines; D010084:Oxidation-Reduction; D010101:Oxygen Consumption; D010766:Phosphorylation; D050199:Podocytes / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism* / Q000473:pathology; D017382:Reactive Oxygen Species / Q000378:metabolism; D013384:Succinate Cytochrome c Oxidoreductase / Q000378:metabolism; D013385:Succinate Dehydrogenase / Q000378:metabolism; D016212:Transforming Growth Factor beta / Q000378:metabolism*; D014966:Xanthenes
chemical_list: D001786:Blood Glucose; D051272:Glucose Transporter Type 1; D007202:Indicators and Reagents; D010078:Oxazines; D017382:Reactive Oxygen Species; D016212:Transforming Growth Factor beta; D014966:Xanthenes; C005843:resazurin; D013384:Succinate Cytochrome c Oxidoreductase; D013385:Succinate Dehydrogenase