Viability of primary cultured podocytes is associated with extracellular high glucose-dependent autophagy downregulation

Authors:
Audzeyenka I, Rogacka D, Piwkowska A, Angielski S, Jankowski M.
In:
Source: Mol Cell Biochem
Publication Date: (2017)
Issue: 430(1-2): 11-19
Research Area:
Gene Expression
Cells used in publication:
Podocyte, mouse
Species: mouse
Tissue Origin: kidney
Platform:
4D-Nucleofector® Y-Unit
Experiment
Plasmid transfection for visualizing autophagosomes in podocytes: rat podocytes seeded on type I collagen-coated 24-well plates (Greiner Bio-One, Austria) at 70–80% confluency were transfected with an Amaxa AD1 Primary Cell 4D-Nucleofector-Y Kit (Lonza, Switzerland) and ptfLC3 plasmid (16 µg per well) using the FB-166 program on the 4D-Nucleofector System (Lonza). Immediately after nucleofection, cells were transferred into 1 ml of pre-warmed RPMI 1640 medium. SiRNA transfection: Podocytes were cultured in type I collagen-coated culture flasks in RPMI 1640 with 10% FBS and then transfected with siRNA Transfection Reagent (Santa Cruz Biotechnology) following the manufacturer’s instructions. Nonspecific (scrambled) siRNA and Atg5 siRNA were diluted in Transfection Medium to a final concentration of 50 nM.
Abstract
Structural and functional impairment of podocytes plays an important role in the development of diabetic nephropathy, a chronic complication of diabetes mellitus and leading cause of renal failure requiring renal replacement therapy. Autophagy plays a crucial role in podocyte viability and function, and its activity is modulated by a variety of pathophysiological factors found in diabetic milieu. Here we show that downregulation of autophagy is critical for podocyte survival in hyperglycemic environment. Moreover, long-term exposure to high glucose leads to inhibition of autophagy as well as to the development of insulin resistance in podocytes. Furthermore, impairment of autophagy is involved in alteration of insulin-dependent glucose uptake in podocytes, suggesting a relationship between these two processes. Taken together, our findings suggest that downregulation of podocyte autophagy, observed after long-term exposure to high glucose, results from their suppressed sensitivity to insulin, and may therefore lead to diminished podocyte cell viability as well as their reduced number in glomerulus.