Apoptosis of tubular epithelial cells in glycogen nephrosis during diabetes.
The important problem of the fate of glycogen-accumulating clear cells in glycogen nephrosis is still unsettled. In this study, we examine whether apoptosis plays a relevant role in the development of diabetic glycogen nephrosis and explore the involvement of the Fas/Fas-L system and the activation of the caspase cascade. Diabetes was induced in rats by streptozotocin injection. Glycogen-accumulating clear cells were identified in renal tissues of hyperglycemic rats. They were found to be concentrated in the thick ascending limbs and distal tubules. Large cellular glycogen accumulations were confirmed by biochemical assays and enzyme-gold cytochemistry. Clear cells displayed apoptotic features such as Annexin V binding, nuclear TUNEL (terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling), and the simultaneous occurrence of Fas, Annexin V, and TUNEL positivity. Western blot analysis demonstrated enhanced expression of Fas receptor/ligand and the activation of the caspase cascade in these cells because cleaved forms of the caspase-3, -8, and -9 were detected. Furthermore, active caspase-3 was located in nuclei by immunoelectron microscopy. Our results indicate that epithelial cells in thick ascending limbs and distal tubules that develop glycogen nephrosis in response to hyperglycemia undergo Fas/Fas-L mediated cell death. Thus, apoptosis could be playing a significant role in renal epithelial cell deletion during diabetes.
Bamri-Ezzine
Saoussen
S
Department of Pathology and Cell Biology, Université de Montréal, Montréal, Québec, Canada.
Ao
Zhu Jun
ZJ
Londoño
Irene
I
Gingras
Diane
D
Bendayan
Moïse
M
D000818:Animals; D017304:Annexin A5 / Q000378:metabolism; D017209:Apoptosis; D020169:Caspases / Q000378:metabolism; D002452:Cell Count; D002467:Cell Nucleus / Q000378:metabolism / Q000648:ultrastructure; D003921:Diabetes Mellitus, Experimental / Q000150:complications / Q000378:metabolism / Q000473:pathology*; D004848:Epithelium / Q000378:metabolism / Q000473:pathology; D053222:Fas Ligand Protein; D006003:Glycogen / Q000378:metabolism; D038362:Glycogen Synthase Kinase 3 / Q000378:metabolism; D000071679:Glycogen Synthase Kinase 3 beta; D007150:Immunohistochemistry; D007686:Kidney Tubules, Distal / Q000378:metabolism / Q000473:pathology*; D008297:Male; D008562:Membrane Glycoproteins / Q000378:metabolism; D009401:Nephrosis / Q000150:complications / Q000378:metabolism / Q000473:pathology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D019014:fas Receptor / Q000378:metabolism
D017304:Annexin A5; D053222:Fas Ligand Protein; C505662:Faslg protein, rat; D008562:Membrane Glycoproteins; D019014:fas Receptor; D006003:Glycogen; D000071679:Glycogen Synthase Kinase 3 beta; D038362:Glycogen Synthase Kinase 3; D020169:Caspases