Different distribution and expression of mammalian target of rapamycin complex in the kidney of diabetic nephropathy mice / 解剖学报

ABSTRACT

Objective To investigate the different distribution and expression of mammalian target of rapamycin complex (mTORC) in the kidney of diabetic nephropathy (DN) mice.Methods Fourteen eight-week-old male C57BL/6 mice were assigned to 2 groups the control group ( n=7 ) and the streptozotocin ( STZ )-induced DN group ( n=7 ) . Blood and urinary variables including glucose , albumin, creatinine and albumin/creatinine ratio were assessed 2 weeks after STZ injection.Hematoxylin-eosin staining was performed for renal pathological analyses .The distributions of mTOR , phosph-ser2448-mTOR(p-mTOR), mTORC1(Raptor), mTORC2(Rictor) and phosph-ser240/244-S6K1 (p-S6K1) were determined by immunofluorescence.The expression levels of mTOR, p-mTOR, mTORC1(Raptor), mTORC2(Rictor), S6K1 and p-S6K1 were detected by Western blotting .Results Two weeks after STZ injection , the diabetic mice developed albuminuria (P<0.01) and renal hypertrophy (P<0.05).The immunofluorescence positive staining for mTOR , Raptor, and Rictor was distributed in the epithelial cells of proximal tubules , glomerular mesangium and capillary loops as well as the medullary collecting ducts of the control mouse kidney .These positive signals increased in the DN mouse kidney ( P<0.05).However, pS6K1 was not detected in the inner medulla of control mouse and p-mTOR was not found in the glomeruli of both control and DN mice .Conclusion mTORC is widely expessed in the mouse kidney and participates in the development of DN , whereas the 2448 serine phosphorylation of mTOR may be not implicated in the hyperglycemia mediated glomerular injury .