Involvement of over-production of IP 3R-Grp75-VDAC1-MCU calcium axis molecules accompanied with mTORC1 hyper-activation in Adriamycin induced nephropathy rat / 中华实用儿科临床杂志

ABSTRACT

Objective:To investigate the expression of inositol 1, 4, 5-triphate receptor (IP 3R)-glucose-regulated protein 75 (Grp75)-voltage dependent anion channel 1 (VDAC1)-mitochondrial Calcium uniporter (MCU) Calcium axis molecules in proteinuria and to explore its upstream regulator. Methods:Sixteen Sprague Dawley rats were divided into control group (6 rats) and Adriamycin (ADR) group (10 rats). Nephropathy rat model was established by single injection of ADR through tail vein.The glomerular expression of IP 3R, Grp75, VDAC1, MCU and the activation marker of mammalian target of Rapamycin complex 1 (mTORC1) were analyzed by immunohistochemical staining.In cultured mouse podocyte, ADR was used to induce podocyte injury, and the Everolimus of different concentrations was applied for intervention.The expression of the Calcium axis molecules and apoptosis marker was analyzed. Results:Compared with control group, the glomerular expression of IP 3R (0.02±0 vs.0, P<0.001), Grp75 (0.04±0 vs.0, P<0.001), VDAC1 (0.04±0 vs.0.01±0, P<0.001), and MCU (0.05±0.01 vs.0.01±0, P<0.001) were significantly increased in ADR-induced nephropathy rats, and the activation marker of mTORC1 (0.57±0.01 vs.0.18±0, P<0.001) was increased as well.In cultured mouse podocytes, compared with control group, the expression of Grp75 (1.89±1.17 vs.0.16±0.08, P=0.001), VDAC1 (1.59±0.34 vs.0.20±0.07, P=0.006), and MCU (1.56±0.38 vs.0.46±0.35, P=0.014) were obviously increased in ADR induced podocytes, and the activation marker of mTORC1 (2.12±0.08 vs.0.39±0.09, P<0.001) was also increased.Compared with the ADR induced podocytes, the expression of Grp75 (0.26±0.20 vs.1.89±1.17, P=0.001), VDAC1 (0.40±0.26 vs.1.59±0.34, P=0.014) and MCU (0.60±0.32 vs.1.56±0.38, P=0.029) in podocytes treated with ADR and 1.0 nmol/L Everolimus were remarkably decreased, accompanied with the decrease of mitochondrial calcium [(2 664.00±140.57) U vs.(3 025.16±180.92) U, P=0.023] and apoptosis marker cleaved Caspase-3 (0.55±0.28 vs.1.48±0.45, P=0.011). Conclusions:The over-production of IP 3R-Grp75-VDAC1-MCU Calcium axis molecules accompanied with the hyper-activation of mTORC1 was involved in ADR induced nephropathy rats.mTORC1 inhibitor decreased the expression of Calcium axis molecules in mouse podocytes, which might involve in the mechanism of mTORC1 inhibitor′s effects on podocyte.