The expression and significance of mTORC1 in diabetic retinopathy

Meixia An,Yekai Zhou,Yi Liu,Wenjing Meng,Yarong Zheng,Yanli Liu,Mengxuan Xie

doi:10.1186/s12886-020-01553-3

Abstract

BackgroundTo investigate the expression and significance of mechanistic target of rapamycin complex 1(mTORC1) in diabetic retinopathy (DR), and to find new targets and new methods for the treatment of DR.MethodsA DR rat model was prepared by general feeding combined with intraperitoneal injection of 10% streptozotocin (60 mg/kg). The rats were randomly divided into a control group (NDM group) and a diabetes group (DM group). Three months later, the degrees of retinopathy was determined using hematoxylin and eosin staining, and the levels of p-S6, VEGF, and PEDF proteins were detected by immunohistochemistry and western blotting. Human retinal capillary endothelial cells (HRCECs) were cultured in high glucose (HG) conditions, then treated with rapamycin or transfected with siTSC1.The protein levels of p-S6 were assessed by western blotting. The 5-ethynyl-2′-deoxyuridine assay was used to detect cell proliferation, and the Transwell assay was used to detect cell migration.ResultsA DM rat model was successfully developed. The expressions of p-S6 and VEGF proteins were significantly increased in the DM group (p < 0.05), and the expression of PEDF protein was significantly decreased compared with the NDM group (p < 0.05). In vitro, the p-S6 protein, as well as cell proliferation and migration, in HG induced HRCECs were increased (p < 0.05) compared with the control (normal glucose) group (p < 0.05). After transfection with siTSC1 to activate mTORC1, the expression of p-S6, as well as cell proliferation and migration, were increased. In contrast, rapamycin decreased p-S6 expression, as well as proliferation and migration, in HG induced HRCECs compared to the control group (p < 0.05).ConclusionmTORC1 plays an important role in DR. After activation, mTORC1 induced expression of the p-S6 protein, regulated the expressions of VEGF and PEDF proteins, and changed the proliferation and migration of endothelial cells. The mTORC1 can therefore be used as a new target,as well as in the treatment of DR.

Highlights

To investigate the expression and significance of mechanistic target of rapamycin complex 1(mTORC1) in diabetic retinopathy (DR), and to find new targets and new methods for the treatment of DR
We found that vascular endothelial growth factor (VEGF) was highly expressed in the retinas of diabetic rats, while pigment epithelium-derived factor (PEDF) was significantly decreased in the retinas of diabetic rats, when compared with nondiabetic rats (Fig. 2b, c)
The mammalian target of rapamycin (mTOR) is a serine/threonine protein kinase,which is highly conserved in structure and function, belonging to a phosphatidylinositol 3-kinase (PI3K)-related family member [21]. mTOR mainly exists in the form of two complexes in vivo: Mechanistic target of rapamycin complex 1 (mTORC1), which regulates cell proliferation and metabolic reactions and mTORC2

Summary

Introduction

To investigate the expression and significance of mechanistic target of rapamycin complex 1(mTORC1) in diabetic retinopathy (DR), and to find new targets and new methods for the treatment of DR. The mammalian target of rapamycin (mTOR) is a highly conserved serine/threonine protein kinase in structure and function, involving mTORC1, and is a central signaling molecule that integrates various pathways inside and outside cells, regulates cell growth and metabolism, and provides an important molecular link between nutritional signals and metabolic processes necessary for cell growth. It mainly promotes cell growth, proliferation and differentiation by activating key anabolic processes. The roles of mTORC1 in aberrant endothelial cell proliferation and migration, and the crucial events in DR progression, as well as its underlying mechanisms, are not known

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