Role of endoplasmic reticulum stress in apoptosis of differentiated mouse podocytes induced by high glucose
Authors: Qingjuan Liu
Hang Li
Yongmei Hao
Feng Gao
Huijun Duan
Wei Liu
Yanping Cao
Journal: International Journal of Molecular Medicine (2014)
Discipline: CLINICAL MEDICINE
Keywords: Podocytes; apoptosis; endoplasmic reticulum stress; diabetic nephropathy; high glucose
Affiliations: Department of Pathology, Hebei Medical University, Shijiazhuang, Hebei 050017, P.R. China., Department of Endocrinology, The Second Hospital of Hebei Medical University, Shijiazhuang, Hebei 050000, P.R. China., Department of Histology and Embryology, Hebei Medical University, Shijiazhuang, Hebei 05001, P.R. China., Department of Pathology, The Third Hospital, Hebei Medical University, Shijiazhuang, Hebei 050051, P.R. China.

Abstract:  Podocytes are terminally differentiated epithelial cells lacking the ability to proliferate. The loss of podocytes is a hallmark of progressive kidney diseases, including diabetic nephropathy (DN). Endoplasmic reticulum stress (ERS)-induced apoptosis is involved in a number of pathological conditions, including DN. The aim of the present study was to investigate whether a high glucose environment induces the apoptosis of podocytes through ERS. Differentiated mouse podocytes were divided into three groups: the normal glucose group (NG, 1 g/l D-glucose), the high glucose group (HG, 4.5 g/l D-glucose) and the mannitol group (M, 1 g/l D-glucose plus 24.4 mM mannitol). The cells were harvested following stimulation with the indicated treatments for 12, 24, 48 and 72 h. Podocyte apoptosis was determined using TUNEL assay and flow cytometry (propidium iodide staining). Glucose-regulated protein 78 (GRP78), CCAAT/enhancer-binding protein (C/EBP) homologous protein (CHOP/GADD153) and caspase-12 expression was analyzed by RT-PCR, western blot analysis and immunocytochemistry. The apoptotic rate increased significantly in the HG group compared with the NG and M groups at 48 and 72 h (all P&lt;0.01). GRP78 expression, an indicator of ERS, was increased from 12 h, indicating that ERS was activated. Subsequently, two ER-associated death (ERAD) pathways, the CHOP/GADD153- and caspase‑12-dependent pathways, were detected. CHOP/GADD153 expression reached its peak at 48 h, and caspase-12 expression gradually increased with time. Spearman's correlation analysis revealed that caspase-12 and CHOP/GADD153 positively correlated with the apoptotic rate (r=0.915, P&lt;0.01 and r=0.639, P&lt;0.01). Our results demonstrated that hyperglycemia (high glucose) induced apoptosis partly through ERS in the differentiated mouse podocytes, which possibly contributes to the pathogenesis of DN. 

Retracted: No

PubPeer comments:
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