1,25(OH)₂D₃ ALLEVIATES OLEIC ACID-INDUCED LIPID ACCUMULATION IN HEPG2 CELLS BY REGULATING CALCIUM HOMEOSTASIS AND INHIBITING ENDOPLASMIC RETICULUM STRESS

YU Yuan-tong; JI Shu-qi; ZHANG Jia-nan; WANG Xiao-ting; HAN Hao

Acta Nutrimenta Sinica ›› 2026, Vol. 48 ›› Issue (2) : 155-163.

YU Yuan-tong, JI Shu-qi, ZHANG Jia-nan, WANG Xiao-ting, HAN Hao

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Abstract

Objective To investigate the effects of 1,25(OH)₂D₃ on oleic acid (OA)-induced lipid accumulation in hepatocytes and elucidate the underlying mechanism by focusing on the regulation of calcium ion balance and the alleviation of endoplasmic reticulum stress (ERS). Methods HepG2 cells were divided into three groups: a control group cultured in normal medium, an OA group treated with 1.5 mmol/L OA, and an OA+VD group treated with 1.5 mmol/L OA and 0.1 μmol/L 1,25(OH)₂D₃. All treatments were maintained for 24 hours. Lipid accumulation was evaluated using Oil Red O staining. Cellular triglyceride (TG) levels were measured using a commercial assay kit. Intracellular calcium ion levels were measured with Fluo-4 fluorescent probe. To evaluate the expression and cellular localization of GRP78, immunofluorescence staining was performed. The protein expression levels of protein kinase r-like endoplasmic reticulum kinase (PERK), phosphorylated protein kinase r-like endoplasmic reticulum kinase(p-PERK), eukaryotic translation initiation factor 2 subunit Alpha (eIF2α),phosphorylated eukaryotic translation initiation factor 2α subunit (p-eIF2α), sterol regulatory element-binding protein 1c (SREBP-1c), acetyl-CoA carboxylase (ACC), and fatty acid synthase (FAS) were measured by Western blot. Results Compared with the control group, the OA group exhibited a significant increase in lipid droplet accumulation and a marked elevation in TG content. These pathological changes were significantly ameliorated in the OA+VD group. Mechanistic investigations revealed that the OA+VD group had a notably restored intracellular calcium ion balance and a significantly downregulated expression of GRP78. Meanwhile, the ERS-related PERK/eIF2α signaling pathway and its downstream fatty acid synthesis pathway involving SREBP-1c, ACC and FAS were significantly suppressed. Conclusion 1,25(OH)₂D₃ can alleviate OA-induced fat accumulation in HepG2 cells. The underlying mechanism is associated with the restoration of intracellular calcium homeostasis and inhibition of ERS.

Key words

1,25(OH)₂D₃ / HepG2 cells / oleic acid / lipid accumulation / endoplasmic reticulum stress

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YU Yuan-tong, JI Shu-qi, ZHANG Jia-nan, WANG Xiao-ting, HAN Hao. 1,25(OH)₂D₃ ALLEVIATES OLEIC ACID-INDUCED LIPID ACCUMULATION IN HEPG2 CELLS BY REGULATING CALCIUM HOMEOSTASIS AND INHIBITING ENDOPLASMIC RETICULUM STRESS[J]. Acta Nutrimenta Sinica. 2026, 48(2): 155-163

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