Exploring the Mechanism of Rongjin Niantong Formula in Improving Endoplasmic Reticulum Stress of Chondrocytes Based on lncRNA Mirg and PERK/BIP Pathway

OBJECTIVE  To explore the mechanism of Rongjin Niantong Formula in improving endoplasmic reticulum stress of chondrocytes based on lncRNA Mirg and protein kinase R-like endoplasmic reticulum kinase(PERK)/binding immunoglobulin protein(BIP) pathway.

METHODS  The model of endoplasmic reticulum stress was established by inducing mice articular chondrocytes with thapsigarin. LncRNA Mirg was silenced by lentivirus transfection. Chondrocytese were divided into 4 groups(sh-NC group, sh-Mirg group, TG+sh-NC group and TG+sh-Mirg group), Rongjin Niantong Formula was applied to endoplasmic reticulum stress model chondrocytes, which were divided into three groups(blank group, model group, treatment group). Real-time qPCR and Western blotting were used to detect the expression of lncRNA Mirg, the gene level and protein content of PERK/BIP pathway, such as PERK, BIP, activating transcription factor 4(ATF4) and C/EBP-homologous protein(CHOP) were detected, and confocal laser microscope was used to detect the intracellular Ca²⁺ concentration.

RESULTS  This study successfully constructed lncRNA Mirg-deficient chondrocytes and induced endoplasmic reticulum stress model by thapsigarin. LncRNA Mirg deletion alleviated endoplasmic reticulum stress and reduced gene and protein expression of BIP, PERK, ATF4 and CHOP, key indicators of PERK/BIP pathway(P<0.05 or P<0.01). Intervention of Rongjin Niantong Formula reduced the gene and protein content of lncRNA Mirg and key indicators of PERK/BIP pathway(P<0.01) in chondrocytes, and regulated cellular Ca²⁺ flow.

CONCLUSION Rongjin Niantong Formula down-regulates the expression of lncRNA Mirg in chondrocytes, regulates the PERK/BIP pathway, restores the homeostasis of intracellular Ca²⁺, relieves the endoplasmic reticulum stress induces by toxic carotene, and delayes the degeneration of chondrocytes in osteoarthritis.