Mechanism of Paeonol Mediates the Regulation of VDAC1 by lncRNA MALAT1 to Improve Endoplasmic Reticulum-mitochondrial Dysfunction in Chondrocytes of Osteoarthritis

OBJECTIVE To investigate the mechanism by which paeonol(PAE) regulates voltage-dependent anion channel 1(VDAC1) to ameliorate endoplasmic reticulum-mitochondrial dysfunction in osteoarthritic chondrocytes via the long non-coding RNA transfer-associated lung adenocarcinoma transcript 1(lncRNA MALAT1), using both in vivo and in vitro experiments.

METHODS In vivo experiments, C57BL/6 mice were randomly divided into blank group(n=10) and modeling group(n=40). The model group underwent OA modeling via modified Hulth surgery, followed by secondary grouping into model group, lncRNA MALAT1 overexpression group, model+PAE group, and lncRNA MALAT1 overexpression+PAE group. After relevant interventions, samples were collected from each group. The morphological changes of articular cartilage in each group of mice were observed by staining with HE, safranin O-fast green, Masson and toluidine blue. RT-PCR was used to detect the gene expression levels of lncRNA MALAT1, VDAC1, C/EBP-homologous protein(CHOP), cytochrome-c(Cyt-C) and matrix metallopeptidase-13(MMP-13) in cartilage tissue. Western blotting analysis was performed to detect the expression levels of VDAC1, protein kinase R-like endoplasmic reticulum kinase(PERK), CHOP, Bcl-2-associated X Protein(Bax), Cyt-C and MMP-13 proteins in articular cartilage tissue. In vitro experiments, chondrocytes were induced with interleukin-1β(IL-1β) to establish an arthritis cell model that conforms to the characteristics of OA. lncRNA MALAT1 knockdown(sh-MALAT1) chondrocytes were constructed via lentiviral plasmid transfection. Fluorescence in situ hybridization(FISH), RT-PCR, and Western blotting further validated the molecular mechanism by which PAE ameliorates endoplasmic reticulum-mitochondrial dysfunction induced by IL-1β in chondrocytes.

RESULTS In vivo experiments demonstrated, PAE could improve the morphological structure of joint cartilage in OA mice. Compared with the model group, the model+paeoniflorin group showed reduced expression of relevant genes and proteins(P<0.05), while overexpression of lncRNA MALAT1 diminished the therapeutic effect of PAE. In vitro results, FISH showed that PAE can weaken the fluorescence intensity of lncRNA MALAT1 in OA chondrocytes under IL-1β intervention. In IL-1β-treated OA chondrocytes, lncRNA MALAT1, VDAC1, CHOP, Cyt-C and MMP-13 genes were highly expressed; PAE intervention reversed this trend. Compared with the IL-1β group, the IL-1β+sh-MALAT1 group showed reduced expression of these genes(P<0.05). Compared with the IL-1β+sh-MALAT1 group, the IL-1β+sh-MALAT1+PAE group showed reduced expression of the relevant genes(P<0.05). Western blotting analysis revealed that PAE improved the expression of relevant proteins in IL-1β-induced sh-MALAT1 chondrocytes(P<0.05).

CONCLUSION These findings demonstrate that PAE mediates lncRNA MALAT1 regulation of VDAC1 to improve endoplasmic reticulum-mitochondrial dysfunction in OA chondrocytes.