[Mechanism of ring finger protein 11 regulating Akt signaling pathway to promote osteogenic differentiation of bone marrow mesenchymal stem cells].

Abstract

To investigate the role and regulatory mechanism of ring finger protein 11 (RNF11) on Akt signaling pathway in the process of osteogenesis of bone marrow mesenchymal stem cells (BMSCs) to provide ideas for further clarifying its osteogenesis mechanism and its use in clinical treatment in the future. BMSCs were isolated and cultured from fresh bone marrow of healthy donors and subcultured. The 4th generation cells were used in experiments after identification by flow cytometry, and osteogenic, chondrogenic, and adipogenic induction. BMSCs were cultured in osteogenic differentiation medium for 0-14 days. The degree of osteogenic differentiation was detected by Alizarin red staining and alkaline phosphatase (ALP) staining, and the protein expression of RNF11 was detected by Western blot. The 4th generation BMSCs were divided into blank control group (group A), empty lentivirus (Lv-NC) group (group B), and knockdown RNF11 (Lv-ShRNF11) group (group C). Osteogenesis was induced and cultured for 0-14 days. The expression of RNF11 protein was detected by Western blot, the degree of osteogenic differentiation was detected by Alizarin red staining and ALP staining, and the relative mRNA expressions of Runx2, osteocalcin (OCN), and osteopontin (OPN) were detected by real-time fluorescence quantitative PCR (qRT-PCR). The protein relative expressions of Akt, Smad1/5/8, and β-catenin signaling pathway were detected by Western blot, expressed as the ratio before and after phosphorylation. In order to study the effect mechanism of RNF11 on Akt signaling pathway, the 4th generation BMSCs were divided into Lv-NC transfection group (group A1), Lv-ShRNF11 transfection group (group B1), and Lv-ShRNF11 transfection supplemented with Akt signaling pathway activator SC79 group (group C1). The protein relative expressions of RNF11 and Akt signaling pathway were detected by Western blot, the related osteogenesis indexes were detected by Alizarin red staining, ALP staining, and qRT-PCR. The flow cytometry, and osteogenic, chondrogenic, adipogenic induction culture identification showed that the isolated and cultured cells were BMSCs. The protein relative expression of RNF11 increased gradually with the extension of osteogenic differentiation time ( P<0.05); after knockdown RNF11, Alizarin red and ALP stainings showed that the degree of osteogenic differentiation of BMSCs in group C were significantly lower than those in groups A and B, and qRT-PCR detection showed that the relative expression of Runx2, OCN, and OPN mRNA significantly decreased ( P<0.05). The protein relative expressions of RNF11 and Akt signaling pathway significantly increased with the extensions of osteogenic differentiation time ( P<0.05). After knockdown RNF11, the protein relative expression of Akt signaling pathway in group C was significantly lower than that in groups A and B ( P<0.05), while Smad1/5/8 and β-catenin signaling pathway had no significant effect ( P>0.05). Compared with group A1, the protein relative expression of RNF11 in groups B1 and C1 significantly decreased ( P<0.05). Compared with groups A1 and C1, the protein relative expression of Akt signaling pathway in group B1 was significantly lower ( P<0.05); Alizarin red and ALP stainings showed that the degree of osteogenic differentiation of BMSCs in group C1 were slightly lower than that of group A1 ( P>0.05), but significantly higher than that of group B1 ( P<0.05); qRT-PCR detection showed that the relative expressions of Runx2, OCN, and OPN mRNA in group C1 were slightly lower than those of group A1 ( P>0.05), but were significantly higher than those of group B1 ( P<0.05). RNF11 promotes the differentiation of BMSCs into osteoblasts by positively regulating the activation level of Akt signaling pathway. RNF11 can be used as a potential target to improve the bone repair efficacy of BMSCs and treat bone metabolic diseases.