Expression of lncRNA MALAT1 through miR-144-3p in Osteoporotic Tibial Fracture Rats and Its Effect on Osteogenic Differentiation of BMSC under Traction

Abstract

Objective. To investigate the expression of lncRNA MALAT1 and miR-144-3p in osteoporotic (OP) tibial fracture rats and analyze their targeting relationship and effects on the osteogenic differentiation of bone marrow mesenchymal stem cells (BMSC) under traction. Methods. The OP tibial fracture model was established, and the rats were divided into a sham group and a model group. The tibial tissue of these rats was taken. BMSC of cultured rats with good growth was purchased and grouped according to the presence or absence of transfection of si-MALAT1 and miR-144-3p-mimic. The expression of MALAT1 and miR-144-3p in each group was detected. The bioinformatics website and double luciferase were used to predict the targeting relationship between MALAT1 and miR-144-3p and to detect the expression of genes related to bone differentiation (collagen I, osteocalcin (OCN), osteopontin (OPN), and alkaline phosphatase (ALP)) of each component, and ALP staining and AR staining were used to detect the formation of BMSC calcium nodules. Results. The levels of ALP and TRAP in the model group were higher than that in the sham group ( $P<0.05$ ). qRT-PCR results showed that the relative expression level of MALAT1 in the model group was higher than that in the sham group, and the relative expression level of miR-144-3p was lower than that in the sham group ( $P<0.05$ ). MALAT1 has a targeting relationship with miR-144-3p. qRT-PCR results showed that the relative expression level of MALAT1 in the tension-MSC group was higher than the MSC group, and the relative expression level of miR-144-3p was lower than the MSC group ( $P<0.05$ ). The expressions of collagen I, OCN, OPN, and ALP proteins in the si-MALAT1 group were higher than those of the si-NC group ( $P<0.05$ ). The results of ALP staining showed that BMSCs of the si-MALAT1 group had stronger osteogenic differentiation capacity and higher ALP activity than those of the si-NC group. The results of AR staining showed that compared with the si-NC group, the mineralization degree of cells in the si-MALAT1 group was higher, the number of calcium nodules was more, and the cells were more deeply stained. The expressions of collagen I, OCN, OPN, and ALP proteins in the miR-144-3p-mimic group were higher than the mimic-NC group ( $P<0.05$ ). ALP staining results showed that BMSCs in the miR-144-3p-mimic group had strong osteogenic differentiation capacity and high ALP activity compared with the mimic-NC group. The results of AR staining showed that, compared with the mimic-NC group, the mineralization degree of cells in the miR-144-3p-mimic group was higher, the number of calcium nodules was more and the cells were more deeply stained. Conclusion. In the OP rat model with the tibial fracture, the expression of MALAT1 is upregulated and that of miR-144-3p is downregulated. MALAT1 has a targeting relationship with miR-144-3p, and downregulation of MALAT1 and upregulation of miR-144-3p can promote the osteogenic differentiation of BMSC under traction.