LRP5-Mediated Lipid Uptake Modulates Osteogenic Differentiation of Bone Marrow Mesenchymal Stromal Cells

Semaglutide promotes the proliferation and osteogenic differentiation of bone-derived mesenchymal stem cells through activation of the Wnt/LRP5/β-catenin signaling pathway

Diabetes mellitus is a global disease in which alterations in the internal environment disrupt the bone-fat balance, contributing to osteoporosis. Semaglutide, a single-target, long-acting glucagon-like peptide-1 receptor agonist (GLP-1RA), has been shown to promote osteogenesis in vitro, but the underlying mechanism remains unclear. In this study, the ability of Semaglutide to promote the proliferation of bone-derived mesenchymal stem cells (BMSCs) was determined by CCK-8 kit and flow cytometry, Alkaline phosphatase (ALP) staining and alizarin red S staining showed that semaglutide increased ALP activity and the proportion of mineralised nodules during induction of osteogenesis, wound healing assay to evaluate the pro-migratory ability of semaglutide on BMSCs.Western blotting and RT-PCR showed that semaglutide promoted the mRNA and protein expression of osteocalcin (OCN) and Runt-related transcription factor 2 (RUNX2), and further determined the OCN expression level by immunofluorescence. RNA sequencing was performed to analyze the mechanisms underlying BMSC osteogenesis after semaglutide intervention. Enrichment of RNA sequencing data indicated that the Wnt/LRP5/β-catenin pathway was activated after treatment with semaglutide. Western blotting further confirmed the upregulation of Wnt pathway-associated protein levels by semaglutide. Dickkopf-1 (DKK1) and LiCl (lithium chloride) are common inhibitors and agonists of the Wnt/β-catenin pathway. The addition of semaglutide resulted in the partial reversal of the inhibitory effect of DKK1 on osteogenic differentiation, with the administration of LiCl and semaglutide further accelerating the osteogenic process. In addition to alterations in gene and protein expression levels, these changes are also reflected in alkaline phosphatase (ALP) activity and calcium deposition. Therefore, we suggest that semaglutide can promote the proliferation and osteogenic differentiation of BMSCs in vitro via the Wnt/LRP5/β-catenin signalling pathway.

tRNA-derived small RNA changes in bone marrow stem cells under hypoxia and osteogenic conduction

BACKGROUND

Tissue engineering using bone mesenchymal stem cells (BMSCs) transplantation is a promising therapeutic for bone regeneration. However, the effect of bone regeneration remains unsatisfactory due to the BMSCs' functional abnormality influenced by hypoxia. In this study, we attempt to explore the mechanism of osteogenic differentiation of BMSCs under hypoxic conditions from the perspective of non-coding RNA regulation.

METHODS

The study employed BMSCs obtained from healthy donors and simulated hypoxia using CoCl2 stimulation. High-throughput sequencing technique was used to identify differential expression profiles of tRNA-derived small RNA (tsRNA) in three experimental groups: BMSCs-0d, BMSCs-7d and BMSCs-0d-CoCl2 . TargetScan and miRanda algorithms were used to determine tsRNA target genes, while Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analysis were employed for the prediction of biological functions. Real-time reverse transcriptase-polymerase chain reaction (Real-time RT-PCR) was carried out on four selected differentially expressed tsRNAs.

RESULTS

After the osteogenic induction and CoCl2 stimulated separately, there were 19 tsRNAs differentially expressed in BMSCs, including 14 upregulated and five downregulated. According to the analysis of biological information, these tsRNAs may regulate 311 potential target genes and mainly enrich the pathways such as metabolic pathways, Wnt signalling pathway, osteoclast differentiation, cellular senescence and mTOR signalling pathway. The results of Real-time RT-PCR for 3'tiRNA-41-GlnTTG-6, 3'tiRNA-42-LysTTT-8, 5'tiRNA-35-CysACA-1 and tRF3a-AsnGTT-9 were consistent with small RNA sequencing data.

CONCLUSION

We discovered the tsRNA that changes the process of osteogenesis and hypoxia, which provides new targets for promoting survival and regeneration functions after BMSCs transplantation.

CircZNF367 suppresses osteogenic differentiation of human bone marrow mesenchymal stromal/stem cells via reducing HuR-mediated mRNA stability of LRP5

Osteoporosis is a highly prevalent disease characterized by bone mass loss and structural deterioration. There are evidences that altered differentiation of human bone marrow mesenchymal stromal/stem cells (hBMSCs) is a major cause for osteoporosis. Recent studies suggest that circular RNAs (circRNAs) are dysregulated in osteoporosis patients and involved in the pathogenesis of osteoporosis. In the present study, we are aimed to analyze the circRNA expression profiles in osteoporosis patients and identify potential circRNAs that involved in the differentiation of hBMSCs during osteoporosis. Transcriptome RNA-sequencing was conducted to search for differentially expressed circRNAs. Transwell assay, ARS and ALP staining, and ectopic bone formation model were performed to evaluate osteogenic differentiation of hBMSCs. RNA pull-down assay, RNA immunoprecipitation, western blot, and in vitro binding assay were conducted to evaluate the interaction of circRNAs and RNA-binding protein HuR. We found that hsa_circ_0008842 (designated as circZNF367) was upregulated in osteoporosis patients and decreased in hBMSCs during osteogenic differentiation. CircZNF367 overexpression suppressed migration, invasion and osteogenic differentiation of hBMSCs in vitro and in vivo. In comparison, knockdown of circZNF367 promoted migration, invasion and osteogenic differentiation of hBMSCs. CircZNF367 could interact with the RNA-binding protein HuR, thus reduced the mRNA stability of LRP5. Furthermore, HuR overexpression or LRP5 restoration abrogated the effects of circZNF367 overexpression on osteogenic differentiation of hBMSCs. Our results indicated that circZNF367 played a role in osteogenic differentiation of hBMSCs via reducing HuR-mediated mRNA stability of LRP5.