MiR-151b inhibits osteoblast differentiation via downregulating Msx2

Cell signaling and transcriptional regulation of osteoblast lineage commitment, differentiation, bone formation, and homeostasis

The initiation of osteogenesis primarily occurs as mesenchymal stem cells undergo differentiation into osteoblasts. This differentiation process plays a crucial role in bone formation and homeostasis and is regulated by two intricate processes: cell signal transduction and transcriptional gene expression. Various essential cell signaling pathways, including Wnt, BMP, TGF-β, Hedgehog, PTH, FGF, Ephrin, Notch, Hippo, and Piezo1/2, play a critical role in facilitating osteoblast differentiation, bone formation, and bone homeostasis. Key transcriptional factors in this differentiation process include Runx2, Cbfβ, Runx1, Osterix, ATF4, SATB2, and TAZ/YAP. Furthermore, a diverse array of epigenetic factors also plays critical roles in osteoblast differentiation, bone formation, and homeostasis at the transcriptional level. This review provides an overview of the latest developments and current comprehension concerning the pathways of cell signaling, regulation of hormones, and transcriptional regulation of genes involved in the commitment and differentiation of osteoblast lineage, as well as in bone formation and maintenance of homeostasis. The paper also reviews epigenetic regulation of osteoblast differentiation via mechanisms, such as histone and DNA modifications. Additionally, we summarize the latest developments in osteoblast biology spurred by recent advancements in various modern technologies and bioinformatics. By synthesizing these insights into a comprehensive understanding of osteoblast differentiation, this review provides further clarification of the mechanisms underlying osteoblast lineage commitment, differentiation, and bone formation, and highlights potential new therapeutic applications for the treatment of bone diseases.

Function and regulation of miR-186-5p, miR-125b-5p and miR-1260a in chordoma

BACKGROUND

The function and regulation of miRNAs in progression of chordoma were unclear.

METHODS

Five miRNAs were identified by the machine learning method from the miRNA expression array. CCk-8 assay, EDU assay, wound healing migration assay, and trans-well assay were used to reveal the effect of the miRNAs in chordoma cell lines. Moreover, bioinformation analysis and the mRNA expression array between the primary chordomas and recurrent chordomas were used to find the target protein genes of miRNAs. Furthermore, qRT-PCR and luciferase reporter assay were used to verify the result.

RESULTS

miR-186-5p, miR-30c-5p, miR-151b, and miR-125b-5p could inhibit proliferation, migration, and invasion of chordoma while miR-1260a enhances proliferation, migration, and invasion of chordoma. Recurrent chordoma has a worse disease-free outcome than the primary chordoma patients. AMOT, NPTX1, RYR3, and P2RX5 were the target protein mRNAs of miR-186-5p; NPTX1 was the target protein mRNAs of miR-125b-5p; and AMOT and TNFSF14 were the target protein mRNAs of miR-1260a.

CONCLUSIONS

miR-186-5p, miR-125b-5p, miR-1260a, and their target protein mRNAs including AMOT, NPTX1, RYR3, P2RX5, TNFSF14 may be the basement of chordoma research.

Circulating MicroRNAs as Biomarkers of Osteoporosis and Fragility Fractures

CONTEXT

Measurement of circulating microRNAs (miRNAs) as potential biomarkers of fragility fracture risk has recently become a subject of investigation.

OBJECTIVE

Measure by next-generation sequencing (NGS), global miRNA expression in serum samples of osteoporotic subjects vs individuals with normal bone mineral density (BMD).

DESIGN

Samples were collected from patients with different bone phenotypes and/or fragility fractures who did not receive any antiresorptive and/or bone-forming drug at the time of blood collection.

SETTING

Samples and data were collected at 7 medical centers in Italy.

PATIENTS

NGS prescreening: 50 osteoporotic patients vs 30 individuals with normal BMD. Droplet digital polymerase chain reaction (ddPCR) validation: 213 patients with different bone phenotypes, including the NGS-analyzed cohort.

RESULTS

NGS identified 5 miRNAs (miR-8085, miR-320a-3p, miR-23a-3p, miR-4497, miR-145-5p) differentially expressed in osteoporosis cases without fractures vs controls. ddPCR validation confirmed lower c-miR-23a-3p expression in osteoporotic patients, with or without fracture, than in osteopenic and normal subjects and increased c-miR-320a-3p expression in osteoporotic patients with fracture and lower expression in osteoporotic patients without fracture. ddPCR analysis showed a significantly increased expression of miR-21-5p in osteoporotic patients, with or without fracture, than in osteopenic and normal subjects, not evidenced by the NGS prescreening.

DISCUSSION

Our study confirmed levels of c-miR-23a-3p and c-miR-21-5p as able to distinguish osteoporotic patients and subjects with normal BMD. Increased levels of c-miR-320a-3p specifically associated with fractures, independently by BMD, suggesting c-miR-320a-3p as a prognostic indicator of fracture risk in osteoporotic patients, to be confirmed in prospective studies on incident fractures.

lncRNA IGF2-AS promotes the osteogenic differentiation of bone marrow mesenchymal stem cells by sponging miR-3,126-5p to upregulate KLK4

BACKGROUND

Osteoporosis (OP) is a bone disease characterized by reduced amount and quality of bone. This study was designed to explore the role and mechanism of lncRNA IGF2-AS in the osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs).

METHODS

Human lncRNA and miRNA microarray analyses were performed to measure the differential expression levels of lncRNAs and miRNAs in undifferentiated and osteogenically differentiated BMSCs. lncRNA IGF2-AS, miR-3,126-5p, and KLK4 levels were measured by real-time quantitative polymerase chain reaction (RT-qPCR). Osteogenic differentiation of BMSCs was assessed by alkaline phosphatase (ALP) staining and Alizarin Red staining (ARS). Protein levels of osterix (Osx), osteocalcin (OCN), and runt-related transcription factor 2 (RUNX2) were examined by RT-PCR and western blot assays. The binding relationship between miR-3,126-5p and lncRNA IGF2-AS or KLK4 was predicted by TargetScan (http://www.targetscan.org/vert_72/) and then verified with a dual-luciferase reporter assay.

RESULTS

lncRNA IGF2-AS and KLK4 were highly expressed and miR-3,126-5p was weakly expressed in osteogenically differentiated BMSCs. Moreover, lncRNA IGF2-AS overexpression enhanced the osteogenic differentiation of BMSCs. In contrast, lncRNA IGF2-AS knockdown showed the opposite trend. Moreover, miR-3,126-5p overexpression abolished the lncRNA IGF2-AS-mediated osteogenic differentiation of BMSCs. lncRNA IGF2-AS functions as a sponge of miR-3,126-5p to regulate KLK4 expression.

CONCLUSION

lncRNA IGF2-AS enhances the osteogenic differentiation of BMSCs by modulating the miR-3,126-5p/KLK4 axis, suggesting a promising therapeutic target for bone-related diseases.