Over-expression of MEG3 promotes differentiation of bone marrow mesenchymal stem cells into chondrocytes by regulating miR-129-5p/RUNX1 axis

Long non-coding RNA MIR22HG suppresses the chondrogenic differentiation of human adipose-derived stem cells by interacting with CTCF to upregulate CRLF1

Improved chondrogenic differentiation of mesenchymal stem cells (MSCs) by genetic regulation is a potential method for regenerating articular cartilage. LncRNA MIR22HG has been proven to accelerate osteogenic differentiation, but the regulation mechanism of chondrogenic differentiation is still unclear. Human adipose-derived stem cells (hADSCs) have been widely utilised for bone tissue engineering applications. The present study aimed to examine the effect of MIR22HG on the chondrogenic differentiation of hADSCs. The results confirmed that MIR22HG was downregulated in the process of chondrogenic differentiation. Subsequently, gain- and loss-of-function of MIR22HG experiments showed that the overexpression of MIR22HG suppressed the deposition of cartilage matrix proteoglycans and decreased the expression of cartilage-related markers (e.g. Sox9, ACAN and Col2A1), whereas the knockdown of MIR22HG had the opposite effect. MIR22HG could bind to CTCF (CCCTC-binding factor), and CTCF could bind to the CRLF1 (cytokine receptor-like factor 1) promoter and upregulate CRLF1 gene expression. Besides, inhibition of CRLF1 can reverse the effect of MIR22HG on cell chondrogenic differentiation of hADSCs. Taken together, our outcomes reveal that MIR22HG suppressed chondrogenic differentiation by interaction with CTCF to stabilise CRLF1.

lncRNA MALAT1 mediates osteogenic differentiation of bone mesenchymal stem cells by sponging miR-129-5p

Background

Bone mesenchymal stem cells (BMSCs) have good osteogenic differentiation potential and have become ideal seed cells in bone tissue engineering. However, the osteogenic differentiation ability of BMSCs gradually weakens with age, and the regulatory mechanism is unclear.

Method

We conducted a bioinformatics analysis, dual-luciferase reporter (DLR) experiment, and RNA binding protein immunoprecipitation (RIP) to explore the hub genes that may affect BMSC functions.

Results

The expression level of long non-coding RNA (lncRNA) metastasis-associated lung adenocarcinoma transcript 1 (Malat1) was significantly higher in the BMSCs from elderly than younger mice, while miR-129-5p showed the opposite trend. The results of alkaline phosphatase staining, quantitative reverse transcription PCR and western blot experiments indicated that inhibiting the expression of Malat1 inhibits the osteogenic differentiation of BMSCs. This effect can be reversed by reducing the expression of miR-129-5p. Additionally, DLR and RIP experiments confirmed that Malat1 acts as a sponge for miR-129-5p.

Conclusion

Overall, our study findings indicated that lncRNA Malat1 may play a critical role in maintaining the osteoblast differentiation potential of BMSCs by sponging miR-129-5p.

[Effect of LOC103693069 on hypoxic apoptosis of bone marrow mesenchymal stem cells]

OBJECTIVE

To investigate the effect of LOC103693069 on hypoxic apoptosis of bone marrow mesenchymal stem cells (BMSCs).

METHODS

BMSCs from 1-week-old Sprague Dawley rat bone marrow were isolated, cultured, and passaged by the whole bone marrow adherent culture method. After identification of adipogenic, chondrogenic, and osteogenic differentiation, the 3rd generation cells were treated with hypoxia under 5%O ₂, 1%O ₂, and anaerobic conditions. After 48 hours, the cell viability, apoptosis, and apoptosis-related proteins [hypoxia inducible factor 1α (HIF-1α), Caspase-3, B cell lymphoma/leukemia 2 (Bcl-2)] expressions were detected, and normal BMSCs were used as controls. Based on the research results, the concentration group with the most obvious apoptosis was selected and used for subsequent experiments. After 48 hours of hypoxia treatment, BMSCs were taken and analyzed by gene chip and real-time fluorescence quantitative PCR (qRT-PCR) to screen the most significantly down-regulated gene and construct their high-expression, low-expression, and negative control lentiviruses; BMSCs were transfected with the different lentiviruses, respectively. After qRT-PCR detection confirmed that the transfection was successful, the BMSCs were treated with hypoxia for 48 hours to observe the cell viability and the expressions of apoptosis-related proteins.

RESULTS

After cell viability, apoptosis, and apoptosis-related proteins were detected, cell apoptosis was the most significant under anaerobic conditions after 48 hours. The above indicators were significantly different from other groups ( P<0.05), and this group was used for treatment conditions for subsequent experiments. Gene chip analysis showed that after 48 hours of hypoxia treatment, AC125847.1, LOC102547753, AABR07017208.2, and LOC103693069 were significantly down-regulated in BMSCs, and the expressions of LOC103693069 was the most significant down-regulation detected by qRT-PCR ( P<0.05). It was selected to construct lentivirus and transfect BMSCs. Afterwards, qRT-PCR detection showed the successful transfection into the cells. After hypoxia treatment, the apoptosis rate and the expressions of apoptosis-related proteins of BMSCs overexpressed by the gene were significantly reduced ( P<0.05).

CONCLUSION

LOC103693069 can relieve the hypoxic apoptosis of BMSCs.

FoxO3a cooperates with RUNX1 to promote chondrogenesis and terminal hypertrophic of the chondrogenic progenitor cells

FoxO transcription factors (FoxOs) have recently been shown to protect against chondrocyte dysfunction and modulate cartilage homeostasis in osteoarthritis. The mechanism underlying of FoxOs regulate chondrocyte differentiation remains unknown. Runt related transcription factor 1 (RUNX1) mediated both chondrocyte and osteoblast differentiation. Our data showed that FoxO3a and RUNX1 are co-expressed in ATDC5 cells and undifferentiated mesenchyme cells and have similar high levels in chondrocytes undergoing transition from proliferation to hypertrophy. Overexpression of FoxO3a in ATDC5 cells or mouse mesenchymal cells resulted in a potent induction of the chondrocyte differentiation markers. Knockdown FoxO3a or RUNX1 potently inhibits the expressions of chondrocyte differentiation markers, including Sox9, Aggrecan, Col2, and hypertrophic chondrocyte markers including RUNX2, ColX, MMP13 and ADAMTs-5 in ATDC5 cells. Co-immunoprecipitation showed that FoxO3a binds the transcriptional regulator RUNX1. Immunohistochemistry showed that FoxO3a and RUNX1 are highly co-expressed in the proliferative chondrocytes of the growth plates in the hind limbs of newborn mice. Collectively, we revealed that FoxO3a cooperated with RUNX1 promoted chondrocyte differentiation through enhancing both early chondrogenesis and terminal hypertrophic of the chondrogenic progenitor cells, indicating FoxO3a interacting with RUNX1 may be a therapeutic target for the treatment of osteoarthritis and other bone diseases.

Long Non-Coding RNA MEG3 in Cellular Stemness

Long non-coding RNAs (lncRNAs) regulate a diverse array of cellular processes at the transcriptional, post-transcriptional, translational, and post-translational levels. Accumulating evidence suggests that lncRNA MEG3 exerts a large repertoire of regulatory functions in cellular stemness. This review focuses on the molecular mechanisms by which lncRNA MEG3 functions as a signal, scaffold, guide, and decoy for multi-lineage differentiation and even cancer progression. The role of MEG3 in various types of stem cells and cancer stem cells is discussed. Here, we provide an overview of the functional versatility of lncRNA MEG3 in modulating pluripotency, differentiation, and cancer stemness.