Bone marrow-derived mesenchymal stem cells (BMSCs) have been suggested to possess the capacity to differentiate into different cell lineages. Maintaining a balanced stem cell differentiation program is crucial to the bone microenvironment and bone development. MicroRNAs (miRNAs) have played a critical role in regulating the differentiation of BMSCs into particular lineage. However, the role of miR-149-3p in the adipogenic and osteogenic differentiation of BMSCs has not been extensively discovered. In this study, we aimed to detect the expression levels of miR-149-3p during the differentiation of BMSCs and investigate whether miR-149-3p participated in the lineage choice of BMSCs or not. Compared with mimic-negative control (NC), miR-149-3p mimic decreased the adipogenic differentiation potential of BMSCs and increased the osteogenic differentiation potential. Further analysis revealed that overexpression of miR-149-3p repressed the expression of fat mass and obesity-associated (FTO) gene through binding to the 3ʹ UTR of the FTO mRNA. Also, the role of miR-149-3p mimic in inhibiting adipogenic lineage differentiation and potentiating osteogenic lineage differentiation was mainly through targeting FTO, which also played an important role in regulating body weight and fat mass. In addition, BMSCs treated with miR-149-3p anti-miRNA oligonucleotide (AMO) exhibited higher potential to differentiate into adipocytes and lower tendency to differentiate into osteoblasts compared with BMSCs transfected with NC. In summary, our results detected the effects of miR-149-3p in cell fate specification of BMSCs and revealed that miR-149-3p inhibited the adipogenic differentiation of BMSCs via a miR-149-3p/FTO regulatory axis. This study provided cellular and molecular insights into the observation that miR-149-3p was a prospective candidate gene for BMSC-based bone tissue engineering in treating osteoporosis.

Bone marrow-derived mesenchymal stem cells (BMSCs) have the potential to differentiate into osteoblasts or adipocytes, and the shift between osteogenic and adipogenic differentiation determines bone mass. The aim of this study was to identify whether lncRNAs are involved in the differentiation commitment of BMSCs during osteoporosis. Here, we found ORLNC1, a functionally undefined lncRNA that is highly conserved, which exhibited markedly higher expression levels in BMSCs, bone tissue, and the serum of OVX-induced osteoporotic mice than sham-operated counterparts. Notably, a similar higher abundance of lncRNA-ORLNC1 expression was also observed in the bone tissue of osteoporotic patients. The transgenic mice overexpressing lncRNA-ORLNC1 showed a substantial increase in the osteoporosis-associated bone loss and decline in the osteogenesis of BMSCs. The BMSCs pretreated with lncRNA-ORLNC1-overexpressing lentivirus vector exhibited the suppressed capacity of osteogenic differentiation and oppositely enhanced adipogenic differentiation. We then established that lncRNA-ORLNC1 acted as a competitive endogenous RNA (ceRNA) for miR-296. Moreover, miR-296 was found markedly upregulated during osteoblast differentiation, and it accelerated osteogenic differentiation by targeting Pten. Taken together, our results indicated that the lncRNA-ORLNC1-miR-296-Pten axis may be a critical regulator of the osteoporosis-related switch between osteogenesis and adipogenesis of BMSCs and might represent a plausible therapeutic target for improving osteoporotic bone loss.

Osteoporosis is closely associated with the dysfunction of bone metabolism, which is caused by the imbalance between new bone formation and bone resorption. Osteogenic differentiation plays a vital role in maintaining the balance of bone microenvironment. The present study investigated whether melatonin participated in the osteogenic commitment of bone marrow mesenchymal stem cells (BMSCs) and further explored its underlying mechanisms. Our data showed that melatonin exhibited the capacity of regulating osteogenic differentiation of BMSCs, which was blocked by its membrane receptor inhibitor luzindole. Further study demonstrated that the expression of miR‐92b‐5p was up‐regulated in BMSCs after administration of melatonin, and transfection of miR‐92b‐5p accelerated osteogenesis of BMSCs. In contrast, silence of miR‐92b‐5p inhibited the osteogenesis of BMSCs. The increase in osteoblast differentiation of BMSCs caused by melatonin was attenuated by miR‐92b‐5p AMO as well. Luciferase reporter assay, real‐time qPCR analysis and western blot analysis confirmed that miR‐92b‐5p was involved in osteogenesis by directly targeting intracellular adhesion molecule‐1 (ICAM‐1). Melatonin improved the expression of miR‐92b‐5p, which could regulate the differentiation of BMSCs into osteoblasts by targeting ICAM‐1. This study provided novel methods for treating osteoporosis.

Influenza A viruses possess a high antigenic shift, and the approved anti-influenza drugs are extremely limited, which makes the development of novel anti-influenza drugs for the clinical treatment and prevention of influenza outbreaks imperative. Herein, we report a series of novel aryl benzoyl hydrazide analogs as potent anti-influenza agents. Particularly, analogs 10b, 10c, 10g, 11p, and 11q exhibited potent inhibitory activity against the avian H5N1 flu strain with EC50 values ranging from 0.009 to 0.034 μM. Moreover, compound 11q exhibited nanomolar antiviral effects against both the H1N1 virus and Flu B virus and possessed good oral bioavailability and inhibitory activity against influenza A virus in a mouse model. Preliminary mechanistic studies suggested that these compounds exert anti-influenza virus effects mainly by interacting with the PB1 subunit of RNA-dependent RNA polymerase (RdRp). These results revealed that 11q has the potential to become a potent clinical candidate to combat seasonal influenza and influenza pandemics.

Iron homeostasis is crucial for a variety of biological processes, but the biological role of iron homeostasis in pluripotent stem cells (PSCs) remains largely unknown. The present study aimed to determine whether iron homeostasis is involved in maintaining the pluripotency of human PSCs (hPSCs). We found that the intracellular depletion of iron leads to a rapid downregulation of NANOG and a dramatic decrease in the self-renewal of hPSCs as well as spontaneous and nonspecific differentiation. Moreover, long-term depletion of iron can result in the remarkable cell death of hPSCs via apoptosis and necrosis pathways. Additionally, we found that the depletion of iron increased the activity of lipoprotein-associated phospholipase A2 (LP-PLA2) and the production of lysophosphatidylcholine, thereby suppressing NANOG expression by enhancer of zeste homolog 2-mediated trimethylation of histone H3 lysine 27. Consistently, LP-PLA2 inhibition abrogated iron depletion-induced loss of pluripotency and differentiation. Altogether, the findings of our study demonstrates that iron homeostasis, acting through glycerophospholipid metabolic pathway, is essential for the pluripotency and survival of hPSCs. STEM CELLS 2019;37:489-503 SIGNIFICANCE STATEMENTIron homeostasis is essential for various biological processes. In this study, it was first demonstrated that iron deficiency could severely impair the pluripotency and differentiation of hESCs/ hiPSCs through the downregulation of NANOG by LysoPC-mediated H3K27me3. In addition, long-term iron deficiency reduced the survival and promoted apoptosis in hESCs/hiPSCs. Findings provide novel insights into the underlying mechanisms of iron homeostasis in maintaining the pluripotency and self-renewal of hESCs/hiPSCs