Erratum to "MiRNA-10b Reciprocally Stimulates Osteogenesis and Inhibits Adipogenesis Partly through the TGF-ß/SMAD2 Signaling Pathway".

[This corrects the article on p. 1058 in vol. 9, PMID: 30574418.].

MiRNA-10b Reciprocally Stimulates Osteogenesis and Inhibits Adipogenesis Partly through the TGF-ß/SMAD2 Signaling Pathway.

As the population ages, the medical and socioeconomic impact of age-related bone disorders will further increase. An imbalance between osteogenesis and adipogenesis of mesenchymal stem cells (MSCs) can lead to various bone and metabolic diseases such as osteoporosis. Thus, understanding the molecular mechanisms underlying MSC osteogenic and adipogenic differentiation is important for the discovery of novel therapeutic paradigms for these diseases. miR-10b has been widely reported in tumorigenesis, cancer invasion and metastasis. However, the effects and potential mechanisms of miR-10b in the regulation of MSC adipogenic and osteogenic differentiation have not been explored. In this study, we found that the expression of miR-10b was positively correlated with bone formation marker genes ALP, RUNX2 and OPN, and negatively correlated with adipogenic markers CEBPα, PPARγ and AP2 in clinical osteoporosis samples. Overexpression of miR-10b enhanced osteogenic differentiation and inhibited adipogenic differentiation of human adipose-derived mesenchymal stem cells (hADSCs) in vitro, whereas downregulation of miR-10b reversed these effects. Furthermore, miR-10b promoted ectopic bone formation in vivo. Target prediction and dual luciferase reporter assays identified SMAD2 as a potential target of miR-10b. Silencing endogenous SMAD2 expression in hADSCs enhanced osteogenesis but repressed adipogenesis. Pathway analysis indicated that miR-10b promotes osteogenic differentiation and bone formation via the TGF-ß signaling pathway, while suppressing adipogenic differentiation may be primarily mediated by other pathways. Taken together, our findings imply that miR-10b acts as a critical regulator for balancing osteogenic and adipogenic differentiation of hADSCs by repressing SMAD2 and partly through the TGF-ß pathway. Our study suggests that miR-10b is a novel target for controlling bone and metabolic diseases.

Generation of Functional Hepatocytes from Human Adipose-Derived MYC+ KLF4+ GMNN+ Stem Cells Analyzed by Single-Cell RNA-Seq Profiling.

Cell transplantation holds considerable promise for end-stage liver diseases but identifying a suitable, transplantable cell type has been problematic. Here, we describe a novel type of mesenchymal stem cells (MSCs) from human adipose tissue. These cells are different from previously reported MSCs, they are in the euchromatin state with epigenetic multipotency, and express pluripotent markers MYC, KLF4, and GMNN. Most of the genes associated with germ layer specification are modified by H3K4me3 or co-modified by H3K4me3 and H3K27me3. We named this new type of MSCs as adult multipotent adipose-derived stem cells (M-ADSCs). Using a four-step nonviral system, M-ADSCs can be efficiently Induced into hepatocyte like cells with expression of hepatocyte markers, drug metabolizing enzymes and transporters, and the other basic functional properties including albumin (ALB) secretion, glycogen storage, detoxification, low-density lipoprotein intake, and lipids accumulation. In vivo both M-ADSCs-derived hepatoblasts and hepatocytes could form vascularized liver-like tissue, secrete ALB and express metabolic enzymes. Single-cell RNA-seq was used to investigate the important stages in this conversion. M-ADSCs could be converted to a functionally multipotent state during the preinduction stage without undergoing reprogramming process. Our findings provide important insights into mechanisms underlying cell development and conversion. Stem Cells Translational Medicine 2018;7:792-805.

miR-450b Promotes Osteogenic Differentiation In Vitro and Enhances Bone Formation In Vivo by Targeting BMP3.

Osteoporosis is characterized by deterioration of bone microarchitecture and low bone mass. One of the primary causes of osteoporosis is the decrease in the osteogenic differentiation of mesenchymal stem cells (MSCs). Tissue engineering therapy with genetically modified MSCs has attracted much attention in the study of bone regeneration. In this study, we found that the expression level of miR-450b was upregulated during osteogenic differentiation of human adipose-derived mesenchymal stem cells (hADSCs). To explore the effect of miR-450b on the osteogenesis of hADSCs, we performed a series of gain- and loss-of-function analyses and demonstrated that miR-450b not only promoted the process of hADSC differentiation to osteoblasts in vitro but also enhanced ectopic bone formation in vivo. Bone morphogenetic protein 3 (BMP3), the most abundant BMP member in bone, was identified as a direct target of miR-450b. Downregulation of the endogenous expression of BMP3 could mimic the effect of miR-450b upregulation on the osteogenic differentiation of hADSCs. Overall, our study first demonstrated that a novel microRNA miR-450b was essential for hADSC differentiation, which could promote osteogenic differentiation in vitro and enhance bone formation in vivo by directly suppressing BMP3.

microRNA-23a inhibits osteogenic differentiation of human bone marrow-derived mesenchymal stem cells by targeting LRP5.

Emerging evidence indicates that microRNAs (miRNA, or miR) play vital roles in regulating osteogenic differentiation of bone marrow-derived mesenchymal stem cells (BMSCs). Elucidation of the molecular mechanisms that govern BMSCs osteogenic differentiation is of paramount importance for improving the treatment of bone-related diseases. In our current study, we investigated the role of miR-23a in BMSCs osteogenesis. Our results revealed that miR-23a was significantly downregulated during osteogenic differentiation. Overexpression of miR-23a inhibited osteogenic differentiation of hBMSCs in vitro, whereas downregulation of miR-23a enhanced the process. Target prediction analysis and dual luciferase reporter assays confirmed that low-density lipoprotein (LDL)-receptor-related protein 5 (LRP5) was a direct target of miR-23a. Furthermore, knockdown of LRP5 inhibited osteogenic differentiation of hBMSCs, similar to the effect observed in upregulation miR-23a. Our data indicate that miR-23a plays an inhibitory role in osteogenic differentiation of hBMSCs, which may act by targeting LRP5.

Long Noncoding RNA ADINR Regulates Adipogenesis by Transcriptionally Activating C/EBPα.

C/EBPα is a critical transcriptional regulator of adipogenesis. How C/EBPα transcription is itself regulated is poorly understood, however, and remains a key question that needs to be addressed for a complete understanding of adipogenic development. Here, we identify a lncRNA, ADINR (adipogenic differentiation induced noncoding RNA), transcribed from a position ∼450 bp upstream of the C/EBPα gene, that orchestrates C/EBPα transcription in vivo. Depletion of ADINR leads to a severe adipogenic defect that is rescued by overexpression of C/EBPα. Moreover, we reveal that ADINR RNA specifically binds to PA1 and recruits MLL3/4 histone methyl-transferase complexes so as to increase H3K4me3 and decrease H3K27me3 histone modification in the C/EBPα locus during adipogenesis. These results show that ADINR plays important roles in regulating the differentiation of human mesenchymal stem cells into adipocytes by modulating C/EBPα in cis.

MicroRNA expression profile of dexamethasone-induced human bone marrow-derived mesenchymal stem cells during osteogenic differentiation.

MiRNAs have been identified in various plants and animals where they function in post-transcriptional regulation. Although studies revealed that dexamethasone play a pivotal role in the osteogenic differentiation of human bone marrow-derived mesenchymal stem cells (hBMSCs), the identification of specific miRNAs and their regulatory roles in this process remain poorly defined. In this study, microarrays were used to analyze the miRNA expression profile of dexamethasone-induced hBMSCs derived from three donors, and RT-PCRs were used to confirm the microarray results. Nine upregulated miRNAs and seven downregulated miRNAs were identified. The putative target genes of these miRNAs were predicted using bioinformatics analysis. Subsequently, we focused our attention on the functional analysis of an upregulated miRNA, miR-23a. Overexpression of miR-23a inhibited osteogenic differentiation of hBMSCs at the cellular, mRNA, and protein levels. The results of our study provide an experimental basis for further research on miRNAs functions during osteogenic differentiation of dexamethasone-induced hBMSCs.

let-7 enhances osteogenesis and bone formation while repressing adipogenesis of human stromal/mesenchymal stem cells by regulating HMGA2.

Bone and fat cells share a common progenitor, stromal/mesenchymal stem cells (MSCs), that can differentiate into osteoblasts or adipocytes. Osteogenesis and adipogenesis of MSCs maintain homeostasis under physiological conditions. The disruption of this homeostasis leads to bone-related metabolic diseases. For instance, reduction in bone formation, which is usually accompanied by an increase in bone marrow adipogenesis, occurs with aging, immobility, or osteoporosis. Thus, it is crucial to gain an understanding of how osteogenic and adipogenic lineages of MSCs are regulated. Here, we present evidence that let-7 is a positive regulator of bone development. Using gain- and loss-of-function approaches, we demonstrate that let-7 markedly promotes osteogenesis and suppresses adipogenesis of MSCs in vitro. Moreover, let-7 could promote ectopic bone formation of MSCs in vivo. Subsequent studies further demonstrated that let-7's effects are mediated through the repression of high-mobility group AT-hook 2 (HMGA2) expression. RNAi depletion of HMGA2 could also enhance osteogenesis and repress adipogenesis. Overall, we found a novel role of let-7/HMGA2 axis in regulating the balance of osteogenesis and adipogenesis of MSCs. Thus, let-7 can be used as a novel therapeutic target for disorders that are associated with bone loss and adipocyte accumulation.

miR-17-5p and miR-106a are involved in the balance between osteogenic and adipogenic differentiation of adipose-derived mesenchymal stem cells.

Mesenchymal stem cells (MSCs) can differentiate into several distinct cell types, including osteoblasts and adipocytes. The balance between osteogenic and adipogenic differentiation is disrupted in several osteogenic-related disorders, such as osteoporosis. So far, little is known about the molecular mechanisms that drive final lineage commitment of MSCs. In this study, we revealed that miR-17-5p and miR-106a have dual functions in the modulation of human adipose-derived mesenchymal stem cells (hADSCs) commitment by gain- and loss-of-function assays. They could promote adipogenesis and inhibit osteogenesis. Luciferase reporter assay, western blot and ELISA suggested BMP2 was a direct target of miR-17-5p and miR-106a. Downregulation of endogeneous BMP2 by RNA interference suppressed osteogenesis and increased adipogenesis, similar to the effect of miR-17-5p and miR-106a upregulation. Moreover, the inhibitory effects of miR-17-5p on osteogenic and adipogenic differentiation of hADSCs could be reversed by BMP2 RNA interference. In conclusion, miR-17-5p and miR-106a regulate osteogenic and adipogenic lineage commitment of hADSCs by directly targeting BMP2, and subsequently decreased osteogenic TAZ, MSX2 and Runx2, and increased adipogenic C/EBPα and PPARγ.