Fate Of Mesenchymal Stem Cells Research Articles

Mettl3-mediated m6A RNA methylation regulates the fate of bone marrow mesenchymal stem cells and osteoporosis

N6-methyladenosine (m6A) is the most abundant epigenetic modification in eukaryotic mRNAs and is essential for multiple RNA processing events during mammalian development and disease control. Here we show that conditional knockout of the m6A methyltransferase Mettl3 in bone marrow mesenchymal stem cells (MSCs) induces pathological features of osteoporosis in mice. Mettl3 loss-of-function results in impaired bone formation, incompetent osteogenic differentiation potential and increased marrow adiposity. Moreover, Mettl3 overexpression in MSCs protects the mice from estrogen deficiency-induced osteoporosis. Mechanistically, we identify PTH (parathyroid hormone)/Pth1r (parathyroid hormone receptor-1) signaling axis as an important downstream pathway for m6A regulation in MSCs. Knockout of Mettl3 reduces the translation efficiency of MSCs lineage allocator Pth1r, and disrupts the PTH-induced osteogenic and adipogenic responses in vivo. Our results demonstrate the pathological outcomes of m6A mis-regulation in MSCs and unveil novel epitranscriptomic mechanism in skeletal health and diseases.

MiR-130a and miR-27b Enhance Osteogenesis in Human Bone Marrow Mesenchymal Stem Cells via Specific Down-Regulation of Peroxisome Proliferator-Activated Receptor γ.

Mesenchymal stem cell (MSC) is a type of stem cell that is capable of differentiating into osteoblasts and adipocytes. The pathological perturbation of MSC fate determination is well demonstrated by the replacement of bone tissues with fat in those with osteoporosis and osteopenia. Cell fate determination can be regulated by epigenetic and post-transcriptional mechanisms. MicroRNAs (miRNAs) are small endogenous non-coding RNA molecules that mediates the post-transcriptional regulation of genes expression. We hypothesized that miRNA specified to PPARγ, a major transcription factor of adipogenesis, is responsible for the differentiation of MSCs into osteoblasts. Candidate miRNA that is responsible for target gene inhibition was identified from the miRNA database via bioinformatic analyses. In this study, miR-130a and miR-27b were selected for investigation on their role in specifically binding to peroxisome proliferator-activated receptor γ (PPARγ) via in vitro osteogenesis of human MSCs. During osteogenic differentiation of human MSCs, the expression level of miR-130a and miR-27b were found to be upregulated. In the meanwhile, adipogenic marker genes (PPARγ and C/EBPβ) were found to decrease, which is in contrary to the increased expression of osteogenic marker genes (RUNX2 and Osterix). MSCs were transfected with mimics and inhibitors of miR-130a and miR-27b during in vitro osteogenesis followed by evaluation for the presence of osteogenic markers via quantitative gene expression, Western blot analysis and alkaline phosphatase activity assay. The overexpression of miR-130a and miR-27b is shown to enhance osteogenesis by increasing the gene expression of RUNX2 and Osterix, the protein expression of RUNX2, COL1A1, and Osterix as well as the alkaline phosphatase activity. Taken altogether, these results suggested that miR-130a and miR-27b could promote osteogenesis in human MSCs by targeting the PPARγ.

H3K36 trimethylation mediated by SETD2 regulates the fate of bone marrow mesenchymal stem cells.

During the aging process, bone marrow mesenchymal stem cells (BMSCs) exhibit declined osteogenesis accompanied by excess adipogenesis, which will lead to osteoporosis. Here, we report that the H3 lysine 36 trimethylation (H3K36me3), catalyzed by histone methyltransferase SET-domain-containing 2 (SETD2), regulates lineage commitment of BMSCs. Deletion of Setd2 in mouse bone marrow mesenchymal stem cells (mBMSCs), through conditional Cre expression driven by Prx1 promoter, resulted in bone loss and marrow adiposity. Loss of Setd2 in BMSCs in vitro facilitated differentiation propensity to adipocytes rather than to osteoblasts. Through conjoint analysis of RNA sequencing (RNA-seq) and chromatin immunoprecipitation sequencing (ChIP-seq) data, we identified a SETD2 functional target gene, Lbp, on which H3K36me3 was enriched, and its expression was affected by Setd2 deficiency. Furthermore, overexpression of lipopolysaccharide-binding protein (LBP) could partially rescue the lack of osteogenesis and enhanced adipogenesis resulting from the absence of Setd2 in BMSCs. Further mechanistic studies demonstrated that the trimethylation level of H3K36 could regulate Lbp transcriptional initiation and elongation. These findings suggest that H3K36me3 mediated by SETD2 could regulate the cell fate of mesenchymal stem cells (MSCs) in vitro and in vivo, indicating that the regulation of H3K36me3 level by targeting SETD2 and/or the administration of downstream LBP may represent a potential therapeutic way for new treatment in metabolic bone diseases, such as osteoporosis.

Long noncoding RNA Bmncr regulates mesenchymal stem cell fate during skeletal aging.

Bone marrow mesenchymal stem cells (BMSCs) exhibit an age-related lineage switch between osteogenic and adipogenic fates, which contributes to bone loss and adiposity. Here we identified a long noncoding RNA, Bmncr, which regulated the fate of BMSCs during aging. Mice depleted of Bmncr (Bmncr-KO) showed decreased bone mass and increased bone marrow adiposity, whereas transgenic overexpression of Bmncr (Bmncr-Tg) alleviated bone loss and bone marrow fat accumulation. Bmncr regulated the osteogenic niche of BMSCs by maintaining extracellular matrix protein fibromodulin (FMOD) and activation of the BMP2 pathway. Bmncr affected local 3D chromatin structure and transcription of Fmod. The absence of Fmod modified the bone phenotype of Bmncr-Tg mice. Further analysis revealed that Bmncr would serve as a scaffold to facilitate the interaction of TAZ and ABL, and thus facilitate the assembly of the TAZ and RUNX2/PPARG transcriptional complex, promoting osteogenesis and inhibiting adipogenesis. Adeno-associated viral-mediated overexpression of Taz in osteoprogenitors alleviated bone loss and marrow fat accumulation in Bmncr-KO mice. Furthermore, restoring BMNCR levels in human BMSCs reversed the age-related switch between osteoblast and adipocyte differentiation. Our findings indicate that Bmncr is a key regulator of the age-related osteogenic niche alteration and cell fate switch of BMSCs.

Three-Dimensional Nanostructured Architectures Enable Efficient Neural Differentiation of Mesenchymal Stem Cells via Mechanotransduction.

Cell morphology and geometry affect cellular processes such as stem cell differentiation, suggesting that these parameters serve as fundamental regulators of biological processes within the cell. Hierarchical architectures featuring micro- and nanotopographical features therefore offer programmable systems for stem cell differentiation. However, a limited number of studies have explored the effects of hierarchical architectures due to the complexity of fabricating systems with rationally tunable micro- and nanostructuring. Here, we report three-dimensional (3D) nanostructured microarchitectures that efficiently regulate the fate of human mesenchymal stem cells (hMSCs). These nanostructured architectures strongly promote cell alignment andefficient neurogenic differentiation where over 85% of hMSCs express microtubule-associated protein 2 (MAP2), a mature neural marker, after 7 days of culture on the nanostructured surface. Remarkably, we found that the surface morphology of nanostructured surface is a key factor that promotes neurogenesis and that highly spiky structures promote more efficient neuronal differentiation. Immunostaining and gene expression profiling revealed significant upregulation of neuronal markers compared to unpatterned surfaces. These findings suggest that the 3D nanostructured microarchitectures can play a critical role in defining stem cell behavior.

Epigenetic Control of Mesenchymal Stem Cell Fate Decision via Histone Methyltransferase Ash1l.

Previous research indicates that knocking out absent, small, or homeotic-like (Ash1l) in mice, a histone 3 lysine 4 (H3K4) trimethyltransferase, can result in arthritis with more severe cartilage and bone destruction. Research has documented the essential role of Ash1l in stem cell fate decision such as hematopoietic stem cells and the progenitors of keratinocytes. Following up on those insights, our research seeks to document the function of Ash1l in skeletal formation, specifically whether it controls the fate decision of mesenchymal progenitor cells. Our findings indicate that in osteoporotic bones, Ash1l was significantly decreased, indicating a positive correlation between bone mass and the expression of Ash1l. Silencing of Ash1l that had been markedly upregulated in differentiated C3H10T1/2 (C3) cells hampered osteogenesis and chondrogenesis but promoted adipogenesis. Consistently, overexpression of an Ash1l SET domain-containing fragment 3 rather than Ash1lΔN promoted osteogenic and chondrogenic differentiation of C3 cells and simultaneously inhibited adipogenic differentiation. This indicates that the role of Ash1l in regulating the differentiation of C3 cells is linked to its histone methyltransferase activity. Subcutaneous ex vivo transplantation experiments confirmed the role of Ash1l in the promotion of osteogenesis. Further experiments proved that Ash1l can epigenetically affect the expression of essential osteogenic and chondrogenic transcription factors. It exerts this impact via modifications in the enrichment of H3K4me3 on their promoter regions. Considering the promotional action of Ash1l on bone, it could potentially prompt new therapeutic strategy to promote osteogenesis. Stem Cells 2019;37:115-127.

Vascularization converts the lineage fate of bone mesenchymal stem cells to endothelial cells in tissue-engineered bone grafts by modulating FGF2-RhoA/ROCK signaling

The prevascularization of tissue-engineered bone grafts (TEBGs) has been shown to accelerate capillary vessel ingrowth in bone defect remodeling and to enhance new bone formation. However, the exact mechanisms behind this positive effect remain unknown. Here, we report that basic fibroblast growth factor (FGF2)-Ras homolog gene family member A (RhoA)/Rho-associated protein kinase (ROCK) signaling functions as a molecular switch to regulate the lineage fate of bone mesenchymal stem cells (BMSCs) and that prevascularization promotes the cell fate switch, which contributes to increased bone regeneration with the use of prevascularized TEBGs compared with control TEBGs. Prevascularized TEBGs enhanced the in vivo endothelial differentiation of BMSCs by inhibiting RhoA/ROCK signaling. In vitro data more clearly showed that BMSCs differentiated into von Willebrand factor (vWF)-positive endothelial cells, and FGF2-induced inhibition of RhoA/ROCK signaling played a key role. Our novel findings uncovered a new mechanism that stimulates the increased vascularization of engineered bone and enhanced regeneration by promoting the endothelial differentiation of BMSCs implanted in TEBGs. These results offer a new molecular target to regulate TEBG-induced bone regeneration.

Ras homolog family member A/Rho-associated protein kinase 1 signaling modulates lineage commitment of mesenchymal stem cells in asthmatic patients through lymphoid enhancer–binding factor 1

Numbers of mesenchymal stem cells (MSCs) are increased in the airways after allergen challenge. Ras homolog family member A(RhoA)/Rho-associated protein kinase 1 (ROCK) signaling is critical in determining the lineage fate of MSCs in tissue repair/remodeling. We sought to investigate the role of RhoA/ROCK signaling in lineage commitment of MSCs during allergen-induced airway remodeling and delineate the underlying mechanisms. Active RhoA expression in lung tissues of asthmatic patients and its role in cockroach allergen-induced airway inflammation and remodeling were investigated. RhoA/ROCK signaling-mediated MSC lineage commitment was assessed in an asthma mouse model by using MSC lineage tracing mice (nestin-Cre; ROSA26-EYFP). The role of RhoA/ROCK in MSC lineage commitment was also examined by using MSCs expressing constitutively active RhoA (RhoA-L63) or dominant negative RhoA (RhoA-N19). Downstream RhoA-regulated genes were identified by using the Stem Cell Signaling Array. Lung tissues from asthmatic mice showed increased expression of active RhoA when compared with those from control mice. Inhibition of RhoA/ROCK signaling with fasudil, a RhoA/ROCK inhibitor, reversed established cockroach allergen-induced airway inflammation and remodeling, as assessed based on greater collagen deposition/fibrosis. Furthermore, fasudil inhibited MSC differentiation into fibroblasts/myofibroblasts but promoted MSC differentiation into epithelial cells in asthmatic nestin-Cre; ROSA26-EYFP mice. Consistently, expression of RhoA-L63 facilitated differentiation of MSCs into fibroblasts/myofibroblasts, whereas expression of RhoA-19 switched the differentiation toward epithelial cells. The gene array identified the Wnt signaling effector lymphoid enhancer-binding factor 1 (Lef1) as the most upregulated gene in RhoA-L63-transfected MSCs. Knockdown of Lef1 induced MSC differentiation away from fibroblasts/myofibroblasts but toward epithelial cells. These findings uncover a previously unrecognized role of RhoA/ROCK signaling in MSC-involved airway repair/remodeling in the setting of asthma.

SiNWs Biophysically Regulate the Fates of Human Mesenchymal Stem Cells

While biophysical stimuli from polymeric matrices are known to significantly affect the fates of human mesenchymal stem cells (hMSCs), the stimulatory effects of nano-sized silicon-based matrices on hMSCs have not been thoroughly investigated. We previously demonstrated that vertically aligned, single-crystalline silicon nanowires (SiNWs) can control the osteogenicity of hMSCs via controllable spring constants from SiNWs matrix. However, other possible differentiation fates of hMSCs on SiNWs have not been explored. We hypothesize that tunable spring constant from artificial SiNWs matrices can direct different types of hMSC differentiations. The spring constants of tunable SiNW matrices can be consistently controlled by tuning the SiNW length. The results of gene expression and cell stiffness suggest that hMSCs differentiations are sensitive to our distinguishable spring constants from the SiNWs groups, and simultaneously conduct osteogenicity and adipogenicity. These findings suggest that SiNW matrices can regulate the fates of hMSCs when the SiNW characteristics are carefully tuned.

Histone demethylase JMJD6 regulates cellular migration and proliferation in adipose-derived mesenchymal stem cells

BackgroundAdipose-derived mesenchymal stem cells (ADSCs) have been extensively explored as a promising therapeutic agent due to their differentiation, proliferation and migration abilities. The epigenetic mechanisms that regulate the fate of mesenchymal stem cells (MSCs) have been described in detail. However, the epigenetic modulation of ADSCs proliferation and migration is poorly understood.MethodsThe present study examined histone demethylases roles and expression by RT-PCR, as well as through siRNA screening and ChIP-qPCR assay. Cellular proliferation and migration assays were employed in shRNA-mediated JMJD6 knockdown and control ADSCs. PDE1C inhibition studies were conducted to confirm its role in JMJD6-mediated epigenetic regulation of ADSCs.ResultsThe data demonstrate that the histone demethylase JMJD6 plays a critical role in regulating the proliferation and migration of ADSCs by removing H4R3me2a at the promoter regions of PDEC1 and suppressing PDEC1 expression. Importantly, the depletion of JMJD6 in ADSCs significantly increased cellular proliferation and motility, which was associated with increases in PDE1C expression and decreases in the levels of both cAMP and cGMP. The increase in proliferation and migration was reversed by treatment with a PDE1C inhibitor, suggesting that JMJD6 attenuates the proliferation and migration of ADSCs as an epigenetic regulator and PDE1C partially contributes to the JMJD6-mediated regulation.ConclusionsTaken together, our results indicate for the first time that JMJD6 plays an important role in the regulation of ADSCs proliferation and migration through the modulation of PDE1C expression.

How to influence the mesenchymal stem cells fate? Emerging role of ectoenzymes metabolizing nucleotides.

Extracellular purines, principally adenosine triphosphate and adenosine, are among the oldest evolutionary and widespread chemical messengers. The integrative view of purinergic signaling as a multistage coordinated cascade involves the participation of nucleotides/nucleosides, their receptors, enzymes metabolizing extracellular nucleosides and nucleotides as well as several membrane transporters taking part in the release and/or uptake of these molecules. In view of the emerging data, it is evident and widely accepted that an extensive network of diverse enzymatic activities exists in the extracellular space. The enzymes regulate the availability of nucleotide and adenosine receptor agonists, and consequently, the course of signaling events. The current data indicate that mesenchymal stem cells (MSCs) and cells induced to differentiate exhibit different sensitivity to purinergic ligands as well as a distinct activity and expression profiles of ectonucleotidases than mature cells. In the proposed review, we postulate for a critical role of these enzymatic players which, by orchestrating a fine-tune regulation of nucleotides concentrations, are integrally involved in modulation and diversification of purinergic signals. This specific hallmark of the MSC purinome should be linked with cell-specific biological potential and capacity for tissue regeneration. We anticipate this publication to be a starting point for scientific discussion and novel approach to the in vitro and in vivo regulation of the MSC properties.

MiR‑330‑5p inhibits H2O2‑induced adipogenic differentiation of MSCs by regulating RXRγ.

The elucidation of the underlying molecular mechanism of H2O2-induced adipocyte differentiation in mesenchymal stem cells (MSCs) is important for the development of treatments for metabolic diseases. The aim of the present study was to identify microRNA (miR)-330-5p, which targets retinoid X receptor γ (RXRγ) and to determine the function of H2O2-induced adipogenic differentiation of MSCs. During differentiation of MSCs into adipocytes induced by H2O2, miR-330-5p expression was decreased with a concomitant increase in RXRγ expression. A luciferase assay with RXRγ 3′-untranslated region (UTR) reporter plasmid, including the miR-330-5p-binding sequences, identified that the introduction of miR-330-5p decreases luciferase activity. However, it did not affect the activity of mutated RXRγ 3′-UTR reporter. Enforced expression of miR-330-5p significantly inhibited adipocyte differentiation by decreasing RXRγ mRNA and protein levels. In contrast, inhibition of the endogenous miR-330-5p promoted the formation of lipid droplets by rescuing RXRγ expression. Furthermore, the effects of inhibition of RXRγ were similar to those of overexpression of miR-330-5p on H2O2-induced adipogenic differentiation from MSCs. miR-330-5p inhibits H2O2-induced adipogenic differentiation of MSCs, and this is dependent on RXRγ. Taken together, the results of the present study revealed that miR-330-5p acts as a critical regulator of RXRγ, and is able to determinate the fate of MSCs to differentiate into adipocytes. This suggests that miR-330-5p and RXRγ may be target molecules for controlling metabolic diseases.

Notch-inducing hydrogels reveal a perivascular switch of mesenchymal stem cell fate.

The fate of mesenchymal stem cells (MSCs) in the perivascular niche, as well as factors controlling their fate, is poorly understood. Here, we study MSCs in the perivascular microenvironment of endothelial capillaries by modifying a synthetic 3D biomimetic poly(ethylene glycol) (PEG)-hydrogel system in vitro We show that MSCs together with endothelial cells form micro-capillary networks specifically in soft PEG hydrogels. Transcriptome analysis of human MSCs isolated from engineered capillaries shows a prominent switch in extracellular matrix (ECM) production. We demonstrate that the ECM phenotypic switch of MSCs can be recapitulated in the absence of endothelial cells by functionalizing PEG hydrogels with the Notch-activator Jagged1. Moreover, transient culture of MSCs in Notch-inducing microenvironments reveals the reversibility of this ECM switch. These findings provide insight into the perivascular commitment of MSCs by use of engineered niche-mimicking synthetic hydrogels.

Differentiation Potential of Mesenchymal Stem Cells and Stimulation of Nerve Regeneration

Mesenchymal stem cells (MSCs) are widely used in experimental research on cell therapy intended for the stimulation of repair processes in damaged tissues and organs. The present review summarizes the results of studies devoted to the possible directions of MSC differentiation after the transplantation of these cells into damaged nerves or special engineered structures of biological and artificial biodegradable materials that join the ends of a damaged nerve (nerve conduits). Data on exogenous MSC differentiation into Schwann cells, pericytes, smooth muscle cells, endotheliocytes, and other cell types are presented. Methods for preliminary MSC differentiation in vitro and examples of beneficial effects of these cells transplanted into damaged conductive nerves on nerve regeneration are given. The fate of exogenous MSCs placed into an unnatural biological niche remains poorly characterized and requires further studies, as emphasized in the review.

Control of MSC Differentiation by Tuning the Alkyl Chain Length of Phenylboroinc Acid Based Low-molecular-weight Gelators

The physical environment plays a critical role in modulating stem cell differentiation into specific lineages. In this study, we designed and synthesized a series of low-molecular-weight gels (LMWGs) with different moduli based on phenylboronic acid derivatives. The moduli of the LMWGs were readily tuned by varying the alkyl chain without any chemical crosslinker. The cell responses to the gels were evaluated with mesenchymal stem cell (MSCs), in respect of cell morphology, proliferation and differentiation. The prepared gels were non-toxic to MSCs, suggesting good biocompatibility. The hydrogel stiffness exerted a striking modulation effect on MSC fate decisions, where MSCs were inclined to differentiate into osteoblasts in stiff LMWGs and into chondrocytes in soft LMWGs. The pivotal elastic modulus of the LMWGs to drive MSC differentiation into osteoblastic lineage and chondrocytic lineage were approximately 20 kPa – 40 kPa and 1 kPa – 10 kPa, respectively. Overall, our results demonstrated that the modification of hydrogel stiffness via tuning the alkyl chain was a simple but effective approach to regulate MSC differentiation into specific lineage, which might have important implications in the design of LMWGs for tissue engineering applications.

The Fate of Endometrial Mesenchymal Stem Cells After Application in the Healthy Equine Uterus

In vivo local antitumor activity of fibrin gels (FBGs) loaded with the poly-cyclodextrin oCD-NH2/Dox, compared to free Dox, was evaluated in two mouse orthotopic neuroblastoma (NB) models, after positioning of the releasing devices in the visceral space. FBGs were prepared at the fibrinogen (FG) concentrations of 22 and 40 mg/ml clotted in the presence of 0.81 mM/mg FG Ca2+ and 1.32 U/mg FG thrombin.Our results indicate that FBGs loaded with oCD-NH2/Dox and applied as neoadjuvant loco-regional treatment, show an antitumor activity significantly greater than that displayed by the same FBGs loaded with identical dose of Dox or after free Dox administered intra venous (iv). In particular, FBGs prepared at 40 mg/ml showed a slightly lower antitumor activity, although after their positioning we observed a significant initial reduction of tumor burden lasting for several days after gel implantation.FBGs at 22 mg/ml loaded with oCD-NH2/Dox and applied after tumor removal (adjuvant treatment model) showed a significantly better antitumor activity than the iv administration of free Dox, with 90% tumor regrowth reduction compared to untreated controls.In all cases the weight loss post-treatment was limited after gel application, although in the adjuvant treatment the loss of body weight lasted longer than in the other treatment modality.In accordance with our recent published data on the low local toxic effects of FBGs, the present findings also underline an increase of the therapeutic index of Dox when locally administered through FBGs loaded with the oCD-NH2/Dox complex.

Extracellular matrix protein DMP1 suppresses osteogenic differentiation of Mesenchymal Stem Cells

Mesenchymal Stem Cells (MSCs) are self-renewing and multipotent stem cells which was investigated for diverse clinical applications. However, complex mechanism of MSCs fate determination is still not fully disclosed. Extracellular matrix (ECM) proteins contribute to maintain MSCs stemness by providing extracellular microenvironment. Increasing evidences show that ECM proteins could also regulate the fate of MSCs directly. Dentin matrix protein 1 (DMP1) is an ECM protein enrich in bone tissue and terminal cells, which well-known in promoting osteoblasts and osteocytes maturation, and facilitate mineralization. Recently, our experiment indicated that DMP1 was also expressed in MSCs of long bone. In present study, it is found that DMP1 expressed in Prx1 positive MSCs. And, DMP1 is down-regulated in early osteoblasts and up-regulated again in mature osteoblasts. DMP1 conditional knockout mice model under Prx1cre was generated to explore whether DMP1 regulates MSCs osteogenic differentiation. Specific ablation of DMP1 in Prx1 positive MSCs increased bone mass in vivo and promoted osteoblasts activity in vitro. This study provides a new understanding of DMP1's function in regulation of osteogenesis: not only an enhancer of bone formation, but also a negative regulator of MSCs differentiation in bone.

Mechanotransduction: Kindlin' the fate of mesenchymal stem cells.

Kindlin-2 controls mesenchymal stem cell differentiation in response to matrix stiffness by regulating the levels and activity of YAP and TAZ.

Role of Marrow Adipocytes in Regulation of Energy Metabolism and Bone Homeostasis.

The goal of this review is to gain a better understanding of marrow adipocyte development, its regulation of energy, and its characterization responsible for bone homeostasis. Despite major advances in uncovering the complex association of bone-fat in the marrow, the underlying basic biological process of adipose tissue development, as well as its interaction with bone homeostasis in pathophysiological conditions, is still not well understood. This review identifies many pro- and anti-osteogenic factors secreted by adipocytes to play a role in the manipulating the fate of mesenchymal stem cells as well as the osteoblastic activity during bone remodeling. It also addresses the function of adipose tissue capable of negative regulation of the hematopoietic microenvironment to influence the bone quantity and the nature of bone homeostasis.

Kindlin-2 regulates mesenchymal stem cell differentiation through control of YAP1/TAZ.

Precise control of mesenchymal stem cell (MSC) differentiation is critical for tissue development and regeneration. We show here that kindlin-2 is a key determinant of MSC fate decision. Depletion of kindlin-2 in MSCs is sufficient to induce adipogenesis and inhibit osteogenesis in vitro and in vivo. Mechanistically, kindlin-2 regulates MSC differentiation through controlling YAP1/TAZ at both the transcript and protein levels. Kindlin-2 physically associates with myosin light-chain kinase in response to mechanical cues of cell microenvironment and intracellular signaling events and promotes myosin light-chain phosphorylation. Loss of kindlin-2 inhibits RhoA activation and reduces myosin light-chain phosphorylation, stress fiber formation, and focal adhesion assembly, resulting in increased Ser127 phosphorylation, nuclear exclusion, and ubiquitin ligase atrophin-1 interacting protein 4-mediated degradation of YAP1/TAZ. Our findings reveal a novel kindlin-2 signaling axis that senses the mechanical cues of cell microenvironment and controls MSC fate decision, and they suggest a new strategy to regulate MSC differentiation, tissue repair, and regeneration.