RPLP0/TBP are the most stable reference genes for human dental pulp stem cells under osteogenic differentiation

BACKGROUND Validation of the reference gene(RG)stability during experimental analyses is essential for correct quantitative real-time polymerase chain reaction(RT-qPCR)data normalisation.Commonly,in an unreliable way,several studies use genes involved in essential cellular functions[glyceraldehyde-3-phosphate dehydro-genase(GAPDH),18S rRNA,andβ-actin]without paying attention to whether they are suitable for such experimental conditions or the reason for choosing such genes.Furthermore,such studies use only one gene when Minimum Information for Publication of Quantitative Real-Time PCR Experiments guidelines recom-mend two or more genes.It impacts the credibility of these studies and causes dis-tortions in the gene expression findings.For tissue engineering,the accuracy of gene expression drives the best experimental or therapeutical approaches.We cultivated DPSCs under two conditions:Undifferentiated and osteogenic dif-ferentiation,both for 35 d.We evaluated the gene expression of 10 candidates for RGs[ribosomal protein,large,P0(RPLP0),TATA-binding protein(TBP),GAPDH,actin beta(ACTB),tubulin(TUB),aminolevulinic acid synthase 1(ALAS1),tyro-sine 3-monooxygenase/tryptophan 5-monooxygenase activation protein,zeta(YWHAZ),eukaryotic translational elongation factor 1 alpha(EF1a),succinate dehydrogenase complex,subunit A,flavoprotein(SDHA),and beta-2-micro-globulin(B2M)]every 7 d(1,7,14,21,28,and 35 d)by RT-qPCR.The data were analysed by the four main algorithms,ΔCt method,geNorm,NormFinder,and BestKeeper and ranked by the RefFinder method.We subdivided the samples into eight subgroups.RESULTS All of the data sets from clonogenic and osteogenic samples were analysed using the RefFinder algorithm.The final ranking showed RPLP0/TBP as the two most stable RGs and TUB/B2M as the two least stable RGs.Either theΔCt method or NormFinder analysis showed TBP/RPLP0 as the two most stable genes.However,geNorm analysis showed RPLP0/EF1αin the first place.These algorithms’two least stable RGs were B2M/GAPDH.For BestKeeper,ALAS1 was ranked as the most stable RG,and SDHA as the least stable RG.The pair RPLP0/TBP was detected in most subgroups as the most stable RGs,following the RefFinfer ranking.CONCLUSION For the first time,we show that RPLP0/TBP are the most stable RGs,whereas TUB/B2M are unstable RGs for long-term osteogenic differentiation of human DPSCs in traditional monolayers.

O-linkedβ-N-acetylglucosaminylation may be a key regulatory factor in promoting osteogenic differentiation of bone marrow mesenchymal stromal cells

Cumulative evidence suggests that O-linkedβ-N-acetylglucosaminylation(OGlcNAcylation)plays an important regulatory role in pathophysiological processes.Although the regulatory mechanisms of O-GlcNAcylation in tumors have been gradually elucidated,the potential mechanisms of O-GlcNAcylation in bone metabolism,particularly,in the osteogenic differentiation of bone marrow mesenchymal stromal cells(BMSCs)remains unexplored.In this study,the literature related to O-GlcNAcylation and BMSC osteogenic differentiation was reviewed,assuming that it could trigger more scholars to focus on research related to OGlcNAcylation and bone metabolism and provide insights into the development of novel therapeutic targets for bone metabolism disorders such as osteoporosis.

Exercise promotes osteogenic differentiation by activating the long non-coding RNA H19/microRNA-149 axis

BACKGROUND Regular physical activity during childhood and adolescence is beneficial to bone development,as evidenced by the ability to increase bone density and peak bone mass by promoting bone formation.AIM To investigate the effects of exercise on bone formation in growing mice and to investigate the underlying mechanisms.METHODS 20 growing mice were randomly divided into two groups:Con group(control group,n=10)and Ex group(treadmill exercise group,n=10).Hematoxylin-eosin staining,immunohistochemistry,and micro-CT scanning were used to assess the bone formation-related indexes of the mouse femur.Bioinformatics analysis was used to find potential miRNAs targets of long non-coding RNA H19(lncRNA H19).RT-qPCR and Western Blot were used to confirm potential miRNA target genes of lncRNA H19 and the role of lncRNA H19 in promoting osteogenic differentiation.RESULTS Compared with the Con group,the expression of bone morphogenetic protein 2 was also significantly increased.The micro-CT results showed that 8 wk moderate-intensity treadmill exercise significantly increased bone mineral density,bone volume fraction,and the number of trabeculae,and decreased trabecular segregation in the femur of mice.Inhibition of lncRNA H19 significantly upregulated the expression of miR-149 and suppressed the expression of markers of osteogenic differentiation.In addition,knockdown of lncRNA H19 significantly downregulated the expression of autophagy markers,which is consistent with the results of autophagy-related protein changes detected in mouse femurs by immunofluorescence.CONCLUSION Appropriate treadmill exercise can effectively stimulate bone formation and promote the increase of bone density and bone volume in growing mice,thus enhancing the peak bone mass of mice.The lncRNA H19/miR-149 axis plays an important regulatory role in osteogenic differentiation.

Adipokines regulate mesenchymal stem cell osteogenic differentiation

Mesenchymal stem cells(MSCs)can differentiate into various tissue cell types including bone,adipose,cartilage,and muscle.Among those,osteogenic differentiation of MSCs has been widely explored in many bone tissue engineering studies.Moreover,the conditions and methods of inducing osteogenic differentiation of MSCs are continuously advancing.Recently,with the gra-dual recognition of adipokines,the research on their involvement in different pathophysiological processes of the body is also deepening including lipid metabolism,inflammation,immune regulation,energy disorders,and bone homeostasis.At the same time,the role of adipokines in the osteogenic differentiation of MSCs has been gradually described more completely.Therefore,this paper reviewed the evidence of the role of adipokines in the osteogenic differentiation of MSCs,emphasizing bone formation and bone regeneration.

A novel mutation in ROR2 led to the loss of function of ROR2 and inhibited the osteogenic differentiation capability of bone marrow mesenchymal stem cells(BMSCs)

Receptor tyrosine kinase-like orphan receptor 2(ROR2)has a vital role in osteogenesis.However,the mechanism underlying the regulation of ROR2 in osteogenic differentiation is still poorly comprehended.A previous study by our research group showed that a novel compound heterozygous ROR2 variation accounted for the autosomal recessive Robinow syndrome(ARRS).This study attempted to explore the impact of the ROR2:c.904C>T variant specifically on the osteogenic differentiation of BMSCs.Methods:Coimmunoprecipitation(CoIP)-western blotting was carried out to identify the interaction between ROR2 and Wnt5a.Double-immunofluorescence staining was used for determining the expressions and co-localization of ROR2 and Wnt5a in bone marrow mesenchymal stem cells(BMSCs).Western blot(WB)analysis and quantitative reverse transcription polymerase chain reaction(RT-qPCR)were conducted to identify the expression levels of ROR2 in the BMSCs transfected with LV-shROR2 or LV-ROR2-c.904C>T.The alkaline phosphatase(ALP)activity was detected,and Alizarin Red S staining was done for evaluating the osteogenic differentiation of BMSCs.RT-qPCR was employed to identify the expression of the sphingomyelin synthase 1(SMS1)mRNA in the BMSCs transfected with LV-shROR2 or LV-ROR2-c.904C>T and the mRNA expression levels of Runt-related transcription factor 2(RUNX2),osteocalcin(OCN),and osteopontin(OPN).WB was performed to confirm the protein expressions of extracellular regulated protein kinases1(ERK),P-ERK,Smad family member1/5/8(Smad1/5/8),P-Smad1/5/8,P-P38,P38,RUNX2,OCN,and OPN in the BMSCs transfected with LV-shROR2/LV-ROR2-c.904C>T and sphingomyelin(SM).Results:The ROR2:c.904C>T mutant altered the subcellular localization of the ROR2 protein,which caused an impaired interaction between ROR2 and Wnt5a.The depletion of ROR2 restricted the osteogenic differentiation capability of BMSCs and downregulated the expression of SMS1.SM treatment could reverse the inhibition of osteoblastic differentiation in ROR2-depleted BMSCs.Conclusion:The findings of this work revealed that the ROR2:c.904C>T variant led to the loss of function of ROR2,which impaired the interaction between ROR2 and Wnt5a and also controlled the osteogenic differentiation capability of BMSCs.Furthermore,SM was revealed to be engaged in the osteoblastic differentiation of BMSCs regulated by ROR2,which renders SM a potential target in the therapy for ARRS.

MicroRNA-584-5p/RUNX family transcription factor 2 axis mediates hypoxia-induced osteogenic differentiation of periosteal stem cells

BACKGROUND The hypoxic environment during bone healing is important in regulating the differentiation of periosteal stem cells(PSCs)into osteoblasts or chondrocytes;however,the underlying mechanisms remain unclear.AIM To determine the effect of hypoxia on PSCs,and the expression of microRNA-584-5p(miR-584-5p)and RUNX family transcription factor 2(RUNX2)in PSCs was modulated to explore the impact of the miR-584-5p/RUNX2 axis on hypoxiainduced osteogenic differentiation of PSCs.METHODS In this study,we isolated primary mouse PSCs and stimulated them with hypoxia,and the characteristics and functional genes related to PSC osteogenic differentiation were assessed.Constructs expressing miR-584-5p and RUNX2 were established to determine PSC osteogenic differentiation.RESULTS Hypoxic stimulation induced PSC osteogenic differentiation and significantly increased calcified nodules,intracellular calcium ion levels,and alkaline phosphatase(ALP)activity in PSCs.Osteogenic differentiation-related factors such as RUNX2,bone morphogenetic protein 2,hypoxia-inducible factor 1-alpha,and ALP were upregulated;in contrast,miR-584-5p was downregulated in these cells.Furthermore,upregulation of miR-584-5p significantly inhibited RUNX2 expression and hypoxia-induced PSC osteogenic differentiation.RUNX2 was the target gene of miR-584-5p,antagonizing miR-584-5p inhibition in hypoxia-induced PSC osteogenic differentiation.CONCLUSION Our study showed that the interaction of miR-584-5p and RUNX2 could mediate PSC osteogenic differentiation induced by hypoxia.

DNA N^6-methyladenine demethylase ALKBH1 enhances osteogenic differentiation of human MSCs

ALKBH1 was recently discovered as a demethylase for DNA N6-methyladenine （N6-mA）, a new epigenetic modification, and interacts with the core transcriptional pluripotency network of embryonic stem cells. However, the role of ALKBH1 and DNA N6-mA in regulating osteogenic differentiation is largely unknown. In this study, we demonstrated that the expression of ALKBH1 in human mesenchymal stem cells （MSCs） was upregulated during osteogenic induction. Knockdown of ALKBH1 increased the genomic DNA N6-mA levels and significantly reduced the expression of osteogenic-related genes, alkaline phosphatase activity, and mineralization. ALKBHl-depleted MSCs also exhibited a restricted capacity for bone formation in vivo. By contrast, the ectopic overexpression of ALKBH1 enhanced osteoblastic differentiation. Mechanically, we found that the depletion of ALKBH1 resulted in the accumulation of N6-mA on the promoter region of ATF4, which subsequently silenced ATF4 transcription. In addition, restoring the expression of ATP by adenovirus-mediated transduction successfully rescued osteogenic differentiation. Taken together, our results demonstrate that ALKBH1 is indispensable for the osteogenic differentiation of MSCs and indicate that DNA N6-mA modifications area new mechanism for the epigenetic regulation of stem cell differentiation.

AFF1 and AFF4 differentially regulate the osteogenic differentiation of human MSCs

AFF1 and AFF4 belong to the AFF （AF4/FMR2） family of proteins, which function as scaffolding proteins linking two different transcription elongation factors, positive elongation factor b （P-TEFb） and ELL1/2, in super elongation complexes （SECs）. Both AFF1 and AFF4 regulate gene transcription through elongation and chromatln remodeling. However, their function in the osteogenic differentiation of mesenchymal stem cells （MSCs） is unknown. In this study, we show that small interfering RNA （siRNA）-mediated depletion of AFF1 in human MSCs leads to increased alkaline phosphatase （ALP） activity, enhanced mineralization and upregulated expression of osteogenic-related genes. On the contrary, depletion of AFF4 significantly inhibits the osteogenic potential of MSCs. In addition, we confirm that overexpression of AFF1 and AFF4 differentially affects osteogenic differentiation in vitro and MSC-mediated bone formation in vivo. Mechanistically, we find that AFFI regulates the expression of DKK1 via binding to its promoter region. Depletion of DKK1 in HA-AFFl-overexpressing MSCs abrogates the impairment of osteogenic differentiation. Moreover, we detect that AFF4 is enriched in the promoter region of ID1. AFF4 knockdown blunts the BRE luciferase activity, SP7 expression and ALP activity induced by BMP2 treatment. In conclusion, our data indicate that AFF1 and AFF4 differentially regulate the osteogenic differentiation of human MSCs.AFF1 and AFF4 belong to the AFF （AF4/FMR2） family of proteins, which function as scaffolding proteins linking two different transcription elongation factors, positive elongation factor b （P-TEFb） and ELL1/2, in super elongation complexes （SECs）. Both AFFI and AFF4 regulate gene transcription through elongation and chromatln remodeling. However, their function in the osteogenic differentiation of mesenchymal stem cells （MSCs） is unknown. In this study, we show that small interfering RNA （siRNA）-mediated depletion of AFF1 in human MSCs leads to increased alkaline phosphatase （ALP） activity, enhanced mineralization and upregulated expression of osteogenic-related genes. On the contrary, depletion of AFF4 significantly inhibits the osteogenic potential of MSCs. In addition, we confirm that overexpression of AFF1 and AFF4 differentially affects osteogenic differentiation in vitro and MSC-mediated bone formation in vivo. Mechanistically, we find that AFFI regulates the expression of DKK1 via binding to its promoter region. Depletion of DKK1 in HA-AFFl-overexpressing MSCs abrogates the impairment of osteogenic differentiation. Moreover, we detect that AFF4 is enriched in the promoter region of ID1. AFF4 knockdown blunts the BRE luciferase activity, SP7 expression and ALP activity induced by BMP2 treatment. In conclusion, our data indicate that AFF1 and AFF4 differentially regulate the osteogenic differentiation of human MSCs.

Low-power laser irradiation promotes the proliferation and osteogenic differentiation of human periodontal ligament cells via cyclic adenosine monophosphate

Retaining or improving periodontal ligament （PDL） function is crucial for restoring periodontal defects. The aim of this study was to evaluate the physiological effects of low-power laser irradiation （LPLI） on the proliferation and osteogenic differentiation of human PDL （hPDL） cells. Cultured hPDL cel Is were irradiated （660 nm） daily with doses of O, 1, 2 or 4 J .cm-2. Cell proliferation was evaluated by the 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide （MTT） assay, and the effect of LPLI on osteogenic differentiation was assessed by Alizarin Red S staining and alkaline phosphatase （ALP） activity. Additionally, osteogenic marker gene expression was confirmed by real-time reverse transcription-polymerase chain reaction （RT-PCR）. Our data showed that LPLI at a dose of 2 J.cm-2 significantly promoted hPDL cell proliferation at days 3 and 5. In addition, LPLI at energy doses of 2 and 4 J.cm-2 showed potential osteogenic capacity, as it stimulated ALP activity, calcium deposition, and osteogenic gene expression. We also showed that cyclic adenosine monophosphate （cAMP） is a critical regulator of the LPLI-mediated effects on hPDL cells. This study shows that LPLI can promote the proliferation and osteogenic differentiation of hPDL cells. These results suggest the potential use of LPLI in clinical applications for periodontal tissue regeneration.

TGF-beta 1 Gene-Activated Matrices Regulated the Osteogenic Differentiation of BMSCs

Poly （lactic acid/glycolic acid/asparagic acid-co-polyethylene glycol）（PLGA-[ASP-PEG]） scaffold materials were linked with a novel nonviral vector （K）16GRGDSPC through cross linker Sulfo- LC-SPDP to construct a new type of nonviral gene transfer system. Eukaryotic expressing vector containing transforming growth factor beta 1 （pcDNA3-TGFβ1） was encapsulated by the system. Bone marrow stromal cells （BMSCs） obtained from rabbit were cultured on PLGA-[ASP-PEG] modified by （K）16GRGDSPC and TGF-β1 gene and PLGA-[ASP-PEG] modified by （K）16GRGDSPC and empty vector pcDNA3 as control. The expressions of osteogenic makers of the BMSCs cultured on the TGF-β1 gene-activated scaffold materials were found significantly higher than those of the control group （P〈0.05）. A brand-new way was provided for regulating seed cells to directionally differentiate into osteoblasts for bone defect restoration in bone tissue engineering.

circ_0003204 regulates the osteogenic differentiation of human adipose-derived stem cells via miR-370-3p/HDAC4 axis

Human adipose-derived stem cells(hASCs)are a promising cell type for bone tissue regeneration.Circular RNAs(circRNAs)have been shown to play a critical role in regulating various cell differentiation and involve in mesenchymal stem cell osteogenesis.However,how circRNAs regulate hASCs in osteogenesis is still unclear.Herein,we found circ_0003204 was significantly downregulated during osteogenic differentiation of hASCs.Knockdown of circ_0003204 by si RNA or overexpression by lentivirus confirmed circ_0003204 could negatively regulate the osteogenic differentiation of hASCs.We performed dual-luciferase reporting assay and rescue experiments to verify circ_0003204 regulated osteogenic differentiation via sponging miR-370-3p.We predicted and confirmed that miR-370-3p had targets in the 3′-UTR of HDAC4 m RNA.The following rescue experiments indicated that circ_0003204 regulated the osteogenic differentiation of hASCs via miR-370-3p/HDAC4 axis.Subsequent in vivo experiments showed the silencing of circ_0003204 increased the bone formation and promoted the expression of osteogenic-related proteins in a mouse bone defect model,while overexpression of circ_0003204 inhibited bone defect repair.Our findings indicated that circ_0003204 might be a promising target to promote the efficacy of hASCs in repairing bone defects.

Poly(dopamine)-assisted Bioactive Coating on the Surface of Porous Poly (Ether Ether Ketone) to Promote Osteogenic Differentiation of rBMSC

A facile modification strategy is developed to promote the proliferation and osteogenic differentiation of rat bone marrow stromal cells(rBMSCs)through deposition of a bioactive calcium silicate(CS)coating on the porous surface of poly(ether-ether-ketone)(PEEK)with the assistance of poly(dopamine)(PDA).The porous structures are etched on the surface of PEEK after sulfonation treatment.A poly(dopamine)layer is coated on the porous surface of the sulfonated PEEK(SPEEK),which provides anchoring groups for the subsequent deposition of the CS layer.Results show that the CS coating on the porous surface of SPEEK significantly improve the hydrophilicity and biomineralization formation of hydroxyapatite.Compared with PEEK,SPEEK-PDA-CS displays higher bioactivity to promote the proliferation and osteogenic differentiation of rBMSCs,including the increase of ALP activity and formation of calcium nodules,the expression of osteogenic differentiation-related genes.These results are beneficial to extending clinical applications of PEEK-based implants for bone tissue repair and orthopedic surgery.

Cyclic biaxial tensile strain enhances osteogenic differentiation in rat bone marrow-derived mesenchymal stem cells via activating ERα-Wnt3a/β-catenin pathway

The present study was designed to investigate the role of estrogen receptorα(ERα)in biaxial tensile strain(BTS)regulated osteogenic differentiation of rat bone marrow-derived mesenchymal stem cells(rBMSCs).rBMSCs were derived fromrats and overexpressed ERα.The rBMSCs were subjected to BTS at 1Hz with a strain of 2%for 4 h per day,3 days,with or without ERαinhibitor ICI 182,780(ICI).Then,bone mineralization was performed by Alizarin Red Staining.The markers of osteogenic differentiation and downstream Wnt3a/β-catenin signaling were detected by western blotting.Results showed that BTS enhanced the osteogenic differentiation of rBMSCs,increased protein expression levels of alkaline phosphatase(ALP),runt-related transcription factor 2(Runx2),collagen type I(Col I)and osteocalcin(OCN),and it increased the protein expression levels of estrogen receptor(ER)α(ERα),Wnt3a,andβ-catenin.BTS The activated Wnt3a/β-catenin signaling pathway induced by BTS was abolished by ICI 182,780(ICI).In addition,overexpressing ERαin rBMSCs promoted the osteogenic differentiation by BTS.Taken together,BTS induced osteogenic differentiation of rBMSCs via the ERαand downstream canonical Wnt3a/β-catenin pathway.

Glucosamine increases the expression of YKL-40 and osteogenic marker genes in hMSC during osteogenic differentiation

Human mesenchymal stem cells(hMSC)can be expanded in vitro and differentiated towards osteogenic,chondrogenic or adipogenic lineages,making them an attractive source for tissue engineering and regenerative medicine.Chitinase-like-proteins(CLPs)belong to the family 18 glycosyl hydrolases and are believed to play a role in inflammation and tissue remodelling.The aim of this study was to determine the effect of the aminosugar glucosamine on the expression of the CLP YKL-40 during osteogenic differentiation of hMSC.Glucosamine did not affect multipotency of hMSC nor proliferation rate of undifferentiated hMSC.YKL-40 was expressed during both expansion of undifferentiated hMSC and during osteogenic differentiation.A slight but non-significant increase in YKL-40 expression was observed with glucosamine,accompanied by a pH-dependent delay in mineralization.However,glucosamine induced higher expression of osteogenic marker genes.

Controlling Osteogenic Differentiation through Nanoporous Alumina

Nanotopographical features are found to have significant effects on bone behavior. In the present study, nanoporous aluminas with different pore sizes (20, 100 and 200 nm in diameter), were evaluated for their osteoinductive and drug eluting properties. W20-17 marrow stromal cells were seeded on nanoporous alumina with and without the addition of BMP-2. Although cell proliferation was not affected by pore size, osteogenic differentiation was 200 nm as compared to 20 and 100 nm pores induced higher alkaline phosphatase activity (ALP) and osteocalcin expression levels, thus indicating osteoblastic differentiation. Cell morphology revealed that cells cultured on 20 nm pores adopted a rounded shape, while larger pores (200 nm) elicited an elongated morphology. Furthermore, ALP expression levels were consistently higher on BMP-2 loaded nanoporous alumina surfaces compared to unloaded surfaces, indicating that not only is nanoporous alumina osteoinductive, but also has the potential to be used as a drug eluting bone-implant coating.

Influence of bone morphogenetic proteins-2 and strontium chloride on the human umbilical cord mesenchymal stem cells proliferation and osteogenic differentiation

Objective To study the effects of combination of bone morphogenetic protein-2 (BMP-2) and strontium chloride on proliferation and osteogenic differentiation of human umbilical cord mesenchymal stem cells(hUCM-SCs)in vitro culture.

Rhizoma Drynariae-derived nanovesicles reverse osteoporosis by potentiating osteogenic differentiation of human bone marrow mesenchymal stem cells via targeting ERα signaling

Although various anti-osteoporosis drugs are available,the limitations of these therapies,including drug resistance and collateral responses,require the development of novel anti-osteoporosis agents.Rhizoma Drynariae displays a promising anti-osteoporosis effect,while the effective component and mechanism remain unclear.Here,we revealed the therapeutic potential of Rhizoma Drynariae-derived nanovesicles(RDNVs)for postmenopausal osteoporosis and demonstrated that RDNVs potentiated osteogenic differentiation of human bone marrow mesenchymal stem cells(hBMSCs)by targeting estrogen receptor-alpha(ERα).RDNVs,a natural product isolated from fresh Rhizoma Drynariae root juice by differential ultracentrifugation,exhibited potent bone tissue-targeting activity and anti-osteoporosis efficacy in an ovariectomized mouse model.RDNVs,effectively internalized by hBMSCs,enhanced proliferation and ERαexpression levels of hBMSC,and promoted osteogenic differentiation and bone formation.Mechanistically,via the ERαsignaling pathway,RDNVs facilitated mRNA and protein expression of bone morphogenetic protein 2 and runt-related transcription factor 2 in hBMSCs,which are involved in regulating osteogenic differentiation.Further analysis revealed that naringin,existing in RDNVs,was the active component targeting ERαin the osteogenic effect.Taken together,our study identified that naringin in RDNVs displays exciting bone tissue-targeting activity to reverse osteoporosis by promoting hBMSCs proliferation and osteogenic differentiation through estrogen-like effects.

BMP9 induces osteogenic differentiation through up-regulating LGR4 via the mTORC1/ Stat3 pathway in mesenchymal stem cells

Bone defects and non-union are prevalent in clinical orthopedy,and the outcomes of current treatments are often suboptimal.Bone tissue engineering offers a promising approach to treating these conditions effectively.Bone morphogenetic protein 9(BMP9)can commit mesenchymal stem cells to osteogenic lineage,and a knowledge of the underlying mechanisms may help advance the field of bone tissue engineering.Leucine-rich repeats con-taining G protein-coupled receptor 4(LGR4),a member of G protein-coupled receptors,is essential for modulating bone development.This study is aimed at investigating the impact of LGR4 on BMP9-induced osteogenesis in mesenchymal stem cells as well as the underlying mechanisms.Bone marrow stromal cells from BMp9-knockout mice exhibited diminished LGR4 expression,and exogenous LGR4 clearly restored the impaired osteogenic potency of the bone marrow stromal cells.Furthermore,LGR4 expression was increased by BMP9 in C3H10T1/2 cells.LGR4 augmented the benefits of BMP9-induced osteogenic markers and bone formation,whereas LGR4 inhibition restricted these effects.Meanwhile,the BMP9-induced li-pogenic markers were increased by LGR4 inhibition.The protein levels of Raptor and p-Stat3 were elevated by BMP9.Raptor knockdown or p-Stat3 suppression attenuated the osteoblastic markers and LGR4 expression brought on by BMP9.LGR4 significantly reversed the blocking ef-fect of Raptor knockdown or p-Stat3 suppression on the BMP9-induced osteoblastic markers.Raptor interacts with p-Stat3,and p-Stat3 activates the LGR4 promoter activity.In conclusion,LGR4 boosts BMP9 osteoblastic potency in mesenchymal stem cells,and BMP9 may up-regulate LGR4 via the mTORC1/Stat3 signal activation.

Crosstalk between Wnt and bone morphogenetic protein signaling during osteogenic differentiati

Mesenchymal stem cells(MSCs)originate from many sources,including the bone marrow and adipose tissue,and differentiate into various cell types,such as osteoblasts and adipocytes.Recent studies on MSCs have revealed that many transcription factors and signaling pathways control osteogenic development.Osteogenesis is the process by which new bones are formed;it also aids in bone remodeling.Wnt/β-catenin and bone morphogenetic protein(BMP)signaling pathways are involved in many cellular processes and considered to be essential for life.Wnt/β-catenin and BMPs are important for bone formation in mammalian development and various regulatory activities in the body.Recent studies have indicated that these two signaling pathways contribute to osteogenic differen-tiation.Active Wnt signaling pathway promotes osteogenesis by activating the downstream targets of the BMP signaling pathway.Here,we briefly review the molecular processes underlying the crosstalk between these two pathways and explain their participation in osteogenic differentiation,emphasizing the canonical pathways.This review also discusses the crosstalk mechanisms of Wnt/BMP signaling with Notch-and extracellular-regulated kinases in osteogenic differentiation and bone development.

Liquiritigenin promotes osteogenic differentiation and prevents bone loss via inducing auto-lysosomal degradation and inhibiting apoptosis

Osteoporosis(OP)is a debilitating skeletal abnormality involving bone remodeling and bone cell homeostasis characterized by decreased bone strength and high fracture risk.A novel therapeutic intervention for OP by manipulating cellular autophagy-apoptosis processes to promote skeletal homeostasis is presented.Protective effects of the naturally occurring plant extract Liquiritigenin(LG)were demonstrated in an ovariectomy(OvX)-OP mouse model and preosteoblast MC3T3-E1 cells.Micro-CT and histological staining assessments of skeletal phenotype were applied alongside detection of autophagy activity in osteocytes and MC3T3-E1 cells by transmission electron microscopy(TEM).The effects of LG on chloroquine(CQ)-and the apoptosis-inducing TS-treated osteogenic differentiations and status of lysosomes within MC3T3-E1 cells were analyzed by Neutral red,Alizarin red S and alkaline phosphatase(ALP)staining and Western blot assays.Treatment with LG prevented bone loss,increased osteogenic differentiation in vivo and in vitro,and inhibited osteoclast formation to some extent.TEM analyses revealed that LG can improve auto-lysosomal degradation within osteocytes from OVX mice and MC3T3-E1 cells.The abnormal status of lysosomes associated with CQ and TS treatments was notably alleviated by LG which also reduced levels of apoptosis-induced inhibition of osteogenic differentiation and averted abnormal osteogenic differentiation as a consequence of a blockage in autolysosome degradation.Overall,LG stimulates bone growth in Oovx mice through increased osteogenic differentiation and regulation of autophagyapoptosis mechanisms,presenting an auspicious natural therapy for Op.