TLE4 Is a Critical Mediator of Osteoblast and Runx2-Dependent Bone Development.
Ontology highlight
ABSTRACT:
SUBMITTER: Shin TH
PROVIDER: S-EPMC8377417 | biostudies-literature |
REPOSITORIES: biostudies-literature
Similar Datasets
Project description:How lineage specifiers are regulated during development is an outstanding question, and the molecular regulation of osteogenic factor RUNX2 remains to be fully understood. Here we report that the Mediator subunit MED23 cooperates with RUNX2 to regulate osteoblast differentiation and bone development. Med23 deletion in mesenchymal stem cells or osteoblast precursors results in multiple bone defects similar to those observed in Runx2(+/-) mice. In vitro, Med23-deficient progenitor cells are refractory to osteoblast differentiation, and Med23 deficiency reduces Runx2-target gene activity without changing Runx2 expression. Mechanistically, MED23 binds to RUNX2 and modulates its transcriptional activity. Moreover, Med23 deficiency in osteoprogenitor cells exacerbates the skeletal abnormalities observed in Runx2(+/-) mice. Collectively, our results establish a genetic and physical interaction between RUNX2 and MED23, suggesting that MED23 constitutes a molecular node in the regulatory network of anabolic bone formation and related diseases.
| S-EPMC4821994 | biostudies-literature
Project description:The coupling of osteoblasts and osteocytes by connexin43 (Cx43) gap junctions permits the sharing of second messengers that coordinate bone cell function and cortical bone acquisition. However, details of how Cx43 converts shared second messengers into signals that converge onto essential osteogenic processes are incomplete. Here, we use in vitro and in vivo methods to show that Cx43 and Runx2 functionally interact to regulate osteoblast gene expression and proliferation, ultimately affecting cortical bone properties. Using compound hemizygous mice for the Gja1 (Cx43) and Runx2 genes, we observed a skeletal phenotype not visible in wild-type or singly hemizygous animals. Cortical bone analysis by micro-computed tomography (?CT) revealed that 8-week-old male, compound Gja1+/- Runx2+/- mice have a marked increase in cross-sectional area, endosteal and periosteal bone perimeter, and an increase in porosity compared to controls. These compound Gja1+/- Runx2+/- mice closely approximate the cortical bone phenotypes seen in osteoblast-specific Gja1-conditional knockout models. Furthermore, ?CT analysis of skulls revealed an altered interparietal bone geometry in compound hemizygotes. Consistent with this finding, Alizarin red/Alcian blue staining of 2-day-old Gja1+/- Runx2+/- neonates showed a hypomorphic interparietal bone, an exacerbation of the open fontanelles, and a further reduction in the hypoplastic clavicles compared to Runx2+/- neonates. Expression of osteoblast genes, including osteocalcin, osterix, periostin, and Hsp47, was markedly reduced in tibial RNA extracts from compound hemizygous mice, and osteoblasts from compound hemizygous mice exhibited increased proliferative capacity. Further, the reduced osteocalcin expression and hyperproliferative nature of osteoblasts from Cx43 deficient mice was rescued by Runx2 expression. In summary, these findings provide evidence that Cx43 and Runx2 functionally intersect in vivo to regulate cortical bone properties and affect osteoblast differentiation and proliferation, and likely contributes to aspects of the skeletal phenotype of Cx43 conditional knockout mice. © 2017 American Society for Bone and Mineral Research.
| S-EPMC5550348 | biostudies-literature
Project description:The synthesis of type I collagen, the main component of bone matrix, precedes the expression of Runx2, the earliest determinant of osteoblast differentiation. We hypothesized that the energetic needs of osteoblasts might explain this apparent paradox. We show here that glucose, the main nutrient of osteoblasts, is transported in these cells through Glut1, whose expression precedes that of Runx2. Glucose uptake favors osteoblast differentiation by suppressing the AMPK-dependent proteasomal degradation of Runx2 and promotes bone formation by inhibiting another function of AMPK. While RUNX2 cannot induce osteoblast differentiation when glucose uptake is compromised, raising blood glucose levels restores collagen synthesis in Runx2-null osteoblasts and initiates bone formation in Runx2-deficient embryos. Moreover, RUNX2 favors Glut1 expression, and this feedforward regulation between RUNX2 and Glut1 determines the onset of osteoblast differentiation during development and the extent of bone formation throughout life. These results reveal an unexpected intricacy between bone and glucose metabolism.
| S-EPMC4475280 | biostudies-literature
Project description:Bone undergoes continuous remodelling throughout adult life, and the equilibrium between bone formation by osteoblasts and bone resorption by osteoclasts defines the final bone mass. Here we show that Snail1 regulates this balance by controlling osteoblast differentiation. Snail1 is necessary for the early steps of osteoblast development, and it must be downregulated for their final differentiation. At the molecular level, Snail1 controls bone mass by repressing the transcription of both the osteoblast differentiation factor Runx2 and the vitamin D receptor (VDR) genes in osteoblasts. Sustained activation of Snail1 in transgenic mice provokes deficient osteoblast differentiation, which, together with the loss of vitamin D signalling in the bone, also impairs osteoclastogenesis. Indeed, the mineralisation of the bone matrix is severely affected, leading to hypocalcemia-independent osteomalacia. Our data show that the impact of Snail1 activity on the osteoblast population regulates the course of bone cells differentiation and ensures normal bone remodelling.
| S-EPMC2647771 | biostudies-literature
Project description:Runx2 is the master transcription factor for bone formation. Haploinsufficiency of RUNX2 is the genetic cause of cleidocranial dysplasia (CCD) that is characterized by hypoplastic clavicles and open fontanels. In this study, we found that Pin1, peptidyl prolyl cis-trans isomerase, is a critical regulator of Runx2 in vivo and in vitro. Pin1 mutant mice developed CCD-like phenotypes with hypoplastic clavicles and open fontanels as found in the Runx2+/- mice. In addition Runx2 protein level was significantly reduced in Pin1 mutant mice. Moreover Pin1 directly interacts with the Runx2 protein in a phosphorylation-dependent manner and subsequently stabilizes Runx2 protein. In the absence of Pin1, Runx2 is rapidly degraded by the ubiquitin-dependent protein degradation pathway. However, Pin1 overexpression strongly attenuated uniquitin-dependent Runx2 degradation. Collectively conformational change of Runx2 by Pin1 is essential for its protein stability and possibly enhances the level of active Runx2 in vivo.
| S-EPMC4051422 | biostudies-literature
Project description:The protein kinase D family of serine/threonine kinases, particularly PKD1, has been implicated in the regulation of a complex array of fundamental biological processes. However, its function and mechanism underlying PKD1-mediated the bone development and osteoblast differentiation are not fully understood. Here we demonstrate that loss of PKD1 function led to impaired bone development and osteoblast differentiation through STAT3 and p38 MAPK signaling using in vitro and in vivo bone-specific conditional PKD1-knockout (PKD1-KO) mice models. These mice developed markedly craniofacial dysplasia, scapula dysplasia, long bone length shortage and body weight decrease compared with wild-type littermates. Moreover, deletion of PKD1 in vivo reduced trabecular development and activity of osteoblast development, confirmed by Micro-CT and histological staining as well as expression of osteoblastic marker (OPN, Runx2 and OSX). Mechanistically, loss of PKD1 mediated the downregulation of osteoblast markers and impaired osteoblast differentiation through STAT3 and p38 MAPK signaling pathways. Taken together, these results demonstrated that PKD1 contributes to the osteoblast differentiation and bone development via elevation of osteoblast markers through activation of STAT3 and p38 MAPK signaling pathways.
| S-EPMC5233966 | biostudies-literature
Project description:Plant homeodomain finger protein 2 (PHF2), which contains a plant homeodomain and a Jumonji-C domain, is an epigenetic regulator that demethylates lysine 9 in histone 3 (H3K9me2). On the other hand, runt-related transcription factor 2 (Runx2) plays essential roles in bone development and regeneration. Given previous reports that the PHF2 mutation can cause dwarfism in mice and that PHF2 expression is correlated with that of Runx2 in differentiating thymocytes, we investigated whether PHF2 regulates Runx2-mediated bone formation. Overexpression of PHF2 facilitated bone development in newborn mice, and viral shRNA-mediated knockdown of PHF2 delayed calvarial bone regeneration in adult rats. In primary osteoblasts and C2C12 precursor cells, PHF2 enhances osteoblast differentiation by demethylating Runx2, while suppressor of variegation 3-9 homolog 1 (SUV39H1) inhibits bone formation by methylating it. The PHF2-Runx2 interaction is mediated by the Jumonji-C and Runt domains of the two proteins, respectively. The interaction between Runx2 and osteocalcin promoter is regulated by the methylation status of Runx2, i.e., the interaction is augmented when Runx2 is demethylated. Our results suggest that SUV39H1 and PHF2 reciprocally regulate osteoblast differentiation by modulating Runx2-driven transcription at the post-translational level. This study may provide a theoretical basis for the development of new therapeutic modalities for patients with impaired bone development or delayed fracture healing.
| S-EPMC4185351 | biostudies-literature
Project description:RUNX2, an essential transcription factor for osteoblast differentiation and bone formation is activated by ERK/MAP kinase-dependent phosphorylation. However, relationship between these early events and specific epigenetic modifications of chromatin during osteoblast differentiation have not been previously examined. Here, we explore these relationships using chromatin immunoprecipitation (ChIP) to detect chromatin modifications in RUNX2-binding regions of Bglap2 and Ibsp. Growth of MC3T3-E1c4 preosteoblast cells in differentiation conditions rapidly induced Bglap2 and lbsp mRNAs. For both genes, osteogenic stimulation increased chromatin-bound P-ERK, P-RUNX2, p300, and RNA polymerase II as well as histone H3K9 and H4K5 acetylation. The level of H3K4 di-methylation, another gene activation-associated histone mark, also increased. In contrast, levels of the gene repressive marks, H3K9 mono-, di-, and tri-methylation in the same regions were reduced. Inhibition of MAP kinase signaling blocked differentiation-dependent chromatin modifications and Bglap2 and Ibsp expression. To evaluate the role of RUNX2 phosphorylation in these responses, RUNX2-deficient C3H10T1/2 cells were transduced with adenovirus encoding wild type or phosphorylation site mutant RUNX2 (RUNX2 S301A/S319A). Wild type RUNX2, but not the non-phosphorylated mutant, increased H3K9 and H4K5 acetylation as well as chromatin-associated P-ERK, p300, and polymerase II. Thus, RUNX2 phosphorylation is necessary for subsequent epigenetic changes required for osteoblast gene expression. Taken together, this study reveals a molecular mechanism through which osteogenic genes are controlled by a MAPK and P-RUNX2-dependent process involving epigenetic modifications of specific promoter regions. J. Cell. Physiol. 232: 2427-2435, 2017. © 2016 Wiley Periodicals, Inc.
| S-EPMC5303561 | biostudies-literature
Project description:Osteoporosis, a disease characterized by both loss of bone mass and structural deterioration of bone, is the most common reason for a broken bone among the elderly. It is known that the attenuated differentiation ability of osteogenic cells has been regarded as one of the greatest contributors to age-related bone formation reduction. However, the effects of current therapies are still unsatisfactory. In this study we identify a novel long noncoding RNA AK045490 which is correlated with osteogenic differentiation and enriched in skeletal tissues of mice. In vitro analysis of bone-derived mesenchymal stem cells (BMSCs) showed that AK045490 inhibited osteoblast differentiation. In vivo inhibition of AK045490 by its small interfering RNA rescued bone formation in ovariectomized osteoporosis mice model. Mechanistically, AK045490 inhibited the nuclear translocation of β-catenin and downregulated the expression of TCF1, LEF1, and Runx2. The results suggest that Lnc-AK045490 suppresses β-catenin/TCF1/Runx2 signaling and inhibits osteoblast differentiation and bone formation, providing a novel mechanism of osteogenic differentiation and a potential drug target for osteoporosis.
| S-EPMC6941011 | biostudies-literature
Project description:Cyclophilin A (CypA) is a ubiquitously expressed and highly conserved protein with peptidyl-prolyl cis-trans isomerase activity that is involved in various biological activities by regulating protein folding and trafficking. Although CypA has been reported to positively regulate osteoblast differentiation, the mechanistic details remain largely unknown. In this study, we aimed to elucidate the mechanism of CypA-mediated regulation of osteoblast differentiation. Overexpression of CypA promoted osteoblast differentiation in bone morphogenic protein 4 (BMP4)-treated C2C12 cells, while knockdown of CypA inhibited osteoblast differentiation in BMP4-treated C2C12. CypA and Runx2 were shown to interact based on immunoprecipitation experiments and CypA increased Runx2 transcriptional activity in a dose-dependent manner. Our results indicate that this may be because CypA can increase the DNA binding affinity of Runx2 to Runx2 binding sites such as osteoblast-specific cis-acting element 2. Furthermore, to identify factors upstream of CypA in the regulation of osteoblast differentiation, various kinase inhibitors known to affect osteoblast differentiation were applied during osteogenesis. Akt inhibition resulted in the most significant suppression of osteogenesis in BMP4-induced C2C12 cells overexpressing CypA. Taken together, our results show that CypA positively regulates osteoblast differentiation by increasing the DNA binding affinity of Runx2, and Akt signaling is upstream of CypA.
| S-EPMC9409320 | biostudies-literature