Project description:Human adult mesenchymal stromal cells (hMSC) have the potential to differentiate into chondrogenic, adipogenic or osteogenic lineages, providing a potential source for tissue regeneration. An important issue for efficient bone regeneration is to identify factors that can be targeted to promote the osteogenic potential of hMSCs. Using transcriptomic analysis, we found that integrin alpha5 (ITGA5) expression is upregulated during dexamethasone-induced hMSCs osteoblast differentiation. Gain-of-function studies showed that ITGA5 promotes the expression of osteoblast phenotypic markers as well as in vitro osteogenesis in hMSCs. Downregulation of endogenous ITGA5 using shRNA blunted osteoblast marker expression and osteogenic differentiation. Pharmacological and molecular analyses showed that the enhanced hMSCs osteoblast differentiation induced by ITGA5 was mediated by activation of FAK/ERK1/2-MAPKs and PI3K signaling pathways. Remarkably, activation of ITGA5 using a specific antibody that primes the integrin or a peptide that specifically activates ITGA5 was sufficient to enhance ERK1/2-MAPKs and PI3K signaling and to promote osteoblast differentiation and osteogenic capacity of hMSCs. We also demonstrate that hMSCs engineered to over-express ITGA5 exhibited a marked increase in their osteogenic potential in vivo. These findings not only reveal that ITGA5 is required for osteoblast differentiation of adult human MSCs but also provide a novel targeted strategy using ITGA5 agonists to promote the osteogenic capacity of hMSCs, which may be used for tissue regeneration in bone disorders where the recruitment or capacity of MSCs is compromised. Experiment Overall Design: Gene expression profiles were generated from bone marrow MSC before and 1, 3 and 7 days after stimulation with 10E-7M dexamethasone to study the early molecular processes of osteogenic differentiation. 3 replicates per timepoint.
Project description:Human adult mesenchymal stromal cells (hMSC) have the potential to differentiate into chondrogenic, adipogenic or osteogenic lineages, providing a potential source for tissue regeneration. An important issue for efficient bone regeneration is to identify factors that can be targeted to promote the osteogenic potential of hMSCs. Using transcriptomic analysis, we found that integrin alpha5 (ITGA5) expression is upregulated during dexamethasone-induced hMSCs osteoblast differentiation. Gain-of-function studies showed that ITGA5 promotes the expression of osteoblast phenotypic markers as well as in vitro osteogenesis in hMSCs. Downregulation of endogenous ITGA5 using shRNA blunted osteoblast marker expression and osteogenic differentiation. Pharmacological and molecular analyses showed that the enhanced hMSCs osteoblast differentiation induced by ITGA5 was mediated by activation of FAK/ERK1/2-MAPKs and PI3K signaling pathways. Remarkably, activation of ITGA5 using a specific antibody that primes the integrin or a peptide that specifically activates ITGA5 was sufficient to enhance ERK1/2-MAPKs and PI3K signaling and to promote osteoblast differentiation and osteogenic capacity of hMSCs. We also demonstrate that hMSCs engineered to over-express ITGA5 exhibited a marked increase in their osteogenic potential in vivo. These findings not only reveal that ITGA5 is required for osteoblast differentiation of adult human MSCs but also provide a novel targeted strategy using ITGA5 agonists to promote the osteogenic capacity of hMSCs, which may be used for tissue regeneration in bone disorders where the recruitment or capacity of MSCs is compromised. Keywords: Time course of osteogenic differentiation processes
Project description:Osteoradionecrosis of the jaw (ORNJ) is a complication after head and neck radiotherapy that severely affects patients’ quality of life. Currently, an overall understanding of microenvironmental factors of ORNJ is still lacking. Here, we reveal the activation of taurine metabolism in irradiated mandibular stromal cells with scRNA-Seq and the decrease of taurine in irradiated bone marrow mesenchymal stromal cells (BMSCs) with metabolomics. Compared to the unirradiated BMSCs, the taurine uptake of irradiated BMSCs increases. The taurine concentration in peripheral blood and jaws of irradiated mice are significantly lower than the unirradiated mice. Supplementation of taurine promotes osteogenic differentiation, decreases oxidative stress and DNA damage of irradiated BMSCs. Oral administration of taurine significantly promotes survival rate of irradiated mice and promotes osteogenesis of irradiated jaws. Our study sheds light on the role of taurine during the recovery of radiation-induced jaw injury, suggesting a potential non-invasive therapeutic means to combat ORNJ.
Project description:Cardiac calcification, commonly observed in age-related diseases, impairs heart function. However, its link to malignant tumors is poorly understood. Our study revealed that pericardial metallization occurs in up to 80% of breast cancer patients with pulmonary metastasis. We demonstrate a reciprocal relationship where breast cancer promotes pericardial calcification, which in turn accelerates cancer progression in both human patients and mice. Lung metastases increase macrophage and pre-osteoblast infiltration in the pericardial tissue, triggering inflammation and osteogenesis. Mechanistically, metastatic cancer cells in lungs highly express asparagine endopeptidase (AEP), which cleaves IGF2BP3 to enhance IGF2 level within these cells’ selves. These secreted AEP and IGF2 contribute to pericardial calcification by promoting osteoblast differentiation in heart tissue through activation of integrin αvβ5 and IGF1R respectively. Pharmacological inhibition of integrin αvβ5 and IGF1R effectively suppressed ectopic osteogenesis and disrupts the feedback loop from pericardial calcification to cancer progression. Taken together, these findings underscore the significance of managing pericardial calcification in breast cancer patients and offer potential treatment strategies.
Project description:The αNAC (alpha chain of the Nascent polypeptide-Associated Complex) transcriptional coregulator is developmentally expressed in osteoblasts and regulates osteoblast differentiation in vitro and in vivo. αNAC can activate or repress gene transcription, a function that is dynamically regulated by post-translational modification. Phosphorylation of residue Ser132 stimulates the sumoylation of αNAC on Lys127 to repress gene expression. Using in vitro kinase assays, we show that Ser132 phosphorylation is mediated by the DNA-dependent protein kinase catalytic subunit (DNA-PKcs). Pharmacological inhibition of DNA-PKcs kinase activity or gene silencing of Prkdc (encoding DNA-PKcs) in murine osteoblastic MC3T3-E1 cells and human adipose-derived mesenchymal stromal cells markedly enhanced osteogenesis and the expression of osteoblast differentiation marker genes. ChIP-seq identified Ezh2 as a target of the αNAC/DNA-PKcs signaling pathway. Mechanistically, inhibition of DNA-PKcs repressed Ezh2 expression, induced cell cycle block, and increased osteogenesis by significantly enhancing the bone morphogenetic protein 2 (BMP-2) response in osteoblasts and other mesenchymal cells. Importantly, in vivo inhibition of the kinase enhanced bone biomechanical properties, and bones from osteoblast-specific conditional Prkdc-knockout mice exhibited increased stiffness. In conclusion, DNA-PKcs is a negative regulator of osteoblast differentiation, and therefore DNA-PKcs inhibitors may have therapeutic potential for bone regeneration and metabolic bone diseases.
Project description:Msh homeobox 1 (MSX1) is a transcriptional factor regulating embryonic development of limbs and craniofacial tissues including bone and teeth. The purpose of this study was to investigate contribution of MSX1 to the osteogenic potential and calcification-related phenotypic expression of dental pulp stromal/mesenchymal cells isolated from human teeth. Immunohistochemisitry of a 3 week-old mouse molar showed that MSX1 protein was localized to odontoblasts and pulpal mesenchymal cells at different levels and in different manners depending upon the position of the cells in pulp tissue. When dental pulp stromal/mesenchymal cells were exposed to osteogenesis-induction medium, runt-related transcription factor-2 (RUNX2), bone morphogenetic protein-2 (BMP2), alkaline phosphatase (ALPL) and osteocalcin (OCN) mRNA levels, as well as alkaline phosphatase activity, increased on days 4-12, and, thereafter, the matrix was calcified on day 14. However, knockdown of MSX1 with small interfering RNA abolished this induction of the osteoblast-related gene expression, alkaline phosphatase activity and calcification. Interestingly, DNA microarray and quantative PCR analyses revealed that the MSX1 knockdown induced the sterol regulatory element-binding protein 2 (SREBP2) transcriptional factor and its downstream target genes in cholesterol-synthesis pathway. Inhibition of cholesterol synthesis enhances osteoblast differentiation of various mesenchymal cells. Thus, MSX1 may down-regulate the cholesterol synthesis-related genes to ensure osteoblast differentiation of dental pulp stromal/mesenchymal cells.
Project description:In vivo, osteogenesis is tightly connected with capillaries and endothelium assumed to be one of the main regulators of osteogenic differentiation of underling mesenchymal cell. In our experiments in vitro, we cultured human osteoblasts and human umbilical vein cord endothelial cells (HUVEC) in osteogenic conditions in direct joint culture and in separated joint culture where cells were separated with membrane permeable for proteins, but not for the cells. We revealed that in direct co-cultivation endothelial cells enhance osteoblast differentiation, but in separated co-cultures endothelium completely inhibit osteogenic differentiation. To understand molecular mechanisms of these osteoinductive/osteosupressive properties we performed shotgun proteomics analysis of control cultures and cells from joint cultures. To separate cells from direct co-culture we used magnetic sorting.
Project description:In mouse bone marrow, mesenchymal stem cells (MSC) has the potential to form osteocytes, adipocytes and cartilage. In the process of osteogenesis, MSCs differenetiate into stromal cells, such as CAR cells. Osteoblast is responsible for the formation of osteocytes and osteoblasts may be differentiated from a subset of CAR cells. Dmp1-Cre targeted CAR cells are thought to enrich for a osteoblast progenitor population. We used microarrays to detail the gene expression profiles among Dmp1-Cre targeted and non-targeted CAR cells. Gene expression diffferences were compared to support the hypothesis that Dmp1-Cre targeted CAR cells may be enriched for osteoblast progenitors. Dmp1-Cre targeted and non-targeted CAR cells were FACS sorted from three mice. RNA were extracted from these sorted cells and processed for microarray using Affymetrix mogene 1.0 ST chip. Cells from one mouse represent one sample
Project description:Growing evidence indicates that tumor-associated stroma plays a negative role in human colorectal cancer (CRC). Nature of specific stromal cell populations involved and mechanisms underlying their negative impact remain to be fully understood. In this study we describe the expansion from human primary CRCs of a mesenchymal cell population, referred to as tumor-associated stromal cells (TASCs), resembling bone marrow-derived mesenchymal stem cells (BM-MSCs) in morphology, phenotypes and differentiation potential. We found that, upon co-culture with tumor cells, TASCs acquire membrane-bound TGF-mbTGF-expression, a phenomenon mediated by v6 integrin. MbTGF-expression proved to be critical for triggering epithelial-to-mesenchymal transition (EMT) in tumor cells, eventually leading to enhanced dissemination of circulating tumor cells and increased metastasis formation, in an orthotopic mouse model. Our data identify CRC-associated mesenchymal stem-like cells as critical EMT initiators and suggest mbTGF- as potential novel therapeutic target.
Project description:In mouse bone marrow, mesenchymal stem cells (MSC) has the potential to form osteocytes, adipocytes and cartilage. In the process of osteogenesis, MSCs differenetiate into stromal cells, such as CAR cells. Osteoblast is responsible for the formation of osteocytes and osteoblasts may be differentiated from a subset of CAR cells. Dmp1-Cre targeted CAR cells are thought to enrich for a osteoblast progenitor population. We used microarrays to detail the gene expression profiles among Dmp1-Cre targeted and non-targeted CAR cells. Gene expression diffferences were compared to support the hypothesis that Dmp1-Cre targeted CAR cells may be enriched for osteoblast progenitors.