Project description:To investigate gene expression changes induced by the fungicide cyproconazole that affect skeletal development in zebrafish, zebrafish embryos were treated with cyproconazole followed by mRNA sequencing.
Project description:Background: Gout is an inflammatory arthritis associated with increased bone anabolism and a higher risk of ectopic bone formation. Colchicine, used to prevent and treat acute gouty flares, inhibits microtubule polymerization and has been described to promote osteoblastogenesis. In bone disorders such as osteoporosis, disruption of the osteoblast–adipocyte balance contributes to pathology, yet no therapies directly target bone marrow adiposity. Thus, we decided to investigate the impact of colchicine on the osteoblast-adipocyte balance. Methods: C3H10T1/2 mesenchymal stem cells were differentiated to both cell fates in the presence or absence of colchicine. Differentiation was assessed by studying differentiation phenotypes, as well as adipocytic and osteoblastic marker genes. Disrupting microtubule homeostasis through stathmin (STMN1) silencing was employed to mimic colchicine effects on differentiation. Proteomic analysis was performed to gain further insight into colchicine’s effects on adipogenesis. Results: Colchicine promoted transcriptional changes consistent with osteoblastogenic commitment and inhibited adipogenesis, as evidenced by reduced intracellular lipid accumulation and downregulation of adipogenic marker genes. These effects were observed following both continuous and transient exposure (median fold-change across adipogenic markers 0.41 and 0.59, respectively). Consistent with colchicine-induced microtubules destabilization, microtubule disruption by STMN1 silencing also suppressed adipogenic differentiation (median fold-change = 0.66), suggesting that colchicine’s anti-adipogenic effect may be due to its impact on the cytoskeleton. Conclusions: These findings indicate that colchicine can suppress adipogenic differentiation while favouring osteoblast commitment in mesenchymal stem cells. Although further validation in relevant preclinical models required, its efficacy following transient exposure supports the exploration of site-specific strategies that limit systemic toxicity.
Project description:In order to study FGFR3’s role in cranial vault development, we generated the first fgfr3 loss-of-function zebrafish (fgfr3lof1/lof1). The mutant fish exhibited major changes in the craniofacial skeleton, with a lack of sutures, abnormal frontal and parietal bones, and the presence of ectopic bones. In order to define cellular and molecular processes responsible for this phenotype, we performed single-cell RNA sequencing of cranial vault cells from fgfr3lof1/lof1 and fgfr3+/+ zebrafish. Our data allow us to define transcriptomic profile of each osteogenic subpopulation involved in cranial vault formation and we revealed a defect in osteoblast differentiation associated with changes in the extracellular matrix. These findings demonstrate that fgfr3 is a positive regulator of osteogenesis and we conclude that changes in the extracellular matrix within growing bone impair cell-cell communication, mineralization, and new osteoblast recruitment.
Project description:Abstract: Prostate cancer bone metastasis is still one of the most fatal cancer diagnosis for men. Survival of the circulating prostate tumor cells and their adaptation strategy to survive in the bone niche is the key point to determining metastasis in early cancer stages. The promoter of SFRP2, a WNT signaling regulator, is hypermethylated in many cancer types including prostate cancer. Moreover, SFRP2 can positively modulate osteogenic differentiation in vitro and in vivo. Here, we showed SFRP2 overexpression in the prostate cancer cell line PC3 induces an epithelial mesenchymal transition (EMT), increases the attachment, and modifies the transcriptome towards an osteoblast-like phenotype (osteomimicry) in a collagen 1‑dependent manner. Our data reflects a novel molecular mechanism how metastasizing prostate cancer cells might increase their chance to survive within bone tissue.
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:Background: Osteoblast differentiation requires the coordinated stepwise expression of multiple genes. Histone deacetylase inhibitors (HDIs) accelerate the osteoblast differentiation process by blocking the activity of histone deacetylases (HDACs), which alter gene expression by modifying chromatin structure. We previously demonstrated that HDIs and HDAC3 shRNAs accelerate matrix mineralization and the expression of osteoblast maturation genes (e.g. alkaline phosphatase, osteocalcin). Identifying other genes that are differentially regulated by HDIs might identify new pathways that contribute to osteoblast differentiation. Results: To identify other osteoblast genes that are altered early by HDIs, we incubated MC3T3-E1 preosteoblasts with HDIs (trichostatin A, MS-275, or valproic acid) for 18 hours in osteogenic conditions. The promotion of osteoblast differentiation by HDIs in this experiment was confirmed by osteogenic assays. Gene expression profiles relative to vehicle-treated cells were assessed by microarray analysis with Affymetrix GeneChip 430 2.0 arrays. The regulation of several genes by HDIs in MC3T3-E1 cells and primary osteoblasts was verified by quantitative real-time PCR. Nine genes were differentially regulated by at least two-fold after exposure to each of the three HDIs and six were verified by PCR in osteoblasts. Four of the verified genes (solute carrier family 9 isoform 3 regulator 1 (Slc9a3r1), sorbitol dehydrogenase 1, a kinase anchor protein, and glutathione S-transferase alpha 4) were induced. Two genes (proteasome subunit, beta type 10 and adaptor-related protein complex AP-4 sigma 1) were suppressed. We also identified eight growth factors and growth factor receptor genes that are significantly altered by each of the HDIs, including Frizzled related proteins 1 and 4, which modulate the Wnt signaling pathway. Conclusions: This study identifies osteoblast genes that are regulated early by HDIs and indicates pathways that might promote osteoblast maturation following HDI exposure. One gene whose upregulation following HDI treatment is consistent with this notion is Slc9a3r1. Also known as NHERF1, Slc9a3r1 is required for optimal bone density. Similarly, the regulation of Wnt receptor genes indicates that this crucial pathway in osteoblast development is also affected by HDIs. These data support the hypothesis that HDIs regulate the expression of genes that promote osteoblast differentiation and maturation. Keywords: gene expression