Project description:SP7/Osterix is a transcription factor critical for osteoblast maturation and bone formation. We identidied a missense variant (c.926C>G:p.S309W) in SP7 in a patient with a unique high turnover bone disease. Mice with the corresponding variant similarly showed a complex skeletal phenotype distinct from that of Sp7-null mice. We therefore performed ChIP-Seq in primary chondrocytes to study how the mutation alters the genomic binding of SP7.
Project description:S309W mutation of SP7 is found in a patient with craniosynostosis, cranial hyperostosis, and long bone fragility. In this experiment we aimed to compare the effect of the mutation on SP7 genomic binding in the presence of DLX5
Project description:Sp7/Osterix is a master regulator of osteoblast specification. To identify transcripts profile in Sp7 positive osteoblast, we performed RNA-seq on primary mouse calvarial cells obtained from Sp7-GFP reporter mice at P1. By hierarchical clustering using transcriptional profiles for chondrocytes and mouse embryonic fibroblasts (MEFs) together with the osteoblast data, we identified cell-type enriched gene expression signatures in osteoblasts, chondrocytes and MEFs. In conjunction with Sp7 ChIP-seq in osteoblast, we identified putative Sp7 targets which underlie the osteoblast regulatory program.
Project description:Some cuboidal osteoblasts differentiate into bone-embedded, dendrite-bearing osteocytes through the poorly-understood process of osteocytogenesis. Here, we report that the transcription factor Sp7 plays an essential role in osteocytogenesis. Severe defects in bone integrity and osteocyte dendrite morphology are noted in mice lacking Sp7 at the stage of the osteoblast-to-osteocyte transition. In osteocytes, Sp7 controls expression of a neuronally-enriched gene network. Analysis of the osteocyte-specific Sp7 cistrome reveals distinct genomic binding motifs and target sites distinct from those in osteoblasts. Amongst osteocyte-specific Sp7 targets, the secreted peptide osteocrin rescues Sp7-deficient defects. Single-cell transcriptional profiling of cells undergoing osteocytogenesis identifies novel Sp7-dependent transitional cell types enriched in genes linked to human fracture risk. Finally, humans with an SP7 R316C mutation display osteocyte morphology defects similar to those observed in mouse models. These findings demonstrate that cuboidal osteoblasts use a neuronally-enriched Sp7/osteocrin gene expression program to differentiate into dendrite-bearing osteocytes.
Project description:Some cuboidal osteoblasts differentiate into bone-embedded, dendrite-bearing osteocytes through the poorly-understood process of osteocytogenesis. Here, we report that the transcription factor Sp7 plays an essential role in osteocytogenesis. Severe defects in bone integrity and osteocyte dendrite morphology are noted in mice lacking Sp7 at the stage of the osteoblast-to-osteocyte transition. In osteocytes, Sp7 controls expression of a neuronally-enriched gene network. Analysis of the osteocyte-specific Sp7 cistrome reveals distinct genomic binding motifs and target sites distinct from those in osteoblasts. Amongst osteocyte-specific Sp7 targets, the secreted peptide osteocrin rescues Sp7-deficient defects. Single-cell transcriptional profiling of cells undergoing osteocytogenesis identifies novel Sp7-dependent transitional cell types enriched in genes linked to human fracture risk. Finally, humans with an SP7 R316C mutation display osteocyte morphology defects similar to those observed in mouse models. These findings demonstrate that cuboidal osteoblasts use a neuronally-enriched Sp7/osteocrin gene expression program to differentiate into dendrite-bearing osteocytes.
Project description:Some cuboidal osteoblasts differentiate into bone-embedded, dendrite-bearing osteocytes through the poorly-understood process of osteocytogenesis. Here, we report that the transcription factor Sp7 plays an essential role in osteocytogenesis. Severe defects in bone integrity and osteocyte dendrite morphology are noted in mice lacking Sp7 at the stage of the osteoblast-to-osteocyte transition. In osteocytes, Sp7 controls expression of a neuronally-enriched gene network. Analysis of the osteocyte-specific Sp7 cistrome reveals distinct genomic binding motifs and target sites distinct from those in osteoblasts. Amongst osteocyte-specific Sp7 targets, the secreted peptide osteocrin rescues Sp7-deficient defects. Single-cell transcriptional profiling of cells undergoing osteocytogenesis identifies novel Sp7-dependent transitional cell types enriched in genes linked to human fracture risk. Finally, humans with an SP7 R316C mutation display osteocyte morphology defects similar to those observed in mouse models. These findings demonstrate that cuboidal osteoblasts use a neuronally-enriched Sp7/osteocrin gene expression program to differentiate into dendrite-bearing osteocytes.
Project description:Sp7/Osterix is a master regulator of osteoblast specification. To identify the Sp7-mediated gene regulatory network in osteoblasts, we performed Sp7 ChIP-seq on primary mouse calvarial osteoblasts comparing the DNA binding profile with the transcriptional profile of Sp7-positive osteoblasts. Analysis of these identified a network of Sp7 regulated osteoblast targets and provides a new insight into the mode of Sp7 action in osteoblast. To further study for the Sp7 mode, we performed ChIP-seq for Sp1, Sp7, Dlx5, as a potential Sp7 partner identified in this study and mutated Sp7 which has mutations in the zinc finger domain, by using in vitro system with a pre-osteoblast mouse cell line, MC3T3E1.
Project description:To investigate the role of Notch2 in the inflammatory response in chondrocytes, we cultured primary chondrocytes derived from wild type and Notch2 mutant mice and treated TNFalpha or vehicle. We then performed gene expression profiling analysis using data obtained from RNA-seq of wild type and Notch2 mutant chondrocytes.
Project description:The transgenic zebrafish line Tg(sp7:sp7-GFP) (ulg071 Tg) was used to obtain fluorescent cells through FACS sorting. Two populations were identifed: P1 displaying low fluorescence, P2 displaying high fluorescence. Cells were collected and sumitted to RNA-Seq