Project description:The bone marrow in mammals house both hematopoietic and mesenchymal cells that are responsible for sustaining blood and bone cell production, respectively, throughout adult life. Although the hematopoietic system is well understood, the molecular identities, hierarchy of the marrow mesenchymal cells and their respective contribution to bone homeostasis are just beginning to be unraveled. By employing single-cell RNA sequencing (scRNA-seq) technology, we have discovered a subset of bone marrow mesenchymal cells co-expressing adiponectin (Adipoq) and osterix (Osx) which are traditionally considered adipocyte or osteoblast markers, respectively. Trajectory analyses predict the Adipoq+Osx+ bi-marker cells to be common progenitors for osteoblasts and marrow adipogenic lineage cells. Lineage tracing with Osx-CreERT2 or Adipoq-CreERT2 supports that the bi-marker cells give rise to both osteoblasts and adipocytes in vivo. Imaging studies localize the bi-marker cells to the endosteal bone niche. The data therefore support the hypothesis that Adipoq+Osx+ bi-marker cells are adipo-osteoprogenitors attuned to the physiological milieu in the bone marrow. The studies have shed light on the role of the adipo- osteoprogenitors in bone physiology and pathophysiology.
Project description:Prenatal dexamethasone exposure (PDE) has long-term consequences in bone development. we investigated how PDE exerts persistent effect on bone metabolism in mouse offspring. Our results showed that PDE offspring exhibited reduced bone mass, fewer osteoblasts and diminished osteoprogenitors proliferation.And PDE increased MKP-1 expression, while decreasing H3 lysine 9 dimethylation (H3K9me2) at Mkp-1 gene locus. Mechanistically, dexamethasone suppressed osteoprogenitors proliferation by upregulating MKP-1 expression, notably through the inhibition of H3K9me2 modifications, which promoted demethylation and transcriptional activation of the Mkp-1 gene. Importantly, restoring histone methylation balance with PFI-90 treatment blocked the inhibitory effects of PDE on MAPK signaling in osteoprogenitors, and mitigated the detrimental impact of PDE on osteoprogenitor proliferation and bone development in the offspring. Therefore,we performed ChIP-seq for H3K9me2 to identify its role in related epigenetic changes.
Project description:Clinical evidence has established that concomitant traumatic brain injury accelerates bone healing, but the underlying mechanism is unclear. This study showed that after TBI, injured neurons, mainly those in the hippocampus, released osteogenic microRNA (miRNA)-enriched exosomes, which targeted osteoprogenitors in bone to stimulate bone formation. Importantly, increased fibronectin expression on exosomal surface contributed to targeting of osteoprogenitors in bone by TBI exosomes, thereby implying that modification of the exosome surface fibronectin could be used in bone-targeted drug delivery. Together, our findings have established a novel role of central regulation in bone formation and a clear link between injured neurons and osteogenitors, both in animals and clinical settings.
Project description:We defined iMoP as a new precursor subset in murine bone marrow. The aim of this expression analysis was the identification of transcriptional differences between iMoP and their progeny cMoP.
Project description:This SuperSeries is composed of the following subset Series: GSE17569: Gene expression profile of murine bone marrow endosteal populations (1) GSE17570: Gene expression profile of murine bone marrow endosteal populations (2) Refer to individual Series
Project description:In March 2006, murine Bone Marrow Stromal Cells (BMSC) were flown in the Soyuz 12S to the International Space Station to investigate the effects of microgravity on their osteogenic potential in a three-dimensional environment. BMSC were grown in porous bioceramic Skelite disks (Φ 9 mm x T 1.2 mm). The constructs were exposed to microgravity for ca. 8 days, then fixed for RNA extraction. While the flight experiment was performed in fully automated hardware inside the KUBIK incubator, one group of control samples were incubated inside manually operated hardwares (flight control), and the other control group was incubated under routine laboratory conditions (lab control). The altered gene expression profile was analyzed by Mouse Gene 1.0 ST array (Affymetrix) representing whole-transcript coverage. Each one of the 28853 genes is represented on the array by approximately 26 probes spread across the full length of the gene, providing a more complete and more accurate picture of gene expression than the 3â based expression array design. A few days of microgravity were sufficient to determinate, at least at the molecular level, an effect in the BMSC; this response expressed a stress condition able to determinate consequences on several compartments and cellular functions. In particular, it seems to promote a gene expression, known to be associated with neurogenic activity (e.g. axon guidance), perhaps promoting the BMSC capability to be committed in that direction. The osteo-induction, by dexamethasone-based medium, due to the short duration of stimulation, did not have the possibility to manifest itself at the phenotypic level but only partially at the molecular level. Keywords: gene expression array-based, count Comparison of microgravity effects on bone marrow stromal cells maintained both in growth and in osteo-inductive conditions.