Project description:Primary osteoblasts from patients with end-stage kidney disease have defective maturation and mineralization characteristics in vivo and in vitro. This study was designed to evaluate signaling pathways associated with this abnormal maturation phenotype.
Project description:Here, we used single-cell RNA sequencing (scRNA-seq) to provide a high-resolution cellular taxonomy of freshly isolated primary human osteoblasts. Based on the gene expression patterns and cell lineage reconstruction, we identified three distinct clusters including preosteoblasts, mature osteoblasts, and an undetermined rare osteoblast subpopulation. Trajectory inference analysis suggested that the undetermined cluster may include osteoblast precursor cells which regulate the osteoblastogenesis process by giving rise to pre and mature osteoblasts. Investigation of the biological processes and signaling pathways enriched in each subpopulation revealed that in addition to bone formation, pre and undetermined osteoblasts may regulate both angiogenesis and hemopoiesis.
Project description:A microRNA array was performed using human primary osteoblasts (hOB) obtained from trabecular bone of postmenopausal women after knee replacement due to osteoarthritis in order to determine the miRNAs expressed in these osteoblastic cells.
Project description:Bone mineral density (BMD) is a highly heritable predictor of osteoporotic fracture. Genome wide association studies (GWAS) have identified hundreds of loci influencing BMD, but few have been functionally analyzed. In this study, we show that SNPs within a BMD locus on Chromosome 14q32.32 alter splicing and expression of PAR-1a/MARK3, a conserved serine/threonine kinase known to regulate bioenergetics, cell division and polarity. Mice lacking Mark3 either globally or selectively in osteoblasts have increased bone mass at maturity. RNA profiling from Mark3 deficient osteoblasts suggested changes in the expression of components of the Notch signaling pathway. Mark3 deficient osteoblasts exhibited greater matrix mineralization compared with controls that was accompanied by reduced Jag1/Hes1 expression and diminished downstream JNK signaling. Overexpression of Jag1 in Mark3 deficient osteoblasts both in vitro and in vivo normalized mineralization capacity and bone mass, respectively. Together, these findings reveal a mechanism whereby genetically regulated alterations in Mark3 expression perturb cell signaling in osteoblasts to influence bone mass.
