Project description:To investigation the role of PTH and Kindlin-2 in bone development, we performed single-cell RNA-sequencing. From Con-veh, Con-PTH, cKO-veh, cKO-PTH, we profiled more than 20k single cells, including multi-potent mesenchymal stromal cells (MSC), osteoprogenitors, osteoblasts, chondrocytes, fibroblasts, endothelial cells, smooth muscle cells, skeletal muscle cells, pericytes, and schwann cells. We found proportion of part of these cells were significant altered by PTH or Kindlin-2 loss, especially for MSC, osteoblast, chondrocyte, and fibroblast. Transcriptomic analysis revealed gene expression was dramatically regulated by PTH or Kindlin-2 loss.
Project description:Irradiation induced bone marrow ablation ultimately enhanced PTH anabolic effects in bone. B6 mice at 10 days of age were sub-lethally irradiated and treated with PTH 24h later for 5 days. 24h post last-injection, bone marrow was flushed with Trizol and RNA isolated and purified. Microarray analyses was performed to determine differential differences in PTH effects in non-irradiated vs. irradiated bone marrow. Triplicates of 4 groups (total of 12 samples) which include: Nonirradiated Vehicle, Nonirradiated PTH, Irradiated Vehicle and Irradiated PTH
Project description:Irradiation induced bone marrow ablation ultimately enhanced PTH anabolic effects in bone. B6 mice at 10 days of age were sub-lethally irradiated and treated with PTH 24h later for 5 days. 24h post last-injection, bone marrow was flushed with Trizol and RNA isolated and purified. Microarray analyses was performed to determine differential differences in PTH effects in non-irradiated vs. irradiated bone marrow.
Project description:Glucocorticoids (GC) and parathyroid hormone (PTH) are widely used therapeutic endocrine hormones where their effects on bone and joint arise from actions on multiple skeletal cell types. In osteocytes, GC and PTH exert opposing effects on perilacunar canalicular remodeling (PLR). Suppressed PLR can impair bone quality and joint homeostasis, including in GC-induced osteonecrosis. However, combined effects of GC and PTH on PLR are unknown. Focusing on subchondral bone and joint homeostasis, we hypothesize that PTH, a PLR agonist, could rescue GC-suppressed PLR. The skeletal effects of GC and PTH, alone or combined, were examined in male and female mice by micro-computed tomography, mechanical testing, histology, and gene expression analysis. For each outcome, females were more responsive to GC and PTH than males. GC and PTH exerted regional differences, with GC increasing trabecular bone volume but reducing cortical bone thickness, stiffness, and ultimate force. Despite PTH’s anabolic effects on trabecular bone, it did not rescue GC’s catabolic effects on cortical bone. Likewise, cartilage integrity and subchondral bone apoptosis, alkaline phosphatase activity, and osteocyte lacunocanalicular networks showed no evidence that PTH could offset GC-dependent effects. Rather, GC and PTH each increased cortical bone gene expression implicated in bone resorption by osteoclasts and osteocytes, including Acp5, Mmp13, Atp6v0d2, Ctsk, differences maintained when GC and PTH were combined. Since PTH is insufficient to rescue GC’s effects on young female mouse bone, future studies are needed to determine if osteocyte PLR suppression, due to GC, aging, or other factors, can be offset by a PLR agonist.
Project description:Bone homeostasis is regulated by hormones such as parathyroid hormone (PTH). While PTH can stimulate osteo-progenitor expansion and bone synthesis, how the PTH-signaling intensity in progenitors is controlled is unclear. Endochondral bone osteoblasts arise from perichondrium-derived osteoprogenitors and hypertrophic chondrocytes (HC). We found, via single-cell transcriptomics, HC descendent cells activate membrane-type 1 metalloproteinase 14 (MMP14) and the PTH pathway as they transition to osteoblasts in neonatal and adult mice. Unlike Mmp14 global knockouts, postnatal day 10 (p10) HC lineage-specific Mmp14 null mutants (Mmp14ΔHC) produce more bone. Mechanistically, MMP14 cleaves the extracellular domain of PTH1R, dampening PTH signaling, and consistent with the implied regulatory role, in Mmp14ΔHC mutants, PTH signaling is enhanced. We found HC-derived osteoblasts contribute ~50% of osteogenesis promoted by treatment with PTH 1-34 and this response was amplified in Mmp14ΔHC. MMP14 control of PTH signaling likely applies also to both HC- and non-HC-derived osteoblasts because their transcriptomes are highly similar. Our study identifies a novel paradigm of MMP14 activity-mediated modulation of PTH signaling in the osteoblast lineage, contributing new insights into bone metabolism with therapeutic significance for bone-wasting diseases.
Project description:Chromodomain helicase DNA-binding protein 7 (CHD7) is an ATP-dependent chromatin remodeling enzyme, functioning as chromatin reader to conduct epigenetic modification. Its effect on osteogenic differentiation of human dental follicle cells (hDFCs) remains unclear. Here we show CHD7 expression increases with osteogenic differentiation. knockdown of CHD7 impairs the osteogenic ability of hDFCs, characterized by reduced alkaline phosphatase activity and mineralization, and decreased expression of osteogenesis-related genes. Conversely, CHD7 overexpression enhances the osteogenic differentiation of hDFCs. Mechanically, RNA-seq analyses revealed the down-regulated enrichment of PTH (parathyroid hormone)/PTH1R (parathyroid hormone receptor-1) signaling pathway after CHD7 knockdown. We found the expression of PTH1R positively correlates with CHD7. Importantly, overexpression of PTH1R in CHD7-knockdown hDFCs partially rescued the impaired osteogenic differentiation. Our research demonstrates that CHD7 regulates the osteogenic differentiation of hDFCs by regulating the transcription of PTH1R.
Project description:Osteoclasts form special integrin-mediated adhesion structures called sealing zones that enable them to adhere to and resorb bone. Sealing zones consist mainly of densely packed podosomes tightly inter-connected by actin fibers. Their formation requires the presence of the hematopoietic integrin regulator kindlin-3. In the current study, we investigated osteoclasts and their adhesion structures in kindlin-3 hypomorphic mice expressing only 5-10% of kindlin-3. Low kindlin-3 expression reduces integrin activity, results in impaired osteoclast adhesion and signaling, and delays cell spreading. Despite these defects, in vitro generated kindlin-3-hypomorphic osteoclasts arrange their podosomes into adhesion patches and belts, which show abnormal podosome and actin organization. Remarkably, kindlin-3-hypomorphic osteoclasts form sealing zones when cultured on calcified matrix in vitro and on bone surface in vivo. However, functional assays as well as immunohistochemical staining and electron micrographs of bone sections showed that they fail to properly seal the resorption lacunae, which is required for secreted proteases to be able to digest bone matrix. This results in mild osteopetrosis. Our study reveals a new, hitherto understudied function of kindlin-3 as an essential organizer of integrin-mediated adhesion structures, such as sealing zones.
Project description:The osteocytic actions of glucocorticoids on bone mass, mechanical properties, or perilacunar remodeling outcomes are not rescued by PTH
Project description:Kindlin-2, an integrin-interacting FERM-domain-containing protein, has been known to play critical roles for tumor progression. However, the role of Kindlin-2 in renal cell carcinoma (RCC) progression has not been reported. We aim to investigate the role of Kindlin-2 in the progression of RCC and the underlying mechanisms. To uncover the related pathway in which Kindlin-2 is involved to promote clear cell renal cell carcinoma progression, ACHN control and Kindlin-2-depleting cells were analyzed by Affymetrix GeneChip human Gene 1.0 ST Arrays. ACHN cells were transfected with control short hairpin RNA (shRNA) or Kindlin-2 shRNA. ACHN control and Kindlin-2-depleting cells cDNAs were hybridized to Affymetrix GeneChip Human Gene 1.0 ST arrays. Data were analyzed by Expression Console 1.4.1.
Project description:After demonstrating that the bone-forming ability of mice is altered by blocking PTH1R entry into the nucleus, We performed RNA-seq on BMSCs from Pth1rΔNLS individuals and wild-type individuals to explore the mechanism behind this phenomenon.