Project description:We investigate cellular responses to traditional bioactive mineral-based nanomaterials, such as hydroxyapatite (nHA), whitlockite (nWH), silicon-dioxide (nSiO2), and the emerging synthetic 2D nanosilicates (nSi), on human mesenchymal stem cells (hMSCs). Specifically, using next-generation transcriptome sequencing (RNA-seq), we uncover key signaling pathways and transcriptome dynamics due to exposure to these inorganic nanomaterials. Whole-transcriptome sequencing identified a stabilized skeletal progenitor state in stem cells treated with nanosilicates that suggests endochondral differentiation of hMSCs, resulting in increased deposition of matrix mineralization compared with control or other treatment groups.
Project description:MicroRNAs (miRNAs, miRs) modulate a multitude of cellular events. Here, we identify functional miRNA-protein networks that regulate human monocyte-derived dendritic cell (MDDC) differentiation. MiRNA profiling revealed stage-specific differential expression of 20 miRNAs during days 1, 3 and 5 of MDDC differentiation. To identify and prioritize miRNA-protein networks for functional validation, we developed a target ranking algorithm that incorporates many features of miRNA regulatory networks. This system prioritized miR-21, miR-34a, and their cognate targets WNT1 and JAG1 for functional validation. Inhibition of both miR-21 and miR-34a stalled MDDC differentiation, as quantified by DC-SIGN/CD14 expression ratios, showing cooperative involvement of these miRNAs in MDDC differentiation. We confirmed that the 3’ UTRs of WNT1 and JAG1 were functional targets of these miRNAs and provide evidence that these targets were translationally suppressed. Significantly, exogenously added Wnt-1 and Jagged-1 also stalled MDDC differentiation, suggesting that miRNA mediated inhibition of endogenous WNT1 and JAG1 expression was important for proper MDDC differentiation. Finally, inhibition of miR-21 and miR-34a, or addition of Wnt-1 and Jagged-1 led to a decrease in endocytic capacity, a key function of immature DCs. Thus, our novel approach identified and validated some miRNA-protein networks involved in phenotypic and functional MDDC differentiation.
Project description:Antler primary growth center is located in the distal tip of growing antler with five consecutive tissue layers under the velvet skin. Because of blastema progenitor cells of outmost reserve mesenchymal layer with multipotent differentiation capacity, antler regeneration recapitulates embryonic skeletal development through endochondral os-sification process. To further decipher this modified endochondral ossification, we profile deer antler proteome atlas with 8000 proteins, covering the whole five layers that comprehensively represent the mesenchymal condensation, rapid mesenchymal proliferation, chondrocyte hypertrophy, cartilage mineralization. By integrating three clustering methods including WGCNA, Fuzzy C-means clustering, and Monotonic feature selector, we elucidate proteome dynamics within the growth center, identifying key factors and elucidating biological processes through GO enrichment analysis. Through comparative analysis of RNA-seq and Proteomic studies, our results reveal that mRNA exhibits greater fluctuations during the endochondral ossification process. This research offers a valuable model for investigating hub genes and their biological function involved in organ regeneration.
Project description:Appendicular skeletal growth and bone mass acquisition are controlled by a variety of growth factors, hormones, and mechanical forces in a dynamic process called endochondral ossification. In long bones, chondrocytes in the growth plate proliferate and undergo hypertrophy to drive bone lengthening and mineralization. Pleckstrin homology (PH) domain and leucine rich repeat phosphatase 1 and 2 (Phlpp1 and Phlpp2) are serine/threonine protein phosphatases that regulate cell proliferation, survival, and maturation via Akt, PKC, Raf1, S6k, and other intracellular signaling cascades. Germline deletion of Phlpp1 suppresses bone lengthening in part through parathyroid hormone receptor-dependent signaling in growth plate chondrocytes. Here, we demonstrate that Phlpp2 does not regulate endochondral ossification, and we define the molecular differences between Phlpp1 and Phlpp2 in chondrocytes. Phlpp2-/- mice are phenotypically indistinguishable from their wildtype (WT) littermates, with similar bone length, bone mass, and growth plate dynamics. Deletion of Phlpp2 had moderate effects on the chondrocyte transcriptome and proteome compared to WT cells. By contrast, Phlpp1/2-/- (double knockout) mice resembled Phlpp1-/- mice phenotypically and chondrocyte phospho-proteomes of Phlpp1-/- and Phlpp1/2-/- chondrocytes were different than WT and Phlpp2-/- chondrocyte phospho-proteomes. Data integration via multiparametric analysis identified alterations in Pdpk1 and Pak1/2 signaling pathways in chondrocytes lacking Phlpp1. In conclusion, these data demonstrate that Phlpp1, but not Phlpp2, regulates endochondral ossification through multiple and complex signaling cascades.
Project description:Endochondral ossification forms and grows the majority of the mammalian skeleton and is tightly controlled through gene regulatory networks. The forkhead box transcription factors Foxc1 and Foxc2 have been demonstrated to regulate aspects of osteoblast function in the formation of the skeleton but their roles in chondrocytes to control endochondral ossification are less clear. We demonstrate that Foxc1 expression is directly regulated by SOX9 activity, one of the earliest transcription factors to specify the chondrocyte lineages. Moreover we demonstrate that elevelated expression of Foxc1 promotes chondrocyte differentiation in mouse embryonic stem cells and loss of Foxc1 function inhibits chondrogenesis in vitro. Using chondrocyte-targeted deletion of Foxc1 and Foxc2 in mice, we reveal a role for these factors in chondrocyte differentiation in vivo. Loss of both Foxc1 and Foxc2 caused a general skeletal dysplasia predominantly affecting the vertebral column. The long bones of the limb were smaller and mineralization was reduced and organization of the growth plate was disrupted. In particular, the stacked columnar organization of the proliferative chondrocyte layer was reduced in size and cell proliferation in growth plate chondrocytes was reduced. Differential gene expression analysis indicated disrupted expression patterns in chondrogenesis and ossification genes throughout the entire process of endochondral ossification in Col2-cre;Foxc1Δ/Δ;Foxc2Δ/Δ embryos. Our results suggest that Foxc1 and Foxc2 are required for correct chondrocyte differentiation and function. Loss of both genes results in disorganization of the growth plate, reduced chondrocyte proliferation and delays in chondrocyte hypertrophy that prevents correct ossification of the endochondral skeleton.
Project description:C-type natriuretic peptide (CNP) has been recently identified as an important anabolic regulator of endochondral bone growth, but the molecular mechanism mediating these effects are not completely understood. Here we demonstrate that CNP activates the p38 MAP kinase pathway in chondrocytes and that pharmacological inhibition of p38 blocks the anabolic effects of CNP in a tibia organ culture system. We further show that CNP stimulates endochondral bone growth largely through expansion of the hypertrophic zone of the growth plate, while delaying mineralization. Both effects are reversed by p38 inhibition. We performed Affymetrix microarray analyses to identify CNP target genes in the organ culture system. These studies confirmed that hypertrophic chondrocytes are the main targets of CNP signaling in the growth plate, potentially because cGMP-dependent kinases I and II, important transducers of CNP signaling and are expressed at much higher levels in these cells than in other areas of the tibia. One of the genes most strongly induced by CNP was the Ptgs2 gene, encoding Cox2. Real-time PCR confirmed that Cox2 expression was induced by CNP in hypertrophic chondrocytes, but surprisingly in a p38-independent manner. Moreover, Cox2 inhibition – in contrast to p38 inhibition - did not block the anabolic effects of CNP. In summary, our data identify novel target genes of CNP and demonstrate that the p38 pathway is a novel, essential mediator of CNP effects on endochondral ossification, with potential implications for numerous skeletal diseases. Keywords: Growth plate zone comparison and treatment response analysis
Project description:Endochondral ossification (EO) is the natural route for the regeneration of large and mechanically challenged bone defects. Regeneration occurs via a fibrocartilagenous phase which turns into bone upon vascularization and the formation of a transient collagen type X extra cellular matrix. These two critical initiator of EO are mediated by Hedgehog proteins. We investigated a tissue engineering approach using Sonic Hedgehog (Shh) as a pleiotropic factor regulating the in vitro formation of a vascularized bone tissue precursor for in vivo endochondral bone formation. The tissue engineered graft was formed using human mesenchymal stem cells and prevascularized using human umbilical vein endothelial cells. We show that Shh induced, in vitro, the maturation of the engineered vascular network along with the expression of collagen type X which resulted, in vivo, in an improved vascularization and the rapid formation of large amounts of osteoids through EO. Osteoids further matured into, currently unmatched, clinically relevant amount of lamellar bone including osteoclasts, bone lining cells and bone marrow-like cavities. This result suggests that Hh is a master regulator of EO allowing for the formation of complex tissues with considerable therapeutic potential for bone regeneration. The effect of Cyclopamine on expression of Hedgehog, angiogenesis and axon guidance marker genes was analyzed by seeding a coculture of 92% hMSCs and 8% huvEC supplemented or not in cyclopamine, for 12 days
Project description:MicroRNAs (miRNAs, miRs) modulate a multitude of cellular events. Here, we identify functional miRNA-protein networks that regulate human monocyte-derived dendritic cell (MDDC) differentiation. MiRNA profiling revealed stage-specific differential expression of 20 miRNAs during days 1, 3 and 5 of MDDC differentiation. To identify and prioritize miRNA-protein networks for functional validation, we developed a target ranking algorithm that incorporates many features of miRNA regulatory networks. This system prioritized miR-21, miR-34a, and their cognate targets WNT1 and JAG1 for functional validation. Inhibition of both miR-21 and miR-34a stalled MDDC differentiation, as quantified by DC-SIGN/CD14 expression ratios, showing cooperative involvement of these miRNAs in MDDC differentiation. We confirmed that the 3â UTRs of WNT1 and JAG1 were functional targets of these miRNAs and provide evidence that these targets were translationally suppressed. Significantly, exogenously added Wnt-1 and Jagged-1 also stalled MDDC differentiation, suggesting that miRNA mediated inhibition of endogenous WNT1 and JAG1 expression was important for proper MDDC differentiation. Finally, inhibition of miR-21 and miR-34a, or addition of Wnt-1 and Jagged-1 led to a decrease in endocytic capacity, a key function of immature DCs. Thus, our novel approach identified and validated some miRNA-protein networks involved in phenotypic and functional MDDC differentiation. monocytes were cultured with GM-CSF and IL-4 for the indicated days (0,1, 3, and 5). Each timepoint was repeated in 3 independent donors (donor 1 , 2, and 3).