Project description:Background: Our group has previously shown that disruption of TGFβ signaling in mouse limb mesenchyme resulted in arrested tendon formation (Pryce et at, 2007). To examine the role of TGFβ signaling in later stages of tendon development, the TGF-beta type II receptor gene (Tgfbr2) was targeted in the Scleraxis (Scx)-expressing cell lineage using the Cre-lox recombination system. We find that tendon development was not disrupted in mutant (Tgfbr2;ScxCre) embryos. However, shortly after birth tenocytes underwent dedifferentiation in which the cell lost differentiation markers and reverted to a more stem/progenitor state. Purpose: To determine gene expression changes in Tgfbr2;ScxCre mutant tendon cells. Methods: We performed scRNA-seq for transcriptome changes in P7 mutant tendon cells, a stage at which the majority of the mutant cells is dedifferentiated. Briefly, tendons from P7 mutant and wild-type (as a control) pups were harvested and enzymatically digested. The released cells were then subjected to scRNA-seq analysis using 10x Genomics platform. Results: Using unsupervised hierarchical clustering, we identified two major clusters corresponding to mutant (dedifferentiated) cells and wild-type tenocytes in the respective samples. Findings from the pairwise comparison of the gene set between the P7 wild-type tenocyte and mutant cell clusters do not only lend support to our notion that the mutant cells lost their differentiation state, but also suggest the possibility of induction of some developmental programs in these cells, a general feature in cellular dedifferentiation. Conclusions: TGF-beta signaling is critical for maintenance of the tendon cell fate.
Project description:Adhesion formation after flexor tendon repair remains a clinical problem. Early postoperative motion after tendon repair has been demonstrated to reduce adhesion formation while increasing tendon strength. It is hypothesized that during mobilization, tendon cells experience mechanical shear forces that alter their biology in a fashion that reduces scar formation but also activates key genes involved in tendon healing. To test this hypothesis, primary intrinsic tenocyte cultures were established from flexor tendons of 20 Sprague-Dawley rats and sheared at 50 rpm (0.41 Pa) using a cone viscometer for 6 and 12 hours. Total RNA was harvested and compared with time-matched unsheared controls using cDNA microarrays and Northern blot analysis. Microarray analysis demonstrated that mechanical shear stress induced an overall "antifibrotic" expression pattern with decreased transcription of collagen type I and collagen type III. Shear stress down-regulated profibrotic molecules in the platelet-derived growth factor, insulin-like growth factor, and fibroblast growth factor signaling pathways. In addition, shear stress induced an overall decrease in transforming growth factor (TGF)-beta signaling pathway molecules with down-regulation of TGF-beta2, TGF-beta3, TGF-RI, and TGF-RII expression. Moreover, sheared tendon cells increased expression of matrix metalloproteinases and decreased expression of tissue inhibitors of metalloproteinase, an expression pattern consistent with an antifibrotic increase in extracellular matrix degradation. However, up-regulation of genes implicated in tendon healing, specifically, vascular endothelial growth factor-A and several bone morphogenetic proteins. Interestingly, the known mechanoresponsive gene, TGF-beta1, also implicated in tendon healing, was differentially up-regulated by shear stress. Northern blot validation of our results for TGF-beta1, TGF-beta2, TGF-beta3, and collagen type I demonstrated direct correlation with microarray data. Groups of assays that are related as part of a time series. Computed
Project description:Adhesion formation after flexor tendon repair remains a clinical problem. Early postoperative motion after tendon repair has been demonstrated to reduce adhesion formation while increasing tendon strength. It is hypothesized that during mobilization, tendon cells experience mechanical shear forces that alter their biology in a fashion that reduces scar formation but also activates key genes involved in tendon healing. To test this hypothesis, primary intrinsic tenocyte cultures were established from flexor tendons of 20 Sprague-Dawley rats and sheared at 50 rpm (0.41 Pa) using a cone viscometer for 6 and 12 hours. Total RNA was harvested and compared with time-matched unsheared controls using cDNA microarrays and Northern blot analysis. Microarray analysis demonstrated that mechanical shear stress induced an overall "antifibrotic" expression pattern with decreased transcription of collagen type I and collagen type III. Shear stress down-regulated profibrotic molecules in the platelet-derived growth factor, insulin-like growth factor, and fibroblast growth factor signaling pathways. In addition, shear stress induced an overall decrease in transforming growth factor (TGF)-beta signaling pathway molecules with down-regulation of TGF-beta2, TGF-beta3, TGF-RI, and TGF-RII expression. Moreover, sheared tendon cells increased expression of matrix metalloproteinases and decreased expression of tissue inhibitors of metalloproteinase, an expression pattern consistent with an antifibrotic increase in extracellular matrix degradation. However, up-regulation of genes implicated in tendon healing, specifically, vascular endothelial growth factor-A and several bone morphogenetic proteins. Interestingly, the known mechanoresponsive gene, TGF-beta1, also implicated in tendon healing, was differentially up-regulated by shear stress. Northern blot validation of our results for TGF-beta1, TGF-beta2, TGF-beta3, and collagen type I demonstrated direct correlation with microarray data.
Project description:Adhesion formation after flexor tendon repair remains a clinical problem. Early postoperative motion after tendon repair has been demonstrated to reduce adhesion formation while increasing tendon strength. It is hypothesized that during mobilization, tendon cells experience mechanical shear forces that alter their biology in a fashion that reduces scar formation but also activates key genes involved in tendon healing. To test this hypothesis, primary intrinsic tenocyte cultures were established from flexor tendons of 20 Sprague-Dawley rats and sheared at 50 rpm (0.41 Pa) using a cone viscometer for 6 and 12 hours. Total RNA was harvested and compared with time-matched unsheared controls using cDNA microarrays and Northern blot analysis. Microarray analysis demonstrated that mechanical shear stress induced an overall "antifibrotic" expression pattern with decreased transcription of collagen type I and collagen type III. Shear stress down-regulated profibrotic molecules in the platelet-derived growth factor, insulin-like growth factor, and fibroblast growth factor signaling pathways. In addition, shear stress induced an overall decrease in transforming growth factor (TGF)-beta signaling pathway molecules with down-regulation of TGF-beta2, TGF-beta3, TGF-RI, and TGF-RII expression. Moreover, sheared tendon cells increased expression of matrix metalloproteinases and decreased expression of tissue inhibitors of metalloproteinase, an expression pattern consistent with an antifibrotic increase in extracellular matrix degradation. However, up-regulation of genes implicated in tendon healing, specifically, vascular endothelial growth factor-A and several bone morphogenetic proteins. Interestingly, the known mechanoresponsive gene, TGF-beta1, also implicated in tendon healing, was differentially up-regulated by shear stress. Northern blot validation of our results for TGF-beta1, TGF-beta2, TGF-beta3, and collagen type I demonstrated direct correlation with microarray data. Groups of assays that are related as part of a time series. Keywords: time_series_design
Project description:Here, we investigated the effect of conditioned media (CM) obtained from cultured mouse DRG neurons on Tppp3+ cells, mainly on proliferation and differentiation potential. Peripheral afferent neurons terminate at the surfaces of tendons, yet their role after injury beyond nociceptive functions remain unclear. Using transgenic animal models, sensory neurons were found to sprout after Achilles tendon injury in domains of Nerve growth factor (NGF) expression. Conditional deletion of Ngf in either myeloid or mesenchymal cell types led to tendon repair defects – findings phenocopied by inactivation of TrkA (Tropomyosin receptor kinase A) using a knockin mouse model. A combination of spatial and single cell transcriptomics revealed dysregulated inflammatory and TGF signaling upon lack of neural input. Utilizing sural nerve transection in reporter animals, we identified that neural input is required for proper expansion of Tppp3+ tendon sheath progenitor cells (TSPCs) after injury, and in vitro approaches implicated TGF signaling activation in Tppp3+ TSPC neural response. Finally, in a translational approach, activation of TrkA+ sensory neurons using a partial agonist led to a significant increase in TGF signaling, TSPC expansion, and improved tendon repair. Collectively, these data implicate peripheral afferent neural networks in the coordinated acute tendon injury response, and identify candidate molecules to speed the reparative process.
Project description:To investigate the role of TGF-β1-regulated miRNAs in the progression of RMS,we performed comprehensive miRMA microarray analysis on RNA derived from typical RMS cell lines and TGF-β1 knock-down cell lines. We identified a novel set of TGF-β1-related miRNAs.