Project description:Venkatraman2012 - Interplay between PLS and TSP1 in TGF-β1 activation The interplay between PLS (Plasmin) and TSP1 (Thrombospondin-1) in TGF-β1 (Transforming growth factor-β1)is shown using mathematical modelling and in vitro experimentents. This model is described in the article: Plasmin triggers a switch-like decrease in thrombospondin-dependent activation of TGF-β1. Venkatraman L, Chia SM, Narmada BC, White JK, Bhowmick SS, Forbes Dewey C Jr, So PT, Tucker-Kellogg L, Yu H. Biophys J. 2012 Sep 5;103(5):1060-8. Abstract: Transforming growth factor-β1 (TGF-β1) is a potent regulator of extracellular matrix production, wound healing, differentiation, and immune response, and is implicated in the progression of fibrotic diseases and cancer. Extracellular activation of TGF-β1 from its latent form provides spatiotemporal control over TGF-β1 signaling, but the current understanding of TGF-β1 activation does not emphasize cross talk between activators. Plasmin (PLS) and thrombospondin-1 (TSP1) have been studied individually as activators of TGF-β1, and in this work we used a systems-level approach with mathematical modeling and in vitro experiments to study the interplay between PLS and TSP1 in TGF-β1 activation. Simulations and steady-state analysis predicted a switch-like bistable transition between two levels of active TGF-β1, with an inverse correlation between PLS and TSP1. In particular, the model predicted that increasing PLS breaks a TSP1-TGF-β1 positive feedback loop and causes an unexpected net decrease in TGF-β1 activation. To test these predictions in vitro, we treated rat hepatocytes and hepatic stellate cells with PLS, which caused proteolytic cleavage of TSP1 and decreased activation of TGF-β1. The TGF-β1 activation levels showed a cooperative dose response, and a test of hysteresis in the cocultured cells validated that TGF-β1 activation is bistable. We conclude that switch-like behavior arises from natural competition between two distinct modes of TGF-β1 activation: a TSP1-mediated mode of high activation and a PLS-mediated mode of low activation. This switch suggests an explanation for the unexpected effects of the plasminogen activation system on TGF-β1 in fibrotic diseases in vivo, as well as novel prognostic and therapeutic approaches for diseases with TGF-β dysregulation. This model is hosted on BioModels Database and identified by: MODEL1303130000 . To cite BioModels Database, please use: BioModels Database: An enhanced, curated and annotated resource for published quantitative kinetic models . To the extent possible under law, all copyright and related or neighbouring rights to this encoded model have been dedicated to the public domain worldwide. Please refer to CC0 Public Domain Dedication for more information.

Project description:The metabolic adaptation of eukaryotic cells to hypoxia involves increasing dependence upon glycolytic ATP production, an event with consequences for both cell bioenergetics and cell fate. This response is regulated at the transcriptional level by HIF-1-dependent transcriptional upregulation of all ten glycolytic enzymes. However, this response alone does not account for the levels of ATP produced in hypoxia. Here, we investigated additional mechanisms of regulating glycolysis in hypoxia. We found that both intestinal epithelial cells treated with inhibitors of transcription and translation and human platelets (which lack nuclei) maintained the capacity for hypoxia-induced glycolysis, suggesting the involvement of a non-transcriptional component to the hypoxia-induced metabolic switch to a highly glycolytic phenotype. Mass spectrometric analysis of the interactome of immunoprecipitated rate-limiting glycolytic enzymes identified hypoxia-sensitive complexes comprising multiple glycolytic enzymes and glucose transporters in intestinal epithelial cells. Surprisingly, the formation of glycolytic complexes, though not dependent upon transcription, occurs via a HIF-1?-dependent mechanism, suggesting that HIF-1? may play a moonlighting role in the formation / maintenance of glycolytic complexes. Furthermore, we provide evidence for the presence of HIF-1? in cytosolic fractions of hypoxic cells which physically associated with the glucose transporter GLUT1 and the glycolytic enzyme PFKP in a hypoxia-sensitive manner. In conclusion, we hypothesize that HIF-1? plays a role in initiation and/or maintenance of glycolytic complexes in intestinal epithelial cells under hypoxic conditions in a manner which optimizes catalytic efficiency of the pathway by facilitating substrate channeling of glycolytic intermediates between sequential pathway enzymes. In hypoxia, cells undergo a metabolic switch to increased glycolysis. This has important implications for cell behavior, phenotype, and fate in both healthy and cancerous cells. Here we describe a mechanism by which HIF-1, in addition to increasing glycolytic enzyme expression, promotes glycolysis via the formation of a metabolic complex.

Project description:Hypertrophic scars, which result from aberrant fibrosis and disorganized collagen synthesis by skin fibroblasts, emerge due to disrupted wound healing processes. These scars present significant psychosocial and functional challenges to affected individuals. The current treatment limitations largely arise from an incomplete understanding of the underlying mechanisms of hypertrophic scar development. Recent studies, however, have shed light on the potential of exosomal non-coding RNAs interventions to mitigate hypertrophic scar proliferation. This research assesses the impact of exosomes derived from adipose-derived stem cells (ADSCs-Exos) on hypertrophic scar formation using a rabbit ear model. We employed Hematoxylin and Eosin staining, Masson’s Trichrome staining, and Immunohistochemical staining techniques to track scar progression. Our comprehensive analysis encompassed the differential expression of non-coding RNAs, enrichment analyses of functional pathways, protein-protein interaction studies, and miRNA-mRNA interaction investigations. The results reveal a marked alteration in the expression levels of long non-coding RNAs and microRNAs following ADSCs-Exos treatment, with little changes observed in circular RNAs. Notably, miR-194 emerges as a critical regulator within the signaling pathways that govern hypertrophic scar formation. Dual-luciferase assays indicated a significant reduction in the promoter activity of TGF-β1 after miR-194 overexpression. Quantitative reverse transcription PCR and Western blotting assays further validated the decrease in TGF-β1 expression in the treated samples. Moreover, the treatment resulted in diminished levels of inflammatory markers IL-1β, TNF-α, and IL-10. In vivo evidence strongly supports the role of miR-194 in attenuating hypertrophic scar formation through the suppression of TGF-β1. Our findings endorse the strategic use of ADSCs-Exos, particularly through miR-194 modulation, as an effective strategy for reducing scar formation and lowering pro-inflammatory and fibrotic indicators like TGF-β1. Therefore, this study advocates for the targeted application of ADSCs-Exos, with an emphasis on miR-194 modulation, as a promising approach to managing proliferative scarring.

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Distinct phenotypes induced by acute hypoxia and TGF-β1 in human adult cardiac fibroblasts

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