Project description:Hypertrophic scars arise from dysregulated wound healing under prolonged mechanical tension, causing disfiguring fibrosis. However, limited preclinical models replicate key features of human tension-induced scarring. We developed an innovative murine model utilizing suture anchoring to impose persistent transverse-axial stretch across healing incisions, mimicking excessive wound tension that leads to hypertrophy clinically. Dorsal paired incisions were generated in mice, with wound edges on the upper back sutured to the rib cage while leaving wound edges on the lower back relaxed. This localized anchoring restrained wound contraction, maintaining high tension throughout remodeling analogous to scars widening under stress. Stretched upper wounds developed profound fibrotic changes compared to relaxed controls. Scars induced by suture-anchored tension displayed macroscopic hypertrophy, hardness, erythema, and pruritis up to 3 months. Histologically, scars induced by suture-anchored tension were hypercellular, hypervascular, hyperproliferative with disorganized extracellular matrix deposition, and displayed molecular hallmarks of hypertrophic fibrosis. MiRNA sequencing revealed the different signature in suture-anchored tension induced hypertrophic scars compared to control normal scars.
Project description:Chromatin-based functional genomic analyses and genomewide association studies (GWASs) together implicate enhancers as critical elements influencing gene expression and risk for common diseases. Here, we performed systematic chromatin and transcriptome pro- filing in human pancreatic islets. Integrated analysis of islet data with those generated by the ENCODE project in nine cell types identified specific and significant enrichment of type 2 diabetes and related quantitative trait GWAS variants in islet enhancers. Our integrated chromatin maps reveal that most enhancers are short (median = 0.8 kb). Each cell type also contains a substantial number of more extended (≥3 kb) enhancers. Interestingly, these stretch enhancers are often tissue-specific and overlap locus control regions, suggesting that they are important chromatin regulatory beacons. Indeed, we show that (i) tissue specificity of enhancers and nearby gene expression increase with enhancer length; (ii) neighborhoods containing stretch enhancers are enriched for important cell type– specific genes; and (iii) GWAS variants associated with traits rele- vant to a particular cell type are more enriched in stretch enhancers compared with short enhancers. Reporter constructs containing stretch enhancer sequences exhibited tissue-specific activity in cell culture experiments and in transgenic mice. These results suggest that stretch enhancers are critical chromatin elements for coordinating cell type–specific regulatory programs and that sequence variation in stretch enhancers affects risk of major common human diseases. Integrated analysis of islet chromatin modification and transcriptome data with those generated by the ENCODE project. NISC Comparative Sequencing Program
Project description:The goal of this study was to examine the effect of the major axis of biaxial mechanical stretch on cardiac myocyte gene expression and to identify the signaling pathways and transcription factors regulating these changes. Neonatal cardiac myocytes were cultured on a micropatterned substrate, and the primary stretch axis was applied either parallel or transverse to the myofibril direction. RNA sequencing was conducted to study whole genomic expression changes after acute cardiac myocyte stretch. The results showed a more robust gene response to longitudinal than to transverse stretch. After 30 minutes of stretch, 53 and 168 genes were considered differentially expressed (DE) from transverse and longitudinal stretch, respectively. After 4 hours, the number of DE genes increased to 795 in longitudinal stretch while it decreased to 35 in transverse stretch. Gene ontology term (GO) analysis indicated enrichment of TF activity and protein kinase activity by both stretch axes; whereas longitudinal but not transverse stretch caused expression of genes involved in sarcomere organization and cytoskeletal protein binding.
Project description:The goal of this study was to identify microRNAs that are modulated by cyclic stretch. miRNA-Seq was performed comparing samples from cultured E16.5 mouse cardiomyocytes exposed to either cyclic stretch of 16% at 1Hz for 24h or static conditions.
Project description:Chromatin-based functional genomic analyses and genomewide association studies (GWASs) together implicate enhancers as critical elements influencing gene expression and risk for common diseases. Here, we performed systematic chromatin and transcriptome pro- filing in human pancreatic islets. Integrated analysis of islet data with those generated by the ENCODE project in nine cell types identified specific and significant enrichment of type 2 diabetes and related quantitative trait GWAS variants in islet enhancers. Our integrated chromatin maps reveal that most enhancers are short (median = 0.8 kb). Each cell type also contains a substantial number of more extended (≥3 kb) enhancers. Interestingly, these stretch enhancers are often tissue-specific and overlap locus control regions, suggesting that they are important chromatin regulatory beacons. Indeed, we show that (i) tissue specificity of enhancers and nearby gene expression increase with enhancer length; (ii) neighborhoods containing stretch enhancers are enriched for important cell type– specific genes; and (iii) GWAS variants associated with traits rele- vant to a particular cell type are more enriched in stretch enhancers compared with short enhancers. Reporter constructs containing stretch enhancer sequences exhibited tissue-specific activity in cell culture experiments and in transgenic mice. These results suggest that stretch enhancers are critical chromatin elements for coordinating cell type–specific regulatory programs and that sequence variation in stretch enhancers affects risk of major common human diseases.
Project description:The aim of the experiment was to determine the effect of cyclic stretch-relaxation ("stretch") on gene expression patterns in normal diploid human bladder smooth muscle cells. Cells plated on silicone elastomer bottomed 6-well culture dishes were grown to ~80% confluence, serum-depleted for 48h and subjected to cyclic stretch-relaxation at 20% elongation for 4h. Cells seeded in stretch plates but not subjected to stretch served as controls. Total RNA was extracted from both groups of cells, reverse-transcribed, biotin-labeled, fragmented and hybridized to HG-U133A. Four biological replicates were generated for each treatment group (non-stretched or stretched).