Project description:Purpose: Endothelial cells respond to changes in subendothelial stiffness altering their proliferation, migration and barrier integrity but whether that is due to transcriptional reprogramming was largely unknown. Using RNA-Sequencing, we performed gene expression profiling for two endothelial cell types grown on soft or stiff matrices: primary human umbilical vein endothelial cells (HUVEC) and immortalized human microvascular endothelial cells (HMEC-1), to understand whether subendothelial stiffness-dependent changes in endothelial cell mechanics are due to transcriptional regulation. Methods and Results: By analyzing the differentially expressed genes between all samples we found that endothelial cell type rather that subendothelial stiffness is the primary determinant of the endothelial cell transcriptome. Both cell types respond to changes in their subendothelial stiffness by increasing the traction stresses they exert on stiffer as opposed to softer matrices, however it is apparently not the endothelial cell transcriptome that regulates this universal biomechanical response to subendothelial stiffness. Only a handful of genes were differentially expressed in each cell type in a stiffness-dependent manner, and none were shared between the two cell types examined. In contrast, thousands of genes were differentially regulated in HUVEC as compared to HMEC-1. HUVEC (but not HMEC-1) upregulate expression of TGF-2 on stiffer matrices, and also enhance their endogenous TGF-2 expression and their cell-matrix traction stresses in response to application of exogenous TGF-2. Conclusions: Altogether, these findings provide insights into the relationship between subendothelial stiffness, endothelial mechanics and variation of the transcriptome between distinct endothelial cell types, and reveal that subendothelial stiffness while critically impacting endothelial cell mechanics is minimally altering their transcriptome.
Project description:Hippocampal rat neurons have been cultured on very soft (100 Pa) and stiff (10 kPa) hydrogels for 7 days. On DIV7, the RNA has been extracted and sequenced. The goal of this experiment is to understand why neurons mature more quickly on soft gels compared to stiff gels.
Project description:Mesenchymal stromal/stem cells (MSCs) are a heterogeneous population of multipotent progenitors that contribute to tissue regeneration and homeostasis. MSCs assess extracellular elasticity by probing resistance to applied forces via adhesion, cytoskeletal, and nuclear mechanotransducers, that direct differentiation toward soft or stiff tissue lineages. Even under controlled conditions, MSC differentiation exhibits substantial cell-to-cell variation that remains poorly characterized. By single-cell transcriptional profiling of naïve, matrix-conditioned, and early differentiation state cells, we identified distinct MSC subpopulations with distinct mechanosensitivities, differentiation capacities, and cell cycling. We showed that soft matrices support adipogenesis of multipotent cells and endochondral ossification of non-adipogenic cells, whereas intramembranous ossification and pre-osteoblast proliferation are enhanced by stiff matrices. Using diffusion pseudotime mapping, we delineated hierarchical matrix-directed differentiation and identified mechanoresponsive genes. We found that tropomyosin-1 (TPM1) is highly sensitive to stiffness cues both at RNA and protein levels and that changes in expression of TPM1 determine adipogenic or osteogenic fates. Thus, cell-to-cell variation in tropomyosin-mediated matrix-sensing contributes to impaired differentiation with implications to the biomedical potential of MSCs.
Project description:Purpose: To identify genes and the molecular pathways involved in the MSCs response to extracellular matrix stiffness, we performed RNA-sequencing of MSCs which cultured in soft (2 kPa) and stiff (18 kPa) SA hydrogels. Methods: mRNA profiles of MSCs cultured in soft (2 kPa) and stiff (18 kPa) SA hydrogel for 48 h were generated by deep sequencing, in quadruplicate, using Illumina HiSeq 2000. Results: Using an optimized data analysis workflow, we identified 33950 transcripts in MSCs with BWA workflow. Conclusions: Our results present the detailed analysis of MSCs transcriptomes cultured in soft (2 kPa) and stiff (18 kPa) matrix, and found that matrix stiffness dominated multiple mRNA pathways in MSCs.
Project description:Global transcriptome analysis showed that human lymphatic endothelial cells (LECs) grown on a soft matrix exhibit increased GATA2 expression, concomitant with a GATA2-dependent upregulation of genes involved in cell migration and lymphangiogenesis, including the key lymphangiogenic growth factor receptor VEGFR3. Affymetrix GeneChip analysis revealed regulation of 2771 transcripts above or below a 1.4-fold change (log2 fold change >0.5 or <-0.5) threshold on soft versus stiff matrices. Moreover, 406 (27%) of the 1485 transcripts that were increased and 207 (16 %) of the 1286 transcripts that were decreased on soft matrix were regulated in a GATA2 dependent manner.
Project description:Aim: To examine transcriptional changes in DLD-1 cells exposed to softer matrices (2 kPa and 55 kPa) and identify the chromosomes that are enriched with maximmally deregulated genes Methods: DLD-1 cells (otherwise growing on stiff tissue culture plastic substrates) were exposed to softer matrices for 90 minutes and to collagen coated glass coverslips (served as control) served as control) Results: RNA sequencing revealed nearly equivalent transcriptional deregulation in cells on both the polyacrylamide matrices (783 genes up and 872 genes down on 2 kPa, 649 genes up and 783 genes down on 55 kPa) when compared to cells on glass. Additionally, GO classification revealed that unique sets of transcriptionally deregulated genes (log fold≥2) belonged to pathways associated with transcription regulation, chromatin organization, cell cycle and DNA damage/repair Results: We identified chromosomes 1, 2, 3, 6, 7, 10, 12, 14, 17 and 19 to be maximally enriched with the deregulated genes on softer matrices (log fold≥2), while chromosomes 13, 18 and 21 showed minimal enrichment of deregulated genes. We also examined the spatial organization of chromosome 1, 18 and 19 territories in cells on softer matrices (using 3D-FISH) and observed that these chromosomes were mislocalized away from their conserved nuclear locations Conclusions: Our study reports the transcriptomic changes in DLD-1 cells upon lowering of extracellular substrate stiffnes and its impact on the spatial positioning of chromosome territories
Project description:Dysregulation of vascular stiffness and cellular metabolism occur early in pulmonary hypertension (PH). Yet, the mechanisms by which biophysical properties of extracellular matrix relate to metabolic processes and downstream PH phenotypes remain undefined. In cultured endothelial and smooth muscle cells and confirmed in PH-diseased human samples, we found that ECM stiffening activates the mechanosensitive factors YAP/TAZ to increase glycolysis and induce glutaminase (GLS) expression and glutaminolysis. Glutaminolysis replenishes aspartate for anabolic biosynthesis, thus sustaining proliferation and migration within stiff ECM. In vitro GLS inhibition blocks aspartate production, consequently reprogramming entire cellular proliferative pathways, while aspartate restores proliferation. In a rat model in vivo, GLS inhibition prevents hemodynamic and histologic manifestations of PH. Thus, mechanical ECM stiffening sustains vascular cell growth and migration through YAP/TAZ-dependent glutaminolysis â a paradigm that advances our understanding of the connections of mechanical stimuli with dysregulated vascular metabolism and identifies new metabolic drug targets in PH. We used microarrays to decipher the global program of gene expression involved in response to matrix stiffening and determined the implication of glutaminolysis (GLS) in these process PAECs were transfected with an siRNA control (siNC) or a siRNA against GLS (siGLS) and cultivated on soft hydrogel (1kPa) or stiff hydrogel (50kPa). After 48h of transfection cells were lysate and RNA extract for hybridization on Affymetrix microarrays.
Project description:This SuperSeries is composed of the following subset Series: GSE28374: DNA methylation of miRNA genes in HMEC and HMF GSE28375: Histone H3 acetylation of miRNA genes in HMEC and HMF GSE28376: Histone H3 lysine 27 trimethylation of miRNA genes in HMEC and HMF GSE28377: Histone H3 lysine 4 trimethylation of miRNA genes in HMEC and HMF GSE28378: Histone H3 lysine 9 dimethylation of miRNA genes in HMEC and HMF Refer to individual Series