Next-generation sequencing facilitates quantitative analysis of rat BMSCs in soft or stiff SA hydrogel
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ABSTRACT: 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:Tissue stiffness is a critical prognostic factor in breast cancer and is associated with metastatic progression. Here we show an alternative and complementary hypothesis of tumor progression whereby physiological matrix stiffness affects the quantity and protein cargo of small EVs produced by cancer cells, which in turn aid cancer cell dissemination. Primary patient breast tissue produces significantly more EVs from stiff tumor tissue than soft tumor adjacent tissue. EVs released by cancer cells on matrices that model human breast tumors (25 kPa; stiff EVs) feature increased adhesion molecule presentation (ITGα2β1, ITGα6β4, ITGα6β1, CD44) compared to EVs from softer normal tissue (0.5 kPa; soft EVs), which facilitates their binding to extracellular matrix (ECM) protein collagen IV, and a 3-fold increase in homing ability to distant organs in mice. In a zebrafish xenograft model, stiff EVs aid cancer cell dissemination. Moreover, normal, resident lung fibroblasts treated with stiff and soft EVs change their gene expression profiles to adopt a cancer associated fibroblast (CAF) phenotype. These findings show that EV quantity, cargo, and function depend heavily on the mechanical properties of the extracellular microenvironment.
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:Mechanotransduction plays a critical role in regulating cell growth, proliferation, and metabolism. Cells respond to mechanical signals, which ultimately induces gene expression. However, the underlying mechanisms of this gene regulation remain largely unclear. In previous research, we discovered that the ubiquitin-conjugating enzymes UBE2A and UBE2B translocate between the cytoplasm and nucleus in a force-dependent manner. Additionally, we confirmed that UBE2A and UBE2B ubiquitinate histone H2B at lysine 120 (K120) when cells are cultured on a stiff substrate. In this study, we employed Chromatin Immunoprecipitation (ChIP) to investigate the distribution of H2B mono-ubiquitination in human skeletal muscle (hsSKM) cells cultured on substrates of varying stiffness—soft (0.2 kPa) and stiff (64 kPa).
Project description:Understanding how cells respond to the mechanics of their environment, and what affect senescence may have on this response, is important to gain a better understanding of mechanobiology, both in health and ageing-associated pathology. This experiment assessed the mRNA levels in early and late passage donor-matched human mesenchymal stem cells (MSCs) cultured for four days on soft (2 kPa) or stiff (25 kPa) collagen-I coated polyacrylamide (PA) gels. A minimum of three donors were analysed under each condition. Protein coding RNAs were sequenced with Illumina HiSeq technology. In a parallel experiment, protein was quantified by mass spectrometry proteomics.
Project description:To investigate the genes differentially expressed upon plating on top of matrixes with different stiffness, we compared the expression profiles of MDA-MB-231 breast cancer cells plated on a stiff substrate (plastic) with the same cells plated on a soft substrate (hydrogels 0.7 kPa). Keywords: expression profiling by array
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:The tumour microenvironment is a critical element involved in tumour progression and responsiveness to therapies. Using functionalized tunable stiffness hydrogel, mimicking the mechanical properties of healthy and tumour tissues, we explore how the stiffness of the microenvironment can influence cancer cells by generating RNA-seq transcriptional profiles of 4T1 mouse breast cancer cells cultured on soft vs stiff polyacrylamide hydrogels for 24 hours.
Project description:Background: The differentiation of pericytes into myofibroblasts causes microvascular degeneration, extracellular matrix (ECM) accumulation, and tissue stiffening, characteristics of fibrotic diseases. It is unclear how pericyte-myofibroblast differentiation is regulated in the microvascular environment. Our previous study established a novel two-dimensional platform for coculturing microvascular endothelial cells (ECs) and pericytes derived from the same tissue. This study investigated how ECM stiffness regulated microvascular ECs, pericytes, and their interactions. Methods: Primary microvessels were cultured in the TGM2D medium. Stiff ECM was prepared by incubating ECM solution in regular culture dishes for one hour followed by PBS wash. Soft ECM with Young’s modulus of approximately 6 kPa was used unless otherwise noted. Bone grafts were prepared from the rat skull. Immunostaining, RNA sequencing, qRT-PCR, western blotting, and knockdown experiments were performed on the cells. Results: Primary microvascular pericytes differentiated into myofibroblasts (NG2+αSMA+) on stiff ECM, even with the TGFβ signaling inhibitor A83-01. Soft ECM and A83-01 cooperatively maintained microvascular stability while inhibiting pericyte-myofibroblast differentiation (NG2+αSMA-/low). We thus defined two pericyte subpopulations: primary (NG2+αSMA-/low) and activated (NG2+αSMA+) pericytes. Soft ECM promoted microvascular regeneration and inhibited fibrosis in bone graft transplantation in vivo. As Integrins are the major mechanosensor, we performed qRT-PCR screening of Integrin family members selected from RNA sequencing data. We found that Integrin β1 (Itgb1) was the major subunit downregulated by soft ECM and A83-01 treatment. Knocking down Itgb1 suppressed myofibroblast differentiation on stiff ECM. Interestingly, ITGB1 phosphorylation (Y783) was mainly located on microvascular ECs on stiff ECM, which promoted EC secretion of paracrine factors, including CTGF, to induce pericyte-myofibroblast differentiation. CTGF knockdown or monoclonal antibody treatment partially reduced myofibroblast differentiation, implying the participation of multiple pathways in fibrosis formation. Conclusions: Microvascular ECs mediate ECM stiffness-induced pericyte-myofibroblast differentiation through paracrine signaling.
Project description:To further examine the gene expression of isolated primary mouse proximal tubular epithelial cells (mPTECs) during ex vivo culture, we have employed whole genome microarray expression profiling as a discovery platform to identify genes with the potential to distinguish the key regulatory transcription factor which was significantly altered. Primary culuture of mPTECs were cultured on culture dishes for 1 and 3 days. As compared to freshly isolated mPTECs, a 1801-gene consensus signature was identified that distinguished between day 1 and and day 3 samples. Within these genes, 78 transcriptal factors were dramatically altered. Expression of three genes (KLF5, KLF4, and CCND1) from this signature was quantified in the same RNA samples by RT-PCR. The proliferation of mouse proximal tubular epithelial cells in ex vivo culture depends on matrix stiffness. Combined analysis of the microarray and experimental data revealed that Krüppel-like factor 5 (Klf5) was the most upregulated transcription factor accompanied by Krüppel-like factor 4 (Klf4) downregulation when cells on stiff matrix. These changes were reversed by soft matrix via ERK inactivation. Knockdown of Klf5 or forced-expression of Klf4 inhibited stiff matrix-induced cell spreading and proliferation, suggesting that Klf5/Klf4 act as positive/negative regulators, respectively. Moreover, stiff matrix-activated ERK increased the protein level and nuclear translocation of mechanosensitive Yes-associated protein 1 (YAP1), which is reported to prevent Klf5 degradation. Finally, in vivo model of unilateral ureteral obstruction (UUO) revealed that matrix stiffness-regulated Klf5/Klf4 is related to the pathogenesis of renal fibrosis. In the dilated tubules of obstructed kidney, ERK/YAP1/Klf5/Cyclin D1 axis were upregulated and Klf4 was downregulated. Inhibition of collagen crosslinking by lysyl oxidase inhibitor alleviated UUO-induced tubular dilatation and proliferation with preserving Klf4 and suppressing the ERK/YAP1/Klf5/Cyclin D1 axis. This study unravels a novel mechanism how matrix stiffness regulates cellular proliferation and highlights the importance of matrix stiffness-modulated Klf5/Klf4 in the regulation of renal physiological functions and fibrosis progression. Gene expression in cultured mPTECs was measured at 0, 1 and 3 days after culturing on culture dishes.
Project description:We undertook mRNA microarray and gene ontology analyses to screen out substrate stiffness-dependent genes. Total mRNA were extracted from E17 cortical neurons grown on soft or stiff substrates at 5 or 16 hr time points. We identified 114 differentially-expressed mRNA transcripts in cells grown on 0.1 kPa and 20 kPa gels at the 5 hr time-point. Among them, 66 were upregulated in 0.1 kPa gel cultures and the remainder were downregulated (compared to cells grown on stiffer substrates). The expressions of three endocytic genes (Cltc, Dab2, and Myo6) and four adhesion genes(Vcl, Robo2, Nrcam, and Cad11) were confirmed by QGP and smRNA FISH.