Project description:Activated primary murine hepatic stellate cells were transfected with siRNA targeting Caveolin-1 directly after attachment (o/n). Experiment was performed in triplicate using primary cells from 3 donor mice.
Project description:Endoglin is a transmembrane receptor able to bind several members of the transforming growth factor-beta superfamliy. We used a siRNA-mediated knock down approach to analyse the function of Endoglin in hepatic stellate cells (HSC). We found that the targeted disruption is associated with significant changes in gene expression resulting in cellular changes that prolongated cellular activation, morphological maturation, transdifferentiation, expression of basement and fibrillar extracellular matrix proteins. In addition, the lack of Endoglin resulted in rearrangements of cytoskeletal organization. Keywords: gene function analysis, siRNA, gene knock down
Project description:The p53 protein is a cell-autonomous tumor suppressor that restricts malignant transformation by triggering cell cycle exit or apoptosis. p53 also promotes cellular senescence, a program that triggers a stable cell cycle arrest and can modify the tissue microenvironment through its effect on cell membrane and secretory proteins. Here we show that specific ablation of p53 in hepatic stellate cells, which undergo a process of proliferation and senescence in the fibrogenic response to liver damage, enhances liver cirrhosis, reduces survival and increases the malignant transformation of adjacent epithelial cells into hepatocellular carcinoma. This p53-dependent senescence program involves the release of secreted proteins which skew macrophages into a tumor-inhibiting M1-state that can eliminate senescent stellate cells. In contrast, p53-deficient stellate cells secrete factors that promote M2 polarization, which is pro-tumorigenic. Our study reveals that p53 can exert a non-cell-autonomous tumor suppressor response and suggests that this occurs, in part, by its ability to influence macrophage polarization. We used microarrays to detail the global programme of gene expression underlying p53-dependent senescent and identified distinct classes of up-regulated or down-regulated genes during this process. Proliferating and senescent stellate cell pellets were collected RNA extraction and hybridization on Affymetrix microarrays.
Project description:Gene expression of mouse hepatic stellate cells was characterized under the following conditions: Quiescent (isolated from normal mouse liver) and reverted (isolated from mouse liver treated with 4 injections of carbontetrachloride followed by 45 day rest period) Affymetrix Mouse 1.0ST gene expression measurements were used to characterize the transcriptomic basis in quiescent hepatic stellate cells, isolated from normal liver, and reverted hepatic stellate cells, isolated from liver treated with 4 injections of CCl4 followed by a 45 day rest period. Gene expression of mouse hepatic stellate cells was characterized under the following conditions: A. Quiescent control hepatic stellate cells (n=4). B. Reverted hepatic stellate cells (n=4).
Project description:The p53 protein is a cell-autonomous tumor suppressor that restricts malignant transformation by triggering cell cycle exit or apoptosis. p53 also promotes cellular senescence, a program that triggers a stable cell cycle arrest and can modify the tissue microenvironment through its effect on cell membrane and secretory proteins. Here we show that specific ablation of p53 in hepatic stellate cells, which undergo a process of proliferation and senescence in the fibrogenic response to liver damage, enhances liver cirrhosis, reduces survival and increases the malignant transformation of adjacent epithelial cells into hepatocellular carcinoma. This p53-dependent senescence program involves the release of secreted proteins which skew macrophages into a tumor-inhibiting M1-state that can eliminate senescent stellate cells. In contrast, p53-deficient stellate cells secrete factors that promote M2 polarization, which is pro-tumorigenic. Our study reveals that p53 can exert a non-cell-autonomous tumor suppressor response and suggests that this occurs, in part, by its ability to influence macrophage polarization. We used microarrays to detail the global programme of gene expression underlying p53-dependent senescent and identified distinct classes of up-regulated or down-regulated genes during this process.
Project description:Background & Aims: Rapid induction of beta-PDGF receptor (beta-PDGFR) is a core feature of hepatic stellate cell activation, the hallmark of liver fibrogenesis. However, biological consequences of the induction are not well characterized. We aimed to determine the involvement of beta-PDGFR-mediated molecular pathway activation on hepatic stellate cells in liver injury, fibrogenesis, and carcinogenesis in vivo. Methods: Loss and constitutive activation of beta-PDGFR were assessed in mouse models with either a stellate cell-specific beta-PDGFR knockout or the expression of an autoactivating mutation respectively. Liver injury and fibrosis were induced in two mechanistically distinct models: carbontetrachloride (CCl4) treatment and ligation of the common bile duct. Hepatocarcinogenesis with underlying liver injury/fibrosis was assessed by a single dose of diethylnitrosamine (DEN) followed by repeated injections of CCl4. Genome-wide expression profiling was performed isolated stellate cells from these models to determine deregulated pathways. Results: Depletion of beta-PDGFR in hepatic stellate cells led to decreased histological liver injury, serum transaminases, collagen alpha 1(I) and alpha smooth muscle actin expression, and collagen deposition. Stellate cell proliferation was significantly reduced after acute hepatic injury in vivo. In contrast, autoactivation of beta-PDGFR in stellate cells accelerated liver fibrosis, most prominently after 6 weeks of CCl4 induced injury. There was no difference in development of DEN-induced pre-neoplastic loci according to the status of beta-PDGFR. Conclusions: Depletion of beta-PDGFR in hepatic stellate cells attenuated the development of liver injury, fibrosis, and stellate cell proliferation in multiple animal models, whereas the constitutive activation of beta-PDGFR enhanced fibrosis. However, manipulation of beta-PDGFR alone did not reduce development of dysplastic nodules. These findings indicate that titration of receptor beta-PDGFR expression on stellate cells parallels fibrosis and injury, but may not impact the development of hepatic neoplasia alone. Hepatic stellate cells were isolated from liver of beta-PDGFR-wild-type or knockout mice, and treated with beta-PDGF ligand or vehicle control.
Project description:Analysis of hepatic stellate cells isoltaed from wild-type, TLR4-/-, and CD44-/- mice. TLR4 and CD44 are major hyaluronic acid receptors. Results provide insight into the effects of TLR4 and CD44 loss in hepatic stellate cells.
Project description:Unveiling the regulatory pathways maintaining hepatic stellate cells (HSC) in a quiescent (q) phenotype is essential to develop new therapeutic strategies to treat fibrogenic diseases. To uncover the miRNA-mRNAs regulatory interactions in qHSCs, HSCs were FACS-sorted from healthy livers and activated HSCs were generated in vitro. MiRNA Taqman array analysis showed HSCs expressed a low number of miRNA, from which 46 were down-regulated and 212 up-regulated upon activation. Computational integration of miRNA and gene expression profiles revealed that 66% of qHSCs miRNAs correlated with more than 6 altered targeted mRNAs (17,28±10,7 targets/miRNA), whereas aHSC-associated miRNAs had an average of 1,49 targeted genes. Interestingly, interaction networks generated by miRNA-targeted genes in qHSCs were associated with key HSCs activation processes. Next, selected miRNAs were validated in healthy and cirrhotic human livers and miR-192 was chosen for functional analysis. Down-regulation of miR-192 in HSC was found to be an early event during fibrosis progression in mouse models of liver injury. Moreover, mimic assays for miR-192 in HSCs revealed its role in HSC activation, proliferation and migration. Together, these results uncover the importance of miRNAs in the maintenance of qHSC phenotype and form the basis for understanding the regulatory networks in HSCs. Transcriptomic profile derived from four quiescent hepatic stellate (QHSC), four activated hepatic stellate (AHSC), three liver sinusoidal endothelial (LSEC) and two hepatocytes cells (HEP).