Project description:Liver sinusoidal endothelial cells (LSEC) represent a unique, organ-specific type of discontinuous endothelial cells. LSEC instruct the hepatic vascular niche by paracrine-acting angiocrine factors. Recently, we have shown that LSEC-specific transcriptional regulator GATA4 induces expression of BMP2 in cultured endothelial cells (EC) in vitro. Furthermore, angiocrine Bmp2 signaling in the liver in vivo was demonstrated to control iron homeostasis. Here, we investigated GATA4-dependent autocrine BMP2 signaling in endothelial cells by gene expression profiling. GATA4 induced a large cluster of inflammatory endothelial response genes in cultured EC, which is similar to previously identified virus-induced and interferon-associated responses. Treating the cells with the BMP2 inhibitor Noggin counter-regulated the GATA4-dependent inflammatory phenotype of EC, indicating that BMP2 is indeed the major driver. In contrast to continuous EC, LSEC were less prone to activation by BMP2. Notably, GATA4-dependent induction of the inflammatory EC response gene cluster was attenuated by over-expression of the LSEC-specific transcriptional modifier LMO3 while hepatocyte activation was fully preserved, indicating conserved BMP2 synthesis. In summary, our data suggest that transcriptional counter-regulation by GATA4 and LMO3 in LSEC prevents autocrine induction of an inflammatory phenotype, while maintaining angiocrine BMP2-mediated cell communication in the liver vascular niche.
Project description:Liver sinusoidal endothelial cells (LSEC) represent a unique, organ-specific type of discontinuous endothelial cells. LSEC instruct the hepatic vascular niche by paracrine-acting angiocrine factors. Recently, we have shown that LSEC-specific transcriptional regulator GATA4 induces expression of BMP2 in cultured endothelial cells (EC) in vitro. Furthermore, angiocrine Bmp2 signaling in the liver in vivo was demonstrated to control iron homeostasis. Here, we investigated GATA4-dependent autocrine BMP2 signaling in endothelial cells by gene expression profiling. GATA4 induced a large cluster of inflammatory endothelial response genes in cultured EC, which is similar to previously identified virus-induced and interferon-associated responses. Treating the cells with the BMP2 inhibitor Noggin counter-regulated the GATA4-dependent inflammatory phenotype of EC, indicating that BMP2 is indeed the major driver. In contrast to continuous EC, LSEC were less prone to activation by BMP2. Notably, GATA4-dependent induction of the inflammatory EC response gene cluster was attenuated by over-expression of the LSEC-specific transcriptional modifier LMO3 while hepatocyte activation was fully preserved, indicating conserved BMP2 synthesis. In summary, our data suggest that transcriptional counter-regulation by GATA4 and LMO3 in LSEC prevents autocrine induction of an inflammatory phenotype, while maintaining angiocrine BMP2-mediated cell communication in the liver vascular niche.
Project description:Gata4 and LMO3 balance angiocrine signaling and autocrine inflammatory activation by BMP2 in liver sinusoidal endothelial cells [HLSEC]
Project description:Angiocrine signaling by liver sinusoidal endothelial cells (LSEC) regulates liver functions such as liver growth, metabolic maturation, and regeneration. Recently, we identified GATA4 as the master regulator of LSEC specification during development. Here, we studied endothelial GATA4 in the adult liver and in hepatic disease pathogenesis. We generated adult Clec4g-icretg/0xGata4fl/fl (Gata4LSEC KO) mice with deficiency of Gata4 in LSEC. Livers were analyzed by histology, electron microscopy, immunohistochemistry/immunofluorescence, in-situ hybridization, and by expression profiling and ATAC-sequencing of isolated LSEC. For liver regeneration, partial hepatectomy was performed. As models of liver fibrosis, CDAA diet and chronic CCl4 exposure were applied. Human single cell RNAseq data sets were analyzed for endothelial alterations in healthy and cirrhotic livers. Genetic Gata4 deficiency in LSEC in adult mice caused perisinusoidal liver fibrosis, hepatopathy and impaired liver regeneration. Sinusoidal capillarization and LSEC-to-continuous endothelial transdifferentiation were accompanied by a profibrotic angiocrine switch including de novo endothelial expression of hepatic stellate cell-activating cytokine PDGFB. Increased chromatin accessibility and amplification by activated Myc mediated angiocrine PDGFB expression. In CDAA diet-induced perisinusoidal liver fibrosis, LSEC showed repression of GATA4, activation of MYC and the profibrotic angiocrine switch already detected in Gata4LSEC KO mice. Comparison of CDAA-fed Gata4LSEC KO and control mice demonstrated that endothelial Gata4 indeed protects from dietary-induced perisinusoidal liver fibrosis. In human cirrhotic livers, Gata4-positive LSEC and endothelial Gata4 target genes were reduced, while non-LSEC endothelial cells and Myc target genes including PDGFB were enriched. Endothelial GATA4 protects from perisinusoidal liver fibrosis by repressing MYC activation and profibrotic angiocrine signaling on the chromatin level. Therapies targeting the GATA4/MYC/PDGFB/PDGFRβ axis offer a promising strategy for the prevention and treatment of liver fibrosis.
Project description:Angiocrine signaling by liver sinusoidal endothelial cells (LSEC) regulates liver functions such as liver growth, metabolic maturation, and regeneration. Recently, we identified GATA4 as the master regulator of LSEC specification during development. Here, we studied endothelial GATA4 in the adult liver and in hepatic disease pathogenesis. We generated adult Clec4g-icretg/0xGata4fl/fl (Gata4LSEC KO) mice with deficiency of Gata4 in LSEC. Livers were analyzed by histology, electron microscopy, immunohistochemistry/immunofluorescence, in-situ hybridization, and by expression profiling and ATAC-sequencing of isolated LSEC. For liver regeneration, partial hepatectomy was performed. As models of liver fibrosis, CDAA diet and chronic CCl4 exposure were applied. Human single cell RNAseq data sets were analyzed for endothelial alterations in healthy and cirrhotic livers. Genetic Gata4 deficiency in LSEC in adult mice caused perisinusoidal liver fibrosis, hepatopathy and impaired liver regeneration. Sinusoidal capillarization and LSEC-to-continuous endothelial transdifferentiation were accompanied by a profibrotic angiocrine switch including de novo endothelial expression of hepatic stellate cell-activating cytokine PDGFB. Increased chromatin accessibility and amplification by activated Myc mediated angiocrine PDGFB expression. In CDAA diet-induced perisinusoidal liver fibrosis, LSEC showed repression of GATA4, activation of MYC and the profibrotic angiocrine switch already detected in Gata4LSEC KO mice. Comparison of CDAA-fed Gata4LSEC KO and control mice demonstrated that endothelial Gata4 indeed protects from dietary-induced perisinusoidal liver fibrosis. In human cirrhotic livers, Gata4-positive LSEC and endothelial Gata4 target genes were reduced, while non-LSEC endothelial cells and Myc target genes including PDGFB were enriched. Endothelial GATA4 protects from perisinusoidal liver fibrosis by repressing MYC activation and profibrotic angiocrine signaling on the chromatin level. Therapies targeting the GATA4/MYC/PDGFB/PDGFRβ axis offer a promising strategy for the prevention and treatment of liver fibrosis.
Project description:Microvascular endothelial cells (EC) display a high degree of phenotypic and functional heterogeneity among different organs. Organ-specific EC control their tissue microenvironment by angiocrine factors in health and disease. Liver sinusoidal EC (LSEC) are uniquely differentiated to fulfil important organ-specific functions in development, under homeostatic conditions, and in regeneration and liver pathology. Recently, Bmp2 has been identified by us as an organ-specific angiokine derived from LSEC. To study angiocrine Bmp2 signaling in the liver, we conditionally deleted Bmp2 in LSEC using EC subtype-specific Stab2-Cre mice. Genetic inactivation of hepatic angiocrine Bmp2 signaling in Stab2-Cre;Bmp2fl/fl (Bmp2LSECKO) mice caused massive iron overload in the liver, and increased serum iron levels and iron deposition in several organs similar to classic hereditary hemochromatosis. Iron overload was mediated by decreased hepatic expression of hepcidin, a key regulator of iron homeostasis. Thus, angiocrine Bmp2 signaling within the hepatic vascular niche represents a constitutive pathway indispensable for iron homeostasis in vivo that is non-redundant with Bmp6. Notably, we demonstrate that organ-specific angiocrine signaling is essential not only for the homeostasis of the respective organ, but also for the homeostasis of the whole organism.
Project description:The aim of this study was to induce cardiomyogenic conversion of Human Umbilical Vein Endothelial Cells (HUVEC ) by triggering ectopic expression of the cardiac transcription factors Nkx2.5 and GATA4. Cells were cultured without cell myocardial co-culture system and transduced with lentivirus containing coding sequence of Nkx2.5, GATA4 or GFP as control. Cells were cultured in the EBM-2/ EGM-2 medium, 12 days before microarray analysis. We report in this study that over-expression of NKX2.5 and GATA4 in HUVECs stimulates the expression of some specific genes important in the cardiomyogenic differentiation process, leading to partial switch of these cells from the endothelial to the myocardial course. 12 arrays were analysed. Three competitive hybridizations to the arrays were performed in duplicate using each time, two dye-swap following this experimental design: AWA065 : CY5 (HUVEC+NKX2,5) / CY3 (HUVEC) AWA067 : CY5 (HUVEC) / CY3 (HUVEC+NKX2,5) AWA075 : CY5 (HUVEC+NKX2,5) / CY3 (HUVEC) AWA076 : CY5 (HUVEC) / CY3 (HUVEC+NKX2,5) AWA068 : CY5 ((HUVEC) / CY3 (HUVEC+GATA4) AWA070 : CY5 (HUVEC+GATA4) / CY3 ((HUVEC) AWA073 : CY5 (HUVEC+GATA4) / CY3 ((HUVEC) AWA002 : CY5 ((HUVEC) / CY3 (HUVEC+GATA4) AWA066 : CY5 (HUVEC) / CY3 (HUVEC+NKX2.5+GATA4) AWA069 : CY5 (HUVEC+NKX2.5+GATA4) / CY3 (HUVEC) AWA071 : CY5 (HUVEC+NKX2.5+GATA4) / CY3 (HUVEC) AWA074 ; CY5 (HUVEC) / CY3 (HUVEC+NKX2.5+GATA4)
Project description:Liver sinusoidal endothelial cells (LSEC) are highly specialized within the hepatic vascular niche, controlling liver function and disease pathogenesis by angiocrine signaling. Recently, we identified GATA4 as a major transcription factor controlling LSEC development and protecting against liver fibrosis. As the transcription factor c-Maf was strongly downregulated in Gata4-deficient LSEC, we hypothesized that c-Maf might be an important downstream effector of GATA4 in LSEC differentiation and liver fibrogenesis. Clec4g-iCre/Maf fl/fl mice (Maf-LSEC-KO) mice with LSEC-specific Maf deficiency were generated and liver tissue was analyzed by histology, immunofluorescence, and in situ-hybridization at the age of three months. LSECs were isolated for RNA-, ATAC-seq, and single-cell RNA-seq (scRNA-seq) analysis. The expression of MAF and its targets were analyzed in published human scRNA-seq data. Endothelial Maf deficiency resulted in perisinusoidal liver fibrosis without affecting metabolic liver zonation, accompanied by a switch from sinusoidal to continuous endothelial differentiation. Furthermore, endothelial Maf deficiency caused hepatic endothelial proliferation and expression of profibrotic angiocrine factors such as Pdgfb, Igfbp5, Sparcl-1, and Flrt2. scRNA-seq revealed replacement of zonated LSEC subpopulations by capillarized, proliferative, sprouting and secretory endothelial cell subset promoting liver fibrogenesis and angiogenesis. This fundamental dysregulation of LSEC gene expression and differentiation was caused by changes in chromatin accessibility and transcription factor network alterations at promoter and enhancer regions following loss of Maf. Notably, endothelial MAF expression was also significantly reduced in human liver cirrhosis patients. Hepatic endothelial c-Maf protects against metabolic dysfunction-associated steatohepatitis-like liver fibrosis and regulates endothelial differentiation and zonation by controlling chromatin opening. Notably, our findings may open up new avenues to develop angiotargeted strategies for hepatic disease prevention and liver repair.
Project description:Liver sinusoidal endothelial cells (LSEC) are highly specialized within the hepatic vascular niche, controlling liver function and disease pathogenesis by angiocrine signaling. Recently, we identified GATA4 as a major transcription factor controlling LSEC development and protecting against liver fibrosis. As the transcription factor c-Maf was strongly downregulated in Gata4-deficient LSEC, we hypothesized that c-Maf might be an important downstream effector of GATA4 in LSEC differentiation and liver fibrogenesis. Clec4g-iCre/Maffl/fl mice (MafLSEC-KO) mice with LSEC-specific Maf deficiency were generated and liver tissue was analyzed by histology, immunofluorescence, and in situ-hybridization at the age of three months. LSECs were isolated for RNA-, ATAC-seq, and single-cell RNA-seq (scRNA-seq) analysis. The expression of MAF and its targets were analyzed in published human scRNA-seq data. Endothelial Maf deficiency resulted in perisinusoidal liver fibrosis without affecting metabolic liver zonation, accompanied by a switch from sinusoidal to continuous endothelial differentiation. Furthermore, endothelial Maf deficiency caused hepatic endothelial proliferation and expression of profibrotic angiocrine factors such as Pdgfb, Igfbp5, Sparcl-1, and Flrt2. scRNA-seq revealed replacement of zonated LSEC subpopulations by capillarized, proliferative, sprouting and secretory endothelial cell subsets promoting liver fibrogenesis and angiogenesis. This fundamental dysregulation of LSEC gene expression and differentiation was caused by changes in chromatin accessibility and transcription factor network alterations at promoter and enhancer regions following loss of Maf. Notably, endothelial MAF expression was also significantly reduced in human liver cirrhosis patients. Hepatic endothelial c-Maf protects against metabolic dysfunction-associated steatohepatitis-like liver fibrosis and regulates endothelial differentiation and zonation by controlling chromatin opening. Notably, our findings may open up new avenues to develop angiotargeted strategies for hepatic disease prevention and liver repair.