The effect of 70% hepatectomy on G-MDSCs transcription profile at different time points
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ABSTRACT: Liver regeneration depends on sequential activation of pathways and cells involving the remaining organ in recovery of mass. Proliferation of parenchyma is dependent on angiogenesis. Understanding liver regeneration-associated neovascularization may be useful for development of clinical interventions. Myeloid-derived suppressor cells (MDSCs) promote tumor angiogenesis and play a role in developmental processes that necessitate rapid vascularization. We therefore hypothesized that the MDSCs could play a role in liver regeneration. Following partial hepatectomy, MDSCs were enriched within regenerating livers, and their depletion led to increased liver injury and postoperative mortality, reduced liver weights, decreased hepatic vascularization, reduced hepatocyte hypertrophy and proliferation, and aberrant liver function. Gene expression profiling of regenerating liver-derived MDSCs demonstrated a large-scale transcriptional response involving key pathways related to angiogenesis. Functionally, enhanced reactive oxygen species production and angiogenic capacities of regenerating liver-derived MDSCs were confirmed. A comparative analysis revealed that the transcriptional response of MDSCs during liver regeneration resembled that of peripheral blood MDSCs during progression of abdominal tumors, suggesting a common MDSC gene expression profile promoting angiogenesis. In summary, our study shows that MDSCs contribute to early stages of liver regeneration possibly by exerting proangiogenic functions using a unique transcriptional program.
Project description:Liver regeneration following resection is a complex process relying on coordinated pathways and cell types in the remnant organ. Myeloid-Derived Suppressor Cells (MDSCs) have a role in liver regeneration-related angiogenesis but their influence on hepatocyte proliferation and immune modulation during liver regeneration is unclear. We examined the transcriptional response of regenerating liver hepatocytes after major resection in mice with CD11b+Ly6G+ MDSCs (G-MDSCs) depletion using RNA sequencing. Global gene expression profiling of regenerating hepatocytes upon G-MDSC depletion revealed disrupted transcriptional progression from day one to day two after major liver resection. Key genes and pathways related to hepatocyte proliferation and immune response were differentially expressed upon MDSC depletion. This study provides evidence that MDSCs contribute to early liver regeneration by promoting hepatocyte proliferation and modulating the intra-liver immune response. These findings illuminate the multifaceted role of MDSCs in liver regeneration.
Project description:The liver is the only organ in mammals, which fully regenerates after injury. To identify novel regulators of liver regeneration, we performed quantitative large-scale proteomics analysis of subcellular fractions from normal versus regenerating mouse liver. Proteins of the ubiquitin-proteasome pathway were rapidly regulated by partial hepatectomy, with the ubiquitin ligase Nedd4-1 being among the top hits. Knock-down of Nedd4-1 in hepatocytes in vivo through nanoparticle-mediated delivery of siRNA caused severe liver damage after partial hepatectomy and impaired regeneration, resulting in liver failure. Mechanistically, we demonstrate that Nedd4-1 is required for efficient activation of Erk1/2 signaling by receptor tyrosine kinases involved in liver regeneration through inhibition of receptor internalization, thus controlling a major pro-mitogenic and cytoprotective signaling pathway in the regenerating liver. These results highlight the power of large-scale proteomics to identify key players in liver regeneration and the importance of posttranslational regulation of growth factor signaling in this process.
Project description:Glioblastoma multiforme (GBM) is characterized by the close relationship of glioma stem cells (GSC) with aberrant vascularization. It has been established that GSC-derived extracellular vesicles (GSC-EVs) and their cargoes are proangiogenic in vitro. To elucidate gene regulatory mechanisms of neovascularization both in vitro and in vivo, we performed RNA-seq and DNA methylation profiling of the response of human brain endothelial cells to GSC-EVs as well as histoepigenetic analysis of GBM molecular profiles in the TCGA collection. The gene regulatory responses showed a footprint of post-transcriptional gene silencing by EV-derived miRNAs. Remarkably, EVs and normal vascular growth factors stimulated highly distinct gene regulatory responses, both converging on angiogenesis, providing exciting new insight into targetable angiogenic signaling in GBM.
Project description:Glioblastoma multiforme (GBM) is characterized by the close relationship of glioma stem cells (GSC) with aberrant vascularization. It has been established that GSC-derived extracellular vesicles (GSC-EVs) and their cargoes are proangiogenic in vitro. To elucidate gene regulatory mechanisms of neovascularization both in vitro and in vivo, we performed RNA-seq and DNA methylation profiling of the response of human brain endothelial cells to GSC-EVs as well as histoepigenetic analysis of GBM molecular profiles in the TCGA collection. The gene regulatory responses showed a footprint of post-transcriptional gene silencing by EV-derived miRNAs. Remarkably, EVs and normal vascular growth factors stimulated highly distinct gene regulatory responses, both converging on angiogenesis, providing exciting new insight into targetable angiogenic signaling in GBM.
Project description:Glioblastoma multiforme (GBM) is characterized by the close relationship of glioma stem cells (GSC) with aberrant vascularization. It has been established that GSC-derived extracellular vesicles (GSC-EVs) and their cargoes are proangiogenic in vitro. To elucidate gene regulatory mechanisms of neovascularization both in vitro and in vivo, we performed RNA-seq and DNA methylation profiling of the response of human brain endothelial cells to GSC-EVs as well as histoepigenetic analysis of GBM molecular profiles in the TCGA collection. The gene regulatory responses showed a footprint of post-transcriptional gene silencing by EV-derived miRNAs. Remarkably, EVs and normal vascular growth factors stimulated highly distinct gene regulatory responses, both converging on angiogenesis, providing exciting new insight into targetable angiogenic signaling in GBM.
Project description:In this work, we applied single-cell transcriptome sequencing on primary human liver tissue samples to study cellular processes underlying human liver regeneration. In order to study regeneration-specific cellular processes we obtained primary healthy liver tissue samples and liver tissue samples from patients that underwent a preoperative medical procedure called portal vein embolization (PVE). This medical treatment is performed to enlarge part of the liver such that a diseased portion can be removed avoiding liver insufficiency and thus we used post-PVE-derived tissues as a model to study liver regeneration in humans. This paradigm enabled us to catalog cell states related to tissue structure in two important and physiologically relevant conditions: hypertrophy and atrophy. In addition, we overcame technical challenges and provided novel protocols and pipelines for generating high quality liver cell atlases from frozen specimens showing consistency in results between fresh and frozen tissue datasets. Moreover, we established tissue-scale iterative indirect immunofluorescence imaging to enable high-dimensional spatial analysis of perivascular microenvironments and uncover cellular and histological alterations to regenerating liver lobules.
Project description:We examined uninjured and regenerating axolotl salamander retinas, including their transcriptional profile. We report that at 27 days after a retinectomy (early-mid regeneration), regenerating axolotl retinas exhibit downregulation of genes associated with neuronal networks but upregulation of genes associated with angiogenesis and the extracellular matrix. We also report differential expression of two Notch pathway effector genes, Hes1 and Hes5.
Project description:This study aimed to improve our understanding of the mechanisms of liver regeneration in sharks and to identify the microRNAs that participate in liver regeneration and other liver-related diseases. To this end, normal and regenerating liver tissues from C. plagiosum were harvested 0, 3, 6, 12 and 24 h after partial hepatectomy (PH) and were sequenced using the Illumina/Solexa platform. In total, 309 known microRNAs and 590 novel microRNAs were identified in C. plagiosum. There were 368 microRNAs differentially expressed between the normal and regenerating livers. Using target prediction and GO analysis, most of the differentially expressed microRNAs were assigned to functional categories that may be involved in regulating liver regeneration, such as cell proliferation, differentiation and apoptosis. Additionally, this study adds several novel microRNAs to the database, which will help identify microRNAs in other genetically related species and provides a starting point for future studies aimed at understanding the roles of microRNAs in liver regeneration and other liver diseases.
Project description:Autonomic nervous system is widely distributed in liver, and some reserchers have found that disruppted autonomic nerves will delay liver regeneration. We used microarrays to further highlight the regulatory role of autonomic nervous system in liver regeneration at gene transcription level. Surgical operations of rat partial hepatectomy (PH) and its operation control (OC), sympathectomy combining partial hepatectomy (SPH), vagotomy combining partial hepatectomy (VPH), and total liver denervation combining partial hepatectomy (TDPH) were performed, and the expression profiles of regenerating liver at 2h were detected using Rat Genome 230 2.0 array. Then the significantly changed genes related to liver regeneration (LR)-, injury-, splanchnic nerve-LR-, vagal nerve-LR-, and autonomic nerve-LR-related genes were identified, respectively. The relevance of gene expression profiles and biological processes was analyzed by bioinformatics and systems biology.
Project description:Myeloid-derived suppressor cells (MDSCs) potently suppress the anti-tumor immune responses and also orchestrate the tumor microenvironment that favors tumor angiogenesis and metastasis. The immunosuppressive activity of MDSCs has been extensively investigated, however the molecular networks regulating the non-immunological functions of tumor-expanded MDSCs, are largely unknown. In this study, we identified microRNA-494 (miR-494), whose expression was dramatically induced by tumor-derived factors (TDFs), as an essential player, in regulating the non-immunological activity of MDSCs by targeting PTEN and activating the Akt pathway. TGF-beta 1 was found to be a main tumor-derived factor responsible for the up-regulation of miR-494 in MDSCs. Expression of miR-494 not only enhanced CXCR4-mediated MDSC chemotaxis but also altered the intrinsic apoptotic/survival signal by targeting PTEN, thus contributing to the accumulation of MDSCs in tumor tissues. Consequently, down-regulation of PTEN resulted in increased activity of the Akt pathway and the subsequent up-regulation of matrix metalloproteinases (MMPs) for facilitating tumor cell invasion and metastasis. Knock down of miR-494 significantly reversed the activity of MDSCs and inhibited the tumor growth and metastasis of 4T1 murine breast cancer in vivo. Collectively, our findings reveal that TGF-beta 1-induced miR-494 expression in MDSCs plays a critical role in the molecular events governing the accumulation and non-immunological functions of tumor-expanded MDSCs, and might be identified as a potential target in cancer therapy. BALB/c mice (female, 6- to 8-wk-old) were injected subcutaneously in the mammary fat pad with 100,000 4T1 tumor cells. Three weeks later, tumor-bearing animals were used for the indicated studies. Gr-1+ CD11b+ cells were isolated by immunomagnetic selection from the bone marrow of 4T1 tumor-bearing mice (n=3) and tumor-free BALB/c mice (n=3), then the miRNA expression profile were analyzed using miRCURY LNAM-bM-^DM-" microRNA Arrays.