Nuclear polysaccharides maintain H3K9me3-heterochromatin and genomic stability
Ontology highlight
ABSTRACT:
ORGANISM(S): Mus Musculus
SUBMITTER: 
Shisheng Sun
PROVIDER: PXD072505 | iProX | Tue Dec 30 00:00:00 GMT 2025
REPOSITORIES: iProX
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Project description:Nuclear polysaccharides maintain H3K9me3-heterochromatin and genomic stability
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Project description:Colorectal cancer, one of the most frequent types of malignancy in the Western world, develops through a multi-step process. The main pathways establishing transformation of normal mucosa to invasive carcinoma include chromosomal instability (CIN), microsatellite instability (MSI) or epigenetic silencing through the CpG Island Methylator Phenotype (CIMP). These pathways have distinct clinical, pathological and genetic characteristics. In general, altered cell surface glycosylation has been linked to colorectal cancer progression, however the impact of MSI-specific pathways on the glycosylation machinery of MSI colon cancer cells has not been investigated yet. In a recent study (Patsos et al., 2009) we have shown that MSI-specific mutations induce marked alterations in cell surface glycosylation, indicating specific changes in the expression of glyco-genes. Therefore the purpose of our experiment is to define these changes by glyco-gene chip analysis.
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Project description:Although hepatitis B virus (HBV) has been established to cause hepatocellular carcinoma (HCC), the exact mechanism remains to be clarified. Type II ground glass hepatocytes (GGH) harboring the HBV pre-S2 mutant large surface protein have been recognized as morphologically distinct hallmark of HCC in advanced stages of chronic HBV infection. Considering its pre-neoplastic nature, we hypothesized that type II GGH may exhibit high genomic instability, which is important for the carcinogenic process in chronic HBV carriers. In this study we found that pre-S2 mutant LHBS directly interacted with importin 1, the key factor that recognizes cargos undergoing nuclear transportation mediated by the importin 1 associated nuclear pore complex (NPC). By interacting with importin 1, which inhibits its function as an NPC factor, pre-S2 mutant LHBS blocked nuclear transportation of an essential DNA repair and recombination factor Nijmegen breakage syndrome 1 (NBS1) upon DNA damage, thereby delaying formation of nuclear foci at the sites of DNA double strand breaks. Pre-S2 mutant LHBS was also found to block NBS1-mediated homologous recombination repair and induce multi-nucleation of cells. In addition, pre-S2 mutant LHBS transgenic mice showed genomic instability indicated by increased global gene copy number variations (CNV), which were significantly higher than those in hepatitis B virus X mice, indicating that pre-S2 mutant LHBS is the major viral oncoprotein inducing genomic instability in HBV-infected hepatocytes. Consistently, the human type II GGHs in HCC patients exhibited increased DNA double-strand breaks representing significant genomic instability. In conclusion, type II GGH harboring HBV pre-S2 mutant oncoprotein represents a high-risk marker for the loss of genome integrity in chronic HBV carriers and explains the complex chromosome changes in HCCs. Non-tumorous liver sections from four each the HBx and pre-S2 mutant LHBS transgenic mice and 3 double transgenic mice between 9 and 22 months old were examined for gene gain and loss.
2014-09-13 | E-GEOD-61378 | biostudies-arrayexpress
Project description:Although hepatitis B virus (HBV) has been established to cause hepatocellular carcinoma (HCC), the exact mechanism remains to be clarified. Type II ground glass hepatocytes (GGH) harboring the HBV pre-S2 mutant large surface protein have been recognized as morphologically distinct hallmark of HCC in advanced stages of chronic HBV infection. Considering its pre-neoplastic nature, we hypothesized that type II GGH may exhibit high genomic instability, which is important for the carcinogenic process in chronic HBV carriers. In this study we found that pre-S2 mutant LHBS directly interacted with importin 1, the key factor that recognizes cargos undergoing nuclear transportation mediated by the importin 1 associated nuclear pore complex (NPC). By interacting with importin 1, which inhibits its function as an NPC factor, pre-S2 mutant LHBS blocked nuclear transportation of an essential DNA repair and recombination factor Nijmegen breakage syndrome 1 (NBS1) upon DNA damage, thereby delaying formation of nuclear foci at the sites of DNA double strand breaks. Pre-S2 mutant LHBS was also found to block NBS1-mediated homologous recombination repair and induce multi-nucleation of cells. In addition, pre-S2 mutant LHBS transgenic mice showed genomic instability indicated by increased global gene copy number variations (CNV), which were significantly higher than those in hepatitis B virus X mice, indicating that pre-S2 mutant LHBS is the major viral oncoprotein inducing genomic instability in HBV-infected hepatocytes. Consistently, the human type II GGHs in HCC patients exhibited increased DNA double-strand breaks representing significant genomic instability. In conclusion, type II GGH harboring HBV pre-S2 mutant oncoprotein represents a high-risk marker for the loss of genome integrity in chronic HBV carriers and explains the complex chromosome changes in HCCs.
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