Project description:Mice with MUTYH-null allele (Mutyh+/-, Mutyh-/-) were fed a high-fat/high-cholesterol (HFHC) diet or HFHC + high iron diet. The incidence of liver tumors and histological features of the liver were compared. We used microarray to examine the gene expression patterns associated with hepatocarcinogenesis in our model.
Project description:Non-alcoholic fatty liver disease (NAFLD) is characterized by a series of pathological changes that can progress from simple fatty liver disease to non-alcoholic steatohepatitis (NASH). The objective of this study is to describe changes in global gene expression associated with the progression of NAFLD. This study is focused on the expression levels of genes responsible for the absorption, distribution, metabolism and excretion (ADME) of drugs. Differential gene expression between three clinically defined pathological groups; normal, steatosis and NASH was analyzed. The samples were diagnosed as normal, steatotic, NASH with fatty liver (NASH fatty) and NASH without fatty liver (NASH NF). Genome-wide mRNA levels in samples of human liver tissue were assayed with Affymetrix GeneChipM-. Human 1.0ST arrays
Project description:Oxidative stress is a major risk factor for Alzheimer’s disease (AD), which is characterized by brain atrophy, amyloid plaques, neurofibrillary tangles, and loss of neurons. 8-Oxoguanine, a major oxidatively generated nucleobase highly accumulated in the AD brain, is known to cause neurodegeneration. In mammalian cells, several enzymes play essential roles in minimizing the 8-oxoguanine accumulation in DNA. MUTYH with adenine DNA glycosylase activity excises adenine inserted opposite 8-oxoguanine in DNA. MUTYH is reported to actively contribute to the neurodegenerative process in Parkinson and Huntington diseases and some mouse models of neurodegenerative diseases by accelerating neuronal dysfunction and microgliosis under oxidative conditions; however, whether or not MUTYH is involved in AD pathogenesis remains unclear. In the present study, we examined the contribution of MUTYH to the AD pathogenesis. Using postmortem human brains, we showed that various types of MUTYH transcripts and proteins are expressed in most hippocampal neurons and glia in both non-AD and AD brains. We further introduced MUTYH deficiency into AppNL-G-F/NL-G-F knock-in AD model mice, which produce humanized toxic amyloid-β without the overexpression of APP protein, and investigated the effects of MUTYH deficiency on the behavior, pathology, gene expression, and neurogenesis. MUTYH deficiency improved memory impairment in AppNL-G-F/NL-G-F mice, accompanied by reduced microgliosis. Gene expression profiling strongly suggested that MUTYH is involved in the microglial response pathways under AD pathology and contributes to the phagocytic activity of disease-associated microglia. We also found that MUTYH deficiency ameliorates impaired neurogenesis in the hippocampus, thus improving memory impairment. In conclusion, we propose that MUTYH, which is expressed in the hippocampus of AD patients as well as non-AD subjects, actively contributes to memory impairment by inducing microgliosis with poor neurogenesis in the preclinical AD phase and that MUTYH is a novel therapeutic target for AD, as its deficiency is highly beneficial for ameliorating AD pathogenesis.
Project description:Hepatocellular carcinoma (HCC), which accounts for 90% of all primary livers tumors, is the fourth most common cancer in the world. The development of HCC is a long-term and complex process, and uncovering the molecular mechanisms associated with HCC development is critical for the disease diagnosis, prevention, and treatment. Exploring these mechanisms using human HCC samples is desirable, but frequently impractical, with a number of limitations and shortcomings. The STAMTM (Stelic Institute & Co, Tokyo, Japan) mouse model of NASH-associated liver carcinogenesis is considered a useful and relevant model for investigating the molecular pathogenesis of NASH-derived HCC. This model resembles the human HCC development associated with progression from simple steatosis to NASH, fibrosis, and HCC. In the present study, by using high-throughput whole genome microarrays (SurePrint G3 Mouse Gene Expression v2, 8x60K; Agilent Technologies, Santa Clara, CA), we examined the transcriptomic profiles in the livers of STAMTM mice at different stages of liver carcinogenesis, including steatosis (6 week time interval), NASH (8 weeks), fibrotic stage (12 weeks), and in full-fledged HCC (20 weeks). The results of microarray analyses showed significant progressive changes in hepatic gene expression during the development of HCC. A total of 970, 1462, 2742, and 2857 of differentially expressed genes were identified in the livers at 6, 8, 12, and 20 weeks, respectively. Detailed analysis of these differentially expressed genes will benefit the understanding of the underlying mechanisms of non-alcoholic fatty liver disease-derived HCC. Transcriptomic profile in the liver of STAM mice at 6 weeks (steatosis; n=3), 8 weeks (steatohepatitis; n=3) 12 weeks (fibrosis; n=4) and 20 weeks (HCC-stage tumor tissue, n=4) weeks. Age-matched control samples were also analyzed.
Project description:Non-alcoholic steatohepatitis (NASH)-related HCC is associated with oxidative stress. However, the mechanisms underlying the development of NASH-related HCC is unclear. MUTYH is one of the enzymes that is involved in repair of oxidative DNA damage. The aim of this study was to investigate the association between MUTYH and NASH-related hepatocarcinogenesis. MUTYH wild-type (Mutyh+/+), heterozygous (Mutyh+/-), and MUTYH-null (Mutyh-/-) mice were fed a high-fat high-cholesterol (HFHC) diet or HFHC + high iron diet (20 mice per group) for 9 months. Five of 20 Mutyh-/- mice fed an HFHC + high iron diet developed liver tumors, and they developed more liver tumors than other groups (especially vs. Mutyh+/+ fed an HFHC diet, P = 0.0168). Immunohistochemical analysis revealed significantly higher accumulation of oxidative stress markers in mice fed an HFHC + high iron diet. The gene expression profiles in the non-tumorous hepatic tissues were compared between wild-type mice that developed no liver tumors and MUTYH-null mice that developed liver tumors. Gene Set Enrichment Analysis identified the involvement of the Wnt/β-catenin signaling pathway and increased expression of c-Myc in MUTYH-null liver. These findings suggest that MUTYH deficiency is associated with hepatocarcinogenesis in patients with NASH with hepatic iron accumulation.
Project description:Non-alcoholic fatty liver disease/steatohepatitis (NAFLD/NASH) is a significant risk factor for hepatocellular carcinoma (HCC). However, a preclinical model of progressive NAFLD/NASH is largely lacking. Here, we report that mice with hepatocyte-specific deletion of Tid1, encoding a mitochondrial cochaperone, tended to develop NASH-dependent HCC. Mice with hepatic Tid1 deficiency showed impairing mitochondrial function and causing fatty acid metabolic dysregulation; meanwhile, sequentially developed fatty liver, NASH, and cirrhosis/HCC in a diethylnitrosamine (DEN) induced oxidative environment. The pathological signatures of human NASH, including cholesterol accumulation and activation of inflammatory and apoptotic signaling pathways, are also present in these mice. Clinically, low Tid1 expression was associated with unfavorable prognosis in patients with HCC. Empirically, hepatic Tid1 deficiency directly disrupts entire mitochondria that play a key role in the NASH-dependent HCC development. Overall, we established a new mouse model that develops NASH-dependent HCC and provides a promising approach to improve the treatment.
Project description:Non-alcoholic steatohepatitis (NASH) is the most significant cause of chronic liver disease worldwide, with limited therapeutic options. In this experiment, a choline-deficient amino acid-defined high fat diet (CDAHFD) were used to construct a mouse NASH model. After 16 weeks of CDAHFD diets, liver samples were collected. We want to further confirm that the elevated EFHD2 is specifically expressed in infiltrated macrophages/monocytes in NASH.
Project description:Oxidative DNA damage has been associated with cognitive decline. The Ogg1 and Mutyh DNA glycosylases cooperate to prevent mutations caused by 8-oxoG, a major premutagenic oxidative DNA base lesion. Here, we have examined behavior and cognitive function in mice deficient of these glycosylases. We found that Ogg1-/-Mutyh-/- mice were more active and less anxious and that their learning ability was impaired. In contrast, Mutyh-/- mice showed moderately improved memory compared to WT. There was no change in genomic 8-oxoG levels, suggesting that Ogg1 and Mutyh play minor roles in global repair in adult brain. Notably, transcriptome analysis of hippocampus revealed that differentially expressed genes in the mutant mice belong to pathways known to be involved in anxiety and cognitive function. Thus, beyond their involvement in DNA repair, Ogg1 and Mutyh modulate cognitive function and behavior, and related hippocampal gene expression, suggesting a novel role for 8-oxoG in regulating adaptive behavior.
Project description:RNAseq analysis that will help to define 1) the circadian dysfunction induced liver transcriptome that drives fatty liver disease induced hepatocarcinogenesis in a humanized mouse model; 2) the currently unknown circadian profile of NASH and HCC gene signatures specifically associated with human hepatocytes and liver or tumor microenvironment. These gene signatures will significantly advance our understanding of the mechanism of spontaneous HCC and have important preclinic values for developing novel therapeutic strategies for prevention and treatment of HCC in humans.