Project description:Abnormalities in hepatic lipid metabolism are believed to play a critical role in the etiology of nonalcoholic steatohepatitis (NASH). Monoacylglycerol acyltransferase (MGAT) enzymes convert monoacylglycerol to diacylglycerol, which is the penultimate step in one pathway for triacylglycerol (TAG) synthesis. Hepatic expression of Mogat1, which encodes an MGAT enzyme, is increased in the livers of mice with hepatic steatosis and knocking down Mogat1 improves insulin sensitivity, but whether increased MGAT activity plays a role in the etiology of NASH is unclear. To examine the effects of knocking down Mogat1 in the liver on the development of NASH, C57BL/6 mice were placed on a diet containing high levels of trans fatty acids, fructose, and cholesterol (HTF-C diet) or a low fat control diet for 4 weeks. Mice were then injected with antisense oligonucleotides (ASO) to knockdown Mogat1 or a scrambled ASO control for 12 weeks while remaining on diet. HTF-C diet caused glucose intolerance, hepatic steatosis, and induced hepatic gene expression markers of inflammation, macrophage infiltration, and stellate cell activation. Mogat1 ASO treatment, which suppressed Mogat1 expression in liver, attenuated weight gain, improved glucose tolerance, and decreased hepatic TAG content compared to control ASO-treated mice on HTF-C chow. However, Mogat1 ASO treatment did not reduce hepatic DAG, cholesterol, or free fatty acid content, improve histologic measures of liver injury, or reduce expression of markers of stellate cell activation, liver inflammation, and injury. In conclusion, inhibition of hepatic Mogat1 in HTF-C diet-fed mice improves glucose tolerance and hepatic TAG accumulation without attenuating liver inflammation and injury. Total RNA obtained from liver of 4 control vs. 4 Mogat1 ASO treated higf-fat diet (HFD) fed mice.
Project description:Abnormalities in hepatic lipid metabolism are believed to play a critical role in the etiology of nonalcoholic steatohepatitis (NASH). Monoacylglycerol acyltransferase (MGAT) enzymes convert monoacylglycerol to diacylglycerol, which is the penultimate step in one pathway for triacylglycerol (TAG) synthesis. Hepatic expression of Mogat1, which encodes an MGAT enzyme, is increased in the livers of mice with hepatic steatosis and knocking down Mogat1 improves insulin sensitivity, but whether increased MGAT activity plays a role in the etiology of NASH is unclear. To examine the effects of knocking down Mogat1 in the liver on the development of NASH, C57BL/6 mice were placed on a diet containing high levels of trans fatty acids, fructose, and cholesterol (HTF-C diet) or a low fat control diet for 4 weeks. Mice were then injected with antisense oligonucleotides (ASO) to knockdown Mogat1 or a scrambled ASO control for 12 weeks while remaining on diet. HTF-C diet caused glucose intolerance, hepatic steatosis, and induced hepatic gene expression markers of inflammation, macrophage infiltration, and stellate cell activation. Mogat1 ASO treatment, which suppressed Mogat1 expression in liver, attenuated weight gain, improved glucose tolerance, and decreased hepatic TAG content compared to control ASO-treated mice on HTF-C chow. However, Mogat1 ASO treatment did not reduce hepatic DAG, cholesterol, or free fatty acid content, improve histologic measures of liver injury, or reduce expression of markers of stellate cell activation, liver inflammation, and injury. In conclusion, inhibition of hepatic Mogat1 in HTF-C diet-fed mice improves glucose tolerance and hepatic TAG accumulation without attenuating liver inflammation and injury.
Project description:Nonalcoholic fatty liver disease (NAFLD) is the most common liver disorder with high morbidity and mortality. The current study aims to explore the role of Cullin-associated and neddylation-dissociated protein 1 (CAND1) in the development of NAFLD and the underlying mechanisms. CAND1 is reduced in the liver of NAFLD male patients and high fat diet (HFD)-fed male mice. CAND1 alleviates palmitate (PA) induced lipid accumulation in vitro. Hepatocyte-specific knockout of CAND1 exacerbates HFD-induced liver injury in HFD-fed male mice, while hepatocyte-specific knockin of CAND1 ameliorates these pathological changes. Mechanistically, deficiency of CAND1 enhances the assembly of Cullin1, F-box only protein 42 (FBXO42) and acetyl-CoA acyltransferase 2 (ACAA2) complexes, and thus promotes the ubiquitinated degradation of ACAA2. ACAA2 overexpression abolishes the exacerbated effects of CAND1 deficiency on NAFLD. Additionally, androgen receptor binds to the -187 to -2000 promoter region of CAND1. Collectively, CAND1 mitigates NAFLD by inhibiting Cullin1/FBXO42 mediated ACAA2 degradation
Project description:Cannabinoid 1 receptor (CB1R) expression is upregulated in hepatocytes during viral hepatitis, cirrhosis, and both alcoholic and non-alcoholic fatty liver disease (FLD), whereas its expression is muted under usual physiological conditions. Inhibiting CB1R has been shown to be beneficial in preserving hepatic function in FLD but it is unclear if inhibiting CB1R during an inflammatory response to an acute hepatic injury, such as toxin - induced injury, would also be beneficial. We tested if nullification of hepatocyte-specific CB1R (hCNR1-/-) in mice protects against concanavalin A (Con A) - induced liver injury. We looked for evidence of liver damage and markers of inflammation in response to Con A by measuring liver enzyme levels and proinflammatory cytokines (e.g., TNF-α, IL-1β, IL-6, IL-17) in serum collected from hCNR1-/- and control mice. We observed a shift to the right in the dose-response curve for liver injury and inflammation in hCNR1-/- mice. We also found less inflammatory cell infiltration and focal necrosis in livers of hCNR1-/- mice compared to controls, resulting from downregulated apoptotic markers. This anti-apoptotic mechanism results from increased activation of nuclear factor kappa B (NF-κB), especially membrane-bound TNF-α, via downregulated TNF-α receptor 2 (TNFR2) transcription levels. We also found that CB1R in hepatocytes regulated liver inflammation - related gene transcription. Collectively, these findings provide insight into involvement of CB1R in the pathogenesis of acute liver injury.
Project description:Here, we found that microRNA-223 (miR-223) was highly elevated in hepatocytes after high fat diet (HFD) feeding in mice and in human nonalcoholic steatohepatitis (NASH) samples. Genetic deletion of the miR-223 induced a full spectrum of nonalcoholic fatty liver disease (NAFLD) in mice after long-term (up to one year) HFD feeding including NASH-related steatosis, inflammation, fibrosis and HCC. To better explore the mechanisms underlying the abnormalities observed in HFD-fed miR-223KO mice, we examined hepatic gene expression in 3-month-HFD-fed WT and miR-223KO mice by microarray analysis. Finally, we revealed that miR-223 plays a key role in controlling steatosis-to-NASH progression by inhibiting hepatic Cxcl10 and Taz expression.
Project description:Chronic kidney disease (CKD) is one of the major global health problems with high incidence, poor prognosis and high medical cost. However, few pharmacological options are available for CKD. Metformin is widely used for treatment of type-2 diabetes, but recent works showed that metformin ameliorates tumor progression, inflammatory disease and tissue fibrosis. Whether metformin ameliorates non-diabetic chronic glomerular disease and CKD is unexplored. Here we showed that metformin or losartan (used as control) has protective effects against CKD by suppressing proteinuria, renal inflammation, fibrosis and glomerular injury in Alport syndrome mouse model, which spontaneously manifests chronic glomerular and kidney disease. Transcriptome analysis showed that metformin and losartan influenced molecular pathways of metabolism and inflammation, respectively. While metformin specifically affected genes that were classified as metabolic regulators, losartan specifically altered genes that were classified as inflammatory regulators. Metformin also induced multiple signaling pathways not affected by losartan. Overall, metformin ameliorates non-diabetic chronic glomerular diseases, and could be considered a therapeutic option for CKD. We used microarrays to investigate the global gene expression underlying the protective effects of metformin on Alport syndrome mice model
Project description:Over half of the mature hepatocytes in mice and humans are aneuploid and yet retain full ability to undergo mitosis. This observation has raised the question whether this unusual somatic genetic variation evolved as an adaptive mechanism to hepatic injury. According to this model, hepatotoxic insults would select for hepatocytes with specific numerical chromosome abnormalities, rendering them differentially resistant to the injury. To test this hypothesis, we utilized a strain of mice heterozygous for a mutation in homogentisic acid dioxygenase (Hgd), located on chromosome 16. Loss of this allele can protect from fumarylacetoacetate hydrolase (Fah) deficiency. When adult Hgd+/- Fah-/- mice were exposed to chronic liver damage, injury-resistant nodules consisting of Hgd-null hepatocytes rapidly emerged. To determine whether aneuploidy played a role in this phenomenon, array comparative genomic hybridization (aCGH) and metaphase karyotyping were performed. Strikingly, loss of chromosome 16 was dramatically enriched in all mice that became completely resistant to tyrosinemia-induced hepatic injury. The frequency of chromosome 16-specific aneuploidy was ~50%. This result provides proof-of-principle that the selection of a specific aneuploid karyotype can result in the adaptation of hepatocytes to chronic liver injury. The extent to which aneuploidy promotes hepatic adaptation in humans is under investigation. 8 mouse hepatocyte samples were analyzed. Genomic DNA samples were derived from wild type mice (2), Hgd-/- Fah-/- mice off NTBC (2) and Hgd+/- Fah-/- off NTBC (4). Samples were compared to sex-mismatched reference genomic DNA isolated from wild type mouse splenocytes.
Project description:Insufficient mitochondrial quantity in brown adipose tissue (BAT) causes defective thermogenesis and positive energy balance, which is coupled with the development of obesity. Whether disturbance of mitochondrial quality affects BAT function remains unknown. Here, we describe that the brown adipocyte-specific Leucine-rich PPR motif-containing protein knockout mice (LrpprcBKO) exhibited mitochondrial electron transport chain (ETC) proteome imbalance and a complete loss of the -adrenergic-stimulated thermogenesis at room temperature (RT), due to specific reduction of mtDNA-encoded genes. However, the LrpprcBKO mice were lean at normal chow and were protected against high-fat-diet-induced metabolic abnormalities, such as obesity, insulin resistance, adipose inflammation, hepatic steatosis, and hypertriglyceridemia. The beige adipocytes in inguinal white adipose tissue were expanded in LrpprcBKO mice at RT, but not at thermoneutrality. However, BAT thermogenic defects and metabolic benefits were present in LrpprcBKO mice regardless of ambient temperatures. Collectively, our results reveal that a thermogenesis-incapable BAT with mitochondrial ETC proteome imbalance can improve systemic metabolism, suggesting BAT’s contributions to thermoregulation and systemic metabolism can be uncoupled.
Project description:Background: Hepatic ischemia–reperfusion (I/R) injury is a major complication leading to surgical failures in liver resection, transplantation, and hemorrhagic shock. The role of cytokine macrophage migration inhibitory factor (MIF) in hepatic I/R injury is unclear. Methods: We examined changes of MIF expression in mice after hepatic I/R surgery and hepatocytes challenged with hypoxia–reoxygenation (H/R) insult. Subsequently, MIF global knock-out mice and mice with adeno-associated-virus (AAV)-delivered MIF overexpression were subjected to hepatic I/R injury. Hepatic histology, the inflammatory response, apoptosis and oxidative stress were monitored to assess liver damage. The molecular mechanisms of MIF function were explored in vivo and in vitro. Results: MIF was significantly upregulated in the serum whereas decreased in liver tissues of mice after hepatic I/R injury. MIF knock-out effectively attenuated I/R -induced liver inflammation, apoptosis and oxidative stress in vivo and in vitro, whereas MIF overexpression significantly aggravated liver injury. Via RNA-seq analysis, we found a significant decreased trend of MAPK pathway in MIF knock-out mice subjected hepatic I/R surgery. Using the apoptosis signal-regulating kinase 1 (ASK1) inhibitor NQDI-1 we determined that, mechanistically, the protective effect of MIF deficiency on hepatic I/R injury was dependent on the suppressing of the ASK1-JNK/P38 signaling pathway. Moreover, we found MIF inhibitor ISO-1 alleviate hepatic I/R injury in mice. Conclusion: Our results confirm that MIF deficiency suppresses the ASK1-JNK/P38 pathway and protects the liver from I/R -induced injury. Our findings suggest MIF as a novel biomarker and therapeutic target for the diagnosis and treatment of hepatic I/R injury.. We then performed gene expression profiling analysis using data obtained from RNA-seq of 6 different liver tissues of mice subjected to hepatic I/R injury.
Project description:Hepatic injury provoked by cold storage is a major problem affecting liver transplantation, as exposure to cold induces apoptosis in hepatic tissues. Long noncoding RNAs (lncRNAs) are increasingly understood to regulate apoptosis, but the contribution of lncRNAs to cold-induced liver injury remains unknown. Using RNA-seq, we determined the differential lncRNA expression profile in mouse livers after cold storage and found that expression of the lncRNA TUG1 was significantly down-regulated. Over-expression of TUG1 attenuated cold-induced apoptosis in mouse hepatocytes and liver sinusoidal endothelial cells LSECs, in part by blocking mitochondrial apoptosis and ER stress pathways. Moreover, TUG1 attenuated apoptosis, inflammation and oxidative stress in vivo in livers subjected to cold storage. Over-expression of TUG1 also improved hepatocyte function and prolonged hepatic graft survival rates in mice. These results suggest that the lncRNA TUG1 exerts a protective effect against cold-induced liver damage by inhibiting apoptosis in mice, and suggests a potential role for TUG1 as a target for the prevention of cold-induced liver damage in liver transplantation.