Project description:Purpose: to identify the impact of cdk4 inhibition on genes and pathways involved in age-associated liver disorders using next generation sequencing on young and control- or PD0332991-treated aged mice. Methods: RNA was isolated from livers of young (2 month old) and old (20-22 month old) C57Bl6 mice. Old mice were either either control-aged mice or PD-0332991 treated aged mice (450mg/dk for 2 weeks). The three conditions were represented in triplicate. Raw reads passing quality filtration were aligned to the mm10 mouse genome using UCSC annotations by pseudoalignment in Kallisto. All reasonably expressed transcripts were submitted for statistical analysis to identify age-altered transcripts corrected by cdk4 inhibition. Results: We mapped a minimum of 20 million reads per sample, which corresponded to a total of 25,240 transcripts. Of these, 12,551 were considered reasonably expressed and were included in analysis comparing control-aged v young and PD0332991-treated-aged v young. Conclusion: Inhibition of cdk4 in ages wildtype mice by cdk4 inhibitor PD-0332991 reduces CEBPa-p300 and reduced aged-related alterations of hepatic structure and function.
Project description:Pyrimidine catabolism is implicated in hepatic steatosis. Dihydropyrimidine Dehydrogenase (DPYD) is an enzyme responsible for uracil and thymine catabolism, and DPYD human genetic variability affects clinically observed toxicity following 5-Fluorouracil (5-FU) administration. In an in vitro model of diet-inducedfatty acid-induced steatosis, the pharmacologic inhibition of DPYD resulted in protection from lipid accumulation. Additionally, a gain-of-function mutation of DPYD, created through clustered regularly interspaced short palindromic repeats associated protein 9 (CRISPR-Cas9) engineering, led to an increased lipid burden, which was associated with altered mitochondrial functionality in a hepatocarcionma cell line. The studies presented herein describe a novel role for DPYD in hepatocyte metabolic regulation as a modulator of hepatic steatosis.
Project description:Hepatic steatosis is a very common response to liver injury and often attributed to metabolic disorders. Prior studies have demonstrated the efficacy of a biotechnologically produced oyster mushroom (Pleurotus sajor-caju, PSC) in alleviating hepatic steatosis in obese Zucker rats. This study aims to elucidate molecular events underlying the anti-steatotic effects of PSC.
Project description:Ceramides contribute to the lipotoxicity that underlies diabetes, hepatic steatosis, and heart disease. By genetically engineering mice, we deleted the enzyme dihydroceramide desaturase-1 (DES1) which inserts a conserved double bond into the backbone of ceramides and other predominant sphingolipids. Ablation of DES1 from whole animals, or tissue-specific deletion in the liver, and/or adipose tissue resolved hepatic steatosis and insulin resistance in mice caused by leptin deficiency or obesogenic diets. Mechanistic studies revealed new ceramide actions that promoted lipid uptake and storage and impaired glucose utilization, none of which could be recapitulated by (dihydro)ceramides that lacked the critical double bond. These studies suggest that inhibition of DES1 may provide a means of treating hepatic steatosis and cardiometabolic disorders.
Project description:We demonstrated that RORa-deficient staggerer mice (RORasg/sg) fed with a high fat diet (HFD) showed reduced adiposity and hepatic triglyceride levels compared to wild type (WT) littermates and were resistant to the development of hepatic steatosis, adipose-associated inflammation, and insulin resistance. Gene expression profiling showed that many genes involved in triglyceride synthesis and storage, including Cidec, Cidea, and Mogat1, were expressed at much lower levels in liver of RORasg/sg mice. In addition to reduced lipid accumulation, inflammation was greatly diminished in white adipose tissue (WAT) of RORasg/sg mice fed with a HFD. The infiltration of macrophages and the expression of many immune-response and pro-inflammatory genes, including those encoding various chemo/cytokines, toll-like receptors, and TNF signaling proteins, were significantly reduced in RORasg/sg WAT. Moreover, RORasg/sg mice fed with a HFD were protected from the development of insulin resistance. Together, these results indicate that RORa plays a critical role in the regulation of several aspects of metabolic syndrome. Therefore, RORa may provide a novel therapeutic target in the management of obesity and associated metabolic diseases. Liver and white adipose tissue (WAT) total RNAs were purified from 5 WT and 5 RORasg/sg (natural deletion of RORa gene in mice) mice fed with a high fat diet for 6 weeks. Then samples were applied on Agilent mouse genome chip.
Project description:The impairment of the intestinal barrier will lead to the accumulation of fat and harmful substances in the liver, inducing hepatic steatosis or steatohepatitis. Zhang et al. identified NSD2 in the intestine as a novel and essential regulator of hepatic steatosis. NSD2 directly regulates transcriptional activation of ERN1 through the modification of H3 dimethylated on lysine 36 (H3K4me36), thereby activating the ERN1-JNK axis to induce inflammatory response, intestinal barrier impairment, and hepatic steatosis. This functional mechanism of NSD2 provides a potential therapeutic target for this disease.
Project description:The impairment of the intestinal barrier will lead to the accumulation of fat and harmful substances in the liver, inducing hepatic steatosis or steatohepatitis. Zhang et al. identified NSD2 in the intestine as a novel and essential regulator of hepatic steatosis. NSD2 directly regulates transcriptional activation of ERN1 through the modification of H3 dimethylated on lysine 36 (H3K4me36), thereby activating the ERN1-JNK axis to induce inflammatory response, intestinal barrier impairment, and hepatic steatosis. This functional mechanism of NSD2 provides a potential therapeutic target for this disease.
Project description:Individuals with hepatic steatosis often display several metabolic abnormalities including insulin resistance and muscle atrophy. Previously, we found that hepatic steatosis results in an altered hepatokine secretion profile, thereby inducing skeletal muscle insulin resistance via inter-organ crosstalk. In this study, we aimed to investigate whether the altered secretion profile in the state of hepatic steatosis also induces skeletal muscle atrophy via effects on muscle protein turnover. To investigate this, eight-week-old male C57BL/6J mice were fed a chow (4.5% fat) or a high-fat diet (HFD; 45% fat) for 12 weeks to induce hepatic steatosis, after which the livers were excised and cut into ~200 µm slices. Slices were cultured to collect secretion products (conditioned medium; CM). Differentiated L6-GLUT4myc myotubes were incubated with chow or HFD CM to measure glucose uptake. Differentiated C2C12 myotubes were incubated with chow or HFD CM to measure protein synthesis and breakdown, and gene expression via RNA sequencing. Furthermore, proteomics analysis was performed in chow and HFD CM. It was found that HFD CM caused insulin resistance in L6-GLUT4myc myotubes compared with chow CM, as indicated by a blunted insulin-stimulated increase in glucose uptake. Furthermore, protein breakdown was increased in C2C12 cells incubated with HFD CM, while there was no effect on protein synthesis. RNA profiling of C2C12 cells indicated that 197 genes were differentially expressed after incubation with HFD CM, compared with chow CM, and pathway analysis showed that pathways related to anatomical structure and function were enriched. Proteomic analysis of the CM showed that 32 proteins were differentially expressed in HFD CM compared with chow CM. Pathway enrichment analysis indicated that these proteins had important functions with respect to insulin-like Growth Factor transport and uptake, and affect post-translational processes, including protein folding, protein secretion and protein phosphorylation. In conclusion, the results of this study support the hypothesis that secretion products from the liver contribute to the development of muscle atrophy in individuals with hepatic steatosis.