Project description:Analysis of Class II Histone Deacetylase (HDAC) regulation of hepatic gluconeogenesis at the gene expression level. We show that in liver, Class IIa HDACs (HDAC4, 5, and 7) are all phosphorylated and excluded from the nucleus by AMPK family kinases. In response to the fasting hormone glucagon, Class IIa HDACs rapidly translocate to the nucleus where they directly bind to the promoters of gluconeogenic enzymes such as G6Pase. In turn, HDAC4/5 mediate the acute transcriptional induction of these genes via deacetylation and activation of Foxo family transcription factors. Loss of Class IIa HDACs in the murine liver results in inhibition of FOXO target genes and lowers blood glucose, resulting in increased glycogen storage. Total RNA obtained from primary hepatocytes infected with shGFP or shHDAC4 & 5 subjected to 2 or 4 hours treatment with DMSO or forskolin.
Project description:Analysis of Class II Histone Deacetylase (HDAC) regulation of hepatic gluconeogenesis at the gene expression level. We show that in liver, Class IIa HDACs (HDAC4, 5, and 7) are all phosphorylated and excluded from the nucleus by AMPK family kinases. In response to the fasting hormone glucagon, Class IIa HDACs rapidly translocate to the nucleus where they directly bind to the promoters of gluconeogenic enzymes such as G6Pase. In turn, HDAC4/5 mediate the acute transcriptional induction of these genes via deacetylation and activation of Foxo family transcription factors. Loss of Class IIa HDACs in the murine liver results in inhibition of FOXO target genes and lowers blood glucose, resulting in increased glycogen storage.
Project description:Histone deacetylases (HDACs) are important regulators of epigenetic gene modification that are involved in the transcriptional control of metabolism. In particular class IIa HDACs have been shown to affect hepatic gluconeogenesis and previous approaches revealed that their inhibition reduces blood glucose in type 2 diabetic mice. In the present study, we aimed to evaluate the potential of class IIa HDAC inhibition as a therapeutic opportunity for the treatment of metabolic diseases. For that, siRNAs selectively targeting HDAC4, 5 and 7 were selected and used to achieve a combinatorial knockdown of these three class IIa HDAC isoforms. Subsequently, the hepatocellular effects as well as the impact on glucose and lipid metabolism were analyzed in vitro and in vivo. The triple knockdown resulted in a statistically significant decrease of gluconeogenic gene expression in a murine hepatic cell line as well as in human primary hepatocytes. Despite a similar HDAC-induced downregulation of hepatic genes involved in gluconeogenesis in mice using a liver-specific lipid nanoparticle siRNA formulation, the in vivo effects on whole body glucose metabolism were only limited and did not outweigh the safety concerns observed by histopathological analysis in spleen and kidney. Mechanistically, Affymetrix gene chip analysis and gene expression studies provide evidence that class IIa HDACs directly target and thus regulate the expression of HNF4α and FOXP1 in the liver, thereby modifying gene regulatory mechanisms mediating glucose and lipid metabolism and transport. In conclusion, the combinatorial knockdown of HDAC4, 5 and 7 by therapeutic siRNAs affected multiple pathways in vitro and in vivo leading to the downregulation of genes involved in gluconeogenesis. However, the effects on the gene expression level were not paralleled by a significant reduction of gluconeogenesis in mice, as shown in pyruvate tolerance tests. However, the liver-specific inhibition of these HDAC isoforms was associated with severe adverse effects in vivo, making this approach not a viable treatment option for chronic metabolic disorders like type 2 diabetes.
Project description:Sex differences in liver gene expression are dictated by sex-differences in circulating growth hormone (GH) profiles. Presently, the pituitary hormone dependence of mouse liver gene expression was investigated on a global scale to discover sex-specific early GH response genes that might contribute to sex-specific regulation of downstream GH targets and to ascertain whether intrinsic sex-differences characterize hepatic responses to plasma GH stimulation. RNA expression analysis using 41,000-feature microarrays revealed two distinct classes of sex-specific mouse liver genes: genes subject to positive regulation (class-I) and genes subject to negative regulation by pituitary hormones (class-II). Genes activated or repressed in hypophysectomized (Hypox) mouse liver within 30-90min of GH pulse treatment at a physiological dose were identified as direct targets of GH action (early response genes). Intrinsic sex-differences in the GH responsiveness of a subset of these early response genes were observed. Notably, 45 male-specific genes, including five encoding transcriptional regulators that may mediate downstream sex-specific transcriptional responses, were rapidly induced by GH (within 30min) in Hypox male but not Hypox female mouse liver. The early GH response genes were enriched in 29 male-specific targets of the transcription factor Mef2, whose activation in hepatic stellate cells is associated with liver fibrosis leading to hepatocellular carcinoma, a male-predominant disease. Thus, the rapid activation by GH pulses of certain sex-specific genes is modulated by intrinsic sex-specific factors, which may be associated with prior hormone exposure (epigenetic mechanisms) or genetic factors that are pituitary-independent, and could contribute to sex-differences in predisposition to liver cancer or other hepatic pathophysiologies.
Project description:Class IIa histone deacetylases (HDACs) are a family of enzymes that despite their name, do not have any measurable histone deacetylase activity but they function as multi-protein interaction hubs due to the presence of a prolonged N-terminal domain. Here we show that HDAC7, a member of the Class IIa HDAC family, is a chaperone for Histone H3.3 and, interacts with H3.3 and HIRA on chromatin. Specific inhibition of HDAC7 expression with subtype specific siRNAs results in inhibition of the interaction of H3.3 with HIRA, while the association of H3.3 with DAXX and H3K9me3 is significantly increased, resulting in H3.3 being deposited on H3K9me3+/DAPI+ heterochromatin nuclear foci with observed changes in RNA expression. This drives substantial alteration of cancer cell gene expression as well as inhibition of the stemness phenotype for cancer cells. To understand the genome wide effect on expression, we perform RNA-seq following HDAC7 knockdown.
Project description:Introgressed variants from other species can be an important source of genetic variation because they may arise rapidly, can include multiple mutations on a single haplotype, and have often been pretested by selection in the species of origin. Although introgressed alleles are generally deleterious, several studies have reported introgression as the source of adaptive alleles-including the rodenticide-resistant variant of Vkorc1 that introgressed from Mus spretus into European populations of Mus musculus domesticus. Here, we conducted bidirectional genome scans to characterize introgressed regions into one wild population of M. spretus from Spain and three wild populations of M. m. domesticus from France, Germany, and Iran. Despite the fact that these species show considerable intrinsic postzygotic reproductive isolation, introgression was observed in all individuals, including in the M. musculus reference genome (GRCm38). Mus spretus individuals had a greater proportion of introgression compared with M. m. domesticus, and within M. m. domesticus, the proportion of introgression decreased with geographic distance from the area of sympatry. Introgression was observed on all autosomes for both species, but not on the X-chromosome in M. m. domesticus, consistent with known X-linked hybrid sterility and inviability genes that have been mapped to the M. spretus X-chromosome. Tract lengths were generally short with a few outliers of up to 2.7 Mb. Interestingly, the longest introgressed tracts were in olfactory receptor regions, and introgressed tracts were significantly enriched for olfactory receptor genes in both species, suggesting that introgression may be a source of functional novelty even between species with high barriers to gene flow.
Project description:Unlike class I Histone deacetylase (HDAC) members (HDAC1, 2, 3, etc.), HDAC5, a class IIa HDAC member, is downregulated in multiple solid tumors, including pancreatic cancer, and its loss is associated with unfavorable prognosis. Additionally, HDAC5’s expression correlates negatively with arachidonic acid (AA) metabolism, which is highly implicated in inflammatory responses and cancer progression. This study aimed to elucidate the role of HDAC5 in AA metabolism and its prospect in the treatment of pancreatic cancer.
Project description:Translational research is commonly performed in the C57B6/J mouse strain, chosen for its genetic homogeneity and phenotypic uniformity. Here, we evaluate the suitability of the white-footed deer mouse (Peromyscus leucopus) as a model organism for aging research, offering a comparative analysis against C57B6/J and diversity outbred (DO) Mus musculus strains. Our study includes comparisons of body composition, skeletal muscle function, and cardiovascular parameters, shedding light on potential applications and limitations of P. leucopus in aging studies. Notably, P. leucopus exhibits distinct body composition characteristics, emphasizing reduced muscle force exertion and a unique metabolism, particularly in fat mass. Cardiovascular assessments showed changes in arterial stiffness, challenging conventional assumptions and highlighting the need for a nuanced interpretation of aging-related phenotypes. Our study also highlights inherent challenges associated with maintaining and phenotyping P. leucopus cohorts. Behavioral considerations, including anxiety-induced responses during handling and phenotyping assessment, pose obstacles in acquiring meaningful data. Moreover, the unique anatomy of P. leucopus necessitates careful adaptation of protocols designed for Mus musculus. While showcasing potential benefits, further extensive analyses across broader age ranges and larger cohorts are necessary to establish the reliability of P. leucopus as a robust and translatable model for aging studies.
Project description:Class IIa histone deacetylases (HDACs) are signal-responsive regulators of gene expression involved in vascular homeostasis. To investigate the differential role of class IIa HDACs for the regulation of angiogenesis, we used siRNA to specifically suppress the individual HDAC isoenzymes. Among the HDAC isoforms tested, silencing of HDAC5 exhibited a unique pro-angiogenic effect evidenced by increased endothelial cell migration, sprouting and tube formation. Consistently, overexpression of HDAC5 decreased sprout formation, indicating that HDAC5 is a negative regulator of angiogenesis. The anti-angiogenic activity of HDAC5 was independent of MEF2 binding and its deacetylase activity, but required a nuclear localization indicating that HDAC5 might affect the transcriptional regulation of gene expression. To identify putative HDAC5 targets, we performed microarray expression analysis. Silencing of HDAC5 increased the expression of fibroblast growth factor 2 (FGF2) and angiogenic guidance factors including Slit2. Antagonization of FGF2 or Slit2 reduced sprout induction in response to HDAC5 siRNA. ChIP assays demonstrate that HDAC5 binds to the promoter of FGF2 and Slit2. In summary, HDAC5 represses angiogenic genes, like FGF2 and Slit2, which causally contribute to capillary-like sprouting of endothelial cells. The de-repression of angiogenic genes by HDAC5 inactivation may provide a useful therapeutic target for induction of angiogenesis. Experiment Overall Design: 6 samples: 3x siSCRAMBLED transfected HUVEC (control) + 3x siHDAC5 transfected HUVEC 24h after transfection