Project description:Background: Several genetic defects of the nucleotide excision repair (NER) pathway, including deficiency of the Excision Repair Cross-Complementing rodent repair deficiency, complementation group 1 (ERCC1), result in pre-mature aging, impaired growth, microcephaly and delayed development of the cerebellum. Such a phenotype also occurs in ERCC1-knockout mice which survive for up to 4 weeks after birth. Therefore, we analyzed cerebellar and hippocamapal transcriptomes of these animals at 3 weeks of age to identify the candidate mechanisms underlying brain consequences of reduced ERCC1 activity. Results: In the cerebellum, the most prominent change was upregulation of genes that are associated with gliosis. Although Purkinje cell degeneration has been reported in some mouse strains with NER impairment, Purkinje cell transcriptome was mostly unaffected by the ERCC1 knockout. In the hippocampus, the gliosis response was minimal. Instead, there was an extensive downregulation of genes related to lipid metabolism including several enzymes of the cholesterol biosynthesis pathway as well as lipoproteins and plasma membrane proteins. Reduced expression of the cholesterol biosynthesis pathway genes was also present in the neocortex of adult mice whose ERCC1 gene was replaced by a mutant allele with a partial activity. Conclusions: Downregulation of forebrain cholesterol biosynthesis genes is a newly identified consequence of ERCC1 deficiency. Its presence in adult mice suggests that it is not a secondary consequence of brain growth impairment. Instead, reduced cholesterol biosynthesis may contribute to such an impairment as well as affect function of mature synapses. We analyzed the hippocampus and cerebellum from three Ercc1-/- and three WT littermates using the Affymetrix Mouse Genome 430_2.0. Data was analyzed using the dChip DNA-Chip analyzer software .
Project description:Background: Several genetic defects of the nucleotide excision repair (NER) pathway, including deficiency of the Excision Repair Cross-Complementing rodent repair deficiency, complementation group 1 (ERCC1), result in pre-mature aging, impaired growth, microcephaly and delayed development of the cerebellum. Such a phenotype also occurs in ERCC1-knockout mice which survive for up to 4 weeks after birth. Therefore, we analyzed cerebellar and hippocamapal transcriptomes of these animals at 3 weeks of age to identify the candidate mechanisms underlying brain consequences of reduced ERCC1 activity. Results: In the cerebellum, the most prominent change was upregulation of genes that are associated with gliosis. Although Purkinje cell degeneration has been reported in some mouse strains with NER impairment, Purkinje cell transcriptome was mostly unaffected by the ERCC1 knockout. In the hippocampus, the gliosis response was minimal. Instead, there was an extensive downregulation of genes related to lipid metabolism including several enzymes of the cholesterol biosynthesis pathway as well as lipoproteins and plasma membrane proteins. Reduced expression of the cholesterol biosynthesis pathway genes was also present in the neocortex of adult mice whose ERCC1 gene was replaced by a mutant allele with a partial activity. Conclusions: Downregulation of forebrain cholesterol biosynthesis genes is a newly identified consequence of ERCC1 deficiency. Its presence in adult mice suggests that it is not a secondary consequence of brain growth impairment. Instead, reduced cholesterol biosynthesis may contribute to such an impairment as well as affect function of mature synapses.
Project description:To map gene regulation downstream of cholesterol overload and NF-kappaB signaling in smooth muscle cells (SMCs), we cultured primary aortic SMCs from wildtype mice with cyclodextrin-complexed cholesterol or the prototypical NF-kappaB activator, tumor necrosis factor (TNF), or both.
Project description:We created mice, which are deficient for Myc specifically in cardiac myocytes by crossing crossed Myc-floxed mice (Mycfl/fl) and MLC-2VCre/+ mice. Serial analysis of earlier stages of gestation revealed that Myc-deficient mice died prematurely at E13.5-14.5. Morphological analyses of E13.5 Myc-null embryos showed normal ventricular size and structure; however, decreased cardiac myocyte proliferation and increased apoptosis was observed. BrdU incorporation rates were also decreased significantly in Myc-null myocardium. Myc-null mice displayed a 3.67-fold increase in apoptotic cardiomyocytes by TUNEL assay. We examined global gene expression using oligonucleotide microarrays. Numerous genes involved in mitochondrial death pathways were dysregulated including Bnip3L and Birc2. Keywords: wildtype vs Myc-null
Project description:This model is from the article:
A model of flux regulation in the cholesterol biosynthesis pathway: Immune mediated graduated flux reduction versus statin-like led stepped flux reduction.
Watterson S, Guerriero ML, Blanc M, Mazein A, Loewe L, Robertson KA, Gibbs H, Shui G, Wenk MR, Hillston J, Ghazal P. Biochimie.
2012 Jun 1. 22664637
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Abstract:
The cholesterol biosynthesis pathway has recently been shown to play an important role in the innate immune response to viral infection with host protection occurring through a coordinate down regulation of the enzymes catalysing each metabolic step. In contrast, statin based drugs, which form the principle pharmaceutical agents for decreasing the activity of this pathway, target a single enzyme. Here, we build an ordinary differential equation model of the cholesterol biosynthesis pathway in order to investigate how the two regulatory strategies impact upon the behaviour of the pathway. We employ a modest set of assumptions: that the pathway operates away from saturation, that each metabolite is involved in multiple cellular interactions and that mRNA levels reflect enzyme concentrations. Using data taken from primary bone marrow derived macrophage cells infected with murine cytomegalovirus or treated with IFNγ, we show that, under these assumptions, coordinate down-regulation of enzyme activity imparts a graduated reduction in flux along the pathway. In contrast, modelling a statin-like treatment that achieves the same degree of down-regulation in cholesterol production, we show that this delivers a step change in flux along the pathway. The graduated reduction mediated by physiological coordinate regulation of multiple enzymes supports a mechanism that allows a greater level of specificity, altering cholesterol levels with less impact upon interactions branching from the pathway, than pharmacological step reductions. We argue that coordinate regulation is likely to show a long-term evolutionary advantage over single enzyme regulation. Finally, the results from our models have implications for future pharmaceutical therapies intended to target cholesterol production with greater specificity and fewer off target effects, suggesting that this can be achieved by mimicking the coordinated down-regulation observed in immunological responses.
Project description:We collected whole genome testis expression data from hybrid zone mice. We integrated GWAS mapping of testis expression traits and low testis weight to gain insight into the genetic basis of hybrid male sterility.