Calorie restriction (CR) is a dietary intervention that extends lifespan and healthspan in a variety of organisms. CR improves mitochondrial energy production, fuel oxidation and reactive oxygen species scavenging in skeletal muscle and other tissues, and these processes are thought to be critical to the benefits of CR. PGC-1a is a transcriptional coactivator that regulates mitochondrial function and is induced by CR. Consequently, many of the mitochondrial and metabolic benefits of CR are attributed to increased PGC-1a activity. To test this model for the first time, we examined the metabolic and mitochondrial response to CR in mice lacking skeletal muscle PGC-1a (MKO). Surprisingly, MKO mice demonstrated a normal improvement in glucose homeostasis in response to CR, indicating that skeletal muscle PGC-1a is dispensable for the whole-body benefits of CR. In contrast, gene expression profiling and electron microscopy demonstrated that PGC-1a is required for the full CR-induced increases in mitochondrial gene expression and mitochondrial density in skeletal muscle. These results demonstrate that PGC-1a is a major regulator of the mitochondrial response to CR in skeletal muscle, but surprisingly show that neither PGC-1a nor mitochondrial biogenesis in skeletal muscle are required for the metabolic benefits of CR.
Skeletal muscle transcriptional coactivator PGC-1α mediates mitochondrial, but not metabolic, changes during calorie restriction.
Specimen part
View SamplesTumor cells exhibit aberrant metabolism characterized by high glycolysis even in the presence of oxygen. This metabolic reprogramming, known as the Warburg effect, provides tumor cells with the substrates and redox potential required for the generation of biomass. Here, we show that the mitochondrial NAD-dependent deacetylase SIRT3 is a crucial regulator of the Warburg effect. SIRT3 loss promotes a metabolic profile consistent with high glycolysis required for anabolic processes in vivo and in vitro. Mechanistically, SIRT3 mediates metabolic reprogramming independently of mitochondrial oxidative metabolism and through HIF1a, a transcription factor that controls expression of key glycolytic enzymes. SIRT3 loss increases reactive oxygen species production, resulting in enhanced HIF1a stabilization. Strikingly, SIRT3 is deleted in 40% of human breast cancers, and its loss correlates with the upregulation of HIF1a target genes. Finally, we find that SIRT3 overexpression directly represses the Warburg effect in breast cancer cells. In sum, we identify SIRT3 as a regulator of HIF1a and a suppressor of the Warburg effect.
SIRT3 opposes reprogramming of cancer cell metabolism through HIF1α destabilization.
Specimen part
View SamplesIn cytotoxic T cells (CTL), Protein Kinase B /Akt is activated by the T cell antigen receptor (TCR) and the cytokine Interleukin 2 (IL2), in part by phosophorylation of Akt by Phospholipid dependent kinase 1 (PDK1).
Protein kinase B controls transcriptional programs that direct cytotoxic T cell fate but is dispensable for T cell metabolism.
Specimen part
View SamplesThe objective of this study was to identify alterations in gene expression during reverse myocardial remodeling in a mouse model of reversible pressure overload.
Collagen isoform shift during the early phase of reverse left ventricular remodelling after relief of pressure overload.
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View SamplesThe ACBP knockout were created by targeted disruption of the gene in mice. The expression profiling was performed on liver tissue from ACBP-/- (KO) and +/+ (WT) mice at the age of 21 days, which in our study is the time immediately before weaning. The mice used for this experiment were taken directly away from their mother. Thus, having free access to chow and breast milk until sacrificed at 8-11am
Disruption of the acyl-CoA-binding protein gene delays hepatic adaptation to metabolic changes at weaning.
Specimen part
View SamplesSeveral ocular diseases involve the iris, notably including oculocutaneous albinism, pigment dispersion syndrome, and exfoliation syndrome. To screen for candidate genes that may be active in these diseases, genome-wide iris gene expression patterns were comparatively analyzed from mouse models of these conditions.
Microarray analysis of iris gene expression in mice with mutations influencing pigmentation.
Age, Specimen part
View SamplesFumarylacetoacetate hydrolase (Fah), the last enzyme of the tyrosine degradation pathway, is specifically expressed in hepatocytes in the liver. Loss of Fah leads to liver failure in mice within 6-8 weeks. This can be prevented by blocking tyrosine degradation upstream of Fah with 2-(2-nitro-4-trifluoromethylbenzoyl)-1,3-cyclohexanedione (NTBC). Here, we investigate the impact of p21 on global gene expression in Fah deficiency.
Loss of p21 permits carcinogenesis from chronically damaged liver and kidney epithelial cells despite unchecked apoptosis.
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View SamplesRecognition and response to gram-positive bacteria by macrophages and dendritic cells is mediated in part through TLR2. We found that that Streptococcus pneumoniae cell wall fragments, containing primarily peptidoglycan and teichoic acids, induced prodigious secretion of IL-10 from macrophages and dendritic cells and was dependent on TLR2 and NOD2, a cytoplasmic CARD-NACHT-LRR protein encoded by Card15. IL-10 secretion in response to cell walls was also dependent on RICK/RIP2, a kinase associated with NOD2, and MYD88 but independent of the ERK/p38 pathway. The reduction of IL-10 secretion by cell wall-activated NOD2-deficient myeloidderived cells translated into downstream effects on IL-10 target gene expression and elevations in subsets of pro-inflammatory cytokine expression normally restrained by autocrine/paracrine effects of IL-10. Since NOD2 is linked to aberrant immune responses in Crohns Disease patients bearing mutations in CARD15, the temporal and quantitative effects of the TLR2/NOD/RICK pathway on IL-10 secretion may affect homeostatic control of immune responses to gram-positive bacteria.
The TLR2-MyD88-NOD2-RIPK2 signalling axis regulates a balanced pro-inflammatory and IL-10-mediated anti-inflammatory cytokine response to Gram-positive cell walls.
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View SamplesTemporal changes of gene expression from 1-wk- to 4-wk and 8-wk-old mouse in heart, kidney and lung. Mammalian somatic growth is rapid in early postnatal life but then slows and eventually ceases in multiple tissues. We hypothesized that there exists a postnatal gene expression program that is common to multiple tissues and is responsible for this coordinate growth deceleration. Consistent with this hypothesis, microarray analysis identified >1600 genes that were regulated with age coordinately in kidney, lung, and heart of juvenile mice, including many genes that regulate proliferation. As examples, we focused on three growth-promoting genes, Igf2, Mest, and Peg3, that were markedly downregulated with age. We conclude that there exists an extensive genetic program occurring during postnatal life. Many of the involved genes are regulated coordinately in multiple organs, including many genes that regulate cell proliferation. At least some of these are themselves apparently regulated by growth, suggesting that, in the embryo, a gene expression pattern is established that allows for rapid somatic growth of multiple tissues but then, during postnatal life, this growth leads to negative-feedback changes in gene expression that in turn slow and eventually halt somatic growth, thus imposing a fundamental limit on adult body size.
An extensive genetic program occurring during postnatal growth in multiple tissues.
Sex, Age, Specimen part
View SamplesSusceptible and Resistant mouse strain, e.g. DBA/2J and C57BL/6J respectively, were inoculated with a highly pathogenic H5N1 influenza A virus (A/Hong Kong/213/2003) for 72 hours.
Host genetic variation affects resistance to infection with a highly pathogenic H5N1 influenza A virus in mice.
Sex
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