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 SamplesMyelopoiesis is impaired in Raptor-deleted mice (CreER-Rptor-flox/flox). To evaluate the transcriptional changes in myeloid precursors , we isolated CMP (LinSca-1c-Kit+CD34+FcRII/IIImid), GMP (LinSca-1c-Kit+CD34+FcRII/IIIhigh) and Lin (B220, Ly6C, Ly6G, CD3, Ter-119) negative cells (Lin) from bone marrow of WT or CreER-Rptor-flox/flox mice. RNA was isolated from CMP and GMP immediately after sorting and Lin- cells were cultured for 12 hours with M-CSF (10 ng/mL) in 10% FBS and 1% P/S DMEM before RNA isolation.
Critical roles of mTORC1 signaling and metabolic reprogramming for M-CSF-mediated myelopoiesis.
Sex
View SamplesPGC1a is a transcriptional coactivator that regulates energy metabolism. PGC1a is highly expressed in a subset of melanoma tumors and cell lines. We generated gene-expression profile of control and PGC1alpha depleted A375P melanoma cells, a melanoma cell line that expresses very high levels of PGC1a to investigate the role of this gene in melanoma.
PGC1α expression defines a subset of human melanoma tumors with increased mitochondrial capacity and resistance to oxidative stress.
Specimen part
View SamplesTranscriptional profiling of murine dendritic cells stimulated with LPS and IFNg after shRNA knockdown of redox regulators. Overall design: shRNA targeting redox regulators were delivered to bone marrow derived dendritic cells. Cells were stimulated with LPS and IFNg prior to transcriptional profiling by RNAseq over a time course. Each sample sequenced on two Illumina lanes.
Nitric Oxide Engages an Anti-inflammatory Feedback Loop Mediated by Peroxiredoxin 5 in Phagocytes.
Specimen part, Treatment, Subject
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 SamplesAlternative splicing of the Pkm gene product generates the PKM1 and PKM2 isoforms of pyruvate kinase, and PKM2 expression is closely linked to embryogenesis, tissue regeneration, and cancer. To interrogate the functional requirement for PKM2 during development and tissue homeostasis, we generated germline PKM2 null mice (Pkm2-/-). Unexpectedly, despite being the primary isoform expressed in most wild-type adult tissues, we found that Pkm2-/- mice are viable and fertile. Thus, PKM2 is not required for embryonic or postnatal development. Loss of PKM2 leads to compensatory expression of PKM1 in the tissues that normally express PKM2. Strikingly, PKM2 loss leads to spontaneous development of hepatocellular carcinoma (HCC) with high penetrance that is accompanied by progressive changes in systemic metabolism characterized by altered systemic glucose homeostasis, inflammation, and hepatic steatosis. Therefore, in addition to its role in cancer metabolism, PKM2 plays a role in controlling systemic metabolic homeostasis and inflammation, thereby preventing HCC by a non-cell-autonomous mechanism. Overall design: RNA was isolated from flash frozen ground whole liver tissue of 35 week old PKM2 KO and WT mice. Three independent mice from each condition were used as biological replicates.
Germline loss of PKM2 promotes metabolic distress and hepatocellular carcinoma.
Specimen part, Subject
View SamplesMitochondrial defects are associated with a spectrum of human disorders, ranging from rare, inborn errors of metabolism to common, age-associated diseases such as diabetes and neurodegeneration. In lower organisms, genetic retrograde signaling programs have been identified that promote cellular and organism survival in the face of mitochondrial dysfunction. Here, we characterized the transcriptional component of the human mitochondrial retrograde response in an inducible model of mitochondrial dysfunction.
Mitochondrial dysfunction remodels one-carbon metabolism in human cells.
Cell line
View SamplesWe investigated the role of mTORC1 in murine hematopoiesis by conditionally deleting the Raptor gene in murine hematopoietic stem cells. We observed mutliple alterations evoked by Raptor loss in hematopoiesis and profiled gene-expression alterations induced by raptor loss in Flt3-Lin-Sca1+cKit+ hematopoietic stem and progenitor enriched cell populations, 5 weeks post Raptor deletion.
mTOR complex 1 plays critical roles in hematopoiesis and Pten-loss-evoked leukemogenesis.
Specimen part
View SamplesControl and Liver Insulin Receptor KO mice (LIRKO) were sacrificed in the non-fasted state. RNA was prepared from liver samples and subjected to expression microarray analysis
Flavin-containing monooxygenase 3 as a potential player in diabetes-associated atherosclerosis.
Specimen part
View SamplesSirtuin 3 (SIRT3) is an NAD+-dependent deacetylase downregulated in aging and age-associated diseases such as cancer and neurodegeneration, and high fat diet (HFD)-induced metabolic disorders. Thus, we performed a small molecule screen and identified an unexpected metabolic vulnerability associated with SIRT3 loss. Overall design: RNA sequencing in SV40T immortalized SIRT3 WT (triplicates) and SIRT3 KO MEF (duplicates) lines under normal conditions.
Small-Molecule Screen Identifies De Novo Nucleotide Synthesis as a Vulnerability of Cells Lacking SIRT3.
Specimen part, Cell line, Subject
View Samples