The mitochondrial calcium uniporter has been proposed to coordinate the organelle's energetics with cytosolic calcium signaling. Previous studies have shown that the uniporter current is extremely high in mitochondria from brown adipose tissue (BAT), yet the contribution of the uniporter to BAT physiology in vivo is not known. Here, we report the generation and characterization of a mouse model lacking Mcu, the pore forming subunit of the uniporter, specifically in BAT (BAT-Mcu-KO). BAT-Mcu-KO mice are born in Mendelian ratios on a C57BL6/J genetic background, without any overt phenotypes. Although uniporter based calcium uptake is selectively ablated in BAT mitochondria, these mice are able to defend their body temperature in response to cold challenge and exhibit a normal body weight trajectory on a high fat diet. BAT transcriptional profiles at baseline and following cold-challenge are intact and not impacted by loss of Mcu. Unexpectedly, we found that cold powerfully activates the ATF4-dependent integrated stress response in BAT, and increases both circulating FGF21 and GDF15 levels, raising the hypothesis that the integrated stress response partly underlies the pleiotropic effects of BAT on systemic metabolism. Our study demonstrates that the uniporter is largely dispensable for BAT thermogenesis, and unexpectedly, uncovers a striking activation of the integrated stress response of BAT to cold challenge. Overall design: RNA-seq was performed on BAT RNA isolated from BAT-Mcu-KO and control animals housed for 6 hours at 4C or room temp (RT). Samples include 6 control animals at RT; 5 control animals at 4C; 6 BAT-Mcu-KO animals at RT; and 6 BAT-Mcu-KO animals at 4C.
Exploring the In Vivo Role of the Mitochondrial Calcium Uniporter in Brown Fat Bioenergetics.
Sex, Specimen part, Cell line, Subject
View SamplesRapid advances in genotyping and sequencing technology have dramatically accelerated the discovery of genes underlying human disease. Elucidating the function of such genes and understanding their role in pathogenesis, however, remains challenging. Here, we introduce a genomic strategy to functionally characterize such genes, and apply it to LRPPRC (leucine-rich PPR-motif containing), a poorly studied gene that is mutated in Leigh Syndrome, French Canadian type (LSFC).
Mitochondrial and nuclear genomic responses to loss of LRPPRC expression.
Specimen part, Cell line
View SamplesMitochondrial oxidative function is tightly controlled to maintain energy homeostasis in response to nutrient and hormonal signals. An important cellular component in the energy sensing response is the target of rapamycin (TOR) kinase pathway; however whether and how mTOR controls mitochondrial oxidative activity is unknown. Here, we show that mTOR kinase activity stimulates mitochondrial gene expression and oxidative function. In skeletal muscle cells and TSC2-/- MEFs, the mTOR inhibitor rapamycin largely decreased gene expression of mitochondrial transcriptional regulators such as PGC-1alpha and the transcription factors ERRalpha and NRFs. As a consequence, mitochondrial gene expression and oxygen consumption were reduced upon mTOR inhibition. Using computational genomics, we identified the transcription factor YY1 as a common target of mTOR and PGC-1alpha that controls mitochondrial gene expression. Inhibition of mTOR resulted in a failure of YY1 to interact and be coactivated by PGC-1alpha. Notably, knock-down of YY1 in skeletal muscle cells caused a significant decrease in mRNAs of mitochondrial regulators and mitochondrial genes that resulted in a decrease in respiration. Moreover, YY1 was required for rapamycin-dependent repression of mitochondrial genes. Thus, we have identified a novel mechanism in which a nutrient sensor (mTOR) balances energy metabolism via transcriptional control of mitochondrial oxidative function. These results have important implications for our understanding of how these pathways might be altered in metabolic diseases and cancer.
mTOR controls mitochondrial oxidative function through a YY1-PGC-1alpha transcriptional complex.
No sample metadata fields
View SamplesMitochondria are centers of metabolism and signaling whose content and function must adapt to changing cellular environments. The biological signals that initiate mitochondrial restructuring and the cellular processes that drive this adaptive response are largely obscure. To better define these systems, we performed matched quantitative genomic and proteomic analyses of mouse muscle cells as they performed mitochondrial biogenesis. We find that proteins involved in cellular iron homeostasis are highly coordinated with this process, and that depletion of cellular iron results in a rapid, dose-dependent decrease of select mitochondrial protein levels and oxidative capacity. We further show that this process is universal across a broad range of cell types and fully reversed when iron is reintroduced. Collectively, our work reveals that cellular iron is a key regulator of mitochondrial biogenesis, and provides quantitative datasets that can be leveraged to explore post-transcriptional and post-translational processes that are essential for mitochondrial adaptation.
Complementary RNA and protein profiling identifies iron as a key regulator of mitochondrial biogenesis.
Cell line, Treatment
View SamplesMicroarray time-course of mouse myotubes transduced with the transcriptional co-activator PGC-1alpha, which is known to induce mitochondrial biogenesis in muscle cells.
Systematic identification of human mitochondrial disease genes through integrative genomics.
Cell line
View SamplesWe report gene expression in human neutrophils isolated by two methods: Polymorphprep (~95% purity) and negative selection (~99% purity) from two healthy donors - one donor with low eosinophil contamination of neutrophils and one donor with high eosinophil contamination of neutrophils. We report the effect of the presence of contaminating leukocytes in neutrophil preparations, and in reponse to inflammatory cytokines TNF-alpha and GM-CSF. Overall design: Healthy human neutrophils were isolated using Polymorphprep or negative selection, and incubated for 1h in the absence or presence of TNF-alpha or GM-CSF. RNA was analysed by Illumina HiSeq 2000. The results from n=2 donors were analysed as biological replicates for differential expression analysis.
Whose Gene Is It Anyway? The Effect of Preparation Purity on Neutrophil Transcriptome Studies.
No sample metadata fields
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 SamplesComparing gene expression profile in 3T3-F442A adipocytes with shRNA against TRPV4 or GFP. TRPV4 is an ion channel expressed in adipocytes. Results provided information that how loss-of-function of TRPV4 affects gene expression in adipocytes.
TRPV4 is a regulator of adipose oxidative metabolism, inflammation, and energy homeostasis.
No sample metadata fields
View SamplesSmall RNAs (sRNAs) are hypothesized to contribute to hybrid vigor because they maintain genome integrity, contribute to genetic diversity, and control gene expression. We used Illumina sequencing to assess how sRNA populations vary between two maize inbred lines (B73, Mo17) and their hybrid. We sampled sRNAs from the seedling shoot apex and the developing ear, two rapidly growing tissues that program the greater growth of maize hybrids. We found that parental differences in siRNAs primarily originate from repeat regions. Although the maize genome contains greater number and complexity of repeats compared to Arabidopsis or rice, we confirmed that like these simpler plant genomes, 24-nt siRNAs whose abundance differs between maize parents also show a trend of downregulation following hybridization. Surprisingly, hybrid vigor is fully maintained when 24-nt siRNAs are globally reduced by mutation of the RNA-dependent RNA polymerase2 (RDR2) encoded by modifier of paramutation1 (mop1). We also discovered that 21-22nt siRNAs derived from a number of distinct retrotransposon families differentially accumulate between B73 and Mo17 as well as their hybrid. Thus, maize possesses a novel source of genetic variation for regulating both transposons and genes at a genomic scale, which may contribute to its high degree of observed heterosis. Overall design: sRNA libraries were derived from RNA isolated from the seedling shoot apex and developing ear tissues from B73, Mo17, B73xMo17 and Mo17xB73. The shoot apex was chosen because it is enriched for meristematic tissue where cell proliferation occurs, rates of organ initiation are determined, and organ size is specified. The developing ear was examined because it is enriched in meristematic tissue and is undergoing rapid growth, and also because the mature ear shows the highest degree of heterosis. Total RNA was isolated and separated on a 15% TBE-Urea polyacrylamide gel. Using a 10-bp ladder, the sRNA fraction representing 10-40-bp was excised. sRNA libraries were prepared according to Lu et al. (2007) or manufacturer''s instructitions (Illumina). A combination of Perl scripts and FASTX toolkit scripts were used to remove adapters, collapse identical sequences and count reads per sequence. Supplementary processed data text files contain the distinct sRNA sequences for all of the genotypes analyzed in that experiment. Abundance (reads per million) was calculated for each distinct sequence by dividing the number of reads of distinct sRNA in a library by the total number of sRNA reads for that library and multiplying this by 1 million. Genome builds: B73 genome, maizesequence.org release 4a.53 (October, 2009); Mo17 whole genome shotgun clones.
Repeat associated small RNAs vary among parents and following hybridization in maize.
Specimen part, Subject
View SamplesAtherosclerosis is a transmural chronic inflammatory condition of small and large arteries that is associated with adaptive immune responses at all disease stages. However, impacts of adaptive immune reactions on clinically apparent atherosclerosis such as intima lesion (plaque) rupture, thrombosis, myocardial infarction, and aneurysm largely remain to be identified. It is increasingly recognized that leukocyte infiltrates in plaque, media, and adventitia are distinct but their specific roles have not been defined. To map these infiltrates, we employed laser capture microdissection (LCM) to isolate the three arterial wall laminae using apoE-/- mouse aorta as a model. RNA from LCM-separated tissues was extracted and large scale whole genome expression microarrays were prepared. We observed that the quality of the resulting gene expression maps was compromised by tissue RNA carried over from adjacent laminae during LCM. To account for these flaws, we established quality controls and algorithms to improve the predictive power of LCM-derived microarray data. Our approach creates robust transcriptome atlases of normal and atherosclerotic aorta. Assessing LCM transcriptomes for immunity-related mRNAs indicated markedly distinctive gene expression patterns in the three laminae of the atherosclerotic aorta. These mouse mRNA expression data banks can now be mined to address a wide range of questions in cardiovascular biology.
The lamina adventitia is the major site of immune cell accumulation in standard chow-fed apolipoprotein E-deficient mice.
Sex, Age, Specimen part
View Samples