We studied genome-wide expression profiles of C. elegans young adult worms, complex I mutant gas-1(fc21) compare to the wild type N2 Bristol worm and the effect of different antioxidant drug treatment on the gene expression profile in gas-1(fc21).
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Specimen part
View SamplesPrimary mitochondrial respiratory chain (RC) diseases are heterogeneous in etiology and manifestations but collectively impair cellular energy metabolism. To identify a common cellular response to RC disease, systems biology level transcriptome investigations were performed in human RC disease skeletal muscle and fibroblasts. Global transcriptional and post-transcriptional dysregulation in a tissue-specific fashion was identified across diverse RC complex and genetic etiologies. RC disease muscle was characterized by decreased transcription of cytosolic ribosomal proteins to reduce energy-intensive anabolic processes, increased transcription of mitochondrial ribosomal proteins, shortened 5'-UTRs to improve translational efficiency, and stabilization of 3'-UTRs containing AU-rich elements. These same modifications in a reversed direction typified RC disease fibroblasts. RC disease also dysregulated transcriptional networks related to basic nutrient-sensing signaling pathways, which collectively mediate many aspects of tissue-specific cellular responses to primary RC disease. These findings support the utility of a systems biology approach to improve mechanistic understanding of mitochondrial RC disease.
Primary respiratory chain disease causes tissue-specific dysregulation of the global transcriptome and nutrient-sensing signaling network.
Sex, Age, Specimen part
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Metabolic pathway profiling of mitochondrial respiratory chain mutants in C. elegans.
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View SamplesMicroarray expression profiling has become a valuable tool in the evaluation of the genetic consequences of metabolic disease. Although 3-biased gene expression microarray platforms were the first generation to have widespread availability, newer platforms are gradually emerging that have more up-to-date content and/or higher cost efficiency. Deciphering the relative strengths and weaknesses of these various platforms for metabolic pathway level analyses can be daunting. We sought to determine the practical strengths and weaknesses of four leading commercially-available expression array platforms relative to biologic investigations, as well as assess the feasibility of cross-platform data integration for purposes of biochemical pathway analyses. METHODS: Liver RNA from B6.Alb/cre,Pdss2loxP/loxP mice having primary Coenzyme Q deficiency was extracted either at baseline or following treatment with an antioxidant/antihyperlipidemic agent, probucol. Target RNA samples were prepared and hybridized to Affymetrix 430 2.0, Affymetrix Gene 1.0 ST, Affymetrix Exon 1.0 ST, and Illumina Mouse WG-6 expression arrays. Probes on all platforms were re-mapped to coding sequences in the current version of the mouse genome. Data processing and statistical analysis were performed by R/Bioconductor functions, and pathway analyses were carried out by KEGG Atlas and GSEA. RESULTS: Expression measurements were generally consistent across platforms. However, intensive probe-level comparison suggested that differences in probe locations were a major source of inter-platform variance. In addition, genes expressed at low or intermediate levels had lower inter-platform reproducibility than highly expressed genes. All platforms showed similar patterns of differential expression between sample groups, with steroid biosynthesis consistently identified as the most down-regulated metabolic pathway by probucol treatment. CONCLUSIONS: This work offers a timely guide for metabolic disease investigators to enable informed end-user decisions regarding choice of expression microarray platform best-suited to specific research project goals. Successful cross-platform integration of biochemical pathway expression data is also demonstrated, especially for well-annotated and highly-expressed genes. However, integration of gene-level expression data is limited by individual platform probe design and the expression level of target genes. Cross-platform analyses of biochemical pathway data will require additional data processing and novel computational bioinformatics tools to address unique statistical challenges.
Cross-platform expression microarray performance in a mouse model of mitochondrial disease therapy.
Sex, Age, Specimen part, Treatment
View SamplesUtilizing C. elegans as a model of mitochondrial dysfunction provides insight into cellular adaptations which occur as a consequence of genetic alterations causative of human disease. We characterized genome-wide expression profiles of hypomorhpic C. elegans mutants in nuclear-encoded subunits of respiratory chain complexes I, II and III.
Metabolic pathway profiling of mitochondrial respiratory chain mutants in C. elegans.
No sample metadata fields
View SamplesUtilizing C. elegans as a model of mitochondrial dysfunction provides insight into cellular adaptations which occur as a consequence of genetic alterations causative of human disease. We characterized genome-wide expression profiles of hypomorphic C. ele
Metabolic pathway profiling of mitochondrial respiratory chain mutants in C. elegans.
No sample metadata fields
View SamplesThe forkhead transcription factor, Foxp3, is pivotal to the development and function of CD4+CD25+ T regulatory (Treg) cells that limit autoimmunity and maintain immune homeostasis. Previous data indicated that many of the functions of Foxp3 are controlled by the acetylation of several lysines within the forkhead domain. We now show that mutation of each of two lysines within the forkhead domain of Foxp3, lysine at position 382 (K17) and lysine at position 393 (K18), impaired Treg suppressive function in vivo and in vitro. Lysine mutations also decreased Treg expression of multiple functionally important Foxp3-regulated genes, and inhibited the promoter remodeling of target genes (CTLA-4 and IL-2) without affecting Foxp3 expression level. These data point to the need for a further understanding of the effects of various post-translational modifications on Foxp3 function. Our studies also provide a rationale for developing small molecule inhibitors of such post-translational modifications so as to regulate Foxp3+ Treg function clinically.
No associated publication
Specimen part
View SamplesT-regulatory (Treg) cells are important to immune homeostasis, and Treg cell deficiency or dysfunction leads to autoimmune disease. An histone/protein acetyltransferase (HAT), p300, was recently found important for Treg function and stability, but further insights into the mechanisms by which p300 or other HATs affect Treg biology are needed. Here we show that CBP, a p300 paralog, is also important in controlling Treg function and stability. Thus, while mice with Treg-specific deletion of CBP or p300 developed minimal autoimmune disease, the combined deletion of CBP and p300 led to fatal autoimmunity by 3-4 weeks of age. The effects of CBP and p300 deletion on Treg development are dose-dependent, and involve multiple mechanisms. CBP and p300 cooperate with several key Treg transcription factors that act on the Foxp3 promoter to promote Foxp3 production. CBP and p300 also act on the Foxp3 CNS2 region to maintain Treg stability in inflammatory environments by regulating pCREB function and GATA3 expression, respectively. Lastly, CBP and p300 regulate the epigenetic status and function of Foxp3. Our findings provide insights into how HATs orchestrate multiple aspects of Treg development and function, and identify overlapping but also discrete activities for p300 and CBP in control of Treg cells.
Two histone/protein acetyltransferases, CBP and p300, are indispensable for Foxp3+ T-regulatory cell development and function.
No sample metadata fields
View SamplesSirtuin-1 (Sirt1), a class III histone/protein deacetylase is central to cellular metabolism, stress responses and aging, but its contributions to various host immune functions have been little investigated. To study the role of Sirt1 in T-cell functions, we undertook targeted deletions by mating mice with a floxed Sirt1 gene to mice expressing CD4-cre or Foxp3-cre recombinase, respectively. We found that Sirt1 deletion left conventional T-effector cell activation, proliferation and cytokine production largely unaltered. However, Sirt1 targeting promoted the expression and acetylation of Foxp3, a key transcription factor in T-regulatory (Treg) cells, and increased Treg suppressive functions in vitro and in vivo. Consistent with these data, mice with targeted deletions of Sirt1 in either CD4+ T-cells or Foxp3+ Treg cells exhibited prolonged survival of MHC-mismatched cardiac allografts. Allografts in Sirt1 targeted recipients showed long-term preservation of myocardial histology and infiltration by Foxp3+ Treg cells. Comparable results were seen in wild-type allograft recipients treated with Sirt1 inhibitors, such as EX-527 and splitomicin. Hence, Sirt1 may inhibit Treg functions and its targeting may have therapeutic value in autoimmunity and transplantation.
Sirtuin-1 targeting promotes Foxp3+ T-regulatory cell function and prolongs allograft survival.
Specimen part
View SamplesWe investigated the role of DNMT1 in immune homeostasis by generating mice lacking DNMT1 in Foxp3+ T-regulatory (Treg) cells. These mice showed decreased peripheral Foxp3+ Tregs, complete loss of Foxp3+ Treg suppressive functions in vitro and in vivo, and died from autoimmunity by 3-4 weeks unless they received perinatal transfer of wild-type Tregs that prolonged their survival. Methylation of CpG-sites in the TSDR region of Foxp3 was unaffected by DNMT1 deletion, but microarray revealed more >500 proinflammatory and other genes were upregulated in DNMT1-/- Tregs. CD4-Cre-mediated DNMT1 deletion showed inability of conventional T cells to convert to Foxp3+ Treg under appropriate polarizing conditions. Hence, DNMT1 is absolutely necessary for maintenance of the gene program required for normal Treg development and function.
Foxp3+ T-regulatory cells require DNA methyltransferase 1 expression to prevent development of lethal autoimmunity.
Specimen part
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