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Mitochondrial respiratory chain dysfunction alters ER sterol sensing and mevalonate pathway activity

ABSTRACT: Mitochondrial dysfunction induces a strong adaptive retrograde signaling response, however many of the down-stream effectors remain to be discovered. Here, we studied the shared transcriptional responses to three different mitochondrial respiratory chain inhibitors in human primary skin fibroblasts using QuantSeq 3’RNA-sequencing. We found that mevalonate pathway genes were concurrently downregulated irrespective of the respiratory chain complex affected. Targeted metabolomics demonstrated that impaired mitochondrial respiration at any of the three affected complexes also had functional consequences on the mevalonate pathway, reducing cholesterol precursor metabolites. A deeper study of complex I inhibition showed a reduced activity of ER-bound sterol sensing enzymes through impaired processing of the transcription factor SREBP2 and accelerated degradation of the ER cholesterol sensors SQLE and HMGCR. These adaptations of mevalonate pathway activity neither affected total intracellular cholesterol levels nor the cellular free (non-esterified) cholesterol pool. Measurement of intracellular cholesterol using the fluorescent cholesterol binding dye filipin revealed that complex I inhibition elevated cholesterol on intracellular compartments. Our study shows that mitochondrial respiratory chain dysfunction elevates intracellular free cholesterol levels and therefore attenuates the expression of mevalonate pathway enzymes, which lowers endogenous cholesterol biosynthesis, disrupting the metabolic output of the mevalonate pathway. Intracellular disturbances in cholesterol homeostasis may alter systemic cholesterol management in diseases associated with declining mitochondrial function.

ORGANISM(S): Homo sapiens

PROVIDER: GSE191034 | GEO | 2022/02/25

REPOSITORIES: GEO

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Mitochondrial respiratory chain dysfunction alters ER sterol sensing and mevalonate pathway activity

Project description:Mitochondrial respiratory chain dysfunction alters ER sterol sensing and mevalonate pathway activity

| PRJNA789485 | ENA

Transcription profiling of mouse age-related hearing loss cochlea in DBA/2J

Project description:Age-related hearing loss (AHL) is the progressive loss of auditory function with aging. The DBA/2J (DBA) mice have been used as a model of AHL and undergoes progressive, age-related hearing loss by 12 weeks of age. Here we analyzed cochlear gene expression of 7-week-old and 36-week-old DBA mice using microarrays. Auditory brainstem response (ABR) analysis confrimed that severe age-related hearing loss occured in 36-week-old mice, whereas moderate hearing loss occured in 7-week-old mice. Comprehensive gene expression analysis identified genes correlated with AHL and revealeed that 15 mitochondrial process categories, including â??mitochondrial electron transport chainâ??, â??oxidative phosphorylationâ??, â??respiratory chain complex Iâ??, â??respiratory chain complex IVâ??, and â??respiratory chain complex Vâ??, were statistically associated with AHL-correlated genes in the cochlea of 36-week-old DBA mice, and that 25 genes encoding components of the mitochondrial respiratory chain (respiratory chain complex I, IV, and V) were significantly down-regulated in the cochlea. These observations provide evidence that AHL is associated with down-regulation of genes involved in the mitochondrial respiratory chain in the cochlea of DBA mice, and suggest that mitochondrial respiratory chain dysfunction may be a key feature of AHL in mammalian cochlea. Experiment Overall Design: To determine the effects of age-related hearing loss, each 7-week-old sample (n = 3) was compared to each 36-week-old sample (n = 3), generating a total of nine pairwise comparisons. Using DAVIS and EASE, the identified genes were assign to â??GO: Biological Processâ?? categories of Gene Ontology Consortium. Furthermore, we used EASE to determine the total number of genes that were assigned to each biological process category, and to perform Fisher exact test. Quality control measures were not used. No replicates were done. Dye swap was not used.

2008-06-14 | E-GEOD-6045 | biostudies-arrayexpress

Gene expression profile of the age-related hearing loss cochlea in DBA/2J mice

Project description:Age-related hearing loss (AHL) is the progressive loss of auditory function with aging. The DBA/2J (DBA) mice have been used as a model of AHL and undergoes progressive, age-related hearing loss by 12 weeks of age. Here we analyzed cochlear gene expression of 7-week-old and 36-week-old DBA mice using microarrays. Auditory brainstem response (ABR) analysis confrimed that severe age-related hearing loss occured in 36-week-old mice, whereas moderate hearing loss occured in 7-week-old mice. Comprehensive gene expression analysis identified genes correlated with AHL and revealeed that 15 mitochondrial process categories, including “mitochondrial electron transport chain”, “oxidative phosphorylation”, “respiratory chain complex I”, “respiratory chain complex IV”, and “respiratory chain complex V”, were statistically associated with AHL-correlated genes in the cochlea of 36-week-old DBA mice, and that 25 genes encoding components of the mitochondrial respiratory chain (respiratory chain complex I, IV, and V) were significantly down-regulated in the cochlea. These observations provide evidence that AHL is associated with down-regulation of genes involved in the mitochondrial respiratory chain in the cochlea of DBA mice, and suggest that mitochondrial respiratory chain dysfunction may be a key feature of AHL in mammalian cochlea. Keywords: Disease state analysis, Time course analysis

2007-10-16 | GSE6045 | GEO

Drosophila CNS mitochondrial DNA dysfunction microarray

Project description:Mitochondrial DNA (mtDNA) encodes essential components of the respiratory chain and loss of mtDNA leads to mitochondrial dysfunction and neurodegeneration. Mitochondrial transcription factor A (TFAM) is an essential component of mtDNA replication and a regulator of mitochondrial copy number in cells. Studies have shown that TFAM knockdown leads to mitochondrial dysfunction and respiratory chain deficiencies. ATP synthase is Complex V of the mitochondrial respiratory chain. It is driven by a proton gradient between the intermembrane space and the mitochondrial matrix and generates the majority of cellular ATP. The knockdown of coupling factor 6 (Cf6), one of the components of the proton channel F0, causes dysfunction in the complex, leading to mitochondrial dysfunction and respiratory chain deficiencies. Using gene expression analysis, we aimed to investigate the effects of mtDNA dysfunction in the CNS at the molecular level.

2013-12-20 | GSE53509 | GEO

Genetic screens reveal new targetable vulnerabilities in BAP1-deficient Mesothelioma

Project description:More than half of malignant mesothelioma patients show alterations in the BAP1 tumour suppressor gene. Being a member of the Polycomb repressive deubiquitinating (PR-DUB) complex, BAP1 loss results in an altered epigenome which may create new vulnerabilities that remain largely unknown. Here we performed a CRISPR/Cas9-kinome screen in mesothelioma cells that identified two kinases in the Mevalonate/Cholesterol biosynthesis pathway. Furthermore, our analysis of chromatin, expression and genetic perturbation data in mesothelioma cells suggests a dependency on Polycomb repressive complex 2 (PRC2) mediated silencing. Pharmacological inhibition of PRC2 elevates the expression of cholesterol biosynthesis genes only in BAP1-deficient mesothelioma, thereby sensitizing these cells to the combined targeting of PRC2 and the mevalonate pathway. Finally, by subjecting autochthonous Bap1-deficient mesothelioma mice or xenografts to mevalonate pathway inhibition (Zoledronic Acid) and PRC2 inhibition (Tazemetostat), we demonstrate a potent anti-tumour effect, suggesting a targeted combination therapy for Bap1-deficient mesothelioma

2023-01-12 | GSE222376 | GEO

Differential effects of krill oil and fish oil on the hepatic transcriptome in mice

Project description:Dietary supplementation with ω-3 polyunsaturated fatty acids (ω-3 PUFAs), specifically the fatty acids docosahexaenoic acid (DHA; 22:6 ω-3) and eicosapentaenoic acid (EPA; 20:5 ω-3), is known to have beneficial health effects including improvements in glucose and lipid homeostasis and modulation of inflammation. To evaluate the efficacy of two different sources of ω-3 PUFAs, we performed gene expression profiling in the liver of mice fed diets supplemented with either fish oil or krill oil. We found that ω-3 PUFA supplements derived from a phospholipid krill fraction (krill oil) downregulated the activity of pathways involved in hepatic glucose production as well as lipid and cholesterol synthesis. The data also suggested that krill oil-supplementation increases the activity of the mitochondrial respiratory chain. Surprisingly, an equimolar dose of EPA and DHA derived from fish oil modulated fewer pathways than a krill oil-supplemented diet and did not modulate key metabolic pathways regulated by krill oil, including glucose metabolism, lipid metabolism and the mitochondrial respiratory chain. Moreover, fish oil upregulated the cholesterol synthesis pathway, which was the opposite effect of krill supplementation. Neither diet elicited changes in plasma levels of lipids, glucose or insulin, probably because the mice used in this study were young and were fed a low fat diet. Further studies of krill oil supplementation using animal models of metabolic disorders and/or diets with a higher level of fat may be required to observe these effects. Twenty-one microarrays: three diets (CO, FO, KO) x seven mice per diet x one microarray per mouse

2011-07-21 | E-GEOD-29572 | biostudies-arrayexpress

Integrative transcriptomic and proteomic analyses reveal that NLRX1 and FASTDK5 orchestrate immunometabolic fitness to fuel HIV-1 replication

Project description:We analyzed the transcriptome of CD4 T cells from HIV-1 patients and revealed that elevated oxidative phosphorylation (OXPHOS) pathway is associated with poor outcomes. Inhibition of OXPHOS by the FDA-approved drug metformin, which targets mitochondrial respiratory chain complex I, suppresses HIV-1 replication in human CD4 T cells and humanized mice. In patients, HIV-1 peak viremia positively correlates with the expression of NLRX1, a mitochondrial innate immune receptor.

2021-01-31 | GSE165841 | GEO

Endothelial-specific mitochondiral complex III KO leads to lung endothelial cell gene deregulation.

Project description:Endothelial cells (ECs) require glycolysis for proliferation and migration during angiogenesis; however, the necessity for the mitochondrial respiratory chain during angiogenesis is not known. Here we report that inhibition of respiratory chain complex III impairs proliferation, but not migration of ECs in vitro by decreasing the NAD+/NADH ratio. To determine whether mitochondrial respiration is necessary for angiogenesis in vivo, we conditionally ablate a subunit of the respiratory chain complex III (QPC) in ECs. Loss of QPC decreases respiration, resulting in diminished EC proliferation, and impairment in retinal and tumor angiogenesis. Loss of QPC does not decrease genes associated with anabolism or nucleotides levels in ECs, but diminishes amino acid levels. Our findings indicate that mitochondrial respiration is necessary for angiogenesis, and that the primary role of mitochondria in ECs is to serve as biosynthetic organelles for cell proliferation.

2018-10-26 | GSE121770 | GEO

Transcription profiling of yeast rho0 cells (complete deletion of the mitochondrial genome), in cells with either a single defective enzyme or several, vs cells after prolonged treatment with the bc1 inhibitors myxothiazol or antimycin to analyse respiratory defects

Project description:The mitochondrial respiratory chain is composed of lipoprotein complexes imbedded in the inner mitochondrial membrane. This chain of enzymes transfers electrons from NADH and FADH2, provided from divers metabolic pathways, to oxygen. It couples the transfer of electrons to the translocation of protons across the membrane. Several clinical syndromes have been associated with respiratory dysfunction caused by mitochondrial or nuclear mutations. A number of mutations in the mitochondrial genes encoding for cytochrome b (CYTB) and cytochrome oxidase (COX 1, 2 and 3) have been linked with diseases. We are using yeast mutants to characterize the deleterious effect of mutations reported in patients on the assembly and catalytic properties of the affected enzymes, and to study the impact of mutations in nuclear genes, such as OXA1, encoding for factors required for the assembly of the respiratory complexes. In this work, we monitored the effects of the mutations causing respiratory defect on the whole genome expression. We compared the change in gene expression in rho0 cells (with a complete deletion of the mitochondrial genome, and by consequence without respiratory chain), in cells with either a single defective enzyme or several, and in cells after prolonged treatment with the bc1 inhibitors myxothiazol or antimycin. The impact of the mutations on the respiratory function ranged from mild to severe. The expression of approx. 350 genes was changed in at least one mutant. Cluster analysis was performed using the Cluster program (Eisen, 1998, PNAS 95:14863). Four groups of genes were studied in more details: Group A, the most repressed genes; Group B, the most over-expressed genes; Group C, genes more repressed in rho0 and Doxa1 cells; and Group D, genes more over-expressed in Doxa1.

2009-02-20 | E-MEXP-585 | biostudies-arrayexpress

Liver adapts mitochondrial function to insulin-resistant and diabetic states in mice

Project description:Objective: To study if diabetic and insulin-resistant states lead to mitochondrial dysfunction in the liver, or alternatively, if there is adaption of mitochondrial function to these states in the long-term range. Results: High-fat diet (HFD) caused insulin resistance and severe hepatic lipid accumulation, but respiratory chain parameters were unchanged. Livers from insulin-resistant IR/IRS-1+/- mice had normal lipid contents and normal respiratory chain parameters, however showed mitochondrial uncoupling. Livers from severely hyperglycemic and hypoinsulimic, streptozotocin (STZ)-treated mice had massively depleted lipid levels, but respiratory chain abundance was unchanged. However, their mitochondria showed increased abundance and activity of the respiratory chain, which was better coupled compared to controls. Conclusions: Insulin resistance, either induced by obesity or by genetic manipulation, does not cause mitochondrial dysfunction in the liver of mice. However, severe insulin deficiency and high blood glucose levels in mice cause an enhanced performance of the respiratory chain, probably in order to maintain the high energy requirement of the unsuppressed gluconeogenesis. We performed gene expression microarray analysis on liver tissue derived from mice treated with STZ or standard diet (control).

2013-12-10 | E-GEOD-39752 | biostudies-arrayexpress

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