Project description:Mitochondria are the energy-generating hubs of the cell. In spite of considerable advances, our understanding of the factors that regulate the molecular circuits that govern mitochondrial function remains incomplete. Using a genome-wide functional screen, we have identified the poorly characterized protein Zinc finger CCCH-type containing 10 (Zc3h10) as regulator of mitochondrial physiology. We show that Zc3h10 is a nuclear RNA binding protein that controls the fate of Slc25a37 and Prelid3a mRNA transcripts, two nuclear-encoded mitochondrial proteins central for iron and cardiolipin homeostasis. Depletion of Zc3h10 results in mitochondrial dysfunction and reduced TCA cycle flux. Notably, we have identified a loss-of-function mutation of Zc3h10 in humans (Tyr105 to Cys105) that is associated with decreased mitochondrial function, increased body mass index, fat mass, fasting glucose and triglycerides. Cells from Cys105 homozygotes display alterations in Slc25a37 and Prelid3a levels and defects in mitochondrial iron and cardiolipin homeostasis that derive in mitochondrial dysfunction.
Project description:Mitochondria are the energy-generating hubs of the cell. In spite of considerable advances, our understanding of the factors that regulate the molecular circuits that govern mitochondrial function remains incomplete. Using a genome-wide functional screen, we have identified the poorly characterized protein Zinc finger CCCH-type containing 10 (Zc3h10) as regulator of mitochondrial physiology. We show that Zc3h10 is a nuclear RNA binding protein that controls the fate of Slc25a37 and Prelid3a mRNA transcripts, two nuclear-encoded mitochondrial proteins central for iron and cardiolipin homeostasis. Depletion of Zc3h10 results in mitochondrial dysfunction and reduced TCA cycle flux. Notably, we have identified a loss-of-function mutation of Zc3h10 in humans (Tyr105 to Cys105) that is associated with decreased mitochondrial function, increased body mass index, fat mass, fasting glucose and triglycerides. Cells from Cys105 homozygotes display alterations in Slc25a37 and Prelid3a levels and defects in mitochondrial iron and cardiolipin homeostasis that derive in mitochondrial dysfunction.
Project description:Mitochondria are the energy-generating hubs of the cell. In spite of considerable advances, our understanding of the factors that regulate the molecular circuits that govern mitochondrial function remains incomplete. Using a genome-wide functional screen, we have identified the poorly characterized protein Zinc finger CCCH-type containing 10 (Zc3h10) as regulator of mitochondrial physiology. We show that Zc3h10 is a nuclear RNA binding protein that controls the fate of Slc25a37 and Prelid3a mRNA transcripts, two nuclear-encoded mitochondrial proteins central for iron and cardiolipin homeostasis. Depletion of Zc3h10 results in mitochondrial dysfunction and reduced TCA cycle flux. Notably, we have identified a loss-of-function mutation of Zc3h10 in humans (Tyr105 to Cys105) that is associated with decreased mitochondrial function, increased body mass index, fat mass, fasting glucose and triglycerides. Cells from Cys105 homozygotes display alterations in Slc25a37 and Prelid3a levels and defects in mitochondrial iron and cardiolipin homeostasis that derive in mitochondrial dysfunction.
Project description:Here we show that synthesis of the mitochondrial phospholipid cardiolipin is an indispensable driver of thermogenic fat function. Cardiolipin biosynthesis is robustly induced in brown and beige adipose upon cold exposure. Mimicking this response by overexpressing cardiolipin synthase (Crls1) enhances energy consumption in mouse and human adipocytes. Crls1 deficiency diminishes mitochondrial uncoupling in brown and beige adipocytes and elicits a nuclear transcriptional response through ER stress-mediated retrograde communication. Cardiolipin depletion in brown and beige fat abolishes adipose thermogenesis and glucose uptake and renders animals strikingly insulin resistant. We further identify a rare human CRLS1 variant associated with insulin resistance and show that adipose CRLS1 levels positively correlate with insulin sensitivity. Thus, adipose cardiolipin is a powerful regulator of organismal energy homeostasis through thermogenic fat bioenergetics.
Project description:The mitochondrial inner membrane contains a unique phospholipid known as cardiolipin (CL), which stabilises the protein complexes embedded in the membrane and supports its overall structure. Recent evidence indicates that the mitochondrial ribosome may associate with the inner membrane to facilitate co-translational insertion of the hydrophobic oxidative phosphorylation (OXPHOS) proteins into the inner membrane. We generated three mutant knockout cell lines for the cardiolipin biosynthesis gene Crls1 to investigate the effects of cardiolipin loss on mitochondrial protein synthesis. Reduced CL levels caused altered mitochondrial morphology and transcriptome-wide changes that were accompanied by reduced uncoordinated mitochondrial translation rates and impaired respiratory supercomplex formation. Aberrant protein synthesis was caused by impaired formation and distribution of mitochondrial ribosomes. Reduction or loss of cardiolipin resulted in resulted in different mitochondrial and endoplasmic reticulum stress responses. We show that cardiolipin is required to stabilise the interaction of the mitochondrial ribosome with the membrane via its association with OXA1 during active translation. This interaction facilitates insertion of newly synthesised mitochondrial proteins into the inner membrane and stabilises the respiratory supercomplexes.
Project description:Mitochondria fulfill vital metabolic functions and act as crucial cellular signaling hubs integrating their metabolic status into the cellular context. Here, we show that defective cardiolipin-remodeling, upon loss of the cardiolipin acyl transferase Tafazzin, mutes HIF-1a signaling in hypoxia. Tafazzin-deficiency does not affect posttranslational HIF-1a regulation but rather HIF-1a gene-expression, a dysfunction recapitulated in iPSCs-derived cardiomyocytes from Barth Syndrome patients with Tafazzin-deficiency. RNAseq analyses confirmed drastically altered signaling in Tafazzin mutant cells. In hypoxia, Tafazzin-deficient cells display reduced production of reactive oxygen species (ROS) perturbing NF-kB activation and concomitantly HIF-1a gene-expression. In agreement, Tafazzin-deficient mice hearts display reduced HIF-1a levels and undergo maladaptive hypertrophy with heart failure in response to pressure overload challenge. We conclude that defective mitochondrial cardiolipin-remodeling dampens HIF-1a signaling through inactivation of a non-canonical signaling pathway: Lack of NF-kB activation through reduced mitochondrial ROS production diminishes HIF-1a transcription.
Project description:The study of gene expression profile of iron homeostasis-related genes using Affymetrix GeneChips in conjunction with the pathological assessment of hepatic iron content in hepatocellular carcinoma (HCC) samples offers a new strategy to understand the role of hepatic iron overload in hepatocarcinogenesis.