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Zenezini Chiozzi, R.

Publications and source records attributed to Zenezini Chiozzi, R..

4 recordsLinked to original sources

β-RA targets mitochondrial metabolism and adipogenesis, leading to therapeutic benefits against CoQ deficiency and age-related overweight

Primary mitochondrial diseases are caused by mutations in mitochondrial or nuclear genes, leading to abnormal function of specific mitochondrial pathways. Mitochondrial dysfunction is also a secondary event in more common pathophysiological conditions, such as obesity and metabolic syndrome. In both cases, the improvement and management of mitochondrial homeostasis remains challenging. Here, we show that beta-resorcylic acid ({beta}-RA), a natural phenolic compound, competes in vivo with 4-hydroxybenzoic acid, the natural precursor of Coenzyme Q biosynthesis. This leads to a decrease of demethoxyubiquinone, an intermediate metabolite of CoQ biosynthesis that is abnormally accumulated in Coq9R239X mice. As a consequence, {beta}-RA rescues the phenotype of Coq9R239X mice, a model of primary mitochondrial encephalopathy. Moreover, we observe that long-term treatment with {beta}-RA also reduces the size and content of the white adipose tissue (WAT) that is normally accumulated during aging in wild-type mice, leading to a prevention of hepatic steatosis and an increase in survival at the old stage of life. The reduction in WAT content is due to a decrease in adipogenesis, an adaptation of the mitochondrial proteome in the kidneys, and a stimulation of glycolysis and acetyl-CoA metabolism. Therefore, our results demonstrate that {beta}-RA acts through different cellular mechanisms, with effects on mitochondrial metabolism, and it may be used for the treatment of primary Coenzyme Q deficiency, overweight, and hepatic steatosis.

physiology

Molecular characterization of a complex of Apoptosis Inducing Factor 1 (AIFM1) with cytochrome c oxidase of the mitochondrial respiratory chain

Combining mass spectrometry based chemical cross-linking and complexome profiling, we analyzed the interactome of heart mitochondria. We focused on complexes of oxidative phosphorylation and found that dimeric apoptosis inducing factor 1 (AIFM1) forms a defined complex with ~10% of monomeric cytochrome c oxidase (COX), but hardly interacts with respiratory chain supercomplexes. Multiple AIFM1 inter-crosslinks engaging six different COX subunits provided structural restraints to build a detailed atomic model of the COX-AIFM12 complex. Application of two complementary proteomic approaches thus provided unexpected insight into the macromolecular organization of the mitochondrial complexome. Our structural model excludes direct electron transfer between AIFM1 and COX. Notably however, the binding site of cytochrome c remains accessible allowing formation of a ternary complex. The discovery of the previously overlooked COX-AIFM12 complex and clues provided by the structural model hint at a role of AIFM1 in OXPHOS biogenesis and in programmed cell death.

molecular biology

In-cell structures of a conserved supramolecular array at the mitochondria-cytoskeleton interface in mammalian sperm

Mitochondria-cytoskeleton interactions modulate cellular physiology by regulating mitochondrial transport, positioning, and immobilization. However, there is very little structural information defining mitochondria-cytoskeleton interfaces in any cell type. Here, we use cryo-focused ion beam milling-enabled cryo-electron tomography to image mammalian sperm, where mitochondria wrap around the ciliary cytoskeleton. We find that mitochondria are tethered to their neighbors through inter-mitochondrial linkers and are anchored to the cytoskeleton through ordered arrays on the outer mitochondrial membrane. We use subtomogram averaging to resolve in-cell structures of these arrays from three mammalian species, revealing they are conserved across species despite variations in mitochondrial dimensions and cristae organization. We find that the arrays consist of boat-shaped particles anchored on a network of membrane pores whose arrangement and dimensions are consistent with voltage dependent anion channels. Proteomics and in-cell cross-linking mass spectrometry suggest that the conserved arrays are composed of glycerol kinase-like proteins. Ordered supramolecular assemblies may serve to stabilize similar contact sites in other cell types where mitochondria need to be immobilized in specific subcellular environments, such as in muscles and neurons.

cell biology

Fasting reverses drug-resistance in hepatocellular carcinoma through p53-dependent metabolic synergism

Cancer cells voraciously consume nutrients to support their growth, exposing a metabolic vulnerability that can be therapeutically exploited. Here we show in hepatocellular carcinoma (HCC) cells, xenografts, and in patient-derived HCC organoids that fasting can synergistically sensitize resistant HCC to sorafenib. Mechanistically, sorafenib acts non-canonically as an inhibitor of mitochondrial respiration, causing resistant cells to depend on glycolysis for survival. Fasting, through reduction in glucose and impeded AKT/mTOR-signaling, prevents this Warburg shift. Regulating glucose transporter and pro-apoptotic protein expression, p53 is necessary and sufficient for the sorafenib-sensitizing effect of fasting. p53 is also crucial for fasting-mediated improvement of sorafenib efficacy in an orthotopic HCC mouse model. Together, our data suggest intermittent fasting and sorafenib as rational combination therapy for HCC with intact p53 signaling. As HCC therapy is currently severely limited by resistance, these results should instigate clinical studies aimed at improving therapy response in advanced-stage, and possibly even early-stage, HCC. HIGHLIGHTSO_LIFasting sensitizes resistant HCC xenografts and patient-derived organoids to sorafenib C_LIO_LISorafenib-mediated Warburg shift is prevented by glucose limitation upon fasting C_LIO_LIFasting synergistically improves sorafenib efficacy in non-resistant models C_LIO_LIp53 is required for synergism by regulating glucose uptake and apoptosis C_LI GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=167 SRC="FIGDIR/small/430545v2_ufig1.gif" ALT="Figure 1"> View larger version (40K): org.highwire.dtl.DTLVardef@1c0bf9org.highwire.dtl.DTLVardef@15638b4org.highwire.dtl.DTLVardef@1a4b322org.highwire.dtl.DTLVardef@1ec863a_HPS_FORMAT_FIGEXP M_FIG C_FIG

cancer biology