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1.
Nat Commun ; 11(1): 4837, 2020 09 24.
Artigo em Inglês | MEDLINE | ID: mdl-32973183

RESUMO

ATP synthesis and thermogenesis are two critical outputs of mitochondrial respiration. How these outputs are regulated to balance the cellular requirement for energy and heat is largely unknown. Here we show that major facilitator superfamily domain containing 7C (MFSD7C) uncouples mitochondrial respiration to switch ATP synthesis to thermogenesis in response to heme. When heme levels are low, MSFD7C promotes ATP synthesis by interacting with components of the electron transport chain (ETC) complexes III, IV, and V, and destabilizing sarcoendoplasmic reticulum Ca2+-ATPase 2b (SERCA2b). Upon heme binding to the N-terminal domain, MFSD7C dissociates from ETC components and SERCA2b, resulting in SERCA2b stabilization and thermogenesis. The heme-regulated switch between ATP synthesis and thermogenesis enables cells to match outputs of mitochondrial respiration to their metabolic state and nutrient supply, and represents a cell intrinsic mechanism to regulate mitochondrial energy metabolism.


Assuntos
Trifosfato de Adenosina/metabolismo , Heme/metabolismo , Proteínas de Membrana Transportadoras/metabolismo , Mitocôndrias/metabolismo , Receptores Virais/metabolismo , Termogênese/fisiologia , Animais , Deficiência de Citocromo-c Oxidase , Complexo III da Cadeia de Transporte de Elétrons , Complexo IV da Cadeia de Transporte de Elétrons , Metabolismo Energético/fisiologia , Técnicas de Inativação de Genes , Células HEK293 , Humanos , Proteínas de Membrana Transportadoras/genética , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Membranas Mitocondriais/metabolismo , Domínios Proteicos , Receptores Virais/genética , ATPases Transportadoras de Cálcio do Retículo Sarcoplasmático/metabolismo , Transdução de Sinais , Células THP-1
2.
Nat Commun ; 11(1): 4866, 2020 09 25.
Artigo em Inglês | MEDLINE | ID: mdl-32978391

RESUMO

Mitochondria house evolutionarily conserved pathways of carbon and nitrogen metabolism that drive cellular energy production. Mitochondrial bioenergetics is regulated by calcium uptake through the mitochondrial calcium uniporter (MCU), a multi-protein complex whose assembly in the inner mitochondrial membrane is facilitated by the scaffold factor MCUR1. Intriguingly, many fungi that lack MCU contain MCUR1 homologs, suggesting alternate functions. Herein, we characterize Saccharomyces cerevisiae homologs Put6 and Put7 of MCUR1 as regulators of mitochondrial proline metabolism. Put6 and Put7 are tethered to the inner mitochondrial membrane in a large hetero-oligomeric complex, whose abundance is regulated by proline. Loss of this complex perturbs mitochondrial proline homeostasis and cellular redox balance. Yeast cells lacking either Put6 or Put7 exhibit a pronounced defect in proline utilization, which can be corrected by the heterologous expression of human MCUR1. Our work uncovers an unexpected role of MCUR1 homologs in mitochondrial proline metabolism.


Assuntos
Proteínas de Membrana/metabolismo , Mitocôndrias/metabolismo , Proteínas Mitocondriais/metabolismo , Prolina/metabolismo , Saccharomyces cerevisiae/metabolismo , Canais de Cálcio , Regulação Fúngica da Expressão Gênica , Genes Fúngicos/genética , Homeostase , Humanos , Proteínas de Membrana/genética , Redes e Vias Metabólicas/genética , Membranas Mitocondriais/metabolismo , Proteínas Mitocondriais/genética , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/crescimento & desenvolvimento , Transcriptoma
3.
Nat Commun ; 11(1): 4471, 2020 09 08.
Artigo em Inglês | MEDLINE | ID: mdl-32901010

RESUMO

A human cell contains hundreds to thousands of mitochondrial DNA (mtDNA) packaged into nucleoids. Currently, the segregation and allocation of nucleoids are thought to be passively determined by mitochondrial fusion and division. Here we provide evidence, using live-cell super-resolution imaging, that nucleoids can be actively transported via KIF5B-driven mitochondrial dynamic tubulation (MDT) activities that predominantly occur at the ER-mitochondria contact sites (EMCS). We further demonstrate that a mitochondrial inner membrane protein complex MICOS links nucleoids to Miro1, a KIF5B receptor on mitochondria, at the EMCS. We show that such active transportation is a mechanism essential for the proper distribution of nucleoids in the peripheral zone of the cell. Together, our work identifies an active transportation mechanism of nucleoids, with EMCS serving as a key platform for the interplay of nucleoids, MICOS, Miro1, and KIF5B to coordinate nucleoids segregation and transportation.


Assuntos
DNA Mitocondrial/metabolismo , Retículo Endoplasmático/metabolismo , Mitocôndrias/metabolismo , Dinâmica Mitocondrial/fisiologia , Animais , Transporte Biológico Ativo , Células COS , Células Cultivadas , Chlorocebus aethiops , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Células HEK293 , Humanos , Cinesina/metabolismo , Proteínas de Membrana Transportadoras/genética , Proteínas de Membrana Transportadoras/metabolismo , Camundongos , Membranas Mitocondriais/metabolismo , Proteínas Mitocondriais/genética , Proteínas Mitocondriais/metabolismo , Modelos Biológicos , Ratos , Receptores de Superfície Celular/genética , Receptores de Superfície Celular/metabolismo , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Transfecção , Proteínas rho de Ligação ao GTP/metabolismo
4.
Proc Natl Acad Sci U S A ; 117(34): 20607-20614, 2020 08 25.
Artigo em Inglês | MEDLINE | ID: mdl-32788360

RESUMO

The mitochondrial contact site and cristae organizing system (MICOS) is a multisubunit protein complex that is essential for the proper architecture of the mitochondrial inner membrane. MICOS plays a key role in establishing and maintaining crista junctions, tubular or slit-like structures that connect the cristae membrane with the inner boundary membrane, thereby ensuring a contiguous inner membrane. MICOS is enriched at crista junctions, but the detailed distribution of its subunits around crista junctions is unclear because such small length scales are inaccessible with established fluorescence microscopy. By targeting individually activated fluorophores with an excitation beam featuring a central zero-intensity point, the nanoscopy method called MINFLUX delivers single-digit nanometer-scale three-dimensional (3D) resolution and localization precision. We employed MINFLUX nanoscopy to investigate the submitochondrial localization of the core MICOS subunit Mic60 in relation to two other MICOS proteins, Mic10 and Mic19. We demonstrate that dual-color 3D MINFLUX nanoscopy is applicable to the imaging of organellar substructures, yielding a 3D localization precision of ∼5 nm in human mitochondria. This isotropic precision facilitated the development of an analysis framework that assigns localization clouds to individual molecules, thus eliminating a source of bias when drawing quantitative conclusions from single-molecule localization microscopy data. MINFLUX recordings of Mic60 indicate ringlike arrangements of multiple molecules with a diameter of 40 to 50 nm, suggesting that Mic60 surrounds individual crista junctions. Statistical analysis of dual-color MINFLUX images demonstrates that Mic19 is generally in close proximity to Mic60, whereas the spatial coordination of Mic10 with Mic60 is less regular, suggesting structural heterogeneity of MICOS.


Assuntos
Proteínas de Membrana/metabolismo , Mitocôndrias/metabolismo , Membranas Mitocondriais/metabolismo , Proteínas Mitocondriais/metabolismo , Células HeLa , Humanos , Microscopia de Fluorescência/métodos
5.
Nat Commun ; 11(1): 3830, 2020 07 31.
Artigo em Inglês | MEDLINE | ID: mdl-32737313

RESUMO

The mammalian mitochondrial ribosome (mitoribosome) and its associated translational factors have evolved to accommodate greater participation of proteins in mitochondrial translation. Here we present the 2.68-3.96 Å cryo-EM structures of the human 55S mitoribosome in complex with the human mitochondrial elongation factor G1 (EF-G1mt) in three distinct conformational states, including an intermediate state and a post-translocational state. These structures reveal the role of several mitochondria-specific (mito-specific) mitoribosomal proteins (MRPs) and a mito-specific segment of EF-G1mt in mitochondrial tRNA (tRNAmt) translocation. In particular, the mito-specific C-terminal extension in EF-G1mt is directly involved in translocation of the acceptor arm of the A-site tRNAmt. In addition to the ratchet-like and independent head-swiveling motions exhibited by the small mitoribosomal subunit, we discover significant conformational changes in MRP mL45 at the nascent polypeptide-exit site within the large mitoribosomal subunit that could be critical for tethering of the elongating mitoribosome onto the inner-mitochondrial membrane.


Assuntos
Mitocôndrias/metabolismo , Proteínas Mitocondriais/química , Elongação Traducional da Cadeia Peptídica , Fator G para Elongação de Peptídeos/química , RNA Mitocondrial/química , RNA de Transferência/química , Proteínas Ribossômicas/química , Ribossomos/metabolismo , Sequência de Aminoácidos , Sítios de Ligação , Microscopia Crioeletrônica , Células HEK293 , Humanos , Mitocôndrias/ultraestrutura , Membranas Mitocondriais/metabolismo , Membranas Mitocondriais/ultraestrutura , Proteínas Mitocondriais/genética , Proteínas Mitocondriais/metabolismo , Modelos Moleculares , Conformação de Ácido Nucleico , Fator G para Elongação de Peptídeos/genética , Fator G para Elongação de Peptídeos/metabolismo , Ligação Proteica , Conformação Proteica em alfa-Hélice , Conformação Proteica em Folha beta , Domínios e Motivos de Interação entre Proteínas , RNA Mitocondrial/genética , RNA Mitocondrial/metabolismo , RNA de Transferência/genética , RNA de Transferência/metabolismo , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Proteínas Ribossômicas/genética , Proteínas Ribossômicas/metabolismo , Ribossomos/ultraestrutura , Alinhamento de Sequência , Homologia de Sequência de Aminoácidos
6.
Nature ; 583(7817): 603-608, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32641832

RESUMO

Astrocytes take up glucose from the bloodstream to provide energy to the brain, thereby allowing neuronal activity and behavioural responses1-5. By contrast, astrocytes are under neuronal control through specific neurotransmitter receptors5-7. However, whether the activation of astroglial receptors can directly regulate cellular glucose metabolism to eventually modulate behavioural responses is unclear. Here we show that activation of mouse astroglial type-1 cannabinoid receptors associated with mitochondrial membranes (mtCB1) hampers the metabolism of glucose and the production of lactate in the brain, resulting in altered neuronal functions and, in turn, impaired behavioural responses in social interaction assays. Specifically, activation of astroglial mtCB1 receptors reduces the phosphorylation of the mitochondrial complex I subunit NDUFS4, which decreases the stability and activity of complex I. This leads to a reduction in the generation of reactive oxygen species by astrocytes and affects the glycolytic production of lactate through the hypoxia-inducible factor 1 pathway, eventually resulting in neuronal redox stress and impairment of behavioural responses in social interaction assays. Genetic and pharmacological correction of each of these effects abolishes the effect of cannabinoid treatment on the observed behaviour. These findings suggest that mtCB1 receptor signalling can directly regulate astroglial glucose metabolism to fine-tune neuronal activity and behaviour in mice.


Assuntos
Astrócitos/metabolismo , Metabolismo Energético , Glucose/metabolismo , Mitocôndrias/metabolismo , Receptor CB1 de Canabinoide/metabolismo , Animais , Astrócitos/citologia , Astrócitos/efeitos dos fármacos , Agonistas de Receptores de Canabinoides/farmacologia , Células Cultivadas , Dronabinol/farmacologia , Complexo I de Transporte de Elétrons/química , Complexo I de Transporte de Elétrons/metabolismo , Metabolismo Energético/efeitos dos fármacos , Glicólise/efeitos dos fármacos , Humanos , Fator 1 Induzível por Hipóxia/metabolismo , Ácido Láctico/metabolismo , Masculino , Camundongos , Mitocôndrias/efeitos dos fármacos , Membranas Mitocondriais/metabolismo , Oxirredução , Fosforilação , Espécies Reativas de Oxigênio/metabolismo , Receptor CB1 de Canabinoide/agonistas , Comportamento Social
7.
Nat Commun ; 11(1): 3301, 2020 07 03.
Artigo em Inglês | MEDLINE | ID: mdl-32620849

RESUMO

Many cellular stresses are transduced into apoptotic signals through modification or up-regulation of the BH3-only subfamily of BCL2 proteins. Through direct or indirect mechanisms, these proteins activate BAK and BAX to permeabilize the mitochondrial outer membrane. While the BH3-only proteins BIM, PUMA, and tBID have been confirmed to directly activate BAK through its canonical BH3 binding groove, whether the BH3-only proteins BMF, HRK or BIK can directly activate BAK is less clear. Here we show that BMF and HRK bind and directly activate BAK. Through NMR studies, site-directed mutagenesis, and advanced molecular dynamics simulations, we also find that BAK activation by BMF and possibly HRK involves a previously unrecognized binding groove formed by BAK α4, α6, and α7 helices. Alterations in this groove decrease the ability of BMF and HRK to bind BAK, permeabilize membranes and induce apoptosis, suggesting a potential role for this BH3-binding site in BAK activation.


Assuntos
Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Proteínas Reguladoras de Apoptose/metabolismo , Proteína Killer-Antagonista Homóloga a bcl-2/metabolismo , Proteínas Adaptadoras de Transdução de Sinal/química , Proteínas Adaptadoras de Transdução de Sinal/genética , Sequência de Aminoácidos , Animais , Proteínas Reguladoras de Apoptose/química , Proteínas Reguladoras de Apoptose/genética , Sítios de Ligação/genética , Células Cultivadas , Humanos , Células Jurkat , Espectroscopia de Ressonância Magnética , Camundongos Knockout , Membranas Mitocondriais/metabolismo , Simulação de Dinâmica Molecular , Mutação , Ligação Proteica , Domínios Proteicos , Proteínas Proto-Oncogênicas c-bcl-2/química , Proteínas Proto-Oncogênicas c-bcl-2/genética , Proteínas Proto-Oncogênicas c-bcl-2/metabolismo , Homologia de Sequência de Aminoácidos , Proteína Killer-Antagonista Homóloga a bcl-2/química , Proteína Killer-Antagonista Homóloga a bcl-2/genética
8.
Nat Commun ; 11(1): 3290, 2020 07 03.
Artigo em Inglês | MEDLINE | ID: mdl-32620929

RESUMO

In mitochondria, ß-barrel outer membrane proteins mediate protein import, metabolite transport, lipid transport, and biogenesis. The Sorting and Assembly Machinery (SAM) complex consists of three proteins that assemble as a 1:1:1 complex to fold ß-barrel proteins and insert them into the mitochondrial outer membrane. We report cryoEM structures of the SAM complex from Myceliophthora thermophila, which show that Sam50 forms a 16-stranded transmembrane ß-barrel with a single polypeptide-transport-associated (POTRA) domain extending into the intermembrane space. Sam35 and Sam37 are located on the cytosolic side of the outer membrane, with Sam35 capping Sam50, and Sam37 interacting extensively with Sam35. Sam35 and Sam37 each adopt a GST-like fold, with no functional, structural, or sequence similarity to their bacterial counterparts. Structural analysis shows how the Sam50 ß-barrel opens a lateral gate to accommodate its substrates.


Assuntos
Mitocôndrias/metabolismo , Proteínas de Transporte da Membrana Mitocondrial/metabolismo , Membranas Mitocondriais/metabolismo , Biossíntese de Proteínas , Saccharomyces cerevisiae/metabolismo , Sequência de Aminoácidos , Microscopia Crioeletrônica , Detergentes/química , Proteínas Fúngicas/química , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Mitocôndrias/genética , Mitocôndrias/ultraestrutura , Proteínas de Transporte da Membrana Mitocondrial/química , Proteínas de Transporte da Membrana Mitocondrial/genética , Complexos Multiproteicos/química , Complexos Multiproteicos/metabolismo , Complexos Multiproteicos/ultraestrutura , Conformação Proteica , Dobramento de Proteína , Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/química , Proteínas de Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/metabolismo , Homologia de Sequência de Aminoácidos , Sordariales/genética , Sordariales/metabolismo
9.
Parasitol Res ; 119(9): 2943-2954, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32607710

RESUMO

Trypanosomatidae is a family of unicellular parasites belonging to the phylum Euglenozoa, which are causative agents in high impact human diseases such as Leishmaniasis, Chagas disease and African sleeping sickness. The impact on human health and local economies, together with a lack of satisfactory chemotherapeutic treatments and effective vaccines, justifies stringent research efforts to search for new disease therapies. Here, we present in vitro trypanocidal activity data and mode of action data, repositioning leishmanicidal [1,2,3]Triazolo[1,5-a]pyridinium salts against Trypanosoma cruzi, the aetiological agent of Chagas disease. This disease is one of the most neglected tropical diseases and is a major public health issue in Central and South America. The disease affects approximately 6-7 million people and is widespread due to increased migratory movements. We screened a suite of leishmanicidal [1,2,3]Triazolo[1,5-a]pyridinium salt compounds, of which compounds 13, 20 and 21 were identified as trypanocidal drugs. These compounds caused cell death in a mitochondrion-dependent manner through a bioenergetic collapse. Moreover, compounds 13 and 20 showed a remarkable inhibition of iron superoxide dismutase activity of T. cruzi, a key enzyme in the protection from the damage produced by oxidative stress.


Assuntos
Doença de Chagas/tratamento farmacológico , Compostos de Piridínio/farmacologia , Tripanossomicidas/farmacologia , Trypanosoma cruzi/efeitos dos fármacos , Animais , Morte Celular/efeitos dos fármacos , Reposicionamento de Medicamentos , Humanos , Leishmaniose/tratamento farmacológico , Membranas Mitocondriais/metabolismo , Estresse Oxidativo/efeitos dos fármacos , América do Sul , Superóxido Dismutase/metabolismo , Tripanossomíase Africana/tratamento farmacológico
10.
Mol Cell ; 79(1): 68-83.e7, 2020 07 02.
Artigo em Inglês | MEDLINE | ID: mdl-32533918

RESUMO

BAX is a pro-apoptotic protein that transforms from a cytosolic monomer into a toxic oligomer that permeabilizes the mitochondrial outer membrane. How BAX monomers assemble into a higher-order conformation, and the structural determinants essential to membrane permeabilization, remain a mechanistic mystery. A key hurdle has been the inability to generate a homogeneous BAX oligomer (BAXO) for analysis. Here, we report the production and characterization of a full-length BAXO that recapitulates physiologic BAX activation. Multidisciplinary studies revealed striking conformational consequences of oligomerization and insight into the macromolecular structure of oligomeric BAX. Importantly, BAXO enabled the assignment of specific roles to particular residues and α helices that mediate individual steps of the BAX activation pathway, including unexpected functionalities of BAX α6 and α9 in driving membrane disruption. Our results provide the first glimpse of a full-length and functional BAXO, revealing structural requirements for the elusive execution phase of mitochondrial apoptosis.


Assuntos
Apoptose , Mitocôndrias/patologia , Membranas Mitocondriais/metabolismo , Multimerização Proteica , Proteína X Associada a bcl-2/química , Proteína X Associada a bcl-2/metabolismo , Animais , Transporte Biológico , Permeabilidade da Membrana Celular , Citosol/metabolismo , Humanos , Camundongos , Mitocôndrias/metabolismo , Modelos Moleculares , Conformação Proteica , Proteínas Proto-Oncogênicas c-fos
11.
Proc Natl Acad Sci U S A ; 117(27): 15684-15693, 2020 07 07.
Artigo em Inglês | MEDLINE | ID: mdl-32571921

RESUMO

Mitochondria are known to play an essential role in photoreceptor function and survival that enables normal vision. Within photoreceptors, mitochondria are elongated and extend most of the inner-segment length, where they supply energy for protein synthesis and the phototransduction machinery in the outer segment, as well as acting as a calcium store. Here, we examined the arrangement of the mitochondria within the inner segment in detail using three-dimensional (3D) electron microscopy techniques and show they are tethered to the plasma membrane in a highly specialized arrangement. Remarkably, mitochondria and their cristae openings align with those of neighboring inner segments. The pathway by which photoreceptors meet their high energy demands is not fully understood. We propose this to be a mechanism to share metabolites and assist in maintaining homeostasis across the photoreceptor cell layer. In the extracellular space between photoreceptors, Müller glial processes were identified. Due to the often close proximity to the inner-segment mitochondria, they may, too, play a role in the inner-segment mitochondrial arrangement as well as metabolite shuttling. OPA1 is an important factor in mitochondrial homeostasis, including cristae remodeling; therefore, we examined the photoreceptors of a heterozygous Opa1 knockout mouse model. The cristae structure in the Opa1 +/- photoreceptors was not greatly affected, but the mitochondria were enlarged and had reduced alignment to neighboring inner-segment mitochondria. This indicates the importance of key regulators in maintaining this specialized photoreceptor mitochondrial arrangement.


Assuntos
GTP Fosfo-Hidrolases/genética , Mitocôndrias/genética , Membranas Mitocondriais/ultraestrutura , Visão Ocular/genética , Animais , Membrana Celular/genética , Membrana Celular/ultraestrutura , Células Ependimogliais/metabolismo , Células Ependimogliais/ultraestrutura , Humanos , Camundongos , Microscopia Eletrônica , Mitocôndrias/ultraestrutura , Membranas Mitocondriais/metabolismo , Células Fotorreceptoras/ultraestrutura , Visão Ocular/fisiologia
12.
PLoS One ; 15(6): e0234653, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32579577

RESUMO

We previously demonstrated that hexokinase II (HK2) dissociation from mitochondria during cardiac ischemia correlates with cytochrome c (cyt-c) loss, oxidative stress and subsequent reperfusion injury. However, whether HK2 release is the primary signal mediating this ischemia-induced mitochondrial dysfunction was not established. To investigate this, we studied the effects of dissociating HK2 from isolated heart mitochondria. Mitochondria isolated from Langendorff-perfused rat hearts before and after 30 min global ischemia ± ischemic preconditioning (IPC) were subject to in vitro dissociation of HK2 by incubation with glucose-6-phosphate at pH 6.3. Prior HK2 dissociation from pre- or end-ischemic heart mitochondria had no effect on their cyt-c release, respiration (± ADP) or mitochondrial permeability transition pore (mPTP) opening. Inner mitochondrial membrane morphology was assessed indirectly by monitoring changes in light scattering (LS) and confirmed by transmission electron microscopy. Although no major ultrastructure differences were detected between pre- and end-ischemia mitochondria, the amplitude of changes in LS was reduced in the latter. This was prevented by IPC but not mimicked in vitro by HK2 dissociation. We also observed more Drp1, a mitochondrial fission protein, in end-ischemia mitochondria. IPC failed to prevent this increase but did decrease mitochondrial-associated dynamin 2. In vitro HK2 dissociation alone cannot replicate ischemia-induced effects on mitochondrial function implying that in vivo dissociation of HK2 modulates end-ischemia mitochondrial function indirectly perhaps involving interaction with mitochondrial fission proteins. The resulting changes in mitochondrial morphology and cristae structure would destabilize outer / inner membrane interactions, increase cyt-c release and enhance mPTP sensitivity to [Ca2+].


Assuntos
Hexoquinase/metabolismo , Mitocôndrias Cardíacas/enzimologia , Proteínas de Transporte da Membrana Mitocondrial/metabolismo , Isquemia Miocárdica/enzimologia , Animais , Respiração Celular/efeitos dos fármacos , Dinaminas/metabolismo , Glucose-6-Fosfato/farmacologia , Hemodinâmica/efeitos dos fármacos , Concentração de Íons de Hidrogênio , Precondicionamento Isquêmico , Ligantes , Masculino , Mitocôndrias Cardíacas/efeitos dos fármacos , Mitocôndrias Cardíacas/ultraestrutura , Dinâmica Mitocondrial/efeitos dos fármacos , Membranas Mitocondriais/efeitos dos fármacos , Membranas Mitocondriais/metabolismo , Isquemia Miocárdica/patologia , Ligação Proteica/efeitos dos fármacos , Ratos Wistar
13.
Food Chem ; 328: 127174, 2020 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-32492604

RESUMO

This study investigated the effect of lysosomal iron involvement in the mechanism of mitochondrial apoptosis on bovine muscle protein degradation during postmortem aging. Six crossbred cattle were studied to evaluate intracellular reactive oxygen species (ROS), antioxidant enzyme activity, lysosomal membrane stability, mitochondrial dysfunction-induced apoptosis, desmin and troponin-T degradation in both control and iron chelator desferrioxamine (DFO) groups. Results showed that lysosomal iron induced ROS accumulation and lysosomal membrane destabilization by decreasing the antioxidant enzyme activity (P < 0.05). Subsequently, lysosomal dysfunction mediated by iron increased mitochondrial membrane permeability and decreased mitochondrial membrane potential, thereby enhancing Bid and cytochrome c release and caspase-9/-3 activation (P < 0.05). Ultimately, lysosomal iron mediated lysosomal-mitochondrial apoptosis increased the postmortem bovine muscle desmin and troponin-T degradation (P < 0.05). The results indicated that lysosomal iron contributes to postmortem meat tenderization through the lysosomal-mitochondrial dysfunction-induced apoptosis pathway.


Assuntos
Ferro/metabolismo , Lisossomos/metabolismo , Proteínas de Carne/metabolismo , Mitocôndrias Musculares/patologia , Membranas Mitocondriais/patologia , Animais , Apoptose/efeitos dos fármacos , Autopsia , Bovinos , Permeabilidade da Membrana Celular , Citocromos c/metabolismo , Masculino , Mitocôndrias/metabolismo , Mitocôndrias Musculares/metabolismo , Membranas Mitocondriais/metabolismo , Proteínas Musculares/metabolismo , Proteólise , Espécies Reativas de Oxigênio/metabolismo
14.
Toxicol Appl Pharmacol ; 401: 115076, 2020 08 15.
Artigo em Inglês | MEDLINE | ID: mdl-32479918

RESUMO

Statin induced myopathy (SIM) is a main deleterious effect leading to the poor treatment compliance, while the preventive or therapeutic treatments are absent. Mounting evidences demonstrated that vitamin D plays a vital role in muscle as a direct modulator. The deficiency of vitamin D was considered as a cause of muscle dysfunction, whereas the supplementation resulted in a remission. However, there is no causal proof that vitamin D supplementation rescues SIM. Here, using the mice model of simvastatin-induced myopathy, we investigated the role of vitamin D supplementation and the mechanisms associated with mitochondria. Results indicated that simvastatin administration (80 mg/kg) impaired skeletal muscle with the increased serum creatine kinase (CK) level and the declined grip strength, which were alleviated by vitamin D supplementation. Moreover, vitamin D supplementation rescued the energy metabolism dysfunction in simvastatin-treated mice gastrocnemius by reducing the abnormal aggregation of muscular glycogen and lactic acid. Mitochondrial homeostasis plays a key role in the process of energy metabolism. Thus, the mitochondrial dysfunction is a mortal damage for the highly energy-requiring tissue. In our study, the mitochondrial cristae observed under transmission electron microscope (TEM) were lytic in simvastatin-treated gastrocnemius. Interestingly, vitamin D supplementation improved the mitochondrial cristae shape by regulating the expression of mitofusin-1/2 (MFN1/2), optic atrophy 1 (OPA1) and dynamin-related protein 1 (Drp1). As expected, the mitochondrial dysfunction and oxidative stress was mitigated by vitamin D supplementation. In conclusion, these findings suggested that moderate vitamin D supplementation rescued simvastatin induced myopathy via improving the mitochondrial cristae shape and function.


Assuntos
Suplementos Nutricionais , Mitocôndrias/efeitos dos fármacos , Doenças Musculares/induzido quimicamente , Doenças Musculares/tratamento farmacológico , Sinvastatina/toxicidade , Vitamina D/administração & dosagem , Animais , Metabolismo Energético/efeitos dos fármacos , Metabolismo Energético/fisiologia , Inibidores de Hidroximetilglutaril-CoA Redutases/toxicidade , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Mitocôndrias/metabolismo , Mitocôndrias/patologia , Membranas Mitocondriais/efeitos dos fármacos , Membranas Mitocondriais/metabolismo , Membranas Mitocondriais/patologia , Doenças Musculares/metabolismo , Distribuição Aleatória
15.
Proc Natl Acad Sci U S A ; 117(22): 12109-12120, 2020 06 02.
Artigo em Inglês | MEDLINE | ID: mdl-32414919

RESUMO

The mitochondria-associated membrane (MAM) has emerged as a cellular signaling hub regulating various cellular processes. However, its molecular components remain unclear owing to lack of reliable methods to purify the intact MAM proteome in a physiological context. Here, we introduce Contact-ID, a split-pair system of BioID with strong activity, for identification of the MAM proteome in live cells. Contact-ID specifically labeled proteins proximal to the contact sites of the endoplasmic reticulum (ER) and mitochondria, and thereby identified 115 MAM-specific proteins. The identified MAM proteins were largely annotated with the outer mitochondrial membrane (OMM) and ER membrane proteins with MAM-related functions: e.g., FKBP8, an OMM protein, facilitated MAM formation and local calcium transport at the MAM. Furthermore, the definitive identification of biotinylation sites revealed membrane topologies of 85 integral membrane proteins. Contact-ID revealed regulatory proteins for MAM formation and could be reliably utilized to profile the proteome at any organelle-membrane contact sites in live cells.


Assuntos
Retículo Endoplasmático/metabolismo , Proteínas de Membrana/metabolismo , Mitocôndrias/metabolismo , Membranas Mitocondriais/metabolismo , Proteoma/análise , Proteínas de Ligação a Tacrolimo/metabolismo , Cálcio/metabolismo , Humanos , Biogênese de Organelas , Proteoma/metabolismo , Transdução de Sinais
16.
Proc Natl Acad Sci U S A ; 117(22): 12143-12154, 2020 06 02.
Artigo em Inglês | MEDLINE | ID: mdl-32424107

RESUMO

Proximity labeling catalyzed by promiscuous enzymes, such as TurboID, have enabled the proteomic analysis of subcellular regions difficult or impossible to access by conventional fractionation-based approaches. Yet some cellular regions, such as organelle contact sites, remain out of reach for current PL methods. To address this limitation, we split the enzyme TurboID into two inactive fragments that recombine when driven together by a protein-protein interaction or membrane-membrane apposition. At endoplasmic reticulum-mitochondria contact sites, reconstituted TurboID catalyzed spatially restricted biotinylation, enabling the enrichment and identification of >100 endogenous proteins, including many not previously linked to endoplasmic reticulum-mitochondria contacts. We validated eight candidates by biochemical fractionation and overexpression imaging. Overall, split-TurboID is a versatile tool for conditional and spatially specific proximity labeling in cells.


Assuntos
Retículo Endoplasmático/metabolismo , Proteínas de Membrana/metabolismo , Mitocôndrias/metabolismo , Membranas Mitocondriais/metabolismo , Proteoma/análise , Biotinilação , Células HEK293 , Humanos , Proteoma/metabolismo , Coloração e Rotulagem
17.
Nat Commun ; 11(1): 2355, 2020 05 12.
Artigo em Inglês | MEDLINE | ID: mdl-32398688

RESUMO

Correct intracellular distribution of proteins is critical for the function of eukaryotic cells. Certain proteins are targeted to more than one cellular compartment, e.g. to mitochondria and peroxisomes. The protein phosphatase Ptc5 from Saccharomyces cerevisiae contains an N-terminal mitochondrial presequence followed by a transmembrane domain, and has been detected in the mitochondrial intermembrane space. Here we show mitochondrial transit of Ptc5 to peroxisomes. Translocation of Ptc5 to peroxisomes depended both on the C-terminal peroxisomal targeting signal (PTS1) and N-terminal cleavage by the mitochondrial inner membrane peptidase complex. Indirect targeting of Ptc5 to peroxisomes prevented deleterious effects of its phosphatase activity in the cytosol. Sorting of Ptc5 involves simultaneous interaction with import machineries of both organelles. We identify additional mitochondrial proteins with PTS1, which localize in both organelles and can increase their physical association. Thus, a tug-of-war-like mechanism can influence the interaction and communication of two cellular compartments.


Assuntos
Mitocôndrias/metabolismo , Peroxissomos/metabolismo , Proteína Fosfatase 2C/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/metabolismo , Membranas Mitocondriais/metabolismo , Proteínas Mitocondriais/metabolismo , Sinais Direcionadores de Proteínas , Saccharomyces cerevisiae/citologia
18.
Life Sci ; 253: 117626, 2020 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-32247002

RESUMO

AIMS: Postoperative cognitive dysfunction (POCD) is a common postoperative complication that is associated with increased morbidity and mortality. However, the mechanism of pathogenesis of POCD still remains largely unknown. The aim of the study was to investigate the function and mechanism of lncRNA PCAI in POCD. MATERIALS AND METHODS: Knockdown and overexpression studies were performed to analyze the function of lncRNA PCAI in cultured BV-2 cell lines treated with LPS to mimic the neuroinflammation. Real-time PCR, western blot, ELISA were used to determine the expression level of inflammation markers. Rescue experiment was performed to prove the relationship between PCAI and SUZ12. RESULTS: We found that the expression of lncRNA PCAI was decreased with the increasing concentrations of LPS. Knockdown of lncRNA PCAI inhibited the cell death rates and attenuated the cell inflammation via ELISA and real-time PCR. Besides, downregulated of lncRNA PCAI can protect the mitochondrial function via membrane potential assay. Overexpression of lncRNA PCAI can promote the cell death and inflammation response induced by LPS. We also provided mechanism study about lncRNA PCAI that negatively regulating SUZ12. Rescue experiment also verified the results. CONCLUSION: We performed comprehensive study of functional analysis of lncRNA PCAI in POCD and proved its mechanism, which negatively regulate SUZ12. Our study provided new clues for the clinical intervention and targets for POCD.


Assuntos
Disfunção Cognitiva/etiologia , Hipocampo/metabolismo , Inflamação/metabolismo , Complicações Cognitivas Pós-Operatórias/prevenção & controle , Complicações Pós-Operatórias/prevenção & controle , RNA Longo não Codificante/genética , Animais , Linhagem Celular , Regulação da Expressão Gênica , Técnicas de Silenciamento de Genes , Inflamação/patologia , Camundongos , Membranas Mitocondriais/metabolismo , Complexo Repressor Polycomb 2/genética , Substâncias Protetoras/metabolismo , Substâncias Protetoras/farmacologia
19.
Metabolism ; 107: 154227, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32275974

RESUMO

OBJECTIVE: L5, a highly electronegative subtype of low-density lipoprotein (LDL), is likely associated with the development of atherosclerosis and cardiovascular diseases. Normal LDL is composed mainly of apolipoprotein (Apo) B, but L5 has additional proteins such as ApoE. We previously demonstrated that L5 induces endothelial cell senescence by increasing mitochondrial reactive oxygen species. In the present study, we examined the effect of L5 on mitochondrial function in cardiomyocytes. METHODS: We used the Seahorse XF24 extracellular flux analyzer to examine the effect of L5 and its components on mitochondrial energy production. The effects of L5 on mitochondrial morphology were examined by immunofluorescence using MitoTracker Green FM and the corresponding probes in H9c2 cardiomyoblasts. Mitochondrial permeability was assessed by using a calcium-induced swelling assay with a voltage-dependent anion-selective channel (VDAC) inhibitor to determine VDAC-dependence both in vitro and in vivo. L5 without ApoE, referred to as △L5, was used to clarify the role of ApoE in L5-induced mitochondrial dysfunction. RESULTS: L5 not only significantly decreased basal (P < 0.05) and maximal respiration (P < 0.01) but also reduced spare respiratory capacity (P < 0.01) in H9c2 cells. Additionally, L5 caused phosphorylation of Drp1 and mitochondrial fission. Recombinant ApoE mimicked the mitochondrial effects of L5, but △L5 did not cause similar effects. After entering cells, ApoE on L5 colocalized with mitochondrial VDAC and caused mitochondria swelling both in vitro and in vivo. This effect was also seen with recombinant ApoE but not △L5. CONCLUSIONS: ApoE may play an important role in electronegative LDL-induced mitochondrial dysfunction through the opening of the mitochondrial permeability transition pore via the interaction of ApoE and VDAC.


Assuntos
Apolipoproteínas E/metabolismo , Lipoproteínas LDL/farmacologia , Doenças Mitocondriais/induzido quimicamente , Doenças Mitocondriais/metabolismo , Miócitos Cardíacos/metabolismo , Animais , Linhagem Celular , Metabolismo Energético/efeitos dos fármacos , Humanos , Técnicas In Vitro , Lipoproteínas LDL/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Membranas Mitocondriais/metabolismo , Dilatação Mitocondrial/efeitos dos fármacos , Miócitos Cardíacos/efeitos dos fármacos , Consumo de Oxigênio/efeitos dos fármacos , Espécies Reativas de Oxigênio
20.
J Dairy Sci ; 103(6): 5561-5574, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32278565

RESUMO

Inflammation is critical in the progression from benign hepatic lipidosis to pathological hepatic steatosis. The objective of this study was to examine the potential role of the outer mitochondrial membrane protein mitofusin 2 (MFN2) in the etiology of hepatic steatosis in dairy cows during early lactation. Using a nested case-control design, we compared blood and liver samples from 10 healthy cows and 10 age-matched cows with moderate fatty liver. Cows with moderate fatty liver had high liver triacylglycerols, elevated plasma concentrations of free fatty acids (FFA) and ß-hydroxybutyrate, and low concentrations of glucose. Cows with moderate fatty liver had overactivated inflammatory pathways in the liver, as indicated by increased abundance of phosphorylated nuclear factor κB (NF-κB) p65, NLR family pyrin domain containing 3 (NLRP3) and caspase-1 inflammasome protein, and elevated plasma concentrations and hepatic mRNA abundance of their molecular targets IL-1ß, IL-6, and tumor necrosis factor α (TNF-α). In the cell culture model, we were able to replicate our findings in cows with moderate fatty liver: 1.2 mM exogenous FFA decreased the abundance of MFN2 and upregulated phosphorylation levels of the inhibitor of NF-κB (IκB) α and NF-κB p65, the IκB kinase ß activity, and the abundance of NLRP3, caspase-1, IL-1ß, IL-6, and TNF-α. Whereas MFN2 knockdown potentiated the FFA-induced activation of these inflammatory pathways, overexpression of MFN2 attenuated the detrimental effect of excess exogenous FFA by improving mitochondrial function and decreasing the release of reactive oxygen species, suggesting that MFN2 may be a potential therapeutic target for FFA-induced hepatic inflammation in dairy cows during early lactation.


Assuntos
Doenças dos Bovinos/prevenção & controle , Ácidos Graxos não Esterificados/efeitos adversos , Fígado Gorduroso/veterinária , GTP Fosfo-Hidrolases/antagonistas & inibidores , Inflamação/veterinária , Membranas Mitocondriais/metabolismo , Proteínas Mitocondriais/antagonistas & inibidores , Animais , Estudos de Casos e Controles , Bovinos , Ácidos Graxos não Esterificados/sangue , Fígado Gorduroso/induzido quimicamente , Fígado Gorduroso/prevenção & controle , Feminino , GTP Fosfo-Hidrolases/metabolismo , Regulação Enzimológica da Expressão Gênica/efeitos dos fármacos , Inflamação/induzido quimicamente , Inflamação/metabolismo , Lactação/efeitos dos fármacos , Proteínas Mitocondriais/metabolismo , Espécies Reativas de Oxigênio/metabolismo
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