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1.
Biochim Biophys Acta Mol Basis Dis ; 1869(1): 166570, 2023 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-36241124

RESUMO

The proper regulation of mitochondrial function is important for cellular homeostasis. Especially, in cancer cells, dysregulation of mitochondria is associated with diverse cellular events such as metabolism, redox status, and stress responses. Mitoregulin (MTLN), a micro protein encoded by LINC00116, recently has been reported to control mitochondrial functions in skeletal muscle cells and adipocytes. However, the role of MTLN in cancer cells remains unclear. In the present study, we found that MTLN regulates membrane potential and reactive oxygen species (ROS) generation of mitochondria in breast cancer cells. Moreover, MTLN deficiency resulted in abnormal mitochondria-associated ER membranes (MAMs) formation, which is crucial for stress adaptation. Indeed, the MTLN-deficient breast cancer cells failed to successfully resolve ER (endoplasmic reticulum) stress, and cell vulnerability to ER-stress inducers was significantly enhanced by the downregulation of MTLN. In conclusion, MTLN controls stress-adaptation responses in breast cancer cells as a key regulator of mitochondria-ER harmonization, and thereby its expression level may serve as an indicator of the responsiveness of cancer cells to proteasome inhibitors.


Assuntos
Estresse do Retículo Endoplasmático , Neoplasias , Estresse do Retículo Endoplasmático/fisiologia , Membranas Mitocondriais/metabolismo , Mitocôndrias/metabolismo , Retículo Endoplasmático/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Neoplasias/metabolismo
2.
Biochim Biophys Acta Biomembr ; 1865(1): 184075, 2023 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-36273540

RESUMO

Bax is a major player in the mitochondrial pathway of apoptosis, by making the Outer Mitochondrial Membrane (OMM) permeable to various apoptogenic factors, including cytochrome c. In order to get further insight into the structure and function of Bax when it is inserted in the OMM, we attempted to reconstitute Bax in nanodiscs. Cell-free protein synthesis in the presence of nanodiscs did not yield Bax-containing nanodiscs, but it provided a simple way to purify full-length Bax without any tag. Purified wild-type Bax (BaxWT) and a constitutively active mutant (BaxP168A) displayed biochemical properties that were in line with previous characterizations following their expression in yeast and human cells followed by their reconstitution into liposomes. Both Bax variants were then reconstituted in nanodiscs. Size exclusion chromatography, dynamic light scattering and transmission electron microscopy showed that nanodiscs formed with BaxP168A were larger than nanodiscs formed with BaxWT. This was consistent with the hypothesis that BaxP168A was reconstituted in nanodiscs as an active oligomer.


Assuntos
Lipossomos , Membranas Mitocondriais , Humanos , Proteína X Associada a bcl-2/metabolismo , Membranas Mitocondriais/metabolismo , Lipossomos/química , Mitocôndrias/metabolismo , Proteínas de Transporte/metabolismo
3.
Nat Commun ; 13(1): 6704, 2022 Nov 07.
Artigo em Inglês | MEDLINE | ID: mdl-36344526

RESUMO

Understanding the mechanisms governing selective turnover of mutation-bearing mtDNA is fundamental to design therapeutic strategies against mtDNA diseases. Here, we show that specific mtDNA damage leads to an exacerbated mtDNA turnover, independent of canonical macroautophagy, but relying on lysosomal function and ATG5. Using proximity labeling and Twinkle as a nucleoid marker, we demonstrate that mtDNA damage induces membrane remodeling and endosomal recruitment in close proximity to mitochondrial nucleoid sub-compartments. Targeting of mitochondrial nucleoids is controlled by the ATAD3-SAMM50 axis, which is disrupted upon mtDNA damage. SAMM50 acts as a gatekeeper, influencing BAK clustering, controlling nucleoid release and facilitating transfer to endosomes. Here, VPS35 mediates maturation of early endosomes to late autophagy vesicles where degradation occurs. In addition, using a mouse model where mtDNA alterations cause impairment of muscle regeneration, we show that stimulation of lysosomal activity by rapamycin, selectively removes mtDNA deletions without affecting mtDNA copy number, ameliorating mitochondrial dysfunction. Taken together, our data demonstrates that upon mtDNA damage, mitochondrial nucleoids are eliminated outside the mitochondrial network through an endosomal-mitophagy pathway. With these results, we unveil the molecular players of a complex mechanism with multiple potential benefits to understand mtDNA related diseases, inherited, acquired or due to normal ageing.


Assuntos
DNA Mitocondrial , Membranas Mitocondriais , DNA Mitocondrial/genética , DNA Mitocondrial/metabolismo , Membranas Mitocondriais/metabolismo , Proteínas Mitocondriais/genética , Proteínas Mitocondriais/metabolismo , Mitocôndrias/genética , Mitocôndrias/metabolismo , Mitofagia
4.
Int J Mol Sci ; 23(21)2022 Oct 22.
Artigo em Inglês | MEDLINE | ID: mdl-36361521

RESUMO

Changes in mitochondrial membrane permeability are closely associated with mitochondria-mediated apoptosis. Antimicrobial peptides (AMPs), which have been found to enter cells to exert physiological effects, cause damage to the mitochondria. This paper reviews the molecular mechanisms of AMP-mediated apoptosis by changing the permeability of the mitochondrial membrane through three pathways: the outer mitochondrial membrane (OMM), inner mitochondrial membrane (IMM), and mitochondrial permeability transition pore (MPTP). The roles of AMPs in inducing changes in membrane permeability and apoptosis are also discussed. Combined with recent research results, the possible application prospects of AMPs are proposed to provide a theoretical reference for the development of AMPs as therapeutic agents for human diseases.


Assuntos
Peptídeos Antimicrobianos , Membranas Mitocondriais , Humanos , Membranas Mitocondriais/metabolismo , Mitocôndrias/fisiologia , Apoptose/fisiologia , Permeabilidade , Proteínas de Transporte da Membrana Mitocondrial/metabolismo
5.
Int J Mol Sci ; 23(21)2022 Nov 02.
Artigo em Inglês | MEDLINE | ID: mdl-36362175

RESUMO

The mitochondrial large-conductance calcium-activated potassium channel (mitoBKCa) is located in the inner mitochondrial membrane and seems to play a crucial role in cytoprotection. The mitoBKCa channel is regulated by many modulators, including activators, such as calcium ions and inhibitors, such as heme and its oxidized form hemin. Heme/hemin binds to the heme-binding motif (CXXCH) located between two RCK domains present in the mitochondrial matrix. In the present study, we used the patch-clamp technique in the outside-out configuration to record the activity of mitoBKCa channels. This allowed for the application of channel modulators to the intermembrane-space side of the mitoBKCa. We found that hemin applied in this configuration inhibits the activity of mitoBKCa. In addition, we proved that the observed hemin effect is specific and it is not due to its interaction with the inner mitochondrial membrane. Our data suggest the existence of a new potential heme/hemin binding site in the structure of the mitoBKCa channel located on the mitochondrial intermembrane space side, which could constitute a new way for the regulation of mitoBKCa channel activity.


Assuntos
Cálcio , Hemina , Hemina/farmacologia , Hemina/metabolismo , Cálcio/metabolismo , Mitocôndrias/metabolismo , Membranas Mitocondriais/metabolismo , Canais de Potássio Ativados por Cálcio de Condutância Alta/metabolismo
6.
Int J Mol Sci ; 23(22)2022 Nov 10.
Artigo em Inglês | MEDLINE | ID: mdl-36430359

RESUMO

Mitochondrial oxidative phospho rylation, the center of cellular metabolism, is pivotal for the energy production in eukaryotes. Mitochondrial oxidative phosphorylation relies on the mitochondrial respiratory chain, which consists of four main enzyme complexes and two mobile electron carriers. Mitochondrial enzyme complexes also assemble into respiratory chain supercomplexes (SCs) through specific interactions. The SCs not only have respiratory functions but also improve the efficiency of electron transfer and reduce the production of reactive oxygen species (ROS). Impaired assembly of SCs is closely related to various diseases, especially neurodegenerative diseases. Therefore, SCs play important roles in improving the efficiency of the mitochondrial respiratory chain, as well as maintaining the homeostasis of cellular metabolism. Here, we review the structure, assembly, and functions of SCs, as well as the relationship between mitochondrial SCs and diseases.


Assuntos
Mitocôndrias , Membranas Mitocondriais , Transporte de Elétrons , Membranas Mitocondriais/metabolismo , Mitocôndrias/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Fosforilação Oxidativa , Complexos Multienzimáticos/metabolismo
7.
Cell Death Dis ; 13(11): 966, 2022 Nov 17.
Artigo em Inglês | MEDLINE | ID: mdl-36396625

RESUMO

Mitophagy is an important metabolic mechanism that modulates mitochondrial quality and quantity by selectively removing damaged or unwanted mitochondria. BNIP3 (BCL2/adenovirus e1B 19 kDa protein interacting protein 3), a mitochondrial outer membrane protein, is a mitophagy receptor that mediates mitophagy under various stresses, particularly hypoxia, since BNIP3 is a hypoxia-responsive protein. However, the underlying mechanisms that regulate BNIP3 and thus mediate mitophagy under hypoxic conditions remain elusive. Here, we demonstrate that in hypoxia JNK1/2 (c-Jun N-terminal kinase 1/2) phosphorylates BNIP3 at Ser 60/Thr 66, which hampers proteasomal degradation of BNIP3 and drives mitophagy by facilitating the direct binding of BNIP3 to LC3 (microtubule-associated protein 1 light chain 3), while PP1/2A (protein phosphatase 1/2A) represses mitophagy by dephosphorylating BNIP3 and triggering its proteasomal degradation. These findings reveal the intrinsic mechanisms cells use to regulate mitophagy via the JNK1/2-BNIP3 pathway in response to hypoxia. Thus, the JNK1/2-BNIP3 signaling pathway strongly links mitophagy to hypoxia and may be a promising therapeutic target for hypoxia-related diseases.


Assuntos
Hipóxia , Mitofagia , Humanos , Hipóxia/metabolismo , Proteínas de Membrana/metabolismo , Mitocôndrias/metabolismo , Membranas Mitocondriais/metabolismo , Mitofagia/fisiologia , Fosforilação , Proteínas Proto-Oncogênicas/metabolismo , Proteína Quinase 8 Ativada por Mitógeno/metabolismo , Proteína Quinase 9 Ativada por Mitógeno/metabolismo
8.
Genes (Basel) ; 13(10)2022 10 18.
Artigo em Inglês | MEDLINE | ID: mdl-36292774

RESUMO

Cardiolipin (CL) is a unique, tetra-acylated diphosphatidylglycerol lipid that mainly localizes in the inner mitochondria membrane (IMM) in mammalian cells and plays a central role in regulating mitochondrial architecture and functioning. A deficiency of CL biosynthesis and remodeling perturbs mitochondrial functioning and ultrastructure. Clinical and experimental studies on human patients and animal models have also provided compelling evidence that an abnormal CL content, acyl chain composition, localization, and level of oxidation may be directly linked to multiple diseases, including cardiomyopathy, neuronal dysfunction, immune cell defects, and metabolic disorders. The central role of CL in regulating the pathogenesis and progression of these diseases has attracted increasing attention in recent years. In this review, we focus on the advances in our understanding of the physiological roles of CL biosynthesis and remodeling from human patients and mouse models, and we provide an overview of the potential mechanism by which CL regulates the mitochondrial architecture and functioning.


Assuntos
Cardiolipinas , Mitocôndrias , Animais , Camundongos , Humanos , Cardiolipinas/metabolismo , Mitocôndrias/metabolismo , Membranas Mitocondriais/metabolismo , Mamíferos
9.
Mol Cell ; 82(22): 4307-4323.e10, 2022 Nov 17.
Artigo em Inglês | MEDLINE | ID: mdl-36306796

RESUMO

Coenzyme Q (CoQ) is a redox-active lipid essential for core metabolic pathways and antioxidant defense. CoQ is synthesized upon the mitochondrial inner membrane by an ill-defined "complex Q" metabolon. Here, we present structure-function analyses of a lipid-, substrate-, and NADH-bound complex comprising two complex Q subunits: the hydroxylase COQ7 and the lipid-binding protein COQ9. We reveal that COQ7 adopts a ferritin-like fold with a hydrophobic channel whose substrate-binding capacity is enhanced by COQ9. Using molecular dynamics, we further show that two COQ7:COQ9 heterodimers form a curved tetramer that deforms the membrane, potentially opening a pathway for the CoQ intermediates to translocate from the bilayer to the proteins' lipid-binding sites. Two such tetramers assemble into a soluble octamer with a pseudo-bilayer of lipids captured within. Together, these observations indicate that COQ7 and COQ9 cooperate to access hydrophobic precursors within the membrane and coordinate subsequent synthesis steps toward producing CoQ.


Assuntos
Membranas Mitocondriais , Ubiquinona , Humanos , Ubiquinona/química , Membranas Mitocondriais/metabolismo , Proteínas de Transporte , Lipídeos
10.
J Cell Sci ; 135(22)2022 11 15.
Artigo em Inglês | MEDLINE | ID: mdl-36314270

RESUMO

The single mitochondrion of Toxoplasma gondii is highly dynamic, being predominantly in a peripherally distributed lasso-shape in intracellular parasites and collapsed in extracellular parasites. The peripheral positioning of the mitochondrion is associated with apparent contacts between the mitochondrion membrane and the parasite pellicle. The outer mitochondrial membrane-associated protein LMF1 is critical for the correct positioning of the mitochondrion. Intracellular parasites lacking LMF1 fail to form the lasso-shaped mitochondrion. To identify other proteins that tether the mitochondrion of the parasite to the pellicle, we performed a yeast two-hybrid screen for LMF1 interactors. We identified 70 putative interactors localized in different cellular compartments, such as the apical end of the parasite, mitochondrial membrane and the inner membrane complex (IMC), including with the pellicle protein IMC10. Using protein-protein interaction assays, we confirmed the interaction of LMF1 with IMC10. Conditional knockdown of IMC10 does not affect parasite viability but severely affects mitochondrial morphology in intracellular parasites and mitochondrial distribution to the daughter cells during division. In effect, IMC10 knockdown phenocopies disruption of LMF1, suggesting that these two proteins define a novel membrane tether between the mitochondrion and the IMC in Toxoplasma. This article has an associated First Person interview with the first author of the paper.


Assuntos
Parasitos , Toxoplasma , Animais , Proteínas de Membrana/metabolismo , Mitocôndrias/metabolismo , Membranas Mitocondriais/metabolismo , Parasitos/metabolismo , Proteínas de Protozoários/genética , Proteínas de Protozoários/metabolismo , Toxoplasma/metabolismo
11.
BMB Rep ; 55(11): 528-534, 2022 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-36195565

RESUMO

Mitochondria are cellular organelles that perform various functions within cells. They are responsible for ATP production, cell-signal regulation, autophagy, and cell apoptosis. Because the mitochondrial proteins that perform these functions need Ca2+ ions for their activity, mitochondria have ion channels to selectively uptake Ca2+ ions from the cytoplasm. The ion channel known to play the most important role in the Ca2+ uptake in mitochondria is the mitochondrial calcium uniporter (MCU) holo-complex located in the inner mitochondrial membrane (IMM). This ion channel complex exists in the form of a complex consisting of the pore-forming protein through which the Ca2+ ions are transported into the mitochondrial matrix, and the auxiliary protein involved in regulating the activity of the Ca2+ uptake by the MCU holo-complex. Studies of this MCU holocomplex have long been conducted, but we didn't know in detail how mitochondria uptake Ca2+ ions through this ion channel complex or how the activity of this ion channel complex is regulated. Recently, the protein structure of the MCU holo-complex was identified, enabling the mechanism of Ca2+ uptake and its regulation by the MCU holo-complex to be confirmed. In this review, I will introduce the mechanism of action of the MCU holo-complex at the molecular level based on the Cryo-EM structure of the MCU holo-complex to help understand how mitochondria uptake the necessary Ca2+ ions through the MCU holo-complex and how these Ca2+ uptake mechanisms are regulated. [BMB Reports 2022; 55(11): 528-534].


Assuntos
Canais de Cálcio , Mitocôndrias , Canais de Cálcio/metabolismo , Mitocôndrias/metabolismo , Membranas Mitocondriais/metabolismo , Cálcio/metabolismo
12.
Science ; 378(6617): 317-322, 2022 10 21.
Artigo em Inglês | MEDLINE | ID: mdl-36264797

RESUMO

In the mitochondrial outer membrane, α-helical transmembrane proteins play critical roles in cytoplasmic-mitochondrial communication. Using genome-wide CRISPR screens, we identified mitochondrial carrier homolog 2 (MTCH2), and its paralog MTCH1, and showed that it is required for insertion of biophysically diverse tail-anchored (TA), signal-anchored, and multipass proteins, but not outer membrane ß-barrel proteins. Purified MTCH2 was sufficient to mediate insertion into reconstituted proteoliposomes. Functional and mutational studies suggested that MTCH2 has evolved from a solute carrier transporter. MTCH2 uses membrane-embedded hydrophilic residues to function as a gatekeeper for the outer membrane, controlling mislocalization of TAs into the endoplasmic reticulum and modulating the sensitivity of leukemia cells to apoptosis. Our identification of MTCH2 as an insertase provides a mechanistic explanation for the diverse phenotypes and disease states associated with MTCH2 dysfunction.


Assuntos
Apoptose , Proteínas de Transporte da Membrana Mitocondrial , Membranas Mitocondriais , Proteínas de Transporte da Membrana Mitocondrial/química , Proteínas de Transporte da Membrana Mitocondrial/genética , Membranas Mitocondriais/metabolismo , Humanos , Retículo Endoplasmático/metabolismo , Células K562
13.
Prog Lipid Res ; 88: 101195, 2022 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-36202313

RESUMO

Cardiolipin (CL) is a unique phospholipid that is fundamental to the structure and function of the highly curved cristae membranes of mitochondria. Given its distinctive cone-shaped molecular architecture, CL induces negative membrane curvature in a bilayer setting. Another key feature of CL is its intrinsic ability to interact with various ligands, including cytochrome c, the anti-neoplastic anthracycline, doxorubicin, and the divalent cation, calcium. Although these, and other, binding interactions exert profound effects on mitochondrial and cellular function, they are difficult to study in intact mitochondria. Whereas liposomes provide a potential model membrane system, their relatively large size, limited ability to accommodate CL and the presence of an inaccessible interior bilayer leaflet, make these structures suboptimal. The discovery that CL can be formulated into aqueous soluble, reconstituted high density lipoprotein particles, termed nanodisks (ND), provides an alternative model membrane system. Comprised solely of CL and an apolipoprotein scaffold, CL-ND exist as a disk-shaped phospholipid bilayer whose perimeter is stabilized by contact with the scaffold protein. In these nanoscale particles, both leaflets of the bilayer are solvent accessible, an advantage for studies of ligand interactions. Recent experiments employing CL-ND have yielded novel insight into apoptosis, cardiotoxicity and CL-dependent bilayer to non-bilayer transitions.


Assuntos
Cardiolipinas , Membranas Mitocondriais , Cardiolipinas/química , Cardiolipinas/metabolismo , Membranas Mitocondriais/metabolismo , Mitocôndrias/metabolismo , Lipossomos , Doxorrubicina/metabolismo
14.
Cell Metab ; 34(11): 1792-1808.e6, 2022 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-36198313

RESUMO

The structural and functional organization of the mitochondrial respiratory chain (MRC) remains intensely debated. Here, we show the co-existence of two separate MRC organizations in human cells and postmitotic tissues, C-MRC and S-MRC, defined by the preferential expression of three COX7A subunit isoforms, COX7A1/2 and SCAFI (COX7A2L). COX7A isoforms promote the functional reorganization of distinct co-existing MRC structures to prevent metabolic exhaustion and MRC deficiency. Notably, prevalence of each MRC organization is reversibly regulated by the activation state of the pyruvate dehydrogenase complex (PDC). Under oxidative conditions, the C-MRC is bioenergetically more efficient, whereas the S-MRC preferentially maintains oxidative phosphorylation (OXPHOS) upon metabolic rewiring toward glycolysis. We show a link between the metabolic signatures converging at the PDC and the structural and functional organization of the MRC, challenging the widespread notion of the MRC as a single functional unit and concluding that its structural heterogeneity warrants optimal adaptation to metabolic function.


Assuntos
Glicólise , Fosforilação Oxidativa , Humanos , Transporte de Elétrons , Membranas Mitocondriais/metabolismo , Complexo Piruvato Desidrogenase/metabolismo , Isoformas de Proteínas/metabolismo
15.
Neural Plast ; 2022: 8057854, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36071748

RESUMO

Chronic pain is an enormous modern public health problem, with significant numbers of people debilitated by chronic pain from a variety of etiologies. Translocator protein 18 kDa (TSPO) was discovered in 1977 as a peripheral benzodiazepine receptor. It is a five transmembrane domain protein, mainly localized in the outer mitochondrial membrane. Recent and increasing studies have found changes in TSPO and its ligands in various chronic pain models. Reversing their expressions has been shown to alleviate chronic pain in these models, illustrating the effects of TSPO and its ligands. Herein, we review recent evidence and the mechanisms of TSPO in the development of chronic pain associated with peripheral nerve injury, spinal cord injury, cancer, and inflammatory responses. The cumulative evidence indicates that TSPO-based therapy may become an alternative strategy for treating chronic pain.


Assuntos
Dor Crônica , Receptores de GABA , Proteínas de Transporte/metabolismo , Dor Crônica/tratamento farmacológico , Dor Crônica/metabolismo , Humanos , Ligantes , Membranas Mitocondriais/metabolismo , Receptores de GABA/metabolismo
16.
Biochem J ; 479(17): 1857-1875, 2022 09 16.
Artigo em Inglês | MEDLINE | ID: mdl-36111979

RESUMO

Membrane contact sites (MCSs) mediate crucial physiological processes in eukaryotic cells, including ion signaling, lipid metabolism, and autophagy. Dysregulation of MCSs is closely related to various diseases, such as type 2 diabetes mellitus (T2DM), neurodegenerative diseases, and cancers. Visualization, proteomic mapping and manipulation of MCSs may help the dissection of the physiology and pathology MCSs. Recent technical advances have enabled better understanding of the dynamics and functions of MCSs. Here we present a summary of currently known functions of MCSs, with a focus on optical approaches to visualize and manipulate MCSs, as well as proteomic mapping within MCSs.


Assuntos
Diabetes Mellitus Tipo 2 , Retículo Endoplasmático , Diabetes Mellitus Tipo 2/metabolismo , Retículo Endoplasmático/metabolismo , Humanos , Membranas Mitocondriais/metabolismo , Optogenética , Proteômica
17.
Acta Neuropathol ; 144(5): 911-938, 2022 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-36104602

RESUMO

The mechanistic relationship between amyloid-beta precursor protein (APP) processing and mitochondrial dysfunction in Alzheimer's disease (AD) has long eluded the field. Here, we report that coiled-coil-helix-coiled-coil-helix domain containing 6 (CHCHD6), a core protein of the mammalian mitochondrial contact site and cristae organizing system, mechanistically connects these AD features through a circular feedback loop that lowers CHCHD6 and raises APP processing. In cellular and animal AD models and human AD brains, the APP intracellular domain fragment inhibits CHCHD6 transcription by binding its promoter. CHCHD6 and APP bind and stabilize one another. Reduced CHCHD6 enhances APP accumulation on mitochondria-associated ER membranes and accelerates APP processing, and induces mitochondrial dysfunction and neuronal cholesterol accumulation, promoting amyloid pathology. Compensation for CHCHD6 loss in an AD mouse model reduces AD-associated neuropathology and cognitive impairment. Thus, CHCHD6 connects APP processing and mitochondrial dysfunction in AD. This provides a potential new therapeutic target for patients.


Assuntos
Doença de Alzheimer , Amiloidose , Doença de Alzheimer/patologia , Amiloide/metabolismo , Peptídeos beta-Amiloides/metabolismo , Precursor de Proteína beta-Amiloide/genética , Precursor de Proteína beta-Amiloide/metabolismo , Amiloidose/metabolismo , Animais , Modelos Animais de Doenças , Humanos , Mamíferos/metabolismo , Camundongos , Camundongos Transgênicos , Mitocôndrias/metabolismo , Membranas Mitocondriais/metabolismo , Proteínas Mitocondriais
18.
Cells ; 11(18)2022 09 07.
Artigo em Inglês | MEDLINE | ID: mdl-36139365

RESUMO

The very large G protein-coupled receptor (VLGR1, ADGRV1) is the largest member of the adhesion GPCR family. Mutations in VLGR1 have been associated with the human Usher syndrome (USH), the most common form of inherited deaf-blindness as well as childhood absence epilepsy. VLGR1 was previously found as membrane-membrane adhesion complexes and focal adhesions. Affinity proteomics revealed that in the interactome of VLGR1, molecules are enriched that are associated with both the ER and mitochondria, as well as mitochondria-associated ER membranes (MAMs), a compartment at the contact sites of both organelles. We confirmed the interaction of VLGR1 with key proteins of MAMs by pull-down assays in vitro complemented by in situ proximity ligation assays in cells. Immunocytochemistry by light and electron microscopy demonstrated the localization of VLGR1 in MAMs. The absence of VLGR1 in tissues and cells derived from VLGR1-deficient mouse models resulted in alterations in the MAM architecture and in the dysregulation of the Ca2+ transient from ER to mitochondria. Our data demonstrate the molecular and functional interaction of VLGR1 with components in MAMs and point to an essential role of VLGR1 in the regulation of Ca2+ homeostasis, one of the key functions of MAMs.


Assuntos
Retículo Endoplasmático , Membranas Mitocondriais , Animais , Criança , Retículo Endoplasmático/metabolismo , Homeostase , Humanos , Camundongos , Mitocôndrias/metabolismo , Membranas Mitocondriais/metabolismo
19.
Cell Rep ; 40(12): 111364, 2022 09 20.
Artigo em Inglês | MEDLINE | ID: mdl-36130504

RESUMO

Mitochondria are dynamic organelles essential for cell survival whose structural and functional integrity rely on selective and regulated transport of lipids from/to the endoplasmic reticulum (ER) and across the mitochondrial intermembrane space. As they are not connected by vesicular transport, the exchange of lipids between ER and mitochondria occurs at membrane contact sites. However, the mechanisms and proteins involved in these processes are only beginning to emerge. Here, we show that the main physiological localization of the lipid transfer proteins ORP5 and ORP8 is at mitochondria-associated ER membrane (MAM) subdomains, physically linked to the mitochondrial intermembrane space bridging (MIB)/mitochondrial contact sites and cristae junction organizing system (MICOS) complexes that bridge the two mitochondrial membranes. We also show that ORP5/ORP8 mediate non-vesicular transport of phosphatidylserine (PS) lipids from the ER to mitochondria by cooperating with the MIB/MICOS complexes. Overall our study reveals a physical and functional link between ER-mitochondria contacts involved in lipid transfer and intra-mitochondrial membrane contacts maintained by the MIB/MICOS complexes.


Assuntos
Proteínas Mitocondriais , Fosfatidilserinas , Retículo Endoplasmático/metabolismo , Mitocôndrias/metabolismo , Membranas Mitocondriais/metabolismo , Proteínas Mitocondriais/metabolismo , Fosfatidilserinas/metabolismo
20.
Nat Commun ; 13(1): 5658, 2022 09 26.
Artigo em Inglês | MEDLINE | ID: mdl-36163196

RESUMO

ER-mitochondrial contact sites (EMCSs) are important for mitochondrial function. Here, we have identified a EMCS complex, comprising a family of uncharacterised mitochondrial outer membrane proteins, TRB1, TRB2, and the ER protein, VAP27-1. In Arabidopsis, there are three TraB family isoforms and the trb1/trb2 double mutant exhibits abnormal mitochondrial morphology, strong starch accumulation, and impaired energy metabolism, indicating that these proteins are essential for normal mitochondrial function. Moreover, TRB1 and TRB2 proteins also interact with ATG8 in order to regulate mitochondrial degradation (mitophagy). The turnover of depolarised mitochondria is significantly reduced in both trb1/trb2 and VAP27 mutants (vap27-1,3,4,6) under mitochondrial stress conditions, with an increased population of dysfunctional mitochondria present in the cytoplasm. Consequently, plant recovery after stress is significantly perturbed, suggesting that TRB1-regulated mitophagy and ER-mitochondrial interaction are two closely related processes. Taken together, we ascribe a dual role to TraB family proteins which are component of the EMCS complex in eukaryotes, regulating both interaction of the mitochondria to the ER and mitophagy.


Assuntos
Arabidopsis , Mitofagia , Arabidopsis/genética , Arabidopsis/metabolismo , Mitocôndrias/genética , Mitocôndrias/metabolismo , Membranas Mitocondriais/metabolismo , Proteínas Mitocondriais/metabolismo , Mitofagia/genética , Proteínas R-SNARE/metabolismo , Amido/metabolismo
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