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1.
Int J Mol Sci ; 25(9)2024 Apr 24.
Artigo em Inglês | MEDLINE | ID: mdl-38731864

RESUMO

The human brain possesses three predominate phospholipids, phosphatidylcholine (PC), phosphatidylethanolamine (PE) and phosphatidylserine (PS), which account for approximately 35-40%, 35-40%, and 20% of the brain's phospholipids, respectively. Mitochondrial membranes are relatively diverse, containing the aforementioned PC, PE, and PS, as well as phosphatidylinositol (PI) and phosphatidic acid (PA); however, cardiolipin (CL) and phosphatidylglycerol (PG) are exclusively present in mitochondrial membranes. These phospholipid interactions play an essential role in mitochondrial fusion and fission dynamics, leading to the maintenance of mitochondrial structural and signaling pathways. The essential nature of these phospholipids is demonstrated through the inability of mitochondria to tolerate alteration in these specific phospholipids, with changes leading to mitochondrial damage resulting in neural degeneration. This review will emphasize how the structure of phospholipids relates to their physiologic function, how their metabolism facilitates signaling, and the role of organ- and mitochondria-specific phospholipid compositions. Finally, we will discuss the effects of global ischemia and reperfusion on organ- and mitochondria-specific phospholipids alongside the novel therapeutics that may protect against injury.


Assuntos
Encéfalo , Parada Cardíaca , Mitocôndrias , Fosfolipídeos , Humanos , Fosfolipídeos/metabolismo , Mitocôndrias/metabolismo , Animais , Encéfalo/metabolismo , Encéfalo/patologia , Parada Cardíaca/metabolismo , Transdução de Sinais , Membranas Mitocondriais/metabolismo , Dinâmica Mitocondrial
2.
Int J Biol Sci ; 20(7): 2576-2591, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38725862

RESUMO

We showed that microtubule-associated tumor suppressor gene (MTUS1/ATIP) downregulation correlated with poor survival in head and neck squamous cell carcinoma (HNSCC) patients and that MTUS1/ATIP1 was the most abundant isoform in HNSCC tissue. However, the location and function of MTUS1/ATIP1 have remain unclear. In this study, we confirmed that MTUS1/ATIP1 inhibited proliferation, growth and metastasis in HNSCC in cell- and patient-derived xenograft models in vitro and in vivo. MTUS1/ATIP1 localized in the outer mitochondrial membrane, influence the morphology, movement and metabolism of mitochondria and stimulated oxidative stress in HNSCC cells by directly interacting with MFN2. MTUS1/ATIP1 activated ROS, recruiting Bax to mitochondria, facilitating cytochrome c release to the cytosol to activate caspase-3, and inducing GSDME-dependent pyroptotic death in HNSCC cells. Our findings showed that MTUS1/ATIP1 localized in the outer mitochondrial membrane in HNSCC cells and mediated anticancer effects through ROS-induced pyroptosis, which may provide a novel therapeutic strategy for HNSCC treatment.


Assuntos
Neoplasias de Cabeça e Pescoço , Mitocôndrias , Piroptose , Espécies Reativas de Oxigênio , Carcinoma de Células Escamosas de Cabeça e Pescoço , Humanos , Espécies Reativas de Oxigênio/metabolismo , Neoplasias de Cabeça e Pescoço/metabolismo , Neoplasias de Cabeça e Pescoço/patologia , Neoplasias de Cabeça e Pescoço/genética , Animais , Linhagem Celular Tumoral , Mitocôndrias/metabolismo , Carcinoma de Células Escamosas de Cabeça e Pescoço/metabolismo , Carcinoma de Células Escamosas de Cabeça e Pescoço/patologia , Carcinoma de Células Escamosas de Cabeça e Pescoço/genética , Camundongos , Proteínas Mitocondriais/metabolismo , Proteínas Mitocondriais/genética , Carcinoma de Células Escamosas/metabolismo , Carcinoma de Células Escamosas/patologia , Carcinoma de Células Escamosas/genética , Camundongos Nus , Proteínas Supressoras de Tumor/metabolismo , Proteínas Supressoras de Tumor/genética , Membranas Mitocondriais/metabolismo , Proliferação de Células
3.
PLoS Biol ; 22(4): e3002602, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38669296

RESUMO

Mitofusins are large GTPases that trigger fusion of mitochondrial outer membranes. Similarly to the human mitofusin Mfn2, which also tethers mitochondria to the endoplasmic reticulum (ER), the yeast mitofusin Fzo1 stimulates contacts between Peroxisomes and Mitochondria when overexpressed. Yet, the physiological significance and function of these "PerMit" contacts remain unknown. Here, we demonstrate that Fzo1 naturally localizes to peroxisomes and promotes PerMit contacts in physiological conditions. These contacts are regulated through co-modulation of Fzo1 levels by the ubiquitin-proteasome system (UPS) and by the desaturation status of fatty acids (FAs). Contacts decrease under low FA desaturation but reach a maximum during high FA desaturation. High-throughput genetic screening combined with high-resolution cellular imaging reveal that Fzo1-mediated PerMit contacts favor the transit of peroxisomal citrate into mitochondria. In turn, citrate enters the TCA cycle to stimulate the mitochondrial membrane potential and maintain efficient mitochondrial fusion upon high FA desaturation. These findings thus unravel a mechanism by which inter-organelle contacts safeguard mitochondrial fusion.


Assuntos
Mitocôndrias , Dinâmica Mitocondrial , Peroxissomos , Proteínas de Saccharomyces cerevisiae , Saccharomyces cerevisiae , Peroxissomos/metabolismo , Dinâmica Mitocondrial/fisiologia , Mitocôndrias/metabolismo , Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/metabolismo , Proteínas de Saccharomyces cerevisiae/genética , Ácidos Graxos/metabolismo , GTP Fosfo-Hidrolases/metabolismo , GTP Fosfo-Hidrolases/genética , Proteínas Mitocondriais/metabolismo , Proteínas Mitocondriais/genética , Retículo Endoplasmático/metabolismo , Proteínas de Membrana/metabolismo , Proteínas de Membrana/genética , Complexo de Endopeptidases do Proteassoma/metabolismo , Ciclo do Ácido Cítrico , Potencial da Membrana Mitocondrial/fisiologia , Membranas Mitocondriais/metabolismo , Humanos
4.
Proc Natl Acad Sci U S A ; 121(19): e2317703121, 2024 May 07.
Artigo em Inglês | MEDLINE | ID: mdl-38687792

RESUMO

Fluorescence labeling of chemically fixed specimens, especially immunolabeling, plays a vital role in super-resolution imaging as it offers a convenient way to visualize cellular structures like mitochondria or the distribution of biomolecules with high detail. Despite the development of various distinct probes that enable super-resolved stimulated emission depletion (STED) imaging of mitochondria in live cells, most of these membrane-potential-dependent fluorophores cannot be retained well in mitochondria after chemical fixation. This lack of suitable mitochondrial probes has limited STED imaging of mitochondria to live cell samples. In this study, we introduce a mitochondria-specific probe, PK Mito Orange FX (PKMO FX), which features a fixation-driven cross-linking motif and accumulates in the mitochondrial inner membrane. It exhibits high fluorescence retention after chemical fixation and efficient depletion at 775 nm, enabling nanoscopic imaging both before and after aldehyde fixation. We demonstrate the compatibility of this probe with conventional immunolabeling and other strategies commonly used for fluorescence labeling of fixed samples. Moreover, we show that PKMO FX facilitates correlative super-resolution light and electron microscopy, enabling the correlation of multicolor fluorescence images and transmission EM images via the characteristic mitochondrial pattern. Our probe further expands the mitochondrial toolkit for multimodal microscopy at nanometer resolutions.


Assuntos
Aldeídos , Corantes Fluorescentes , Microscopia de Fluorescência , Mitocôndrias , Mitocôndrias/metabolismo , Humanos , Corantes Fluorescentes/química , Aldeídos/metabolismo , Aldeídos/química , Microscopia de Fluorescência/métodos , Células HeLa , Reagentes de Ligações Cruzadas/química , Animais , Membranas Mitocondriais/metabolismo
5.
J Mol Biol ; 436(10): 168559, 2024 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-38580077

RESUMO

Upstream open reading frames (uORFs) are cis-acting elements that can dynamically regulate the translation of downstream ORFs by suppressing downstream translation under basal conditions and, in some cases, increasing downstream translation under stress conditions. Computational and empirical methods have identified uORFs in the 5'-UTRs of approximately half of all mouse and human transcripts, making uORFs one of the largest regulatory elements known. Because the prevailing dogma was that eukaryotic mRNAs produce a single functional protein, the peptides and small proteins, or microproteins, encoded by uORFs were rarely studied. We hypothesized that a uORF in the SLC35A4 mRNA is producing a functional microprotein (SLC35A4-MP) because of its conserved amino acid sequence. Through a series of biochemical and cellular experiments, we find that the 103-amino acid SLC35A4-MP is a single-pass transmembrane inner mitochondrial membrane (IMM) microprotein. The IMM contains the protein machinery crucial for cellular respiration and ATP generation, and loss of function studies with SLC35A4-MP significantly diminish maximal cellular respiration, indicating a vital role for this microprotein in cellular metabolism. The findings add SLC35A4-MP to the growing list of functional microproteins and, more generally, indicate that uORFs that encode conserved microproteins are an untapped reservoir of functional microproteins.


Assuntos
Membranas Mitocondriais , Fases de Leitura Aberta , Fases de Leitura Aberta/genética , Humanos , Membranas Mitocondriais/metabolismo , Animais , Camundongos , Proteínas Mitocondriais/metabolismo , Proteínas Mitocondriais/genética , Sequência de Aminoácidos , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Regiões 5' não Traduzidas/genética , Biossíntese de Proteínas , Mitocôndrias/metabolismo , Mitocôndrias/genética
6.
Biochem Soc Trans ; 52(2): 911-922, 2024 Apr 24.
Artigo em Inglês | MEDLINE | ID: mdl-38629718

RESUMO

To date, there is no general physical model of the mechanism by which unfolded polypeptide chains with different properties are imported into the mitochondria. At the molecular level, it is still unclear how transit polypeptides approach, are captured by the protein translocation machinery in the outer mitochondrial membrane, and how they subsequently cross the entropic barrier of a protein translocation pore to enter the intermembrane space. This deficiency has been due to the lack of detailed structural and dynamic information about the membrane pores. In this review, we focus on the recently determined sub-nanometer cryo-EM structures and our current knowledge of the dynamics of the mitochondrial two-pore outer membrane protein translocation machinery (TOM core complex), which provide a starting point for addressing the above questions. Of particular interest are recent discoveries showing that the TOM core complex can act as a mechanosensor, where the pores close as a result of interaction with membrane-proximal structures. We highlight unusual and new correlations between the structural elements of the TOM complexes and their dynamic behavior in the membrane environment.


Assuntos
Mitocôndrias , Membranas Mitocondriais , Mitocôndrias/metabolismo , Membranas Mitocondriais/metabolismo , Proteínas do Complexo de Importação de Proteína Precursora Mitocondrial , Transporte Proteico , Microscopia Crioeletrônica/métodos , Humanos , Proteínas de Transporte da Membrana Mitocondrial/metabolismo , Proteínas de Transporte da Membrana Mitocondrial/química , Modelos Moleculares , Conformação Proteica , Animais
7.
Mitochondrion ; 76: 101880, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38604459

RESUMO

Plasma membrane large-conductance calcium-activated potassium (BKCa) channels are important players in various physiological processes, including those mediated by epithelia. Like other cell types, human bronchial epithelial (HBE) cells also express BKCa in the inner mitochondrial membrane (mitoBKCa). The genetic relationships between these mitochondrial and plasma membrane channels and the precise role of mitoBKCa in epithelium physiology are still unclear. Here, we tested the hypothesis that the mitoBKCa channel is encoded by the same gene as the plasma membrane BKCa channel in HBE cells. We also examined the impact of channel loss on the basic function of HBE cells, which is to create a tight barrier. For this purpose, we used CRISPR/Cas9 technology in 16HBE14o- cells to disrupt the KCNMA1 gene, which encodes the α-subunit responsible for forming the pore of the plasma membrane BKCa channel. Electrophysiological experiments demonstrated that the disruption of the KCNMA1 gene resulted in the loss of BKCa-type channels in the plasma membrane and mitochondria. We have also shown that HBE ΔαBKCa cells exhibited a significant decrease in transepithelial electrical resistance which indicates a loss of tightness of the barrier created by these cells. We have also observed a decrease in mitochondrial respiration, which indicates a significant impairment of these organelles. In conclusion, our findings indicate that a single gene encodes both populations of the channel in HBE cells. Furthermore, this channel is critical for maintaining the proper function of epithelial cells as a cellular barrier.


Assuntos
Brônquios , Células Epiteliais , Subunidades alfa do Canal de Potássio Ativado por Cálcio de Condutância Alta , Humanos , Subunidades alfa do Canal de Potássio Ativado por Cálcio de Condutância Alta/metabolismo , Subunidades alfa do Canal de Potássio Ativado por Cálcio de Condutância Alta/genética , Brônquios/metabolismo , Brônquios/citologia , Células Epiteliais/metabolismo , Linhagem Celular , Mitocôndrias/metabolismo , Sistemas CRISPR-Cas , Mucosa Respiratória/metabolismo , Mucosa Respiratória/citologia , Membrana Celular/metabolismo , Membranas Mitocondriais/metabolismo , Membranas Mitocondriais/fisiologia
8.
Redox Biol ; 72: 103150, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38599016

RESUMO

Niemann-Pick type C (NPC) disease is a lysosomal storage disorder characterized by impaired motor coordination due to neurological defects and cerebellar dysfunction caused by the accumulation of cholesterol in endolysosomes. Besides the increase in lysosomal cholesterol, mitochondria are also enriched in cholesterol, which leads to decreased membrane fluidity, impaired mitochondrial function and loss of GSH, and has been shown to contribute to the progression of NPC disease. S-Adenosyl-l-methionine (SAM) regulates membrane physical properties through the generation of phosphatidylcholine (PC) from phosphatidylethanolamine (PE) methylation and functions as a GSH precursor by providing cysteine in the transsulfuration pathway. However, the role of SAM in NPC disease has not been investigated. Here we report that Npc1-/- mice exhibit decreased brain SAM levels but unchanged S-adenosyl-l-homocysteine content and lower expression of Mat2a. Brain mitochondria from Npc1-/- mice display decreased mitochondrial GSH levels and liquid chromatography-high resolution mass spectrometry analysis reveal a lower PC/PE ratio in mitochondria, contributing to increased mitochondrial membrane order. In vivo treatment of Npc1-/- mice with SAM restores SAM levels in mitochondria, resulting in increased PC/PE ratio, mitochondrial membrane fluidity and subsequent replenishment of mitochondrial GSH levels. In vivo SAM treatment improves the decline of locomotor activity, increases Purkinje cell survival in the cerebellum and extends the average and maximal life spam of Npc1-/- mice. These findings identify SAM as a potential therapeutic approach for the treatment of NPC disease.


Assuntos
Encéfalo , Glutationa , Fluidez de Membrana , Membranas Mitocondriais , Doença de Niemann-Pick Tipo C , S-Adenosilmetionina , Animais , Camundongos , S-Adenosilmetionina/metabolismo , Membranas Mitocondriais/metabolismo , Doença de Niemann-Pick Tipo C/metabolismo , Doença de Niemann-Pick Tipo C/tratamento farmacológico , Doença de Niemann-Pick Tipo C/genética , Glutationa/metabolismo , Encéfalo/metabolismo , Mitocôndrias/metabolismo , Proteína C1 de Niemann-Pick , Modelos Animais de Doenças , Camundongos Knockout , Fosfatidilcolinas/metabolismo
9.
J Cell Biol ; 223(6)2024 Jun 03.
Artigo em Inglês | MEDLINE | ID: mdl-38669038

RESUMO

Membrane contact sites (MCS) between mitochondria and the nucleus have been recently described. Termed nucleus associated mitochondria (NAM), they prime the expression of genes required for cellular resistance to stressors, thus offering a tethering mechanism for homeostatic communication. Here, we discuss the composition of NAM and their physiological and pathological significance.


Assuntos
Núcleo Celular , Mitocôndrias , Animais , Humanos , Núcleo Celular/metabolismo , Núcleo Celular/genética , Mitocôndrias/metabolismo , Mitocôndrias/genética , Membranas Mitocondriais/metabolismo , Células Eucarióticas/citologia
10.
Neurosci Lett ; 830: 137778, 2024 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-38621504

RESUMO

The endoplasmic reticulum (ER) plays an indispensable role in cellular processes, including maintenance of calcium homeostasis, and protein folding, synthesized and processing. Disruptions in these processes leading to ER stress and the accumulation of misfolded proteins can instigate the unfolded protein response (UPR), culminating in either restoration of balanced proteostasis or apoptosis. A key player in this intricate balance is CLCC1, an ER-resident chloride channel, whose essential role extends to retinal development, regulation of ER stress, and UPR. The importance of CLCC1 is further underscored by its interaction with proteins localized to mitochondria-associated endoplasmic reticulum membranes (MAMs), where it participates in UPR induction by MAM proteins. In previous research, we identified a p.(Asp25Glu) pathogenic CLCC1 variant associated with retinitis pigmentosa (RP) (CLCC1 hg38 NC_000001.11; NM_001048210.3, c.75C > A; UniprotKB Q96S66). In attempt to decipher the impact of this variant function, we leveraged liquid chromatography-mass spectrometry (LC-MS) to identify likely CLCC1-interacting proteins. We discovered that the CLCC1 interactome is substantially composed of proteins that localize to ER compartments and that the Asp25Glu variant results in noticeable loss and gain of specific protein interactors. Intriguingly, the analysis suggests that the CLCC1Asp25Glu mutant protein exhibits a propensity for increased interactions with cytoplasmic proteins compared to its wild-type counterpart. To corroborate our LC-MS data, we further scrutinized two novel CLCC1 interactors, Calnexin and SigmaR1, chaperone proteins that localize to the ER and MAMs. Through microscopy, we demonstrate that CLCC1 co-localizes with both proteins, thereby validating our initial findings. Moreover, our results reveal that CLCC1 co-localizes with SigmaR1 not merely at the ER, but also at MAMs. These findings reinforce the notion of CLCC1 interacting with MAM proteins at the ER-mitochondria interface, setting the stage for further exploration into how these interactions impact ER or mitochondria function and lead to retinal degenerative disease when impaired.


Assuntos
Retículo Endoplasmático , Receptores sigma , Receptor Sigma-1 , Humanos , Retículo Endoplasmático/metabolismo , Receptores sigma/metabolismo , Receptores sigma/genética , Resposta a Proteínas não Dobradas , Células HEK293 , Mitocôndrias/metabolismo , Mitocôndrias/genética , Membranas Mitocondriais/metabolismo , Retinose Pigmentar/metabolismo , Retinose Pigmentar/genética , Retinose Pigmentar/patologia
11.
Biochem Biophys Res Commun ; 709: 149836, 2024 May 21.
Artigo em Inglês | MEDLINE | ID: mdl-38564937

RESUMO

Mitochondria are essential cellular organelles; detecting mitochondrial damage is crucial in cellular biology and toxicology. Compared with existing chemical probe detection methods, genetically encoded fluorescent protein sensors can directly indicate cellular and molecular events without involving exogenous reagents. In this study, we introduced a molecular sensor system, MMD-Sensor, for monitoring mitochondrial membrane damage. The sensor consists of two molecular modules. Module I is a fusion structure of the mitochondrial localization sequence (MLS), AIF cleavage site sequence (CSS), nuclear localization sequence (NLS), N-terminus of mNeonGreen and mCherry. Module II is a fusion structure of the C-terminus of mNeonGreen, NLS sequence, and mtagBFP2. Under normal condition, Module I is constrained in the inner mitochondrial membrane anchored by MLS, while Module II is restricted to the nucleus by its NLS fusion component. If the mitochondrial membrane is damaged, CSS is cut from the inner membrane, causing Module I to shift into the nucleus guided by the NLS fusion component. After Module I enters the nucleus, the N- and C-terminus of mNeonGreen meet each other and rebuild its intact 3D structure through fragment complementation and thus generates green fluorescence in the nucleus. Dynamic migration of red fluorescence from mitochondria to the nucleus and generation of green fluorescence in the nucleus indicate mitochondrial membrane damage. Using the MMD-Sensor, mitochondrial membrane damage induced by various reagents, such as uncoupling agents, ATP synthase inhibitors, monovalent cationic carriers, and ROS, in HeLa and 293T cells are directly observed and evaluated.


Assuntos
Mitocôndrias , Membranas Mitocondriais , Humanos , Mitocôndrias/metabolismo , Membranas Mitocondriais/metabolismo , Proteínas de Fluorescência Verde/genética , Proteínas de Fluorescência Verde/metabolismo , Proteínas Luminescentes/genética , Proteínas Luminescentes/metabolismo , Células HeLa
12.
Cells ; 13(7)2024 Apr 07.
Artigo em Inglês | MEDLINE | ID: mdl-38607086

RESUMO

Miro GTPases are key components in the machinery responsible for transporting mitochondria and peroxisomes along microtubules, and also play important roles in regulating calcium homeostasis and organizing contact sites between mitochondria and the endoplasmic reticulum. Moreover, Miro GTPases have been shown to interact with proteins that actively regulate cytoskeletal organization and dynamics, suggesting that these GTPases participate in organizing cytoskeletal functions and organelle transport. Derailed mitochondrial transport is associated with neuropathological conditions such as Parkinson's and Alzheimer's diseases. This review explores our recent understanding of the diverse roles of Miro GTPases under cytoskeletal control, both under normal conditions and during the course of human diseases such as neuropathological disorders.


Assuntos
GTP Fosfo-Hidrolases , Mitocôndrias , Humanos , GTP Fosfo-Hidrolases/metabolismo , Mitocôndrias/metabolismo , Membranas Mitocondriais/metabolismo , Transporte Biológico , Microtúbulos/metabolismo
13.
EMBO Rep ; 25(4): 2071-2096, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38565738

RESUMO

Most mitochondrial proteins are synthesized on cytosolic ribosomes and imported into mitochondria in a post-translational reaction. Mitochondrial precursor proteins which use the ER-SURF pathway employ the surface of the endoplasmic reticulum (ER) as an important sorting platform. How they reach the mitochondrial import machinery from the ER is not known. Here we show that mitochondrial contact sites play a crucial role in the ER-to-mitochondria transfer of precursor proteins. The ER mitochondria encounter structure (ERMES) and Tom70, together with Djp1 and Lam6, are part of two parallel and partially redundant ER-to-mitochondria delivery routes. When ER-to-mitochondria transfer is prevented by loss of these two contact sites, many precursors of mitochondrial inner membrane proteins are left stranded on the ER membrane, resulting in mitochondrial dysfunction. Our observations support an active role of the ER in mitochondrial protein biogenesis.


Assuntos
Mitocôndrias , Proteínas de Saccharomyces cerevisiae , Mitocôndrias/metabolismo , Membranas Mitocondriais/metabolismo , Proteínas de Transporte da Membrana Mitocondrial/metabolismo , Transporte Proteico , Proteínas Mitocondriais/genética , Proteínas Mitocondriais/metabolismo , Retículo Endoplasmático/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo
14.
Biochemistry (Mosc) ; 89(2): 257-268, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-38622094

RESUMO

This paper presents new structural data about mitochondria using correlative light and electron microscopy (CLEM) and cryo-electron tomography. These state-of-the-art structural biology methods allow studying biological objects at nanometer scales under natural conditions. Non-invasiveness of these methods makes them comparable to observing animals in their natural environment on a safari. The paper highlights two areas of research that can only be accomplished using these methods. The study visualized location of the Aß42 amyloid aggregates in relation to mitochondria to test a hypothesis of development of mitochondrial dysfunction in Alzheimer's disease. The results showed that the Aß42 aggregates do not interact with mitochondria, although some of them are closely located. Therefore, the study demonstrated that mitochondrial dysfunction is not directly associated with the effects of aggregates on mitochondrial structure. Other processes should be considered as sources of mitochondrial dysfunction. Second unique area presented in this work is high-resolution visualization of the mitochondrial membranes and proteins in them. Analysis of the cryo-ET data reveals toroidal holes in the lamellar structures of cardiac mitochondrial cristae, where ATP synthases are located. The study proposes a new mechanism for sorting and clustering protein complexes in the membrane based on topology. According to this suggestion, position of the OXPHOS system proteins in the membrane is determined by its curvature. High-resolution tomography expands and complements existing ideas about the structural and functional organization of mitochondria. This makes it possible to study the previously inaccessible structural interactions of proteins with each other and with membranes in vivo.


Assuntos
Elétrons , Doenças Mitocondriais , Animais , Mitocôndrias/metabolismo , Membranas Mitocondriais/metabolismo , Microscopia Eletrônica , Doenças Mitocondriais/metabolismo
15.
Cells ; 13(7)2024 Mar 30.
Artigo em Inglês | MEDLINE | ID: mdl-38607048

RESUMO

Cardiolipin (CL) is a mitochondria-exclusive phospholipid synthesized in the inner mitochondrial membrane. CL plays a key role in mitochondrial membranes, impacting a plethora of functions this organelle performs. Consequently, it is conceivable that abnormalities in the CL content, composition, and level of oxidation may negatively impact mitochondrial function and dynamics, with important implications in a variety of diseases. This review concentrates on papers published in recent years, combined with basic and underexplored research in CL. We capture new findings on its biological functions in the mitochondria, as well as its association with neurodegenerative diseases such as Alzheimer's disease or Parkinson's disease. Lastly, we explore the potential applications of CL as a biomarker and pharmacological target to mitigate mitochondrial dysfunction.


Assuntos
Doenças Neurodegenerativas , Doença de Parkinson , Humanos , Cardiolipinas/metabolismo , Doenças Neurodegenerativas/metabolismo , Mitocôndrias , Membranas Mitocondriais/metabolismo , Doença de Parkinson/metabolismo
16.
Sci Rep ; 14(1): 8675, 2024 04 15.
Artigo em Inglês | MEDLINE | ID: mdl-38622160

RESUMO

Mitochondria are essential organelles in cellular energy metabolism and other cellular functions. Mitochondrial dysfunction is closely linked to cellular damage and can potentially contribute to the aging process. The purpose of this study was to investigate the subcellular structure of mitochondria and their activities in various cellular environments using super-resolution stimulated emission depletion (STED) nanoscopy. We examined the morphological dispersion of mitochondria below the diffraction limit in sub-cultured human primary skin fibroblasts and mouse skin tissues. Confocal microscopy provides only the overall morphology of the mitochondrial membrane and an indiscerptible location of nucleoids within the diffraction limit. Conversely, super-resolution STED nanoscopy allowed us to resolve the nanoscale distribution of translocase clusters on the mitochondrial outer membrane and accurately quantify the number of nucleoids per cell in each sample. Comparable results were obtained by analyzing the translocase distribution in the mouse tissues. Furthermore, we precisely and quantitatively analyzed biomolecular distribution in nucleoids, such as the mitochondrial transcription factor A (TFAM), using STED nanoscopy. Our findings highlight the efficacy of super-resolution fluorescence imaging in quantifying aging-related changes on the mitochondrial sub-structure in cells and tissues.


Assuntos
Mitocôndrias , Raios Ultravioleta , Humanos , Animais , Camundongos , Microscopia de Fluorescência/métodos , Mitocôndrias/metabolismo , Membranas Mitocondriais/metabolismo , Células HeLa
17.
FEMS Yeast Res ; 242024 Jan 09.
Artigo em Inglês | MEDLINE | ID: mdl-38587863

RESUMO

Previously, we reported an engineered Saccharomyces cerevisiae CEN.PK113-1A derivative able to produce succinic acid (SA) from glycerol with net CO2 fixation. Apart from an engineered glycerol utilization pathway that generates NADH, the strain was equipped with the NADH-dependent reductive branch of the TCA cycle (rTCA) and a heterologous SA exporter. However, the results indicated that a significant amount of carbon still entered the CO2-releasing oxidative TCA cycle. The current study aimed to tune down the flux through the oxidative TCA cycle by targeting the mitochondrial uptake of pyruvate and cytosolic intermediates of the rTCA pathway, as well as the succinate dehydrogenase complex. Thus, we tested the effects of deletions of MPC1, MPC3, OAC1, DIC1, SFC1, and SDH1 on SA production. The highest improvement was achieved by the combined deletion of MPC3 and SDH1. The respective strain produced up to 45.5 g/L of SA, reached a maximum SA yield of 0.66 gSA/gglycerol, and accumulated the lowest amounts of byproducts when cultivated in shake-flasks. Based on the obtained data, we consider a further reduction of mitochondrial import of pyruvate and rTCA intermediates highly attractive. Moreover, the approaches presented in the current study might also be valuable for improving SA production when sugars (instead of glycerol) are the source of carbon.


Assuntos
Saccharomyces cerevisiae , Ácido Succínico , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Ácido Succínico/metabolismo , Glicerol/metabolismo , Dióxido de Carbono/metabolismo , NAD/metabolismo , Ácido Pirúvico/metabolismo , Membranas Mitocondriais/metabolismo , Carbono/metabolismo , Engenharia Metabólica/métodos
18.
Cell Metab ; 36(5): 1059-1075.e9, 2024 May 07.
Artigo em Inglês | MEDLINE | ID: mdl-38458203

RESUMO

Mitochondrial cristae, infoldings of the mitochondrial inner membrane, undergo aberrant changes in their architecture with age. However, the underlying molecular mechanisms and their contribution to brain aging are largely elusive. Here, we observe an age-dependent accumulation of Glu-5'tsRNA-CTC, a transfer-RNA-derived small RNA (tsRNA), derived from nuclear-encoded tRNAGlu in the mitochondria of glutaminergic neurons. Mitochondrial Glu-5'tsRNA-CTC disrupts the binding of mt-tRNALeu and leucyl-tRNA synthetase2 (LaRs2), impairing mt-tRNALeu aminoacylation and mitochondria-encoded protein translation. Mitochondrial translation defects disrupt cristae organization, leading to damaged glutaminase (GLS)-dependent glutamate formation and reduced synaptosomal glutamate levels. Moreover, reduction of Glu-5'tsRNA-CTC protects aged brains from age-related defects in mitochondrial cristae organization, glutamate metabolism, synaptic structures, and memory. Thus, beyond illustrating a physiological role for normal mitochondrial cristae ultrastructure in maintaining glutamate levels, our study defines a pathological role for tsRNAs in brain aging and age-related memory decline.


Assuntos
Envelhecimento , Ácido Glutâmico , Camundongos Endogâmicos C57BL , Mitocôndrias , Biossíntese de Proteínas , Animais , Ácido Glutâmico/metabolismo , Envelhecimento/metabolismo , Mitocôndrias/metabolismo , Camundongos , Masculino , Humanos , Neurônios/metabolismo , Glutaminase/metabolismo , Glutaminase/genética , Membranas Mitocondriais/metabolismo , Encéfalo/metabolismo
19.
Mitochondrion ; 76: 101874, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38514017

RESUMO

Since the discovery of membrane contact sites between ER and mitochondria called mitochondria-associated membranes (MAMs), several pieces of evidence identified their role in the regulation of different cellular processes such as Ca2+ signalling, mitochondrial transport, and dynamics, ER stress, inflammation, glucose homeostasis, and autophagy. The integrity of these membranes was found to be essential for the maintenance of these cellular functions. Accumulating pieces of evidence suggest that MAMs serve as a platform for autophagosome formation. However, the alteration within MAMs structure is associated with the progression of neurodegenerative diseases. Dysregulated autophagy is a hallmark of neurodegeneration. Here, in this review, we highlight the present knowledge on MAMs, their structural composition, and their roles in different cellular functions. We also discuss the association of MAMs proteins with impaired autophagy and their involvement in the progression of neurodegenerative diseases such as Alzheimer's disease and Parkinson's disease.


Assuntos
Autofagia , Membranas Mitocondriais , Doenças Neurodegenerativas , Autofagia/fisiologia , Humanos , Doenças Neurodegenerativas/metabolismo , Doenças Neurodegenerativas/patologia , Membranas Mitocondriais/metabolismo , Mitocôndrias/metabolismo , Animais , Proteínas Mitocondriais/metabolismo , Proteínas de Membrana/metabolismo , Membranas Associadas à Mitocôndria
20.
RNA ; 30(6): 597-608, 2024 May 16.
Artigo em Inglês | MEDLINE | ID: mdl-38448244

RESUMO

The mammalian mitochondrial proteome comprises over 1000 proteins, with the majority translated from nuclear-encoded messenger RNAs (mRNAs). Mounting evidence suggests many of these mRNAs are localized to the outer mitochondrial membrane (OMM) in a pre- or cotranslational state. Upon reaching the mitochondrial surface, these mRNAs are locally translated to produce proteins that are cotranslationally imported into mitochondria. Here, we summarize various mechanisms cells use to localize RNAs, including transfer RNAs (tRNAs), to the OMM and recent technological advancements in the field to study these processes. While most early studies in the field were carried out in yeast, recent studies reveal RNA localization to the OMM and their regulation in higher organisms. Various factors regulate this localization process, including RNA sequence elements, RNA-binding proteins (RBPs), cytoskeletal motors, and translation machinery. In this review, we also highlight the role of RNA structures and modifications in mitochondrial RNA localization and discuss how these features can alter the binding properties of RNAs. Finally, in addition to RNAs related to mitochondrial function, RNAs involved in other cellular processes can also localize to the OMM, including those implicated in the innate immune response and piRNA biogenesis. As impairment of messenger RNA (mRNA) localization and regulation compromise mitochondrial function, future studies will undoubtedly expand our understanding of how RNAs localize to the OMM and investigate the consequences of their mislocalization in disorders, particularly neurodegenerative diseases, muscular dystrophies, and cancers.


Assuntos
Mitocôndrias , Membranas Mitocondriais , RNA Mitocondrial , Mitocôndrias/metabolismo , Mitocôndrias/genética , Humanos , Animais , Membranas Mitocondriais/metabolismo , RNA Mitocondrial/metabolismo , RNA Mitocondrial/genética , Proteínas de Ligação a RNA/metabolismo , Proteínas de Ligação a RNA/genética , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , RNA/metabolismo , RNA/genética , Transporte de RNA , RNA de Transferência/genética , RNA de Transferência/metabolismo , Biossíntese de Proteínas , Proteínas Mitocondriais/metabolismo , Proteínas Mitocondriais/genética
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