ABSTRACT
Pathological opening of the mitochondrial permeability transition pore (mPTP) is implicated in the pathogenesis of many disease processes such as myocardial ischemia, traumatic brain injury, Alzheimer's disease, and diabetes. While we have gained insight into mPTP biology over the last several decades, the lack of translation of this knowledge into successful clinical therapies underscores the need for continued investigation and use of different approaches to identify novel regulators of the mPTP with the hope of elucidating new therapeutic targets. Although the mPTP is known to be a voltage-gated channel, the identity of its voltage sensor remains unknown. Here we found decreased gating potential of the mPTP and increased expression and activity of sulfide quinone oxidoreductase (SQOR) in newborn Fragile X syndrome (FXS) mouse heart mitochondria, a model system of coenzyme Q excess and relatively decreased mPTP open probability. We further found that pharmacological inhibition and genetic silencing of SQOR increased mPTP open probability in vitro in adult murine cardiac mitochondria and in the isolated-perfused heart, likely by interfering with voltage sensing. Thus, SQOR is proposed to contribute to voltage sensing by the mPTP and may be a component of the voltage sensing apparatus that modulates the gating potential of the mPTP.
Subject(s)
Mitochondria, Heart , Mitochondrial Permeability Transition Pore , Oxidoreductases Acting on Sulfur Group Donors , Animals , Mice , Alzheimer Disease , Brain Injuries, Traumatic , Sulfides , Oxidoreductases Acting on Sulfur Group Donors/geneticsABSTRACT
Neuronal activity stimulates mRNA translation crucial for learning and development. While FMRP (Fragile X Mental Retardation Protein) and CYFIP1 (Cytoplasmic FMR1 Interacting Protein 1) regulate translation, the mechanism linking translation to neuronal activity is not understood. We now find that translation is stimulated when FMRP and CYFIP1 translocate to the potassium channel Slack (KCNT1, Slo2.2). When Slack is activated, both factors are released from eIF4E (Eukaryotic Initiation Factor 4E), where they normally inhibit translation initiation. A constitutively active Slack mutation and pharmacological stimulation of the wild-type channel both increase binding of FMRP and CYFIP1 to the channel, enhancing the translation of a reporter for ß-actin mRNA in cell lines and the synthesis of ß-actin in neuronal dendrites. Slack activity-dependent translation is abolished when both FMRP and CYFIP1 expression are suppressed. The effects of Slack mutations on activity-dependent translation may explain the severe intellectual disability produced by these mutations in humans. HIGHLIGHTS: Activation of Slack channels triggers translocation of the FMRP/CYFIP1 complexSlack channel activation regulates translation initiation of a ß-actin reporter constructA Slack gain-of-function mutation increases translation of ß-actin reporter construct and endogenous cortical ß-actinFMRP and CYFIP1 are required for Slack activity-dependent translation. IN BRIEF: Malone et al . show that the activation of Slack channels triggers translocation of the FMRP/CYFIP1 complex from the translation initiation factor eIF4E to the channel. This translocation releases eIF4E and stimulates mRNA translation of a reporter for ß-actin and cortical ß-actin mRNA, elucidating the mechanism that connects neuronal activity with translational regulation.
ABSTRACT
An instructive role for metabolism in embryonic patterning is emerging, although a role for mitochondria is poorly defined. We demonstrate that mitochondrial oxidative metabolism establishes the embryonic patterning center, the Spemann-Mangold Organizer, via hypoxia-inducible factor 1α (Hif-1α) in Xenopus. Hypoxia or decoupling ATP production from oxygen consumption expands the Organizer by activating Hif-1α. In addition, oxygen consumption is 20% higher in the Organizer than in the ventral mesoderm, indicating an elevation in mitochondrial respiration. To reconcile increased mitochondrial respiration with activation of Hif-1α, we discovered that the "free" c-subunit ring of the F1Fo ATP synthase creates an inner mitochondrial membrane leak, which decouples ATP production from respiration at the Organizer, driving Hif-1α activation there. Overexpression of either the c-subunit or Hif-1α is sufficient to induce Organizer cell fates even when ß-catenin is inhibited. We propose that mitochondrial leak metabolism could be a general mechanism for activating Hif-1α and Wnt signaling.
Subject(s)
Hypoxia-Inducible Factor 1, alpha Subunit , Mitochondria , Organizers, Embryonic , Animals , Adenosine Triphosphate/metabolism , Hypoxia , Mitochondria/metabolism , Organizers, Embryonic/metabolism , Xenopus laevisABSTRACT
The mitochondrial permeability transition (mPT) describes a Ca2+-dependent and cyclophilin D (CypD)-facilitated increase of inner mitochondrial membrane permeability that allows diffusion of molecules up to 1.5 kDa in size. It is mediated by a non-selective channel, the mitochondrial permeability transition pore (mPTP). Sustained mPTP opening causes mitochondrial swelling, which ruptures the outer mitochondrial membrane leading to subsequent apoptotic and necrotic cell death, and is implicated in a range of pathologies. However, transient mPTP opening at various sub-conductance states may contribute several physiological roles such as alterations in mitochondrial bioenergetics and rapid Ca2+ efflux. Since its discovery decades ago, intensive efforts have been made to identify the exact pore-forming structure of the mPT. Both the adenine nucleotide translocase (ANT) and, more recently, the mitochondrial F1FO (F)-ATP synthase dimers, monomers or c-subunit ring alone have been implicated. Here we share the insights of several key investigators with different perspectives who have pioneered mPT research. We critically assess proposed models for the molecular identity of the mPTP and the mechanisms underlying its opposing roles in the life and death of cells. We provide in-depth insights into current controversies, seeking to achieve a degree of consensus that will stimulate future innovative research into the nature and role of the mPTP.
Subject(s)
Mitochondrial Membrane Transport Proteins , Mitochondrial Permeability Transition Pore , Mitochondrial Permeability Transition Pore/analysis , Mitochondrial Permeability Transition Pore/metabolism , Mitochondrial Membrane Transport Proteins/metabolism , Consensus , Mitochondria/metabolism , Mitochondrial Membranes/metabolismABSTRACT
The presence of circulating cancer cells in the bloodstream is positively correlated with metastasis. We hypothesize that fluid shear stress (FSS) occurring during circulation alters mitochondrial function, enhancing metastatic behaviors of cancer cells. MCF7 and MDA-MB-231 human breast cancer cells subjected to FSS exponentially increased proliferation. Notably, FSS-treated cells consumed more oxygen but were resistant to uncoupler-mediated ATP loss. We found that exposure to FSS downregulated the F1FO ATP synthase c-subunit and overexpression of the c-subunit arrested cancer cell migration. Approaches that regulate c-subunit abundance may reduce the likelihood of breast cancer metastasis.
Subject(s)
Breast Neoplasms , Mitochondrial Proton-Translocating ATPases , Humans , Female , Mitochondrial Proton-Translocating ATPases/genetics , Mitochondrial Proton-Translocating ATPases/metabolism , Breast Neoplasms/genetics , Breast Neoplasms/pathology , Down-Regulation , Adenosine Triphosphate , Cell Proliferation , OxygenABSTRACT
Alpha-tocotrienol (α-TCT) is a member of the vitamin E family. It has been reported to protect the brain against various pathologies including cerebral ischemia and neurodegeneration. However, it is still unclear if α-TCT exhibits beneficial effects during brain development. We hypothesized that treatment with α-TCT improves intracellular redox homeostasis supporting normal development of neurons. We found that primary hippocampal neurons isolated from rat feti grown in α-TCT-containing media achieved greater levels of neurite complexity compared to ethanol-treated control neurons. Neurons were treated with 1 µM α-TCT for 3 weeks, and media were replaced with fresh α-TCT every week. Treatment with α-TCT increased α-TCT levels (26 pmol/mg protein) in the cells, whereas the control neurons did not contain α-TCT. α-TCT-treated neurons produced adenosine triphosphate (ATP) at a higher rate and increased ATP retention at neurites, supporting formation of neurite branches. Although treatment with α-TCT alone did not change neuronal viability, neurons grown in α-TCT were more resistant to death at maturity. We further found that messenger RNA and protein levels of B-cell lymphoma-extra large (Bcl-xL) are increased by α-TCT treatment without inducing posttranslational cleavage of Bcl-xL. Bcl-xL is known to enhance mitochondrial energy production, which improves neuronal function including neurite outgrowth and neurotransmission. Therefore α-TCT-mediated Bcl-xL upregulation may be the central mechanism of neuroprotection seen in the α-TCT-treated group. In summary, treatment with α-TCT upregulates Bcl-xL and increases ATP levels at neurites. This correlates with increased neurite branching during development and with protection of mature neurons against oxidative stress.
Subject(s)
Lymphoma, B-Cell , Neurons , Adenosine Triphosphate/metabolism , Adenosine Triphosphate/pharmacology , Animals , Hippocampus/metabolism , Lymphoma, B-Cell/metabolism , Rats , Tocotrienols , Up-Regulation , bcl-X Protein/genetics , bcl-X Protein/metabolismABSTRACT
Mitochondrial ATP synthase is vital not only for cellular energy production but also for energy dissipation and cell death. ATP synthase c-ring was suggested to house the leak channel of mitochondrial permeability transition (mPT), which activates during excitotoxic ischemic insult. In this present study, we purified human c-ring from both eukaryotic and prokaryotic hosts to biophysically characterize its channel activity. We show that purified c-ring forms a large multi-conductance, voltage-gated ion channel that is inhibited by the addition of ATP synthase F1 subcomplex. In contrast, dissociation of F1 from FO occurs during excitotoxic neuronal death suggesting that the F1 constitutes the gate of the channel. mPT is known to dissipate the osmotic gradient across the inner membrane during cell death. We show that ATP synthase c-subunit knock down (KD) prevents the osmotic change in response to high calcium and eliminates large conductance, Ca2+ and CsA sensitive channel activity of mPT. These findings elucidate the gating mechanism of the ATP synthase c-subunit leak channel (ACLC) and suggest how ACLC opening is regulated by cell stress in a CypD-dependent manner.
Subject(s)
Mitochondrial Membrane Transport Proteins , Mitochondrial Proton-Translocating ATPases , Adenosine Triphosphate/metabolism , Cell Death , Humans , Mitochondrial Membrane Transport Proteins/metabolism , Mitochondrial Permeability Transition Pore , Mitochondrial Proton-Translocating ATPases/genetics , Mitochondrial Proton-Translocating ATPases/metabolism , Proton-Translocating ATPases/metabolismABSTRACT
BACKGROUND: Long-term nitrofurantoin (NF) treatment can result in pulmonary and hepatic injury. Current guidelines do not outline the type or frequency of monitoring required for detection of these injuries. AIM: To assess 1) awareness of NF complications among prescribers; 2) monitoring practice; and 3) to describe the pulmonary sequelae of NF-related complications. DESIGN & SETTING: Evaluation of prescribing habits by questionnaires and review of GP databases, and case-note review in secondary care. METHOD: The following study procedures were undertaken: 1) an electronic questionnaire was distributed to prescribers, interrogating prescribing and monitoring practices, and awareness of complications; 2) an analysis was undertaken (June-July 2020) of NF monitoring among GPs in the local clinical commissioning group (CCG); and 3) a case review was carried out of patients diagnosed with NF-induced interstitial lung disease (NFILD) at the interstitial lung disease (ILD) centre (2014-2020). RESULTS: A total of 125 prescribers of long-term NF responded to the questionnaire (82.4% GPs; 12.0% urologists). Many were unaware of the potential for liver (42.4%) and lung (28.0%) complications; 40.8% and 52.8% never monitored for these, respectively. Only 53.3% of urologists believed themselves responsible for arranging monitoring, while nearly all GPs believed this to be the prescriber's responsibility (94.2%). One-third of all responders considered current British National Formulary (BNF) guidelines 'not at all sufficient/clear', with mean clarity scoring of 2.2/5. Among patients with NFILD (n = 46), NF had been prescribed most often (69.6%) for treatment of recurrent UTI and 58.6% (n = 27) were prescribed for >6 months. On withdrawal of the medication 61.4% displayed resolution (completely or minimal fibrosis), while 15.9% of patients had progressive lung fibrosis. CONCLUSION: NF can cause marked or irreversible lung complications and there is currently a shortfall in awareness and monitoring. Existing monitoring guidelines should be augmented.
ABSTRACT
Since their discovery decades ago, the primary physiological and pathological effects of potassium channels have been attributed to their ion conductance, which sets membrane potential and repolarizes action potentials. For example, Kv3 family channels regulate neurotransmitter release by repolarizing action potentials. Here we report a surprising but crucial function independent of potassium conductance: by organizing the F-actin cytoskeleton in mouse nerve terminals, the Kv3.3 protein facilitates slow endocytosis, rapid endocytosis, vesicle mobilization to the readily releasable pool, and recovery of synaptic depression during repetitive firing. A channel mutation that causes spinocerebellar ataxia inhibits endocytosis, vesicle mobilization, and synaptic transmission during repetitive firing by disrupting the ability of the channel to nucleate F-actin. These results unmask novel functions of potassium channels in endocytosis and vesicle mobilization crucial for sustaining synaptic transmission during repetitive firing. Potassium channel mutations that impair these "non-conducting" functions may thus contribute to generation of diverse neurological disorders.
Subject(s)
Endocytosis/physiology , Shaw Potassium Channels/metabolism , Synaptic Transmission/physiology , Synaptic Vesicles/metabolism , Actins/metabolism , Animals , CHO Cells , Cricetulus , Mice , Mutation , Presynaptic Terminals/metabolism , Shaw Potassium Channels/geneticsABSTRACT
Bcl-xL is a pro-survival protein of the Bcl2 family found in the mitochondrial membrane. Bcl-xL supports growth, development, and maturation of neurons, and it also prevents neuronal death during neurotoxic stimulation. This article reviews the mechanisms and upstream signaling that regulate the activity and abundance of Bcl-xL. Our team and others have reported that oxidative stress is a key regulator of intracellular Bcl-xL balance in neurons. Oxidative stress regulates synthesis, degradation, and activity of Bcl-xL and therefore neuronal function. During apoptosis, pro-apoptotic Bcl2 proteins such as Bax and Bak translocate to and oligomerize in the mitochondrial membrane. Formation of oligomers causes release of cytochrome c and activation of caspases that lead to neuronal death. Bcl-xL binds directly to pro-apoptotic Bcl2 proteins to block apoptotic signaling. Although anti-apoptotic roles of Bcl-xL have been well documented, an increasing number of studies in recent decades show that protein binding partners of Bcl-xL are not limited to Bcl2 proteins. Bcl-xL forms a complex with F1Fo ATP synthase, DJ-1, DRP1, IP3R, and the ryanodine receptor. These proteins support physiological processes in neurons such as growth and development and prevent neuronal damage by regulating mitochondrial ATP production, synapse formation, synaptic vesicle recycling, neurotransmission, and calcium signaling. However, under conditions of oxidative stress, Bcl-xL undergoes proteolytic cleavage thus lowering the abundance of functional Bcl-xL in neurons. Additionally, oxidative stress alters formation of Bcl-xL-mediated multiprotein complexes by regulating post-translational phosphorylation. Finally, oxidative stress regulates transcription factors that target the Bcl-x gene and alter accessibility of microRNA to mRNA influencing mRNA levels of Bcl-xL. In this review, we discussed how Bcl-xL supports the normal physiology of neurons, and how oxidative stress contributes to pathology by manipulating the dynamics of Bcl-xL production, degradation, and activity.
ABSTRACT
Loss of the gene (Fmr1) encoding Fragile X mental retardation protein (FMRP) causes increased mRNA translation and aberrant synaptic development. We find neurons of the Fmr1-/y mouse have a mitochondrial inner membrane leak contributing to a "leak metabolism." In human Fragile X syndrome (FXS) fibroblasts and in Fmr1-/y mouse neurons, closure of the ATP synthase leak channel by mild depletion of its c-subunit or pharmacological inhibition normalizes stimulus-induced and constitutive mRNA translation rate, decreases lactate and key glycolytic and tricarboxylic acid (TCA) cycle enzyme levels, and triggers synapse maturation. FMRP regulates leak closure in wild-type (WT), but not FX synapses, by stimulus-dependent ATP synthase ß subunit translation; this increases the ratio of ATP synthase enzyme to its c-subunit, enhancing ATP production efficiency and synaptic growth. In contrast, in FXS, inability to close developmental c-subunit leak prevents stimulus-dependent synaptic maturation. Therefore, ATP synthase c-subunit leak closure encourages development and attenuates autistic behaviors.
Subject(s)
Adenosine Triphosphate/metabolism , Fragile X Syndrome/metabolism , Protein Subunits/metabolism , Animals , Cell Line , Citric Acid Cycle/physiology , Fibroblasts/metabolism , Fragile X Mental Retardation Protein/metabolism , HEK293 Cells , Humans , Mice , Neurons/metabolism , RNA, Messenger , Synapses/metabolismABSTRACT
The mitochondrial F1Fo ATP synthase is one of the most abundant proteins of the mitochondrial inner membrane, which catalyzes the final step of oxidative phosphorylation to synthesize ATP from ADP and Pi. ATP synthase uses the electrochemical gradient of protons (ΔµH+) across the mitochondrial inner membrane to synthesize ATP. Under certain pathophysiological conditions, ATP synthase can run in reverse to hydrolyze ATP and build the necessary ΔµH+ across the mitochondrial inner membrane. Tight coupling between these two processes, proton translocation and ATP synthesis, is achieved by the unique rotational mechanism of ATP synthase and is necessary for efficient cellular metabolism and cell survival. The uncoupling of these processes, dissipation of mitochondrial inner membrane potential, elevated levels of ROS, low matrix content of ATP in combination with other cellular malfunction trigger the opening of the mitochondrial permeability transition pore in the mitochondrial inner membrane. In this review we will discuss the new role of ATP synthase beyond oxidative phosphorylation. We will highlight its function as a unique regulator of cell life and death and as a key target in mitochondria-mediated neurodegeneration and neuroprotection.
Subject(s)
Neurodegenerative Diseases/genetics , Neuroprotection/physiology , Proton-Translocating ATPases/physiology , Animals , Humans , Neurodegenerative Diseases/pathology , Proton-Translocating ATPases/geneticsABSTRACT
The mitochondrial permeability transition pore (mPTP) or mitochondrial megachannel is arguably one of the most mysterious phenomena in biology today. mPTP has been at the center of ongoing extensive scientific research for the last several decades. In this review we will discuss recent advances in the field that enhance our understanding of the molecular composition of mPTP, its regulatory mechanisms and its pathophysiological role. We will describe our recent findings on the role of ATP synthase c-subunit ring as a central player in mitochondrial permeability transition and as an important metabolic regulator during development and in degenerative diseases.
Subject(s)
Mitochondria , Mitochondrial Proton-Translocating ATPases , Protein Subunits , Animals , Humans , Disease Susceptibility , Energy Metabolism , Mitochondria/metabolism , Mitochondrial Membranes/chemistry , Mitochondrial Membranes/metabolism , Mitochondrial Proton-Translocating ATPases/chemistry , Mitochondrial Proton-Translocating ATPases/metabolism , Models, Molecular , Neuronal Plasticity , Neurons/metabolism , Permeability , Protein Conformation , Protein Subunits/chemistry , Protein Subunits/metabolismABSTRACT
Fragile X syndrome (FXS) is the leading known inherited intellectual disability and the most common genetic cause of autism. The full mutation results in transcriptional silencing of the Fmr1 gene and loss of fragile X mental retardation protein (FMRP) expression. Defects in neuroenergetic capacity are known to cause a variety of neurodevelopmental disorders. Thus, we explored the integrity of forebrain mitochondria in Fmr1 knockout mice during the peak of synaptogenesis. We found inefficient thermogenic respiration due to futile proton leak in Fmr1 KO mitochondria caused by coenzyme Q (CoQ) deficiency and an open cyclosporine-sensitive channel. Repletion of mitochondrial CoQ within the Fmr1 KO forebrain closed the channel, blocked the pathological proton leak, restored rates of protein synthesis during synaptogenesis, and normalized the key phenotypic features later in life. The findings demonstrate that FMRP deficiency results in inefficient oxidative phosphorylation during the neurodevelopment and suggest that dysfunctional mitochondria may contribute to the FXS phenotype.
Subject(s)
Cell Respiration/physiology , Fragile X Syndrome/metabolism , Fragile X Syndrome/pathology , Mitochondria/metabolism , Mitochondria/pathology , Thermogenesis/physiology , Animals , Autistic Disorder/metabolism , Autistic Disorder/pathology , Disease Models, Animal , Female , Fragile X Mental Retardation Protein/metabolism , Intellectual Disability/metabolism , Intellectual Disability/pathology , Male , Mice , Mice, Knockout , Neurogenesis/physiology , ProtonsABSTRACT
Purified mitochondrial ATP synthase has been shown to form Ca2+-activated, large conductance channel activity similar to that of mitochondrial megachannel (MMC) or mitochondrial permeability transition pore (mPTP) but the oligomeric state required for channel formation is being debated. We reconstitute purified monomeric ATP synthase from porcine heart mitochondria into small unilamellar vesicles (SUVs) with the lipid composition of mitochondrial inner membrane and analyze its oligomeric state by electron cryomicroscopy. The cryo-EM density map reveals the presence of a single ATP synthase monomer with no density seen for a second molecule tilted at an 86o angle relative to the first. We show that this preparation of SUV-reconstituted ATP synthase monomers, when fused into giant unilamellar vesicles (GUVs), forms voltage-gated and Ca2+-activated channels with the key features of mPTP. Based on our findings we conclude that the ATP synthase monomer is sufficient, and dimer formation is not required, for mPTP activity.
Subject(s)
Mitochondrial Proton-Translocating ATPases/metabolism , Mitochondrial Proton-Translocating ATPases/ultrastructure , Protein Subunits/metabolism , Animals , Calcium/metabolism , Cryoelectron Microscopy , Mitochondria, Heart/metabolism , Mitochondria, Heart/ultrastructure , Mitochondrial Membranes/metabolism , Mitochondrial Membranes/ultrastructure , Mitochondrial Proton-Translocating ATPases/isolation & purification , Protein Subunits/isolation & purification , Swine , Unilamellar Liposomes/isolation & purification , Unilamellar Liposomes/metabolismABSTRACT
Familial Parkinson's disease (PD) protein DJ-1 mutations are linked to early onset PD. We have found that DJ-1 binds directly to the F1FO ATP synthase ß subunit. DJ-1's interaction with the ß subunit decreased mitochondrial uncoupling and enhanced ATP production efficiency while in contrast mutations in DJ-1 or DJ-1 knockout increased mitochondrial uncoupling, and depolarized neuronal mitochondria. In mesencephalic DJ-1 KO cultures, there was a progressive loss of neuronal process extension. This was ameliorated by a pharmacological reagent, dexpramipexole, that binds to ATP synthase, closing a mitochondrial inner membrane leak and enhancing ATP synthase efficiency. ATP synthase c-subunit can form an uncoupling channel; we measured, therefore, ATP synthase F1 (ß subunit) and c-subunit protein levels. We found that ATP synthase ß subunit protein level in the DJ-1 KO neurons was approximately half that found in their wild-type counterparts, comprising a severe defect in ATP synthase stoichiometry and unmasking c-subunit. We suggest that DJ-1 enhances dopaminergic cell metabolism and growth by its regulation of ATP synthase protein components.
Subject(s)
Dopaminergic Neurons/metabolism , Mitochondria/metabolism , Mitochondrial Proton-Translocating ATPases/metabolism , Protein Deglycase DJ-1/metabolism , Animals , Gene Expression , Humans , Membrane Potential, Mitochondrial/genetics , Mice , Mice, Inbred C57BL , Mice, Knockout , Mitochondria/genetics , Mitochondrial Membranes/metabolism , Mitochondrial Proton-Translocating ATPases/genetics , Protein Binding , Protein Deglycase DJ-1/genetics , Rats, Sprague-DawleyABSTRACT
Mitochondrial metabolic plasticity is a key adaptive mechanism in response to changes in cellular metabolic demand. Changes in mitochondrial metabolic efficiency have been linked to pathophysiological conditions, including cancer, neurodegeneration, and obesity. The ubiquitously expressed DJ-1 (Parkinsonism-associated deglycase) is known as a Parkinson's disease gene and an oncogene. The pleiotropic functions of DJ-1 include reactive oxygen species scavenging, RNA binding, chaperone activity, endocytosis, and modulation of major signaling pathways involved in cell survival and metabolism. Nevertheless, how these functions are linked to the role of DJ-1 in mitochondrial plasticity is not fully understood. In this study, we describe an interaction between DJ-1 and 14-3-3ß that regulates the localization of DJ-1, in a hypoxia-dependent manner, either to the cytosol or to mitochondria. This interaction acts as a modulator of mitochondrial metabolic efficiency and a switch between glycolysis and oxidative phosphorylation. Modulation of this novel molecular mechanism of mitochondrial metabolic efficiency is potentially involved in the neuroprotective function of DJ-1 as well as its role in proliferation of cancer cells.-Weinert, M., Millet, A., Jonas, E. A., Alavian, K. N. The mitochondrial metabolic function of DJ-1 is modulated by 14-3-3ß.
Subject(s)
14-3-3 Proteins/metabolism , Mitochondria/metabolism , Protein Deglycase DJ-1/metabolism , Animals , Brain/metabolism , Female , Glycolysis , HEK293 Cells , Humans , Oxidative Phosphorylation , Protein Binding , Protein Transport , Rats , Rats, Sprague-DawleyABSTRACT
Permeability transition (PT) is an increase in mitochondrial inner membrane permeability that can lead to a disruption of mitochondrial function and cell death. PT is responsible for tissue damage in stroke and myocardial infarction. It is caused by the opening of a large conductance (â¼1.5 nS) channel, the mitochondrial PT pore (mPTP). We directly tested the role of the c-subunit of ATP synthase in mPTP formation by measuring channel activity in c-subunit knockout mitochondria. We found that the classic mPTP conductance was lacking in c-subunit knockout mitochondria, but channels sensitive to the PT inhibitor cyclosporine A could be recorded. These channels had a significantly lower conductance compared with the cyclosporine A-sensitive channels detected in parental cells and were sensitive to the ATP/ADP translocase inhibitor bongkrekic acid. We propose that, in the absence of the c-subunit, mPTP cannot be formed, and a distinct cyclosporine A-sensitive low-conductance channel emerges.