Impaired Mitochondrial Dynamics Research Articles

High-fat diet-induced mitochondrial dysfunction is associated with loss of protection from ischemic preconditioning in renal ischemia reperfusion.

Consumption of high-fat diet (HFD) promotes mitochondrial dysfunction and the latter act as a critical factor in determining the severity of ischemia-reperfusion (IR) injury in different cell types. Ischemic preconditioning (IPC), a well-known protocol that render IR protection in kidney works via mitochondria. In the present study, we evaluated how HFD kidney with underlying mitochondrial changes respond to precondition protocol after IR induction. Wistar male rats were used in this study and were divided into two groups: SD (standard diet; n = 18) and HFD (high-fat diet; n = 18), which were further subdivided into sham, ischemia-reperfusion, and precondition groups at the end of the dietary regimen. Blood biochemistry, renal injury marker, creatinine clearance (CrCl), mitochondrial quality (fission, fusion, and phagy), mitochondrial function via ETC enzyme activities and respiration, and signalling pathway were analysed. Sixteen weeks of HFD administration to the rat deteriorated the renal mitochondrial health measured via 10% decline in mitochondrial respiration index ADP/O (in GM), reduced mitochondrial copy number (55%), biogenesis (56%), low bioenergetics potential (19% complex I + III and 15% complex II + III), increased oxidative stress, and reduced expression of mitochondrial fusion genes compared with SD rats. IR procedure in HFD rat kidney inflicted significant mitochondrial dysfunction and further deteriorated copy number along with impaired mitophagy and mitochondrial dynamics. IPC could effectively ameliorate the renal ischemia injury in normal rat but failed to provide similar kind of protection in HFD rat kidney. Even though the IR-associated mitochondrial dysfunction in both normal and HFD rats were similar, the magnitude of overall dysfunction and corresponding renal injury and compromised physiology was high in HFD rats. This observation was further confirmed via in vitro protein translation assay in isolated mitochondria from normal and HFD rat kidney that showed significantly reduction in the response ability of mitochondria in HFD. In conclusion, the deteriorated mitochondrial function and its quality along with low mitochondrial copy number and downregulation of mitochondrial dynamic gene exhibited by HFD rat kidney augments the sensitivity of renal tissue towards the IR injury which leads to the compromised protective ability by ischemic preconditioning.

Chronic exposure to polluted urban air aggravates myocardial infarction by impaired cardiac mitochondrial function and dynamics

Chronic exposure to polluted urban air aggravates myocardial infarction by impaired cardiac mitochondrial function and dynamics

P7C3-A20 Attenuates Microglial Inflammation and Brain Injury after ICH through Activating the NAD+/Sirt3 Pathway.

Intracerebral hemorrhage (ICH) is lethal but lacks effective therapies. Nicotinamide adenine dinucleotide (NAD+) is a central metabolite indispensable for a broader range of fundamental intracellular biological functions. Reduction of NAD+ usually occurs after acute brain insults, and supplementation of NAD+ has been proven neuroprotective. P7C3-A20 is a novel compound featuring its ability to facilitate the flux of NAD+. In this study, we sought to determine the potential therapeutic value of P7C3-A20 in ICH. In collagenase-induced ICH mouse models, we found that P7C3-A20 treatment could diminish lesion volume, reduce blood-brain barrier (BBB) damage, mitigate brain edema, attenuate neural apoptosis, and improve neurological outcomes after ICH. Further, RNA sequencing and subsequent experiments revealed that ICH-induced neuroinflammation and microglial proinflammatory activities were significantly suppressed following P7C3-A20 treatment. Mitochondrial damage is an important trigger of inflammatory response. We examined mitochondrial morphology and function and found that P7C3-A20 could attenuate OxyHb-induced impairment of mitochondrial dynamics and functions in vitro. Mechanistically, Sirt3, an NAD+-dependent deacetylase located in mitochondria, was then found to play a vital role in the protection of P7C3-A20 against mitochondrial damage and inflammatory response. In rescue experiments, P7C3-A20 failed to exert those protective effects in microglia-specific Sirt3 conditional knockout (CKO) mice. Finally, preclinical research revealed a correlation between the plasma NAD+ level and the neurological outcome in ICH patients. These results demonstrate that P7C3-A20 is a promising therapeutic agent for neuroinflammatory injury after ICH and exerts protective actions, at least partly, in a Sirt3-dependent manner.

Zinc deficiency compromises the maturational competence of porcine oocyte by inducing mitophagy and apoptosis

Zinc, an essential trace mineral, plays a pivotal role in cell proliferation, maintenance of redox homeostasis, apoptosis, and aging. Serum zinc concentrations are reduced in patients with polycystic ovary syndrome (PCOS). However, the underlying mechanism of the effects of zinc deficiency on the female reproductive system, especially oocyte quality, has not been fully elucidated. Thus, we established an in vitro experimental model by adding N,N,N′,N′-Tetrakis(2-pyridylmethyl) ethylenediamine (TPEN) into the culture medium, and to determine the potential regulatory function of zinc during porcine oocytes maturation. In the present study, we found that zinc deficiency caused aberrant meiotic progress, accompanied by the disrupted cytoskeleton structure in porcine oocytes. Zinc deficiency impaired mitochondrial function and dynamics, leading to the increase of reactive oxygen species (ROS) and acetylation level of the antioxidative enzyme superoxide dismutase 2 (SOD2), eventually induced the occurrence of oxidative stress and early apoptosis. Moreover, zinc deficiency perturbed cytosolic Ca2+ homeostasis, lipid droplets formation, demonstrating the aberrant mitochondrial function in porcine oocytes. Importantly, we found that zinc deficiency in porcine oocytes induced the occurrence of mitophagy by activating the PTEN-induced kinase 1/Parkin signaling pathway. Collectively, our findings demonstrated that zinc was a critical trace mineral for maintaining oocyte quality by regulating mitochondrial function and autophagy in porcine oocytes.

Melatonin and metformin ameliorated trastuzumab-induced cardiotoxicity through the modulation of mitochondrial function and dynamics without reducing its anticancer efficacy

Trastuzumab has an impressive level of efficacy as regards antineoplasticity, however it can cause serious cardiotoxic side effects manifested by impaired cardiac contractile function. Although several pharmacological interventions, including melatonin and metformin, have been reported to protect against various cardiovascular diseases, their potential roles in trastuzumab-induced cardiotoxicity remain elusive. We hypothesized that either melatonin or metformin co-treatment effectively attenuates trastuzumab-mediated cardiotoxicity through attenuating the impaired mitochondrial function and mitochondrial dynamics. Male Wistar rats were divided into control (normal saline, n = 8) and trastuzumab group (4 mg/kg/day for 7 days, n = 24). Rats in the trastuzumab group were subdivided into 3 interventional groups (n = 8/group), and normal saline, or melatonin (10 mg/kg/day), or metformin (250 mg/kg/day) were orally administered for 7 consecutive days. Cardiac parameters were determined, and biochemical investigations were carried out on blood and heart tissues. Trastuzumab induced left ventricular (LV) dysfunction by increasing oxidative stress, inflammation, and apoptosis. It also impaired cardiac mitochondrial function, dynamics, and autophagy. Treatment with either melatonin or metformin equally attenuated trastuzumab-induced cardiac injury, indicated by a marked reduction in inflammation, oxidative damage, cardiac mitochondrial injury, mitochondrial dynamic imbalance, autophagy dysregulation, and apoptosis, leading to improved LV function, as demonstrated by increased LV ejection fraction. Melatonin and metformin conferred equal levels of cardioprotection against trastuzumab-induced cardiotoxicity, which may provide novel and promising approaches for management of cardiotoxicity induced by trastuzumab.

A case of NASH with genetic predisposition successfully treated with an SGLT2 inhibitor: a possible involvement of mitochondrial dysfunction.

In this study, we herein describe a 47-year-old Japanese woman who manifested inheritable non-alcoholic steatohepatitis (NASH) and severe dyslipidemia. Interestingly, her NASH progression was ameliorated by treatment with a sodium-glucose co-transporter 2 (SGLT2) inhibitor. This inheritability prompted us to comprehensively decode her genomic information using whole-exome sequencing. We found the well-established I148M mutation in PNPLA3 as well as mutations in LGALS3 and PEMT for her NASH. Mutations in GCKR may contribute to both NASH and dyslipidemia. We further mined gene mutations potentially responsible for her manifestations that led to the identification of a novel M188fs mutation in MUL1 that may be causally associated with her mitochondrial dysfunction. Our case may provide some clues to better understand this spectrum of disease as well as the rationale for selecting medications. While the PNPLA3 I148M mutation is well-established, accumulation of other mutations may accelerate susceptibility to non-alcoholic steatohepatitis (NASH). NASH and dyslipidemia may be intertwined biochemically and genetically through several key genes. SGLT2 inhibitors emerge as promising treatment for NASH albeit with interindividual variation in efficacy. Genetic background may explain the mechanisms behind the variation. A novel dysfunctional mutation in MUL1 may lead to metabolic inflexibilities through impaired mitochondrial dynamics and function.

Heme and Iron Aggravate Tissue Damage in Sickle Cell Disease By Driving Macrophage Functional Reprogramming through the Coordinated Suppression of Efferocytosis and Mitochondrial Metabolism

Introduction: Sickle cell disease (SCD) is hallmarked by an underlying chronic inflammatory status, which is in part driven by pro-inflammatory macrophages. Macrophages are highly plastic immune cells which integrate and respond to a variety of signals they are exposed to in the surrounding microenvironment. One of these stimuli is represented by heme released upon hemolysis, which acts as damage-associated molecular pattern to stimulate macrophage inflammatory phenotypic switching through TLR4 signaling and ROS production (Vinchi et al., Blood 2016). Heme-induced pro-inflammatory activation program in macrophages promotes sterile inflammation and aggravates hepatic fibrosis in SCD, contributing to the inflammatory landscape and organ damage typically associated with this disease. While previous studies addressed heme ability to induce inflammatory cytokine production in macrophages, how heme alters cell functional properties remains unexplored. Macrophage functions such as immune cell recruitment ability and apoptotic cell clearance are relevant in the context of SCD, where tissue damage and cell apoptosis occur frequently due to vaso-occlusive episodes, hypoxia and ischemic injury. Methods: Here we analyzed macrophage response to apoptotic stimuli in vivo, in mouse models of heme overload and SCD, as well as in vitro, in bone-marrow-derived macrophages (BMDMs), to unveil the impact of hemolysis on macrophage functional properties. Results: Our results demonstrate that, in addition to inflammatory activation, heme severely alters macrophage functional response to apoptotic cell damage by exacerbating their immune cell recruitment ability and impairing their efferocytic capacity. We show that exposure to heme excess drives defective efferocytosis of apoptotic neutrophils in BMDMs and mouse model of heme overload. This is fully recapitulated in SCD mice, where limited efferocytosis contributes to impaired apoptotic cell clearance and exacerbated tissue damage. Mechanistically, altered efferocytosis depends on heme-driven activation of TLR4 signaling pathway and the suppression of the nuclear transcription factor PPARγ and its coactivator PGC1α, which lead to reduced expression of efferocytic receptors and impaired mitochondrial dynamics and functions. This results in limited recognition/engulfment of apoptotic cells and decreased shift to aerobic mitochondrial fatty acid β-oxidation and anti-inflammatory IL-4 and IL-10 release, with consequent inhibition of continual efferocytosis, inflammation resolution and tissue repair. Heme-driven changes are associated with cell metabolic skewing towards glycolysis and pentose phosphate pathway and reduced reliance on mitochondrial fatty acid oxidation and TCA cycle. Macrophages pre-loaded with fatty acids showed decreased oxygen consumption rate and ATP production after heme exposure, indicating that heme-altered mitochondrial dynamics impair lipid catabolism via limited mitochondrial oxidative phosphorylation. Overall, heme induces macrophage phenotypic and functional reprogramming through the coordinated suppression of efferocytosis, via efferocytosis receptor downregulation, and fatty acid β-oxidation, via altered mitochondrial dynamics. We further demonstrate that heme-impaired efferocytosis and tissue damage promote autoimmunity through anti-nuclear antibody production against 'self' secondary necrotic cells, potentially explaining the increasing evidence of autoimmune diseases in SCD patients. Finally, hemopexin-mediated heme scavenging and anti-inflammatory IL-4 treatment improve tissue damage in hemolytic mice through macrophage rewiring. Defective efferocytosis is reproduced in vitro by macrophage exposure to SCD patients' plasma and rescued by heme scavenging via haptoglobin/hemopexin and PPARγ/PGC1α modulation via PPARα agonist or IL-4. Conclusion: Our data indicate that the therapeutic improvement of heme-altered macrophage functional properties via heme scavenging or PPARγ/PGC1α modulation significantly promotes the resolution of inflammation and ameliorates tissue damage associated with SCD pathophysiology. Thus, macrophage functional rewiring offers potentially valuable therapeutic strategies for SCD patients to improve tissue damage resolution upon vaso-occlusive crisis and ischemic events and prevent autoimmune conditions.

Xuanfei Baidu formula alleviates impaired mitochondrial dynamics and activated NLRP3 inflammasome by repressing NF-κB and MAPK pathways in LPS-induced ALI and inflammation models

BackgroundXuanfei Baidu Formula (XBF) is an effective traditional Chinese medicine (TCM) remedy for treating coronavirus disease 2019 (COVID-19) in China. This herbal medicine has shown effects in reducing clinical symptoms and shortening the average length of hospital stay for COVID-19 patients. Previous studies have demonstrated that XBF alleviates acute lung injury (ALI) by regulating macrophage-mediated immune inflammation, but the mechanisms of action remain elusive. PurposeThis study aimed to evaluate the lung-protective and anti-inflammatory effects of XBF and its underlying mechanisms. MethodsHere, XBF's effects were investigated in an ALI mouse model induced by inhalation of atomized lipopolysaccharide (LPS). Besides, the LPS-induced inflammation model in RAW264.7 cells was used to clarify the underlying mechanisms of XBF against ALI. ResultsOur results showed that XBF treatment alleviated LPS-induced lung injury, as evidenced by reduced histopathological changes, pulmonary alveoli permeability, fibrosis, and apoptosis in the lung tissues. In addition, inflammation was alleviated as shown by decreased levels of tumor necrosis factor (TNF)-α, interleukin (IL)-6, IL-1β in serum and bronchoalveolar lavage fluid (BALF), and reduced white blood cell (WBC) count in BALF. Furthermore, consistent with the in vivo assay, XBF inhibited LPS-induced inflammatory cytokines release and pro-inflammatory polarization in RAW264.7 cells. Mechanistically, XBF increased mitochondrial fusion by upregulating Mfn1 and attenuated NLRP3 inflammasome activation by repressing Casp11, respectively, to inhibit NF-κB and MAPK pathways, thus repressing pro-inflammatory macrophage polarization. ConclusionIn this study, we demonstrate that XBF exerts anti-ALI and -inflammatory effects by recovering mitochondrial dynamics and reducing inflammasome activation, providing a biological illustration of the clinical efficacy of XBF in treating COVID-19 patients.

Dynamin-like Protein 1 (DNML1) as a Molecular Target for Antibody-Based Immunotherapy to Treat Glaucoma.

Slow and progressive loss of retinal ganglion cells (RGCs) is the main characteristic of glaucoma, the second leading cause of blindness worldwide. Previous studies have shown that impaired mitochondrial dynamics could facilitate retinal neurodegeneration. Mitochondrial dynamics are regulated directly (fission) or more indirectly (fusion) by dynamin-like protein 1 (DNML1). Therefore, DNM1L might be a promising target for an antibody-based approach to treat glaucoma. The consequences of targeting endogenous DNM1L by antibodies in a glaucoma animal model have not been investigated yet. Here, we show that the intravitreal application of an anti-DNM1L antibody showed protective effects regarding the survival of RGCs and their axons in the retinal nerve fiber layer (RNFL). Antibody treatment also improved retinal functionality, as observed by electroretinography (Ganzfeld ERG). Western blot analysis revealed altered DNM1L phosphorylation and altered expression of proteins related to apoptosis suggesting a decreased apoptosis rate. Mass spectrometry analysis revealed 28 up-regulated and 21 down-regulated proteins (p < 0.05) in both experimental groups. Protein pathway analysis showed that many proteins interacted directly with the target protein DNM1L and could be classified into three main protein clusters: Vesicle traffic-associated (NSF, SNCA, ARF1), mitochondrion-associated (HSP9A, SLC25A5/ANT2, GLUD1) and cytoskeleton-associated (MAP1A) signaling pathway. Our results demonstrate that DNM1L is a promising target for an antibody-based approach to glaucoma therapy.

Impaired autophagy and mitochondrial dynamics are involved in Sorafenib-induced cardiomyocyte apoptosis

Sorafenib (Sor), a novel multi-target anticancer drug also induces severe toxicity in heart, while the mechanism of its cardiotoxicity remains to be fully elucidated. Dysregulation of autophagy and mitochondrial dynamics imbalance have been implicated in cardiomyocyte death. The aim of this study is to test the hypothesis that Sor disrupts autophagy and mitochondrial dynamics, thereby aggravating Sor-induced oxidative stress damage to cardiomyocytes. Our results revealed that Sor (≥ 5 μM) concentration- and time-dependently reduced cell viability and induced apoptosis in H9c2 myoblasts. Sor treatment promoted intracellular reactive oxygen species (ROS) generation, and subsequent Ca2+ overload as well as apoptosis, which were abolished by the ROS scavenger MPG. Sor inhibited the basal autophagy activity of cells, as supported by the fact that ERK1/2 inhibition-dependent decreases of autophagosomes and autolysosomes, and p62 accumulation in a concentration- and time-dependent manner. Improving autophagy with rapamycin abrogated Sor-induced ROS and Ca2+ overloads, and cell apoptosis. Furthermore, Sor compromised mitochondrial morphology and caused excessive mitochondrial fragmentation in cells. The imbalance of mitochondrial dynamics was attributed to ROS-mediated CaMKII overactivity, and increased phosphorylation of dynamin-related protein 1 (phosph-Drp1). Suppression of CaMKII with KN-93 or mitochondrial fission with mitochondrial division inhibitor-1 (Mdivi-1) attenuated Sor-induced ROS and Ca2+ overloads as well as apoptosis. In conclusion, these results provide the first evidence that impairments in autophagy and mitochondrial dynamics are involved in Sor-induced cardiomyocyte apoptosis. The present study may provide a potential strategy for preventing or reducing cardiotoxicity of Sor.

Impacts of impaired mitochondrial dynamics in hearing loss: Potential therapeutic targets.

Mitochondria are the powerhouse of the cells. Under physiological conditions, mitochondrial fission and fusion maintain a dynamic equilibrium in the cytoplasm, which is referred to as mitochondrial dynamics. As an important approach to regulating mitochondrial function and quantity, the role of mitochondrial dynamics has been demonstrated in the pathogenesis of various disease models, including brain damage, neurodegeneration, and stress. As the vital organ of the peripheral auditory system, the cochlea consumes a significant amount of energy, and the maintenance of mitochondrial homeostasis is essential for the cochlear auditory capacity. OPA1 functions as both a necessary gene regulating mitochondrial fusion and a pathogenic gene responsible for auditory neuropathy, suggesting that an imbalance in mitochondrial dynamics may play a critical role in hearing loss, but relevant studies are few. In this review, we summarize recent evidence regarding the role of mitochondrial dynamics in the pathogenesis of noise-induced hearing loss (NIHL), drug-induced hearing loss, hereditary hearing loss, and age-related hearing loss. The impacts of impaired mitochondrial dynamics on hearing loss are discussed, and the potential of mitochondrial dynamics for the prevention and treatment of hearing loss is considered.

A new K+channel-independent mechanism is involved in the antioxidant effect of XE-991 in an in vitro model of glucose metabolism impairment: implications for Alzheimer’s disease

Alzheimer’s disease (AD) is a neurodegenerative disorder that represents the first cause of dementia. Although there has been significant progress in AD research, the actual mechanisms underlying this pathology remain largely unknown. There is increasing evidence that oxidative stress, metabolic alterations, and mitochondrial dysfunction are key players in the development and worsening of AD. As a result, in the past few years, remarkable attempts have been made to develop neuroprotective strategies against the impairment of mitochondrial dynamics and cell redox status. In the present study, we reveal a novel antioxidant K+ channel-independent effect of the M-current inhibitor XE-991 in SH-SY5Y cells differentiated with retinoic acid (RA) and primary rat cortical neurons exposed to the glycolysis inhibitor glyceraldehyde (GA). This experimental approach aimed to create a condition of hypometabolism accompanied by mitochondrial dysfunction and redox imbalance, as frequently observed in the beginning stage of the disease. We found that XE-991 exerted a neuroprotective action most likely through the resumption of superoxide dismutase (SOD) activity, which was significantly compromised during GA challenge. We also observed that the enhancement of SOD activity was accompanied by a sequence of positive effects; these included the reduction in basal Ca2+ levels within cytoplasmic and mitochondrial compartments, the decrease in mitochondrial reactive oxygen species (ROS) production, the modulation of AMPK/mTOR pathway, the recovery of ΔΨm collapse, the increase in the intracellular ATP content and the decrease in amyloid-β (Aβ) and hyperphosphorylated form of tau protein (pTau) levels. Collectively, our study reveals an off-target antioxidant effect of XE-991 and paves the way toward the further evaluation of new therapeutic uses of already existing molecules to accelerate the process of developing an effective therapy to counteract AD.

Mitochondrial oxidative stress contributes to diastolic dysfunction through impaired mitochondrial dynamics

Diastolic dysfunction (DD) underlies heart failure with preserved ejection fraction (HFpEF), a clinical syndrome associated with aging that is becoming more prevalent. Despite extensive clinical studies, no effective treatment exists for HFpEF. Recent findings suggest that oxidative stress contributes to the pathophysiology of DD, but molecular mechanisms underpinning redox-sensitive cardiac remodeling in DD remain obscure. Using transgenic mice with mitochondria-targeted NOX4 overexpression (Nox4TG618) as a model, we demonstrate that NOX4-dependent mitochondrial oxidative stress induces DD in mice as measured by increased E/E′, isovolumic relaxation time, Tau Glantz and reduced dP/dtmin while EF is preserved. In Nox4TG618 mice, fragmentation of cardiomyocyte mitochondria, increased DRP1 phosphorylation, decreased expression of MFN2, and a higher percentage of apoptotic cells in the myocardium are associated with lower ATP-driven and maximal mitochondrial oxygen consumption rates, a decrease in respiratory reserve, and a decrease in citrate synthase and Complex I activities. Transgenic mice have an increased concentration of TGFβ and osteopontin in LV lysates, as well as MCP-1 in plasma, which correlates with a higher percentage of LV myocardial periostin- and ACTA2-positive cells compared with wild-type mice. Accordingly, the levels of ECM as measured by Picrosirius Red staining as well as interstitial deposition of collagen I are elevated in the myocardium of Nox4TG618 mice. The LV tissue of Nox4TG618 mice also exhibited increased ICaL current, calpain 2 expression, and altered/disrupted Z-disc structure. As it pertains to human pathology, similar changes were found in samples of LV from patients with DD. Finally, treatment with GKT137831, a specific NOX1 and NOX4 inhibitor, or overexpression of mCAT attenuated myocardial fibrosis and prevented DD in the Nox4TG618 mice.Together, our results indicate that mitochondrial oxidative stress contributes to DD by causing mitochondrial dysfunction, impaired mitochondrial dynamics, increased synthesis of pro-inflammatory and pro-fibrotic cytokines, activation of fibroblasts, and the accumulation of extracellular matrix, which leads to interstitial fibrosis and passive stiffness of the myocardium.Further, mitochondrial oxidative stress increases cardiomyocyte Ca2+ influx, which worsens CM relaxation and raises the LV filling pressure in conjunction with structural proteolytic damage.

The mitochondrial protein OPA1 regulates the quiescent state of adult muscle stem cells.

Quiescence regulation is essential for adult stem cell maintenance and sustained regeneration. Our studies uncovered that physiological changes in mitochondrial shape regulate the quiescent state of adult muscle stem cells (MuSCs). We show that MuSC mitochondria rapidly fragment upon an activation stimulus, via systemic HGF/mTOR, to drive the exit from deep quiescence. Deletion of the mitochondrial fusion protein OPA1 and mitochondrial fragmentation transitions MuSCs into G-alert quiescence, causing premature activation and depletion upon a stimulus. OPA1 loss activates a glutathione (GSH)-redox signaling pathway promoting cell-cycle progression, myogenic gene expression, and commitment. MuSCs with chronic OPA1 loss, leading to mitochondrial dysfunction, continue to reside in G-alert but acquire severe cell-cycle defects. Additionally, we provide evidence that OPA1 decline and impaired mitochondrial dynamics contribute to age-related MuSC dysfunction. These findings reveal a fundamental role for OPA1 and mitochondrial dynamics in establishing the quiescent state and activation potential of adult stem cells.

WWOX inhibition by Zfra1-31 restores mitochondrial homeostasis and viability of neuronal cells exposed to high glucose.

Diabetes has been associated with an increased risk of cognitive decline and dementia. However, the mechanisms underlying this association remain unclear and no effective therapeutic interventions exist. Accumulating evidence demonstrates that mitochondrial defects are a key feature of diabetes contributing to neurodegenerative events. It has also been demonstrated that the putative tumor suppressor WW domain-containing oxidoreductase 1 (WWOX) can interact with mitochondria in several pathological conditions. However, its role in diabetes-associated neurodegeneration remains unknown. So, this study aimed to evaluate the role of WWOX activation in high glucose-induced neuronal damage and death. Our experiments were mainly performed in differentiated SH-SY5Y neuroblastoma cells exposed to high glucose and treated (or not) with Zfra1-31, the specific inhibitor of WWOX. Several parameters were analyzed namely cell viability, WWOX activation (tyrosine 33 residue phosphorylation), mitochondrial function, reactive oxygen species (ROS) production, biogenesis, and dynamics, autophagy and oxidative stress/damage. The levels of the neurotoxic proteins amyloid β (Aβ) and phosphorylated Tau (pTau) and of synaptic integrity markers were also evaluated. We observed that high glucose increased the levels of activated WWOX. Interestingly, brain cortical and hippocampal homogenates from young (6-month old) diabetic GK rats showed increased levels of activated WWOX compared to older GK rats (12-month old) suggesting that WWOX plays an early role in the diabetic brain. In neuronal cells, high glucose impaired mitochondrial respiration, dynamics and biogenesis, increased mitochondrial ROS production and decreased mitochondrial membrane potential and ATP production. More, high glucose augmented oxidative stress/damage and the levels of Aβ and pTau proteins and affected autophagy, contributing to the loss of synaptic integrity and cell death. Of note, the activation of WWOX preceded mitochondrial dysfunction and cell death. Importantly, the inhibition of WWOX with Zfra1-31 reversed, totally or partially, the alterations promoted by high glucose. Altogether our observations demonstrate that under high glucose conditions WWOX activation contributes to mitochondrial anomalies and neuronal damage and death, which suggests that WWOX is a potential therapeutic target for early interventions. Our findings also support the efficacy of Zfra1-31 in treating hyperglycemia/diabetes-associated neurodegeneration.

Reduced VDAC1, Maintained Mitochondrial Dynamics and Enhanced Mitochondrial Biogenesis in a Transgenic Tau Mouse Model of Alzheimer's Disease.

Alzheimer’s disease (AD) is one of the most common forms of neurodegeneration, defined by reduced cognitive function, which is caused by the gradual death of neurons in the brain. Recent studies have shown an age-dependent rise in the levels of voltage-dependent anion channel 1 (VDAC1) in AD. In addition, we discovered an aberrant interaction between VDAC1 and P-TAU in the brains of AD patients, which led to abnormalities in the structural and functional integrity of the mitochondria. The purpose of our study is to understand the protective effects of reduced VDAC1 against impaired mitochondrial dynamics and defective mitochondrial biogenesis in transgenic TAU mice. Recently, we crossed heterozygote VDAC1 knockout (VDAC1+/−) mice with transgenic TAU mice to obtain double-mutant VDAC1+/−/TAU mice. Our goal was to evaluate whether a partial decrease in VDAC1 lessens the amount of mitochondrial toxicity in transgenic Tau (P301L) mice. We found that mitochondrial fission proteins were significantly reduced, and mitochondrial fusion and biogenesis proteins were increased in double-mutant mice compared to TAU mice. On the basis of these discoveries, the current work may have significance for the development of reduced-VDAC1-based treatments for individuals suffering from AD as well as other tauopathies.

Mitochondria Targeted Antioxidant Significantly Alleviates Preeclampsia Caused by 11β-HSD2 Dysfunction via OPA1 and MtDNA Maintenance.

We have previously demonstrated that placental 11β-hydroxysteroid dehydrogenase type 2 (11β-HSD2) dysfunction contributes to PE pathogenesis. We sought to elucidate molecular mechanisms underlying 11β-HSD2 dysfunction-induced PE and to seek potential therapeutic targets using a 11β-HSD2 dysfunction-induced PE-like rat model as well as cultured extravillous trophoblasts (EVTs) since PE begins with impaired function of EVTs. In 11β-HSD2 dysfunction-induced PE-like rat model, we revealed that placental mitochondrial dysfunction occurred, which was associated with mitDNA instability and impaired mitochondrial dynamics, such as decreased optic atrophy 1 (OPA1) expression. MitoTEMPO treatment significantly alleviated the hallmark of PE-like features and improved mitDNA stability and mitochondrial dynamics in the placentas of rat PE-like model. In cultured human EVTs, we found that 11β-HSD2 dysfunction led to mitochondrial dysfunction and disrupted mtDNA stability. MitoTEMPO treatment improved impaired invasion and migration induced by 11β-HSD2 dysfunction in cultured EVTs. Further, we revealed that OPA1 was one of the key factors that mediated 11β-HSD2 dysfunction-induced excess ROS production, mitochondrial dysfunction and mtDNA reduction. Our data indicates that 11β-HSD2 dysfunction causes mitochondrial dysfunctions, which impairs trophoblast function and subsequently results in PE development. Our study immediately highlights that excess ROS is a potential therapeutic target for PE.

Dietary Alterations in Impaired Mitochondrial Dynamics Due to Neurodegeneration.

Alzheimer’s disease is still an incurable disease with significant social and economic impact globally. Nevertheless, newly FDA-approved drugs and non-pharmacological techniques may offer efficient disease treatments. Furthermore, it is widely accepted that early diagnosis or even prognosis of Alzheimer’s disease using advanced computational tools could offer a compelling alternative way of management. In addition, several studies have presented an insight into the role of mitochondrial dynamics in Alzheimer’s development. In combination with diverse dietary and obesity-related diseases, mitochondrial bioenergetics may be linked to neurodegeneration. Considering the probabilistic expectations of Alzheimer’s disease development or progression due to specific risk factors or biomarkers, we designed a Bayesian model to formulate the impact of diet-induced obesity with an impaired mitochondrial function and altered behavior. The applied probabilities are based on clinical trials globally and are continuously subject to updating and redefinition. The proposed multiparametric model combines various data types based on uniform probabilities. The program simulates all the variables with a uniform distribution in a sample of 1000 patients. First, the program initializes the variable age (30–95) and the four different diet types (“HFO_diet,” “Starvation,” “HL_diet,” “CR”) along with the factors that are related to prodromal or mixed AD (ATP, MFN1, MFN2, DRP1, FIS1, Diabetes, Oxidative_Stress, Hypertension, Obesity, Depression, and Physical_activity). Besides the known proteins related to mitochondrial dynamics, our model includes risk factors like Age, Hypertension, Oxidative Stress, Obesity, Depression, and Physical Activity, which are associated with Prodromal Alzheimer’s. The outcome is the disease progression probability corresponding to a random individual ID related to diet choices and mitochondrial dynamics parameters. The proposed model and the programming code are adjustable to different parameters and values. The program is coded and executed in Python and is fully and freely available for research purposes and testing the correlation between diet type and Alzheimer’s disease progression regarding various risk factors and biomarkers.

Functional and dynamic mitochondrial damage by chloromethylisothiazolinone/methylisothiazolinone (CMIT/MIT) mixture in brain endothelial cell lines and rat cerebrovascular endothelium

The mixture of 5-chloro-2-methyl-4-isothiazolin-3-one (CMIT, chloromethylisothiazolinone) and 2-methyl-4-isothiazolin-3-one (MIT, methylisothiazolinone) is a commonly used biocide in consumer products. Despite the health issues related to its usage in cosmetics and humidifier disinfectants (HD), understanding its adverse outcome is still limited. Using in vitro cell lines and ex vivo rat models, we examined the effects of CMIT/MIT on the cellular redox homeostasis and energy metabolism in the brain microvascular endothelium, a highly restrictive interface between the bloodstream and brain. In murine bEND.3 and human hCMEC/D3, CMIT/MIT significantly amplified the mitochondrial-derived oxidative stress causing disruption of the mitochondrial membrane potential and oxidative phosphorylation at a sub-lethal concentration (1 μg/mL) or treatment duration (1 h). In addition, CMIT/MIT significantly increased a dynamic imbalance between mitochondrial fission and fusion, and endogenous pathological stressors significantly potentiated the CMIT/MIT-induced endothelial dysfunction. Notably, in the brain endothelium isolated from intravenously CMIT/MIT-administered rats, we observed significant mitochondrial damage and decreased tight junction protein. Taken together, we report that CMIT/MIT significantly impaired mitochondrial function and dynamics resulting in endothelial barrier dysfunction, giving an insight into the role of mitochondrial damage in CMIT/MIT-associated systemic health effects.

HAX1-dependent control of mitochondrial proteostasis governs neutrophil granulocyte differentiation.

The relevance of molecular mechanisms governing mitochondrial proteostasis to the differentiation and function of hematopoietic and immune cells is largely elusive. Through dissection of the network of proteins related to HCLS1-associated protein X-1, we defined a potentially novel functional CLPB/HAX1/(PRKD2)/HSP27 axis with critical importance for the differentiation of neutrophil granulocytes and, thus, elucidated molecular and metabolic mechanisms underlying congenital neutropenia in patients with HAX1 deficiency as well as bi- and monoallelic mutations in CLPB. As shown by stable isotope labeling by amino acids in cell culture (SILAC) proteomics, CLPB and HAX1 control the balance of mitochondrial protein synthesis and persistence crucial for proper mitochondrial function. Impaired mitochondrial protein dynamics are associated with decreased abundance of the serine-threonine kinase PRKD2 and HSP27 phosphorylated on serines 78 and 82. Cellular defects in HAX1–/– cells can be functionally reconstituted by HSP27. Thus, mitochondrial proteostasis emerges as a critical molecular and metabolic mechanism governing the differentiation and function of neutrophil granulocytes.