Mitochondrial Stress Response Research Articles

The Toxoplasma gondii homolog of ATPase inhibitory factor 1 is critical for mitochondrial cristae maintenance and stress response.

The production of energy in the form of ATP by the mitochondrial ATP synthase must be tightly controlled. One well-conserved form of regulation is mediated via ATPase inhibitory factor 1 (IF1), which governs ATP synthase activity and gene expression patterns through a cytoprotective process known as mitohormesis. In apicomplexans, the processes regulating ATP synthase activity are not fully elucidated. Using the model apicomplexan Toxoplasma gondii, we found that knockout and overexpression of TgIF1, the structural homolog of IF1, significantly affected gene expression. Additionally, TgIF1 overexpression resulted in the formation of a stable TgIF1 oligomer and increased the presence of higher order ATP synthase oligomers. We also show that parasites lacking TgIF1 exhibit reduced mitochondrial cristae density, and that while TgIF1 levels do not affect growth in conventional culture conditions, they are crucial for parasite survival under hypoxia. Interestingly, TgIF1 overexpression enhances recovery from oxidative stress, suggesting a mitohormetic function. In summary, while TgIF1 does not appear to play a role in ATP synthase regulation under conventional growth conditions, our work uncovers its potential role in adapting to the stressors faced by T. gondii and other apicomplexans throughout their intricate life cycles.

EIF5A controls mitoprotein import by relieving ribosome stalling at TIM50 translocase mRNA.

Efficient import of nuclear-encoded proteins into mitochondria is crucial for proper mitochondrial function. The conserved translation factor eIF5A binds ribosomes, alleviating stalling at polyproline-encoding sequences. eIF5A impacts mitochondrial function across species, though the precise molecular mechanism is unclear. We found that eIF5A depletion in yeast reduces the translation and levels of the TCA cycle and oxidative phosphorylation proteins. Loss of eIF5A causes mitoprotein precursors to accumulate in the cytosol and triggers a mitochondrial import stress response. We identify an essential polyproline protein as a direct target of eIF5A: the mitochondrial inner membrane protein and translocase component Tim50. Thus, eIF5A controls mitochondrial protein import by alleviating ribosome stalling along Tim50 mRNA at the mitochondrial surface. Removal of polyprolines from Tim50 partially rescues the mitochondrial import stress response and translation of oxidative phosphorylation genes. Overall, our findings elucidate how eIF5A impacts the mitochondrial function by promoting efficient translation and reducing ribosome stalling of co-translationally imported proteins, thereby positively impacting the mitochondrial import process.

Neuroprotective Effects of Ascorbic Acid, Vanillic Acid, and Ferulic Acid in Dopaminergic Neurons of Zebrafish.

Background/Objectives: Parkinson's disease (PD) is a debilitating neurodegenerative disease that targets the nigrostriatal dopaminergic (DAnergic) system residing in the human midbrain and is currently incurable. The aim of this study is to investigate the neuroprotective effects of ascorbic acid, vanillic acid, and ferulic acid in a zebrafish model of PD induced by MPTP by assessing the impact of these compounds on DAnergic neurons, focusing on gene expression, mitochondrial dynamics, and cellular stress responses. Methods/Results: Following exposure and qPCR and immunohistochemical analyses, ascorbic acid enhanced DAnergic function, indicated by an upregulation of the dopamine transporter (dat) gene and increased eGFP+ DAnergic cells, suggesting improved dopamine reuptake and neuroprotection. Ascorbic acid also positively affected mitochondrial dynamics and stress response pathways, countering MPTP-induced dysregulation. Vanillic acid only had modest, if any, neuroprotective effects on DAnergic neurons following MPTP administration. Ferulic acid exhibited the largest neuroprotective effects through the modulation of gene expression related to DAnergic neurons and mitochondrial dynamics. Conclusions: These findings suggest that ascorbic acid and ferulic acid can act as potential protective interventions for DAnergic neuron health, demonstrating various beneficial effects at the molecular and cellular levels. However, further investigation is needed to translate these results into clinical applications. This study enhances the understanding of neuroprotective strategies in neurodegenerative diseases, emphasizing the importance of considering interactions between physiological systems.

Mitochondrial-targeted plastoquinone therapy ameliorates early onset muscle weakness that precedes ovarian cancer cachexia in mice.

Cancer cachexia, and the related loss of muscle and strength, worsens quality of life and lowers overall survival. Recently, a novel 'pre-atrophy' muscle weakness was identified during early-stage cancer. While mitochondrial stress responses are associated with early-stage pre-atrophy weakness, a causal relationship has not been established. Using a robust mouse model of metastatic epithelial ovarian cancer (EOC)-induced cachexia, we found the well-established mitochondrial-targeted plastoquinone SkQ1 partially prevents pre-atrophy weakness in the diaphragm. Furthermore, SkQ1 improved force production during atrophy without preventing atrophy itself in the tibialis anterior and diaphragm. EOC reduced flexor digitorum brevis (FDB) force production and myoplasmic free calcium ([Ca 2+ ] i ) during contraction in single muscle fibers, both of which were prevented by SkQ1. Remarkably, changes in mitochondrial reactive oxygen species and pyruvate metabolism were heterogeneous across time and between muscle types which highlights a considerable complexity in the relationships between mitochondria and muscle remodeling throughout EOC. These discoveries identify that muscle weakness can occur independent of atrophy throughout EOC in a manner that is linked to improved calcium handling. The findings also demonstrate that mitochondrial-targeted therapies exert a robust effect in preserving muscle force during the early pre-atrophy period and in late-stage EOC once cachexia has become severe.

ASI-RIM neuronal axis regulates systemic mitochondrial stress response via TGF-β signaling cascade.

Morphogens play a critical role in coordinating stress adaptation and aging across tissues, yet their involvement in neuronal mitochondrial stress responses and systemic effects remains unclear. In this study, we reveal that the transforming growth factor beta (TGF-β) DAF-7 is pivotal in mediating the intestinal mitochondrial unfolded protein response (UPRmt) in Caenorhabditis elegans under neuronal mitochondrial stress. Two ASI sensory neurons produce DAF-7, which targets DAF-1/TGF-β receptors on RIM interneurons to orchestrate a systemic UPRmt response. Remarkably, inducing mitochondrial stress specifically in ASI neurons activates intestinal UPRmt, extends lifespan, enhances pathogen resistance, and reduces both brood size and body fat levels. Furthermore, dopamine positively regulates this UPRmt activation, while GABA acts as a systemic suppressor. This study uncovers the intricate mechanisms of systemic mitochondrial stress regulation, emphasizing the vital role of TGF-β in metabolic adaptations that are crucial for organismal fitness and aging during neuronal mitochondrial stress.

Acute contractile activity induces the activation of the mitochondrial integrated stress response and the transcription factor ATF4.

Skeletal muscle relies on mitochondria to produce energy and support its metabolic flexibility. The function of the mitochondrial pool is regulated by quality control (MQC) processes. The integrated stress response (ISR), a MQC pathway, is activated in response to various cellular stressors. The transcription factor ATF4, the main effector of the ISR, ameliorates cellular stress by upregulating protective genes, such as CHOP and ATF5. Recent literature has shown that the ISR is activated upon mitochondrial stress, however, whether this includes acute exercise-induced stress is poorly defined. To investigate this, a mouse in situ hindlimb protocol was utilized to acutely stimulate muscles at 0.25, 0.5 and 1 tetanic contraction/per second for 9 mins, followed by a 1-hour recovery period. CAMKII and JNK2 were robustly activated 6-fold immediately following the protocol. ISR activation, denoted as the ratio of phosphorylated to total-eIF2a protein levels, was also elevated following recovery. Downstream, contractile activity induced an increase in the nuclear localization of ATF4. Robust 2-fold increases in the mRNA expression of ATF4 and CHOP were also observed following the recovery period. Changes in ATF4 mRNA were independent of transcriptional activation, as assessed using an ATF4 promoter-reporter plasmid. Instead, mRNA decay assays revealed an increase in ATF4 mRNA stability post-contractile activity, as a result of enhanced stabilization by the RNA binding protein, HuR. Thus, acute contractile activity is sufficient to induce mitochondrial stress and activate the ISR, corresponding to the induction of ATF4 with potential consequences for mitochondrial phenotype adaptations in response to repeated exercise.

NAD+-boosting agent nicotinamide mononucleotide potently improves mitochondria stress response in Alzheimer’s disease via ATF4-dependent mitochondrial UPR

Extensive studies indicate that mitochondria dysfunction is pivotal for Alzheimer’s disease (AD) pathogenesis; while cumulative evidence suggests that increased mitochondrial stress response (MSR) may mitigate neurodegeneration in AD, explorations to develop a MSR-targeted therapeutic strategy against AD are scarce. We combined cell biology, molecular biology, and pharmacological approaches to unravel a novel molecular pathway by which NAD+-boosting agent nicotinamide mononucleotide (NMN) regulates MSR in AD models. Here, we report dyshomeostasis plasma UPRmt-mitophagy-mediated MSR profiles in AD patient samples. NMN restores NAD+ metabolic profiles and improves MSR through the ATF4-dependent UPRmt pathway in AD-related cross-species models. At the organismal level, NAD+ repletion with NMN supplementation ameliorates mitochondrial proteotoxicity, decreases hippocampal synaptic disruption, decreases neuronal loss, and brain atrophy in mice model of AD. Remarkably, omics features of the hippocampus with NMN show that NMN leads to transcriptional changes of genes and proteins involved in MSR characteristics, principally within the astrocyte unit rather than microglia and oligodendrocytes. In brief, our work provides evidence that MSR has an active role in the pathogenesis of AD, as reducing mitochondrial homeostasis via atf4 depletion in AD mice aggravates the hallmarks of the disease; conversely, bolstering mitochondrial proteostasis by NMN decreases protein aggregation, restores memory performance, and delays disease progression, ultimately translating to increased healthspan.

DELE1 maintains muscle proteostasis to promote growth and survival in mitochondrial myopathy

Mitochondrial dysfunction causes devastating disorders, including mitochondrial myopathy, but how muscle senses and adapts to mitochondrial dysfunction is not well understood. Here, we used diverse mouse models of mitochondrial myopathy to show that the signal for mitochondrial dysfunction originates within mitochondria. The mitochondrial proteins OMA1 and DELE1 sensed disruption of the inner mitochondrial membrane and, in response, activated the mitochondrial integrated stress response (mt-ISR) to increase the building blocks for protein synthesis. In the absence of the mt-ISR, protein synthesis in muscle was dysregulated causing protein misfolding, and mice with early-onset mitochondrial myopathy failed to grow and survive. The mt-ISR was similar following disruptions in mtDNA maintenance (Tfam knockout) and mitochondrial protein misfolding (CHCHD10 G58R and S59L knockin) but heterogenous among mitochondria-rich tissues, with broad gene expression changes observed in heart and skeletal muscle and limited changes observed in liver and brown adipose tissue. Taken together, our findings identify that the DELE1 mt-ISR mediates a similar response to diverse forms of mitochondrial stress and is critical for maintaining growth and survival in early-onset mitochondrial myopathy.

A germline-to-soma signal triggers an age-related decline of mitochondrial stress response

The abilities of an organism to cope with extrinsic stresses and activate cellular stress responses decline during aging. The signals that modulate stress responses in aged animals remain to be elucidated. Here, we discover that feeding Caenorhabditis elegans (C. elegans) embryo lysates to adult worms enabled the animals to activate the mitochondrial unfolded protein response (UPRmt) upon mitochondrial perturbations. This discovery led to subsequent investigations that unveil a hedgehog-like signal that is transmitted from the germline to the soma in adults to inhibit UPRmt in somatic tissues. Additionally, we find that the levels of germline-expressed piRNAs in adult animals markedly decreased. This reduction in piRNA levels coincides with the production and secretion of a hedgehog-like signal and suppression of the UPRmt in somatic cells. Building upon existing research, our study further elucidates the intricate mechanisms of germline-to-soma signaling and its role in modulating the trade-offs between reproduction and somatic maintenance within the context of organismal aging.

CEAM is a mitochondrial-localized, amyloid-like motif-containing microprotein expressed in human cardiomyocytes

Microproteins synthesized through non-canonical translation pathways are frequently found within mitochondria. However, the functional significance of these mitochondria-localized microproteins in energy-intensive organs such as the heart remains largely unexplored. In this study, we demonstrate that the long non-coding RNA CD63-AS1 encodes a mitochondrial microprotein. Notably, in ribosome profiling data of human hearts, there is a positive correlation between the expression of CD63-AS1 and genes associated with cardiomyopathy. We have termed this microprotein CEAM (CD63-AS1 encoded amyloid-like motif containing microprotein), reflecting its sequence characteristics. Our biochemical assays show that CEAM forms protease-resistant aggregates within mitochondria, whereas deletion of the amyloid-like motif transforms CEAM into a soluble cytosolic protein. Overexpression of CEAM triggers mitochondrial stress responses and adversely affect mitochondrial bioenergetics in cultured cardiomyocytes. In turn, the expression of CEAM is reciprocally inhibited by the activation of mitochondrial stresses induced by oligomycin. When expressed in mouse hearts via adeno-associated virus, CEAM impairs cardiac function. However, under conditions of pressure overload-induced cardiac hypertrophy, CEAM expression appears to offer a protective benefit and mitigates the expression of genes associated with cardiac remodeling, presumably through a mechanism that suppresses stress-induced translation reprogramming. Collectively, our study uncovers a hitherto unexplored amyloid-like microprotein expressed in the human cardiomyocytes, offering novel insights into myocardial hypertrophy pathophysiology.

Unveiling the role of transgelin as a prognostic and therapeutic target in kidney fibrosis via a proteomic approach

Chronic kidney disease (CKD) progression involves tubulointerstitial fibrosis, a process characterized by excessive extracellular matrix accumulation. To identify potential biomarkers for kidney fibrosis, we performed mass spectrometry-based proteomic profiling of human kidney tubular epithelial cells and kidney tissue from a 5/6 nephrectomy rat model. Multidisciplinary analysis across kidney fibrosis models revealed 351 differentially expressed proteins associated with kidney fibrosis, and they were enriched in processes related to the extracellular matrix, kidney aging, and mitochondrial functions. Network analysis of the selected proteins revealed five crucial proteins, of which transgelin emerged as a candidate protein that interacts with known fibrosis-related proteins. Concordantly, the gene expression of transgelin in the kidney tissue from the 5/6 nephrectomy model was elevated. Transgelin expression in kidney tissue gradually increased from intermediate to advanced fibrosis stages in 5/6 Nx rats and mice with unilateral ureteral obstruction. Subsequent validation in kidney tissue and urine samples from patients with CKD confirmed the upregulation of transgelin, particularly under advanced disease stages. Moreover, we investigated whether blocking TAGLN ameliorated kidney fibrosis and reduced reactive oxygen species levels in cellular models. In conclusion, our proteomic approach identified TAGLN as a potential noninvasive biomarker and therapeutic target for CKD-associated kidney fibrosis, suggesting its role in modulating mitochondrial dysfunction and oxidative stress responses.

Signaling Mechanism of Cuproptosis Activating cGAS-STING Immune Pathway.

Copper-mediated programmed cell death, which influences the regulation of tumor progression, is an effective approach for antitumor molecular therapy. Unlike apoptosis, copper complex-induced cuproptosis by lipid-acylated protein aggregation triggers the mitochondrial proteotoxic stress response, which could be associated with immunomodulation. However, it remains a great challenge to understand the distinctive molecular mechanisms that presumably activate immunity by cuproptosis. Here, the new nonlabeling fluorescent molecular tools of Cu-DPPZ-Py+ and Cu-DPPZ-Ph are synthesized and used to investigate the differential immune signaling mechanisms induced by copper-mediated cuproptosis or apoptosis. With Cu-DPPZ-Py+ and Cu-Elesclomol, there is strong evidence that the triggering cuproptosis significantly drives mitochondrial DNA (mtDNA) release to activate innate immunity via cyclic GMP-AMP synthase-stimulation of interferon genes (cGAS-STING), which can improve T cell antitumor immunity in vivo. By contrast, it is observed that Cu-DPPZ-Ph treated tumor cells could release intracellular caspase-3, resulting in apoptosis-associated immunosuppression. This study supports insights into how cuproptosis bridges cGAS-STING immune pathways, contributing to the development of cuproptosis-based antitumor immunotherapy.

Quantitative proteomics of patient fibroblasts reveal biomarkers and diagnostic signatures of mitochondrial disease.

BACKGROUNDMitochondrial diseases belong to the group of inborn errors of metabolism (IEM), with a prevalence of 1 in 2,000-5,000 individuals. They are the most common form of IEM, but, despite advances in next-generation sequencing technologies, almost half of the patients are left genetically undiagnosed.METHODSWe investigated a cohort of 61 patients with defined mitochondrial disease to improve diagnostics, identify biomarkers, and correlate metabolic pathways to specific disease groups. Clinical presentations were structured using human phenotype ontology terms, and mass spectrometry-based proteomics was performed on primary fibroblasts. Additionally, we integrated 6 patients carrying variants of uncertain significance (VUS) to test proteomics as a diagnostic expansion.RESULTSProteomic profiles from patient samples could be classified according to their biochemical and genetic characteristics, with the expression of 5 proteins (GPX4, MORF4L1, MOXD1, MSRA, and TMED9) correlating with the disease cohort, thus acting as putative biomarkers. Pathway analysis showed a deregulation of inflammatory and mitochondrial stress responses. This included the upregulation of glycosphingolipid metabolism and mitochondrial protein import, as well as the downregulation of arachidonic acid metabolism. Furthermore, we could assign pathogenicity to a VUS in MRPS23 by demonstrating the loss of associated mitochondrial ribosome subunits.CONCLUSIONWe established mass spectrometry-based proteomics on patient fibroblasts as a viable and versatile tool for diagnosing patients with mitochondrial disease.FUNDINGThe NovoNordisk Foundation, Knut and Alice Wallenberg Foundation, Wellcome Centre for Mitochondrial Research, UK Medical Research Council, and the UK NHS Highly Specialised Service for Rare Mitochondrial Disorders of Adults and Children.

Overactive mitochondrial DNA replication disrupts perinatal cardiac maturation

High mitochondrial DNA (mtDNA) amount has been reported to be beneficial for resistance and recovery of metabolic stress, while increased mtDNA synthesis activity can drive aging signs. The intriguing contrast of these two mtDNA boosting outcomes prompted us to jointly elevate mtDNA amount and frequency of replication in mice. We report that high activity of mtDNA synthesis inhibits perinatal metabolic maturation of the heart. The offspring of the asymptomatic parental lines are born healthy but manifest dilated cardiomyopathy and cardiac collapse during the first days of life. The pathogenesis, further enhanced by mtDNA mutagenesis, involves prenatal upregulation of mitochondrial integrated stress response and the ferroptosis-inducer MESH1, leading to cardiac fibrosis and cardiomyocyte death after birth. Our evidence indicates that the tight control of mtDNA replication is critical for early cardiac homeostasis. Importantly, ferroptosis sensitivity is a potential targetable mechanism for infantile-onset cardiomyopathy, a common manifestation of mitochondrial diseases.

PPARγ drives mitochondrial stress signaling and the loss of atrial cardiomyocytes in newborn mice exposed to hyperoxia

Diastolic dysfunction is increasingly common in preterm infants exposed to supplemental oxygen (hyperoxia). Previous studies in neonatal mice showed hyperoxia suppresses fatty acid synthesis genes required for proliferation and survival of atrial cardiomyocytes. The loss of atrial cardiomyocytes creates a hypoplastic left atrium that inappropriately fills the left ventricle during diastole. Here, we show that hyperoxia stimulates adenosine monophosphate-activated kinase (AMPK) and peroxisome proliferator activated receptor-gamma (PPARγ) signaling in atrial cardiomyocytes. While both pathways can regulate lipid homeostasis, PPARγ was the primary pathway by which hyperoxia inhibits fatty acid gene expression and inhibits proliferation of mouse atrial HL-1 cells. It also enhanced the toxicity of hyperoxia by increasing expression of activating transcription factor (ATF) 5 and other mitochondrial stress response genes. Silencing PPARγ signaling restored proliferation and survival of HL-1 cells as well as atrial cardiomyocytes in neonatal mice exposed to hyperoxia. Our findings reveal PPARγ enhances the toxicity of hyperoxia on atrial cardiomyocytes, thus suggesting inhibitors of PPARγ signaling may prevent diastolic dysfunction in preterm infants.

Mutant huntingtin impairs neurodevelopment in human brain organoids through CHCHD2-mediated neurometabolic failure

Expansion of the glutamine tract (poly-Q) in the protein huntingtin (HTT) causes the neurodegenerative disorder Huntington’s disease (HD). Emerging evidence suggests that mutant HTT (mHTT) disrupts brain development. To gain mechanistic insights into the neurodevelopmental impact of human mHTT, we engineered male induced pluripotent stem cells to introduce a biallelic or monoallelic mutant 70Q expansion or to remove the poly-Q tract of HTT. The introduction of a 70Q mutation caused aberrant development of cerebral organoids with loss of neural progenitor organization. The early neurodevelopmental signature of mHTT highlighted the dysregulation of the protein coiled-coil-helix-coiled-coil-helix domain containing 2 (CHCHD2), a transcription factor involved in mitochondrial integrated stress response. CHCHD2 repression was associated with abnormal mitochondrial morpho-dynamics that was reverted upon overexpression of CHCHD2. Removing the poly-Q tract from HTT normalized CHCHD2 levels and corrected key mitochondrial defects. Hence, mHTT-mediated disruption of human neurodevelopment is paralleled by aberrant neurometabolic programming mediated by dysregulation of CHCHD2, which could then serve as an early interventional target for HD.

Mitochondrial DNA damage, repair and copy number dynamics of Sclerophytum sp. (Anthozoa: Octocorallia) in response to short-term abiotic oxidative stress

As a consequence of global climate change, the increasing frequency of environmental disturbances and surplus oxidative stress experienced by coral reefs will likely contribute to phase shifts from stony to soft corals. Mitochondrial response to reactive oxygen species (ROS) -induced oxidative damage appears pivotal for bioenergetic adaptation and recovery during environmental stress, partly governed by mitochondrial DNA copy number. Unlike other animals, octocorals possess unique mitogenomes with an intrinsic DNA mismatch repair gene, the mtMutS, that is likely to have a role in mitochondrial response and mtDNA damage recovery. Yet, there is a general lack of stress response studies on octocorals from a mitochondrial perspective. Here we evaluate the mitochondrial response of the octocoral Sclerophytum sp. subjected to acute elevated temperature and low pH, and its putative competence to reverse oxidative mtDNA damage caused by exogenous agents like hydrogen peroxide (H2O2). Temporal changes in mtDNA copy number and mtDNA damage and recovery were monitored. Both short-term thermal and low pH stress applied independently instigated mtDNA damage and affected mtDNA copy number differently, while mtMutS gene was significantly upregulated during low pH stress. mtDNA damage caused by H2O2 insult was observed to be promptly reversed in Sclerophytum sp., and a higher mtDNA copy number was associated with lower mtDNA damage. These findings provide insights into the potential role of mtMutS gene in conferring resilience to octocorals, the relevance of mtDNA copy number, and emphasize the importance of better understanding the mitochondrial stress response of cnidarians in the context of climate change.

The Toxoplasma gondii homolog of ATPase inhibitory factor 1 is critical for mitochondrial cristae maintenance and stress response.

The production of energy in the form of ATP by the mitochondrial ATP synthase must be tightly controlled. One well-conserved form of regulation is mediated via ATPase inhibitory factor 1 (IF1), which governs ATP synthase activity and gene expression patterns through a cytoprotective process known as mitohormesis. In apicomplexans, the processes regulating ATP synthase activity are not fully elucidated. Using the model apicomplexan Toxoplasma gondii, we found that knockout and overexpression of TgIF1, the structural homolog of IF1, significantly affected gene expression. Additionally, TgIF1 overexpression resulted in the formation of a stable TgIF1 oligomer that increased the presence of higher order ATP synthase oligomers. We also show that parasites lacking TgIF1 exhibit reduced mitochondrial cristae density, and that while TgIF1 levels do not affect growth in conventional culture conditions, they are crucial for parasite survival under hypoxia. Interestingly, TgIF1 overexpression enhances recovery from oxidative stress, suggesting a mitohormetic function. In summary, while TgIF1 does not appear to play a role in metabolic regulation under conventional growth conditions, our work highlights its importance for adapting to stressors faced by T. gondii and other apicomplexans throughout their intricate life cycles.

Mitochondrial dysfunction and NDUFS3: Insights from a PINK1B9 Drosophila model in Parkinson’s disease pathogenesis

PTEN-induced kinase1 (PINK1) mutation is the main cause of autosomal recessive inheritance and early-onset Parkinson’s disease. Mitochondrial respiratory chain complex I (CI) functional impairment has been considered to be an important factor in the pathogenesis of PD in recent years. In addition, NDUFS3 (nicotinamide adenine dinucleotide deoxylase iron-thionein 3) is one of the core subunits of mitochondrial CI. Therefore, this study explored the role of NDUFS3 gene in PINK1B9 transgenic Drosophila and its possible related mechanisms. In this study, the PD transgenic Drosophila model of MHC-Gal4/UAS system was selected to specifically activate the expression of PINK1B9 gene in the chest muscle tissue of Drosophila melanogaster. NDUFS3 RNAi interference was used to interfere with PINK1B9 transgenic Drosophila melanogaster and its effect on PD transgenic flies was studied. The results suggest that down-regulation of NDUFS3 gene expression may have a protective effect on PINK1B9 transgenic Drosophila melanogaster, and we speculate that down-regulation of NDUFS3 gene expression to reduce oxidative stress and restore mitochondrial function may be related to mitochondrial stress response.

Abstract Tu044: Cardiac Mitochondrial Dysfunction Induces Region-Specific Mitochondrial Stress Response In The Brain To Adapt Neuronal Changes

Background: The hippocampus and cortex are susceptible to changes in blood supply, metabolites, and oxygenation. However, how disrupted cardiac function affects these critical areas of the brain, leading to the cognitive and neurological consequences of heart failure, remains unclear. Hypothesis: We hypothesize that disrupted cardiac function cross-talks with the brain by inducing region-specific mitochondrial stress responses, leading to adaptive changes. Methods: We utilized cardiac-specific LonP1 knockout (LonP1cKO) mice to induce heart failure within 21 days of birth. Alongside cre- control mice, we assessed cerebral blood flow using Laser speckle contrast imaging, locomotor activity through a comprehensive laboratory animal monitoring system (CLAMS), and gene expression profiles in the hippocampus and cortex by RT-PCR. Student’s ‘t’ test determined statistical significance with a p-value<0.05. Results: At 21 days, LonP1cKO mice demonstrated a significant (p<0.0001) reduction in cerebral blood flow (587.1±33.68, n=7) compared to the control (1034±31.26, n=5). Additionally, there were notable decreases in both X and Y-axis ambulatory and total locomotor activities in LonP1cKO mice [XAMB (100.3±6.6 vs 224±13.6 n=16), YAMB) (67.9±4.7 vs 150±8.5 n=16), XTOT (351.8±18.1 vs 534.4±26.3 n=16) and YTOT (190.7±9.6 vs 354.9±17.07 n=16). RT-PCR analysis revealed significant upregulation of genes related to hypoxia and cellular stress (Hif1a, FGf2, Atf6), mitochondrial biogenesis (mtDNA, Tfam, mt-COI, mt-COII), mitochondrial stress response proteases (LonP1, Afg3l2, Spg7, Yme1l1), and downregulation in neurotrophic factors (Bdnf, Ngf, Gfap) in the hippocampus and cortex. Conclusion: The study highlights that cardiac dysfunction in LonP1cKO mice leads to mitochondrial and cellular stress response in the brain to adapt neuronal changes, suggesting a critical link between cardiac health and brain function regulated through mitochondrial stress response pathways.