Mitochondrial Regulation Research Articles

The suppressive effects of crocin from saffron on allergic airway inflammation through Drp1/Nfr1/Mfn2/Pgc1-alpha signaling pathway in mice

Ethnopharmacological relevanceSaffron is derived from the dried stigmas of Crocus sativus L., which was considered by ancient nations for food and medicinal purposes. In traditional medicine, the therapeutic use of Crocus sativus includes antispasmodic, antitussive and expectorant. Aim of the studyMitochondrial fusion, fission, biogenesis, and mitophagy are essential processes for maintaining mitochondrial dynamics in response to cellular stress. The primary objective of this research was to examine how crocin affected the levels of important mitochondrial regulators, including Drp1, Pgc1α, Nrf1, and Mfn2, in the lung tissue of ovalbumin-sensitized mice. Materials and methodsA total of fifty male BALB/C mice were randomly assigned to five unique groups (n = 10 for each group), including the control group, ovalbumin-sensitized group (OVA), OVA group treated with 30 mg/kg of crocin, OVA group treated with 60 mg/kg of crocin, and OVA group treated with 1 mg/kg of dexamethasone. Post-sensitization and ovalbumin challenge, mice lung tissues were evaluated for the expression of Drp1, Pgc1α, Nrf1, and Mfn2 mRNA levels using real-time PCR as well as histopathological assessments. ResultsIn the OVA group, there was a significant elevated in inflammatory cells such as eosinophils, neutrophils, macrophages, and lymphocytes; however, crocin (both concentrations) and dexamethasone intervention showed significant inhibitory effects (P < 0.01 to P < 0.001). Moreover, an increase in the expression of Drp1, Pgc1α, and Nrf1 levels was seen in the OVA group, while crocin and dexamethasone showed protective benefits (P < 0.05 to P < 0.001). Furthermore, the levels of Mfn2 were reduced in the lung tissue of mice exposed to ovalbumin, but this decrease was reversed by crocin 60 (P < 0.05) and dexamethasone treatment (P < 0.001). ConclusionIn mice with OVA sensitization, the balance of mitochondrial dynamics in lung tissue was disrupted, but intervention of crocin identified to have a protective effect.

The mitochondrial Na+/Ca2+ exchanger NCLX is implied in the activation of hypoxia-inducible factors

Eukaryotic cells and organisms depend on oxygen for basic living functions, and they display a panoply of adaptations to situations in which oxygen availability is diminished (hypoxia). A number of these responses in animals are mediated by changes in gene expression programs directed by hypoxia-inducible factors (HIFs), whose main mechanism of stabilization and functional activation in response to decreased cytosolic oxygen concentration was elucidated two decades ago. Human acute responses to hypoxia have been known for decades, although their precise molecular mechanism for oxygen sensing is not fully understood. It is already known that a redox component, linked with reactive oxygen species (ROS) production of mitochondrial origin, is implied in these responses. We have recently described a mechanism by which the mitochondrial sodium/calcium exchanger, NCLX, participates in mitochondrial electron transport chain regulation and ROS production in response to acute hypoxia.Here we show that NCLX is also implied in the response to hypoxia mediated by the HIFs. By using a NCLX inhibitor and interference RNA we show that NCLX activity is necessary for HIF-α subunits stabilization in hypoxia and for HIF-1-dependent transcriptional activity. We also show that hypoxic mitochondrial ROS production is not required for HIF-1α stabilization under all circumstances, suggesting that the basal cytosolic redox state or other mechanism(s) could be operating in the NCLX-mediated response to hypoxia that operates through HIF-α stabilization. This finding provides a link between acute and medium-term responses to hypoxia, reinforcing a central role of mitochondrial cell signalling in the response to hypoxia.

Mitochondrial dynamics as a potential therapeutic target in acute myeloid leukemia.

Acute myeloid leukemia (AML) cells are highly dependent on oxidative phosphorylation and the mitochondrial dynamics regulated by fusion-related genes MFN1, MFN2, and OPA1 and fission-related genes DNM1L and MFF. An analysis of previously published gene expression datasets showed that high expression of MFF was significantly associated with poor prognosis in patients with AML. Based on this finding, we investigated the impact of mitochondrial dynamics in AML. Transduction of shRNA against fission-related genes, DNM1L and MFF, inhibited growth and increased the mitochondrial area in AML cell lines. Extracellular flux analysis showed that deletion of mitochondrial dynamic regulators reduced mitochondrial respiration without significantly affecting glycolysis, except in shDNM1L-transfected cells. Immunodeficient NOG mice transplanted with DNM1L- or MFF-knockdown AML cells survived significantly longer than controls. Treatment of AML cell lines with Mdivi-1, which inhibits the DRP1 encoded by DNM1L, inhibited cell proliferation and oxidative phosphorylation. Our results show that mitochondrial dynamics play an important role in AML, and provide novel biological insights. The inhibition of mitochondrial dynamics induces unique mitochondrial alterations, which may be explored as a potential therapeutic target in AML.

Recent Advances of Mitochondrial Alterations in Alzheimer's Disease: A Perspective of Mitochondrial Basic Events.

Alzheimer's disease (AD) is one of the most common neurodegenerative disorders and is characterized by a decrease in learning capacity, memory loss and behavioral changes. In addition to the well-recognized amyloid-β cascade hypothesis and hyperphosphorylated Tau hypothesis, accumulating evidence has led to the proposal of the mitochondrial dysfunction hypothesis as the primary etiology of AD. However, the predominant molecular mechanisms underlying the development and progression of AD have not been fully elucidated. Mitochondrial dysfunction is not only considered an early event in AD pathogenesis but is also involved in the whole course of the disease, with numerous pathophysiological processes, including disordered energy metabolism, Ca2+ homeostasis dysfunction and hyperactive oxidative stress. In the current review, we have integrated emerging evidence to summarize the main mitochondrial alterations- bioenergetic metabolism, mitochondrial inheritance, mitobiogenesis, fission- fusion dynamics, mitochondrial degradation, and mitochondrial movement- underlying AD pathogenesis; precisely identified the mitochondrial regulators; discussed the potential mechanisms and primary processes; highlighted the leading players; and noted additional incidental signaling pathway changes. This review may help to stimulate research exploring mitochondrial metabolically-oriented neuroprotection strategies in AD therapies, leading to a better understanding of the link between the mitochondrial dysfunction hypothesis and AD pathogenesis.

Dexamethasone Impairs ATP Production and Mitochondrial Performance in Human Trabecular Meshwork Cells.

Mitochondrial damage occurs in human trabecular meshwork (HTM) cells as a result of normal aging and in open angle glaucoma. Using an HTM cell model, we quantified mitochondrial function and ATP generation rates after dexamethasone (Dex) and TGF-β2 treatments, frequently used as in vitro models of glaucoma. Primary HTM cells were assayed for metabolic function using a Seahorse XFp Analyzer. We additionally assessed the mitochondrial copy number and the expression of transcripts associated with mitochondrial biogenesis and oxidative stress regulation. Cells treated with Dex, but not TGF-β2, exhibited a significant decrease in total ATP production and ATP from oxidative phosphorylation relative to that of the control. Dex treatment also resulted in significant decreases in maximal respiration, ATP-linked O2 consumption, and non-mitochondrial O2 consumption. We did not observe significant changes in the level of mitochondrial genomes or mRNA transcripts of genes involved in mitochondrial biogenesis and oxidative stress regulation. Decreased mitochondrial performance and ATP production are consistent with the results of prior studies identifying the effects of Dex on multiple cell types, including HTM cells. Our results are also consistent with in vivo evidence of mitochondrial damage in open-angle glaucoma. Overall, these results demonstrate a decrease in mitochondrial performance in Dex-induced glaucomatous models in vitro, meriting further investigation.

Parallel genome-scale CRISPR-Cas9 screens uncouple human pluripotent stem cell identity versus fitness.

Pluripotent stem cells are defined by their self-renewal capacity, which is the ability of the stem cells to proliferate indefinitely while maintaining the pluripotent identity essential for their ability to differentiate into any somatic cell lineage. However, understanding the mechanisms that control stem cell fitness versus the pluripotent cell identity is challenging. To investigate the interplay between these two aspects of pluripotency, we performed four parallel genome-scale CRISPR-Cas9 loss-of-function screens interrogating stem cell fitness in hPSC self-renewal conditions, and the dissolution of the primed pluripotency identity during early differentiation. Comparative analyses led to the discovery of genes with distinct roles in pluripotency regulation, including mitochondrial and metabolism regulators crucial for stem cell fitness, and chromatin regulators that control pluripotent identity during early differentiation. We further discovered a core set of factors that control both stem cell fitness and pluripotent identity, including a network of chromatin factors that safeguard pluripotency. Our unbiased and systematic screening and comparative analyses disentangle two interconnected aspects of pluripotency, provide rich datasets for exploring pluripotent cell identity versus cell fitness, and offer a valuable model for categorizing gene function in broad biological contexts.

Betaine delays age-related muscle loss by mitigating Mss51-induced impairment in mitochondrial respiration via Yin Yang1.

Mitochondrial dysfunction is one of the hallmarks of aging and a leading contributor to sarcopenia. Nutrients are essential for improving mitochondrial function and skeletal muscle health during the aging process. Betaine is a nutrient with potential muscle-preserving properties. However, whether and how betaine could regulate the mitochondria function in aging muscle are poorly understood. We aimed to explore the molecular target and underlying mechanism of betaine in attenuating the age-related mitochondrial dysfunction in skeletal muscle. Young mice (YOU, 2months), old mice (OLD, 15months), and old mice with betaine treatment (BET, 15months) were fed for 12weeks. The effects of betaine on muscle mass, strength, function, and subcellular structure of muscle fibres were assessed. RNA sequencing (RNA-seq) was conducted to identify the molecular target of betaine. The impacts of betaine on mitochondrial-related molecules, superoxide accumulation, and oxidative respiration were examined using western blotting (WB), immunofluorescence (IF) and seahorse assay. The underlying mechanism of betaine regulation on the molecular target to maintain mitochondrial function was investigated by luciferase reporter assay, chromatin immunoprecipitation and electrophoretic mobility shift assay. Adenoassociated virus transfection, succinate dehydrogenase staining (SDH), and energy expenditure assessment were performed on 20-month-old mice for validating the mechanism in vivo. Betaine intervention demonstrated anti-aging effects on the muscle mass (P=0.017), strength (P=0.010), and running distance (P=0.013). Mitochondrial-related markers (ATP5a, Sdha, and Uqcrc2) were 1.1- to 1.5-fold higher in BET than OLD (all P≤0.036) with less wasted mitochondrial vacuoles accumulating in sarcomere. Bioinformatic analysis from RNA-seq displayed pathways related to mitochondrial respiration activity was higher enriched in BET group (NES=-0.87, FDR=0.10). The quantitative real time PCR (qRT-PCR) revealed betaine significantly reduced the expression of a novel mitochondrial regulator, Mss51 (-24.9%, P=0.002). In C2C12 cells, betaine restored the Mss51-mediated suppression in mitochondrial respiration proteins (all P≤0.041), attenuated oxygen consumption impairment, and superoxide accumulation (by 20.7%, P=0.001). Mechanically, betaine attenuated aging-induced repression in Yy1 mRNA expression (BET vs. OLD: 2.06 vs. 1.02, P=0.009). Yy1 transcriptionally suppressed Mss51 mRNA expression both in vitro and in vivo. This contributed to the preservation of mitochondrial respiration, improvement for energy expenditure (P=0.008), and delay of muscle loss during aging process. Altogether, betaine transcriptionally represses Mss51 via Yy1, improving age-related mitochondrial respiration in skeletal muscle. These findings suggest betaine holds promise as a dietary supplement to delay skeletal muscle degeneration and improve age-related mitochondrial diseases.

Mitochondrial regulation of muscle stem cells in diseases and aging

Mitochondrial regulation of muscle stem cells in diseases and aging

Impact of exercise and fasting on mitochondrial regulators in human muscle

Abstract Objectives To investigate the impact of acute energetic stress (acute HIIE and fasting) on ERRγ, PPARβ, NR1D1, NR4A1, and TFEB in human skeletal muscle. Methods The current study performed secondary analyses using muscle biopsy samples from two previously published studies: study 1) leg muscle biopsies from nine men and eight women were obtained pre and 3 h following acute high-intensity interval cycling exercise (HIIE); study 2) leg muscle biopsies were obtained from nine men pre-, during, and post-an 8 h fast with or without 2 h of arm ergometer exercise. RT-PCR was performed on samples from each study to determine the mRNA expression of ERRγ, PPARβ, NR1D1, NR4A1, and TFEB. Additionally, we retrieved data from meta-analyzed human muscle gene expression using the publicly available database MetaMex. Results PGC-1α (p&lt;0.01, d=1.98) and NR4A1 (p&lt;0.01, d=1.36) mRNA expression significantly increased while TFEB (p≤0.05, d=0.70) decreased following HIIE. Significant decreases in NR4A1 and NR1D1 mRNA expression were observed following an 8 h fast. Our MetaMex analyses revealed significant increases (p&lt;0.05) in PGC-1α and NR4A1 expression following aerobic and resistance exercise, and in PPARβ expression following resistance exercise. Conclusions Our data indicate that acute HIIE stimulates increases in NR4A1 and PGC-1α and decreases in TFEB mRNA expression in human skeletal muscle. Additionally, a short term (8 h) fast reduced the mRNA expression of the transcriptional regulators NR4A1 and NR1D1 – potentially as a mechanism of decreasing mitochondrial biogenesis to reduce energy expenditure during a period of restricted energy availability.

Mitigation of Deoxynivalenol (DON)- and Aflatoxin B1 (AFB1)-Induced Immune Dysfunction and Apoptosis in Mouse Spleen by Curcumin.

In the context of the potential immunomodulatory properties of curcumin in counteracting the detrimental effects of concurrent exposure to Deoxynivalenol (DON) and Aflatoxin B1 (AFB1), a comprehensive 28-days trial was conducted utilizing 60 randomly allocated mice divided into four groups. Administration of curcumin at a dosage of 5 mg/kg body weight in conjunction with DON at 0.1 mg/kg and AFB1 at 0.01 mg/kg body weight was undertaken to assess its efficacy. Results indicated that curcumin intervention demonstrated mitigation of splenic structural damage, augmentation of serum immunoglobulin A (IgA) and immunoglobulin G (IgG) levels, elevation in T lymphocyte subset levels, and enhancement in the mRNA expression levels of pro-inflammatory cytokines TNF-α, IFN-γ, IL-2, and IL-6. Furthermore, curcumin exhibited a suppressive effect on apoptosis in mice, as evidenced by decreased activity of caspase-3 and caspase-9, reduced expression levels of pro-apoptotic markers Bax and Cytochrome-c (Cyt-c) at both the protein and mRNA levels, and the maintenance of a balanced expression ratio of mitochondrial apoptotic regulators Bax and Bcl-2. Collectively, these findings offer novel insights into the therapeutic promise of curcumin in mitigating immunosuppression and apoptotic events triggered by mycotoxin co-exposure.

Mitochondrial Dynamics in Non-Small Cell Lung Cancer.

In lung cancer patients, two complementary abnormalities were found that can cause disruption of the mitochondrial network: increased fusion and impaired fission, manifested by reduced levels of FIS1, a mitochondrial division regulator, and increased expression of MFN1, a mitochondrial fusion mediator. Immunoexpression studies of MFN1 and FIS1 proteins were performed in serum samples obtained from 47 patients with non-small cell lung cancer (NSCLC) and 21 controls. In the NSCLC patients, the immunoexpression of the MFN1 protein was significantly higher, and the FIS1 protein level was significantly lower than in the control group (p < 0.01; p < 0.001; UMW test). Patients with early, operable lung cancer had significantly lower levels of MFN1 immunoexpression compared to patients with advanced, metastatic lung cancer (p < 0.05; UMW test). This suggests that early stages of the disease are characterized by greater fragmentation of damaged mitochondria and apoptosis. In contrast, lower FIS1 protein levels were associated with a worse prognosis. Increased mitochondrial fusion in the blood of lung cancer patients may suggest an increase in protective and repair mechanisms. This opens up questions about why these mechanisms fail in the context of existing advanced cancer disease and is a starting point for further research into why protective mechanisms fail in lung cancer patients.

The new pattern for dual NOTCH pathway involving nuclear transcription and mitochondrial regulation supports therapeutic mechanism of 4-butyl benzophenone derivatives against SIRS

The systemic inflammatory response syndrome (SIRS) represents a self-amplifying cascade of inflammatory reactions and pathophysiological states triggered by infectious or non-infectious factors. The identification of disease targets and differential proteins in the liver (the unique and important immune organ) of SIRS mice treated with the lead compound D1 was conducted using the Genecards database and proteomic analysis, respectively. Subsequently, NOTCH1 was identified as the potential hub target via an intersection analysis between the aforementioned differentially expressed proteins and disease targets. Based on our previous research on the structure-activity relationship, we designed and synthesized a series of SIRS-related derivatives, wherein butyl, halogen, and ester groups were incorporated into benzophenone, aiming at exploring the anti-inflammatory protective action from the perspective of macrophage polarization. Notably, these derivatives exhibited a direct binding capability to the O-glucosylation site (SER496) or its vicinities (such as SER492, VAL485) of NOTCH1 using docking, SPR, DARTS, and CETSA techniques. Mechanistically, derivative D6 exerted anti-inflammatory effects via the dual NOTCH pathway. Firstly, it could inhibit NOTCH1 nuclear transcriptional activity, attenuate the interaction between NICD and RBPJK, concurrently suppress NF-κB and NLRP3 inflammasome (NLRP3, ASC, and cleaved CASP1) activation, and promote NICD (NOTCH1 active fragments) ubiquitination metabolism (the nuclear transcriptional pathway). Secondly, it might possess the ability to increase PGC1α level, subsequently, enhance ATP and MMP levels, mitigate ROS production, increase mitochondrial numbers, and ameliorate mitochondrial inflammatory damage (the mitochondrial pathway). Importantly, the activator Jagged1 could effectively reverse the aforementioned effects, while the inhibitor DAPT exhibited a synergistic effect, suggesting that the nuclear transcriptional regulation and mitochondrial regulation were both in a NOTCH1-dependent manner. Subsequently, it effectively alleviated the inflammatory response and preserved organ function as evidenced by up-regulating M2-type macrophage-related anti-inflammatory cytokines (IL10, TGFβ, CD206, and ARG1) and down-regulating M1-type macrophage-related pro-inflammatory cytokines (NO, IL6, IL18, iNOS, TNFα, CD86, and IL1β). In a word, derivative D6 modulated macrophage polarization and effectively mitigated SIRS by targeting inhibition of the dual NOTCH pathway.

Abstract Tu093: Adeno-associated virus-mediated gene delivery of PERM1 enhances cardiac contractility and mitochondrial biogenesis in mice.

Heart failure remains the leading cause of death in the U.S., and 50% of patients with heart failure still die within 5 years after diagnosis. Mitochondrial impairment and contractile dysfunction are the hallmarks of heart failure with reduced ejection fraction (HFrEF). Yet, there is currently no therapeutic strategy targeting both mitochondria and muscle contractility. PERM1 is a striated-muscle-specific regulator of mitochondrial bioenergetics and is predominantly expressed in the heart and skeletal muscle. Our recent studies demonstrated that PERM1 is downregulated in human and mouse HFrEF hearts and that loss of PERM1 in mice leads to reduced contractility and energy reserve in the heart. However, it is largely unknown whether PERM1 positively regulates both muscle contractility and energetics in the heart. Here, we performed the gene delivery of Perm1 to the heart in C57BL6 wild-type mice (8-12 weeks old) through retro-orbital injection of the adenovirus-associated virus (AAV)9 vector carrying Perm1 (AAV-PERM1). The protein expression levels of PERM1 in the heart was increased by 3 fold as compared with control (mice injected with AAV9-GFP vectors), while there was no change in PERM1 expression in skeletal muscle (n=4/group). Strikingly, AAV-PERM1 mice exhibited a significant increase in ejection fraction (EF) and fractional shortening (FS) (AAV-GFP vs. AAV-PERM1: 0.93 vs. 1.43 and 0.92 vs. 1.64 in DEF and DFS, respectively, both p&lt;0.05 in t-test). In addition, we observed a subtle, yet significant increase in the ratio of the heart weight to tibial length in AAV-PERM1 mice (AAV-GFP vs. AAV-PERM1: 4.7 vs 5.97, p&lt;0.05 in t-test), suggestive of moderate cardiac hypertrophy development. Furthermore, PERM1 overexpression in the heart increased the mitochondrial copy number by 38% as compared to control AAV-GFP mice (p&lt;0.05 in t-test), concurrently with an upregulation of the mitochondrial bioenergetics master regulator PGC-1α (155% of control, p&lt;0.05 in t-test). Overall, these results showed that AAV-mediated PERM1 overexpression simultaneously enhances muscle contractility and mitochondrial biogenesis in the heart. This study further suggests that the gene delivery of PERM1 could be a potential therapeutic approach to treat HFrEF patients.

Abstract We006: Metabolic Reprogramming to Increase Mitochodnrial Mass, Fusion and Energetics Represents an Important Rate Limiting Step in Direct Cardiac Reprogramming

Direct reprogramming of cardiac fibroblasts (CFs) into induced cardiomyocytes (iCMs) shows promise for treating myocardial infarction (MI). However, low conversion efficiency and relative immaturity of iCMs have so far precluded its clinical translation. Native CM maturation and cell cycle exit is associated with a switch from glycolytic metabolism to mitochondrial fatty acid oxidation (FAO), accompanied by a shift in the dynamic balance of mitochondrial fission (dividing) and fusion (joining) toward fusion. Because CFs lack the energy requirements of CMs, we hypothesized that transdifferentiation of CFs to iCMs requires a similar switch. Combining confocal microscopy with metabolic flux assays, we directly compared native CF and CM mitochondrial morphology and energetics. CMs showed significantly higher mitochondrial mass, fusion and energetics, all metrics relevant for increased reliance on mitochondrial FAO. Applying these techniques to study reprogramming, we found that at later reprogramming time points key metrics move significantly toward the phenotypes of native CMs. We then hypothesized that facilitating metabolic reprogramming by inhibiting fission and/or promoting fusion could improve iCM conversion. A loss of function screen identified certain fission genes, particularly the little studied mitochondrial fission regulator 1-like protein (Mtfr1l), as potent barriers to iCM conversion and maturation. In contrast, the core fusion genes were necessary for successful generation of iCMs, particularly the key fusion effector optical atrophy 1 (Opa1). Mtfr1l has been shown to promote cleavage of Opa1, and indeed concurrent knockdown of Opa1 ablated improvements to reprogramming efficiency. In conclusion, we showed both that iCMs are associated with increased mitochondrial mass, fusion and energetics approaching those of native CMs and that inducing CM-like mitochondria by knocking down Mtfr1l dramatically improved reprogramming, potentially through increased fusion activity of Opa1. By incorporating metabolic reprogramming into traditional direct cardiac reprogramming strategies, we may be able to move the field closer to clinical application to improve outcomes after MI.

Abstract We087: The mitochondrial citrate carrier SLC25A1 is a regulator of metabolic reprogramming and morphogenesis in the developing heart

Background: Congenital heart defects (CHDs) are the most common type of birth defect, yet the etiology of most CHDs are unknown. A major genetic risk factor for CHD is 22q11.2 deletion syndrome (22q11.2DS), a multisystem chromosomal microdeletion disorder where ~75% of patients present with CHD. SLC25A1 is a gene found within the 22q11.2DS microdeletion region that encodes for the mitochondrial citrate carrier, an inner membrane transporter that regulates intracellular citrate compartmentalization. Through this role, SLC25A1 is thought to contribute to cytosolic acetyl-CoA availability, and processes like protein acetylation and the epigenetic regulation of gene expression. We have previously found that SLC25A1 is a central gene contributing to the neurodevelopmental presentation of 22q11.2DS and importantly, neuronal mitochondrial function. Because the heart, like the brain, is highly reliant on energy derived from mitochondria, and the developing heart must undergo metabolic maturation whereby metabolism is reprogrammed from primary reliance on glycolysis towards mitochondrial oxidative metabolism, we hypothesized that SLC25A1 plays a key role in the metabolic maturation that is required for proper cardiac development. Objective: Here, we studied the role of Slc25a1 in the developing heart to examine the link between mitochondria and cardiac morphogenesis. Methods and Results: By studying mice with the systemic knockout of SLC25A1, we discovered that Slc25a1 null embryos displayed impaired growth, cardiac malformations, mitochondrial ultrastructural defects and impaired mitochondrial oxygen consumption. Transcriptomics analyses of metabolism-related genes revealed that Slc25a1 deletion causes widespread alterations in metabolic gene expression. Further, metabolic modelling predicted that loss of SLC25A1 downregulates oxidative phosphorylation, while increasing reliance on glucose. Finally, we found that loss of SLC25A1 decreases cardiac H3K9 acetylation levels at promoter regions of dysregulated metabolic genes. Mechanistically, SLC25A1 may regulating mitochondrial function and metabolism through epigenetic control of gene expression to promote metabolic remodeling in the developing heart. Conclusions: Our work suggests that SLC25A1 as an an important mitochondrial regulator of gene expression in the developing heart. Importantly, it positions SLC25A1 as a novel mitochondrial regulator of ventricular morphogenesis as well as cardiac metabolic maturation.

KARS Mutations Impair Brain Myelination by Inducing Oligodendrocyte Deficiency: One Potential Mechanism and Improvement by Melatonin.

It is very crucial to investigate key molecules that are involved in myelination to gain an understanding of brain development and injury. We have reported for the first time that pathogenic variants p.R477H and p.P505S in KARS, which encodes lysyl-tRNA synthetase (LysRS), cause leukoencephalopathy with progressive cognitive impairment in humans. The role and action mechanisms of KARS in brain myelination during development are unknown. Here, we first generated Kars knock-in mouse models throughthe CRISPR-Cas9 system. Kars knock-in mice displayed significant cognitive deficits. These mice also showed significantly reduced myelin density and content, as well as significantly decreased myelin thickness during development. In addition, Kars mutations significantly induced oligodendrocyte differentiation arrest and reduction in the brain white matter of mice. Mechanically, oligodendrocytes' significantly imbalanced expression of differentiation regulators and increased capase-3-mediated apoptosis were observed in the brain white matter of Kars knock-in mice. Furthermore, Kars mutations significantly reduced the aminoacylation and steady-state level of mitochondrial tRNALys and decreased the protein expression of subunits of oxidative phosphorylation complexes in the brain white matter. Kars knock-in mice showed decreased activity of complex IV and significantly reduced ATP production and increased reactive oxygen species in the brain white matter. Significantly increased percentages of abnormal mitochondria and mitochondrion area were observed in the oligodendrocytes of Kars knock-in mouse brain. Finally, melatonin (a mitochondrion protectant) significantly attenuated mitochondrion and oligodendrocyte deficiency in the brain white matter of KarsR504H/P532S mice. The mice treated with melatonin also showed significantly restored myelination and cognitive function. Our study first establishes Kars knock-in mammal models of leukoencephalopathy and cognitive impairment and indicates important roles of KARS in the regulation of mitochondria, oligodendrocyte differentiation and survival, and myelination during brain development and application prospects of melatonin in KARS (or even aaRS)-related diseases.

Metformin alleviates cryoinjuries in porcine oocytes by reducing membrane fluidity through the suppression of mitochondrial activity

Plasma membrane damage in vitrified oocytes is closely linked to mitochondrial dysfunction. However, the mechanism underlying mitochondria-regulated membrane stability is not elucidated. A growing body of evidence indicates that mitochondrial activity plays a pivotal role in cell adaptation. Since mitochondria work at a higher temperature than the constant external temperature of the cell, we hypothesize that suppressing mitochondrial activity would protect oocytes from extreme stimuli during vitrification. Here we show that metformin suppresses mitochondrial activity by reducing mitochondrial temperature. In addition, metformin affects the developmental potential of oocytes and improves the survival rate after vitrification. Transmission electron microscopy results show that mitochondrial abnormalities are markedly reduced in vitrified oocytes pretreated with metformin. Moreover, we find that metformin transiently inhibits mitochondrial activity. Interestingly, metformin pretreatment decreases cell membrane fluidity after vitrification. Furthermore, transcriptome results demonstrate that metformin pretreatment modulates the expression levels of genes involved in fatty acid elongation process, which is further verified by the increased long-chain saturated fatty acid contents in metformin-pretreated vitrified oocytes by lipidomic profile analysis. In summary, our study indicates that metformin alleviates cryoinjuries by reducing membrane fluidity via mitochondrial activity regulation.

In vivo identification of bioactive components of Poria cocos for adjusting mitochondria against metabolic dysfunction-associated fatty liver disease

Currently, no specific treatment exists to alleviate metabolic dysfunction-associated fatty liver (MAFLD). Previously, Poria cocos (PC) effectively relieved MAFLD, but its bioactive components are still unknown. The bioactive substances in PC that regulate mitochondria function to alleviate MAFLD were thus determined. The L02 hepatocyte model induced by fat emulsion and the MAFLD rat model induced by a high-fat diet (HFD) were developed to explore the efficacy of PC against MAFLD. The activity of PC-derived components in the liver mitochondria of HFD-fed rats was evaluated using the L02 hepatocyte model. Additionally, the PC-derived components from the liver mitochondria were identified by ultra-high performance liquid chromatography/mass spectrometry. Finally, the anti-steatosis ability of PC-derived monomers and monomers groups was evaluated using the adipocyte model. PC maintained the mitochondrial ultrastructure, alleviated mitochondrial oxidative stress, and regulated the energy metabolism and the fatty acid β oxidation to relieve lipid emulsion-induced cellular steatosis and HFD-induced MAFLD. PC-derived components entering the liver mitochondria inhibited oxidative stress injury and improved the energy metabolism to fight cellular steatosis. Additionally, 15 chemicals were identified in the PC-treated rat liver mitochondria. These identified chemical molecules and molecule groups in the mitochondria prevented cellular steatosis by regulating mitochondrial oxidative stress and energy metabolism. PC restores mitochondrial structure and function, alleviating MAFLD, which is related to oxidative stress, energy metabolism, and fatty acid β oxidation. The identified 15 components may be the main effective PC components regulating mitochondria function to alleviate MAFLD. Thus, PC may be a promising mitochondrial regulator to prevent MAFLD.

The keratin cytoskeleton emerges as a regulator of mitochondria in the colonic epithelium.

The keratin cytoskeleton emerges as a regulator of mitochondria in the colonic epithelium.

Multiomics of parkinsonism cynomolgus monkeys highlights significance of metabolites in interaction between host and microbiota

The gut microbiota has been demonstrated to play a significant role in the pathogenesis of Parkinson’s disease (PD). However, conflicting findings regarding specific microbial species have been reported, possibly due to confounding factors within human populations. Herein, our current study investigated the interaction between the gut microbiota and host in a non-human primate (NHP) PD model induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) using a multi-omic approach and a self-controlled design. Our transcriptomic sequencing of peripheral blood leukocytes (PBL) identified key genes involved in pro-inflammatory cytokine dysregulation, mitochondrial function regulation, neuroprotection activation, and neurogenesis associated with PD, such as IL1B, ATP1A3, and SLC5A3. The metabolomic profiles in serum and feces consistently exhibited significant alterations, particularly those closely associated with inflammation, mitochondrial dysfunctions and neurodegeneration in PD, such as TUDCA, ethylmalonic acid, and L-homophenylalanine. Furthermore, fecal metagenome analysis revealed gut dysbiosis associated with PD, characterized by a significant decrease in alpha diversity and altered commensals, particularly species such as Streptococcus, Butyrivibrio, and Clostridium. Additionally, significant correlations were observed between PD-associated microbes and metabolites, such as sphingomyelin and phospholipids. Importantly, PDPC significantly reduced in both PD monkey feces and serum, exhibiting strong correlation with PD-associated genes and microbes, such as SLC5A3 and Butyrivibrio species. Moreover, such multi-omic differential biomarkers were linked to the clinical rating scales of PD monkeys. Our findings provided novel insights into understanding the potential role of key metabolites in the host-microbiota interaction involved in PD pathogenesis.