Mitochondrial Disease Research Articles

Phase 2b program with sonlicromanol in patients with mitochondrial disease due to m.3243A>G mutation.

Mitochondrial disease is a group of rare conditions, with no approved treatment to date, except for Leber hereditary optic neuropathy. Therapeutic options to alleviate the symptoms of mitochondrial disease are urgently needed. Sonlicromanol is a promising candidate, as it positively alters the key metabolic and inflammatory pathways associated with mitochondrial disease. Sonlicromanol is a reductive and oxidative distress modulator, selectively inhibiting microsomal prostaglandin E1 synthase activity. This Phase 2b program, aiming at evaluating sonlicromanol in adults with m.3243A>G mutation and primary mitochondrial disease, consisted of a randomized controlled (RCT) study (dose-selection) followed by a 52-week open-label extension study (EXT, long-term tolerability, safety, and efficacy of sonlicromanol). Patients were randomized (1:1:1) to receive 100- or 50-mg sonlicromanol, or placebo twice daily (bid) for 28 days with ≥2-week wash-out period between treatments. Patients who completed the RCT study entered the EXT study wherein they received 100-mg sonlicromanol bid. Overall, 27 patients were randomized (24 RCT patients completed all periods). 15 patients entered the EXT, and 12 patients were included in the EXT analysis set. All patients reported good tolerability and favourable safety, with pharmacokinetic results comparable to the earlier Phase 2a study. The RCT primary endpoint (change from placebo in the attentional domain of cognition score [IDN: visual identification, Cogstate]) did not reach statistical significance. Using a categorisation of the subject's period baseline a treatment effect over placebo was observed if their baseline was more affected (p=0.0338). Using this approach, there were signals of improvements over placebo in at least one dose in the Beck Depression Inventory (BDI, p=0.0143), Cognitive Failure Questionnaire (CFQ, p=0.0113), and the Depression subscale of the Hospital Anxiety and Depression Scale (p=0.0256). Statistically and/or clinically meaningful improvements were observed in the patient- and clinician-reported outcome measures at the end of the EXT study (Test of attentional performance [TAP] with alarm, p=0.0102; TAP without alarm, p=0.0047; BDI somatic, p=0.0261; BDI Total, p=0.0563; SF12 physical component score, p=0.0008). Seven of nine domains of RAND-Short form-36 like SF-36 pain improved (p=0.0105). Other promising results were observed in Neuro QoL-Fatigue-SF (p=0.0036), MiniBESTest (p=0.0009), McGill Pain Questionnaire (p=0.0105), EQ-5D-5L-VAS (p=0.0213) and EQ-5D-5L-index (p=0.0173). Most patients showed improvement in the 5× sit-to-stand test. Sonlicromanol was well-tolerated and demonstrated a favourable benefit/risk ratio for up to one year. Sonlicromanol was efficacious in patients when affected at baseline, as seen across a variety of clinically relevant domains. Long-term treatment showed more pronounced changes from baseline.

MitoMAMMAL: a genome scale model of mammalian mitochondria predicts cardiac and BAT metabolism

Abstract Motivation Mitochondria perform several essential functions in order to maintain cellular homeostasis and mitochondrial metabolism is inherently flexible to allow correct function in a wide range of tissues. Dysregulated mitochondrial metabolism can therefore affect different tissues in different ways which presents experimental challenges in understanding the pathology of mitochondrial diseases. System-level metabolic modelling is therefore useful in gaining in-depth insights into tissue-specific mitochondrial metabolism, yet despite the mouse being a common model organism used in research, there is currently no mouse specific mitochondrial metabolic model available. Results In this work, building upon the similarity between human and mouse mitochondrial metabolism, we have created mitoMammal, a genome-scale metabolic model that contains human and mouse specific gene-product reaction rules. MitoMammal is therefore able to model mouse and human mitochondrial metabolism. To demonstrate this feature, using an adapted E-Flux algorithm, we first integrated proteomic data extracted from mitochondria of isolated mouse cardiomyocytes and mouse brown adipocyte tissue. We then integrated transcriptomic data from in vitro differentiated human brown adipose cells and modelled the context specific metabolism using flux balance analysis. In all three simulations, mitoMammal made mostly accurate, and some novel predictions relating to energy metabolism in the context of cardiomyocytes and brown adipocytes. This demonstrates its usefulness in research relating to cardiac disease and diabetes in both mouse and human contexts. Availability and implementation MitoMammal is formatted in SBML3. The code required for constraint-based modelling used in this work is implemented in Python 3 and is available as a Jupyter Notebook. The mitoMammal metabolic model, along with Jupyter notebooks and data used in this work are available at: https://gitlab.com/habermann_lab/mitomammal. Supplementary Information Supplementary data are available at Bioinformatics Advances online.

Mitochondrial Dysfunction in Environmental Toxicology: Mechanisms, Impacts, and Health Implications.

Mitochondria, pivotal to cellular metabolism, serve as the primary sources of biological energy and are key regulators of intracellular calcium ion storage, crucial for maintaining cellular calcium homeostasis. Dysfunction in these organelles impairs ATP synthesis, diminishing cellular functionality. Emerging evidence implicates mitochondrial dysfunction in the etiology and progression of diverse diseases. Environmental factors that induce mitochondrial dysregulation raise significant public health concerns, necessitating a nuanced comprehension and classification of mitochondrial-related hazards. This review systematically adopts a toxicological perspective to illuminate the biological functions of mitochondria, offering a comprehensive exploration of how toxicants instigate mitochondrial dysfunction. It delves into the disruption of energy metabolism, the initiation of mitochondrial fragility and autophagy, and the induction of mutations in mitochondrial DNA by mutagens. The overarching objective is to enhance our understanding of the repercussions of mitochondrial damage on human health.

Comprehensive phenotypic assessment of nonsense mutations in mitochondrial ND5 in mice.

Mitochondrial dysfunction induced by mitochondrial DNA (mtDNA) mutations has been implicated in various human diseases. A comprehensive analysis of mitochondrial genetic disorders requires suitable animal models for human disease studies. While gene knockout via premature stop codons is a powerful method for investigating the unique functions of target genes, achieving knockout of mtDNA has been rare. Here, we report the genotypes and phenotypes of heteroplasmic MT-ND5 gene-knockout mice. These mutant mice presented damaged mitochondrial cristae in the cerebral cortex, hippocampal atrophy, and asymmetry, leading to learning and memory abnormalities. Moreover, mutant mice are susceptible to obesity and thermogenetic disorders. We propose that these mtDNA gene-knockdown mice could serve as valuable animal models for studying the MT-ND5 gene and developing therapies for human mitochondrial disorders in the future.

Pathogenic mitochondrial DNA mutations inhibit melanoma metastasis.

Mitochondrial DNA (mtDNA) mutations are frequent in cancer, yet their precise role in cancer progression remains debated. To functionally evaluate the impact of mtDNA variants on tumor growth and metastasis, we developed an enhanced cytoplasmic hybrid (cybrid) generation protocol and established isogenic human melanoma cybrid lines with wild-type mtDNA or pathogenic mtDNA mutations with partial or complete loss of mitochondrial oxidative function. Cybrids with homoplasmic levels of pathogenic mtDNA reliably established tumors despite dysfunctional oxidative phosphorylation. However, these mtDNA variants disrupted spontaneous metastasis from primary tumors and reduced the abundance of circulating tumor cells. Migration and invasion of tumor cells were reduced, indicating that entry into circulation is a bottleneck for metastasis amid mtDNA dysfunction. Pathogenic mtDNA did not inhibit organ colonization following intravenous injection. In heteroplasmic cybrid tumors, single-cell analyses revealed selection against pathogenic mtDNA during melanoma growth. Collectively, these findings experimentally demonstrate that functional mtDNA is favored during melanoma growth and supports metastatic entry into the blood.

Sucla2 Knock-Out in Skeletal Muscle Yields Mouse Model of Mitochondrial Myopathy With Muscle Type-Specific Phenotypes.

Pathogenic variants in subunits of succinyl-CoA synthetase (SCS) are associated with mitochondrial encephalomyopathy in humans. SCS catalyses the conversion of succinyl-CoA to succinate coupled with substrate-level phosphorylation of either ADP or GDP in the TCA cycle. This report presents a muscle-specific conditional knock-out (KO) mouse model of Sucla2, the ADP-specific beta subunit of SCS, generating a novel invivo model of mitochondrial myopathy. The mouse model was generated using the Cre-Lox system, with the human skeletal actin (HSA) promoter driving Cre-recombination of a CRISPR-Cas9-generated Sucla2 floxed allele within skeletal muscle. Inactivation of Sucla2 was validated using RT-qPCR and western blot, and both enzyme activity and serum metabolites were quantified by mass spectrometry. To characterize the model invivo, whole-body phenotyping was conducted, with mice undergoing a panel of strength and locomotor behavioural assays. Additionally, exvivo contractility experiments were performed on the soleus (SOL) and extensor digitorum longus (EDL) muscles. SOL and EDL cryosections were also subject to imaging analyses to assess muscle fibre-specific phenotypes. Molecular validation confirmed 68% reduction of Sucla2 transcript within the mutant skeletal muscle (p < 0.001) and 95% functionally reduced SUCLA2 protein (p < 0.0001). By 3 weeks of age, Sucla2 KO mice were 44% the size of controls by body weight (p < 0.0001). Mutant mice also exhibited 34%-40% reduced grip strength (p < 0.01) and reduced spontaneous exercise, spending about 88% less cumulative time on a running wheel (p < 0.0001). Contractile function was also perturbed in a muscle-specific manner; although no genotype-specific deficiencies were seen in EDL function, SUCLA2-deficient SOL muscles generated 40% less specific tetanic force (p < 0.0001), alongside slower contraction and relaxation rates (p < 0.001). Similarly, a SOL-specific threefold increase in mitochondria (p < 0.0001) was observed, with qualitatively increased staining for both COX and SDH, and the proportion of Type 1 myosin heavy chain expressing fibres within the SOL was nearly doubled (95% increase, p < 0.0001) in the Sucla2 KO mice compared with that in controls. SUCLA2 loss within murine skeletal muscle yields a model of SCS-deficient mitochondrial myopathy with reduced body weight, muscle weakness and exercise intolerance. Physiological and morphological analyses of hindlimb muscles showed remarkable differences in exvivo function and cellular consequences between the EDL and SOL muscles, with SOL muscles significantly more impacted by Sucla2 inactivation. This novel model will provide an invaluable tool for investigations of muscle-specific and fibre type-specific pathogenic mechanisms to better understand SCS-deficient myopathy.

Follow-Up of Neonatal Hearing Screening in the Risk Factor Group for Hearing Loss: Results from a Tertiary Medical Center

Introduction: Universal newborn hearing screening has been successfully implemented in many places around the world, and it is recommended that cases with risk factors for hearing loss be followed-up regardless of hearing screening results. However, there is a need for clarity regarding the recommended rate of follow-up and which tests should be performed. The aim of this study was to assess the audiologic follow-up program for the group with risk factors. Method: Our retrospective study involved children of various ages with a risk factor for hearing loss who passed the initial neonatal hearing test but were later diagnosed with hearing loss. Out of 113,708 children born at Hadassah University Medical Center during the years 2013–2021, 6763 were at risk of hearing loss, and their follow-up audiologic test results were studied. Results: Audiologic testing including ABR, OAE, tympanometry and behavioral audiometry was performed in 1534 of 6763 (23%) of the risk factor group that returned to the hospital. In total, 73 children (4.7%) were diagnosed with hearing loss, 54 of whom failed the initial screening and 19 who had passed it. Further examination of the children that passed the initial screening and were later diagnosed with a hearing loss revealed that four cases had been missed in screening (one familial mild hearing loss, one familial progressive loss, one premature infant with a high tone loss, and one NICU graduate with CNS involvement). Another nine cases had late-onset hearing loss (three meningitis, five CMV, and one with a mitochondrial disease). An additional six cases were diagnosed late, and the age of onset of the hearing loss was unknown (two intubated, two with hydrocephalus, one with Cerebral Palsy, and one with general developmental delay). Conclusions: These results reveal the importance of implementing a refined protocol for monitoring hearing in the high-risk group of children that pass neonatal hearing screening with respect to which hearing tests should be conducted, at what age, and the duration of follow-up. Also, barriers to follow-up must be dealt with, and parents should be more involved in the monitoring process.

Lysine and Tryptophan have the Protection Basis against Lysosomal Dysfunction and both PKU and CVD including Mitochondrial Disorder Mediated by Activating Lysosomes and OPA1

The phenylketonuria “PKU” due to sever decreasing in lysine “AAG” and in Lys/ phosphorylation (which necessary for lysosomal digestive function), and associated with sever decreasing in Trp “TGG”, followed by mitochondrial dysfunction and lysosomal dysfunction, that followed by sever decreasing in phe /hydroxylase and in Tyr/ hydroxylase, and followed by decreasing in lysine acylation and in SFACs productiin which followed by decreasing in RA productive pathway and associated with increasing in both of TNFa and cholesterol accumulation which activate increasing in in both of TNFa and NLRP3 pathogenic pathway which reflect decreasing in estrogen synthesis and in dopamine production, that followed by increasing in the risk of ischemic damage pulmonary disease and diabetes. And we can conclude that both of Lys “AAG” and Trp “TGG” are so necessary for activating mitochondrial oxidative functions and necessary for promoting transport system where Mitochondria is so necessary to activate antioxidant function and promoting all of Phe hydroxylase, Tyr hydroxylase, and Lys acylation production which necessary for dopamine and RA synthesis respectively, where the PKU characterized by sever decreasing in antioxidant function, and sever decreasing in both Phe/ hydroxylase &amp; Trp/ hydroxylase production, followed by decreasing in dopamine production and decreasing in retinoic acid production (which due to the reduction in SFACs synthesis). And I concluded that PKU characterized by sever decreasing in Phe /hydroxylase and Tyr /hydroxylase, followed by reduction in dopamine production, and reduction in alpha amylase, that associated with increasing in TNFa and in NLRP3 pathogenic pathway, and associated with increasing in the pulmonary disease and CVD risk. Retionic acid “RA” is regulated by lysine acylation and is regulated by lysine acylation mediated by short fatty acid synthesis, which regulate aminoacyl-tRNAs production regulated by mitochondrial enzymes and regulate mRNA production by E coli (regulated by phenylalanine) that necessary to run antioxidant functions and cellular biosynthesis. The antihypertensive pathway mechanism is: the Lysine →activate ATPase and both lysosomes and Mitochondrial oxidative functions which activate lysine acylation →activate short fatty acid synthesis →stimulate retinoic acid “RA” synthesis - →where both Lys and Trp activate GTPase which promote mitochondria repair and oxidative functions, which activate, Phe/ hydroxylase, and activate Tyr/ hydroxylase which activate dopamine, followed by activating NR4As pathway which responsible for activating GC-beta and both of Oxytocin and Nrf2, followed by Ang2-AT2 and VEGF-A productive functions and heme oxygenase production (notice dopamine regulate heme oxygenase mediated by dopamine beta-hydroxylase which regulated by Mitochondrial oxidative functions) followed by activating anti-inflammatory growth and processes. Lysine Methylation has important role to enhance and adopt hypertension through activating RA and pervious Antihypertensive pathway mediated by Phe/hydroxylase synthesis and Tyr /hydroxylase production followed by activating both of dopamine and NR4As pathway. Where dopamine synthesischaracterized by activating Antioxidant functions that prevent cholesterol accumulation, and in turn increase the estrogen production (which it’s synthesis reflect potential protection from pulmonary disease), and activate the NR4As pathway which regulate all of Oxytocin, Nrf2 production, followed by Ang2-AT2 and VEGF-A production, which followed by activating heme oxygenase and anti-inflammatory growth and processes that prevent LV-hypertrophy, and prevent coronary calcification. Also, the increasing in Lys AAA with decreasing in both of Lys AAG and decreasing Trp TGG will cause decreasing in lysosome proper function, and Pero cause Decreasing in GTPase and decreasing in the Mitochondrial oxidative functions, that will cause decreasing in Phe hydroxylase and in Tyr hydroxylase followed by decreasing in lysine acylation, and associated with increasing in cholesterol accumulation, and also associated with decreasing in both of IL17 production and estrogen functional pathway, that will increase the risk of T2D, pulmonary disease, and increase the risk of PKU and CVD. Both Lys and Trp are necessary to activate transport across cells membranes, that activate antibacterial function and anti-atherosclerosis, mediated by activating lysosomes and OPA1 oxidative functions, where OPA1 functions activated by GTPase productive functions which play important role in activating transport system pathways within and between cells. Lysine acylation is playing important role in activating SFACs production and RA synthesis which protect from pulmonary disease and from ischemic damage. Both Lys and Trp are having the Potency to activate lysosomes and Mitochondrial oxidative functions which activate lipid and protein digestion and enhance Phe /hydroxylase and Tyr / hydroxylase, followed by activating lysine acylation which activate SFACs production and promote the RA synthesis and enhance antioxidant functions and anticoagulant functions, followed by dopamine synthesis and protection against ischemic damage and against both of diabetes, pulmonary disease, CVD , and PKU.

Practical supplements for prevention and management of migraine attacks: a narrative review

BackgroundMigraine is one of the most debilitating neurological disorders that causes frequent attacks of headaches and affects approximately 11% of the global population. Deficient or even insufficient levels of vital nutrients would increase the severity and frequency of migraine attacks. Therefore, we aimed to examine the practical supplements for the prevention and management of migraine attacks.MethodThis narrative review study was conducted by searching PubMed, ISI web of science, EMBASE, Google Scholar, and Scopus using the keywords of “dietary supplement” and “migraine” plus their MeSH terms. Original articles published in English language from their inception to July 27th, 2024, studies that investigated adult population (aged &amp;gt;18 years), and those assessing the impact of intended nutrient supplementation on clinical symptoms of migraine were included in the study.ResultOxidative stress and low intake of antioxidants would be risk factors for migraine attacks by inducing inflammation. The secretion of inflammatory cytokines, such as tumor necrosis factor (TNF)-a, would lead to neuroinflammation and migraine episodes by increasing the cellular permeability and interactions. Evidence also indicated a direct association between phases of migraine attacks and calcitonin gene-related peptide (CGRP), mitochondrial disorders, monoaminergic pathway, disruption in brain energy metabolism, and higher serum levels of glutamate and homocysteine. Therefore, supplementation with nutrients involved in mitochondrial function, brain energy metabolism, and even methyl donors would relieve migraine attacks.ConclusionEvidence indicated that supplementation with riboflavin, omega-3 fatty acids, alpha lipoic acid, magnesium, probiotics, coenzyme Q10, ginger, and caffeine would have favorable effects on migraine patients. However, more prospective studies are required to evaluate the effect of other nutrients on migraine patients.

A New Case of Mitochondrial RNA Helicase SUPV3L1-Associated Neurodegenerative Disease: Ataxia, Spasticity, Optic Atrophy, and Skin Hypopigmentation (ASOASH)

Background: The SUPV3L1 gene encodes ATP-dependent RNA helicase SUPV3L1, which is a part of the mitochondrial degradosome complex or SUV3. SUPV3L1 unwinds secondary structures of mitochondrial RNA (mtRNA) and facilitates the degradation of mtRNA molecules. A nonsense homozygous variant in the SUPV3L1 gene was recently associated with mitochondrial disease. Our study presents the second documented case of SUPV3L1 pathology in humans. Methods: Whole-genome sequencing was performed on the NovaSeq 6000 platform using pair-end reading. Data analysis was performed with an in-house developed pipeline. Results: The 17-year-old female patient exhibited a diverse array of symptoms, including ataxia, spastic paraparesis, cognitive deficit, optic atrophy, and horizontal gaze-evoked nystagmus. Early onset of symptoms, such as ataxic gait and nystagmus, was noted, with subsequent progression of neurological manifestations. At the time of the observation, the proband had extensive regions of hypopigmented skin patches on the body and extremities, which have progressed over time. Whole-genome sequencing revealed compound heterozygous variants in the SUPV3L1 gene: c.272-2A&gt;G and c.1924A&gt;C; p.(Ser642Arg). RNA analysis demonstrated splicing changes attributable to the c.272-2A&gt;G variant. ELISA assay showed increased Complex I content in the patient’s fibroblasts. This case underscores the phenotypic diversity associated with SUPV3L1 mutations, emphasizing the importance of considering mitochondrial RNA helicase dysfunction in the differential diagnosis of neurodegenerative disorders. Further elucidation of the molecular mechanisms underlying SUPV3L1-associated pathology may provide valuable insights into targeted therapeutic interventions.

Endocrine disorders in Kearns-Sayre syndrome with different severity of symptoms: two case reports and a literature review.

Kearns-Sayre Syndrome (KSS) is a variant of mitochondrial disorder caused by a Mitochondrial Deoxyribonucleic Acid (mtDNA) deletion. Clinical manifestations of KSS can include different organ and system involvement. Different organ malfunctions, more often cardiac dysfunction, can lead to death. No effective treatment of this condition exists to date. Here, we report two patients with KSS. Female patient with a large-scale deletion of 7,020 base pairs (bp) suffered from hypogonadism, diabetes mellitus with fluctuating glucose levels, and had poor general health. A male patient with a common 4,977 bp deletion did not have diabetes mellitus but had impaired glucose tolerance. He also had a higher level of general health than our female patient. Both patients had reduced Bone Mineral Density (BMD). In female patients, calcium and vitamin D supplementation combined with metabolic therapy and nutritional drink supplements helped increase BMD (up to 32% in L1-L4). Comparing these two patients suggests that the larger the mtDNA deletion is, the more severe the course of the disease is. Not only does the size of the mtDNA deletion probably determine the severity of the disease, but also such factors as mtDNA heteroplasmy level, presence of mtDNA duplications, and pleioplasmy. Moreover, continuous nonconsecutive metabolic therapy and nutritional supplements are helpful in the prevention of deterioration of symptoms and general health.

Mitochondrial dysfunction is a key link involved in the pathogenesis of sick sinus syndrome: a review

Sick sinus syndrome (SSS) is a grave medical condition that can precipitate sudden death. The pathogenesis of SSS remains incompletely understood. Existing research postulates that the fundamental mechanism involves increased fibrosis of the sinoatrial node and its surrounding tissues, as well as disturbances in the coupled-clock system, comprising the membrane clock and the Ca2+ clock. Mitochondrial dysfunction exacerbates regional tissue fibrosis and disrupts the functioning of both the membrane and calcium clocks. This plays a crucial role in the underlying pathophysiology of SSS, including mitochondrial energy metabolism disorders, mitochondrial oxidative stress damage, calcium overload, and mitochondrial quality control disorders. Elucidating the mitochondrial mechanisms involved in the pathophysiology of SSS and further investigating the disease's mechanisms is of great significance.

COX15 deficiency causes oocyte ferroptosis

Mitochondria play diverse roles in mammalian physiology. The architecture, activity, and physiological functions of mitochondria in oocytes are largely different from those in somatic cells, but the mitochondrial proteins related to oocyte quality and reproductive longevity remain largely unknown. Here, using whole-exome sequencing data from 1,024 women (characterized by oocyte maturation arrest and degenerated or morphologically abnormal oocytes) and 2,868 healthy controls, we performed a population and gene-based burden test for mitochondrial genes and identified a candidate gene, cytochrome c oxidase assembly protein 15 (COX15). We report that biallelic COX15 pathogenic variants cause human oocyte ferroptosis and female infertility in a recessive inheritance pattern. COX15 variants impaired mitochondrial respiration in Saccharomyces cerevisiae and led to reduced protein levels in HeLa cells. Oocyte-specific deletion of Cox15 led to impaired Fe2+ and reactive oxygen species homeostasis that caused mitochondrial dysfunction and ultimately sensitized oocytes to ferroptosis. In addition, ferrostatin-1 (an inhibitor of ferroptosis) could rescue the oocyte ferroptosis phenotype in vitro and ex vivo. Our findings not only provide a genetic diagnostic marker for oocyte development defects but also expand the spectrum of mitochondrial disorders to female infertility and contribute to unique insights into the role of ferroptosis in human oocyte defects.

Characterization of mitochondrial DNA mutations in colorectal cancer progression by in silico approach and use as potential biomarkers for diagnosis and prognosis

BackgroundMitochondrial DNA variants are significant contributors to cancer progression, as evidenced by numerous findings. This study focuses on characterizing mitochondrial DNA mutations in colorectal cancer progression and their potential as biomarkers.MethodologyNext generation sequencing technology was employed to analyze mitochondrial DNA variants in tumor and adjacent normal tissues from 25 patients with colon/rectal cancer. In silico prediction tools (SIFT, Polyphen2, Mutation Assessor, and SNP&GO) were utilized to assess the pathogenicity of these variants. Additionally, homology modeling of mutated protein structures was conducted, and molecular dynamic simulations were performed to assess the impact of mutation on protein function.ResultsEighteen variants were identified across most tumor tissue samples, located in genes from Complex I, IV, and V. Among the identified variants, the V302M and S461 mutations in the MT-ND5 gene and L137F and L220P mutations in the ATP6 gene were predicted to be deleterious, potentially affecting protein function. 3D structural analysis of both wild-type and mutant proteins of MT-ND5 revealed changes in flexibility for the V302M and S461G mutations. The MT-ATP6 mutations L135F and L220P disrupt the interactions with surrounding residues and affect the overall function of protein. Further changes in protein dynamics of the mutated proteins by molecular dynamic simulations also indicate the effects; the mutations have on protein function.ConclusionMT-ND5 and MT-ATP6 variants could serve as potential biomarkers and drug targets in colorectal cancer. This study underscores the significance of mitochondrial DNA variants in cancer progression.

Nicorandil activates lkb1-ampk signaling pathway to ameliorate cardiac remodeling after myocardial ischemia/reperfusion injury by upregulating mt2

Abstract Background Cardiomyocyte apoptosis is a crucial event underlying the development of cardiac abnormalities and dysfunction after myocardial ischemia reperfusion (MI/R) injury. A better understanding of the cell signaling pathways involved in cardiac remodeling may support the development of new therapeutic strategies for the treatment of heart failure (HF) after MI/R. Nicorandil, an ATP-sensitive potassium channel opener, could improve mitochondrial damage and reduce oxidative stress，which reduce cardiomyocyte apoptosis. Metallothionein (Mt), reactive oxygen species (ROS) scavenger, which can reduce oxidative stress, also attenuated MI/R-induced autophagy and cell apoptosis. Except as a potassium channel opener, nicorandil may play a cardioprotective role by regulating metallothionein, and its specific mechanism remains to be elucidated. Objective To clarify the protective effect of nicorandil in myocardial ischemia/reperfusion injury, and elucidate the specific mechanism which nicorandil regulate the expression of metallothiosin to reduce myocardial ischemia/reperfusion injury, so as to provide new drug targets or new measures for clinical prevention and treatment of MI/R. Methods A cardiac MI/R injury model was constructed by the ligation of the left anterior descending coronary artery to investigate the underlying molecular mechanisms. The apoptosis of myocardial tissue cells was detected by TUNEL staining. The ultrastructural changes of myocardial tissue were observed by transmission electron microscopy. The expressions of Mt family, mitochondrial dynamics and Glucose metabolism-associated genes were measured by Western blotting and qPCR. The content of ATP was determined by ELISA in heart tissue. AutodockVina was used to evaluate binding energy and interaction patterns between drug candidates and their targets. The protein-protein interaction model was predicted by ZDOCK software. Results Treatment with nicorandil mitigated left ventricular enlargement, improved cardiac dysfunction,reduced myocardial infarcation area and decreased cardiomyocyte apoptosis after I/R. Nicorandil up-regulated the expression of Mt2 and decreased the expressions of Drp-1,p-Drp-1(ser616), while enhanced the expression of Mfn1/2,GLUT4,HK II and MPC II in myocardium. Knockdown of Mt2 decreased the effects of nicorandil on apoptosis and mitochondrial dysfunction after I/R. Mechanistically, nicorandil significantly upregulated the expression of Mt2, which could bound to LKB1 and cause phosphorylation of LKB1, resulting in AMPK-dependent activation. Conclusions Nicorandil significantly upregulated the expression of Mt2, which interacted with LKB1 to promote LKB1 protein phosphorylation, resulting in AMPK-dependent activation and subsequently alleviating I/R-induced mitochondrial dysfunction and energy metabolism disorder, and thereby reducing cardiomyocyte apoptosis, eventually improving I/ R-induced cardiac remodeling and dysfunction.

Advancing cardiac 3D organoid-on-chip: integrating iPSC-derived MELAS syndrome models to study electromechanical synchronicity and cardiac memory using contactless technology

Abstract Background Mitochondrial DNA mutations affect 1:5000 newborns, posing life-threatening risks, especially to high-energy organs such as the brain, heart, and muscles. Mortality rates can reach 71% when cardiomyopathy is present. MELAS syndrome (Mitochondrial Encephalopathy with Lactic Acidosis and Stroke-like Episodes), primarily affecting protein synthesis (MTTL1 gene, tRNALeu(UUR)), disrupts the electron transport chain complex I and is associated with cardiac conduction defects and hypertrophy. Manifesting symptoms typically appear between ages 3 and adulthood, presenting a complex clinical scenario. Human induced pluripotent stem cells (hiPSCs) offer a unique platform for studying cardiac manifestations of this disease when differentiated into cardiomyocytes. Purpose We adopted a highly adaptable in-vitro model, organized in 3D cardioids, to explore potential impairments in electromechanical coupling of cells. Methods We utilized hiPSCs carrying the MELAS mutation and their respective isogenic controls differentiated into cardiomyocytes, cultured in 3D cardioids. Electromechanical coupling was assessed using laser-poration technology combined with video kinematics evaluation under various stimulation patterns. Results Morphological analysis revealed a statistically significant reduction in the diameter of MELAS cardioids compared to the isogenic 3D structures (368±17.15 μm vs. 527±36.76 μm). In a spontaneous regimen, MELAS samples exhibited higher beating frequency (0.88±0.28 Hz vs. 0.17±0.05 Hz) and contractile speed (99.35±39.11 μm/s vs. 33.46±5.57 μm/s). Additionally, the response to different electric field stimulation protocols varied significantly, with the isogenic cell line showing better adaptation to sinusoidal stimuli than the pathological one, characterized by rectangular monophasic stimuli. Laser-poration technology, combined with MEA chips and video kinematic evaluation, revealed modulation of electromechanical coupling, affecting action potential upstroke and duration, reducing contraction velocity, and altering electromechanical delay. Furthermore, MELAS hiPSCs and primary cardiomyocytes exhibited reduced protein levels of various OXPHOS subunits (SDHB, ATPB, and COX IV) compared to isogenic controls. The mutated cell line also showed increased ROS production in non-stimulated samples compared to stimulated ones (1.3-fold vs. 1.2-fold), with this difference magnifying after 24 hours from stimulation (1.8-fold vs. 1.3-fold). Conclusions This study characterizes MELAS hiPSCs differentiated into cardiac organoids, offering insight into the cardiac aspect of this complex syndrome. Our findings deepen understanding of the syndrome's cardiac impact and response to extracellular stimuli, potentially benefiting affected tissues. This research defines critical physiological and kinematic parameters for MELAS, paving the way for future investigations.

Neuronal Intranuclear Inclusion Disease Presenting with Acute-Onset Dementia and Cortical Edema: A Case Report

BackgroundNeuronal Intranuclear Inclusion Disease (NIID) is a neurodegenerative disorder characterized by the formation of eosinophilic inclusions in the neurons, visceral and skin cells. The cause is associated with the GGC nucleotide repeat expansion in the NOTCH2NLC gene. The imaging hallmark of NIID is hyperintensities on diffusion-weighted imaging (DWI) at the corticomedullary junction. Clinical manifestations of NIID are highly heterogeneous. Here, we report a case of NIID presenting with acute-onset dementia and cortical edema.Case presentationWe describe an elderly male patient who presented with sudden dementia within a day. Considering the abrupt onset and the stroke history, we initially diagnosed vascular disease. However, further imaging revealed cortical edema in the temporo-parieto-occipital lobes. Blood and cerebrospinal fluid tests ruled out immunological, metabolic, infectious, or neoplastic etiologies. Genetic testing ultimately confirmed the diagnosis of NIID. Intravenous immunoglobulin (IVIG) therapy did not improve the patient’s symptoms; However, about 1 month after treatment, spontaneous improvement was observed. It is noteworthy that 22 months before the onset of cognitive impairment, the patient’s MRI for headaches already exhibited the typical imaging lesions of this disease in the cerebellum paravermal region.ConclusionPatients with encephalopathy syndrome exhibiting imaging features resembling mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS) syndrome or Creutzfeldt-Jakob disease should consider the NIID as differential diagnosis. Chronic headaches and symmetric lesions in the cerebellar paravermal region on MRI may be noteworthy indicators of NIID during non-episodic phases.

Unraveling the molecular determinants of a rare human mitochondrial disorder caused by the P144L mutation of FDX2.

Episodic mitochondrial myopathy with or without optic atrophy and reversible leukoencephalopathy (MEOAL) is a rare, orphan autosomal recessive disorder caused by mutations in ferredoxin-2 (FDX2), which is a [2Fe-2S] cluster-binding protein participating in the formation of iron-sulfur clusters in mitochondria. In this biosynthetic pathway, FDX2 works as electron donor to promote the assembly of both [2Fe-2S] and [4Fe-4S] clusters. A recently identified missense mutation of MEOAL is the homozygous mutation c.431C>T (p.P144L) described in six patients from two unrelated families. This mutation alters a highly conserved proline residue located in a loop of FDX2 that is distant from the [2Fe-2S] cluster. How this Pro to Leu substitution damages iron-sulfur cluster biosynthesis is unknown. In this work, we have first compared the structural, dynamic, cluster binding and redox properties of WT and P144L [2Fe-2S] FDX2 to have clues on how the pathogenic P144L mutation can perturb the FDX2 function. Then, we have investigated the interaction of both WT and P144L [2Fe-2S] FDX2 with its physiological electron donor, ferredoxin reductase FDXR, comparing their electron transfer efficiency and protein-protein recognition patterns. Overall, the data indicate that the pathogenic P144L mutation negatively affects the FDXR-dependent electron transfer pathway from NADPH to FDX2, thereby reducing the capacity of FDX2 in assembling both [2Fe-2S] and [4Fe-4S] clusters. Our study also provided solid molecular evidences on the functional role of the C-terminal tail of FDX2 in the electron transfer between FDX2 and FDXR.

Mitochondrial Dysfunction-Molecular Mechanisms and Potential Treatment approaches of Hepatocellular Carcinoma.

Primary liver cancer (PLC), also known as hepatocellular carcinoma (HCC), is a common type of malignant tumor of the digestive system. Its pathological form has a significant negative impact on the patients' quality of life and ability to work, as well as a significant financial burden on society. Current researches had identified chronic hepatitis B virus infection, aflatoxin B1 exposure, and metabolic dysfunction-associated steatotic liver disease (MASLD) as the main causative factors of HCC. Numerous variables, including inflammatory ones, oxidative stress, apoptosis, autophagy, and others, have been linked to the pathophysiology of HCC. On the other hand, autoimmune regulation, inflammatory response, senescence of the hepatocytes, and mitochondrial dysfunction are all closely related to the pathogenesis of HCC. In fact, a growing number of studies have suggested that mitochondrial dysfunction in hepatocytes may be a key factor in the pathogenesis of HCC. In disorders linked to cancer, mitochondrial dysfunction has gained attention in recent 10years. As the primary producer of adenosine triphosphate (ATP) in liver cells, mitochondria are essential for preserving cell viability and physiological processes. By influencing multiple pathological processes, including mitochondrial fission/fusion, mitophagy, cellular senescence, and cell death, mitochondrial dysfunction contributes to the development of HCC. We review the molecular mechanisms of HCC-associated mitochondrial dysfunction and discuss new directions for quality control of mitochondrial disorders as a treatment for HCC.

Association of LONP1 gene with epilepsy and the sub-regional effect

The LONP1 gene encodes Lon protease, which is responsible for degrading damaged or misfolded proteins and binding mitochondrial DNA. Previously, LONP1 variants have been identified in patients with cerebral, ocular, dental, auricular, and skeletal anomalies (CODAS syndrome) and mitochondrial diseases. Seizures were occasionally observed. However, the association between LONP1 and epilepsy remains elusive. In this study, we performed trio-based whole-exome sequencing in a cohort of 450 patients with unexplained epilepsy and identified four pairs of compound heterozygous LONP1 variants in four unrelated cases. All patients exhibited good responses to anti-seizure medications and demonstrated no developmental delay or intellectual disabilities. The variant allele frequencies observed in this study were absent or low in the general population and were significantly lower than those of benign variants. At least one variant in each biallelic pair affected hydrogen bonding and/or altered protein stability. The CODAS syndrome-associated variants were concentrated in the AAA+ module, especially the α domain. Four of the five mitochondrial disease-associated variants were located in the AAA + domain and the NTD5H and NTD3H subdomains. In contrast, each of the biallelic variants from the patients with pure epilepsy had one variant located in the linker domain, and the other variant located in the mitochondrial targeting sequence or P domain. This study suggested that LONP1 gene is potentially a novel candidate gene for pure epilepsy. The phenotypic variation is associated with the sub-regional effects of variants.