bims-mitmed Biomed News
on Mitochondrial medicine
Issue of 2022‒11‒27
forty-one papers selected by
Dario Brunetti
Fondazione IRCCS Istituto Neurologico

  1. Nat Commun. 2022 Nov 23. 13(1): 7204
      DddA-derived cytosine base editors (DdCBEs) use programmable DNA-binding TALE repeat arrays, rather than CRISPR proteins, a split double-stranded DNA cytidine deaminase (DddA), and a uracil glycosylase inhibitor to mediate C•G-to-T•A editing in nuclear and organelle DNA. Here we report the development of zinc finger DdCBEs (ZF-DdCBEs) and the improvement of their editing performance through engineering their architectures, defining improved ZF scaffolds, and installing DddA activity-enhancing mutations. We engineer variants with improved DNA specificity by integrating four strategies to reduce off-target editing. We use optimized ZF-DdCBEs to install or correct disease-associated mutations in mitochondria and in the nucleus. Leveraging their small size, we use a single AAV9 to deliver into heart, liver, and skeletal muscle in post-natal mice ZF-DdCBEs that efficiently install disease-associated mutations. While off-target editing of ZF-DdCBEs is likely too high for therapeutic applications, these findings demonstrate a compact, all-protein base editing research tool for precise editing of organelle or nuclear DNA without double-strand DNA breaks.
  2. Prenat Diagn. 2022 Nov 21.
      FBXL4 -associated encephalomyopathic mitochondrial DNA depletion syndrome-13 (MTDPS13) is a rare genetic disorder characterized by early neonatal onset of encephalopathy, seizures, lactic acidosis, hypotonia, dysmorphism, and severe global developmental delay. Prenatal phenotype of molecularly confirmed MTDPS13 has not been well studied. This is the case report of a non-consanguineously conceived fetus ascertained first at 20 weeks of gestation with multiple soft markers. Follow-up fetal ultrasonogram at 26 weeks revealed periventricular cysts, periventricular echogenicity, ventriculomegaly, thin corpus callosum, mega cisterna magna, and large cavum. Fetal MRI confirmed these findings. Postnatally, the baby had clinical and biochemical findings indicative of a mitochondriopathy and died on neonatal day 3. Whole exome sequencing on stored amniotic fluid DNA confirmed the diagnosis of encephalomyopathic mitochondrial DNA depletion syndrome-13 (MTDPS13). This report presents the prenatal phenotype of this rare mitochondriopathy, which has been recognized primarily in postnatal patients. The brain imaging findings in the reported fetus indicate that MTDPS13 is associated with progressive neurological involvement and brain tissue destructive changes starting as early as the second trimester of pregnancy. The case also raises concerns regarding the association of so-called soft markers, which were the only initial finding in this case, with severe monogenic diseases.
  3. Dev Cell. 2022 Nov 21. pii: S1534-5807(22)00760-2. [Epub ahead of print]57(22): 2584-2598.e11
      Autophagy is an essential catabolic process that promotes the clearance of surplus or damaged intracellular components. Loss of autophagy in age-related human pathologies contributes to tissue degeneration through a poorly understood mechanism. Here, we identify an evolutionarily conserved role of autophagy from yeast to humans in the preservation of nicotinamide adenine dinucleotide (NAD) levels, which are critical for cell survival. In respiring mouse fibroblasts with autophagy deficiency, loss of mitochondrial quality control was found to trigger hyperactivation of stress responses mediated by NADases of PARP and Sirtuin families. Uncontrolled depletion of the NAD(H) pool by these enzymes ultimately contributed to mitochondrial membrane depolarization and cell death. Pharmacological and genetic interventions targeting several key elements of this cascade improved the survival of autophagy-deficient yeast, mouse fibroblasts, and human neurons. Our study provides a mechanistic link between autophagy and NAD metabolism and identifies targets for interventions in human diseases associated with autophagic, lysosomal, and mitochondrial dysfunction.
    Keywords:  DNA damage; NAD; PARP; Sirtuins; ageing; autophagy; metabolism; mitochondria; mitophagy
  4. J Neuromuscul Dis. 2022 Nov 16.
      BACKGROUND: Mitochondrial tRNA (MTT) genes are hotspot for mitochondrial DNA mutation and are responsible of half mitochondrial disease. MTT mutations are associated with a broad spectrum of phenotype often with complex multisystem involvement and complex genotype-phenotype correlations. MT-TL1 mutations, among which the m.3243A>G mutation is the most frequent, are associated with myopathy, maternal inherited diabetes and deafness, MELAS, cardiomyopathy, and focal segmental glomerulosclerosis.CASE STUDY: Here we report the case of an Italian 49-years old female presenting with encephalomyopathy, chronic proteinuric kidney disease and a new heteroplasmic m.3274_3275delAC MT-TL1 gene mutation.
    CONCLUSIONS: Our case demonstrates a systemic mitochondrial disease caused by the heteroplasmic m.3274_3275delAC MT-TL1 gene mutation, not yet described in the literature. A mitochondrial disease should be suspected in case of complex multisystem phenotypes, including steroid-resistant nephrotic syndrome with multisystemic involvement.
    Keywords:  glomerulosclerosis; kidney disease; mitochondrial diseases; mitochondrial myopathies; mtDNA
  5. Curr Neurol Neurosci Rep. 2022 Nov 21.
      PURPOSEOF REVIEW: To outline the current landscape of treatments for Leber hereditary optic neuropathy (LHON) along the therapeutic delivery pipeline, exploring the mechanisms of action and evidence for these therapeutic approaches.RECENT FINDINGS: Treatments for LHON can be broadly classified as either mutation-specific or mutation-independent. Mutation-specific therapies aim to correct the underlying mutation through the use of a gene-editing platform or replace the faulty mitochondrial DNA-encoded protein by delivering the wild-type gene using a suitable vector. Recent gene therapy clinical trials assessing the efficacy of allotopically expressed MT-ND4 for the treatment of LHON due to the m.11778G > A mutation in MT-ND4 have shown positive results when treated within 12 months of symptom onset. Mutation-independent therapies can have various downstream targets that aim to improve mitochondrial respiration, reduce mitochondrial stress, inhibit or delay retinal ganglion cell apoptosis, and/or promote retinal ganglion cell survival. Idebenone, a synthetic hydrosoluble analogue of co-enzyme Q10 (ubiquinone), is the only approved treatment for LHON. Mutation-independent approaches to gene therapy under pre-clinical investigation for other neurodegenerative disorders may have the potential to benefit patients with LHON. Although approved treatments are presently limited, innovations in gene therapy and editing are driving the expansion of the therapeutic delivery pipeline for LHON.
    Keywords:  Allotopic expression; Gene therapy; Idebenone; Leber hereditary optic neuropathy; Mitochondrial disease; Optic atrophy
  6. Am J Pathol. 2022 Nov 19. pii: S0002-9440(22)00360-1. [Epub ahead of print]
      Mutations in POLG, the gene encoding the catalytic subunit of DNA polymerase gamma (Polγ), result in clinical syndromes characterized by mitochondrial DNA (mtDNA) depletion in affected tissues with variable organ involvement. The brain is one of the most affected organs, and symptoms include intractable seizures, developmental delay, dementia, and ataxia. Patient-derived induced pluripotent stem cells (iPSCs) provide opportunities to explore mechanisms in affected cell types and potential therapeutic strategies. Fibroblasts from two patients were reprogrammed to create new iPSC models of POLG-related mitochondrial diseases. Compared to control iPSC-derived neurons, mtDNA depletion was observed upon differentiation of the POLG-mutated lines to cortical neurons. POLG-mutated neurons exhibited neurite simplification with decreased mitochondrial content, abnormal mitochondrial structure and function, and increased cell death. Expression of the mitochondrial kinase PTEN-induced kinase 1 (PINK1) mRNA was decreased in patient neurons. Overexpression of PINK1 increased mitochondrial content and ATP:ADP ratios in neurites, decreasing cell death and rescuing neuritic complexity. These data indicate an intersection of Polγ and PINK1 pathways that may offer a novel therapeutic option for patients affected by this spectrum of disorders.
    Keywords:  Alpers-Huttenlocher syndrome; POLG-related disorders; iPSC-derived neurons; mitochondrial disease model; myoclonic epilepsy myopathy sensory ataxia; neuropathology; patient-derived iPSCs
  7. Hum Mol Genet. 2022 Nov 23. pii: ddac287. [Epub ahead of print]
      Mitochondrial involvement in neurodegenerative diseases is widespread and multifactorial. Targeting mitochondrial pathology is therefore of interest. The recent development of bioactive molecules that modulate mitochondrial dynamics (fusion, fission and motility) offers a new therapeutic approach for neurodegenerative diseases with either indirect or direct mitochondrial involvement. Here, we asked: 1. Can enhanced mitochondrial fusion and motility improve secondary mitochondrial pathology in SOD1 mutant amyotrophic lateral sclerosis (ALS)? And: 2. What is the impact of enhancing mitochondria fitness on in vivo manifestations of SOD1 mutant ALS? We observed that small molecule mitofusin activators corrected mitochondrial fragmentation, depolarization and dysmotility in genetically diverse ALS patient reprogrammed motor neurons and fibroblasts, and in motor neurons, sensory neurons and fibroblasts from SOD1 G93A mice. Continuous, but not intermittent, pharmacologic mitofusin activation delayed phenotype progression and lethality in SOD1 G93A mice, reducing neuron loss and improving neuromuscular connectivity. Mechanistically, mitofusin activation increased mitochondrial motility, fitness and residency within neuromuscular synapses, reduced mitochondrial ROS production, and diminished apoptosis in SOD1 mutant neurons. These benefits were accompanied by improved mitochondrial respiratory coupling, despite characteristic SOD1 mutant ALS-associated downregulation of mitochondrial respiratory complexes. Targeting mitochondrial dysdynamism is a promising approach to alleviate pathology caused by secondary mitochondrial dysfunction in some neurodegenerative diseases.
  8. Neuromuscul Disord. 2022 Oct 27. pii: S0960-8966(22)00700-3. [Epub ahead of print]
      Mitochondrial diseases are a heterogeneous group of pathologies, caused by missense mutations, sporadic large-scale deletions of mitochondrial DNA (mtDNA) or mutations of nuclear maintenance genes. We report the case of a patient in whom extended muscle pathology, biochemical and genetic mtDNA analyses have proven to be essential to elucidate a unique asymmetrical myopathic presentation. From the age of 34 years on, the patient has presented with oculomotor disorders, right facial peripheral palsy and predominantly left upper limb muscle weakness and atrophy. By contrast, he displayed no motor weakness on the right hemi-body, and no sensory symptoms, cerebellar syndrome, hypoacusis, or parkinsonism. Cardiac function was normal. CK levels were elevated (671 UI/L). Electroneuromyography (ENMG) and muscle MRI showed diffuse myogenic alterations, more pronounced on the left side muscles. Biopsy of the left deltoid muscle showed multiple mitochondrial defects, whereas in the right deltoid, mitochondrial defects were much less marked. Extended mitochondrial biochemical and molecular workup revealed a unique mtDNA deletion, with a 63.4% heteroplasmy load in the left deltoid, versus 8.1% in the right one. This case demonstrates that, in mitochondrial myopathies, heteroplasmy levels may drastically vary for the same type of muscle, rising the hypothesis of a new pathophysiological mechanism explaining asymmetry in hereditary myopathies.
    Keywords:  Asymmetrical genetic myopathy; Mitochondrial DNA deletion; eKLIPse
  9. Cells. 2022 Nov 14. pii: 3603. [Epub ahead of print]11(22):
      Intercellular mitochondria transfer is a novel form of cell signalling in which whole mitochondria are transferred between cells in order to enhance cellular functions or aid in the degradation of dysfunctional mitochondria. Recent studies have observed intercellular mitochondria transfer between glia and neurons in the brain, and mitochondrial transfer has emerged as a key neuroprotective mechanism in a range of neurological conditions. In particular, artificial mitochondria transfer has sparked widespread interest as a potential therapeutic strategy for brain disorders. In this review, we discuss the mechanisms and effects of intercellular mitochondria transfer in the brain. The role of mitochondrial transfer in neurological conditions, including neurodegenerative disease, brain injury, and neurodevelopmental disorders, is discussed as well as therapeutic strategies targeting mitochondria transfer in the brain.
    Keywords:  brain; glia; mitochondria; neuron
  10. Mitochondrion. 2022 Nov 16. pii: S1567-7249(22)00103-9. [Epub ahead of print]
      Triphenylphosphonium (TPP) derivatives are commonly used to target chemical into mitochondria. We show that alkyl-TPP cause reversible, dose- and hydrophobicity-dependent alterations of mitochondrial morphology and function and a selective decrease of mitochondrial inner membrane proteins including subunits of the respiratory chain complexes, as well as components of the mitochondrial calcium uniporter complex. The treatment with alkyl-TPP resulted in the cleavage of the pro-fusion and cristae organisation regulator Optic atrophy-1. The structural and functional effects of alkyl-TPP were found to be reversible and not merely due to loss of membrane potential. A similar effect was observed with the mitochondria-targeted antioxidant MitoQ.
    Keywords:  MitoQ; inner mitochondrial membrane; lipophilic cations; mitochondria; mitochondrial dynamics; respiratory chain
  11. Brain. 2022 Nov 23. pii: awac444. [Epub ahead of print]
      Pyruvate is an essential metabolite produced by glycolysis in the cytosol and must be transported across the inner mitochondrial membrane (IMM) into the mitochondrial matrix, where it is oxidized to fuel mitochondrial respiration. Pyruvate import is performed by Mitochondrial Pyruvate Carrier (MPC), a hetero-oligomeric complex composed by interdependent subunits MPC1 and MPC2. Pathogenic variants in MPC1 gene disrupt mitochondrial pyruvate uptake and oxidation and cause autosomal-recessive early-onset neurological dysfunction in humans. The present work describes the first pathogenic variants in MPC2 associated with human disease in four patients from two unrelated families. In the first family, patients presented with antenatal developmental abnormalities, harbored a homozygous c.148T > C (p.Trp50Arg) variant. In the second family, patients that presented with infantile encephalopathy carried missense c.2T > G (p.Met1? ) variant disrupting the initiation codon. Patient-derived skin fibroblasts exhibit decreased pyruvate-driven oxygen consumption rates with normal activities of the pyruvate dehydrogenase complex and mitochondrial respiratory chain and no defects in mitochondrial content nor morphology. Re-expression of wild type MPC2 restored pyruvate-dependent respiration rates in patient-derived fibroblasts. The discovery of pathogenic variants in MPC2 therefore broadens the clinical and genetic landscape associated with inborn errors in pyruvate metabolism.
    Keywords:  metabolism; mitochondria; pyruvate carrier
  12. Int J Mol Sci. 2022 Nov 10. pii: 13880. [Epub ahead of print]23(22):
      Mitochondrial oxidative phospho rylation, the center of cellular metabolism, is pivotal for the energy production in eukaryotes. Mitochondrial oxidative phosphorylation relies on the mitochondrial respiratory chain, which consists of four main enzyme complexes and two mobile electron carriers. Mitochondrial enzyme complexes also assemble into respiratory chain supercomplexes (SCs) through specific interactions. The SCs not only have respiratory functions but also improve the efficiency of electron transfer and reduce the production of reactive oxygen species (ROS). Impaired assembly of SCs is closely related to various diseases, especially neurodegenerative diseases. Therefore, SCs play important roles in improving the efficiency of the mitochondrial respiratory chain, as well as maintaining the homeostasis of cellular metabolism. Here, we review the structure, assembly, and functions of SCs, as well as the relationship between mitochondrial SCs and diseases.
    Keywords:  assembly; cytochrome c; mitochondria; respiratory chain; supercomplexes
  13. Mol Ther Nucleic Acids. 2022 Dec 13. 30 359-377
      Mitochondrial diseases are one of the largest groups of neurological genetic disorders. Despite continuous efforts of the scientific community, no cure has been developed, and most treatment strategies rely on managing the symptoms. After the success of coronavirus disease 2019 (COVID-19) mRNA vaccines and accelerated US Food and Drug Administration (FDA) approval of four new RNAi drugs, we sought to investigate the potential of mitochondrion-targeting RNA-based therapeutic agents for treatment of mitochondrial diseases. Here we describe the causes and existing therapies for mitochondrial diseases. We then detail potential RNA-based therapeutic strategies for treatment of mitochondrial diseases, including use of antisense oligonucleotides (ASOs) and RNAi drugs, allotopic therapies, and RNA-based antigenomic therapies that aim to decrease the level of deleterious heteroplasmy in affected tissues. Finally, we review different mechanisms by which RNA-based therapeutic agents can be delivered to the mitochondrial matrix, including mitochondrion-targeted nanocarriers and endogenous mitochondrial RNA import pathways.
    Keywords:  MT: Oligonucleotides, Therapies and Applications; RNA therapeutics; RNA therapy; mitochondrial DNA; mitochondrial RNA import; mitochondrial disease; mitochondrial therapy; mitochondrion-targeted nanocarrier
  14. J Biosci. 2022 ;pii: 67. [Epub ahead of print]47
      Eukaryotic cells contain multiple copies of mitochondrial DNA (mtDNA) in discrete organelles or as tubular networks throughout the cytoplasm. The mtDNA copy number is dynamically regulated by mitochondrial biogenesis and mitophagy processes. However, the conditions regulating mtDNA replication, an essential component of biogenesis, are unknown. We observed that short-term (2 h) treatment of rat myoblasts with oligomycin, a specific inhibitor of the mitochondrial F1F0 ATP synthase, resulted in stimulation of mtDNA synthesis from the OH replication origin. This effect was abrogated by Compound C, an antagonist of the AMP-dependent protein kinase (AMPK), a universal intracellular energy sensor, and in AMPK-knockdown cells, indicating that mtDNA replication is regulated by AMPK under oxidative phosphorylation (OXPHOS)- deficient conditions. Using antibody decoration, enzymatically active AMPK, phosphorylated at T172 of the α1 subunit, was found to be located on the mitochondrial surface. Furthermore, oligomycin induced the compartmentalization of several mRNAs encoding OXPHOS components and mtDNA replication factors to mitochondria. Compartmentalization of mRNAs was inhibited by Compound C. We infer that AMPK is locally activated by inhibition of the F1F0 ATP synthase to stimulate association of mtDNA replication factor mRNAs, leading to stimulation of mtDNA synthesis. The findings have implications for the clonal expansion of OXPHOS-deficient mtDNA mutant mitochondria in human patients, with clinical consequences.
  15. PLoS One. 2022 ;17(11): e0269649
      INTRODUCTION: Drug development for neurodegenerative diseases such as Friedreich's ataxia (FRDA) is limited by a lack of validated, sensitive biomarkers of pharmacodynamic response in affected tissue and disease progression. Studies employing neuroimaging measures to track FRDA have thus far been limited by their small sample sizes and limited follow up. TRACK-FA, a longitudinal, multi-site, and multi-modal neuroimaging natural history study, aims to address these shortcomings by enabling better understanding of underlying pathology and identifying sensitive, clinical trial ready, neuroimaging biomarkers for FRDA.METHODS: 200 individuals with FRDA and 104 control participants will be recruited across seven international study sites. Inclusion criteria for participants with genetically confirmed FRDA involves, age of disease onset ≤ 25 years, Friedreich's Ataxia Rating Scale (FARS) functional staging score of ≤ 5, and a total modified FARS (mFARS) score of ≤ 65 upon enrolment. The control cohort is matched to the FRDA cohort for age, sex, handedness, and years of education. Participants will be evaluated at three study visits over two years. Each visit comprises of a harmonized multimodal Magnetic Resonance Imaging (MRI) and Spectroscopy (MRS) scan of the brain and spinal cord; clinical, cognitive, mood and speech assessments and collection of a blood sample. Primary outcome measures, informed by previous neuroimaging studies, include measures of: spinal cord and brain morphometry, spinal cord and brain microstructure (measured using diffusion MRI), brain iron accumulation (using Quantitative Susceptibility Mapping) and spinal cord biochemistry (using MRS). Secondary and exploratory outcome measures include clinical, cognitive assessments and blood biomarkers.
    DISCUSSION: Prioritising immediate areas of need, TRACK-FA aims to deliver a set of sensitive, clinical trial-ready neuroimaging biomarkers to accelerate drug discovery efforts and better understand disease trajectory. Once validated, these potential pharmacodynamic biomarkers can be used to measure the efficacy of new therapeutics in forestalling disease progression.
  16. Front Endocrinol (Lausanne). 2022 ;13 1059085
      Bidirectional crosstalk between the nuclear and mitochondrial genomes is essential for proper cell functioning. Mitochondrial DNA copy number (mtDNA-CN) and heteroplasmy influence mitochondrial function, which can influence the nuclear genome and contribute to health and disease. Evidence shows that mtDNA-CN and heteroplasmic variation are associated with aging, complex disease, and all-cause mortality. Further, the nuclear epigenome may mediate the effects of mtDNA variation on disease. In this way, mitochondria act as an environmental biosensor translating vital information about the state of the cell to the nuclear genome. Cellular communication between mtDNA variation and the nuclear epigenome can be achieved by modification of metabolites and intermediates of the citric acid cycle and oxidative phosphorylation. These essential molecules (e.g. ATP, acetyl-CoA, ɑ-ketoglutarate and S-adenosylmethionine) act as substrates and cofactors for enzymes involved in epigenetic modifications. The role of mitochondria as an environmental biosensor is emerging as a critical modifier of disease states. Uncovering the mechanisms of these dynamics in disease processes is expected to lead to earlier and improved treatment for a variety of diseases. However, the influence of mtDNA-CN and heteroplasmy variation on mitochondrially-derived epigenome-modifying metabolites and intermediates is poorly understood. This perspective will focus on the relationship between mtDNA-CN, heteroplasmy, and epigenome modifying cofactors and substrates, and the influence of their dynamics on the nuclear epigenome in health and disease.
    Keywords:  DNA methylation; aging; disease; epigenome; histone acetylation; metabolism; mitochondrial DNA
  17. Mol Genet Metab Rep. 2022 Dec;33 100931
      Malate dehydrogenases (MDH) serve a critical role in maintaining equilibrium of the NAD+/NADH ratio between the mitochondria and cytosol through the catalysis of the oxidation of L-malate to oxaloacetate in a reversible, NADH-dependent manner. MDH2 encodes the mitochondrial isoform, which is integral to the tricarboxylic acid cycle and thus energy homeostasis. Recently, five patients harboring compound heterozygous MDH2 variants have been described, three with early-onset epileptic encephalopathy, one with a stroke-like episode, and one with dilated cardiomyopathy. Here, we describe an additional seven patients with biallelic variants in MDH2, the largest and most neurodevelopmentally and ethnically diverse cohort to-date, including homozygous variants, a sibling pair, non-European patients, and an adult. From these patients, we learn that MDH2 deficiency results in a biochemical signature including elevations of plasma lactate and the lactate:pyruvate ratio with urinary excretion of malate. It also results in a recognizable constellation of neuroimaging findings of anterior-predominant cerebral atrophy, subependymal cysts with ventricular septations. We also recognize MDH2 deficiency as a cause of Leigh syndrome. Taken with existing patient reports, we conclude that MDH2 deficiency is an emerging and likely under-recognized cause of infantile epileptic encephalopathy and provide a framework for medical evaluation of patients identified with biallelic MDH2 variants.
    Keywords:  Epileptic encephalopathy; Leigh syndrome; MDH2; Malate dehydrogenase; Mitochondrial malate dehydrogenase; TCA cycle
  18. J Clin Med. 2022 Nov 14. pii: 6742. [Epub ahead of print]11(22):
      Alzheimer's disease (AD), a chronic and progressive neurodegenerative disease, is characterized by memory and cognitive impairment and by the accumulation in the brain of abnormal proteins, more precisely beta-amyloid (β-amyloid or Aβ) and Tau proteins. Studies aimed at researching pharmacological treatments against AD have focused precisely on molecules capable, in one way or another, of preventing/eliminating the accumulations of the aforementioned proteins. Unfortunately, more than 100 years after the discovery of the disease, there is still no effective therapy in modifying the biology behind AD and nipping the disease in the bud. This state of affairs has made neuroscientists suspicious, so much so that for several years the idea has gained ground that AD is not a direct neuropathological consequence taking place downstream of the deposition of the two toxic proteins, but rather a multifactorial disease, including mitochondrial dysfunction as an early event in the pathogenesis of AD, occurring even before clinical symptoms. This is the reason why the search for pharmacological agents capable of normalizing the functioning of these subcellular organelles of vital importance for nerve cells is certainly to be considered a promising approach to the design of effective neuroprotective drugs aimed at preserving this organelle to arrest or delay the progression of the disease. Here, our intent is to provide an updated overview of the mitochondrial alterations related to this disorder and of the therapeutic strategies (both natural and synthetic) targeting mitochondrial dysfunction.
    Keywords:  Alzheimer; mitochondrial bioenergetics; mitochondrial biogenesis; mitochondrial dynamics; mitochondrial dysfunction; mitophagy; neurodegeneration; therapeutic strategies
  19. Elife. 2022 Nov 21. pii: e65488. [Epub ahead of print]11
      The clinical and largely unpredictable heterogeneity of phenotypes in patients with mitochondrial disorders demonstrates the ongoing challenges in the understanding of this semi-autonomous organelle in biology and disease. Previously, we used the gene-breaking transposon to create 1200 transgenic zebrafish strains tagging protein-coding genes (1), including the lrpprc locus. Here we present and characterize a new genetic revertible animal model that recapitulates components of Leigh Syndrome French Canadian Type (LSFC), a mitochondrial disorder that includes diagnostic liver dysfunction. LSFC is caused by allelic variations in the LRPPRC gene, involved in mitochondrial mRNA polyadenylation and translation. lrpprc zebrafish homozygous mutants displayed biochemical and mitochondrial phenotypes similar to clinical manifestations observed in patients, including dysfunction in lipid homeostasis. We were able to rescue these phenotypes in the disease model using a liver-specific genetic model therapy, functionally demonstrating a previously under-recognized critical role for the liver in the pathophysiology of this disease.
    Keywords:  developmental biology; genetics; genomics; zebrafish
  20. Hum Mol Genet. 2022 Nov 26. pii: ddac292. [Epub ahead of print]
      The mitochondrial DNA mutation m.9032 T > C was previously identified in patients presenting with NARP (Neuropathy Ataxia Retinitis Pigmentosa). Their clinical features had a maternal transmission and patient's cells showed a reduced oxidative phosphorylation capacity, elevated reactive oxygen species (ROS) production and hyperpolarization of the mitochondrial inner membrane, providing evidence that m.9032 T > C is truly pathogenic. This mutation leads to replacement of a highly conserved leucine residue with proline at position 169 of ATP synthase subunit a (L169P). This protein and a ring of identical c-subunits (c-ring) move protons through the mitochondrial inner membrane coupled to ATP synthesis. We herein investigated the consequences of m.9032 T > C on ATP synthase in a strain of Saccharomyces cerevisiae with an equivalent mutation (L186P). The mutant enzyme assembled correctly but was mostly inactive as evidenced by a > 95% drop in the rate of mitochondrial ATP synthesis and absence of significant ATP-driven proton pumping across the mitochondrial membrane. Intragenic suppressors selected from L186P yeast restoring ATP synthase function to varying degrees (30-70%) were identified at the original mutation site (L186S) or in another position of the subunit a (H114Q, I118T). In light of atomic structures of yeast ATP synthase recently described, we conclude from these results that m.9032 T > C disrupts proton conduction between the external side of the membrane and the c-ring, and that H114Q and I118T enable protons to access the c-ring through a modified pathway.
    Keywords:  mitochondrial diseasesNARP syndromemitochondrial DNAATP synthase subunit ayeastsuppressor genetics
  21. Clin Biochem. 2022 Nov 17. pii: S0009-9120(22)00244-2. [Epub ahead of print]
    Keywords:  Heteroplasmy; MELAS; Mitochondrial DNA; Phenotype; m.3243A>G
  22. Drugs Today (Barc). 2022 11;58(11): 547-552
      Dominant optic atrophy (DOA) is caused by OPA1 gene mutation, and it represents one of the most frequently diagnosed forms of hereditary optic neuropathies. This neurodegenerative disorder typically occurs in the first decades of life, and it is often associated with severe visual impairment. For this reason, several treatment options have been examined for the management of DOA, including vitamin supplements, ubiquinone analogues (in particular idebenone) and, more recently, gene therapy. Among them, idebenone has shown the most promising clinical outcomes in recent real-life studies. Furthermore, gene therapy represents also a promising therapeutic approach; however, more evidence in clinical trials is needed. In this review, we will summarize and discuss all the possible treatment options for DOA, in order to identify the current optimal management in these patients, whose visual prognosis remains unfortunately poor and unsatisfactory in the everyday clinical practice.
    Keywords:  Dominant optic atrophy; Eye disorders; Hereditary optic neuropathies; Leber hereditary optic neuropathy; Ubiquinone analogues
  23. Antioxidants (Basel). 2022 Nov 19. pii: 2293. [Epub ahead of print]11(11):
      In this article we have reviewed the potential role of coenzyme Q10 (CoQ10) in the pathogenesis and treatment of a number of less common age-related disorders, for many of which effective therapies are not currently available. For most of these disorders, mitochondrial dysfunction, oxidative stress and inflammation have been implicated in the disease process, providing a rationale for the potential therapeutic use of CoQ10, because of its key roles in mitochondrial function, as an antioxidant, and as an anti-inflammatory agent. Disorders reviewed in the article include multi system atrophy, progressive supranuclear palsy, sporadic adult onset ataxia, and pulmonary fibrosis, together with late onset versions of Huntington's disease, Alexander disease, lupus, anti-phospholipid syndrome, lysosomal storage disorders, fibromyalgia, Machado-Joseph disease, acyl-CoA dehydrogenase deficiency, and Leber's optic neuropathy.
    Keywords:  age related disorders; coenzyme Q10; late onset disorders; multiple system atrophy; progressive supranuclear palsy; sporadic adult onset ataxia
  24. Biochim Biophys Acta Bioenerg. 2022 Nov 17. pii: S0005-2728(22)00403-0. [Epub ahead of print]1864(2): 148933
    Keywords:  Cell respiration; Heme‑copper oxidases; Oxygen reduction; Respiratory chain
  25. Stem Cell Res. 2022 Nov 14. pii: S1873-5061(22)00320-8. [Epub ahead of print]65 102971
      Human dermal fibroblasts from a Leigh Syndrome (LS) patient harboring the heterozygous NDUFS1 R557X/D618N compound mutation were reprogrammed to generate integration-free induced pluripotent stem cells (iPSCs). The full characterization of IUFi002-A-iPSCs demonstrated that the line is free of exogenous reprogramming genes and maintains the genomic integrity. IUFi002-A-iPSCs' pluripotency was confirmed by the expression of pluripotency markers and embryoid body-based differentiation into cell types representative of each of the three germ layers. The generated iPSC line provides a powerful tool to investigate LS and analyze the molecular mechanisms underlying NDUFS1 mutations-induced pathology.
  26. J Vet Intern Med. 2022 Nov 25.
      BACKGROUND: In Belgian Malinois, a KCNJ10 variant causes progressive spinocerebellar degeneration.HYPOTHESIS/OBJECTIVES: Describe the clinical, diagnostic, pathological and genetic features of spinocerebellar degeneration in the Bouvier des Ardennes breed.
    ANIMALS: Five affected Bouvier des Ardennes puppies with spinocerebellar ataxia (SCA), 8 healthy related dogs, and 63 healthy unrelated Bouvier des Ardennes.
    METHODS: Sequential case study.
    RESULTS: Clinical signs started at 6 weeks of age in 1 puppy with severe signs of cerebellar disease, and at 7 to 10 weeks of age in the 4 remaining puppies with milder signs of spinocerebellar disease. The first puppy displayed severe intention tremors and rapidly progressive generalized hypermetric ataxia, whereas the 4 others developed a milder progressive SCA. Euthanasia after progression to nonambulatory status was performed by 8 weeks of age in the first puppy, and before 11 months of age in the 4 remaining puppies. Histopathology revealed cerebellar spongy degeneration and a focal symmetrical demyelinating myelopathy. All cases were homozygous for KCNJ10 XM_545752.6:c.986T>C(p.(Leu329Pro)), which is pathogenic for SCA with (or without) myokymia, seizures or both (SAMS) and spongy degeneration and cerebellar ataxia (SDCA) 1 in Belgian Malinois dogs. All sampled parents were heterozygous and none of the healthy dogs were homozygous for this recessive variant. This variant has an allele frequency of 15% in the 63 healthy dogs studied.
    CONCLUSIONS AND CLINICAL IMPORTANCE: Inherited spinocerebellar degeneration also affects the Bouvier des Ardennes breed and is caused by a KCNJ10 variant. It can present with a spectrum of severity grades, ranging from severe cerebellar to milder spinocerebellar signs.
    Keywords:  SAMS; SDCA; demyelinating myelopathy; hypermetric ataxia; intention tremors; spongy degeneration
  27. Int J Mol Sci. 2022 Nov 21. pii: 14482. [Epub ahead of print]23(22):
      Aicardi-Goutières syndrome (AGS) is a rare encephalopathy characterized by neurological and immunological features. Mitochondrial dysfunctions may lead to mitochondrial DNA (mtDNA) release and consequent immune system activation. We investigated the role of mitochondria and mtDNA in AGS pathogenesis by studying patients mutated in RNASEH2B and RNASEH2A genes. Lymphoblastoid cell lines (LCLs) from RNASEH2A- and RNASEH2B-mutated patients and healthy control were used. Transmission Electron Microscopy (TEM) and flow cytometry were used to assess morphological alterations, reactive oxygen species (ROS) production and mitochondrial membrane potential variations. Seahorse Analyzer was used to investigate metabolic alterations, and mtDNA oxidation and VDAC1 oligomerization were assessed by immunofluorescence. Western blot and RT-qPCR were used to quantify mtTFA protein and mtDNA release. Morphological alterations of mitochondria were observed in both mutated LCLs, and loss of physiological membrane potential was mainly identified in RNASEH2A LCLs. ROS production and 8-oxoGuanine levels were increased in RNASEH2B LCLs. Additionally, the VDAC1 signal was increased, suggesting a mitochondrial pore formation possibly determining mtDNA release. Indeed, higher cytoplasmic mtDNA levels were found in RNASEH2B LCLs. Metabolic alterations confirmed mitochondrial damage in both LCLs. Data highlighted mitochondrial alterations in AGS patients' LCLs suggesting a pivotal role in AGS pathogenesis.
    Keywords:  Aicardi–Goutières syndrome; IFN-α; ROS; autoimmune diseases; inflammation; mitochondrial disorder; mitochondrial stress; mtDNA
  28. Int J Mol Sci. 2022 Nov 08. pii: 13703. [Epub ahead of print]23(22):
      Myostatin (Mstn) is a major negative regulator of skeletal muscle mass and initiates multiple metabolic changes. The deletion of the Mstn gene in mice leads to reduced mitochondrial functions. However, the underlying regulatory mechanisms remain unclear. In this study, we used CRISPR/Cas9 to generate myostatin-knockout (Mstn-KO) mice via pronuclear microinjection. Mstn-KO mice exhibited significantly larger skeletal muscles. Meanwhile, Mstn knockout regulated the organ weights of mice. Moreover, we found that Mstn knockout reduced the basal metabolic rate, muscle adenosine triphosphate (ATP) synthesis, activities of mitochondrial respiration chain complexes, tricarboxylic acid cycle (TCA) cycle, and thermogenesis. Mechanistically, expressions of silent information regulator 1 (SIRT1) and phosphorylated adenosine monophosphate-activated protein kinase (pAMPK) were down-regulated, while peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α) acetylation modification increased in the Mstn-KO mice. Skeletal muscle cells from Mstn-KO and WT were treated with AMPK activator 5-aminoimidazole-4-carboxamide riboside (AICAR), and the AMPK inhibitor Compound C, respectively. Compared with the wild-type (WT) group, Compound C treatment further down-regulated the expression or activity of pAMPK, SIRT1, citrate synthase (CS), isocitrate dehydrogenase (ICDHm), and α-ketoglutarate acid dehydrogenase (α-KGDH) in Mstn-KO mice, while Mstn knockout inhibited the AICAR activation effect. Therefore, Mstn knockout affects mitochondrial function by inhibiting the AMPK/SIRT1/PGC1α signaling pathway. The present study reveals a new mechanism for Mstn knockout in regulating energy homeostasis.
    Keywords:  AMPK/SIRT1/PGC-1α; CRISPR/Cas9; knockout; mitochondrial; myostatin; skeletal muscle
  29. Antioxidants (Basel). 2022 Nov 15. pii: 2250. [Epub ahead of print]11(11):
      Diabetic Retinopathy (DR) is one of the most important microvascular complications of diabetes mellitus, which can lead to blindness in severe cases. Mitochondria are energy-producing organelles in eukaryotic cells, which participate in metabolism and signal transduction, and regulate cell growth, differentiation, aging, and death. Metabolic changes of retinal cells and epigenetic changes of mitochondria-related genes under high glucose can lead to mitochondrial dysfunction and induce mitochondrial pathway apoptosis. In addition, mitophagy and mitochondrial dynamics also change adaptively. These mechanisms may be related to the occurrence and progression of DR, and also provide valuable clues for the prevention and treatment of DR. This article reviews the mechanism of DR induced by mitochondrial dysfunction, and the prospects for related treatment.
    Keywords:  apoptosis; diabetic retinopathy; epigenetics; metabolism; mitochondrial; mitophagy
  30. Front Genet. 2022 ;13 953762
      Autism spectrum disorder (ASD) is a clinically heterogeneous class of neurodevelopmental conditions with a strong, albeit complex, genetic basis. The genetic architecture of ASD includes different genetic models, from monogenic transmission at one end, to polygenic risk given by thousands of common variants with small effects at the other end. The mitochondrial DNA (mtDNA) was also proposed as a genetic modifier for ASD, mostly focusing on maternal mtDNA, since the paternal mitogenome is not transmitted to offspring. We extensively studied the potential contribution of mtDNA in ASD pathogenesis and risk through deep next generation sequencing and quantitative PCR in a cohort of 98 families. While the maternally-inherited mtDNA did not seem to predispose to ASD, neither for haplogroups nor for the presence of pathogenic mutations, an unexpected influence of paternal mtDNA, apparently centered on haplogroup U, came from the Italian families extrapolated from the test cohort (n = 74) when compared to the control population. However, this result was not replicated in an independent Italian cohort of 127 families and it is likely due to the elevated paternal age at time of conception. In addition, ASD probands showed a reduced mtDNA content when compared to their unaffected siblings. Multivariable regression analyses indicated that variants with 15%-5% heteroplasmy in probands are associated to a greater severity of ASD based on ADOS-2 criteria, whereas paternal super-haplogroups H and JT were associated with milder phenotypes. In conclusion, our results suggest that the mtDNA impacts on ASD, significantly modifying the phenotypic expression in the Italian population. The unexpected finding of protection induced by paternal mitogenome in term of severity may derive from a role of mtDNA in influencing the accumulation of nuclear de novo mutations or epigenetic alterations in fathers' germinal cells, affecting the neurodevelopment in the offspring. This result remains preliminary and needs further confirmation in independent cohorts of larger size. If confirmed, it potentially opens a different perspective on how paternal non-inherited mtDNA may predispose or modulate other complex diseases.
    Keywords:  autism risk; autism spectrum disorder; mitochondrial DNA; mitochondrial haplogroups; universal heteroplasmy
  31. Ann Afr Med. 2022 Oct-Dec;21(4):21(4): 426-431
      Background: Leigh syndrome (LS) is a progressive neurodegenerative disorder of infancy/early childhood secondary to mitochondrial dysfunction. Imaging plays a pivotal role in the diagnosis of LS with certain typical magnetic resonance imaging (MRI) findings considered as a part of diagnostic criteria. We appraised various MRI findings on conventional MRI sequences and also assessed potential correlation between diffusion abnormalities and patient's clinical presentation.Aims: Our aim was to describe various patterns of central nervous system involvement in LS and to assess the correlation of diffusion-weighted imaging abnormalities with clinical presentation.
    Settings and Design: The design of the study was retrospective comprising 8 children with LS who had MRI between years 2014 and 2019.
    Subjects and Methods: Eight children between the age group of 4 months 8 years with LS based on clinical presentation, elevated lactate levels in CSF/Blood, and typical MRI findings were included in the study.
    Results and Conclusions: Brainstem was involved all (100%) patients while basal ganglia was affected in 5 (62.5%) children. Cerebral white matter involvement was present in 3 (37.5%) children, cerebellar in 2 (25%) children while spinal, corpus callosum, and thalamic involvement were observed in one (12.5%) patient each. Diffusion restriction was observed in 6 children, all of them presented with altered sensorium. Conventional MRI serves as an excellent tool for the diagnosis of LS in children with clinical suspicion. Acute encephalopathy frequently presents with diffusion restriction corresponding to active lesions. Hence, diffusion restriction on MRI predicts the activity of lesions in patients with LS.
    Keywords:  Basal ganglia; brainstem; diffusion-weighted imaging; hypotonia; serum lactate
  32. Sci Rep. 2022 Nov 19. 12(1): 19948
      Severe malnutrition accounts for half-a-million deaths annually in children under the age of five. Despite improved WHO guidelines, inpatient mortality remains high and is associated with metabolic dysfunction. Previous studies suggest a correlation between hepatic metabolic dysfunction and impaired autophagy. We aimed to determine the role of mTORC1 inhibition in a murine model of malnutrition-induced hepatic dysfunction. Wild type weanling C57/B6 mice were fed a 18 or 1% protein diet for two weeks. A third low-protein group received daily rapamycin injections, an mTORC1 inhibitor. Hepatic metabolic function was assessed by histology, immunofluorescence, gene expression, metabolomics and protein levels. Low protein-fed mice manifested characteristics of severe malnutrition, including weight loss, hypoalbuminemia, hypoglycemia, hepatic steatosis and cholestasis. Low protein-fed mice had fewer mitochondria and showed signs of impaired mitochondrial function. Rapamycin prevented hepatic steatosis, restored ATP levels and fasted plasma glucose levels compared to untreated mice. This correlated with increased content of LC3-II, and decreased content mitochondrial damage marker, PINK1. We demonstrate that hepatic steatosis and disturbed mitochondrial function in a murine model of severe malnutrition can be partially prevented through inhibition of mTORC1. These findings suggest that stimulation of autophagy could be a novel approach to improve metabolic function in severely malnourished children.
  33. Curr Gene Ther. 2022 Nov 18.
      Duchenne and Becker muscular dystrophies are allelic X-linked recessive neuromuscular diseases affecting both skeletal and cardiac muscles. Therefore, owing to their single X chromosome, the affected boys receive the pathogenic gene mutations from their unknowing carrier mothers. Current pharmacological drugs are palliative that address the symptoms of the disease rather than the genetic cause imbedded in the Dystrophin gene DNA sequence. Therefore, alternative therapies like gene drugs that can address the genetic cause of the disease at its root is crucial, which include gene transfer/implantation, exon skipping, and gene editing. Presently, it is possible through genetic reprogramming to engineer AAV vectors to deliver certain therapeutic cargos specifically to muscle or other organs regardless of their serotype. Similarly, it is possible to direct the biogenesis of exosomes to carry gene editing constituents or certain therapeutic cargos to specific tissue or cell type like brain and muscle. While autologous exosomes are immunologically inert, it is possible to camouflage AAV capsids, gold and lipid nanoparticles to evade the immune system recognition. In this review, we highlight current opportunities for Duchenne muscular dystrophy gene therapy, which has been known thus far as an incurable genetic disease. This article is a part of Gene Therapy of Rare Genetic Diseases thematic issue.
    Keywords:  Adeno-associated virus; CRISPR/Cas gene editing; Duchene muscular dystrophy; Exon skipping; Gene drugs; Gene therapy; Genetic drugs; Genomic drugs.; Microdystrophin; Pharmacophore
  34. Front Mol Neurosci. 2022 ;15 1042616
      Neurons in the brain have a uniquely polarized structure consisting of multiple dendrites and a single axon generated from a cell body. Interestingly, intracellular mitochondria also show strikingly polarized morphologies along the dendrites and axons: in cortical pyramidal neurons (PNs), dendritic mitochondria have a long and tubular shape, while axonal mitochondria are small and circular. Mitochondria play important roles in each compartment of the neuron by generating adenosine triphosphate (ATP) and buffering calcium, thereby affecting synaptic transmission and neuronal development. In addition, mitochondrial shape, and thereby function, is dynamically altered by environmental stressors such as oxidative stress or in various neurodegenerative diseases including Alzheimer's disease and Parkinson's disease. Although the importance of altered mitochondrial shape has been claimed by multiple studies, methods for studying this stress-sensitive organelle have not been standardized. Here we address pertinent steps that influence mitochondrial morphology during experimental processes. We demonstrate that fixative solutions containing only paraformaldehyde (PFA), or that introduce hypoxic conditions during the procedure, induce dramatic fragmentation of mitochondria both in vitro and in vivo. This disruption was not observed following the use of glutaraldehyde (GA) addition or oxygen supplementation, respectively. Finally, using pre-formed fibril α-synuclein treated neurons, we show fixative choice can alter experimental outcomes. Specifically, α-synuclein-induced mitochondrial remodeling could not be observed with PFA only fixation as fixation itself caused mitochondrial fragmentation. Our study provides optimized methods for examining mitochondrial morphology in neurons and demonstrates that fixation conditions are critical when investigating the underlying cellular mechanisms involving mitochondria in physiological and neurodegenerative disease models.
    Keywords:  fixation; hypoxia; mitochondria; neuron; perfusion
  35. Nat Commun. 2022 Nov 25. 13(1): 7252
      Formation of branched organs requires sequential differentiation of stem cells. In this work, we find that the conducting airways derived from SOX2+ progenitors in the murine lungs fail to form without mTOR complex 1 (mTORC1) signaling and are replaced by lung cysts. Proximal-distal patterning through transitioning of distal SOX9+ progenitors to proximal SOX2+ cells is disrupted. Mitochondria number and ATP production are reduced. Compromised mitochondrial capacity results in a similar defect as that in mTORC1-deficient lungs. This suggests that mTORC1 promotes differentiation of SOX9+ progenitors to form the conducting airways by modulating mitochondrial capacity. Surprisingly, in all mutants, saccules are produced from lung cysts at the proper developmental time despite defective branching. SOX9+ progenitors also differentiate into alveolar epithelial type I and type II cells within saccules. These findings highlight selective utilization of energy and regulatory programs during stem cell differentiation to produce distinct structures of the mammalian lungs.
  36. EMBO Rep. 2022 Nov 23. e54006
      While previous studies have identified cancer stem-like cells (CSCs) as a crucial driver for chemoresistance and tumor recurrence, the underlying mechanisms for populating the CSC pool remain unclear. Here, we identify hypermitophagy as a feature of human lung CSCs, promoting metabolic adaption via the Notch1-AMPK axis to drive CSC expansion. Specifically, mitophagy is highly active in CSCs, resulting in increased mitochondrial DNA (mtDNA) content in the lysosome. Lysosomal mtDNA acts as an endogenous ligand for Toll-like receptor 9 (TLR9) that promotes Notch1 activity. Notch1 interacts with AMPK to drive lysosomal AMPK activation by inducing metabolic stress and LKB1 phosphorylation. This TLR9-Notch1-AMPK axis supports mitochondrial metabolism to fuel CSC expansion. In patient-derived xenograft chimeras, targeting mitophagy and TLR9-dependent Notch1-AMPK pathway restricts tumor growth and CSC expansion. Taken together, mitochondrial hemostasis is interlinked with innate immune sensing and Notch1-AMPK activity to increase the CSC pool of human lung cancer.
    Keywords:  AMPK; Notch1; TLR9; cancer stem-like cell; mitophagy
  37. Nat Commun. 2022 Nov 24. 13(1): 7215
      Tumour cell metabolic plasticity is essential for tumour progression and therapeutic responses, yet the underlying mechanisms remain poorly understood. Here, we identify Prospero-related homeobox 1 (PROX1) as a crucial factor for tumour metabolic plasticity. Notably, PROX1 is reduced by glucose starvation or AMP-activated protein kinase (AMPK) activation and is elevated in liver kinase B1 (LKB1)-deficient tumours. Furthermore, the Ser79 phosphorylation of PROX1 by AMPK enhances the recruitment of CUL4-DDB1 ubiquitin ligase to promote PROX1 degradation. Downregulation of PROX1 activates branched-chain amino acids (BCAA) degradation through mediating epigenetic modifications and inhibits mammalian target-of-rapamycin (mTOR) signalling. Importantly, PROX1 deficiency or Ser79 phosphorylation in liver tumour shows therapeutic resistance to metformin. Clinically, the AMPK-PROX1 axis in human cancers is important for patient clinical outcomes. Collectively, our results demonstrate that deficiency of the LKB1-AMPK axis in cancers reactivates PROX1 to sustain intracellular BCAA pools, resulting in enhanced mTOR signalling, and facilitating tumourigenesis and aggressiveness.
  38. Int J Mol Sci. 2022 Nov 18. pii: 14286. [Epub ahead of print]23(22):
      Amino acids are crucial nutrients involved in several cellular and physiological processes, including fertilization and early embryo development. In particular, Leucine and Arginine have been shown to stimulate implantation, as lack of both in a blastocyst culture system is able to induce a dormant state in embryos. The aim of this work was to evaluate the effects of Leucine and Arginine withdrawal on pluripotent mouse embryonic stem cell status, notably, their growth, self-renewal, as well as glycolytic and oxidative metabolism. Our results show that the absence of both Leucine and Arginine does not affect mouse embryonic stem cell pluripotency, while reducing cell proliferation through cell-cycle arrest. Importantly, these effects are not related to Leukemia Inhibitory Factor (LIF) and are reversible when both amino acids are reconstituted in the culture media. Moreover, a lack of these amino acids is related to a reduction in glycolytic and oxidative metabolism and decreased protein translation in mouse embryonic stem cells (mESCs), while maintaining their pluripotent status.
    Keywords:  Arginine; Leucine; mESC
  39. Mol Ther. 2022 Nov 24. pii: S1525-0016(22)00670-0. [Epub ahead of print]
      Limb-girdle muscular dystrophy type R25 (LGMDR25) is caused by recessive mutations in BVES encoding a cAMP binding protein, characterized by progressive muscular dystrophy with deteriorating muscle function and impaired cardiac conduction in patients. There is currently no therapeutic treatment for LGMDR25 patients. Here we report the efficacy and safety of recombinant adeno-associated virus 9 (AAV9)-mediated systemic delivery of human BVES driven by a muscle-specific promoter MHCK7 (AAV9.BVES) in BVES-knockout (BVES-KO) mice. AAV9.BVES efficiently transduced the cardiac and skeletal muscle tissues when intraperitoneally injected into neonatal BVES-KO mice. AAV9.BVES dramatically improved body weight gain, muscle mass, muscle strength and exercise performance in BVES-KO mice regardless of sex. AAV9.BVES also significantly ameliorated the histopathological features of muscular dystrophy. The heart rate reduction was also normalized in BVES-KO mice under exercise-induced stress following systemic AAV9.BVES delivery. Moreover, intravenous AAV9.BVES administration into adult BVES-KO mice after the disease onset also resulted in substantial improvement in body weight, muscle mass, muscle contractility, and stress-induced heart rhythm abnormality. No obvious toxicity was detected. Taken together, these results provide the proof-of-concept evidence to support the AAV9.BVES gene therapy for LGMDR25.
  40. Bioorg Med Chem Lett. 2022 Nov 19. pii: S0960-894X(22)00558-3. [Epub ahead of print] 129082
      Spinocerebellar ataxia type 31 is an autosomal dominant neurodegenerative disease caused by aberrant insertion of d(TGGAA)n into the intron shared by brain expressed, associated with Nedd4 and thymidine kinase 2 genes in chromosome 16. We reported that a naphthyridine dimer derivative with amidated linker structure (ND-amide) bound to GGA/GGA motifs in hairpin structures of d(TGGAA)n. The binding of naphthyridine dimer derivatives to the GGA/GGA motif was sensitive to the linker structures. The amidation of the linker in naphthyridine dimer improved the binding property to the GGA/GGA motif as compared with non-amidated naphthyridine dimer.
    Keywords:  DNA-binding small molecule; Mismatched base pair; Spinocerebellar ataxia type 31; TGGAA pentanucleotide repeats
  41. Cells. 2022 Nov 12. pii: 3583. [Epub ahead of print]11(22):
      Vitiligo is a complex disease wherein derangements in multiple pathways determine the loss of functional melanocytes. Since its pathogenesis is not yet completely understood, vitiligo lacks a definitive safe and efficacious treatment. At present, different therapies are available; however, each modality has its baggage of disadvantages and side effects. Recently we have described several metabolic abnormalities in cells from pigmented skin of vitiligo patients, including alterations of glucose metabolism. Therefore, we conducted a study to evaluate the effect of Pioglitazone (PGZ), a Peroxisome proliferator-activated receptor-γ (PPARγ) agonist, on cells from pigmented vitiligo skin. We treated vitiligo melanocytes and fibroblasts with low doses of PGZ and evaluated the effects on mitochondrial alterations, previously reported by our and other groups. Treatment with PGZ significantly increased mRNA and protein levels of several anaerobic glycolytic enzymes, without increasing glucose consumption. The PGZ administration fully restored the metabolic network, replacing mitochondrial membrane potential and mitochondrial DNA (mtDNA) copy number. These effects, together with a significant increase in ATP content and a decrease in reactive oxygen species (ROS) production, provide strong evidence of an overall improvement of mitochondria bioenergetics in vitiligo cells. Moreover, the expression of HMGB1, Hsp70, defined as a part of DAMPs, and PD-L1 were significantly reduced. In addition, PGZ likely reverts premature senescence phenotype. In summary, the results outline a novel mode of action of Pioglitazone, which may turn out to be relevant to the development of effective new vitiligo therapeutic strategies.
    Keywords:  PPARγ; cellular metabolism; fibroblasts; glucose metabolism; melanocytes; metabolic impairment; pioglitazone; vitiligo