bims-mitdis 2022-09-18 papers

bims-mitdis

Biomed News

on Mitochondrial disorders

Issue of 2022‒09‒18
28 papers selected by
Catalina Vasilescu
University of Helsinki

OMA1-mediated integrated stress response protects against ferroptosis in mitochondrial cardiomyopathy.
Stimulating the sir2-pgc-1α axis rescues exercise capacity and mitochondrial respiration in Drosophila tafazzin mutants.
Tumburu L, Ghosh-Choudhary S, Seifuddin FT, et al. Circulating mitochondrial DNA is a proinflammatory DAMP in sickle cell disease. Blood. 2021;137(22):3116-3126.
Making the leap from structure to mechanism: are the open states of mammalian complex I identified by cryoEM resting states or catalytic intermediates?
Mitochondrial autophagy in the sleeping brain.
Qualitative exploration of the lived experience of adults diagnosed with primary mitochondrial disease.
Sensing local energetics to acutely regulate mitophagy in skeletal muscle.
Lamin A/C impairments cause mitochondrial dysfunction by attenuating PGC1α and the NAMPT-NAD+ pathway.
Next generation sequencing of Tunisian Leigh syndrome patients reveals novel variations: impact for diagnosis and treatment.
Overexpression of UCP3 decreases mitochondrial efficiency in mouse skeletal muscle in vivo.
Expansion of the clinical and neuroimaging spectrum associated with NDUFS8-related disorder.
Mitochondrial dysfunction triggers actin polymerization necessary for rapid glycolytic activation.
The emergent role of mitochondrial surveillance in cellular health.
Computational Model of the Effect of Mitochondrial Dysfunction on Excitation-Contraction Coupling in Skeletal Muscle.
Metabolic reprogramming in the OPA1-deficient cells.
ER exit sites (ERES) and ER-mitochondria encounter structures (ERMES) often localize proximally.
Activation of a type I interferon response associated with acute frataxin knockdown in iPSC-derived cardiomyocytes.
How An Assembly Factor Enhances Covalent FAD Attachment to the Flavoprotein Subunit of Complex II.
Clinical spectrum of early onset "Mediterranean" (homozygous p.P131L mutation) mitochondrial neurogastrointestinal encephalomyopathy.
Outcomes of mitochondrial long chain fatty acid oxidation and carnitine defects from a single center metabolic genetics clinic.
Restoration of mitochondria axonal transport by adaptor Disc1 supplementation prevents neurodegeneration and rescues visual function.
Mitochondrial impairment and intracellular reactive oxygen species alter primary cilia morphology.
A promissing mouse model for Friedreich Ataxia progressing like human patients.
TRIM27 is an autophagy substrate facilitating mitochondria clustering and mitophagy via phosphorylated TBK1.
Loss of cardiomyocyte CYB5R3 impairs redox equilibrium and causes sudden cardiac death.
GCAF(TMEM251) regulates lysosome biogenesis by activating the mannose-6-phosphate pathway.
A universal coupling mechanism of respiratory complex I.
High-Throughput Neurite Outgrowth Assay Using GFP-Labeled iPSC-Derived Neurons.

Cell Metab. 2022 Sep 08. pii: S1550-4131(22)00360-6. [Epub ahead of print]

OMA1-mediated integrated stress response protects against ferroptosis in mitochondrial cardiomyopathy.

Sofia Ahola, Pablo Rivera Mejías, Steffen Hermans, Srikanth Chandragiri, Patrick Giavalisco, Hendrik Nolte, Thomas Langer.

  Cardiomyopathy and heart failure are common manifestations in mitochondrial disease caused by deficiencies in the oxidative phosphorylation (OXPHOS) system of mitochondria. Here, we demonstrate that the cardiac-specific loss of the assembly factor Cox10 of the cytochrome c oxidase causes mitochondrial cardiomyopathy in mice, which is associated with OXPHOS deficiency, lysosomal defects, and an aberrant mitochondrial morphology. Activation of the mitochondrial peptidase Oma1 in Cox10-/- mice results in mitochondrial fragmentation and induction of the integrated stress response (ISR) along the Oma1-Dele1-Atf4 signaling axis. Ablation of Oma1 or Dele1 in Cox10-/- mice aggravates cardiomyopathy. ISR inhibition impairs the cardiac glutathione metabolism, limits the selenium-dependent accumulation of the glutathione peroxidase Gpx4, and increases lipid peroxidation in the heart, ultimately culminating in ferroptosis. Our results demonstrate a protective role of the Oma1-Dele1-mediated ISR in mitochondrial cardiomyopathy and link ferroptosis to OXPHOS deficiency and mitochondrial disease.

Keywords:  Atf4; Dele1; Gpx4; Oma1; cardiomyopathy; ferroptosis; glutathione; integrated stress response; mitochondria; selenium

DOI:  https://doi.org/10.1016/j.cmet.2022.08.017
Dis Model Mech. 2022 Sep 15. pii: dmm.049279. [Epub ahead of print]

Stimulating the sir2-pgc-1α axis rescues exercise capacity and mitochondrial respiration in Drosophila tafazzin mutants.

Deena Damschroder, Rubén Zapata-Pérez, Kristin Richardson, Frédéric M Vaz, Riekelt H Houtkooper, Robert Wessells.

  Cardiolipin (CL) is a phospholipid required for proper mitochondrial function. Tafazzin remodels CL to create highly unsaturated fatty acid chains. However, when tafazzin is mutated, CL remodeling is impeded, leading to mitochondrial dysfunction and the disease Barth syndrome. Patients with Barth syndrome often have severe exercise intolerance, which negatively impacts their overall quality of life. Boosting NAD+ levels can improve symptoms of other mitochondrial diseases, but its effect in the context of Barth syndrome has not been examined. We demonstrate for the first time that nicotinamide riboside (NR) can rescue exercise tolerance and mitochondrial respiration in a Drosophila tafazzin mutant and that the beneficial effects are dependent on sir2 and pgc-1α. Overexpressing pgc-1α increased the total abundance of cardiolipin in mutants. In addition, muscles and neurons were identified as key targets for future therapies because sir2 or pgc-1α overexpression in either of these tissues is sufficient to restore the exercise capacity of Drosophila tafazzin mutants.

Keywords:  Barth syndrome; Drosophila; Exercise Tolerance; NAD; Nicotinamdie Riboside; Tafazzin

DOI:  https://doi.org/10.1242/dmm.049279
Blood. 2022 Sep 15. 140(11): 1327

Tumburu L, Ghosh-Choudhary S, Seifuddin FT, et al. Circulating mitochondrial DNA is a proinflammatory DAMP in sickle cell disease. Blood. 2021;137(22):3116-3126.

DOI: https://doi.org/10.1182/blood.2021012839
Curr Opin Struct Biol. 2022 Sep 07. pii: S0959-440X(22)00126-9. [Epub ahead of print]77 102447

Making the leap from structure to mechanism: are the open states of mammalian complex I identified by cryoEM resting states or catalytic intermediates?

Injae Chung, Daniel N Grba, John J Wright, Judy Hirst.

Respiratory complex I (NADH:ubiquinone oxidoreductase) is a multi-subunit, energy-transducing mitochondrial enzyme that is essential for oxidative phosphorylation and regulating NAD+/NADH pools. Despite recent advances in structural knowledge and a long history of biochemical analyses, the mechanism of redox-coupled proton translocation by complex I remains unknown. Due to its ability to separate molecules in a mixed population into distinct classes, single-particle electron cryomicroscopy has enabled identification and characterisation of different complex I conformations. However, deciding on their catalytic and/or regulatory properties to underpin mechanistic hypotheses, especially without detailed biochemical characterisation of the structural samples, has proven challenging. In this review we explore different mechanistic interpretations of the closed and open states identified in cryoEM analyses of mammalian complex I.

DOI: https://doi.org/10.1016/j.sbi.2022.102447
Front Cell Dev Biol. 2022 ;10 956394

Mitochondrial autophagy in the sleeping brain.

Sofia Mauri, Mariavittoria Favaro, Greta Bernardo, Gabriella M Mazzotta, Elena Ziviani.

  A significant percentage of the mitochondrial mass is replaced on a daily basis via mechanisms of mitochondrial quality control. Through mitophagy (a selective type of autophagy that promotes mitochondrial proteostasis) cells keep a healthy pool of mitochondria, and prevent oxidative stress and inflammation. Furthermore, mitophagy helps adapting to the metabolic demand of the cells, which changes on a daily basis. Core components of the mitophagy process are PINK1 and Parkin, which mutations are linked to Parkinson's Disease. The crucial role of PINK1/Parkin pathway during stress-induced mitophagy has been extensively studied in vitro in different cell types. However, recent advances in the field allowed discovering that mitophagy seems to be only slightly affected in PINK1 KO mice and flies, putting into question the physiological relevance of this pathway in vivo in the whole organism. Indeed, several cell-specific PINK1/Parkin-independent mitophagy pathways have been recently discovered, which appear to be activated under physiological conditions such as those that promote mitochondrial proteome remodeling during differentiation or in response to specific physiological stimuli. In this Mini Review we want to summarize the recent advances in the field, and add another level of complexity by focusing attention on a potentially important aspect of mitophagy regulation: the implication of the circadian clock. Recent works showed that the circadian clock controls many aspects of mitochondrial physiology, including mitochondrial morphology and dynamic, respiratory activity, and ATP synthesis. Furthermore, one of the essential functions of sleep, which is controlled by the clock, is the clearance of toxic metabolic compounds from the brain, including ROS, via mechanisms of proteostasis. Very little is known about a potential role of the clock in the quality control mechanisms that maintain the mitochondrial repertoire healthy during sleep/wake cycles. More importantly, it remains completely unexplored whether (dys)function of mitochondrial proteostasis feedbacks to the circadian clockwork.

Keywords:  Parkinson’s disease; animal models; circadian rhythms; mitophagy; proteostasis

DOI:  https://doi.org/10.3389/fcell.2022.956394
JIMD Rep. 2022 Sep;63(5): 494-507

Qualitative exploration of the lived experience of adults diagnosed with primary mitochondrial disease.

Kathleen D Valverde, Elizabeth M McCormick, Marni J Falk.

  Primary mitochondrial disease (PMD) encompasses a heterogeneous group of energy deficiency disorders that are typically progressive, with affected individuals experiencing an average of 16 multisystem symptoms. Clinical trials are emerging, but current treatment options remain limited. In PMD, the effect of specific disease factors and their relationship to meaning-based coping has not been studied. Given the connection between prognostic uncertainty and psychological distress in other patient populations, we explored the lived experience of adults with PMD. Adults with PMD caused by pathogenic variant(s) in nuclear or mitochondrial genes impairing mitochondrial function were interviewed. Interview questions addressed the lived experience with PMD, diagnostic journey, practical learnings at the time of diagnosis, suggestions for supportive information to provide at diagnosis, diagnosis impact on daily living and self-care, and sources of support and hope. Focus group transcripts were analyzed using thematic analysis. Four themes (diagnostic challenges, adaptations to daily living, social implications, and meaning-based coping) and several subthemes (the importance of being hopeful and benefit finding) emerged. Most participants reported strong family support (9/14) and identified a benefit (9/14) derived from their PMD diagnosis, while (5/14) did not identify any benefits. Benefit finding, reframing, and maintaining a positive attitude emerged as common coping in adults living with PMD. Understanding how adults with PMD cope is essential to provide anticipatory guidance and ongoing support for those struggling with their disease diagnosis, progression, and broader life impact. Our findings suggest that adult PMD patients prefer healthcare providers to inquire about their emotional well-being and meaning based coping with PMD.

Keywords:  benefit finding; chronic illness; lived experience; meaning based coping; resiliency

DOI:  https://doi.org/10.1002/jmd2.12316
Front Cell Dev Biol. 2022 ;10 987317

Sensing local energetics to acutely regulate mitophagy in skeletal muscle.

Anna S Nichenko, Kalyn S Specht, Siobhan M Craige, Joshua C Drake.

  The energetic requirements of skeletal muscle to sustain movement, as during exercise, is met largely by mitochondria, which form an intricate, interconnected reticulum. Maintenance of a healthy mitochondrial reticulum is essential for skeletal muscle function, suggesting quality control pathways are spatially governed. Mitophagy, the process by which damaged and/or dysfunctional regions of the mitochondrial reticulum are removed and degraded, has emerged as an integral part of the molecular response to exercise. Upregulation of mitophagy in response to acute exercise is directly connected to energetic sensing mechanisms through AMPK. In this review, we discuss the connection of mitophagy to muscle energetics and how AMPK may spatially control mitophagy through multiple potential means.

Keywords:  AMPK; energetic stress; mitochondria; mitophagy; reactive oxygen species

DOI:  https://doi.org/10.3389/fcell.2022.987317
Nucleic Acids Res. 2022 Sep 13. pii: gkac741. [Epub ahead of print]

Lamin A/C impairments cause mitochondrial dysfunction by attenuating PGC1α and the NAMPT-NAD+ pathway.

Scott Maynard, Arnaldur Hall, Panagiotis Galanos, Salvatore Rizza, Tatsuro Yamamoto, Helena Hagner Gram, Sebastian H N Munk, Muhammad Shoaib, Claus Storgaard Sørensen, Vilhelm A Bohr, Mads Lerdrup, Apolinar Maya-Mendoza, Jiri Bartek.

Mutations in the lamin A/C gene (LMNA) cause laminopathies such as the premature aging Hutchinson Gilford progeria syndrome (HGPS) and altered lamin A/C levels are found in diverse malignancies. The underlying lamin-associated mechanisms remain poorly understood. Here we report that lamin A/C-null mouse embryo fibroblasts (Lmna-/- MEFs) and human progerin-expressing HGPS fibroblasts both display reduced NAD+ levels, unstable mitochondrial DNA and attenuated bioenergetics. This mitochondrial dysfunction is associated with reduced chromatin recruitment (Lmna-/- MEFs) or low levels (HGPS) of PGC1α, the key transcription factor for mitochondrial homeostasis. Lmna-/- MEFs showed reduced expression of the NAD+-biosynthesis enzyme NAMPT and attenuated activity of the NAD+-dependent deacetylase SIRT1. We find high PARylation in lamin A/C-aberrant cells, further decreasing the NAD+ pool and consistent with impaired DNA base excision repair in both cell models, a condition that fuels DNA damage-induced PARylation under oxidative stress. Further, ATAC-sequencing revealed a substantially altered chromatin landscape in Lmna-/- MEFs, including aberrantly reduced accessibility at the Nampt gene promoter. Thus, we identified a new role of lamin A/C as a key modulator of mitochondrial function through impairments of PGC1α and the NAMPT-NAD+ pathway, with broader implications for the aging process.

DOI: https://doi.org/10.1093/nar/gkac741
Biosci Rep. 2022 Sep 12. pii: BSR20220194. [Epub ahead of print]

Next generation sequencing of Tunisian Leigh syndrome patients reveals novel variations: impact for diagnosis and treatment.

Meriem Hechmi, Majida Charif, Ichraf Kraoua, Meriem Fassatoui, Hamza Dallali, Valerie Desquiret-Dumas, Céline Bris, David Goudenège, Cyrine Drissi, Saïd Galai, Slah Ouerhani, Vincent Procaccio, Patrizia Amati-Bonneau, Sonia Abdelhak, Ilhem Ben Youssef-Turki, Guy Lenaers, Rym Kefi.

  Mitochondrial cytopathies, among which the Leigh syndrome (LS), are caused by variants either in the mitochondrial or the nuclear genome, affecting the oxidative phosphorylation process. The aim of this study consisted in defining the molecular diagnosis of a group of Tunisian patients with LS. Six children, belonging to five Tunisian families, with clinical and imaging presentations suggestive of LS were recruited. Whole mitochondrial DNA and targeted next generation sequencing of a panel of 281 nuclear genes involved in mitochondrial physiology were performed. Bioinformatic analyses were achieved in order to identify deleterious variations. A single m.10197G>A (p.Ala47Thr) variant was found in the mitochondrial MT-ND3 gene in one patient, while the others were related to autosomal homozygous variants: two c.1412delA (p.Gln471ArgfsTer42) and c.1264A>G (p.Thr422Ala) in SLC19A3, one c.454C>G (p.Pro152Ala) in SLC25A19 and one c.122G>A (p.Gly41Asp) in ETHE1. Our findings demonstrate the usefulness of genomic investigations to improve LS diagnosis in consanguineous populations, and further allow for treating the patients harboring variants in SLC19A3 and SLC25A19 that contribute to thiamine transport, by thiamine and biotin supplementation. Considering the Tunisian genetic background, the newly identified variants could be screened in patients with similar clinical presentation in related populations.

Keywords:  Leigh syndrome; NGS; North Africa; Tunisia; mitochondrial cytopathies

DOI:  https://doi.org/10.1042/BSR20220194
FEBS Lett. 2022 Sep 16.

Overexpression of UCP3 decreases mitochondrial efficiency in mouse skeletal muscle in vivo.

Roberto Codella, Tiago C Alves, Douglas E Befroy, Cheol Soo Choi, Livio Luzi, Douglas L Rothman, Richard G Kibbey, Gerald I Shulman.

  Uncoupling protein-3 (UCP3) is a mitochondrial transmembrane protein highly expressed in muscle that has been implicated in regulating the efficiency of mitochondrial oxidative phosphorylation. Increasing UCP3 expression in skeletal muscle enhances proton leak across the inner mitochondrial membrane and increases oxygen consumption in isolated mitochondria, but its precise function in vivo has yet to be fully elucidated. To examine whether muscle-specific overexpression of UCP3 modulates muscle mitochondrial oxidation in vivo, rates of ATP synthesis were assessed by 31 P magnetic resonance spectroscopy (MRS) and rates of mitochondrial oxidative metabolism were measured by assessing the rate of [2-13 C]acetate incorporation into muscle [4-13 C]- , [3-13 C]-glutamate and [4-13 C]-glutamine by high resolution 13 C/1 H MRS. Using this approach we found that overexpression of UCP3 in skeletal muscle was accompanied by increased muscle mitochondrial inefficiency in vivo as reflected by a 42% reduction in the ratio of ATP synthesis to mitochondrial oxidation.

Keywords:  magnetic resonance spectroscopy; mitochondrial efficiency; mitochondrial uncoupling; muscle energy metabolism

DOI:  https://doi.org/10.1002/1873-3468.14494
JIMD Rep. 2022 Sep;63(5): 391-399

Expansion of the clinical and neuroimaging spectrum associated with NDUFS8-related disorder.

Milena M Andzelm, Shanti Balasubramaniam, Edward Yang, Alison G Compton, Kate Millington, Jia Zhu, Irina Anselm, Lance H Rodan, David R Thorburn, John Christodoulou, Siddharth Srivastava.

  Biallelic pathogenic variants in NDUFS8, a nuclear gene encoding a subunit of mitochondrial complex I, result in a mitochondrial disorder characterized by varying clinical presentations and severity. Here, we expand the neuroimaging and clinical spectrum of NDUFS8-related disorder. We present three cases from two unrelated families (a girl and two brothers) homozygous for a recurrent pathogenic NDUFS8 variant [c.460G>A, p.(Gly154Ser)], located in the [4Fe-4S] domain of the protein. One of the patients developed auto-antibody positive diabetic ketoacidosis. Brain MRIs performed in two of the three patients demonstrated diffuse cerebral and cerebellar white matter involvement including corticospinal tracts, but notably had sparing of deep gray matter structures. Our report expands the neuroimaging phenotype of NDUFS8-related disorder to include progressive leukodystrophy with increasing brainstem and cerebellar involvement, with relative sparing of the basal ganglia. In addition, we describe autoimmune diabetes in association with NDUFS8-related disorder, though the exact mechanism of this association is unclear. This paper provides a comprehensive review of case presentation and progressive neuroimaging findings of three patients from two unrelated families that have an identical pathogenic NDUFS8 variant, which expands the clinical spectrum of NDUFS8-associated neurological disease.

Keywords:  NDUFS8; autoimmune diabetes; mitochondrial disorder; progressive leukodystrophy

DOI:  https://doi.org/10.1002/jmd2.12303
J Cell Biol. 2022 Nov 07. pii: e202201160. [Epub ahead of print]221(11):

Mitochondrial dysfunction triggers actin polymerization necessary for rapid glycolytic activation.

Rajarshi Chakrabarti, Tak Shun Fung, Taewook Kang, Pieti W Elonkirjo, Anu Suomalainen, Edward J Usherwood, Henry N Higgs.

Mitochondrial damage represents a dramatic change in cellular homeostasis. One rapid response is perimitochondrial actin polymerization, termed acute damage-induced actin (ADA). The consequences of ADA are not understood. In this study, we show evidence suggesting that ADA is linked to rapid glycolytic activation upon mitochondrial damage in multiple cells, including mouse embryonic fibroblasts and effector CD8+ T lymphocytes. ADA-inducing treatments include CCCP, antimycin, rotenone, oligomycin, and hypoxia. The Arp2/3 complex inhibitor CK666 or the mitochondrial sodium-calcium exchanger (NCLX) inhibitor CGP37157 inhibits both ADA and the glycolytic increase within 5 min, supporting ADA's role in glycolytic stimulation. Two situations causing chronic reductions in mitochondrial ATP production, mitochondrial DNA depletion and mutation to the NDUFS4 subunit of complex 1 of the electron transport chain, cause persistent perimitochondrial actin filaments similar to ADA. CK666 treatment causes rapid mitochondrial actin loss and a drop in ATP in NDUFS4 knock-out cells. We propose that ADA is necessary for rapid glycolytic activation upon mitochondrial impairment, to re-establish ATP production.

DOI: https://doi.org/10.1083/jcb.202201160
Aging Cell. 2022 Sep 11. e13710

The emergent role of mitochondrial surveillance in cellular health.

Elissa Tjahjono, Daniel R Kirienko, Natalia V Kirienko.

  Mitochondrial dysfunction is one of the primary causatives for many pathologies, including neurodegenerative diseases, cancer, metabolic disorders, and aging. Decline in mitochondrial functions leads to the loss of proteostasis, accumulation of ROS, and mitochondrial DNA damage, which further exacerbates mitochondrial deterioration in a vicious cycle. Surveillance mechanisms, in which mitochondrial functions are closely monitored for any sign of perturbations, exist to anticipate possible havoc within these multifunctional organelles with primitive origin. Various indicators of unhealthy mitochondria, including halted protein import, dissipated membrane potential, and increased loads of oxidative damage, are on the top of the lists for close monitoring. Recent research also indicates a possibility of reductive stress being monitored as part of a mitochondrial surveillance program. Upon detection of mitochondrial stress, multiple mitochondrial stress-responsive pathways are activated to promote the transcription of numerous nuclear genes to ameliorate mitochondrial damage and restore compromised cellular functions. Co-expression occurs through functionalization of transcription factors, allowing their binding to promoter elements to initiate transcription of target genes. This review provides a comprehensive summary of the intricacy of mitochondrial surveillance programs and highlights their roles in our cellular life. Ultimately, a better understanding of these surveillance mechanisms is expected to improve healthspan.

Keywords:  aging; mitochondria; mitochondrial membrane transport proteins; mitophagy; physiological stress; reactive oxygen species; surveillance

DOI:  https://doi.org/10.1111/acel.13710
Bull Math Biol. 2022 Sep 17. 84(11): 123

Computational Model of the Effect of Mitochondrial Dysfunction on Excitation-Contraction Coupling in Skeletal Muscle.

Sageanne Senneff, Madeleine M Lowery.

  It has become well established that mitochondria not only regulate myoplasmic calcium in skeletal muscle, but also use that calcium to stimulate oxidative phosphorylation (OXPHOS). While experimental approaches have allowed for imaging of mitochondrial calcium and membrane potentials in isolated fibers, capturing the role of mitochondria and the impact of mitochondrial impairments on excitation-contraction coupling (ECC) remains difficult to explore in intact muscle. Computational models have been widely used to examine the structure and function of skeletal muscle contraction; however, models of ECC to date lack communication between the myoplasm and mitochondria for regulating calcium and ATP during sustained contractions. To address this, a mathematical model of mitochondrial calcium handling and OXPHOS was integrated into a physiological model of ECC incorporating action potential propagation, calcium handling between the sarcoplasmic reticulum (SR) and the myoplasm, and crossbridge cycling. The model was used to examine the protective role of mitochondria during repeated stimulation and the impact of mitochondrial dysfunction on ECC resulting from progressive OXPHOS inhibition. Pathological myoplasmic calcium accumulation occurred through distinct mechanisms in the model in the case of either electron transport chain, F1F0 ATP synthase, or adenine nucleotide transporter impairments. To investigate the effect of each impairment on force, a model of calcium-stimulated apoptosis was utilized to capture dysfunction-induced reductions in muscle mass, driving whole muscle force loss. The model presented in this study can be used to examine the role of mitochondria in the regulation of calcium, ATP, and force generation during voluntary contraction.

Keywords:  Apoptosis; Calcium dynamics; Force; Mathematical modeling; Muscle weakness

DOI:  https://doi.org/10.1007/s11538-022-01079-3
Cell Mol Life Sci. 2022 Sep 14. 79(10): 517

Metabolic reprogramming in the OPA1-deficient cells.

Wenting Dai, Zhichao Wang, Qiong A Wang, David Chan, Lei Jiang.

  OPA1, a dynamin-related GTPase mutated in autosomal dominant optic atrophy, is essential for the fusion of the inner mitochondrial membrane. Although OPA1 deficiency leads to impaired mitochondrial morphology, the role of OPA1 in central carbon metabolism remains unclear. Here, we aim to explore the functional role and metabolic mechanism of OPA1 in cell fitness beyond the control of mitochondrial fusion. We applied [U-13C]glucose and [U-13C]glutamine isotope tracing techniques to OPA1-knockout (OPA1-KO) mouse embryonic fibroblasts (MEFs) compared to OPA1 wild-type (OPA1-WT) controls. Furthermore, the resulting tracing data were integrated by metabolic flux analysis to understand the underlying metabolic mechanism through which OPA1 deficiency reprograms cellular metabolism. OPA1-deficient MEFs were depleted of intracellular citrate, which was consistent with the decreased oxygen consumption rate in these cells with mitochondrial fission that is not balanced by mitochondrial fusion. Whereas oxidative glucose metabolism was impaired, OPA1-deficient cells activated glutamine-dependent reductive carboxylation and subsequently relied on this reductive metabolism to produce cytosolic citrate as a predominant acetyl-CoA source for de novo fatty acid synthesis. Prevention of cytosolic glutamine reductive carboxylation by GSK321, an inhibitor of isocitrate dehydrogenase 1 (IDH1), largely repressed lipid synthesis and blocked cell proliferation in OPA1-deficient MEFs. Our data support that, when glucose oxidation failed to support lipogenesis and proliferation in cells with unbalanced mitochondrial fission, OPA1 deficiency stimulated metabolic anaplerosis into glutamine-dependent reductive carboxylation in an IDH1-mediated manner.

Keywords:  Cell growth; Citrate; De novo lipogenesis; OPA1 dysfunction; Oxidative metabolism; Reductive carboxylation

DOI:  https://doi.org/10.1007/s00018-022-04542-5
FEBS Lett. 2022 Sep 14.

ER exit sites (ERES) and ER-mitochondria encounter structures (ERMES) often localize proximally.

Naini Chakraborty, Bhawik Kumar Jain, Samruddhi Shembekar, Dibyendu Bhattacharyya.

To understand the potential interplay between vesicular trafficking and direct membrane contact sites mediated transport, we selected the endoplasmic reticulum (ER), which participates in both modes of inter-organelle transport. ER-mitochondria encounter structures (ERMES) are direct membrane contact junctions that mediate macromolecule exchange, while the secretory pathway originates at ER exit sites (ERES). Using the budding yeast Pichia pastoris, we documented that ERMES resident proteins are often juxtaposed with ERES markers. We further demonstrated that ERES form de novo almost always near a pre-existing ERMES. Disruption of either ERES or ERMES affects the other. Djp1, a chaperone reported to mediate mitochondrial import of ER-resident proteins, localizes at the ERES-ERMES proximal region. Our results indicate a potential functional link between ERES-ERMES proximity and mitochondrial protein import.

DOI: https://doi.org/10.1002/1873-3468.14497
Dis Model Mech. 2022 Sep 15. pii: dmm.049497. [Epub ahead of print]

Activation of a type I interferon response associated with acute frataxin knockdown in iPSC-derived cardiomyocytes.

M Grazia Cotticelli, Shujuan Xia, Rachel Truitt, Nicolai M Doliba, Andrea V Rozo, John W Tobias, Taehee Lee, Justin Chen, Jill S Napierala, Marek Napierala, Wenli Yang, Robert B Wilson.

  Friedreich ataxia, the most common hereditary ataxia, is a neuro- and cardio-degenerative disorder caused, in most cases, by decreased expression of the mitochondrial protein frataxin. Cardiomyopathy is the leading cause of premature death. Frataxin functions in the biogenesis of iron-sulfur clusters, which are prosthetic groups that are found in proteins involved in many biological processes. To study the changes associated with decreased frataxin in human cardiomyocytes, we developed a novel isogenic model by acutely knocking down frataxin, post-differentiation, in cardiomyocytes derived from induced pluripotent stem cells. Transcriptome analysis of four biological replicates identified severe mitochondrial dysfunction and a type I interferon response as the pathways most affected by frataxin knockdown. We confirmed that in iPSC-derived cardiomyocytes, loss of frataxin leads to mitochondrial dysfunction. The type I interferon response was activated in multiple cell types following acute frataxin knockdown and was caused, at least in part, by release of mitochondrial DNA into the cytosol, activating the cGAS-STING sensor pathway.

Keywords:  Cardiomyopathy; Friedreich; Innate Immunity; Interferon; mtDNA

DOI:  https://doi.org/10.1242/dmm.049497
J Biol Chem. 2022 Sep 08. pii: S0021-9258(22)00915-2. [Epub ahead of print] 102472

How An Assembly Factor Enhances Covalent FAD Attachment to the Flavoprotein Subunit of Complex II.

Elena Maklashina, T M Iverson, Gary Cecchini.

  The membrane-bound complex II family of proteins is composed of enzymes that catalyze succinate and fumarate interconversion coupled with reduction or oxidation of quinones within the membrane domain. The majority of complex II enzymes are protein heterotetramers with the different subunits harboring a variety of redox centers. These redox centers are used to transfer electrons between the site of succinate-fumarate oxidation/reduction and the membrane domain harboring the quinone. A covalently bound FAD cofactor is present in the flavoprotein subunit, and the covalent flavin linkage is absolutely required to enable the enzyme to oxidize succinate. Assembly of the covalent flavin linkage in eukaryotic cells and many bacteria requires additional protein assembly factors. Here, we provide mechanistic details for how the assembly factors work to enhance covalent flavinylation. Both prokaryotic SdhE and mammalian SDHAF2 enhance FAD binding to their respective apo-protein of complex II. These assembly factors also increase the affinity for dicarboxylates to the apo-protein-non-covalent FAD complex and stabilize the pre-assembly complex. These findings are corroborated by previous investigations of the roles of SdhE in enhancing covalent flavinylation in both bacterial succinate dehydrogenase and fumarate reductase flavoprotein subunits and of SDHAF2 in performing the same function for the human mitochondrial succinate dehydrogenase flavoprotein. In conclusion, we provide further insight into assembly factor involvement in building the complex II flavoprotein subunit active site required for succinate oxidation.

Keywords:  Succinate dehydrogenase; complex II; covalent flavins; fumarate reductase; mitochondrial assembly factors

DOI:  https://doi.org/10.1016/j.jbc.2022.102472
JIMD Rep. 2022 Sep;63(5): 484-493

Clinical spectrum of early onset "Mediterranean" (homozygous p.P131L mutation) mitochondrial neurogastrointestinal encephalomyopathy.

Sema Kalkan Uçar, Havva Yazıcı, Ebru Canda, Esra Er, Fatma Derya Bulut, Cenk Eraslan, Hüseyin Onay, Bridget Elizabeth Bax, Mahmut Çoker.

  Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) is an autosomal recessive mitochondrial disorder characterized by cumulative and progressive gastrointestinal and neurological findings. This retrospective observational study, aimed to explore the time of presentation, diagnosis and clinical follow-up of 13 patients with a confirmed MNGIE disease of Mediterranean origin. The mean age of symptom onset was 7 years (6 months-21 years) and the average diagnosis age was 15.4 years ±8.4. Four of 13 patients (30%) died before 30 years at the mean age of 19.7 years ±6.8. Cachexia and gastrointestinal symptoms were observed in all patients (100%). The mean body mass index standard deviation score at diagnosis was 4.8 ± 2.8. At least three subocclusive episodes were presented in patients who died in last year of their life. The main neurological symptom found in most patients was peripheral neuropathy (92%). Ten patients (77%) had leukoencephalopathy and the remaining three patients without were under 10 years of age. The new homozygous "Mediterranean" TYMP mutation, p.P131L (c.392 C > T) was associated with an early presentation and poor prognosis in nine patients (69%) from five separates families. Based on the observations from this Mediterranean MNGIE cohort, we propose that the unexplained abdominal pain combined with cachexia is an indicator of MNGIE. High-platelet counts and nerve conduction studies may be supportive laboratory findings and the frequent subocclusive episodes could be a negative prognostic factor for mortality. Finally, the homozygous p.P131L (c.392 C > T) mutation could be associated with rapid progressive disease with poor prognosis.

Keywords:  clinical overview; mitochondrial neurogastrointestinal encephalomyopathy; thymidine phosphorylase

DOI:  https://doi.org/10.1002/jmd2.12315
Orphanet J Rare Dis. 2022 Sep 15. 17(1): 360

Outcomes of mitochondrial long chain fatty acid oxidation and carnitine defects from a single center metabolic genetics clinic.

Anastasia Ambrose, Melissa Sheehan, Shalini Bahl, Taryn Athey, Shailly Ghai-Jain, Alicia Chan, Saadet Mercimek-Andrews.

  BACKGROUND: Mitochondrial long-chain fatty acid oxidation and carnitine metabolism defects are a group of inherited metabolic diseases. We performed a retrospective cohort study to report on the phenotypic and genotypic spectrum of mitochondrial long-chain fatty acid oxidation and carnitine metabolism defects as well as their treatment outcomes.METHODS: All patients with mitochondrial long-chain fatty acid oxidation and carnitine metabolism defects were included. We divided patients into two groups to compare outcomes of those treated symptomatically (SymX) and asymptomatically (AsymX). We reviewed patient charts for clinical features, biochemical investigations, molecular genetic investigations, cardiac assessments, neuroimaging, treatments, and outcomes.
RESULTS: There were 38 patients including VLCAD (n = 5), LCHAD (n = 4), CACT (n = 3), MAD (n = 1), CPT-I (n = 13), CPT-II (n = 3) deficiencies and CTD (n = 9). Fourteen patients were diagnosed symptomatically (SymX), and 24 patients were diagnosed asymptomatically (AsymX). Twenty-eight variants in seven genes were identified in 36 patients (pathogenic/likely pathogenic n = 25; variant of unknown significance n = 3). Four of those variants were novel. All patients with LCHAD deficiency had the common variant (p.Glu474Gln) in HADHA and their phenotype was similar to the patients reported in the literature for this genotype. Only one patient with VLCAD deficiency had the common p.Val283Ala in ACADVL. The different genotypes in the SymX and AsymX groups for VLCAD deficiency presented with similar phenotypes. Eight patients were treated with carnitine supplementation [CTD (n = 6), CPT-II (n = 1), and MAD (n = 1) deficiencies]. Thirteen patients were treated with a long-chain fat restricted diet and MCT supplementation. A statistically significant association was found between rhabdomyolysis, and hypoglycemia in the SymX group compared to the AsymX group. A higher number of hospital admissions, longer duration of hospital admissions and higher CK levels were observed in the SymX group, even though the symptomatic group was only 37% of the study cohort.
CONCLUSION: Seven different mitochondrial long-chain fatty acid oxidation and carnitine metabolism defects were present in our study cohort. In our clinic, the prevalence of mitochondrial long-chain fatty acid oxidation and carnitine defects was 4.75%.

Keywords:  Carnitine metabolism defects; Long-chain fat restricted diet; Medium chain triglycerides; Mitochondrial long-chain fatty acid oxidation; Newborn screening

DOI:  https://doi.org/10.1186/s13023-022-02512-5
Cell Rep. 2022 Sep 13. pii: S2211-1247(22)01148-2. [Epub ahead of print]40(11): 111324

Restoration of mitochondria axonal transport by adaptor Disc1 supplementation prevents neurodegeneration and rescues visual function.

Heberto Quintero, Yukihiro Shiga, Nicolas Belforte, Luis Alarcon-Martinez, Sana El Hajji, Deborah Villafranca-Baughman, Florence Dotigny, Adriana Di Polo.

  Deficits in mitochondrial transport are a common feature of neurodegenerative diseases. We investigated whether loss of components of the mitochondrial transport machinery impinge directly on metabolic stress, neuronal death, and circuit dysfunction. Using multiphoton microscope live imaging, we showed that ocular hypertension, a major risk factor in glaucoma, disrupts mitochondria anterograde axonal transport leading to energy decline in vulnerable neurons. Gene- and protein-expression analysis revealed loss of the adaptor disrupted in schizophrenia 1 (Disc1) in retinal neurons subjected to high intraocular pressure. Disc1 gene delivery was sufficient to rescue anterograde transport and replenish axonal mitochondria. A genetically encoded ATP sensor combined with longitudinal live imaging showed that Disc1 supplementation increased ATP production in stressed neurons. Disc1 gene therapy promotes neuronal survival, reverses abnormal single-cell calcium dynamics, and restores visual responses. Our study demonstrates that enhancing anterograde mitochondrial transport is an effective strategy to alleviate metabolic stress and neurodegeneration.

Keywords:  CP: Neuroscience; disrupted in schizophrenia 1; glaucoma; metabolic stress; mitochondria axonal transport; neuronal ATP production; neuroprotection; retinal ganglion cell; vision restoration

DOI:  https://doi.org/10.1016/j.celrep.2022.111324
Life Sci Alliance. 2022 Dec;pii: e202201505. [Epub ahead of print]5(12):

Mitochondrial impairment and intracellular reactive oxygen species alter primary cilia morphology.

Noah Moruzzi, Ismael Valladolid-Acebes, Sukanya A Kannabiran, Sara Bulgaro, Ingo Burtscher, Barbara Leibiger, Ingo B Leibiger, Per-Olof Berggren, Kerstin Brismar.

Primary cilia have recently emerged as cellular signaling organelles. Their homeostasis and function require a high amount of energy. However, how energy depletion and mitochondria impairment affect cilia have barely been addressed. We first studied the spatial relationship between a mitochondria subset in proximity to the cilium in vitro, finding similar mitochondrial activity measured as mitochondrial membrane potential compared with the cellular network. Next, using common primary cilia cell models and inhibitors of mitochondrial energy production, we found alterations in cilia number and/or length due to energy depletion and mitochondrial reactive oxygen species (ROS) overproduction. Finally, by using a mouse model of type 2 diabetes mellitus, we provided in vivo evidence that cilia morphology is impaired in diabetic nephropathy, which is characterized by ROS overproduction and impaired mitochondrial metabolism. In conclusion, we showed that energy imbalance and mitochondrial ROS affect cilia morphology and number, indicating that conditions characterized by mitochondria and radicals imbalances might lead to ciliary impairment.

DOI: https://doi.org/10.26508/lsa.202201505
Behav Brain Res. 2022 Sep 08. pii: S0166-4328(22)00375-8. [Epub ahead of print] 114107

A promissing mouse model for Friedreich Ataxia progressing like human patients.

Catherine Gérard, Annabelle Fortin Archambault, Camille Bouchard, Jacques P Tremblay.

  Friedreich Ataxia (FRDA) is a genetic disease caused by an expended GAA repeat in the FXN gene leading to a reduction in frataxin protein production. Frataxin is an essential protein involved in mitochondrial iron-sulfur-cluster formation, its absence affecting numerous cellular rections. In patients, the disease leads to a progressive neuromuscular degeneration and, most of the time, death from heart failure. In order to determine if a treatment is effective or not, it is essential to have the mouse model, which best reflects all of the characteristics of this disease. Many groups were working on the creation of mouse models by decreasing the mouse frataxin or knocking it out, by introducing a transgene with a human frataxin with long GAA repeat. Most of the mouse models are limited to one problem, either neurologic or cardiac symptoms, and, for those who have both, generally these symptoms are too severe and mice have a very short life span, which does not reflect the human disease's progression. Jackson Laboratories Inc. developed a new mouse model that has 800 GAA repeats. We demonstrate here that these mice accurately reflect the human disease with a progressive neuromuscular degeneration highlighted by the two beam tests and the beginning of heart hypertrophy at 26 weeks. YG8-800 mice are thus currently a promising mouse model for FRDA.

Keywords:  Friedreich Ataxia; behavior test; cardiac hypertrophy; frataxin; mouse model

DOI:  https://doi.org/10.1016/j.bbr.2022.114107
FEBS J. 2022 Sep 16.

TRIM27 is an autophagy substrate facilitating mitochondria clustering and mitophagy via phosphorylated TBK1.

Juncal Garcia-Garcia, Anne Kristin McLaren Berge, Katrine Stange Overå, Kenneth Bowitz Larsen, Zambarlal Bhujabal, Andreas Brech, Yakubu Princely Abudu, Trond Lamark, Terje Johansen, Eva Sjøttem.

Tripartite motif containing protein 27 (TRIM27/also called RFP) is a multifunctional ubiquitin E3 ligase involved in numerous cellular functions, such as proliferation, apoptosis, regulation of the NF-kB pathway, endosomal recycling, and the innate immune response. TRIM27 interacts directly with TANK-binding kinase 1 (TBK1) and regulates its stability. TBK1 in complex with autophagy receptors are recruited to ubiquitin chains assembled on the mitochondrial outer membrane promoting mitophagy. Here we identify TRIM27 as an autophagy substrate, depending on ATG7, ATG9 and autophagy receptors for its lysosomal degradation. We show that TRIM27 forms ubiquitylated cytoplasmic bodies that colocalize with autophagy receptors. Surprisingly, we observed that induced expression of EGFP-TRIM27 in HEK293 FlpIn TRIM27 Knock-Out cells mediates mitochondrial clustering. TRIM27 interacts with autophagy receptor SQSTM1/p62, and the TRIM27 mediated mitochondrial clustering is facilitated by SQSTM/p62. We show that phosphorylated TBK1 is recruited to the clustered mitochondria. Moreover, induced mitophagy activity is reduced in HEK293 FlpIn TRIM27 Knock Out cells, while re-introduction of EGFP-TRIM27 completely restores the mitophagy activity. Inhibition of TBK1 reduces mitophagy in HEK293 FlpIn cells and in the reconstituted EGFP-TRIM27 expressing cells, but not in HEK293 FlpIn TRIM27 Knock Out cells. Altogether, these data reveal novel roles for TRIM27 in mitophagy, facilitating mitochondrial clustering via SQSTM1/p62 and mitophagy via stabilization of phosphorylated TBK1 on mitochondria.

DOI: https://doi.org/10.1111/febs.16628
J Clin Invest. 2022 Sep 15. pii: e147120. [Epub ahead of print]132(18):

Loss of cardiomyocyte CYB5R3 impairs redox equilibrium and causes sudden cardiac death.

Nolan T Carew, Heidi M Schmidt, Shuai Yuan, Joseph C Galley, Robert Hall, Helene M Altmann, Scott A Hahn, Megan P Miller, Katherine C Wood, Bethann Gabris, Margaret C Stapleton, Sean Hartwick, Marco Fazzari, Yijen L Wu, Mohamed Trebak, Brett A Kaufman, Charles F McTiernan, Francisco J Schopfer, Placido Navas, Patrick H Thibodeau, Dennis M McNamara, Guy Salama, Adam C Straub.

  Sudden cardiac death (SCD) in patients with heart failure (HF) is allied with an imbalance in reduction and oxidation (redox) signaling in cardiomyocytes; however, the basic pathways and mechanisms governing redox homeostasis in cardiomyocytes are not fully understood. Here, we show that cytochrome b5 reductase 3 (CYB5R3), an enzyme known to regulate redox signaling in erythrocytes and vascular cells, is essential for cardiomyocyte function. Using a conditional cardiomyocyte-specific CYB5R3-knockout mouse, we discovered that deletion of CYB5R3 in male, but not female, adult cardiomyocytes causes cardiac hypertrophy, bradycardia, and SCD. The increase in SCD in CYB5R3-KO mice is associated with calcium mishandling, ventricular fibrillation, and cardiomyocyte hypertrophy. Molecular studies reveal that CYB5R3-KO hearts display decreased adenosine triphosphate (ATP), increased oxidative stress, suppressed coenzyme Q levels, and hemoprotein dysregulation. Finally, from a translational perspective, we reveal that the high-frequency missense genetic variant rs1800457, which translates into a CYB5R3 T117S partial loss-of-function protein, associates with decreased event-free survival (~20%) in Black persons with HF with reduced ejection fraction (HFrEF). Together, these studies reveal a crucial role for CYB5R3 in cardiomyocyte redox biology and identify a genetic biomarker for persons of African ancestry that may potentially increase the risk of death from HFrEF.

Keywords:  Cardiology; Heart failure; Nitric oxide; Radicals

DOI:  https://doi.org/10.1172/JCI147120
Nat Commun. 2022 Sep 12. 13(1): 5351

GCAF(TMEM251) regulates lysosome biogenesis by activating the mannose-6-phosphate pathway.

Weichao Zhang, Xi Yang, Yingxiang Li, Linchen Yu, Bokai Zhang, Jianchao Zhang, Woo Jung Cho, Varsha Venkatarangan, Liang Chen, Bala Bharathi Burugula, Sarah Bui, Yanzhuang Wang, Cunming Duan, Jacob O Kitzman, Ming Li.

The mannose-6-phosphate (M6P) biosynthetic pathway for lysosome biogenesis has been studied for decades and is considered a well-understood topic. However, whether this pathway is regulated remains an open question. In a genome-wide CRISPR/Cas9 knockout screen, we discover TMEM251 as the first regulator of the M6P modification. Deleting TMEM251 causes mistargeting of most lysosomal enzymes due to their loss of M6P modification and accumulation of numerous undigested materials. We further demonstrate that TMEM251 localizes to the Golgi and is required for the cleavage and activity of GNPT, the enzyme that catalyzes M6P modification. In zebrafish, TMEM251 deletion leads to severe developmental defects including heart edema and skeletal dysplasia, which phenocopies Mucolipidosis Type II. Our discovery provides a mechanism for the newly discovered human disease caused by TMEM251 mutations. We name TMEM251 as GNPTAB cleavage and activity factor (GCAF) and its related disease as Mucolipidosis Type V.

DOI: https://doi.org/10.1038/s41467-022-33025-1
Nature. 2022 Sep 14.

A universal coupling mechanism of respiratory complex I.

Vladyslav Kravchuk, Olga Petrova, Domen Kampjut, Anna Wojciechowska-Bason, Zara Breese, Leonid Sazanov.

Complex I is the first enzyme in the respiratory chain, which is responsible for energy production in mitochondria and bacteria1. Complex I couples the transfer of two electrons from NADH to quinone and the translocation of four protons across the membrane2, but the coupling mechanism remains contentious. Here we present cryo-electron microscopy structures of Escherichia coli complex I (EcCI) in different redox states, including catalytic turnover. EcCI exists mostly in the open state, in which the quinone cavity is exposed to the cytosol, allowing access for water molecules, which enable quinone movements. Unlike the mammalian paralogues3, EcCI can convert to the closed state only during turnover, showing that closed and open states are genuine turnover intermediates. The open-to-closed transition results in the tightly engulfed quinone cavity being connected to the central axis of the membrane arm, a source of substrate protons. Consistently, the proportion of the closed state increases with increasing pH. We propose a detailed but straightforward and robust mechanism comprising a 'domino effect' series of proton transfers and electrostatic interactions: the forward wave ('dominoes stacking') primes the pump, and the reverse wave ('dominoes falling') results in the ejection of all pumped protons from the distal subunit NuoL. This mechanism explains why protons exit exclusively from the NuoL subunit and is supported by our mutagenesis data. We contend that this is a universal coupling mechanism of complex I and related enzymes.

DOI: https://doi.org/10.1038/s41586-022-05199-7
Curr Protoc. 2022 Sep;2(9): e542

High-Throughput Neurite Outgrowth Assay Using GFP-Labeled iPSC-Derived Neurons.

Li Zhang, Shuaizhang Li, Menghang Xia.

  The potential neurotoxicity from an increasing number of drugs and untested environmental chemicals creates a need to develop reliable and efficient in vitro methods for identifying chemicals that may adversely affect the nervous system. An important process in neurodevelopment is neurite outgrowth, which can be affected by developmental neurotoxicity. Currently, neurite outgrowth assays rely mainly on staining, which requires multiple sample processing steps, particularly washing steps, that may introduce variation and limit throughput. Here, we describe a neurite outgrowth assay that uses induced pluripotent stem cell (iPSC)-derived human cortical glutamatergic neurons and/or spinal motor neurons labeled with green fluorescent protein (GFP) to test compounds in a high-content and high-throughput format. This method enables live and time-lapse imaging of GFP-labeled neurons using an assay plate that is continuously imaged at multiple times after chemical treatment. In this article, we describe how to thaw frozen GFP-labeled neurons, culture them, treat them with a compound of interest, and analyze neurite outgrowth using a high-content imaging platform. In this assay, GFP-labeled iPSC-derived human neurons represent a promising tool for identifying and prioritizing compounds with potential developmental neurotoxicity for further hazard characterization. © 2022 The Authors. Current Protocols published by Wiley Periodicals LLC. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA. Basic Protocol 1: Thawing and seeding of iPSC-derived neurons Basic Protocol 2: Compound plate preparation and treatment of neurons Basic Protocol 3: High-content imaging and analysis.

Keywords:  GFP-labeled iPSC derived human neuron; high-content imaging; neurite outgrowth; neurotoxicity

DOI:  https://doi.org/10.1002/cpz1.542