bims-mitmed Biomed News
on Mitochondrial medicine
Issue of 2023‒10‒22
nineteen papers selected by
Dario Brunetti, Fondazione IRCCS Istituto Neurologico 
  1. Developing mitochondrial base editors with diverse context compatibility and high fidelity via saturated spacer library.
  2. mtFociCounter for automated single-cell mitochondrial nucleoid quantification and reproducible foci analysis.
  3. SIRT4 is a regulator of human skeletal muscle fatty acid metabolism influencing inner and outer mitochondrial-mediated fusion.
  4. Control of mitochondrial dynamics by a fusogenic lipid.
  5. Mitochondria-lysosome-related organelles mediate mitochondrial clearance during cellular dedifferentiation.
  6. A rare, likely pathogenic variant causing Leber's hereditary optic neuropathy in three-generation females of an African-American family.
  7. Mitochondrial myopathy without extraocular muscle involvement: a unique clinicopathologic profile.
  8. Stem cells used to model a two-week-old human embryo.
  9. StarD7 deficiency switches on glycolysis and promotes mitophagy flux in C2C12 myoblasts.
  10. A PINK1 input threshold arises from positive feedback in the PINK1/Parkin mitophagy decision circuit.
  11. Anti-ageing molecule boosts fertility in ageing mice.
  12. What is fetal growth restriction and how might we know?
  13. Evaluation of Mitochondrial Function on Pyruvate Dehydrogenase Complex Deficient Patient-derived Cell Lines.
  14. MANF stimulates autophagy and restores mitochondrial homeostasis to treat autosomal dominant tubulointerstitial kidney disease in mice.
  15. Fibrocystin/Polyductin releases a C-terminal fragment that translocates into mitochondria and suppresses cystogenesis.
  16. Mitochondrial transplantation attenuates traumatic neuropathic pain, neuroinflammation, and apoptosis in rats with nerve root ligation.
  17. The SARS-CoV-2 protein ORF3c is a mitochondrial modulator of innate immunity.
  18. Human neural stem cells.
  19. Management of Friedreich's Ataxia-Associated Cardiomyopathy in Pregnancy: A Review of the Literature.
  1. Nat Commun. 2023 Oct 19. 14(1): 6625
    Developing mitochondrial base editors with diverse context compatibility and high fidelity via saturated spacer library.
    Haifeng Sun, Zhaojun Wang, Limini Shen, Yeling Feng, Lu Han, Xuezhen Qian, Runde Meng, Kangming Ji, Dong Liang, Fei Zhou, Xin Lou, Jun Zhang, Bin Shen.
      DddA-derived cytosine base editors (DdCBEs) greatly facilitated the basic and therapeutic research of mitochondrial DNA mutation diseases. Here we devise a saturated spacer library and successfully identify seven DddA homologs by performing high-throughput sequencing based screen. DddAs of Streptomyces sp. BK438 and Lachnospiraceae bacterium sunii NSJ-8 display high deaminase activity with a strong GC context preference, and DddA of Ruminococcus sp. AF17-6 is highly compatible to AC context. We also find that different split sites result in wide divergence on off-target activity and context preference of DdCBEs derived from these DddA homologs. Additionally, we demonstrate the orthogonality between DddA and DddIA, and successfully minimize the nuclear off-target editing by co-expressing corresponding nuclear-localized DddIA. The current study presents a comprehensive and unbiased strategy for screening and characterizing dsDNA cytidine deaminases, and expands the toolbox for mtDNA editing, providing additional insights for optimizing dsDNA base editors.
    DOI:  https://doi.org/10.1038/s41467-023-42359-3
  2. Nucleic Acids Res. 2023 Oct 18. pii: gkad864. [Epub ahead of print]
    mtFociCounter for automated single-cell mitochondrial nucleoid quantification and reproducible foci analysis.
    Timo Rey, Luis Carlos Tábara, Julien Prudent, Michal Minczuk.
      Mitochondrial DNA (mtDNA) encodes the core subunits for OXPHOS, essential in near-all eukaryotes. Packed into distinct foci (nucleoids) inside mitochondria, the number of mtDNA copies differs between cell-types and is affected in several human diseases. Currently, common protocols estimate per-cell mtDNA-molecule numbers by sequencing or qPCR from bulk samples. However, this does not allow insight into cell-to-cell heterogeneity and can mask phenotypical sub-populations. Here, we present mtFociCounter, a single-cell image analysis tool for reproducible quantification of nucleoids and other foci. mtFociCounter is a light-weight, open-source freeware and overcomes current limitations to reproducible single-cell analysis of mitochondrial foci. We demonstrate its use by analysing 2165 single fibroblasts, and observe a large cell-to-cell heterogeneity in nucleoid numbers. In addition, mtFociCounter quantifies mitochondrial content and our results show good correlation (R = 0.90) between nucleoid number and mitochondrial area, and we find nucleoid density is less variable than nucleoid numbers in wild-type cells. Finally, we demonstrate mtFociCounter readily detects differences in foci-numbers upon sample treatment, and applies to Mitochondrial RNA Granules and superresolution microscopy. mtFociCounter provides a versatile solution to reproducibly quantify cellular foci in single cells and our results highlight the importance of accounting for cell-to-cell variance and mitochondrial context in mitochondrial foci analysis.
    DOI:  https://doi.org/10.1093/nar/gkad864
  3. Cell Signal. 2023 Oct 17. pii: S0898-6568(23)00346-7. [Epub ahead of print] 110931
    SIRT4 is a regulator of human skeletal muscle fatty acid metabolism influencing inner and outer mitochondrial-mediated fusion.
    John Noone, Keith D Rochfort, Finbarr O'Sullivan, Donal J O'Gorman.
      OBJECTIVE: The mitochondrial phenotype, governed by the balance of fusion-fission, is a key determinant of energy metabolism. The inner and outer mitochondrial membrane (IMM) fusion proteins optic atrophy 1 (OPA1) and Mitofusin 1 and 2 (Mfn1/2) play an important role in this process. Recent evidence also shows that Sirtuin 4 (SIRT4), located within the mitochondria, is involved in the regulation of fatty acid oxidation. The purpose of this study was to determine if SIRT4 expression regulates inner and outer mitochondrial-mediated fusion and substrate utilization within differentiated human skeletal muscle cells (HSkMC).MATERIAL AND METHODS: SIRT4 expression was knocked down using small interfering RNA (siRNA) transfection in differentiated HSkMC. Following knockdown, mitochondrial respiration was determined by high-resolution respirometry (HRR) using the Oroboros Oxygraph O2k. Live cell confocal microscopy, quantified using the Mitochondrial Network Analysis (MiNA) toolset, was used to examine mitochondrial morphological change. This was further examined through the measurement of key metabolic and mitochondrial morphological regulators (mRNA and protein) induced by knockdown.
    RESULTS: SIRT4 knockdown resulted in a significant decrease in LEAK respiration, potentially explained by a decrease in ANT1 protein expression. Knockdown further increased oxidative phosphorylation and protein expression of key regulators of fatty acid metabolism. Quantitative analysis of live confocal imaging of fluorescently labelled mitochondria following SIRT4 knockdown supported the role SIRT4 plays in the regulation of mitochondrial morphology, as emphasized by an increase in mitochondrial network branches and junctions. Measurement of key regulators of mitochondrial dynamics illustrated a significant increase in mitochondrial fusion proteins Mfn1, OPA1 respectively, indicative of an increase in mitochondrial size.
    CONCLUSIONS: This study provides evidence of a direct relationship between the mitochondrial phenotype and substrate oxidation in HSkMC. We identify SIRT4 as a key protagonist of energy metabolism via its regulation of IMM and OMM fusion proteins, OPA1 and Mfn1. SIRT4 knockdown increases mitochondrial capacity to oxidize fatty acids, decreasing LEAK respiration and further increasing mitochondrial elongation via its regulation of mitochondrial fusion.
    Keywords:  Metabolism; Mitochondrial dynamics; Mitochondrial function; OPA1; Sirtuin; Skeletal muscle
    DOI:  https://doi.org/10.1016/j.cellsig.2023.110931
  4. Trends Cell Biol. 2023 Oct 17. pii: S0962-8924(23)00210-6. [Epub ahead of print]
    Control of mitochondrial dynamics by a fusogenic lipid.
    Zheng Yang, David C Chan.
      Mitochondrial fusion enables cooperation between the mitochondrial population and is critical for mitochondrial function. Phosphatidic acid (PA) on the mitochondrial surface has a key role in mitochondrial fusion. A recent study by Su et al. shows that the nucleoside diphosphate (NDP) kinase NME3 recognizes PA and mediates its effects on mitochondrial dynamics.
    Keywords:  membrane fusion; mitochondria; organelle; phospholipid
    DOI:  https://doi.org/10.1016/j.tcb.2023.10.006
  5. Cell Rep. 2023 Oct 19. pii: S2211-1247(23)01303-7. [Epub ahead of print]42(10): 113291
    Mitochondria-lysosome-related organelles mediate mitochondrial clearance during cellular dedifferentiation.
    Xiaowen Ma, Sharon Manley, Hui Qian, Yuan Li, Chen Zhang, Kevin Li, Benjamin Ding, Fengli Guo, Allen Chen, Xing Zhang, Meilian Liu, Meihua Hao, Benjamin Kugler, E Matthew Morris, John Thyfault, Ling Yang, Hiromi Sesaki, Hong-Min Ni, Heidi McBride, Wen-Xing Ding.
      Dysfunctional mitochondria are removed via multiple pathways, such as mitophagy, a selective autophagy process. Here, we identify an intracellular hybrid mitochondria-lysosome organelle (termed the mitochondria-lysosome-related organelle [MLRO]), which regulates mitochondrial homeostasis independent of canonical mitophagy during hepatocyte dedifferentiation. The MLRO is an electron-dense organelle that has either a single or double membrane with both mitochondria and lysosome markers. Mechanistically, the MLRO is likely formed from the fusion of mitochondria-derived vesicles (MDVs) with lysosomes through a PARKIN-, ATG5-, and DRP1-independent process, which is negatively regulated by transcription factor EB (TFEB) and associated with mitochondrial protein degradation and hepatocyte dedifferentiation. The MLRO, which is galectin-3 positive, is reminiscent of damaged lysosome and could be cleared by overexpression of TFEB, resulting in attenuation of hepatocyte dedifferentiation. Together, results from this study suggest that the MLRO may act as an alternative mechanism for mitochondrial quality control independent of canonical autophagy/mitophagy involved in cell dedifferentiation.
    Keywords:  ATG5; CP: Cell biology; DRP1; autophagy; hepatocytes; lysosome; mitophagy
    DOI:  https://doi.org/10.1016/j.celrep.2023.113291
  6. Am J Ophthalmol Case Rep. 2023 Dec;32 101936
    A rare, likely pathogenic variant causing Leber's hereditary optic neuropathy in three-generation females of an African-American family.
    Yanjun Chen, Elizabeth R Kellom.
      Purpose: We report a rare, likely pathogenic variant gene causing Leber's hereditary optic neuropathy (LHON) in three-generation female members of an African-American family.Observations: The granddaughter and mother presented with a subacute, painless visual loss in both eyes at age 10 and 42 years to legal blindness. The maternal grandmother presented with a gradual onset of moderate visual loss at age 60. The mother and grandmother reported a history of bariatric surgery and subsequent vitamin deficiencies. All three patients shared similar Optical Coherent Tomography (OCT) findings of profound thinning of ganglion cell complex (GCC) and relatively preserved peripapillary retinal nerve fiber layer thickness (pRNFL). Nuclear and mitochondrial DNA sequencing identified a 14596A > T likely pathogenic variant, p.(Ile26Met), in the MT-ND6 gene, with 100% homoplasmy in the granddaughter and mother and 65% heteroplasmy in the grandmother. The mother and grandmother were treated with idebenone in addition to vitamin supplements, with a slight improvement in their vision.
    Conclusions and Importance: Our patients' presentation stresses the importance of including LHON in the differential diagnosis in females presenting with unexplained bilateral, painless, severe visual loss. The OCT finding of profound GCC thinning with relatively preserved pRNFL thickness can be a red flag for LHON. A collaboration with genetic specialists to utilize expanded gene sequencing may greatly enhance our ability to identify rare pathogenic variants.
    Keywords:  14596A>T variant; Females; Leber's hereditary optic neuropathy (LHON); Nutritional deficiency
    DOI:  https://doi.org/10.1016/j.ajoc.2023.101936
  7. J Neurol. 2023 Oct 17.
    Mitochondrial myopathy without extraocular muscle involvement: a unique clinicopathologic profile.
    Yan Lin, Jiayin Wang, Hong Ren, Xiaotian Ma, Wei Wang, Ying Zhao, Zhihong Xu, Shuangwu Liu, Wenqing Wang, Xuebi Xu, Bin Wang, Dandan Zhao, Dongdong Wang, Wei Li, Fuchen Liu, Yuying Zhao, Jianqiang Lu, Chuanzhu Yan, Kunqian Ji.
      OBJECTIVE: Mitochondrial myopathy without extraocular muscles involvement (MiMy) represents a distinct form of mitochondrial disorder predominantly affecting proximal/distal or axial muscles, with its phenotypic, genotypic features, and long-term prognosis poorly understood.METHODS: A cross-sectional study conducted at a national diagnostic center for mitochondrial disease involved 47 MiMy patients, from a cohort of 643 mitochondrial disease cases followed up at Qilu Hospital from January 1, 2000, to January 1, 2021. We compared the clinical, pathological, and genetic features of MiMy to progressive external ophthalmoplegia (PEO) and mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS) patients.
    RESULTS: MiMy patients demonstrated a more pronounced muscle involvement syndrome, with lower 6MWT scores, higher FSS, and lower BMI compared to PEO and MELAS patients. Serum levels of creatinine kinase (CK), lactate, and growth and differentiation factor 15 (GDF15) were substantially elevated in MiMy patients. Nearly a third (31.9%) displayed signs of subclinical peripheral neuropathy, mostly axonal neuropathy. Muscle biopsies revealed that cytochrome c oxidase strong (COX-s) ragged-red fibers (RRFs) were a typical pathological feature in MiMy patients. Genetic analysis predominantly revealed mtDNA point pathogenic variants (59.6%) and less frequently single (12.8%) or multiple (4.2%) mtDNA deletions. During the follow-up, a majority (76.1%) of MiMy patients experienced stabilization or improvement after therapeutic intervention.
    CONCLUSIONS: This study provides a comprehensive profile of MiMy through a large patient cohort, elucidating its unique clinical, genetic, and pathological features. These findings offer significant insights into the diagnostic and therapeutic management of MiMy, ultimately aiming to ameliorate patient outcomes and enhance the quality of life.
    Keywords:  Clinicopathologic features; MELAS; MiMy; Mitochondrial disorders; PEO
    DOI:  https://doi.org/10.1007/s00415-023-12005-5
  8. Nature. 2023 Oct;622(7983): 469-470
    Stem cells used to model a two-week-old human embryo.
    Naomi Moris.
      
    Keywords:  Developmental biology; Stem cells
    DOI:  https://doi.org/10.1038/d41586-023-03150-y
  9. FEBS J. 2023 Oct 16.
    StarD7 deficiency switches on glycolysis and promotes mitophagy flux in C2C12 myoblasts.
    María L Rojas, Juan Pablo Muñoz, Jésica Flores-Martín, Paula Sànchez-Fernàndez-de-Landa, Mariano Cruz Del Puerto, Susana Genti-Raimondi, Antonio Zorzano.
      StarD7 is a member of the START protein family required for phosphatidylcholine delivery to the mitochondria, thus key to maintain mitochondrial structure. Its deficiency has been associated with an impairment of cellular processes, such as proliferation and migration, and it has also been reported that it is needed in myogenic differentiation. Here, we show that StarD7 deficiency in C2C12 muscle cells results in the accumulation of abnormal mitochondria, a reduced number of mitochondria per cell area and increased glycolysis. In addition, StarD7-deficient cells undergo an increase in mitochondria-ER contact sites, reduced connexin 43 expression, and disturbances in lipid handling, evidenced by lipid droplet accumulation and decreased levels in phosphatidylserine synthase 1 and 2 expression. Interestingly, StarD7-deficient cells showed alterations in mitophagy markers. We observed accumulation of LC3B-II and BNIP3 proteins in mitochondria-enriched fractions and accumulation of autophagolysosomal and lysosomal vesicles in StarD7-deficient cells. Furthermore, live-cell imaging experiments of StarD7 knockdown cells expressing mitochondria-targeted mKeima indicated an enhanced mitochondria delivery into lysosomes. Importantly, StarD7 reconstitution in StarD7-deficient cells restores LC3B-II expression in mitochondria-enriched fractions at similar levels to those observed in control cells. Collectively, these findings suggest that StarD7-deficient C2C12 myoblasts are associated with altered cristae structure, disturbances in neutral lipid accumulation, glucose metabolism, and increased mitophagy flux. The alterations mentioned above allow for the maintenance of mitochondrial function.
    Keywords:  StarD7; cristae morphology; lipid droplet; mitophagy
    DOI:  https://doi.org/10.1111/febs.16979
  10. Cell Rep. 2023 Oct 17. pii: S2211-1247(23)01272-X. [Epub ahead of print]42(10): 113260
    A PINK1 input threshold arises from positive feedback in the PINK1/Parkin mitophagy decision circuit.
    Christopher S Waters, Sigurd B Angenent, Steven J Altschuler, Lani F Wu.
      Mechanisms that prevent accidental activation of the PINK1/Parkin mitophagy circuit on healthy mitochondria are poorly understood. On the surface of damaged mitochondria, PINK1 accumulates and acts as the input signal to a positive feedback loop of Parkin recruitment, which in turn promotes mitochondrial degradation via mitophagy. However, PINK1 is also present on healthy mitochondria, where it could errantly recruit Parkin and thereby activate this positive feedback loop. Here, we explore emergent properties of the PINK1/Parkin circuit by quantifying the relationship between mitochondrial PINK1 concentrations and Parkin recruitment dynamics. We find that Parkin is recruited to mitochondria only if PINK1 levels exceed a threshold and then only after a delay that is inversely proportional to PINK1 levels. Furthermore, these two regulatory properties arise from the input-coupled positive feedback topology of the PINK1/Parkin circuit. These results outline an intrinsic mechanism by which the PINK1/Parkin circuit can avoid errant activation on healthy mitochondria.
    Keywords:  CP: Molecular biology; PINK1; Parkin; circuit; delay; mathematical model; mitophagy decision; quantitative microscopy; synthetic biology; systems biology; threshold
    DOI:  https://doi.org/10.1016/j.celrep.2023.113260
  11. Nature. 2023 Oct 16.
    Anti-ageing molecule boosts fertility in ageing mice.
    Gemma Conroy.
      
    Keywords:  Ageing; Cell biology; Molecular biology
    DOI:  https://doi.org/10.1038/d41586-023-03224-x
  12. J Physiol. 2023 Oct 17.
    What is fetal growth restriction and how might we know?
    Steven J Korzeniewski.
      
    Keywords:  causal inference; developmental programming; periconception; perinatal; pregnancy
    DOI:  https://doi.org/10.1113/JP285445
  13. Endocr Metab Immune Disord Drug Targets. 2023 Oct 11.
    Evaluation of Mitochondrial Function on Pyruvate Dehydrogenase Complex Deficient Patient-derived Cell Lines.
    Hana Pavlú-Pereira, Cristina Florindo, Filipa Carvalho, Isabel Tavares de Almeida, Joao Vicente, Vanessa Morais, Isabel Rivera.
      INTRODUCTION: Pyruvate Dehydrogenase Complex (PDC) is a pivotal gatekeeper between cytosolic glycolysis and mitochondrial oxidative phosphorylation, playing important role in aerobic energy metabolism. Most PDC deficiency, cases being caused by mutations in PDHA1 encoding the α subunit of the rate-limiting E1 enzyme, which is characterized by abnormal phenotypes caused by energy deprivation at peripheral/central nervous systems and muscular tissues. This study aims to evaluate the potential therapeutic effect of arginine and thiamine in ameliorating mitochondrial function in patient-derived cultured cells.MATERIALS AND METHODS: PDC-deficient cell lines, carrying three different PDHA1 variants, were cultured in the absence and presence of arginine and/or thiamine at therapeutical levels, 4 mM and 100 μM, respectively. Mitochondrial bioenergetics profile was evaluated using the Seahorse extracellular flux analyzer.
    RESULTS: In physiological conditions, control cells presented standard values for all parameters evaluating the mitochondrial function, no differences being observed after supplementation of culture medium with therapeutic levels of arginine and/or thiamine. However, PDC-PDHA1 deficient cell lines consumed less oxygen than the control cells, but arginine and thiamine supplementation increased the basal respiration for values similar or higher than the control cell line. Moreover, arginine and thiamine treatment highlighted an inefficient oxidative phosphorylation carried out by PDC-deficient cell lines. Finally, this treatment showed an increased oxygen consumption by enzymes other than those in the respiratory chain, thus proving the dependence of these mutant cell lines on cytosolic sources for ATP production, namely glycolysis.
    CONCLUSIONS: This study showed that arginine and thiamine, at therapeutical levels, increase the basal oxygen consumption rate of PDC-deficient cell lines, as well as their ATP-linked respiration. This parameter measures the capacity of the cell to meet its energetic demands and, therefore, its increase reveals a higher electron flow through the respiratory chain, which is coupled to elevated oxidative phosphorylation, thus indicating an overall increased robustness in mitochondrial- related bioenergetics.
    Keywords:  arginine; energy metabolism; mitochondrial bioenergetics; pyruvate dehydrogenase complex; pyruvate dehydrogenase complex deficiency; thiamine
    DOI:  https://doi.org/10.2174/0118715303280072231004082458
  14. Nat Commun. 2023 Oct 14. 14(1): 6493
    MANF stimulates autophagy and restores mitochondrial homeostasis to treat autosomal dominant tubulointerstitial kidney disease in mice.
    Yeawon Kim, Chuang Li, Chenjian Gu, Yili Fang, Eric Tycksen, Anuradhika Puri, Terri A Pietka, Jothilingam Sivapackiam, Kendrah Kidd, Sun-Ji Park, Bryce G Johnson, Stanislav Kmoch, Jeremy S Duffield, Anthony J Bleyer, Meredith E Jackrel, Fumihiko Urano, Vijay Sharma, Maria Lindahl, Ying Maggie Chen.
      Misfolded protein aggregates may cause toxic proteinopathy, including autosomal dominant tubulointerstitial kidney disease due to uromodulin mutations (ADTKD-UMOD), a leading hereditary kidney disease. There are no targeted therapies. In our generated mouse model recapitulating human ADTKD-UMOD carrying a leading UMOD mutation, we show that autophagy/mitophagy and mitochondrial biogenesis are impaired, leading to cGAS-STING activation and tubular injury. Moreover, we demonstrate that inducible tubular overexpression of mesencephalic astrocyte-derived neurotrophic factor (MANF), a secreted endoplasmic reticulum protein, after the onset of disease stimulates autophagy/mitophagy, clears mutant UMOD, and promotes mitochondrial biogenesis through p-AMPK enhancement, thus protecting kidney function in our ADTKD mouse model. Conversely, genetic ablation of MANF in the mutant thick ascending limb tubular cells worsens autophagy suppression and kidney fibrosis. Together, we have discovered MANF as a biotherapeutic protein and elucidated previously unknown mechanisms of MANF in the regulation of organelle homeostasis, which may have broad therapeutic applications to treat various proteinopathies.
    DOI:  https://doi.org/10.1038/s41467-023-42154-0
  15. Nat Commun. 2023 Oct 16. 14(1): 6513
    Fibrocystin/Polyductin releases a C-terminal fragment that translocates into mitochondria and suppresses cystogenesis.
    Rebecca V Walker, Qin Yao, Hangxue Xu, Anthony Maranto, Kristen F Swaney, Sreekumar Ramachandran, Rong Li, Laura Cassina, Brian M Polster, Patricia Outeda, Alessandra Boletta, Terry Watnick, Feng Qian.
      Fibrocystin/Polyductin (FPC), encoded by PKHD1, is associated with autosomal recessive polycystic kidney disease (ARPKD), yet its precise role in cystogenesis remains unclear. Here we show that FPC undergoes complex proteolytic processing in developing kidneys, generating three soluble C-terminal fragments (ICDs). Notably, ICD15, contains a novel mitochondrial targeting sequence at its N-terminus, facilitating its translocation into mitochondria. This enhances mitochondrial respiration in renal epithelial cells, partially restoring impaired mitochondrial function caused by FPC loss. FPC inactivation leads to abnormal ultrastructural morphology of mitochondria in kidney tubules without cyst formation. Moreover, FPC inactivation significantly exacerbates renal cystogenesis and triggers severe pancreatic cystogenesis in a Pkd1 mouse mutant Pkd1V/V in which cleavage of Pkd1-encoded Polycystin-1 at the GPCR Proteolysis Site is blocked. Deleting ICD15 enhances renal cystogenesis without inducing pancreatic cysts in Pkd1V/V mice. These findings reveal a direct link between FPC and a mitochondrial pathway through ICD15 cleavage, crucial for cystogenesis mechanisms.
    DOI:  https://doi.org/10.1038/s41467-023-42196-4
  16. Mol Pain. 2023 Oct 16. 17448069231210423
    Mitochondrial transplantation attenuates traumatic neuropathic pain, neuroinflammation, and apoptosis in rats with nerve root ligation.
    Chi-Chen Huang, Hsin-Yi Chiu, Po-Hsuan Lee, Shih-Yuan Fang, Ming-Wei Lin, Hui-Fang Chen, Jung-Shun Lee.
      Traumatic neuropathic pain (TNP) is caused by traumatic damage to the somatosensory system and induces the presentation of allodynia and hyperalgesia. Mitochondrial dysfunction, neuroinflammation, and apoptosis are hallmarks in the pathogenesis of TNP. Recently, mitochondria-based therapy has emerged as a potential therapeutic intervention for diseases related to mitochondrial dysfunction. However, the therapeutic effectiveness of mitochondrial transplantation (MT) on TNP has rarely been investigated. Here, we validated the efficacy of MT in treating TNP. Both in vivo and in vitro TNP models by conducting an L5 spinal nerve ligation in rats and exposing the primary dorsal root ganglion (DRG) neurons to capsaicin, respectively, were applied in this study. The MT was operated by administrating 100 µg of soleus-derived allogeneic mitochondria into the ipsilateral L5 DRG in vivo and the culture medium in vitro. Results showed that the viable transplanted mitochondria migrated into the rats' spinal cord and sciatic nerve. MT alleviated the nerve ligation-induced mechanical and thermal pain hypersensitivity. The nerve ligation-induced glial activation and the expression of pro-inflammatory cytokines and apoptotic markers in the spinal cord were also repressed by MT. Consistently, exogenous mitochondria reversed the capsaicin-induced reduction of mitochondrial membrane potential and expression of pro-inflammatory cytokines and apoptotic markers in the primary DRG neurons in vitro. Our findings suggest that MT mitigates the spinal nerve ligation-induced apoptosis and neuroinflammation, potentially playing a role in providing neuroprotection against TNP.
    Keywords:  Apoptosis; Mitochondrial dysfunction; Mitochondrial transplantation; Neuroinflammation; Traumatic neuropathic pain
    DOI:  https://doi.org/10.1177/17448069231210423
  17. iScience. 2023 Nov 17. 26(11): 108080
    The SARS-CoV-2 protein ORF3c is a mitochondrial modulator of innate immunity.
    Hazel Stewart, Yongxu Lu, Sarah O'Keefe, Anusha Valpadashi, Luis Daniel Cruz-Zaragoza, Hendrik A Michel, Samantha K Nguyen, George W Carnell, Nina Lukhovitskaya, Rachel Milligan, Yasmin Adewusi, Irwin Jungreis, Valeria Lulla, David A Matthews, Stephen High, Peter Rehling, Edward Emmott, Jonathan L Heeney, Andrew D Davidson, James R Edgar, Geoffrey L Smith, Andrew E Firth.
      The SARS-CoV-2 genome encodes a multitude of accessory proteins. Using comparative genomic approaches, an additional accessory protein, ORF3c, has been predicted to be encoded within the ORF3a sgmRNA. Expression of ORF3c during infection has been confirmed independently by ribosome profiling. Despite ORF3c also being present in the 2002-2003 SARS-CoV, its function has remained unexplored. Here we show that ORF3c localizes to mitochondria, where it inhibits innate immunity by restricting IFN-β production, but not NF-κB activation or JAK-STAT signaling downstream of type I IFN stimulation. We find that ORF3c is inhibitory after stimulation with cytoplasmic RNA helicases RIG-I or MDA5 or adaptor protein MAVS, but not after TRIF, TBK1 or phospho-IRF3 stimulation. ORF3c co-immunoprecipitates with the antiviral proteins MAVS and PGAM5 and induces MAVS cleavage by caspase-3. Together, these data provide insight into an uncharacterized mechanism of innate immune evasion by this important human pathogen.
    Keywords:  Immunology; Microbiology; Molecular biology; Proteomics
    DOI:  https://doi.org/10.1016/j.isci.2023.108080
  18. Cell Prolif. 2023 Oct 18. e13564
    Human neural stem cells.
    Yu-Kai Wang, Juan Yu, Ting-Ting Zhang, Ai-Jin Ma, Jie Hao, Yue-Jun Chen, Chang-Mei Liu, Yan Liu, Chang-Lin Wang, Pei-Jun Zhai, Andy Peng Xiang, Tian-Qing Li, Tie-Shan Tang, Hong Chen, Xin-Jie Bao, Yan-Lin Wang, Wen-Yan He, Jing Fan, Zhao-Qian Teng, Liu Wang, Jia-Xi Zhou, Bo-Qiang Fu, Yu Vincent Fu, Lin Feng, Jia-Ni Cao, Ling-Min Liang, Lei Wang, Qi Zhou, Yu Zhang, Bao-Yang Hu, Tong-Biao Zhao.
      'Human neural stem cells' jointly drafted and agreed upon by experts from the Chinese Society for Stem Cell Research, is the first guideline for human neural stem cells (hNSCs) in China. This standard specifies the technical requirements, test methods, test regulations, instructions for use, labelling requirements, packaging requirements, storage requirements, transportation requirements and waste disposal requirements for hNSCs, which is applicable to the quality control for hNSCs. It was originally released by the China Society for Cell Biology on 30 August 2022. We hope that publication of the guideline will facilitate institutional establishment, acceptance and execution of proper protocols, and accelerate the international standardization of hNSCs for clinical development and therapeutic applications.
    DOI:  https://doi.org/10.1111/cpr.13564
  19. Am J Cardiol. 2023 Oct 12. pii: S0002-9149(23)01153-0. [Epub ahead of print]
    Management of Friedreich's Ataxia-Associated Cardiomyopathy in Pregnancy: A Review of the Literature.
    Ashleigh N Peterson, Leigh C Hickerson, E Rebecca Pschirrer, Lynsy B Friend, Cynthia C Taub.
      A major manifestation of Friedreich's ataxia (FRDA) is cardiomyopathy, caused by mitochondrial proliferation in myocytes. As lifespan for people with FRDA improves with better treatment modalities, more people are becoming pregnant, meaning that more medical providers must know how to care for this population. This paper provides a review of the literature on multi-disciplinary management of pregnant patients with FRDA and cardiomyopathy from pre-conception through lactation. A cardio-obstetrics team including cardiology, anesthesiology, and obstetrics should be involved for this entire period. All patients should be counseled on pregnancy risk, using elements of existing stratification systems, and contraception should be discussed, highlighting the safety of intrauterine devices (IUDs). EKG should be obtained at baseline and each trimester, looking for atrial arrhythmias and ST segment changes, as should transthoracic echocardiogram (TTE), with a focus on left ventricular ejection fraction (LVEF) - which is typically normal in FRDA cardiomyopathy - as well as relative wall thickness (RWT), and global longitudinal strain - which tend to decrease as cardiomyopathy progresses. Brain natriuretic peptide (BNP) is also a helpful marker to detect adverse events. If heart failure develops, it should be treated like any other etiology of heart failure during pregnancy. Atrial arrhythmias should be treated with beta blockers or electrical cardioversion and anticoagulation as necessary. Most patients with FRDA can deliver vaginally, and neuraxial analgesia is recommended during labor due to the risks associated with general anesthesia. Breastfeeding is encouraged, even for those taking cardiac medications.
    Keywords:  Friedreich's ataxia; cardio-obstetrics; cardiomyopathy; pregnancy
    DOI:  https://doi.org/10.1016/j.amjcard.2023.10.019
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