bims-symami 2023-04-16 papers

bims-symami

Biomed News

on Symptom management in mitochondrial disease

Issue of 2023–04–16
seven papers selected by
The Lily Foundation

Mitochondrial Inheritance Following Nuclear Transfer: From Cloned Animals to Patients with Mitochondrial Disease.
Phenotyping mtDNA-related diseases in childhood: a cohort study of 150 patients.
Diagnosing mitochondrial, neurogastrointestinal leukoencephalopathy requires mutations in TYMP1, POLG1, LIG1, or RRM2B.
The Beneficial Effect of Mitochondrial Transfer Therapy in 5XFAD Mice via Liver-Serum-Brain Response.
Low Protein Programming Causes Increased Mitochondrial Fusion and Decreased Oxygen Consumption in the Hepatocytes of Female Rats.
Comparison of different gene-therapy methods to treat Leber hereditary optic neuropathy in a mouse model.
Possible frequent multiple mitochondrial DNA copies in a single nucleoid in HeLa cells.

Methods Mol Biol. 2023 ;2647 83-104

Mitochondrial Inheritance Following Nuclear Transfer: From Cloned Animals to Patients with Mitochondrial Disease.

Jörg P Burgstaller, Marcos R Chiaratti.

  Mitochondria are indispensable power plants of eukaryotic cells that also act as a major biochemical hub. As such, mitochondrial dysfunction, which can originate from mutations in the mitochondrial genome (mtDNA), may impair organism fitness and lead to severe diseases in humans. MtDNA is a multi-copy, highly polymorphic genome that is uniparentally transmitted through the maternal line. Several mechanisms act in the germline to counteract heteroplasmy (i.e., coexistence of two or more mtDNA variants) and prevent expansion of mtDNA mutations. However, reproductive biotechnologies such as cloning by nuclear transfer can disrupt mtDNA inheritance, resulting in new genetic combinations that may be unstable and have physiological consequences. Here, we review the current understanding of mitochondrial inheritance, with emphasis on its pattern in animals and human embryos generated by nuclear transfer.

Keywords:  Cloning; Embryo; Heteroplasmy; MRT; Mitochondria; Nuclear transplantation; Oocyte; SCNT; mtDNA

DOI:  https://doi.org/10.1007/978-1-0716-3064-8_4
Eur J Neurol. 2023 Apr 10.

Phenotyping mtDNA-related diseases in childhood: a cohort study of 150 patients.

Anna Ardissone, Giulia Ferrera, Costanza Lamperti, Valeria Tiranti, Daniele Ghezzi, Isabella Moroni, Eleonora Lamantea.

   BACKGROUND: Mitochondrial diseases (MDs) are heterogeneous disorders caused by mutations in nuclear DNA (nDNA) or mitochondrial DNA (mtDNA) associated with specific syndromes. However, especially in childhood, patients often display heterogeneity. Several reports about the biochemical and molecular profiles in children have been published, but studies tend to not differentiate between mtDNA and nDNA associated diseases and focus is often on a specific phenotype. Thus, large cohort studies specifically focusing on mtDNA defects in the pediatric population are lacking.
METHODS: We reviewed the clinical, metabolic, biochemical, and neuroimaging data of 150 patients with MDs due to mtDNA alterations collected at our Neurological Institute over the past 20 years.
RESULTS: MtDNA impairment is less frequent than nDNA in pediatric MDs. Ocular involvement is extremely frequent in our cohort, as is classical Leber Hereditary Optic Neuropathy, especially with onset before 12 years of age. Extra neurological manifestations and isolated myopathy appear to be rare, unlike adult phenotypes. Deep gray matter involvement, early disease onset and specific phenotypes, such as Pearson syndrome and Leigh syndrome, represent unfavorable prognostic factors. Phenotypes related to single large scale mtDNA deletions appear to be very frequent in the pediatric population. Furthermore, we report for the first time a mtDNA pathogenic variant associated with cavitating leukodystrophy.
CONCLUSIONS: We report on a large cohort of pediatric patients with mtDNA defects, adding new data on the phenotypical characterization of mtDNA defects and possible suggestions for the diagnostic workup and therapeutic approach.

Keywords:  mitochondrial DNA; mitochondrial disorder; pediatric; phenotypes

DOI:  https://doi.org/10.1111/ene.15814
J Med Case Rep. 2023 Apr 14. 17(1): 162

Diagnosing mitochondrial, neurogastrointestinal leukoencephalopathy requires mutations in TYMP1, POLG1, LIG1, or RRM2B.

Josef Finsterer.



Keywords:  Lactic acidosis; MNGIE; Mitochondrial disorder; TYMP1; Vomiting; White matter lesions

DOI:  https://doi.org/10.1186/s13256-023-03916-y
Cells. 2023 Mar 24. pii: 1006. [Epub ahead of print]12(7):

The Beneficial Effect of Mitochondrial Transfer Therapy in 5XFAD Mice via Liver-Serum-Brain Response.

Sahar Sweetat, Keren Nitzan, Nir Suissa, Yael Haimovich, Michal Lichtenstein, Samar Zabit, Sandrine Benhamron, Karameh Akarieh, Kumudesh Mishra, Dinorah Barasch, Ann Saada, Tamar Ziv, Or Kakhlon, Haya Lorberboum-Galski, Hanna Rosenmann.

  We recently reported the benefit of the IV transferring of active exogenous mitochondria in a short-term pharmacological AD (Alzheimer's disease) model. We have now explored the efficacy of mitochondrial transfer in 5XFAD transgenic mice, aiming to explore the underlying mechanism by which the IV-injected mitochondria affect the diseased brain. Mitochondrial transfer in 5XFAD ameliorated cognitive impairment, amyloid burden, and mitochondrial dysfunction. Exogenously injected mitochondria were detected in the liver but not in the brain. We detected alterations in brain proteome, implicating synapse-related processes, ubiquitination/proteasome-related processes, phagocytosis, and mitochondria-related factors, which may lead to the amelioration of disease. These changes were accompanied by proteome/metabolome alterations in the liver, including pathways of glucose, glutathione, amino acids, biogenic amines, and sphingolipids. Altered liver metabolites were also detected in the serum of the treated mice, particularly metabolites that are known to affect neurodegenerative processes, such as carnosine, putrescine, C24:1-OH sphingomyelin, and amino acids, which serve as neurotransmitters or their precursors. Our results suggest that the beneficial effect of mitochondrial transfer in the 5XFAD mice is mediated by metabolic signaling from the liver via the serum to the brain, where it induces protective effects. The high efficacy of the mitochondrial transfer may offer a novel AD therapy.

Keywords:  5XFAD; Alzheimer’s disease; amyloid; cognition; mitochondria; mitochondrial transfer

DOI:  https://doi.org/10.3390/cells12071006
Nutrients. 2023 Mar 24. pii: 1568. [Epub ahead of print]15(7):

Low Protein Programming Causes Increased Mitochondrial Fusion and Decreased Oxygen Consumption in the Hepatocytes of Female Rats.

Vipin A Vidyadharan, Chellakkan S Blesson, Daren Tanchico, Ancizar Betancourt, Craig Smith, Chandra Yallampalli.

  The liver is one of the major organs involved in the regulation of glucose and lipid homeostasis. The effectiveness of metabolic activity in hepatocytes is determined by the quality and quantity of its mitochondria. Mitochondrial function is complex, and they act via various dynamic networks, which rapidly adapt to changes in the cellular milieu. Our present study aims to investigate the effects of low protein programming on the structure and function of mitochondria in the hepatocytes of adult females. Pregnant rats were fed with a control or isocaloric low-protein diet from gestational day 4 until delivery. A normal laboratory chow was given to all dams after delivery and to pups after weaning. The rats were euthanized at 4 months of age and the livers were collected from female offspring for investigating the mitochondrial structure, mtDNA copy number, mRNA, and proteins expression of genes associated with mitochondrial function. Primary hepatocytes were isolated and used for the analysis of the mitochondrial bioenergetics profiles. The mitochondrial ultrastructure showed that the in utero low-protein diet exposure led to increased mitochondrial fusion. Accordingly, there was an increase in the mRNA and protein levels of the mitochondrial fusion gene Opa1 and mitochondrial biogenesis genes Pgc1a and Essra, but Fis1, a fission gene, was downregulated. Low protein programming also impaired the mitochondrial function of the hepatocytes with a decrease in basal respiration ATP-linked respiration and proton leak. In summary, the present study suggests that the hepatic mitochondrial dysfunction induced by an in utero low protein diet might be a potential mechanism linking glucose intolerance and insulin resistance in adult offspring.

Keywords:  developmental programming; insulin resistance; lean T2D; mitochondria dysfunction; mitochondrial dynamics

DOI:  https://doi.org/10.3390/nu15071568
Front Neurosci. 2023 ;17 1119724

Comparison of different gene-therapy methods to treat Leber hereditary optic neuropathy in a mouse model.

Sindhu Velmurugan, Tsung-Han Chou, Jeremy D Eastwood, Vittorio Porciatti, Yuan Liu, William W Hauswirth, John Guy, Hong Yu.

   Introduction: Therapies for Leber hereditary optic neuropathy (LHON), in common with all disorders caused by mutated mitochondrial DNA, are inadequate. We have developed two gene therapy strategies for the disease: mitochondrial-targeted and allotopic expressed and compared them in a mouse model of LHON.
Methods: A LHON mouse model was generated by intravitreal injection of a mitochondrialtargeted Adeno-associated virus (AAV) carrying mutant human NADH dehydrogenase 4 gene (hND4/m.11778G>A) to induce retinal ganglion cell (RGC) degeneration and axon loss, the hallmark of the human disease. We then attempted to rescue those mice using a second intravitreal injection of either mitochondrial-targeted or allotopic expressed wildtype human ND4. The rescue of RGCs and their axons were assessed using serial pattern electroretinogram (PERG) and transmission electron microscopy.
Results: Compared to non-rescued LHON controls where PERG amplitude was much reduced, both strategies significantly preserved PERG amplitude over 15 months. However, the rescue effect was more marked with mitochondrial-targeted therapy than with allotopic therapy (p = 0.0128). Post-mortem analysis showed that mitochondrial-targeted human ND4 better preserved small axons that are preferentially lost in human LHON.
Conclusions: These results in a pre-clinical mouse model of LHON suggest that mitochondrially-targeted AAV gene therapy, compared to allotopic AAV gene therapy, is more efficient in rescuing the LHON phenotype.

Keywords:  Leber hereditary optic neuropathy (LHON); allotopic expression; gene therapy; mitochondrial-targeted; mitochondrial-targeted therapy

DOI:  https://doi.org/10.3389/fnins.2023.1119724
Sci Rep. 2023 Apr 08. 13(1): 5788

Possible frequent multiple mitochondrial DNA copies in a single nucleoid in HeLa cells.

Vojtěch Pavluch, Tomáš Špaček, Hana Engstová, Andrea Dlasková, Petr Ježek.

Previously, a number of ~ 1.4 of mitochondrial DNA (mtDNA) molecules in a single nucleoid was reported, which would reflect a minimum nucleoid division. We applied 3D-double-color direct stochastic optical reconstruction microscopy (dSTORM), i.e. nanoscopy with ~ 25-40 nm x,y-resolution, together with our novel method of Delaunay segmentation of 3D data to identify unbiased 3D-overlaps. Noncoding D-loops were recognized in HeLa cells by mtDNA fluorescence in situ hybridization (mtFISH) 7S-DNA 250-bp probe, containing biotin, visualized by anti-biotin/Cy3B-conjugated antibodies. Other mtFISH probes with biotin or Alexa Fluor 647 (A647) against ATP6-COX3 gene overlaps (1,100 bp) were also used. Nucleoids were imaged by anti-DNA/(A647-)-Cy3B-conjugated antibodies. Resulting histograms counting mtFISH-loci/nucleoid overlaps demonstrated that 45% to 70% of visualized nucleoids contained two or more D-loops or ATP6-COX3-loci, indicating two or more mtDNA molecules per nucleoid. With increasing number of mtDNA per nucleoid, diameters were larger and their distribution histograms peaked at ~ 300 nm. A wide nucleoid diameter distribution was obtained also using 2D-STED for their imaging by anti-DNA/A647. At unchanged mtDNA copy number in osteosarcoma 143B cells, TFAM expression increased nucleoid spatial density 1.67-fold, indicating expansion of existing mtDNA and its redistribution into more nucleoids upon the higher TFAM/mtDNA stoichiometry. Validation of nucleoid imaging was also done with two TFAM mutants unable to bend or dimerize, respectively, which reduced both copy number and nucleoid spatial density by 80%. We conclude that frequently more than one mtDNA molecule exists within a single nucleoid in HeLa cells and that mitochondrial nucleoids do exist in a non-uniform size range.

DOI: https://doi.org/10.1038/s41598-023-33012-6