title: Gastrointestinal dysmotility in mitochondrial neurogastrointestinal encephalomyopathy is caused by mitochondrial DNA depletion.
abstract: Chronic intestinal pseudo-obstruction is a life-threatening condition of unknown pathogenic mechanisms. Chronic intestinal pseudo-obstruction can be a feature of mitochondrial disorders, such as mitochondrial neurogastrointestinal encephalomyopathy (MNGIE), a rare autosomal-recessive syndrome, resulting from mutations in the thymidine phosphorylase gene. MNGIE patients show elevated circulating levels of thymidine and deoxyuridine, and accumulate somatic mitochondrial DNA (mtDNA) defects. The present study aimed to clarify the molecular basis of chronic intestinal pseudo-obstruction in MNGIE. Using laser capture microdissection, we correlated the histopathological features with mtDNA defects in different tissues from the gastrointestinal wall of five MNGIE and ten control patients. We found mtDNA depletion, mitochondrial proliferation, and smooth cell atrophy in the external layer of the muscularis propria, in the stomach and in the small intestine of MNGIE patients. In controls, the lowest amounts of mtDNA were present at the same sites, as compared with other layers of the gastrointestinal wall. We also observed mitochondrial proliferation and mtDNA depletion in small vessel endothelial and smooth muscle cells. Thus, visceral mitochondrial myopathy likely causes gastrointestinal dysmotility in MNGIE patients. The low baseline abundance of mtDNA molecules may predispose smooth muscle cells of the muscularis propria external layer to the toxic effects of thymidine and deoxyuridine, and exposure to high circulating levels of nucleosides may account for the mtDNA depletion observed in the small vessel wall.
authors.affiliation: Dipartimento di Medicina Sperimentale, Sapienza, Università di Roma, Roma, Italy.
authors.forename: Carla
authors.initials: C
authors.lastname: Giordano
authors.forename: Mariangela
authors.initials: M
authors.lastname: Sebastiani
authors.forename: Roberto
authors.initials: R
authors.lastname: De Giorgio
authors.forename: Claudia
authors.initials: C
authors.lastname: Travaglini
authors.forename: Andrea
authors.initials: A
authors.lastname: Tancredi
authors.forename: Maria Lucia
authors.initials: ML
authors.lastname: Valentino
authors.forename: Marzio
authors.initials: M
authors.lastname: Bellan
authors.forename: Andrea
authors.initials: A
authors.lastname: Cossarizza
authors.forename: Michio
authors.initials: M
authors.lastname: Hirano
authors.forename: Giulia
authors.initials: G
authors.lastname: d'Amati
authors.forename: Valerio
authors.initials: V
authors.lastname: Carelli
mesh_terms: D000328:Adult; D004272:DNA, Mitochondrial / Q000235:genetics*; D042783:Endothelial Cells / Q000473:pathology; D004947:Esophagus / Q000473:pathology; D005260:Female; D005767:Gastrointestinal Diseases / Q000473:pathology / Q000503:physiopathology*; D005769:Gastrointestinal Motility / Q000502:physiology*; D041981:Gastrointestinal Tract / Q000378:metabolism / Q000473:pathology; D006801:Humans; D008297:Male; D042282:Microdissection; D017237:Mitochondrial Encephalomyopathies / Q000473:pathology / Q000503:physiopathology*; D032389:Myocytes, Smooth Muscle / Q000473:pathology; D017354:Point Mutation / Q000235:genetics; D017384:Sequence Deletion
chemical_list: D004272:DNA, Mitochondrial
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