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- Brunetti, Dario, et al.
(författare)
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Defective PITRM1 mitochondrial peptidase is associated with A amyloidotic neurodegeneration
- 2016
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Ingår i: EMBO Molecular Medicine. - : EMBO. - 1757-4676 .- 1757-4684. ; 8:3, s. 176-190
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Tidskriftsartikel (refereegranskat)abstract
- Mitochondrial dysfunction and altered proteostasis are central features of neurodegenerative diseases. The pitrilysin metallopeptidase 1 (PITRM1) is a mitochondrial matrix enzyme, which digests oligopeptides, including the mitochondrial targeting sequences that are cleaved from proteins imported across the inner mitochondrial membrane and the mitochondrial fraction of amyloid beta (A). We identified two siblings carrying a homozygous PITRM1 missense mutation (c.548G>A, p.Arg183Gln) associated with an autosomal recessive, slowly progressive syndrome characterised by mental retardation, spinocerebellar ataxia, cognitive decline and psychosis. The pathogenicity of the mutation was tested invitro, in mutant fibroblasts and skeletal muscle, and in a yeast model. A Pitrm1(+/-) heterozygous mouse showed progressive ataxia associated with brain degenerative lesions, including accumulation of A-positive amyloid deposits. Our results show that PITRM1 is responsible for significant A degradation and that impairment of its activity results in A accumulation, thus providing a mechanistic demonstration of the mitochondrial involvement in amyloidotic neurodegeneration.
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- Langer, Yeshaya, et al.
(författare)
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Mitochondrial PITRM1 peptidase loss-of-function in childhood cerebellar atrophy
- 2018
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Ingår i: Journal of Medical Genetics. - : BMJ. - 0022-2593 .- 1468-6244. ; 55:9, s. 599-606
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Tidskriftsartikel (refereegranskat)abstract
- Objective To identify the genetic basis of a childhood-onset syndrome of variable severity characterised by progressive spinocerebellar ataxia, mental retardation, psychotic episodes and cerebellar atrophy. Methods Identification of the underlying mutations by whole exome and whole genome sequencing. Consequences were examined in patients' cells and in yeast. Results Two brothers from a consanguineous Palestinian family presented with progressive spinocerebellar ataxia, mental retardation and psychotic episodes. Serial brain imaging showed severe progressive cerebellar atrophy. Whole exome sequencing revealed a novel mutation: pitrilysin metallopeptidase 1 (PITRM1) c.2795C>T, p.T931M, homozygous in the affected children and resulting in 95% reduction in PITRM1 protein. Whole genome sequencing revealed a chromosome X structural rearrangement that also segregated with the disease. Independently, two siblings from a second Palestinian family presented with similar, somewhat milder symptoms and the same PITRM1 mutation on a shared haplotype. PITRM1T931M carrier frequency was 0.027 (3/110) in the village of the first family evaluated, and 0/300 among Palestinians from other locales. PITRM1 is a mitochondrial matrix enzyme that degrades 10-65 amino acid oligopeptides, including the mitochondrial fraction of amyloid-beta peptide. Analysis of peptide cleavage activity by the PITRM1T931M protein revealed a significant decrease in the degradation capacity specifically of peptides >= 40 amino acids. Conclusion PITRM1T931M results in childhood-onset recessive cerebellar pathology. Severity of PITRM1-related disease may be affected by the degree of impairment in cleavage of mitochondrial long peptides. Disruption and deletion of X linked regulatory segments may also contribute to severity.
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