A missense allele of PEX5 is responsible for the defective import of PTS2 cargo proteins into peroxisomes
Male
Mice, Knockout
0303 health sciences
Chromosomes, Human, Pair 12
Peroxisome-Targeting Signal 1 Receptor
Genetic Linkage
Mutation, Missense
Biological Transport, Active
Cataract
Peroxisomal Targeting Signals
Consanguinity
Mice
03 medical and health sciences
Lens, Crystalline
Sequestosome-1 Protein
Exome Sequencing
Peroxisomes
Animals
Humans
ATP-Binding Cassette Transporters
Female
DOI:
10.1007/s00439-020-02238-z
Publication Date:
2021-01-02T21:13:09Z
AUTHORS (25)
ABSTRACT
Peroxisomes, single-membrane intracellular organelles, play an important role in various metabolic pathways. The translocation of proteins from the cytosol to peroxisomes depends on peroxisome import receptor proteins and defects in peroxisome transport result in a wide spectrum of peroxisomal disorders. Here, we report a large consanguineous family with autosomal recessive congenital cataracts and developmental defects. Genome-wide linkage analysis localized the critical interval to chromosome 12p with a maximum two-point LOD score of 4.2 (θ = 0). Next-generation exome sequencing identified a novel homozygous missense variant (c.653 T > C; p.F218S) in peroxisomal biogenesis factor 5 (PEX5), a peroxisome import receptor protein. This missense mutation was confirmed by bidirectional Sanger sequencing. It segregated with the disease phenotype in the family and was absent in ethnically matched control chromosomes. The lens-specific knockout mice of Pex5 recapitulated the cataractous phenotype. In vitro import assays revealed a normal capacity of the mutant PEX5 to enter the peroxisomal Docking/Translocation Module (DTM) in the presence of peroxisome targeting signal 1 (PTS1) cargo protein, be monoubiquitinated and exported back into the cytosol. Importantly, the mutant PEX5 protein was unable to form a stable trimeric complex with peroxisomal biogenesis factor 7 (PEX7) and a peroxisome targeting signal 2 (PTS2) cargo protein and, therefore, failed to promote the import of PTS2 cargo proteins into peroxisomes. In conclusion, we report a novel missense mutation in PEX5 responsible for the defective import of PTS2 cargo proteins into peroxisomes resulting in congenital cataracts and developmental defects.
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