The Leber congenital amaurosis protein AIPL1 modulates the nuclear translocation of NUB1 and suppresses inclusion formation by NUB1 fragments

J Biol Chem. 2004 Nov 12;279(46):48038-47. doi: 10.1074/jbc.M407871200. Epub 2004 Aug 30.

Abstract

Mutations in the aryl hydrocarbon receptor-interacting protein-like 1 (AIPL1) cause the blinding disease Leber congenital amaurosis (LCA). The similarity of AIPL1 to AIP has led to suggestions that AIPL1 could function in a similar manner to AIP in facilitating protein translocation and as a component of chaperone complexes. AIPL1 interacts with the cell cycle regulator NEDD8 ultimate buster protein 1 (NUB1). As AIPL1 is predominantly cytoplasmic and NUB1 is predominantly nuclear, we tested the hypothesis that AIPL1 could modulate the nuclear translocation of NUB1. Co-transfection of AIPL1 with GFP-NUB1 resulted in a shift of GFP-NUB1 subcellular distribution toward the cytoplasm. Interestingly, AIPL1 was able to act in a chaperone-like fashion to efficiently suppress inclusion formation by NUB1 fragments. Co-transfection of AIPL1 with GFP-NUB1-N and GFP-NUB1-C resulted in an AIPL1-dependent suppression of GFP-NUB1-N perinuclear inclusions and GFP-NUB1-C intranuclear inclusions leading to the redistribution of these fragments in the cytoplasm. This chaperone-like function of AIPL1 was specific for NUB1, since AIPL1 was unable to suppress the inclusion formation by unrelated aggregation-prone proteins and AIP had no effect on NUB1 localization or inclusion formation. We examined the effect of a range of pathogenic and engineered mutations on the ability of AIPL1 to modulate NUB1 localization or inclusion formation. With the exception of W278X, which formed non-functional SDS-insoluble inclusions, all of the pathogenic mutations studied were soluble and could modulate NUB1 with varying efficiency compared with the wild-type protein. The effect of AIPL1 on NUB1 required the C-terminal region of AIPL1, as engineered C-terminal truncation mutations had no effect on NUB1. These data show that AIPL1 can modulate protein translocation and act in a chaperone-like manner and suggest that AIPL1 is an important modulator of NUB1 cellular function.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Active Transport, Cell Nucleus / physiology*
  • Adaptor Proteins, Signal Transducing
  • Carrier Proteins / genetics
  • Carrier Proteins / metabolism*
  • Cell Line, Tumor
  • Eye Proteins
  • Humans
  • Inclusion Bodies / metabolism*
  • Mutation
  • Optic Atrophy, Hereditary, Leber / genetics
  • Optic Atrophy, Hereditary, Leber / metabolism
  • Peptide Fragments / metabolism*
  • Protein Structure, Tertiary
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism
  • Transcription Factors / genetics
  • Transcription Factors / metabolism*

Substances

  • AIPL1 protein, human
  • Adaptor Proteins, Signal Transducing
  • Carrier Proteins
  • Eye Proteins
  • NUB1 protein, human
  • Peptide Fragments
  • Recombinant Fusion Proteins
  • Transcription Factors