Mutations in TRAF3IP1/IFT54 reveal a new role for IFT proteins in microtubule stabilization

Nat Commun. 2015 Oct 21;6:8666. doi: 10.1038/ncomms9666.

Abstract

Ciliopathies are a large group of clinically and genetically heterogeneous disorders caused by defects in primary cilia. Here we identified mutations in TRAF3IP1 (TNF Receptor-Associated Factor Interacting Protein 1) in eight patients from five families with nephronophthisis (NPH) and retinal degeneration, two of the most common manifestations of ciliopathies. TRAF3IP1 encodes IFT54, a subunit of the IFT-B complex required for ciliogenesis. The identified mutations result in mild ciliary defects in patients but also reveal an unexpected role of IFT54 as a negative regulator of microtubule stability via MAP4 (microtubule-associated protein 4). Microtubule defects are associated with altered epithelialization/polarity in renal cells and with pronephric cysts and microphthalmia in zebrafish embryos. Our findings highlight the regulation of cytoplasmic microtubule dynamics as a role of the IFT54 protein beyond the cilium, contributing to the development of NPH-related ciliopathies.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Blotting, Western
  • Carrier Proteins / genetics*
  • Carrier Proteins / metabolism
  • Cell Polarity / genetics
  • Circular Dichroism
  • Embryo, Nonmammalian
  • Female
  • Fluorescent Antibody Technique
  • Gene Knockout Techniques
  • HEK293 Cells
  • High-Throughput Nucleotide Sequencing
  • Humans
  • Immunoprecipitation
  • Kidney Diseases, Cystic / genetics*
  • Kidney Diseases, Cystic / metabolism
  • Male
  • Microphthalmos / genetics
  • Microtubule-Associated Proteins / genetics*
  • Microtubule-Associated Proteins / metabolism*
  • Microtubules / metabolism*
  • Mutation*
  • Pedigree
  • Retinal Degeneration / genetics*
  • Retinal Degeneration / metabolism
  • Reverse Transcriptase Polymerase Chain Reaction
  • Zebrafish
  • Zebrafish Proteins / genetics*
  • Zebrafish Proteins / metabolism

Substances

  • Carrier Proteins
  • MAP4 protein, human
  • Microtubule-Associated Proteins
  • TRAF3IP1 protein, human
  • Zebrafish Proteins
  • traf3ip1 protein, zebrafish