BROMI/TBC1D32 together with CCRK/CDK20 and FAM149B1/JBTS36 contributes to intraflagellar transport turnaround involving ICK/CILK1

Mol Biol Cell. 2022 Aug 1;33(9):ar79. doi: 10.1091/mbc.E22-03-0089. Epub 2022 May 24.

Abstract

Primary cilia are antenna-like organelles that contain specific proteins, and are crucial for tissue morphogenesis. Anterograde and retrograde trafficking of ciliary proteins are mediated by the intraflagellar transport (IFT) machinery. BROMI/TBC1D32 interacts with CCRK/CDK20, which phosphorylates and activates the intestinal cell kinase (ICK)/CILK1 kinase, to regulate the change in direction of the IFT machinery at the ciliary tip. Mutations in BROMI, CCRK, and ICK in humans cause ciliopathies, and mice defective in these genes are also known to demonstrate ciliopathy phenotypes. We show here that BROMI interacts not only with CCRK but also with CFAP20, an evolutionarily conserved ciliary protein, and with FAM149B1/ Joubert syndrome (JBTS)36, a protein in which mutations cause JBTS. In addition, we show that FAM149B1 interacts directly with CCRK as well as with BROMI. Ciliary defects observed in CCRK-knockout (KO), BROMI-KO, and FAM149B1-KO cells, including abnormally long cilia and accumulation of the IFT machinery and ICK at the ciliary tip, resembled one another, and BROMI mutants that are defective in binding to CCRK and CFAP20 were unable to rescue the ciliary defects of BROMI-KO cells. These data indicate that CCRK, BROMI, FAM149B1, and probably CFAP20 altogether regulate the IFT turnaround process under the control of ICK.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adaptor Proteins, Signal Transducing / metabolism
  • Animals
  • Biological Transport
  • Cilia / metabolism
  • Ciliopathies* / metabolism
  • Cyclin-Dependent Kinase-Activating Kinase
  • Cyclin-Dependent Kinases
  • Cytoskeletal Proteins
  • Eye Abnormalities* / metabolism
  • Humans
  • Kidney Diseases, Cystic* / metabolism
  • Mice
  • Protein Serine-Threonine Kinases
  • Protein Transport
  • Proteins / metabolism

Substances

  • Adaptor Proteins, Signal Transducing
  • Cytoskeletal Proteins
  • FAM149B1 protein, human
  • Proteins
  • TBC1D32 protein, human
  • CILK1 protein, human
  • Protein Serine-Threonine Kinases
  • Cyclin-Dependent Kinases
  • Cyclin-Dependent Kinase-Activating Kinase