Dysfunction of the ciliary ARMC9/TOGARAM1 protein module causes Joubert syndrome

  • J Clin Invest. 2020 Aug 3;130(8):4423-4439. doi: 10.1172/JCI131656.
Brooke L Latour  1 ,  Julie C Van De Weghe  2 ,  Tamara Ds Rusterholz  3  4 ,  Stef Jf Letteboer  1 ,  Arianna Gomez  2 ,  Ranad Shaheen  5 ,  Matthias Gesemann  4 ,  Arezou Karamzade  6 ,  Mostafa Asadollahi  6 ,  Miguel Barroso-Gil  7 ,  Manali Chitre  8 ,  Megan E Grout  2 ,  Jeroen van Reeuwijk  1 ,  Sylvia Ec van Beersum  1 ,  Caitlin V Miller  2 ,  Jennifer C Dempsey  2 ,  Heba Morsy  9 ,  University of Washington Center for Mendelian Genomics ,  Michael J Bamshad  2  10  11  12 ,  Genomics England Research Consortium ,  Deborah A Nickerson  10  11 ,  Stephan Cf Neuhauss  4 ,  Karsten Boldt  13 ,  Marius Ueffing  13 ,  Mohammad Keramatipour  6 ,  John A Sayer  7 ,  Fowzan S Alkuraya  5  14 ,  Ruxandra Bachmann-Gagescu  3  4 ,  Ronald Roepman  1 ,  Dan Doherty  2  15
Affiliations
  • 1. Department of Human Genetics and Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, Netherlands.
  • 2. Department of Pediatrics, University of Washington, Seattle, Washington, USA.
  • 3. Institute of Medical Genetics, and.
  • 4. Department of Molecular Life Sciences, University of Zurich, Zürich, Switzerland.
  • 5. Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia.
  • 6. Department of Medical Genetics, Faculty of Medicine, Tehran University of Medical Sciences, Tehran, Iran.
  • 7. Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle Upon Tyne, United Kingdom.
  • 8. Department of Paediatric Neurology, Cambridge University Hospitals NHS Foundation Trust, Cambridge, United Kingdom.
  • 9. Department of Human Genetics, Medical Research Institute, Alexandria University, Alexandria, Egypt.
  • 10. The University of Washington Center for Mendelian Genomics is detailed in Supplemental Acknowledgments.
  • 11. University of Washington Center for Mendelian Genomics, Seattle, Washington, USA.
  • 12. Department of Genome Sciences, University of Washington, Seattle, Washington, USA.
  • 13. Medical Proteome Center, Institute for Ophthalmic Research, University of Tuebingen, Tuebingen, Germany.
  • 14. Department of Anatomy and Cell Biology, College of Medicine, Alfaisal University, Riyadh, Saudi Arabia.
  • 15. Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington, USA.
PMID: 32453716 DOI: 10.1172/JCI131656
Abstract

Joubert syndrome (JBTS) is a recessive neurodevelopmental ciliopathy characterized by a pathognomonic hindbrain malformation. All known JBTS genes encode proteins involved in the structure or function of primary cilia, ubiquitous antenna-like organelles essential for cellular signal transduction. Here, we used the recently identified JBTS-associated protein armadillo repeat motif-containing 9 (ARMC9) in tandem-affinity purification and yeast 2-hybrid screens to identify a ciliary module whose dysfunction underlies JBTS. In addition to the known JBTS-associated proteins CEP104 and CSPP1, we identified coiled-coil domain containing 66 (CCDC66) and TOG array regulator of axonemal microtubules 1 (TOGARAM1) as ARMC9 interaction partners. We found that TOGARAM1 variants cause JBTS and disrupt TOGARAM1 interaction with ARMC9. Using a combination of protein interaction analyses, characterization of patient-derived fibroblasts, and analysis of CRISPR/Cas9-engineered zebrafish and hTERT-RPE1 cells, we demonstrated that dysfunction of ARMC9 or TOGARAM1 resulted in short cilia with decreased axonemal acetylation and polyglutamylation, but relatively intact transition zone function. Aberrant serum-induced ciliary resorption and cold-induced depolymerization in ARMC9 and TOGARAM1 patient cell lines suggest a role for this new JBTS-associated protein module in ciliary stability.

Keywords
Genetic diseases; Genetics; Proteomics.