Recurrent De Novo Mutations Disturbing the GTP/GDP Binding Pocket of RAB11B Cause Intellectual Disability and a Distinctive Brain Phenotype

Ideke J. C. Lamers, Margot R. F. Reijnders*, Hanka Venselaar, Alison Kraus, Sandra Jansen, Bert B. A. de Vries, Gunnar Houge, Gyri Aasland Gradek, Jieun Seo, Murim Choi, Jong-Hee Chae, Ineke van der Burgt, Rolph Pfundt, Stef J. F. Letteboer, Sylvia E. C. van Beersum, Simone Dusseljee, Han G. Brunner, Dan Doherty, Tjitske Kleefstra, Ronald Roepman*DDD Study

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

23 Citations (Web of Science)

Abstract

The Rab GTPase family comprises similar to 70 GTP-binding proteins, functioning in vesicle formation, transport and fusion. They are activated by a conformational change induced by GTP-binding, allowing interactions with downstream effectors. Here, we report five individuals with two recurrent de novo missense mutations in RAB11B; c. 64G>A; p.Val22Met in three individuals and c. 202G>A; p.Ala68Thr in two individuals. An overlapping neurodevelopmental phenotype, including severe intellectual disability with absent speech, epilepsy, and hypotonia was observed in all affected individuals. Additionally, visual problems, musculoskeletal abnormalities, and microcephaly were present in the majority of cases. Re-evaluation of brain MRI images of four individuals showed a shared distinct brain phenotype, consisting of abnormal white matter (severely decreased volume and abnormal signal), thin corpus callosum, cerebellar vermis hypoplasia, optic nerve hypoplasia and mild ventriculomegaly. To compare the effects of both variants with known inactive GDP- and active GTP-bound RAB11B mutants, we modeled the variants on the three-dimensional protein structure and performed subcellular localization studies. We predicted that both variants alter the GTP/GDP binding pocket and show that they both have localization patterns similar to inactive RAB11B. Evaluation of their influence on the affinity of RAB11B to a series of binary interactors, both effectors and guanine nucleotide exchange factors (GEFs), showed induction of RAB11B binding to the GEF SH3BP5, again similar to inactive RAB11B. In conclusion, we report two recurrent dominant mutations in RAB11B leading to a neurodevelopmental syndrome, likely caused by altered GDP/GTP binding that inactivate the protein and induce GEF binding and protein mislocalization.

Original languageEnglish
Pages (from-to)824-832
Number of pages9
JournalAmerican Journal of Human Genetics
Volume101
Issue number5
DOIs
Publication statusPublished - 2 Nov 2017

Keywords

  • T-CELL LYMPHOMA
  • RECYCLING ENDOSOME
  • STRUCTURAL BASIS
  • IMAGE-ANALYSIS
  • PROTEIN
  • GTPASES
  • MEMBRANE
  • RHOA
  • CILIOGENESIS
  • SPECIFICITY

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