Mice with a conditional deletion of Talpid3 (KIAA0586) - a model for Joubert Syndrome

Andrew L. Bashford, Vasanta Subramanian

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

Joubert syndrome (JS) is a ciliopathy associated with mutations in numerous genes encoding cilia components. TALPID3 encoded by KIAA0856 in man (2700049A03Rik in mouse) is a centrosomal protein essential for the assembly of primary cilia. Mutations in KIAA0856 have been recently identified in JS patients. Herein, we describe a novel mouse JS model with a conditional deletion of the conserved exons 11–12 of Talpid3 in the central nervous system which recapitulates the complete cerebellar phenotype seen in JS. Talpid3 mutant mice exhibit key hallmarks of JS including progressive ataxia, severely hypoplastic cerebellar hemispheres and vermis, together with abnormal decussation of the superior cerebellar peduncles. The Purkinje cell layer is disorganised with abnormal dendritic arborisation. The external granule layer (EGL) is thinner, lacks primary cilia, and has a reduced level of proliferation. Furthermore, we describe novel cellular defects including ectopic clusters of mature granule neurons, and abnormal parallel fibre-derived synapses and disorientation of cells in the EGL. The defective glial scaffold results in abnormal granule cell migration which manifests as ectopic clusters of granule neurons. In addition, we show a reduction in Wnt7a expression suggesting that defects may arise not only from deficiencies in the Hedgehog (Hh) pathway but also due to the additional roles of Talpid3. The Talpid3 conditional knockout mouse is a novel JS model which fully recapitulates the JS cerebellar phenotype. These findings reveal a role for Talpid3 in granule precursor cell migration in the cerebellum (either direct or indirect) which together with defective Hh signalling underlies the JS phenotype. Our findings also illustrate the utility of creating conditional mouse models to assist in unravelling the molecular and cellular mechanisms underlying JS.

Original languageEnglish
Pages (from-to)396-408
Number of pages13
JournalThe Journal of Pathology
Volume248
Issue number4
Early online date28 Mar 2019
DOIs
Publication statusE-pub ahead of print - 28 Mar 2019

Keywords

  • Joubert syndrome
  • KIAA0586
  • ataxia
  • cerebellum
  • primary cilia
  • sonic hedgehog

ASJC Scopus subject areas

  • Pathology and Forensic Medicine

Cite this

Mice with a conditional deletion of Talpid3 (KIAA0586) - a model for Joubert Syndrome. / Bashford, Andrew L.; Subramanian, Vasanta.

In: The Journal of Pathology, Vol. 248, No. 4, 28.03.2019, p. 396-408.

Research output: Contribution to journalArticle

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