Beta tubulin isoforms are not interchangeable for rescuing impaired radial migration due to Tubb3 knockdown.

Abstract

Over the last years, the critical role of cytoskeletal proteins in cortical development including neuronal migration as well as in neuronal morphology has been well established. Inputs from genetic studies were provided through the identification of several mutated genes encoding either proteins associated with microtubules (DCX, LIS1, KIF2A, KIF5C, DYNC1H1) or tubulin subunits (TUBA1A, TUBB2B, TUBB5 and TUBG1), in malformations of cortical development (MCD). We also reported the identification of missense mutations in TUBB3, the postmitotic neuronal specific tubulin, in six different families presenting either polymicrogyria or gyral disorganization in combination with cerebellar and basal ganglial abnormalities. Here, we investigate further the association between TUBB3 mutations and MCDs by analyzing the consequences of Tubb3 knockdown on cortical development in mice. Using the in utero-electroporation approach, we demonstrate that Tubb3 knockdown leads to delayed bipolar morphology and radial migration with evidence, suggesting that the neuronal arrest is a transient phenomenon overcome after birth. Silenced blocked cells display a round-shape and decreased number of processes and a delay in the acquisition of the bipolar morphology. Also, more Tbr2 positive cells are observed, although less cells express the proliferation marker Ki67, suggesting that Tubb3 inactivation might have an indirect effect on intermediate progenitor proliferation. Furthermore, we show by rescue experiments the non-interchangeability of other beta-tubulins which are unable to rescue the phenotype. Our study highlights the critical and specific role of Tubb3 on the stereotyped morphological changes and polarization processes that are required for initiating radial migration to the cortical plate.

• Authors: Yoann Saillour, Loïc Broix, Elodie Bruel-Jungerman, Nicolas Lebrun, Giuseppe Muraca, Julien Rucci, Karine Poirier, Richard Belvindrah, Fiona Francis, Jamel Chelly
• Journal: Human molecular genetics (Hum Mol Genet) Vol. 23 Issue 6 Pg. 1516-26 (Mar 15 2014) ISSN: 1460-2083 [Electronic] England
• PMID: 24179174 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Dcx protein, mouse
• Doublecortin Protein
• Protein Isoforms
• Tubb3 protein, mouse
• Tubulin

Topics

• Animals
• Cell Movement
• Cerebral Cortex (metabolism)
• Doublecortin Protein
• Electroporation
• Female
• Gene Knockdown Techniques
• Humans
• Malformations of Cortical Development (genetics, pathology)
• Mice
• Mutation, Missense
• Pregnancy
• Protein Isoforms
• Tubulin (genetics, metabolism)