The Roles of Tubulins in the Developing Mouse Brain

The Roles of Tubulins in the Developing Mouse Brain

Bibliographic Details
Main Author: Bittermann, Elizabeth A.
Language:English
Published: University of Cincinnati / OhioLINK 2018
Subjects:
Genetics
Tubulin
Tuba1a
Tubb2a
Tubb2b
Developing brain
Cortical Malformation
Online Access:http://rave.ohiolink.edu/etdc/view?acc_num=ucin1523630790076922
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spelling ndltd-OhioLink-oai-etd.ohiolink.edu-ucin15236307900769222021-08-03T07:06:04Z The Roles of Tubulins in the Developing Mouse Brain Bittermann, Elizabeth A. Genetics Tubulin Tuba1a Tubb2a Tubb2b Developing brain Cortical Malformation The tubulin genes form a superfamily composed of eight alpha-tubulins, nine beta-tubulins, and two gamma-tubulins. Together these form microtubules which are important for cell motility, membrane structure, cilia structure, and neuron extension support. The alpha- and beta-tubulins alternate to form cylindrical structures, which are nucleated by gamma-tubulins, to bind laterally and form the tube structure of the microtubule. Elongation of the microtubule is critical for neurite extension during neuronal migration. Neuronal migration is, in turn critical for proper brain development. Neurons have both radial and tangential migration routes which are crucial for proper brain architecture. To date, mutations have been found in ten of the human tubulin genes. Eight have been linked to brain phenotypes including polymicrogyria, lissencephaly, enlarged ventricles, and microcephaly. <i>TUBA1A</i> is one of these, with two homologs which have almost identical amino acid sequences. <i>TUBB2A</i> and <i>TUBB2B</i> are two of the eight genes with brain phenotypes, which have almost identical amino acid sequences. There have only been four mouse models of tubulin mutations to model the different brain phenotypes, but none were designed to precisely recapitulate variants found in humans. All four mice were made through ENU screens. The severity of these phenotypes is surprising as the high homology between genes suggests they may be able to compensate for each other. Here we used CRISPR-CAS9 genome editing and created five novel alleles with the deletion of <i>Tubb2a</i>, <i>Tubb2b</i>, and <i>Tuba1a</i>. We also acquired a null allele of <i>Tuba8</i>. <i>Tubb2a<sup>d3964</sup></i>, <i>Tubb2a<sup>d4223</sup></i>, <i>Tubb2b<sup>d4183</sup></i>, and <i>Tuba8<sup>em1J</sup></i> mice were all viable and fertile in the homozygous state, with no difference in size. <i>Tuba1a</i> homozygous loss led to embryonic lethality. Deletion of <i>Tuba1a</i> produced mice that had enlarged ventricles with loss of the intermediate zone of the cortex, and about a 25% incidence of cleft palate. The <i>Tuba1a<sup>quas</sup></i> was previously identified through an ENU screen with an R215* nonsense mutation. <i>Tuba1a<sup>quas</sup></i> mutants have a phenotype similar to the <i>Tuba1a</i> null, with enlarged ventricles and a loss of intermediate zone. A complementation test between <i>Tuba1a<sup>d4353/wt</sup></i> and <i>Tuba1a<sup>quas/wt</sup></i> produced no live animals with both mutations, confirming the <i>Tuba1a</i> R215* mutation to be an allele of <i>Tuba1a</i>. Preliminary molecular characterization of these <i>Tuba1a</i> phenotypes indicated an increase in proliferation and differentiation of neurons in <i>Tuba1a<sup>quas</sup></i> mutants. Similar analysis of the <i>Tuba1a<sup>d4353</sup></i> mutants also suggested a possible decrease in proliferation and an increase in differentiation of neurons. Overall, <i>Tuba1a</i> is critical for brain development, but <i>Tubb2a</i> and <i>Tubb2b</i> have the ability to compensate for each other. 2018-09-04 English text University of Cincinnati / OhioLINK http://rave.ohiolink.edu/etdc/view?acc_num=ucin1523630790076922 http://rave.ohiolink.edu/etdc/view?acc_num=ucin1523630790076922 unrestricted This thesis or dissertation is protected by copyright: all rights reserved. It may not be copied or redistributed beyond the terms of applicable copyright laws.
collection NDLTD
language English
sources NDLTD
topic Genetics
Tubulin
Tuba1a
Tubb2a
Tubb2b
Developing brain
Cortical Malformation
spellingShingle Genetics
Tubulin
Tuba1a
Tubb2a
Tubb2b
Developing brain
Cortical Malformation
Bittermann, Elizabeth A.
The Roles of Tubulins in the Developing Mouse Brain
author Bittermann, Elizabeth A.
author_facet Bittermann, Elizabeth A.
author_sort Bittermann, Elizabeth A.
title The Roles of Tubulins in the Developing Mouse Brain
title_short The Roles of Tubulins in the Developing Mouse Brain
title_full The Roles of Tubulins in the Developing Mouse Brain
title_fullStr The Roles of Tubulins in the Developing Mouse Brain
title_full_unstemmed The Roles of Tubulins in the Developing Mouse Brain
title_sort roles of tubulins in the developing mouse brain
publisher University of Cincinnati / OhioLINK
publishDate 2018
url http://rave.ohiolink.edu/etdc/view?acc_num=ucin1523630790076922
work_keys_str_mv AT bittermannelizabetha therolesoftubulinsinthedevelopingmousebrain
AT bittermannelizabetha rolesoftubulinsinthedevelopingmousebrain
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