A conditional mutant allele for analysis of Mixl1 function in the mouse. Issue 5 (13th March 2014)

• Record Type: Journal Article
• Authors: Pulina, Maria V.; Sahr, Kenneth E.; Nowotschin, Sonja; Baron, Margaret H.; Hadjantonakis, Anna‐Katerina
• Is Part Of: Genesis. Volume 52:Issue 5(2014:May)
• Page Start: 417
• Page End: 423
• Publication Date: 2014-03-13
• Subjects: Developmental genetics -- Periodicals; Genetics -- Periodicals; Developmental biology -- Periodicals; Embryology -- Periodicals; Genetic regulation -- Periodicals; 576.5
• DOI: 10.1002/dvg.22768
• Languages: English
• ISSNs: 1526-954X

Abstract

<abstract abstract-type="main"> <title>Summary</title> <p> <italic>Mixl1</italic> is the only member of the <italic>Mix/Bix</italic> homeobox gene family identified in mammals. During mouse embryogenesis, <italic>Mixl1</italic> is first expressed at embryonic day (E)5.5 in cells of the visceral endoderm (VE). At the time of gastrulation, <italic>Mixl1</italic> expression is detected in the vicinity of the primitive streak. <italic>Mixl1</italic> is expressed in cells located within the primitive streak, in nascent mesoderm cells exiting the primitive streak, and in posterior VE overlying the primitive streak. Genetic ablation of <italic>Mixl1</italic> in mice has revealed its crucial role in mesoderm and endoderm cell specification and tissue morphogenesis during early embryonic development. However, the early lethality of the constitutive <italic>Mixl1<sup>−</sup></italic><sup>/−</sup> mutant precludes the study of its role at later stages of embryogenesis and in adult mice. To circumvent this limitation, we have generated a conditional <italic>Mixl1</italic> allele (<italic>Mixl1<sup>c</sup><sup>KO</sup></italic>) that permits temporal as well as spatial control of gene ablation. Animals homozygous for the <italic>Mixl1<sup>c</sup><sup>KO</sup></italic> conditional allele were viable and fertile. <italic>Mixl1<sup>KO</sup><sup>/</sup><sup>KO</sup></italic> embryos generated by crossing of <italic>Mixl1<sup>c</sup><sup>KO</sup><sup>/c</sup><sup>KO</sup></italic> mice with <italic>Sox2‐Cre</italic> or <italic>EIIa‐Cre</italic> transgenic mice were embryonic lethal at early somite stages. By contrast to wild‐type embryos, <italic>Mixl1<sup>KO</sup><sup>/</sup><sup>KO</sup></italic> embryos contained no detectable Mixl1, validating the <italic>Mixl1<sup>c</sup><sup>KO</sup></italic> as a protein null after Cre‐mediated excision. <italic>Mixl1<sup>KO</sup><sup>/</sup><sup>KO</sup></italic> embryos resembled the previously reported <italic>Mixl1<sup>−</sup><sup>/</sup><sup>−</sup></italic> mutant phenotype. Therefore, the <italic>Mixl1</italic> cKO allele provides a tool for investigating the temporal and tissue‐specific requirements for <italic>Mixl1</italic> in the mouse. genesis 52:417–423, 2014. © 2014 Wiley Periodicals, Inc.</p> </abstract>