Affiliation:
1. Newlife Birth Defects Research Centre, UCL GOS Institute of Child Health, University College London, 30 Guilford Street, London WC1N 1EH, UK
Abstract
Encephalocele is a clinically important birth defect that can lead to severe disability in childhood and beyond. The embryonic and early fetal pathogenesis of encephalocele is poorly understood and, while usually classified as a ‘neural tube defect’, there is conflicting evidence on whether encephalocele results from defective neural tube closure, or is a post-neurulation defect. It is also unclear whether encephalocele can result from the same causative factors as anencephaly and open spina bifida, or whether it is aetiologically distinct. This lack of information results largely from the scarce availability of animal models of encephalocele, particularly ones that resemble the commonest, non-syndromic human defects. Here, we report a novel mouse model of occipito-parietal encephalocele, in which the small GTPase Rac1 is conditionally ablated in the (non-neural) surface ectoderm. Most mutant fetuses have open spina bifida, and some also exhibit exencephaly/anencephaly. However, a proportion of mutant fetuses exhibit brain herniation, affecting the occipito-parietal region and closely resembling encephalocele. The encephalocele phenotype does not result from defective neural tube closure, but rather from a later disruption of the surface ectoderm covering the already closed neural tube, allowing the brain to herniate. The neuroepithelium itself shows no down-regulation of Rac1 and appears morphologically normal until late gestation. A large skull defect overlies the region of brain herniation. Our work provides a new genetic model of occipito-parietal encephalocele, particularly resembling non-syndromic human cases. While encephalocele has a different, later-arising pathogenesis than open neural tube defects, both can share the same genetic causation.
Funder
Wellcome Trust
National Institute for Health Research Biomedical Research Centre at Great Ormond Street Hospital for Children NHS Foundation Trust and UCL GOS Institute of Child Health
Great Ormond Street Hospital Charity
Publisher
The Company of Biologists
Subject
General Biochemistry, Genetics and Molecular Biology,Immunology and Microbiology (miscellaneous),Medicine (miscellaneous),Neuroscience (miscellaneous)
Cited by
23 articles.
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