Planar cell polarity signalling and mammalian neurulation

Lead Research Organisation: University College London
Department Name: Institute of Child Health

Abstract

During early pregnancy, a crucial event in the developing embryo is the formation of the neural tube , which will later develop into the brain and spinal cord. Failure of the neural tube to form correctly leads to a group of birth defects called neural tube defects (NTDs), in which the brain and/or spinal cord of the fetus become irreversibly damaged, resulting in death before or shortly after birth, or handicap in surviving babies. Overall, NTDs occur in around 1 per 1,000 pregnancies although the rate varies and is significantly higher in some regions (e.g. Northern Ireland and Scotland). Worldwide, approximately 130,000 cases occur every year. The risk of NTDs depends on both inherited genetic factors and non-genetic factors such as diet, but the exact causes are not well understood. However, the risk of an affected pregnancy can be substantially reduced if the mother takes folic acid supplements before and during early pregnancy. Unfortunately, not all cases of NTDs are preventable by folic acid and it seems that to make further progress in prevention of NTDs will require a deeper understanding of the underlying causes of the defects (both genetic and environmental). Recent studies have revealed several genes, which when mutated in mice, prevent the initial step of neural tube closure, resulting in severe spina bifida. Significantly, these genes all seem to be involved in the same biochemical pathway, called the planar cell polarity pathway, which appears to be needed for co-ordinated movement of cells in the early embryo. In this project we will focus on these genes, to determine their specific function in the developing mouse embryo, and to understand how this is essential for the neural tube to form. Although these developmental studies will be carried out in mouse models, we have recently found that some humans with severe spina bifida also carry alterations in planar cell polarity genes. We plan to test whether these alterations (or mutations) are responsible for spina bifida in patients with NTDs, by testing the effect of the same mutation in mice. Identification of ?risk? genes will provide an opportunity to offer genetic counselling to couples who have affected pregnancies, and will be a key step towards developing new personalised therapies for prevention of NTDs.

Technical Summary

Neurulation - formation of the neural tube - is a critical event in development of the central nervous system. Neural tube closure is initiated at the hindbrain/cervical boundary (Closure 1), after which closure occurs progressively and independently in brain and spine. Failure of any aspect of neurulation leads to neural tube defects (NTDs), a group of severe congenital malformations that are lethal at birth (e.g. anencephaly) or cause severe handicap in survivors (e.g. open spina bifida). The causes of human NTDs appear complex and multifactorial, involving both genetic and environmental factors, although major causative genes have yet to be identified. Determination of the underlying developmental mechanisms and identification of genetic risk factors would be an important step towards development of improved genetic counseling for NTDs and new preventive strategies.

Many mouse mutants develop NTDs, providing model systems for experimental analysis. A recent advance was the finding that mutations in genes of the planar cell polarity (PCP) signalling pathway cause the most severe NTD, craniorachischisis. In this condition, the hindbrain and entire spinal cord remain open as a result of failure of Closure 1. Mechanistically, PCP signalling seems to be required for correct regulation of cell movements that both narrow and lengthen the embryo during gastrulation, a process called convergent extension. The purpose of the present proposal is to build upon recent studies, by ourselves and others, that link PCP signalling with mouse NTDs. We will analyse in detail the role of PCP signalling in neurulation mechanisms, and investigate the possible role of PCP genes in causation of human NTDs. Specifically, we aim to:

1. Investigate the developmental link(s) between PCP signalling, convergent extension and initiation of neural tube closure. We will determine in which tissue PCP signalling is required, whether the function of PCP genes is cell autonomous or non-autonomous, and whether convergent extension also requires PCP independent cell-matrix interactions.

2. Determine the mechanisms by which PCP gene mutations predispose to defects of later spinal neurulation, that result in open spina bifida. These studies will address the possible role of convergent extension after initiation of neurulation.

3. Test putative mutations in PCP genes, that we have identified in human NTD cases, for functional effects on neural tube closure. This will be achieved by generation of equivalent mutations in knockin mice, and examination of knockin embryos for disturbance of convergent extension and neurulation.

Publications

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Abdul-Aziz NM (2009) EphrinA-EphA receptor interactions in mouse spinal neurulation: implications for neural fold fusion. in The International journal of developmental biology

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Copp AJ (2013) Neural tube defects--disorders of neurulation and related embryonic processes. in Wiley interdisciplinary reviews. Developmental biology

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Copp AJ (2010) Defining a PARticular pathway of neural tube closure. in Developmental cell

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Copp AJ (2011) Regional differences in the expression of laminin isoforms during mouse neural tube development. in Matrix biology : journal of the International Society for Matrix Biology

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Copp AJ (2010) Genetics and development of neural tube defects. in The Journal of pathology

 
Description Anatomical Society PhD studentship
Amount £78,198 (GBP)
Organisation Anatomical Society 
Sector Learned Society
Country United Kingdom
Start 10/2017 
End 09/2020
 
Description Bo Hjelt PhD Studentship
Amount £94,500 (GBP)
Organisation Hjelt Foundations 
Department Bo Hjelt Foundation for Spina Bifida
Sector Charity/Non Profit
Country Switzerland
Start 11/2012 
End 10/2015
 
Description Bo Hjelt PhD studentship (2017-2021)
Amount € 135,000 (EUR)
Organisation Hjelt Foundations 
Sector Charity/Non Profit
Country Switzerland
Start 10/2017 
End 09/2021
 
Description Cellular mechanisms underlying the morphogenetic biomechanics of mammalian neural tube closure
Amount £1,101,901 (GBP)
Funding ID 211112/Z/18/Z 
Organisation Wellcome Trust 
Sector Charity/Non Profit
Country United Kingdom
Start 10/2018 
End 09/2023
 
Description GOSHCC PhD Studentship
Amount £35,572 (GBP)
Funding ID V1295 
Organisation Great Ormond Street Hospital Children's Charity (GOSHCC) 
Sector Charity/Non Profit
Country United Kingdom
Start 10/2013 
End 09/2016
 
Description PhD Studentship
Amount £90,000 (GBP)
Funding ID NC/M001555/1 
Organisation National Centre for the Replacement, Refinement and Reduction of Animals in Research (NC3Rs) 
Sector Private
Country United Kingdom
Start 10/2015 
End 09/2018
 
Description Postdoctoral Clinical Research Training Fellowship
Amount £323,348 (GBP)
Funding ID 107474/Z/2015/Z 
Organisation Wellcome Trust 
Sector Charity/Non Profit
Country United Kingdom
Start 10/2015 
End 09/2018
 
Title Biomechanical methods in neurulation research 
Description Application of confocal-based imaging and laser ablation to determine biomechanical events during neural tube closure 
Type Of Material Technology assay or reagent 
Year Produced 2017 
Provided To Others? Yes  
Impact Has enabled a new line of research in to biomechanics in our lab, plus considerable interest from groups outside our department. 
 
Title Planar polarity assessment in mouse embryos 
Description Assessment of features of the planar cell polarity phenotype in mouse embryos using: e.g. electroporation of lineage marker into the embryonic node followed by embryo culture 
Type Of Material Technology assay or reagent 
Year Produced 2012 
Provided To Others? Yes  
Impact Widespread uptake of planar cell polarity analysis in mouse embryos 
URL https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3616368/
 
Description MRC Mouse Network 
Organisation MRC Harwell
Country United Kingdom 
Sector Academic/University 
PI Contribution Formed the Developmental Anomalies Consortium, as part of the MRC Mouse Network
Collaborator Contribution Providing new knockout mice in areas of interest to our consortium
Impact Publications on establishment of the Network, 2013. Provision of new Chrdl1 mouse mutant, 2016.
Start Year 2011
 
Description PCP bone collaboration 
Organisation University of Bristol
Country United Kingdom 
Sector Academic/University 
PI Contribution Provision of mutant Vangl2 mice for bone PCP analysis
Collaborator Contribution Provision of expertise in bone PCP analysis
Impact Joint publication in J Bone Miner Res, 2014
Start Year 2012
 
Description PKN collaboration 
Organisation Queen Mary University of London
Department Barts Cancer Institute
Country United Kingdom 
Sector Academic/University 
PI Contribution Analysis of PKN2 knockout mouse embryos using our expertise in developmental biology, especially neural crest cell migration
Collaborator Contribution Provided PKN2 knockout mice, and led the collaboration
Impact Publication of the following paper has resulted from the collaboration: Quetier I., Marshall J.J., Spencer-Dene B., Lachmann S., Casamassima A., Franco C., Escuin S., Worrall J.T., Baskaran P., Rajeeve V., Howell M., Copp A.J., Stamp G., Rosewell I., Cutillas P., Gerhardt H., Parker P.J., and Cameron A.J. (2016). Knockout of the PKN Family of Rho Effector Kinases Reveals a Non-redundant Role for PKN2 in Developmental Mesoderm Expansion. Cell Rep. 14: 440-448.
Start Year 2013
 
Description Syndecan 4 collaboration 
Organisation Pontifical Catholic University of Chile
Country Chile 
Sector Academic/University 
PI Contribution Training of PhD student from Chile. Performance of lab research in my department. Led to joint publication in 2013
Collaborator Contribution Scientific collaboration by group in Chile with contribution of novel data
Impact Publication in Development, 2013
Start Year 2010
 
Description BBC Horizon, Spina Bifida & Me 
Form Of Engagement Activity A broadcast e.g. TV/radio/film/podcast (other than news/press)
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Public/other audiences
Results and Impact BBC Horizon programme on Spina Bifida. Prof Copp was featured in the programme.
Year(s) Of Engagement Activity 2018
URL https://www.bbc.co.uk/programmes/b0bcmjht