Award details

Characterising Epithelial Cell Movements during Anterior Patterning

Reference	BB/J00989X/1
Principal Investigator / Supervisor	Professor Shankar Srinivas
Co-Investigators / Co-Supervisors
Institution	University of Oxford
Department	Physiology Anatomy and Genetics
Funding type	Research
Value (£)	509,733
Status	Completed
Type	Research Grant
Start date	01/06/2012
End date	31/10/2015
Duration	41 months

Abstract

The anterior visceral endoderm (AVE) is required for anterior-posterior axis specification in the mouse embryo. AVE cells migrate directionally within the VE, thereby properly positioning the future anterior of the embryo and orientating the primary body axis. AVE cells consistently come to an abrupt stop at the border between the anterior epiblast and extra-embryonic ectoderm, which represents an end-point to their proximal migration. Using high-resolution 3D reconstructions of protein localisation patterns and time-lapse microscopy we have shown that AVE cells move by exchanging neighbours within an intact epithelium. Cell movement and mixing is restricted to the VE overlying the epiblast, characterised by the enrichment of Dishevelled-2 (Dvl2) to the lateral plasma membrane, a hallmark of Planar Cell Polarity (PCP) signalling. AVE cells halt upon reaching the adjoining region of VE overlying the extra-embryonic ectoderm, which displays reduced neighbour exchange and in which Dvl2 is excluded specifically from the plasma membrane. Though a single continuous sheet, these two regions of VE show distinct and dynamic patterns of F-actin and myosin IIA localisation. Little is known about how surrounding cells in the VE respond to or influence AVE migration and the significance of the dynamic localisation patterns of Dvl-2, F-actin and myosin IIA. This project aims to use light sheet microscopy and automated image segmentation and analysis algorithms to perform a comprehensive characterisation of VE cell behaviour in wild type embryos and various mutants with AVE migration defects. Using fluorescent reporters of F-actin and myosin IIA, we will determine the dynamics of localisation of these molecular motors. By mislocalisaing Dvl-2 in the VE, we will test hypotheses relating to the significance of its specific localisation pattern.

Summary

During embryonic development, the head-tail axis is properly oriented by the migration of a special group of cells called the anterior visceral endoderm (AVE). If these cells fail to migrate, the embryo develops abnormally and generally aborts. The AVE moves within a sheet of cells called the Visceral Endoderm (VE). Work from my group indicates that AVE migration is regulated by the surrounding VE cells changing their shapes in a coordinated manner. Our work has implicated a specific molecular pathway called the Planar Cell Polarity (PCP) pathway in AVE migration. Using a novel imaging technology that provides images of living samples at extremely high quality, this project will characterise in detail the movement of all the cells of the VE, to provide the contexts in which to understand AVE migration. It will also characterise the dynamics of the molecular motors that drive the cell shape changes that regulate AVE migration. To better understand the influence of PCP signaling on AVE migration, we will disrupt it in various way, to determine what effect this has on AVE migration. We will examine various mutants that are known to show a failure of AVE migration to see if they also show a perturbation of PCP molecules. Finally, we will examine mutants of major PCP genes for AVE migration defects. Sheets of cells like the VE are generically called epithelia and play an important part in many developmental processes. In adults, epithelia give rise to the majority of cancers, and the spreading of such tumors is the major cause of mortality in patients. PCP signaling is important in many contexts, such as during the formation of the heart and spinal cord. Disruption of PCP can lead to congenital heart defects or condition such as spina bifida, where portions of the spinal cord are exposed through the skin on the back of the body. A better understanding of both epithelia and PCP signaling will contribute to the development of treatments for pathological conditions arising from their perturbation.

Impact Summary

The results of this research will be conveyed to other researchers through the publication of findings in peer-reviewed journals, by reporting unpublished work at conferences and through personal communication with other scientists. Image data that has been converted into vector models will be made available on a publicly accessible web site. Though meant primarily for other scientist, such data will also be readily available to the general public. Though the results will primarily be disseminated through scientific journals, attempts will be made to inform the media of results prior to publication, so that the general public is more likely to be made aware of the results. The results of this project will be communicated primarily by the PI, but also by the postdoc working on the project. Manuscripts will be written by the two together. Websites making the data publicly accessible will be plain but functional. Such simple web sites can be created relatively easily with commercially available programs.

Committee	Research Committee C (Genes, development and STEM approaches to biology)
Research Topics	X – not assigned to a current Research Topic
Research Priority	X – Research Priority information not available
Research Initiative	X - not in an Initiative
Funding Scheme	X – not Funded via a specific Funding Scheme

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