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Identifying mechanisms of cell extrusions during tissue development

Primary Supervisor: Dr Michael Smutny, Warwick Medical School

Secondary supervisor: Andrew McAinsh

PhD project title: Identifying mechanisms of cell extrusions during tissue development

University of Registration: University of Warwick

Project outline:


Tissues are shaped by complex cellular processes including cell divisions, extrusions, movements, shape changes and differentiation. These events are usually controlled by biochemical molecules and physical forces that act locally or globally to trigger precise reactions at a specific time during development.

Extensive cellular rearrangements in growing tissues require control mechanisms that ensure a balanced number of cells to avoid overcrowding and enforce tissue homeostasis by expelling dying or unwanted cells [1]. Extrusion of live or apoptotic cells is controlled by various mechanisms that can actively eliminate cells from tissues including mechanical forces, cell-cell adhesions, short-range cell-cell interactions (cell competition), or geometrically induced topological defects [2-5]. Cell extrusion can in turn contribute to processes such as cell differentiation, produce morphogenetic forces and induce epithelial-to-mesenchymal transition (EMT) and thereby control developmental programs [1]. Notably, dysregulated cell extrusion impacts on functional tissue homeostasis which negatively impacts on organismal health including anoikis resistance, EMT and human cancers [3].

We recently observed patterned extrusion events of progenitor cells during the formation of the zebrafish neural plate (NP), a tissue that gives rise to the central nervous system (CNS) in vertebrates. Although the NP undergoes extensive cellular rearrangements during this developmental time, it is yet unclear what mechanisms cause extrusions and what are the consequence of these cell eliminations for tissue development.


The first objective of the project is to study molecular, cellular and physical mechanisms regulating cell elimination in the zebrafish NP tissue. The second objective is to investigate the downstream effect of cell extrusions by identifying how extrusion impacts on processes that shape and pattern the NP tissue.


The lab is using interdisciplinary approaches at the interface of biology, chemistry, physics and engineering in collaboration with other labs. This includes techniques such as in vivo live cell imaging (confocal, 2-photon, light sheet microscopy), quantitative/computational image analysis (Fiji, Matlab), molecular cloning and biochemistry assays (western blot, immunoprecipitation), gene editing (Crispr/Cas9) and biophysical tools to measure cell and tissue mechanics. Further we reconstruct 3D multicellular tissues in culture to observe self-organization of progenitor cells in vitro.


  1. Ohsawa S et al. 2018. Developmental Cell.
  2. Villars A & Levayer R. 2016. Current Biology.
  3. Eisenhoffer GT et al. 2012. Nature.
  4. Marinari E et al. 2012 Nature.
  5. Saw TB et al. 2017. Nature.
  6. Salttum GS & Rosenblatt J. 2014. Nature Review Cancer.

BBSRC Strategic Research Priority: Understanding the Rules of Life:Stem Cells

Techniques that will be undertaken during the project:

  • Zebrafish and embryo work: generation of transgenic and knockout lines
  • Live cell imaging and fixed specimen: confocal and multiphoton microscopy, selective plane illumination microscopy (SPIM)
  • Protein biochemistry (immunoprecipitations, western blots, apoptosis assays)
  • Genomic editing using Crispr/Cas9
  • In vitro reconstitution of 3D progenitor cell culture system
  • Computational image analysis and statistics: e.g. Fiji, Matlab, R
  • Biophysical tools: laser ablation, cell/tissue confiner, microstretch device

Contact: Dr Michael Smutny, University of Warwick