Research Fellows Directory
Dr Veronica Grieneisen
University of East Anglia
Understanding how symmetry breakage at the cellular level is linked to multi-cellular dynamics requires us to unravel the origin of the non-homogeneous distribution of membrane-bound proteins and cytoskeleton arrangements, which together define cell polarity. With this aim, my lab combines computational approaches with molecular studies and microscopy to understand polarity on two different levels: the cellular and the tissue level (i.e. how do cells collectively orientate themselves). For single cells, we have shown how polarity emerges spontaneously, independent of spatial pre-patterns or localized signals. Experimentally, we focused on the tantalising system of the plant pavement cells (PCs). These leaf epidermal cells undergo fascinating shape changes to take up the form of jigsaw pieces with lobes and interdigitations that interlock with their neighbours. Each lobe and interdigitation is an individual polarised structure, so these cells exhibit organised, multiple polarities. The complex, interdigitating patterns of PCs indicate that cell polarity should not be seen as a simple, downstream effect of polarising signals, but involves feedback between cell shape and patterning within an individual cell, as well as cell-cell signalling and bio-mechanical coupling between neighbouring cells. To unravel this, an integrated systems biology approach was required. We found that, being capable of intracellular partitioning, neighbouring plant cells separated by cell wall can coordinate their polarities through indirect cell-cell coupling. For PCs, this phenomenon comes about as interdigitation, and requires the opposite response of identical neighbouring cells to the same local signal in the cell wall. Our theoretical work has identified key requirements for such indirect cell-cell signalling that gives rise to correct interdigitation. These requirements, based on known molecular interactions, can now be extrapolated to other multi-cellular tissues, to understand the interdependency between cell and tissue polarity. In collaborative efforts between my lab and others, we can now also understand how animal cells, capable of direct cell-cell coupling, can establish through similar principles, such tissue coordination.
Interests and expertise (Subject groups)