Wolfram Pönisch-Deciphering the role of noise in cell shape changes during epithelial-to-mesenchymal transition; Constance Le Gloanec-Protect and provide: the dual role of the cauline leaf.

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• Constance Le Gloanec and Wolfram Pönisch
• Monday 03 June 2024, 14:30-15:30
• Online.

If you have a question about this talk, please contact Jia CHEN.

Wolfram Pönisch – Postdoc in Lab of Ewa Paluch, PDN University of Cambridge

Title: Deciphering the role of noise in cell shape changes during epithelial-to-mesenchymal transition

Abstract: The development of an organism requires sequential state transitions towards more specialised cell types. Many state transitions coincide with changes in cell shape, with emerging evidence suggesting strong feedback between shape and state. An example of transitions where state and shape are tightly coupled is epithelial-to-mesenchymal transition (EMT) which plays a crucial role in development and pathogenesis. While the changes in gene expression driving EMT have been extensively studied, the cell shape dynamics during EMT remain poorly understood.

To address this challenge, we developed a morphometric pipeline employing spherical harmonics descriptors to represent 3D cell morphodynamics in a low-dimensional morphospace quantitatively. Combining live-cell imaging with this pipeline, we characterised the cell shape trajectories associated with EMT . We inferred the underlying stochastic morphodynamics by modelling shape dynamics as a Langevin process and characterised the cell shape noise. Our findings reveal a peak in noise coinciding with a transition from epithelial to mesenchymal attractor states. Molecular perturbation experiments and mathematical modelling suggest that an increase in actin protrusivity and a decrease in membrane tension account for the cell shape noise during EMT . Together, our study suggests that EMT -associated cell spreading can be described as a transition between morphospace attractors.

Constance Le Gloanec, NUS

Title: Protect and provide: the dual role of the cauline leaf

Abstract: Plant organs have evolved diverse shapes for specialized functions despite emerging as simple protrusions at the shoot apex. Cauline leaves serve both as photosynthetic organs and protective structures for emerging floral buds. However, their growth patterns remain elusive. Here, we investigate the developmental dynamics shaping cauline leaves underlying their functional diversification from other flat organs. We show that cauline leaves display a strong delay in overall elongation as compared to juvenile leaves. Using live-imaging, we reveal that their functional divergence hinges on early modulation of the timing of cell differentiation and cellular growth rates. In contrast to rosette leaves and sepals, cell differentiation is delayed in cauline leaves, fostering extended proliferation, prolonged morphogenetic activity, and growth redistribution within the organ. Notably, cauline leaf growth is transiently suppressed during the early stages, keeping the leaf small and unfolded during the initiation of the first flowers. Our findings highlight the unique developmental timing of cauline leaves, underlying their shift from an early protective role to a later photosynthetic function.

Zoom link: Join Zoom Meeting https://cam-ac-uk.zoom.us/j/87939943699 Meeting ID: 879 3994 3699

This talk is part of the Morphogenesis Seminar Series series.

This talk is included in these lists:

• Graduate-Seminars
• Morphogenesis Seminar Series
• Online

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