S03-02. From cell mechanics to tissue morphogenesis

MECHANISMS OF DEVELOPMENT

1 2 6 ( 2 0 0 9 ) S 4 –S 5

available at www.sciencedirect.com

journal homepage: www.elsevier.com/locate/modo

Symposium – Mechanisms of morphogenesis S03-01

To that end we develop a range of approaches, from the

Planar cell polarity: Linking developmental regulatory mecha-

genetic and pharmacological perturbations of molecular compo-

nisms to basic cellular machinery during morphogenesis

nents, the quantitative imaging of proteins using a variety of pho-

John Wallingford1, Ryan Gray1, Tae Joo Park1, Philip Abitua1,

tonic methods, probing of the physical properties of cells within

Su Kyoung Kim1, Srimoyee Ghosh1, Edward Marcotte1,

intact tissues, and predictive computational modelling of mor-

Bogdan Wlodarczyk2, Rick Finnell2

phogenesis at different scales (molecular to tissue scales) with

1

University of Texas at Austin, Austin, TX, USA

two close collaborators (PF. Lenne and Ed. Munro).

2

Texas A&M University, Houston, TX, USA The planar cell polarity (PCP) signaling pathway is essential for

a wide variety of cell- and tissue-level morphogenetic events in developing embryos. PCP research has been predominantly directed at the role played by a small number of core proteins, including Dishevelled and Frizzled. Much less is known about how these proteins signal downstream to direct the execution of such diverse cell behaviors as convergent extension and ciliogenesis. We have focused recently on the downstream PCP effector pro-

I will present our current research characterizing how adhesion and cortical tension regulate the dynamic remodelling of cell contacts in the primary epithelium of Drosophila embryos. I will first focus on how actin controls E-cadherin organization and how E-cadherin–actin interactions control force transmission at cell interfaces. I will also report new findings concerning the spatial distributions of tensions in epithelial cells and how regulation of different tensile networks controls cell shape and cell dynamics. doi:10.1016/j.mod.2009.06.949

teins, Fuz and Fritz. We show that Fuz is essential for ciliogenesis, but plays only a minor role in convergent extension. Combining bioinformatics with confocal and electron microscopy, we establish a central role for Fuz in membrane trafficking, showing that Fuz is essential for apical trafficking of ciliogenesis factors in ciliated cells and for exocytosis in secretory cells. Unlike Fuz, Fritz plays a major role in convergent extension. Time-lapse imaging reveals a cytoskeletal role for Fritz that is essential for the maintenance plasma membrane stability and cell shape. Together,

S03-03 High resolution live microscopy of cell motility, actin dynamics and cell-cell contacts along embryonic tissue boundaries Francois Fagotto Dept. of Biology, McGill University, Montreal, Que., Canada

these results provide novel insights into the mechanisms by which upstream developmental regulatory systems like PCP sig-

A major unresolved issue in Developmental Biology concerns

naling are linked to the basic cellular machinery during embry-

the mechanisms that regulate cell behavior, allowing complex

onic morphogenesis.

and coordinated changes in position and shape of the various cell populations, generically called ‘‘morphogenetic movements”. We

doi:10.1016/j.mod.2009.06.948

are interested in the process of tissue separation, where newly determined embryonic tissues become delimited by a boundary, across which cell mixing is prevented. We have recently developed methods to study in detail cell behavior in whole tissues

S03-02 From cell mechanics to tissue morphogenesis Thomas Lecuit University of Marseille, Marseille, France

by live fluorescence microscopy. We have achieved unprecedented high resolution imaging of the cell surface and the cell– cell adhesive contacts. We can further refine our analysis by tracking individual cells using a simple technique that produces mosaic tissues. Selective manipulation of adhesive and cytoskeletal properties of these cells allows us to test the cellular/molec-

Tissues exhibit a remarkable dual property of robustness and plasticity. This relies on unique mechanical properties of the cell

ular mechanisms involved and to test various models for cell sorting at the boundary.

cortex and on adhesive interactions between cells. Our group

Using this approach, we have investigated in the frog embryo

seeks to understand the fundamental molecular mechanisms

the boundary that delimits the forming notochord. Our data indi-

responsible for this property. This is essential to understand mor-

cate that the absence of cell mixing at the boundary does not result

phogenesis of developing embryos and organs, and is severely

from different global properties of the two adjacent tissues, as

affected in a number of disease.

proposed by the models of differential adhesion and of differential