Signaling underlying "tissue origami"
During tissue development, cells change shape and rearrange through contractions generated by the actomyosin cytoskeleton. The small GTPase Rho1 promotes these contractions by stimulating actin filament assembly and activating myosin motor proteins. During my PhD, I asked how different regions of a single epithelial cell activate Rho1 to produce distinct contractile behaviors. Using the extending lateral ectoderm of the Drosophila melanogaster embryo as a model system, I showed that two separate signaling pathways control Rho1 activity: RhoGEF2 activates pulsatile contractions in the medial-apical compartment of the cell, whereas Dp114RhoGEF activates Rho1 at cell junctions, where it promotes cell intercalation by supporting junctional shrinkage. Both RhoGEFs are governed by upstream GPCRs. These results reveal how cells spatially organize contractility to drive coordinated tissue remodeling.
1. Garcia de las Bayonas A, Philippe JM, Lellouch AC, Lecuit T. Distinct RhoGEFs activate apical and junctional actomyosin contractility under control of G proteins during epithelial morphogenesis. Curr. Bio. 2019 Sep 29 (20):3370-3385. [link]
2. Kerridge S, Munjal A, Philippe JM, Jha A, Garcia de las Bayonas A, Saurin AJ and Lecuit T. Modular activation of Rho1 by GPCR signaling imparts polarized myosin II activation during morphogenesis. Nat Cell Bio. 2016 Mar 18(3):261-70 [link]