Carl Laflamme

Université de Montréal, Montréal, Quebec, Canada

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Publications (3)30.8 Total impact

  • Carl Laflamme · Gregory Emery
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    ABSTRACT: Small GTPases of the Rab family are master regulators of vesicular trafficking. As such, they control the spatial distribution of various proteins, including proteins involved in cell signaling and the regulation of cell polarity. Misregulation of Rab proteins is associated with a large array of diseases. Surprisingly, the target of some key regulators of Rab proteins, including many GTPase-activating protein (GAP) is still unknown. Identifying the target of a specific GAP requires the combination of both in vitro and in vivo experiments to avoid any misinterpretation. Here is described the methodology we used to characterize the Rab11-GAP activity of Drosophila Evi5. We first focus on the in vitro Rab11 effector pull-down assay we developed and then we detail the in vivo characterization of Rab11 activity during Drosophila border cell migration.
    No preview · Article · Mar 2015 · Methods in molecular biology (Clifton, N.J.)
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    ABSTRACT: Collective cell movements contribute to development and metastasis. The small GTPase Rac is a key regulator of actin dynamics and cell migration but the mechanisms that restrict Rac activation and localization in a group of collectively migrating cells are unknown. Here, we demonstrate that the small GTPases Rab5 and Rab11 regulate Rac activity and polarization during collective cell migration. We use photoactivatable forms of Rac to demonstrate that Rab11 acts on the entire group to ensure that Rac activity is properly restricted to the leading cell through regulation of cell-cell communication. In addition, we show that Rab11 binds to the actin cytoskeleton regulator Moesin and regulates its activation in vivo during migration. Accordingly, reducing the level of Moesin activity also affects cell-cell communication, whereas expressing active Moesin rescues loss of Rab11 function. Our model suggests that Rab11 controls the sensing of the relative levels of Rac activity in a group of cells, leading to the organization of individual cells in a coherent multicellular motile structure.
    Full-text · Article · Feb 2013 · Nature Cell Biology
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    ABSTRACT: Membrane trafficking has well-defined roles during cell migration. However, its regulation is poorly characterized. In this paper, we describe the first screen for putative Rab-GTPase-activating proteins (GAPs) during collective cell migration of Drosophila melanogaster border cells (BCs), identify the uncharacterized Drosophila protein Evi5 as an essential membrane trafficking regulator, and describe the molecular mechanism by which Evi5 regulates BC migration. Evi5 requires its Rab-GAP activity to fulfill its functions during migration and acts as a GAP protein for Rab11. Both loss and gain of Evi5 function blocked BC migration by disrupting the Rab11-dependent polarization of active guidance receptors. Altogether, our findings deepen our understanding of the molecular machinery regulating endocytosis and subsequently cell signaling during migration.
    Full-text · Article · Jul 2012 · The Journal of Cell Biology