title: Xenopus p21-activated kinase 5 regulates blastomeres' adhesive properties during convergent extension movements.
abstract: The p21-activated kinase (PAK) proteins regulate many cellular events including cell cycle progression, cell death and survival, and cytoskeleton rearrangements. We previously identified X-PAK5 that binds the actin and microtubule networks, and could potentially regulate their coordinated dynamics during cell motility. In this study, we investigated the functional importance of this kinase during gastrulation in Xenopus. X-PAK5 is mainly expressed in regions of the embryo that undergo extensive cell movements during gastrula such as the animal hemisphere and the marginal zone. Expression of a kinase-dead mutant inhibits convergent extension movements in whole embryos and in activin-treated animal cap by modifying behavior of cells. This phenotype is rescued in embryo by adding back X-PAK5 catalytic activity. The active kinase decreases cell adhesiveness when expressed in animal hemisphere and inhibits the calcium-dependent reassociation of cells, while dead X-PAK5 kinase localizes to cell-cell junctions and increases cell adhesion. In addition, endogenous X-PAK5 colocalizes with adherens junction proteins and its activity is regulated by extracellular calcium. Taken together, our results suggest that X-PAK5 regulates convergent extension movements in vivo by modulating the calcium-mediated cell-cell adhesion.
authors.affiliation: Centre de Recherches en Biochimie Macromoléculaire, FRE 2593 CNRS, 34293 Montpellier, France.
authors.forename: Sandrine
authors.initials: S
authors.lastname: Faure
authors.forename: Julien
authors.initials: J
authors.lastname: Cau
authors.forename: Pascal
authors.initials: P
authors.lastname: de Santa Barbara
authors.forename: Stéphanie
authors.initials: S
authors.lastname: Bigou
authors.forename: Qingyuan
authors.initials: Q
authors.lastname: Ge
authors.forename: Claude
authors.initials: C
authors.lastname: Delsert
authors.forename: Nathalie
authors.initials: N
authors.lastname: Morin
mesh_terms: D022005:Adherens Junctions / Q000378:metabolism; D000818:Animals; D001757:Blastomeres / Q000378:metabolism*; D015153:Blotting, Western; D002118:Calcium / Q000378:metabolism; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D002448:Cell Adhesion / Q000502:physiology*; D002465:Cell Movement / Q000502:physiology*; D044127:Epigenesis, Genetic; D005260:Female; D005455:Fluorescent Antibody Technique; D015870:Gene Expression; D007150:Immunohistochemistry; D047468:Immunoprecipitation; D017403:In Situ Hybridization; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D014981:Xenopus / Q000196:embryology* / Q000378:metabolism; D029867:Xenopus Proteins / Q000378:metabolism*; D001616:beta-Galactosidase; D054462:p21-Activated Kinases
chemical_list: D029867:Xenopus Proteins; D017346:Protein Serine-Threonine Kinases; C486709:X-PAK5 protein, Xenopus; D054462:p21-Activated Kinases; D001616:beta-Galactosidase; D053148:Caspase 3; D020169:Caspases; D002118:Calcium