title: Dictyostelium discoideum paxillin regulates actin-based processes.
abstract: Paxillin is a key player in integrating the actin cytoskeleton with adhesion, and thus is essential to numerous cellular processes, including proliferation, differentiation, and migration in animal cells. PaxB, the Dictyostelium discoideum orthologue of paxillin, has been shown to be important for adhesion and development, much like its mammalian counterpart. Here, we use the overproduction of PaxB to gain better insight into its role in regulating the actin cytoskeleton and adhesion. We find that PaxB-overexpressing (PaxBOE) cells can aggregate and form mounds normally, but are blocked in subsequent development. This arrest can be rescued by addition of wild-type cells, indicating a non-cell autonomous role for PaxB. PaxBOE cells also have alterations in several actin-based processes, including adhesion, endocytosis, motility, and chemotaxis. PaxBOE cells exhibit an EDTA-sensitive increase in cell-cell cohesion, suggesting that PaxB-mediated adhesion is Ca(2+) or Mg(2+) dependent. Interestingly, cells overexpressing paxB are less adhesive to the substratum. In addition, PaxBOE cells display decreased motility under starved conditions, decreased endocytosis, and are unable to efficiently chemotax up a folate gradient. Taken together, the data suggest that proper expression of PaxB is vital for the regulation of development and actin-dependent processes.
authors.affiliation: Department of Biological Sciences, Center for the Study of Gene Structure and Function, Hunter College of the City University of New York, New York, NY 10021, USA.
authors.forename: M Berenice
authors.initials: MB
authors.lastname: Duran
authors.forename: Asif
authors.initials: A
authors.lastname: Rahman
authors.forename: Max
authors.initials: M
authors.lastname: Colten
authors.forename: Derrick
authors.initials: D
authors.lastname: Brazill
mesh_terms: D000199:Actins / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D002448:Cell Adhesion; D002633:Chemotaxis; D003599:Cytoskeleton / Q000235:genetics / Q000378:metabolism; D004023:Dictyostelium / Q000235:genetics / Q000254:growth & development / Q000502:physiology*; D004705:Endocytosis; D015870:Gene Expression; D051419:Paxillin / Q000235:genetics / Q000378:metabolism*; D015800:Protozoan Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D000199:Actins; D051419:Paxillin; D015800:Protozoan Proteins