The serine/threonine kinase dPak is required for polarized assembly of F-actin bundles and apical-basal polarity in the Drosophila follicular epithelium.
During epithelial development cells become polarized along their apical-basal axis and some epithelia also exhibit polarity in the plane of the tissue. Mutations in the gene encoding a Drosophila Pak family serine/threonine kinase, dPak, disrupt the follicular epithelium that covers developing egg chambers during oogenesis. The follicular epithelium normally exhibits planar polarized organization of basal F-actin bundles such that they lie perpendicular to the anterior-posterior axis of the egg chamber, and requires contact with the basement membrane for apical-basal polarization. During oogenesis, dPak becomes localized to the basal end of follicle cells and is required for polarized organization of the basal actin cytoskeleton and for epithelial integrity and apical-basal polarity. The receptor protein tyrosine phosphatase Dlar and integrins, all receptors for extracellular matrix proteins, are required for polarization of the basal F-actin bundles, and for correct dPak localization in follicle cells. dpak mutant follicle cells show increased beta(Heavy)-spectrin levels, and we speculate that dPak regulation of beta(Heavy)-spectrin, a known participant in the maintenance of membrane domains, is required for correct apical-basal polarization of the membrane. We propose that dPak mediates communication between the basement membrane and intracellular proteins required for polarization of the basal F-actin and for apical-basal polarity.
Conder
Ryan
R
Department of Molecular Biology and Biochemistry, Simon Fraser University, 8888 University Drive, Burnaby, BC, Canada V5A 1S6.
Yu
Hong
H
Zahedi
Baharak
B
Harden
Nicholas
N
D000199:Actins / Q000378:metabolism*; D000818:Animals; D001485:Basement Membrane / Q000201:enzymology / Q000378:metabolism; D016764:Cell Polarity / Q000235:genetics / Q000502:physiology*; D002999:Clone Cells; D029721:Drosophila Proteins / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D004331:Drosophila melanogaster / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D004848:Epithelium / Q000201:enzymology / Q000254:growth & development / Q000378:metabolism; D005260:Female; D006801:Humans; D006080:Ovarian Follicle / Q000201:enzymology* / Q000254:growth & development / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D054462:p21-Activated Kinases
D000199:Actins; D029721:Drosophila Proteins; C099277:Pak protein, Drosophila; D017346:Protein Serine-Threonine Kinases; D054462:p21-Activated Kinases