Regulated and polarized PtdIns(3,4,5)P3 accumulation is essential for apical membrane morphogenesis in photoreceptor epithelial cells.
BACKGROUND
In a specialized epithelial cell such as the Drosophila photoreceptor, a conserved set of proteins is essential for the establishment of polarity, its maintenance, or both--in Drosophila, these proteins include the apical factors Bazooka, D-atypical protein kinase C, and D-Par6 together with D-Ecadherin. However, little is known about the mechanisms by which such apical factors might regulate the differentiation of the apical membrane into functional domains such as an apical-most stack of microvilli or more lateral sub-apical membrane.


RESULTS
We show that in photoreceptors Bazooka (D-Par3) recruits the tumor suppressor lipid phosphatase PTEN to developing cell-cell junctions (Zonula Adherens, za). za-localized PTEN controls the spatially restricted accumulation of optimum levels of the lipid PtdIns(3,4,5)P3 within the apical membrane domain. This in turn finely tunes activation of Akt1, a process essential for proper morphogenesis of the light-gathering organelle, consisting of a stack of F-actin rich microvilli within the apical membrane.


CONCLUSIONS
Spatially localized PtdIns(3,4,5)P3 mediates directional sensing during neutrophil and Dictyostelium chemotaxis. We conclude that a conserved mechanism also operates during photoreceptor epithelial cell morphogenesis in order to achieve normal differentiation of the apical membrane.
Pinal
Noelia
N
Medical Research Council Laboratory for Molecular Cell Biology and Cell Biology Unit, Department of Anatomy and Developmental Biology, University College London, Gower Street, WC1E 6BT London, United Kingdom.
Goberdhan
Deborah C I
DC
Collinson
Lucy
L
Fujita
Yasuyuki
Y
Cox
Iain M
IM
Wilson
Clive
C
Pichaud
Franck
F
D022005:Adherens Junctions / Q000378:metabolism; D000818:Animals; D002462:Cell Membrane / Q000648:ultrastructure*; D016764:Cell Polarity; D004330:Drosophila / Q000166:cytology / Q000254:growth & development* / Q000378:metabolism; D029721:Drosophila Proteins / Q000378:metabolism / Q000502:physiology*; D004847:Epithelial Cells / Q000166:cytology; D018507:Gene Expression Regulation, Developmental; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism / Q000502:physiology; D008871:Microvilli / Q000378:metabolism; D008954:Models, Biological; D009024:Morphogenesis; D051059:PTEN Phosphohydrolase / Q000378:metabolism / Q000502:physiology; D018129:Phosphatidylinositol Phosphates / Q000032:analysis / Q000378:metabolism / Q000502:physiology*; D017956:Photoreceptor Cells, Invertebrate / Q000166:cytology* / Q000254:growth & development; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism
D029721:Drosophila Proteins; D047908:Intracellular Signaling Peptides and Proteins; D018129:Phosphatidylinositol Phosphates; C400774:baz protein, Drosophila; C060974:phosphatidylinositol 3,4,5-triphosphate; D017346:Protein Serine-Threonine Kinases; D051059:PTEN Phosphohydrolase; C487101:PTEN protein, Drosophila