Article abstract
Nature Cell Biology 11, 815 - 824 (2009)
Published online: 21 June 2009 | doi:10.1038/ncb1888
The Arp2/3 complex and WASp are required for apical trafficking of Delta into microvilli during cell fate specification of sensory organ precursors
Akhila Rajan1,5,7, An-Chi Tien2,6,7, Claire M. Haueter3, Karen L. Schulze3 & Hugo J. Bellen1,2,3,4
Abstract
Cell fate decisions mediated by the Notch signalling pathway require direct cell–cell contact between adjacent cells. In Drosophila melanogaster, an external sensory organ (ESO) develops from a single sensory organ precursor (SOP) and its fate specification is governed by differential Notch activation. Here we show that mutations in actin-related protein-3 (Arp3) compromise Notch signalling, leading to a fate transformation of the ESO. Our data reveal that during ESO fate specification, most endocytosed vesicles containing the ligand Delta traffic to a prominent apical actin-rich structure (ARS) formed in the SOP daughter cells. Using immunohistochemistry and transmission electron microscopy (TEM) analyses, we show that the ARS contains numerous microvilli on the apical surface of SOP progeny. In Arp2/3 and WASp mutants, the surface area of the ARS is substantially reduced and there are significantly fewer microvilli. More importantly, trafficking of Delta-positive vesicles from the basal area to the apical portion of the ARS is severely compromised. Our data indicate that WASp-dependent Arp2/3 actin polymerization is crucial for apical presentation of Delta, providing a mechanistic link between actin polymerization and Notch signalling.
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA.
- Program in Developmental Biology, Baylor College of Medicine, Houston, TX 77030, USA.
- Howard Hughes Medical Institute, Baylor College of Medicine, Houston, TX 77030, USA.
- Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA.
- Current address: Department of Genetics, Harvard Medical School, Boston, MA 021155, USA.
- Current address: University of California, San Francisco, CA 94143, USA.
- These authors contributed equally to the work.
Correspondence to: Hugo J. Bellen1,2,3,4 e-mail: hbellen@bcm.tmc.edu
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