The Clathrin adaptor AP-1 and Stratum act in parallel pathways to control Notch activation in Drosophila sensory organ precursors cells

• Published in: Development (Cambridge) Vol. 148; no. 1
• Main Authors: Bellec, Karen, Pinot, Mathieu, Gicquel, Isabelle, Le Borgne, Roland
• Format: Journal Article
• Language: English
• Published: England The Company of Biologists Ltd 10-01-2021
• Subjects: Adaptor Protein Complex 1 - metabolism; Animals; Cell Lineage; Cell Nucleus - metabolism; Cell Polarity; Drosophila melanogaster - cytology; Drosophila melanogaster - metabolism; Drosophila Proteins - metabolism; Gain of Function Mutation; Guanine Nucleotide Exchange Factors - metabolism; Penetrance; Phenotype; Receptors, Notch - metabolism; Sense Organs - metabolism; Stem Cells - metabolism; AP-1; Intracellular trafficking; Notch signalling; Stratum; Asymmetric cell division
• ISSN: 1477-9129; 0950-1991; 1477-9129
• DOI: 10.1242/dev.191437

sensory organ precursors divide asymmetrically to generate pIIa/pIIb cells, the identity of which relies on activation of Notch at cytokinesis. Although Notch is present apically and basally relative to the midbody at the pIIa-pIIb interface, the basal pool of Notch is reported to be the main contributor for Notch activation in the pIIa cell. Intra-lineage signalling requires appropriate apico-basal targeting of Notch, its ligand Delta and its trafficking partner Sanpodo. We have previously reported that AP-1 and Stratum regulate the trafficking of Notch and Sanpodo from the
-Golgi network to the basolateral membrane. Loss of AP-1 or Stratum caused mild
gain-of-function phenotypes. Here, we report that their concomitant loss results in a penetrant
gain-of-function phenotype, indicating that they control parallel pathways. Although unequal partitioning of cell fate determinants and cell polarity were unaffected, we observed increased amounts of signalling-competent Notch as well as Delta and Sanpodo at the apical pIIa-pIIb interface, at the expense of the basal pool of Notch. We propose that AP-1 and Stratum operate in parallel pathways to localize Notch and control where receptor activation takes place.