scholarly journals Clathrin adaptor AP-1 and Stratum act in parallel pathways to control Notch activation in Drosophila Sensory Organ Precursor Cells

Development ◽  
2020 ◽  
pp. dev.191437
Author(s):  
Karen Bellec ◽  
Mathieu Pinot ◽  
Isabelle Gicquel ◽  
Roland Le Borgne

Drosophila sensory organ precursors divide asymmetrically to generate pIIa/pIIb cells whose identity relies on activation of Notch at cytokinesis. While 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 signaling requires appropriate apico-basal targeting of Notch, its ligand Delta and its trafficking partner Sanpodo. We previously reported that AP-1 and Stratum regulate the trafficking of Notch and Sanpodo from the trans-Golgi network to the basolateral membrane. Loss of AP-1 or Stratum caused mild Notch gain-of-function phenotypes. Here, we report that their concomitant loss results in a penetrant Notch gain-of-function phenotype indicating that they control parallel pathways. While unequal partitioning of cell fate determinants and cell polarity were unaffected, we observed increased amounts of signaling-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.

2020 ◽  
Author(s):  
Karen Bellec ◽  
Mathieu Pinot ◽  
Isabelle Gicquel ◽  
Roland Le Borgne

AbstractDrosophila sensory organ precursors divide asymmetrically to generate pIIa/pIIb cells whose identity relies on the differential activation of Notch at cytokinesis. While Notch is present apically and basally relative to the midbody at the pIIa-pIIb interface, only the basal pool of Notch is reported to contribute to Notch activation in the pIIa cell. Correct intra-lineage signalling requires appropriate apico-basal targeting of Notch, its ligand Delta and its trafficking partner Sanpodo. We previously reported that AP-1 and Stratum regulate the intracellular trafficking of Notch and Sanpodo from the trans-Golgi network to the basolateral membrane. Loss of AP-1 or Stratum caused mild Notch gain-of-function phenotypes. Here, we report that the concomitant loss of AP-1 and Stratum results in a much more penetrant Notch gain-of-function phenotype indicating that AP-1 and Strat control two parallel pathways. While unequal partitioning of cell fate determinants and cell polarity were unaffected, Numb-mediated symmetry breaking is impaired. We further observed increased amounts of signaling competent Notch as well as Delta and Sanpodo at the apical pIIa-pIIb interface and the loss of the basal pool of Notch. We propose that AP-1 and Stratum operate in two parallel pathways to ensure the correct apico-basal localization of Notch controlling where receptor activation takes place.


2019 ◽  
Author(s):  
Karen Bellec ◽  
Isabelle Gicquel ◽  
Roland Le Borgne

AbstractDrosophila sensory organ precursors divide asymmetrically to generate pIIa/pIIb cells whose identity relies on the differential activation of Notch during cytokinesis. While Notch is present apically and basally relative to the midbody at the pIIa-pIIb interface, only the basal pool of Notch is reported to contribute to Notch activation in the pIIa cell. Such proper intra-lineage signalling therefore requires appropriate apico-basal targeting of Notch, its ligand Delta and its trafficking partner Sanpodo. We previously reported that AP-1 and Stratum regulate the intracellular trafficking of Notch and Sanpodo from the trans-Golgi network to basolateral membrane. Loss of AP-1 or of Stratum caused mild Notch phenotype. Here, we report that the concomitant loss of AP-1 and Stratum result in the stabilization of the apical pool of Notch, Delta and Spdo, the loss of the basal pool of Notch at the pIIa-pIIb interface, and is associated with activation of Notch in the two SOP daughters. We propose that AP-1 and Stratum control two parallel pathways towards plasma membrane and that Notch intra-lineage signalling could also occur at the apical pIIa-pIIb interface.


Genetics ◽  
1995 ◽  
Vol 141 (4) ◽  
pp. 1491-1505
Author(s):  
D F Lyman ◽  
B Yedvobnick

Abstract The neurogenic Notch locus of Drosophila encodes a receptor necessary for cell fate decisions within equivalence groups, such as proneural clusters. Specification of alternate fates within clusters results from inhibitory communication among cells having comparable neural fate potential. Genetically, Hairless (H) acts as an antagonist of most neurogenic genes and may insulate neural precursor cells from inhibition. H function is required for commitment to the bristle sensory organ precursor (SOP) cell fate and for daughter cell fates. Using Notch gain-of-function alleles and conditional expression of an activated Notch transgene, we show that enhanced signaling produces H-like loss-of-function phenotypes by suppressing bristle SOP cell specification or by causing an H-like transformation of sensillum daughter cell fates. Furthermore, adults carrying Notch gain of function and H alleles exhibit synergistic enhancement of mutant phenotypes. Over-expression of an H+ transgene product suppressed virtually all phenotypes generated by Notch gain-of-function genotypes. Phenotypes resulting from over-expression of the H+ transgene were blocked by the Notch gain-of-function products, indicating a balance between Notch and H activity. The results suggest that H insulates SOP cells from inhibition and indicate that H activity is suppressed by Notch signaling.


Genetics ◽  
2000 ◽  
Vol 155 (2) ◽  
pp. 733-752 ◽  
Author(s):  
Salim Abdelilah-Seyfried ◽  
Yee-Ming Chan ◽  
Chaoyang Zeng ◽  
Nicholas J Justice ◽  
Susan Younger-Shepherd ◽  
...  

Abstract The Drosophila adult external sensory organ, comprising a neuron and its support cells, is derived from a single precursor cell via several asymmetric cell divisions. To identify molecules involved in sensory organ development, we conducted a tissue-specific gain-of-function screen. We screened 2293 independent P-element lines established by P. Rørth and identified 105 lines, carrying insertions at 78 distinct loci, that produced misexpression phenotypes with changes in number, fate, or morphology of cells of the adult external sensory organ. On the basis of the gain-of-function phenotypes of both internal and external support cells, we subdivided the candidate lines into three classes. The first class (52 lines, 40 loci) exhibits partial or complete loss of adult external sensory organs. The second class (38 lines, 28 loci) is associated with increased numbers of entire adult external sensory organs or subsets of sensory organ cells. The third class (15 lines, 10 loci) results in potential cell fate transformations. Genetic and molecular characterization of these candidate lines reveals that some loci identified in this screen correspond to genes known to function in the formation of the peripheral nervous system, such as big brain, extra macrochaetae, and numb. Also emerging from the screen are a large group of previously uncharacterized genes and several known genes that have not yet been implicated in the development of the peripheral nervous system.


2010 ◽  
Vol 21 (12) ◽  
pp. 2078-2086 ◽  
Author(s):  
Najate Benhra ◽  
Françoise Vignaux ◽  
Aurore Dussert ◽  
François Schweisguth ◽  
Roland Le Borgne

Notch receptors mediate short-range signaling controlling many developmental decisions in metazoans. Activation of Notch requires the ubiquitin-dependent endocytosis of its ligand Delta. How ligand endocytosis in signal-sending cells regulates receptor activation in juxtaposed signal-receiving cells remains largely unknown. We show here that a pool of Delta localizes at the basolateral membrane of signal-sending sensory organ precursor cells in the dorsal thorax neuroepithelium of Drosophila and that Delta is endocytosed in a Neuralized-dependent manner from this basolateral membrane. This basolateral pool of Delta is segregated from Notch that accumulates apically. Using a compartimentalized antibody uptake assay, we show that murine Delta-like 1 is similarly internalized by mNeuralized2 from the basolateral membrane of polarized Madin-Darby canine kidney cells and that internalized ligands are transcytosed to the apical plasma membrane where mNotch1 accumulates. Thus, endocytosis of Delta by Neuralized relocalizes Delta from the basolateral to the apical membrane domain. We speculate that this Neuralized-dependent transcytosis regulates the signaling activity of Delta by relocalizing Delta from a membrane domain where it cannot interact with Notch to another membrane domain where it can bind and activate Notch.


Development ◽  
1995 ◽  
Vol 121 (11) ◽  
pp. 3745-3752 ◽  
Author(s):  
V. Jennings ◽  
J. de Celis ◽  
C. Delidakis ◽  
A. Preiss ◽  
S. Bray

The proteins encoded by Notch and the Enhancer of split complex are components of a cell-cell interaction mechanism which is important in many cell fate decisions throughout development. One such decision is the formation of the sensory organ precursor cell during the development of the peripheral nervous system in Drosophila. Cells acquire the potential to be neural through the expression of the proneural genes, and the Notch pathway is required to limit neural fate to a single cell from a proneural cluster. However, despite extensive analysis, the precise pathways linking the proneural with Notch and Enhancer of split gene functions remain obscure. For example, it has been suggested that achaete-scute complex proteins directly activate Enhancer of split genes leaving the action of Notch in the pathway unclear. Using monoclonal antibodies that recognise products of the Enhancer of split complex, we show that these proteins accumulate in the cells surrounding the developing sensory organ precursor cell and that their expression is dependent on the activity of Notch and does not directly correlate with expression of Achaete. We further clarify the pathway by showing that ubiquitous expression of an activated Notch receptor leads to widespread accumulation of Enhancer of split proteins even in the absence of achaete-scute complex proteins. Thus Enhancer of split protein expression in response to Notch activity does not require achaete-scute complex proteins.


2013 ◽  
Vol 201 (3) ◽  
pp. 439-448 ◽  
Author(s):  
Alok Upadhyay ◽  
Vasundhara Kandachar ◽  
Diana Zitserman ◽  
Xin Tong ◽  
Fabrice Roegiers

In Drosophila peripheral neurogenesis, Notch controls cell fates in sensory organ precursor (SOP) cells. SOPs undergo asymmetric cell division by segregating Numb, which inhibits Notch signaling, into the pIIb daughter cell after cytokinesis. In contrast, in the pIIa daughter cell, Notch is activated and requires Sanpodo, but its mechanism of action has not been elucidated. As Sanpodo is present in both pIIa and pIIb cells, a second role for Sanpodo in regulating Notch signaling in the low-Notch pIIb cell has been proposed. Here we demonstrate that Sanpodo regulates Notch signaling levels in both pIIa and pIIb cells via distinct mechanisms. The interaction of Sanpodo with Presenilin, a component of the γ-secretase complex, was required for Notch activation and pIIa cell fate. In contrast, Sanpodo suppresses Notch signaling in the pIIb cell by driving Notch receptor internalization. Together, these results demonstrate that a single protein can regulate Notch signaling through distinct mechanisms to either promote or suppress signaling depending on the local cellular context.


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