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Updated: Sep 29, 2026
Live Imaging of Drosophila Larval Neuroblasts
Published on: July 7, 2014
Drosophila APC2 and APC1 have overlapping roles in the larval brain despite their distinct intracellular
Kathryn Akong1, Brooke M McCartney, Mark Peifer
1Curriculum in Genetics and Molecular Biology, University of North Carolina, Chapel Hill, North Carolina 27599-3280, USA.
Abstract:
The tumor suppressor APC and its homologs, first identified for a role in colon cancer, negatively regulate Wnt signaling in both oncogenesis and normal development, and play Wnt-independent roles in cytoskeletal regulation. Both Drosophila and mammals have two APC family members. We further explored the functions of the Drosophila APCs using the larval brain as a model. We found that both proteins are expressed in the brain. APC2 has a highly dynamic, asymmetric localization through the larval neuroblast cell cycle relative to known mediators of embryonic neuroblast asymmetric divisions. Adherens junction proteins also are asymmetrically localized in neuroblasts. In addition they accumulate with APC2 and APC1 in nerves formed by axons of the progeny of each neuroblast-ganglion mother cell cluster. APC2 and APC1 localize to very different places when expressed in the larval brain: APC2 localizes to the cell cortex and APC1 to centrosomes and microtubules. Despite this, they play redundant roles in the brain; while each single mutant is normal, the zygotic double mutant has severely reduced numbers of larval neuroblasts. Our experiments suggest that this does not result from misregulation of Wg signaling, and thus may involve the cytoskeletal or adhesive roles of APC proteins.
Insights
The Adenomatous Polyposis Coli (APC) proteins, APC1 and APC2, have redundant roles in the Drosophila larval brain. Loss of both APC proteins severely reduces neuroblast numbers, suggesting cytoskeletal or adhesive functions.
Area of Science:
- Developmental Biology
- Cell Biology
- Cancer Research
Background:
- The tumor suppressor Adenomatous Polyposis Coli (APC) and its homologs are crucial for regulating Wnt signaling in development and oncogenesis.
- APC proteins also play Wnt-independent roles in cytoskeletal regulation.
- Drosophila and mammals possess two APC family members, with their specific functions in the larval brain being underexplored.
Purpose of the Study:
- To investigate the functions of the two Drosophila APC proteins (APC1 and APC2) in the larval brain.
- To determine the localization and cellular roles of APC1 and APC2 during neuroblast cell cycles and axon formation.
Main Methods:
- Utilized the Drosophila larval brain as a model system to study APC protein function.
- Examined the expression patterns and subcellular localization of APC1 and APC2 during neuroblast divisions and in developing nerves.
- Generated single and double mutants for APC1 and APC2 to assess their roles in neuroblast proliferation.
Main Results:
- Both APC1 and APC2 are expressed in the larval brain, with APC2 exhibiting dynamic, asymmetric localization during the neuroblast cell cycle.
- APC proteins, along with adherens junction proteins, accumulate in nerves formed by neuroblast progeny.
- While APC2 localizes to the cell cortex and APC1 to centrosomes/microtubules, they exhibit redundant functions, as the double mutant shows a severe reduction in larval neuroblasts.
Conclusions:
- Drosophila APC1 and APC2 play essential, redundant roles in maintaining larval neuroblast numbers.
- The observed neuroblast reduction in double mutants is likely due to APCs' roles in cytoskeletal regulation or cell adhesion, rather than Wnt signaling misregulation.
