Antagonistic regulation by insulin-like peptide and activin ensures the elaboration of appropriate dendritic field sizes of amacrine neurons
- Section on Neuronal Connectivity, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, United States
- Institute of Cellular and Organismic Biology, Academia Sinica, Taiwan, Republic of China
- Mathematical and Statistical Computing Laboratory, Center for Information Technology, National Institutes of Health, United States
- Institute of Chemistry, Academia Sinica, Taiwan, Republic of China
- Genome and Systems Biology Degree Program, National Taiwan University and Academia Sinica, Taiwan, Republic of China
Figures
Figure 1 with 1 supplement
Cell-autonomous TOR signaling positively regulates the dendritic field sizes of Dm8 amacrine neurons.
(A) A schematic illustration of the Drosophila peripheral visual system, including the eye and two optic neuropils, the lamina and the medulla. The chromatic photoreceptors R7 (red) and R8 (magenta) …
Figure 1—figure supplement 1
Cell fate is unaffected in Tor and Pten mutant Dm8 neurons.
(A–A') Adult wild-type Dm8 neurons express the transcription factor Dachshund (Dac). Dm8 neurons were labeled by 24F06-Gal4-driven mCD8GFP (green) and co-labeled with anti-24B10 (blue) and anti-Dac …
Figure 2 with 1 supplement
Insulin/Tor signaling positively regulates Dm8 dendrite development through SREBP.
(A–F) Insulin/Tor signaling and the downstream regulator SREBP are cell-autonomously required for normal Dm8 dendritic size and patterning. Single wild-type (A), InR273 (B), chicoFs(2)4 (C), Pi3K92EA…
Figure 2—figure supplement 1
Genetic mutations of several components in the insulin/Tor signaling cascade do not alter Dm8 dendritic field size.
(A–G) Mutation of the potential components in the insulin/Tor pathway caused no defects of Dm8 dendritic field size. Single wild-type (A), dock (B), foxo (C), rictor (D), Atg7(E), s6k (F), Thor (G), …
Figure 3 with 1 supplement
Defects in Dm8 dendritic fields caused aberrant synaptic connections with R7 photoreceptors.
(A–E) Defective dendrites of Tor, Pten and chico mutant Dm8 neurons exhibit altered membrane contacts with R7 photoreceptors, revealed by the ‘receptor-based’ version of GFP Reconstitution Across …
Figure 3—figure supplement 1
In vitro TEVC recording of GFPSP11-2xHA-Ort and its in vivo expression in wild-type and mutant Dm8 clones in adults.
(A–A”) Ort and GFPSP11::2xHA::Ort display similar efficacies in response to histamine, as measured by in vitro TEVC recording. (A–A’) Responses to 10 µM histamine at −60 mV for wild-type Ort (A) and …
Figure 4 with 1 supplement
Split-GFP tagging of insulin receptor reveals its endogenous expression pattern in the optic lobe and Dm8 dendrites.
(A–C) Schematics depict the split-GFP tagging strategy to visualize endogenous insulin receptor (InR) expression at single cell resolution. (A) Three copies of split-GFP11 (3x GFPSP11, blue) and a …
Figure 4—figure supplement 1
InR is expressed in the growth cones of photoreceptors during pupal stages.
(A–A’) Expression pattern of endogenous InR in the optic lobe of developing pupal brain at 30 hr APF visualized by anti-V5 staining (blue). InR is highly expressed in the visual system. Re, retina; …
Figure 5 with 1 supplement
DILP2 derived from L5 lamina neurons positively regulates Dm8 dendritic field elaboration.
(A) A schematic illustration showing the developmental processes of R7 and R8 photoreceptors, L5 lamina neurons and Dm8 neurons. A Dm8 neuron (purple) expands its dendritic arbors during development …
Figure 5—figure supplement 1
RNAi-mediated knockdown of dilp2 in lamina neurons caused tiling phenotype of photoreceptor R7.
(A–D) The axon terminals of R7 photoreceptors displayed tiling defects after knockdown of dilp2 by the pan-LN 9B08-Gal4, but not the L5-specific 6–60 Gal4 driver. Photoreceptors were visualized by …
Figure 6
Insulin/Tor signaling operates in parallel with Activin/Baboon signaling to control Dm8 dendritic field sizes.
(A–B) Blocking both insulin and Activin signaling in Dm8s resulted in an additive effect and highly variable dendritic field sizes. (A) An illustration depicts Tor mutant Dm8s, which receive but …
Figure 7 with 1 supplement
Dendritic growth simulation reveals the relationship between kinetic parameters and field sizes and variability.
Stochastic dendritic growth was simulated with broad branching (kb) and terminating (kt) rate parameters and the radii of the resulting dendritic fields (R95) were calculated as the distance of 95th …
Figure 7—figure supplement 1
Dendritic growth simulation with different numbers of initial dendrites.
Distributions of the radii of dendritic fields of 100 neurons simulated using different numbers of initial dendrites and the parameters for the wild-type Tm20 neuron (kb = 0.360 μm−1 and kt = 0.594 …
Figure 8
Antagonistic regulation of Dm8 dendritic field arborization by two afferent-derived factors, Activin and DILP2.
(A) Two afferent-derived factors, Activin and insulin-like peptide2 (DILP2), signal to Dm8 amacrine neurons to control their dendritic field elaboration. Activin is provided by R7 photoreceptors, …
Author response image 1
In situ hybridization of Activin of developing eye discs..
Author response image 2
Activin mRNA levels in developing R-cells (Zhang et al., 2016)..
Author response image 3
Dilp2 mRNA levels in developing lamina..
Additional files
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Source code 1
Simulation programs.
- https://cdn.elifesciences.org/articles/50568/elife-50568-code1-v1.zip
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Supplementary file 1
Summary of experimental genotypes.
- https://cdn.elifesciences.org/articles/50568/elife-50568-supp1-v1.docx
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Supplementary file 2
Statistics.
- https://cdn.elifesciences.org/articles/50568/elife-50568-supp2-v1.docx
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Supplementary file 3
Key Resources Table.
- https://cdn.elifesciences.org/articles/50568/elife-50568-supp3-v1.docx
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Transparent reporting form
- https://cdn.elifesciences.org/articles/50568/elife-50568-transrepform-v1.pdf
