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The Abl/enabled signaling pathway regulates Golgi architecture in Drosophila photoreceptor neurons.

Kannan R, Kuzina I, Wincovitch S, Nowotarski SH, Giniger E - Mol. Biol. Cell (2014)

Bottom Line: The Abl effector, Enabled (Ena), selectively labels the cis-Golgi in developing PRs.Finally, we demonstrate that the effects of Abl signaling on Golgi are mediated via regulation of the actin cytoskeleton.Moreover, they raise the possibility that some of the effects of Abl signaling may arise, in part, from alterations of protein trafficking and secretion.

View Article: PubMed Central - PubMed

Affiliation: Axon Guidance and Neural Connectivity Unit, Basic Neuroscience Program, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892.

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Abl regulates fusion and fission of Golgi fragments in larval photoreceptor neurons. (A, B) Representative single Z-slices acquired during live imaging of Golgi dynamics in third-instar larval PR neurons, using an α-mannosidase-eGFP reporter. Examples of fusion events are circled in green; examples of fission events are circled in purple. Images were obtained by spinning disk confocal microscopy, with images collected every 0.65 s over an imaging period. Scaling per pixel: 0.21 × 0.21 × 1 μm. Note that individual cisternae move in or out of the plane of focus at some time points. (A) Wild type. (B) Abl mutant (Df stJ7/abl4). For additional data, see also Supplemental Movies S1 and S2. (C) Quantification of fission and fusion events over a 15.6-s time period in one PR cluster in WT and Abl mutants. Statistical significance evaluated by ANOVA. **p < 0.001. Error bars represent SEM. Note that the histogram presents the number of Golgi cisternae per PR cluster, not per cell.
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Figure 5: Abl regulates fusion and fission of Golgi fragments in larval photoreceptor neurons. (A, B) Representative single Z-slices acquired during live imaging of Golgi dynamics in third-instar larval PR neurons, using an α-mannosidase-eGFP reporter. Examples of fusion events are circled in green; examples of fission events are circled in purple. Images were obtained by spinning disk confocal microscopy, with images collected every 0.65 s over an imaging period. Scaling per pixel: 0.21 × 0.21 × 1 μm. Note that individual cisternae move in or out of the plane of focus at some time points. (A) Wild type. (B) Abl mutant (Df stJ7/abl4). For additional data, see also Supplemental Movies S1 and S2. (C) Quantification of fission and fusion events over a 15.6-s time period in one PR cluster in WT and Abl mutants. Statistical significance evaluated by ANOVA. **p < 0.001. Error bars represent SEM. Note that the histogram presents the number of Golgi cisternae per PR cluster, not per cell.

Mentions: Live imaging of Golgi biogenesis using a Golgi marker, α-mannosidase II-eGFP, revealed that Abl controls the dynamics of Golgi fusion and fission events in vivo (Figure 5, A– C, and Supplemental Movies S1 and S2). In wild-type PR neurons, small clusters consisting of vesicular and tubular-shaped Golgi structures were present throughout the cell. They were highly dynamic and exhibited stochastic movement in both apical and basal directions. We also observed selective fusion of neighboring vesicular structures, eventually leading to the formation of tubular-shaped Golgi, as well as to fission of preexisting Golgi structures (Figure 5A and Supplemental Movie S1). Fusion and fission events were not synchronous for all Golgi structures in the same cell. In Abl mutants (Figure 5B and Supplemental Movie S2), Golgi exhibit restricted movement compared with the dynamics observed in wild type (Figure 5A), with Golgi puncta staying more aggregated in the vicinity of their neighbors. Moreover, counting fission and fusion events revealed a significant increase in fission and decrease in fusion of Golgi fragments per unit time in Abl mutants compared with wild type. In WT eye disks, we observed 3.6 ± 0.8 apparent fission events and 4.9 ± 0.3 fusion events per PR cluster per 15.6-s observation period (as assessed morphologically, at the resolution of spinning disk confocal imaging). In contrast, Abl mutants showed 6.8 ± 0.4 apparent fission events (p = 1.8E-07) and 2.4 ± 0.9 fusion events per cluster (p = 2.1E-08). Thus it appears that Abl activity promotes fusion and limits fission of Golgi fragments in PR neurons (Figure 5C).


The Abl/enabled signaling pathway regulates Golgi architecture in Drosophila photoreceptor neurons.

Kannan R, Kuzina I, Wincovitch S, Nowotarski SH, Giniger E - Mol. Biol. Cell (2014)

Abl regulates fusion and fission of Golgi fragments in larval photoreceptor neurons. (A, B) Representative single Z-slices acquired during live imaging of Golgi dynamics in third-instar larval PR neurons, using an α-mannosidase-eGFP reporter. Examples of fusion events are circled in green; examples of fission events are circled in purple. Images were obtained by spinning disk confocal microscopy, with images collected every 0.65 s over an imaging period. Scaling per pixel: 0.21 × 0.21 × 1 μm. Note that individual cisternae move in or out of the plane of focus at some time points. (A) Wild type. (B) Abl mutant (Df stJ7/abl4). For additional data, see also Supplemental Movies S1 and S2. (C) Quantification of fission and fusion events over a 15.6-s time period in one PR cluster in WT and Abl mutants. Statistical significance evaluated by ANOVA. **p < 0.001. Error bars represent SEM. Note that the histogram presents the number of Golgi cisternae per PR cluster, not per cell.
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Related In: Results  -  Collection

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Figure 5: Abl regulates fusion and fission of Golgi fragments in larval photoreceptor neurons. (A, B) Representative single Z-slices acquired during live imaging of Golgi dynamics in third-instar larval PR neurons, using an α-mannosidase-eGFP reporter. Examples of fusion events are circled in green; examples of fission events are circled in purple. Images were obtained by spinning disk confocal microscopy, with images collected every 0.65 s over an imaging period. Scaling per pixel: 0.21 × 0.21 × 1 μm. Note that individual cisternae move in or out of the plane of focus at some time points. (A) Wild type. (B) Abl mutant (Df stJ7/abl4). For additional data, see also Supplemental Movies S1 and S2. (C) Quantification of fission and fusion events over a 15.6-s time period in one PR cluster in WT and Abl mutants. Statistical significance evaluated by ANOVA. **p < 0.001. Error bars represent SEM. Note that the histogram presents the number of Golgi cisternae per PR cluster, not per cell.
Mentions: Live imaging of Golgi biogenesis using a Golgi marker, α-mannosidase II-eGFP, revealed that Abl controls the dynamics of Golgi fusion and fission events in vivo (Figure 5, A– C, and Supplemental Movies S1 and S2). In wild-type PR neurons, small clusters consisting of vesicular and tubular-shaped Golgi structures were present throughout the cell. They were highly dynamic and exhibited stochastic movement in both apical and basal directions. We also observed selective fusion of neighboring vesicular structures, eventually leading to the formation of tubular-shaped Golgi, as well as to fission of preexisting Golgi structures (Figure 5A and Supplemental Movie S1). Fusion and fission events were not synchronous for all Golgi structures in the same cell. In Abl mutants (Figure 5B and Supplemental Movie S2), Golgi exhibit restricted movement compared with the dynamics observed in wild type (Figure 5A), with Golgi puncta staying more aggregated in the vicinity of their neighbors. Moreover, counting fission and fusion events revealed a significant increase in fission and decrease in fusion of Golgi fragments per unit time in Abl mutants compared with wild type. In WT eye disks, we observed 3.6 ± 0.8 apparent fission events and 4.9 ± 0.3 fusion events per PR cluster per 15.6-s observation period (as assessed morphologically, at the resolution of spinning disk confocal imaging). In contrast, Abl mutants showed 6.8 ± 0.4 apparent fission events (p = 1.8E-07) and 2.4 ± 0.9 fusion events per cluster (p = 2.1E-08). Thus it appears that Abl activity promotes fusion and limits fission of Golgi fragments in PR neurons (Figure 5C).

Bottom Line: The Abl effector, Enabled (Ena), selectively labels the cis-Golgi in developing PRs.Finally, we demonstrate that the effects of Abl signaling on Golgi are mediated via regulation of the actin cytoskeleton.Moreover, they raise the possibility that some of the effects of Abl signaling may arise, in part, from alterations of protein trafficking and secretion.

View Article: PubMed Central - PubMed

Affiliation: Axon Guidance and Neural Connectivity Unit, Basic Neuroscience Program, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892.

Show MeSH
Related in: MedlinePlus