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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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cis-Golgi complex is sensitive to the levels of Enabled protein. (A–C) Z-projections of confocal stacks of mature PR clusters labeled for Ena (green), cis-Golgi (GM130, red) and PR nuclei (Elav, blue). Individual PR cell bodies are traced (irregular white outlines). White boxes indicate regions shown enlarged to the right. Arrows point to Ena puncta; arrowheads point to GM130 puncta. Scale bar, 5 μm. (A) In wild type, Ena and cis-Golgi puncta are scattered throughout the cytoplasm of each PR cell body. (B) Ena overexpression relocates endogenous and expressed Ena to the basal end of PR cell body. Also note an increase in the number and accumulation of cis-Golgi cisternae in the vicinity of the accumulated Ena. Typically Ena accumulates to very high levels in one large basal punctum, whereas lower levels of Ena are detected in association with the other basal cisternae. (C) Ena loss of function (FP4-mito) increases the number of cis-Golgi cisternae throughout the PR cell body, whereas GM130 in control (AP4-mito) resembles WT (A). (D) Scheme used to quantify apicobasal distribution. Puncta were counted separately in the apical and basal halves of each photoreceptor. Data are expressed as puncta located in the basal halves of the cells as a percentage of the total. (E) Quantification of cis-Golgi fragmentation phenotypes. n is indicated on the bars; error bars represent SEM. Statistical significance by ANOVA (**p < 0.001). (F) cis-Golgi distribution in basal region of PR cell was quantified. n is indicated on the bars; error bars represent SEM. p values were calculated by ANOVA (**p < 0.001).
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Figure 2: cis-Golgi complex is sensitive to the levels of Enabled protein. (A–C) Z-projections of confocal stacks of mature PR clusters labeled for Ena (green), cis-Golgi (GM130, red) and PR nuclei (Elav, blue). Individual PR cell bodies are traced (irregular white outlines). White boxes indicate regions shown enlarged to the right. Arrows point to Ena puncta; arrowheads point to GM130 puncta. Scale bar, 5 μm. (A) In wild type, Ena and cis-Golgi puncta are scattered throughout the cytoplasm of each PR cell body. (B) Ena overexpression relocates endogenous and expressed Ena to the basal end of PR cell body. Also note an increase in the number and accumulation of cis-Golgi cisternae in the vicinity of the accumulated Ena. Typically Ena accumulates to very high levels in one large basal punctum, whereas lower levels of Ena are detected in association with the other basal cisternae. (C) Ena loss of function (FP4-mito) increases the number of cis-Golgi cisternae throughout the PR cell body, whereas GM130 in control (AP4-mito) resembles WT (A). (D) Scheme used to quantify apicobasal distribution. Puncta were counted separately in the apical and basal halves of each photoreceptor. Data are expressed as puncta located in the basal halves of the cells as a percentage of the total. (E) Quantification of cis-Golgi fragmentation phenotypes. n is indicated on the bars; error bars represent SEM. Statistical significance by ANOVA (**p < 0.001). (F) cis-Golgi distribution in basal region of PR cell was quantified. n is indicated on the bars; error bars represent SEM. p values were calculated by ANOVA (**p < 0.001).

Mentions: The number and subcellular distribution of Golgi cisternae were profoundly sensitive to the level of Ena protein (Figures 2, A– F, and 3, D and E). In WT we found 3.8 ± 1.0 cis-Golgi cisternae (GM130 positive; mean ± SEM) and 5.5 ± 1.2 trans-Golgi (dSyx-16 positive) per PR cell body scattered more or less evenly across the soma (Figures 2, A and E, and 3, A and F), with 45.6% ± 2.1 of cis-Golgi and 50.3% ± 1.9 of trans-Golgi in the basal half of the cell and the rest apical (Figures 2F and 3G). In contrast, when we overexpressed an Ena-GFP fusion, the number of distinguishable cisternae increased dramatically (to 8.6 ± 1.1 cis-Golgi, p = 2.1E-5; and 15.7 ± 0.9 trans-Golgi; p = 2.7E-4; Figures 2E and 3F), and the cisternae overwhelmingly relocalized to the most basal part of the cell soma, near the axon exit point (cis-Golgi, 97.5% ± 3.3 basal, p = 2.3E-4; and trans-Golgi, 79% ± 4.6 basal; p = 2.6E-5; Figures 2F and 3G). Both the expressed and the endogenous Ena relocalized in concert with the Golgi, coalescing at the most basal point of the cell soma (Figures 2B and 3D). We verified that the phenotype from ena overexpression was formally a genetic gain of function by showing that the severity of the phenotype was quantitatively reduced by heterozygosity for the endogenous ena locus (Figure S2, D and E).


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)

cis-Golgi complex is sensitive to the levels of Enabled protein. (A–C) Z-projections of confocal stacks of mature PR clusters labeled for Ena (green), cis-Golgi (GM130, red) and PR nuclei (Elav, blue). Individual PR cell bodies are traced (irregular white outlines). White boxes indicate regions shown enlarged to the right. Arrows point to Ena puncta; arrowheads point to GM130 puncta. Scale bar, 5 μm. (A) In wild type, Ena and cis-Golgi puncta are scattered throughout the cytoplasm of each PR cell body. (B) Ena overexpression relocates endogenous and expressed Ena to the basal end of PR cell body. Also note an increase in the number and accumulation of cis-Golgi cisternae in the vicinity of the accumulated Ena. Typically Ena accumulates to very high levels in one large basal punctum, whereas lower levels of Ena are detected in association with the other basal cisternae. (C) Ena loss of function (FP4-mito) increases the number of cis-Golgi cisternae throughout the PR cell body, whereas GM130 in control (AP4-mito) resembles WT (A). (D) Scheme used to quantify apicobasal distribution. Puncta were counted separately in the apical and basal halves of each photoreceptor. Data are expressed as puncta located in the basal halves of the cells as a percentage of the total. (E) Quantification of cis-Golgi fragmentation phenotypes. n is indicated on the bars; error bars represent SEM. Statistical significance by ANOVA (**p < 0.001). (F) cis-Golgi distribution in basal region of PR cell was quantified. n is indicated on the bars; error bars represent SEM. p values were calculated by ANOVA (**p < 0.001).
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Figure 2: cis-Golgi complex is sensitive to the levels of Enabled protein. (A–C) Z-projections of confocal stacks of mature PR clusters labeled for Ena (green), cis-Golgi (GM130, red) and PR nuclei (Elav, blue). Individual PR cell bodies are traced (irregular white outlines). White boxes indicate regions shown enlarged to the right. Arrows point to Ena puncta; arrowheads point to GM130 puncta. Scale bar, 5 μm. (A) In wild type, Ena and cis-Golgi puncta are scattered throughout the cytoplasm of each PR cell body. (B) Ena overexpression relocates endogenous and expressed Ena to the basal end of PR cell body. Also note an increase in the number and accumulation of cis-Golgi cisternae in the vicinity of the accumulated Ena. Typically Ena accumulates to very high levels in one large basal punctum, whereas lower levels of Ena are detected in association with the other basal cisternae. (C) Ena loss of function (FP4-mito) increases the number of cis-Golgi cisternae throughout the PR cell body, whereas GM130 in control (AP4-mito) resembles WT (A). (D) Scheme used to quantify apicobasal distribution. Puncta were counted separately in the apical and basal halves of each photoreceptor. Data are expressed as puncta located in the basal halves of the cells as a percentage of the total. (E) Quantification of cis-Golgi fragmentation phenotypes. n is indicated on the bars; error bars represent SEM. Statistical significance by ANOVA (**p < 0.001). (F) cis-Golgi distribution in basal region of PR cell was quantified. n is indicated on the bars; error bars represent SEM. p values were calculated by ANOVA (**p < 0.001).
Mentions: The number and subcellular distribution of Golgi cisternae were profoundly sensitive to the level of Ena protein (Figures 2, A– F, and 3, D and E). In WT we found 3.8 ± 1.0 cis-Golgi cisternae (GM130 positive; mean ± SEM) and 5.5 ± 1.2 trans-Golgi (dSyx-16 positive) per PR cell body scattered more or less evenly across the soma (Figures 2, A and E, and 3, A and F), with 45.6% ± 2.1 of cis-Golgi and 50.3% ± 1.9 of trans-Golgi in the basal half of the cell and the rest apical (Figures 2F and 3G). In contrast, when we overexpressed an Ena-GFP fusion, the number of distinguishable cisternae increased dramatically (to 8.6 ± 1.1 cis-Golgi, p = 2.1E-5; and 15.7 ± 0.9 trans-Golgi; p = 2.7E-4; Figures 2E and 3F), and the cisternae overwhelmingly relocalized to the most basal part of the cell soma, near the axon exit point (cis-Golgi, 97.5% ± 3.3 basal, p = 2.3E-4; and trans-Golgi, 79% ± 4.6 basal; p = 2.6E-5; Figures 2F and 3G). Both the expressed and the endogenous Ena relocalized in concert with the Golgi, coalescing at the most basal point of the cell soma (Figures 2B and 3D). We verified that the phenotype from ena overexpression was formally a genetic gain of function by showing that the severity of the phenotype was quantitatively reduced by heterozygosity for the endogenous ena locus (Figure S2, D and E).

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