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Filamin is required for ring canal assembly and actin organization during Drosophila oogenesis.

Li MG, Serr M, Edwards K, Ludmann S, Yamamoto D, Tilney LG, Field CM, Hays TS - J. Cell Biol. (1999)

Bottom Line: In consequence, actin-binding proteins are increasingly a focus of investigations into effectors of cell signaling and the coordination of cellular behaviors within developmental processes.Mutations in Drosophila filamin disrupt actin filament organization and compromise membrane integrity during oocyte development, resulting in female sterility.The genetic and molecular characterization of Drosophila filamin provides the first genetic model system for the analysis of filamin function and regulation during development.

View Article: PubMed Central - PubMed

Affiliation: Department of Genetics, Cell and Developmental Biology, University of Minnesota, St. Paul, Minnesota 55108, USA.

ABSTRACT
The remodeling of the actin cytoskeleton is essential for cell migration, cell division, and cell morphogenesis. Actin-binding proteins play a pivotal role in reorganizing the actin cytoskeleton in response to signals exchanged between cells. In consequence, actin-binding proteins are increasingly a focus of investigations into effectors of cell signaling and the coordination of cellular behaviors within developmental processes. One of the first actin-binding proteins identified was filamin, or actin-binding protein 280 (ABP280). Filamin is required for cell migration (Cunningham et al. 1992), and mutations in human alpha-filamin (FLN1; Fox et al. 1998) are responsible for impaired migration of cerebral neurons and give rise to periventricular heterotopia, a disorder that leads to epilepsy and vascular disorders, as well as embryonic lethality. We report the identification and characterization of a mutation in Drosophila filamin, the homologue of human alpha-filamin. During oogenesis, filamin is concentrated in the ring canal structures that fortify arrested cleavage furrows and establish cytoplasmic bridges between cells of the germline. The major structural features common to other filamins are conserved in Drosophila filamin. Mutations in Drosophila filamin disrupt actin filament organization and compromise membrane integrity during oocyte development, resulting in female sterility. The genetic and molecular characterization of Drosophila filamin provides the first genetic model system for the analysis of filamin function and regulation during development.

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Disruption of inner ring canal components in sko ovaries. Anti-anillin staining of wild-type (a) and sko (b) egg chambers shows anillin localization to the ring canal outer rim persists in the mutant (arrow). The distinct inner ring canal structures detected at stage 10 by anti-phosphotyrosine (c) and anti-hts (e) are deteriorated in the sko mutant egg chambers (d and f, respectively). Small aggregates recognized by these antibodies may represent remnants of ring canals. Bars: (a and b) 10 μm; (c–f) 50 μm.
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Figure 2: Disruption of inner ring canal components in sko ovaries. Anti-anillin staining of wild-type (a) and sko (b) egg chambers shows anillin localization to the ring canal outer rim persists in the mutant (arrow). The distinct inner ring canal structures detected at stage 10 by anti-phosphotyrosine (c) and anti-hts (e) are deteriorated in the sko mutant egg chambers (d and f, respectively). Small aggregates recognized by these antibodies may represent remnants of ring canals. Bars: (a and b) 10 μm; (c–f) 50 μm.

Mentions: Because actin organization is defective in sko mutant ring canals, we have examined other known ring canal components to further characterize the role of the sko gene product. Using an antibody against anillin, we compared patterns of anillin localization in wild-type and sko ovaries (Fig. 2, a and b). In wild-type egg chambers, anillin localization at ring canals is observed early in region 1 of the germarium and is easily detected through stage 6, with diminished levels still visible through stage 10. In sko ovaries, anillin is present in the stabilized cleavage furrow and persists at ring canals in a pattern similar to wild-type. Moreover, sko egg chambers contain the typical 16 cells, including 15 nurse cells and an oocyte. These results indicate that cytokinesis and initial ring canal formation are not defective. However, in contrast to wild-type, the anillin rings in sko mutant egg chambers appear reduced in size.


Filamin is required for ring canal assembly and actin organization during Drosophila oogenesis.

Li MG, Serr M, Edwards K, Ludmann S, Yamamoto D, Tilney LG, Field CM, Hays TS - J. Cell Biol. (1999)

Disruption of inner ring canal components in sko ovaries. Anti-anillin staining of wild-type (a) and sko (b) egg chambers shows anillin localization to the ring canal outer rim persists in the mutant (arrow). The distinct inner ring canal structures detected at stage 10 by anti-phosphotyrosine (c) and anti-hts (e) are deteriorated in the sko mutant egg chambers (d and f, respectively). Small aggregates recognized by these antibodies may represent remnants of ring canals. Bars: (a and b) 10 μm; (c–f) 50 μm.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2169474&req=5

Figure 2: Disruption of inner ring canal components in sko ovaries. Anti-anillin staining of wild-type (a) and sko (b) egg chambers shows anillin localization to the ring canal outer rim persists in the mutant (arrow). The distinct inner ring canal structures detected at stage 10 by anti-phosphotyrosine (c) and anti-hts (e) are deteriorated in the sko mutant egg chambers (d and f, respectively). Small aggregates recognized by these antibodies may represent remnants of ring canals. Bars: (a and b) 10 μm; (c–f) 50 μm.
Mentions: Because actin organization is defective in sko mutant ring canals, we have examined other known ring canal components to further characterize the role of the sko gene product. Using an antibody against anillin, we compared patterns of anillin localization in wild-type and sko ovaries (Fig. 2, a and b). In wild-type egg chambers, anillin localization at ring canals is observed early in region 1 of the germarium and is easily detected through stage 6, with diminished levels still visible through stage 10. In sko ovaries, anillin is present in the stabilized cleavage furrow and persists at ring canals in a pattern similar to wild-type. Moreover, sko egg chambers contain the typical 16 cells, including 15 nurse cells and an oocyte. These results indicate that cytokinesis and initial ring canal formation are not defective. However, in contrast to wild-type, the anillin rings in sko mutant egg chambers appear reduced in size.

Bottom Line: In consequence, actin-binding proteins are increasingly a focus of investigations into effectors of cell signaling and the coordination of cellular behaviors within developmental processes.Mutations in Drosophila filamin disrupt actin filament organization and compromise membrane integrity during oocyte development, resulting in female sterility.The genetic and molecular characterization of Drosophila filamin provides the first genetic model system for the analysis of filamin function and regulation during development.

View Article: PubMed Central - PubMed

Affiliation: Department of Genetics, Cell and Developmental Biology, University of Minnesota, St. Paul, Minnesota 55108, USA.

ABSTRACT
The remodeling of the actin cytoskeleton is essential for cell migration, cell division, and cell morphogenesis. Actin-binding proteins play a pivotal role in reorganizing the actin cytoskeleton in response to signals exchanged between cells. In consequence, actin-binding proteins are increasingly a focus of investigations into effectors of cell signaling and the coordination of cellular behaviors within developmental processes. One of the first actin-binding proteins identified was filamin, or actin-binding protein 280 (ABP280). Filamin is required for cell migration (Cunningham et al. 1992), and mutations in human alpha-filamin (FLN1; Fox et al. 1998) are responsible for impaired migration of cerebral neurons and give rise to periventricular heterotopia, a disorder that leads to epilepsy and vascular disorders, as well as embryonic lethality. We report the identification and characterization of a mutation in Drosophila filamin, the homologue of human alpha-filamin. During oogenesis, filamin is concentrated in the ring canal structures that fortify arrested cleavage furrows and establish cytoplasmic bridges between cells of the germline. The major structural features common to other filamins are conserved in Drosophila filamin. Mutations in Drosophila filamin disrupt actin filament organization and compromise membrane integrity during oocyte development, resulting in female sterility. The genetic and molecular characterization of Drosophila filamin provides the first genetic model system for the analysis of filamin function and regulation during development.

Show MeSH
Related in: MedlinePlus