Limits...
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.

Show MeSH

Related in: MedlinePlus

Abnormal cell morphology and disruption of actin organization in sko mutant egg chambers. Wild-type (left column) and sko (right column) egg chambers are compared and imaged by confocal microscopy. Anterior is to the left. (a and b) Stage 10 egg chambers stained with the fluorescent DNA dye propidium iodide. In the sko mutant egg chamber, polyploid nurse cell nuclei are seen in the oocyte compartment (arrow). (c–h) Egg chambers stained with rhodamine-labeled phalloidin to visualize actin filaments. (c and d) Defects of actin organization in ring canal structures (arrowhead) and in the subcortical network (arrow) are evident in stage 3 mutant egg chambers. (e and f) In stage 10 egg chambers, the distinct ring canals in wild-type are absent in the mutant. The radial arrays of filaments that extend between the nurse cell membranes and nuclei are disrupted in the mutant. An altered morphology of nurse cells is apparent. (g and h) High magnification images show the boundary region between the nurse cell and oocyte compartments of stage 10 egg chambers. Ring canals and the cytoplasmic actin network are clearly visualized in wild-type but are defective in sko. Bars: (a, b, e, and f) 50 μm; (c, d, g, and h) 10 μm.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC2169474&req=5

Figure 1: Abnormal cell morphology and disruption of actin organization in sko mutant egg chambers. Wild-type (left column) and sko (right column) egg chambers are compared and imaged by confocal microscopy. Anterior is to the left. (a and b) Stage 10 egg chambers stained with the fluorescent DNA dye propidium iodide. In the sko mutant egg chamber, polyploid nurse cell nuclei are seen in the oocyte compartment (arrow). (c–h) Egg chambers stained with rhodamine-labeled phalloidin to visualize actin filaments. (c and d) Defects of actin organization in ring canal structures (arrowhead) and in the subcortical network (arrow) are evident in stage 3 mutant egg chambers. (e and f) In stage 10 egg chambers, the distinct ring canals in wild-type are absent in the mutant. The radial arrays of filaments that extend between the nurse cell membranes and nuclei are disrupted in the mutant. An altered morphology of nurse cells is apparent. (g and h) High magnification images show the boundary region between the nurse cell and oocyte compartments of stage 10 egg chambers. Ring canals and the cytoplasmic actin network are clearly visualized in wild-type but are defective in sko. Bars: (a, b, e, and f) 50 μm; (c, d, g, and h) 10 μm.

Mentions: A female sterile mutation, shi kong (sko; “out of control” in Chinese), was generated by standard EMS mutagenesis. Homozygous sko mutant flies are viable, but females do not lay eggs. Mutant ovaries show an apparent arrest in oocyte growth at stage 10b and no mature egg chambers are observed. Further inspection of sko mutant egg chambers reveals several defects in cellular morphology and membrane integrity. In situ staining of DNA reveals the disruption of the normal spatial organization of germline nuclei in sko mutant egg chambers, and in late stages, entire nurse cells and/or nurse cell nuclei are sometimes seen to protrude into the posterior compartment normally occupied only by the growing oocyte (Fig. 1 b). Although follicle cells migrate to form a columnar epithelium surrounding the oocyte in sko mutants, their shape is frequently more elongated than in wild-type egg chambers. The subsequent centripetal movement of follicle cells along the anterior margin of the oocyte is also abnormal in many mutant egg chambers.


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)

Abnormal cell morphology and disruption of actin organization in sko mutant egg chambers. Wild-type (left column) and sko (right column) egg chambers are compared and imaged by confocal microscopy. Anterior is to the left. (a and b) Stage 10 egg chambers stained with the fluorescent DNA dye propidium iodide. In the sko mutant egg chamber, polyploid nurse cell nuclei are seen in the oocyte compartment (arrow). (c–h) Egg chambers stained with rhodamine-labeled phalloidin to visualize actin filaments. (c and d) Defects of actin organization in ring canal structures (arrowhead) and in the subcortical network (arrow) are evident in stage 3 mutant egg chambers. (e and f) In stage 10 egg chambers, the distinct ring canals in wild-type are absent in the mutant. The radial arrays of filaments that extend between the nurse cell membranes and nuclei are disrupted in the mutant. An altered morphology of nurse cells is apparent. (g and h) High magnification images show the boundary region between the nurse cell and oocyte compartments of stage 10 egg chambers. Ring canals and the cytoplasmic actin network are clearly visualized in wild-type but are defective in sko. Bars: (a, b, e, and f) 50 μm; (c, d, g, and h) 10 μm.
© Copyright Policy
Related In: Results  -  Collection

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

Figure 1: Abnormal cell morphology and disruption of actin organization in sko mutant egg chambers. Wild-type (left column) and sko (right column) egg chambers are compared and imaged by confocal microscopy. Anterior is to the left. (a and b) Stage 10 egg chambers stained with the fluorescent DNA dye propidium iodide. In the sko mutant egg chamber, polyploid nurse cell nuclei are seen in the oocyte compartment (arrow). (c–h) Egg chambers stained with rhodamine-labeled phalloidin to visualize actin filaments. (c and d) Defects of actin organization in ring canal structures (arrowhead) and in the subcortical network (arrow) are evident in stage 3 mutant egg chambers. (e and f) In stage 10 egg chambers, the distinct ring canals in wild-type are absent in the mutant. The radial arrays of filaments that extend between the nurse cell membranes and nuclei are disrupted in the mutant. An altered morphology of nurse cells is apparent. (g and h) High magnification images show the boundary region between the nurse cell and oocyte compartments of stage 10 egg chambers. Ring canals and the cytoplasmic actin network are clearly visualized in wild-type but are defective in sko. Bars: (a, b, e, and f) 50 μm; (c, d, g, and h) 10 μm.
Mentions: A female sterile mutation, shi kong (sko; “out of control” in Chinese), was generated by standard EMS mutagenesis. Homozygous sko mutant flies are viable, but females do not lay eggs. Mutant ovaries show an apparent arrest in oocyte growth at stage 10b and no mature egg chambers are observed. Further inspection of sko mutant egg chambers reveals several defects in cellular morphology and membrane integrity. In situ staining of DNA reveals the disruption of the normal spatial organization of germline nuclei in sko mutant egg chambers, and in late stages, entire nurse cells and/or nurse cell nuclei are sometimes seen to protrude into the posterior compartment normally occupied only by the growing oocyte (Fig. 1 b). Although follicle cells migrate to form a columnar epithelium surrounding the oocyte in sko mutants, their shape is frequently more elongated than in wild-type egg chambers. The subsequent centripetal movement of follicle cells along the anterior margin of the oocyte is also abnormal in many mutant egg chambers.

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