A nuclear lamin is required for cytoplasmic organization and egg polarity in Drosophila.
Nuclear lamins are intermediate filaments that compose the nuclear lamina--the filamentous meshwork underlying the inner nuclear membrane--and are required for nuclear assembly, organization and maintenance. Here we present evidence that a nuclear lamin is also required for cytoplasmic organization in two highly polarized cell types. Zygotic loss-of-function mutations in the Drosophila gene encoding the principal lamin (Dm(0)) disrupt the directed outgrowth of cytoplasmic extensions from terminal cells of the tracheal system. Germline mutant clones disrupt dorsal-ventral polarity of the oocyte. In mutant oocytes, transcripts of the dorsal determinant Gurken, a transforming growth factor-alpha homologue, fail to localize properly around the anterodorsal surface of the oocyte nucleus; their ventral spread results in dorsalized eggs that resemble those of the classical dorsalizing mutations squid and fs(1)K10. The requirement of a nuclear lamin for cytoplasmic as well as nuclear organization has important implications for both the cellular functions of lamins and the pathogenesis of human diseases caused by lamin mutations.
Guillemin
K
K
Department of Biochemistry and Howard Hughes Medical Institute, Stanford University School of Medicine, Stanford, CA 94305-5307, USA.
Williams
T
T
Krasnow
M A
MA
D000818:Animals; D001483:Base Sequence; D002455:Cell Division; D002467:Cell Nucleus / Q000502:physiology* / Q000648:ultrastructure; D016764:Cell Polarity; D003593:Cytoplasm / Q000502:physiology / Q000648:ultrastructure; D004330:Drosophila / Q000196:embryology / Q000235:genetics* / Q000502:physiology*; D029721:Drosophila Proteins; D005260:Female; D005786:Gene Expression Regulation; D018095:Germ-Line Mutation; D006801:Humans; D007301:Insect Hormones / Q000235:genetics; D019476:Insect Proteins / Q000235:genetics; D034882:Lamins; D008969:Molecular Sequence Data; D009024:Morphogenesis / Q000502:physiology*; D009687:Nuclear Proteins / Q000235:genetics* / Q000378:metabolism; D009865:Oocytes / Q000166:cytology* / Q000502:physiology*; D016601:RNA-Binding Proteins / Q000235:genetics; D014158:Transcription, Genetic; D016211:Transforming Growth Factor alpha; D015291:Transforming Growth Factors / Q000235:genetics; D015053:Zygote / Q000166:cytology / Q000502:physiology
D029721:Drosophila Proteins; D007301:Insect Hormones; D019476:Insect Proteins; D034882:Lamins; D009687:Nuclear Proteins; D016601:RNA-Binding Proteins; D016211:Transforming Growth Factor alpha; C083730:grk protein, Drosophila; C081480:sqd protein, Drosophila; D015291:Transforming Growth Factors