alpha-Spectrin is required for ovarian follicle monolayer integrity in Drosophila melanogaster.
To understand the role of the spectrin-based membrane skeleton in generating epithelial polarity, we characterized the distribution of membrane skeletal components in Drosophila ovarian follicle cells and in somatic clones of mutant cells that lack alpha-spectrin. Immunolocalization data reveal that wild-type follicle cells contain two populations of spectrin heterodimers: a network of alphabeta heterodimers concentrated on the lateral plasma membrane and an alphabetaH population targeted to the apical surface. Induction of somatic clones lacking alpha-spectrin leads to follicle cell hyperplasia. Surprisingly, elimination of alpha-spectrin from follicle cells does not appear to prevent the assembly of conventional beta-spectrin and ankyrin at the lateral domain of the follicle cell plasma membrane. However, the alpha-subunit is essential for the correct localization of betaH-spectrin to the apical surface. As a consequence of disrupting the apical membrane skeleton a distinct sub population of follicle cells undergoes unregulated proliferation which leads to the loss of monolayer organization and disruption of the anterior-posterior axis of the oocyte. These results suggest that the spectrin-based membrane skeleton is required in a developmental pathway that controls follicle cell monolayer integrity and proliferation.
Lee
J K
JK
Howard Hughes Medical Institute, Department of Pharmacology, University of California, San Diego, La Jolla 92093-0683, USA.
Brandin
E
E
Branton
D
D
Goldstein
L S
LS
D000818:Animals; D017487:Ankyrins / Q000502:physiology; D002455:Cell Division; D002462:Cell Membrane / Q000502:physiology; D003433:Crosses, Genetic; D004331:Drosophila melanogaster; D004847:Epithelial Cells; D004848:Epithelium / Q000502:physiology; D005260:Female; D008297:Male; D009030:Mosaicism; D009865:Oocytes / Q000166:cytology / Q000502:physiology; D006080:Ovarian Follicle / Q000166:cytology* / Q000502:physiology*; D013049:Spectrin / Q000172:deficiency / Q000235:genetics / Q000502:physiology*
D017487:Ankyrins; D013049:Spectrin