title: A multicomponent assembly pathway contributes to the formation of acentrosomal microtubule arrays in interphase Drosophila cells.
abstract: In animal cells, centrosomes nucleate microtubules that form polarized arrays to organize the cytoplasm. Drosophila presents an interesting paradox however, as centrosome-deficient mutant animals develop into viable adults. To understand this discrepancy, we analyzed behaviors of centrosomes and microtubules in Drosophila cells, in culture and in vivo, using a combination of live-cell imaging, electron microscopy, and RNAi. The canonical model of the cycle of centrosome function in animal cells states that centrosomes act as microtubule-organizing centers throughout the cell cycle. Unexpectedly, we found that many Drosophila cell-types display an altered cycle, in which functional centrosomes are only present during cell division. On mitotic exit, centrosomes disassemble producing interphase cells containing centrioles that lack microtubule-nucleating activity. Furthermore, steady-state interphase microtubule levels are not changed by codepleting both gamma-tubulins. However, gamma-tubulin RNAi delays microtubule regrowth after depolymerization, suggesting that it may function partially redundantly with another pathway. Therefore, we examined additional microtubule nucleating factors and found that Mini-spindles, CLIP-190, EB1, or dynein RNAi also delayed microtubule regrowth; surprisingly, this was not further prolonged when we codepleted gamma-tubulins. Taken together, these results modify our view of the cycle of centrosome function and reveal a multi-component acentrosomal microtubule assembly pathway to establish interphase microtubule arrays in Drosophila.
authors.affiliation: Department of Biology, Lineberger Comprehensive Cancer Center, and Carolina Center for Genome Sciences, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
authors.forename: Gregory C
authors.initials: GC
authors.lastname: Rogers
authors.forename: Nasser M
authors.initials: NM
authors.lastname: Rusan
authors.forename: Mark
authors.initials: M
authors.lastname: Peifer
authors.forename: Stephen L
authors.initials: SL
authors.lastname: Rogers
mesh_terms: D000818:Animals; D002502:Centrioles / Q000378:metabolism; D018385:Centrosome / Q000648:ultrastructure*; D004331:Drosophila melanogaster; D004398:Dyneins / Q000378:metabolism; D005786:Gene Expression Regulation; D049452:Green Fluorescent Proteins / Q000378:metabolism; D007399:Interphase; D046529:Microscopy, Electron, Transmission; D008856:Microscopy, Fluorescence; D008938:Mitosis; D008954:Models, Biological; D034622:RNA Interference; D008941:Spindle Apparatus; D014404:Tubulin / Q000378:metabolism
chemical_list: D014404:Tubulin; D049452:Green Fluorescent Proteins; D004398:Dyneins