Spectraplakin Shot Maintains Perinuclear Microtubule Organization in Drosophila Polyploid Cells

• Published in: Developmental cell Vol. 49; no. 5; pp. 731 - 747.e7
• Main Authors: Sun, Tianhui, Song, Yinlong, Dai, Jianli, Mao, Decai, Ma, Mengqi, Ni, Jian-Quan, Liang, Xin, Pastor-Pareja, José C.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 03.06.2019
• Subjects: Animals; Cell Nucleus - genetics; Cell Nucleus - metabolism; Cytokinesis; Drosophila melanogaster - physiology; Drosophila Proteins - genetics; Drosophila Proteins - metabolism; endocycle; endopolyploidy; Female; Katanin - genetics; Katanin - metabolism; LINC complex; Male; Microfilament Proteins - genetics; Microfilament Proteins - metabolism; Microtubule-Associated Proteins - genetics; Microtubule-Associated Proteins - metabolism; Microtubules - physiology; non-centrosomal MTOC; nuclear membrane; nuclear position; nuclear size; Polyploidy; Spindle Apparatus; nuclear position; endopolyploidy; endocycle; LINC complex; non-centrosomal MTOC; nuclear membrane; nuclear size
• ISSN: 1534-5807; 1878-1551
• DOI: 10.1016/j.devcel.2019.03.027

Polyploid cells endoreplicate their DNA through a modified cell cycle that skips mitosis as part of their differentiation programs. Upon cell-cycle exit and differentiation, non-centrosomal sites govern microtubule distribution in most cells. Little is known on how polyploid cells, differentiated but cycling, organize their microtubules. We show that microtubules in Drosophila adipocytes and other polyploid tissues form a dense perinuclear cortex responsible for nuclear size and position. Confirming a relation between this perinuclear cortex and the polyploid endocycle, polyploidization of normally diploid cells was sufficient for cortex formation. A critical component of the perinuclear microtubule organizer (pnMTOC) is Shot, absence of which caused collapse of the perinuclear network into a condensed organizer through kinesin-dependent microtubule sliding. Furthermore, this ectopic organizer was capable of directing partial assembly of a deeply disruptive cytokinesis furrow. In all, our study revealed the importance of perinuclear microtubule organization for stability of endocycling Drosophila cells. [Display omitted] •Perinuclear microtubule organization is characteristic of Drosophila polyploid cells•Absence of Shot causes pnMTOC collapse through kinesin-dependent microtubule sliding•The collapsed pnMTOC can direct partial assembly of a cytokinesis furrow•Patronin, Katanin, and LINC complex are also involved in pnMTOC formation Polyploid cells are differentiated but continue to replicate their DNA through a modified cell cycle. Sun et al. show that spectraplakin Shot maintains perinuclear microtubule organization in endocycling cells and prevents formation of a condensed microtubule organizer capable of triggering a cytokinesis program in these non-dividing cells.