The Drosophila mitotic spindle orientation machinery requires activation, not just localization. (11th January 2023)

• Record Type: Journal Article
• Authors: Neville, Kathryn E; Finegan, Tara M; Lowe, Nicholas; Bellomio, Philip M; Na, Daxiang; Bergstralh, Dan T
• Is Part Of: EMBO reports. Volume 24:Number 3(2023)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2023-01-11
• Subjects: discs large -- Drosophila -- pins -- spindle orientation; Molecular biology -- Periodicals; Molecular Biology -- Periodicals; Molecular biology; Periodicals; 572.8
• DOI: 10.15252/embr.202256074
• Languages: English
• ISSNs: 1469-221X

Abstract

Abstract: The orientation of the mitotic spindle at metaphase determines the placement of the daughter cells. Spindle orientation in animals typically relies on an evolutionarily conserved biological machine comprised of at least four proteins – called Pins, Gαi, Mud, and Dynein in flies – that exerts a pulling force on astral microtubules and reels the spindle into alignment. The canonical model for spindle orientation holds that the direction of pulling is determined by asymmetric placement of this machinery at the cell cortex. In most cell types, this placement is thought to be mediated by Pins, and a substantial body of literature is therefore devoted to identifying polarized cues that govern localized cortical enrichment of Pins. In this study we revisit the canonical model and find that it is incomplete. Spindle orientation in the Drosophila follicular epithelium and embryonic ectoderm requires not only Pins localization but also direct interaction between Pins and the multifunctional protein Discs large. This requirement can be over‐ridden by interaction with another Pins interacting protein, Inscuteable. Synopsis: In the Drosophila follicular epithelium and embryonic ectoderm, spindle orientation in the apical‐basal axis relies not only on the spatial localization of Pins but also on its interaction with a partner protein. Pins location may not always predict Mud localization or spindle orientation. Interaction between Pins and Discs large does not explain lateral localization of Pins during mitosis. The reorienting effect of ectopically expressed Inscuteable is Dlg‐independent. Abstract : In the Drosophila follicular epithelium and embryonic ectoderm, spindle orientation in the apical‐basal axis relies not only on the spatial localization of Pins but also on its interaction with a partner protein.