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Neville KE, Finegan TM, Lowe N, Bellomio PM, Na D, Bergstralh DT. The Drosophila mitotic spindle orientation machinery requires activation, not just localization. EMBO Rep 2023; 24:e56074. [PMID: 36629398 PMCID: PMC9986814 DOI: 10.15252/embr.202256074] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2022] [Revised: 12/12/2022] [Accepted: 12/22/2022] [Indexed: 01/12/2023] Open
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.
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Affiliation(s)
| | - Tara M Finegan
- Department of BiologyUniversity of RochesterRochesterNew YorkUSA
| | - Nicholas Lowe
- Department of BiologyUniversity of RochesterRochesterNew YorkUSA
| | | | - Daxiang Na
- Department of BiologyUniversity of RochesterRochesterNew YorkUSA
| | - Dan T Bergstralh
- Department of BiologyUniversity of RochesterRochesterNew YorkUSA
- Department of Physics & AstronomyUniversity of RochesterRochesterNew YorkUSA
- Department of Biomedical GeneticsUniversity of Rochester Medical CenterRochesterNew YorkUSA
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Wright BA, Kvansakul M, Schierwater B, Humbert PO. Cell polarity signalling at the birth of multicellularity: What can we learn from the first animals. Front Cell Dev Biol 2022; 10:1024489. [PMID: 36506100 PMCID: PMC9729800 DOI: 10.3389/fcell.2022.1024489] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2022] [Accepted: 10/31/2022] [Indexed: 11/25/2022] Open
Abstract
The innovation of multicellularity has driven the unparalleled evolution of animals (Metazoa). But how is a multicellular organism formed and how is its architecture maintained faithfully? The defining properties and rules required for the establishment of the architecture of multicellular organisms include the development of adhesive cell interactions, orientation of division axis, and the ability to reposition daughter cells over long distances. Central to all these properties is the ability to generate asymmetry (polarity), coordinated by a highly conserved set of proteins known as cell polarity regulators. The cell polarity complexes, Scribble, Par and Crumbs, are considered to be a metazoan innovation with apicobasal polarity and adherens junctions both believed to be present in all animals. A better understanding of the fundamental mechanisms regulating cell polarity and tissue architecture should provide key insights into the development and regeneration of all animals including humans. Here we review what is currently known about cell polarity and its control in the most basal metazoans, and how these first examples of multicellular life can inform us about the core mechanisms of tissue organisation and repair, and ultimately diseases of tissue organisation, such as cancer.
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Affiliation(s)
- Bree A. Wright
- Department of Biochemistry and Chemistry, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, VIC, Australia
| | - Marc Kvansakul
- Department of Biochemistry and Chemistry, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, VIC, Australia,Research Centre for Molecular Cancer Prevention, La Trobe University, Melbourne, VIC, Australia
| | - Bernd Schierwater
- Institute of Animal Ecology and Evolution, University of Veterinary Medicine Hannover, Foundation, Bünteweg, Hannover, Germany
| | - Patrick O. Humbert
- Department of Biochemistry and Chemistry, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, VIC, Australia,Research Centre for Molecular Cancer Prevention, La Trobe University, Melbourne, VIC, Australia,Department of Biochemistry and Pharmacology, University of Melbourne, Melbourne, VIC, Australia,Department of Clinical Pathology, University of Melbourne, Melbourne, VIC, Australia,*Correspondence: Patrick O. Humbert,
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Rathbun LI, Everett CA, Bergstralh DT. Emerging Cnidarian Models for the Study of Epithelial Polarity. Front Cell Dev Biol 2022; 10:854373. [PMID: 35433674 PMCID: PMC9012326 DOI: 10.3389/fcell.2022.854373] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Accepted: 03/01/2022] [Indexed: 11/13/2022] Open
Abstract
Epithelial tissues are vital to the function of most organs, providing critical functions such as secretion, protection, and absorption. Cells within an epithelial layer must coordinate to create functionally distinct apical, lateral, and basal surfaces in order to maintain proper organ function and organism viability. This is accomplished through the careful targeting of polarity factors to their respective locations within the cell, as well as the strategic placement of post-mitotic cells within the epithelium during tissue morphogenesis. The process of establishing and maintaining epithelial tissue integrity is conserved across many species, as important polarity factors and spindle orientation mechanisms can be found in many phyla. However, most of the information gathered about these processes and players has been investigated in bilaterian organisms such as C. elegans, Drosophila, and vertebrate species. This review discusses the advances made in the field of epithelial polarity establishment from more basal organisms, and the advantages to utilizing these simpler models. An increasing number of cnidarian model organisms have been sequenced in recent years, such as Hydra vulgaris and Nematostella vectensis. It is now feasible to investigate how polarity is established and maintained in basal organisms to gain an understanding of the most basal requirements for epithelial tissue morphogenesis.
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