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Tocan V, Hayase J, Kamakura S, Kohda A, Ohga S, Kohjima M, Sumimoto H. Hepatocyte polarity establishment and apical lumen formation are organized by Par3, Cdc42, and aPKC in conjunction with Lgl. J Biol Chem 2021; 297:101354. [PMID: 34717957 PMCID: PMC8637150 DOI: 10.1016/j.jbc.2021.101354] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Revised: 10/17/2021] [Accepted: 10/19/2021] [Indexed: 01/21/2023] Open
Abstract
Hepatocytes differ from columnar epithelial cells by their multipolar organization, which follows the initial formation of central lumen-sharing clusters of polarized cells as observed during liver development and regeneration. The molecular mechanism for hepatocyte polarity establishment, however, has been comparatively less studied than those for other epithelial cell types. Here, we show that the tight junction protein Par3 organizes hepatocyte polarization via cooperating with the small GTPase Cdc42 to target atypical protein kinase C (aPKC) to a cortical site near the center of cell-cell contacts. In 3D Matrigel culture of human hepatocytic HepG2 cells, which mimics a process of liver development and regeneration, depletion of Par3, Cdc42, or aPKC results in an impaired establishment of apicobasolateral polarity and a loss of subsequent apical lumen formation. The aPKC activity is also required for bile canalicular (apical) elongation in mouse primary hepatocytes. The lateral membrane-associated proteins Lgl1 and Lgl2, major substrates of aPKC, seem to be dispensable for hepatocyte polarity establishment because Lgl-depleted HepG2 cells are able to form a single apical lumen in 3D culture. On the other hand, Lgl depletion leads to lateral invasion of aPKC, and overexpression of Lgl1 or Lgl2 prevents apical lumen formation, indicating that they maintain proper lateral integrity. Thus, hepatocyte polarity establishment and apical lumen formation are organized by Par3, Cdc42, and aPKC; Par3 cooperates with Cdc42 to recruit aPKC, which plays a crucial role in apical membrane development and regulation of the lateral maintainer Lgl.
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Affiliation(s)
- Vlad Tocan
- Department of Biochemistry, Kyushu University Graduate School of Medical Sciences, Fukuoka, Japan
| | - Junya Hayase
- Department of Biochemistry, Kyushu University Graduate School of Medical Sciences, Fukuoka, Japan
| | - Sachiko Kamakura
- Department of Biochemistry, Kyushu University Graduate School of Medical Sciences, Fukuoka, Japan
| | - Akira Kohda
- Department of Biochemistry, Kyushu University Graduate School of Medical Sciences, Fukuoka, Japan
| | - Shouichi Ohga
- Department of Pediatrics, Kyushu University Graduate School of Medical Sciences, Fukuoka, Japan
| | - Motoyuki Kohjima
- Department of Biochemistry, Kyushu University Graduate School of Medical Sciences, Fukuoka, Japan; Department of Medicine and Regulatory Science, Kyushu University Graduate School of Medical Sciences, Fukuoka, Japan
| | - Hideki Sumimoto
- Department of Biochemistry, Kyushu University Graduate School of Medical Sciences, Fukuoka, Japan.
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Lu J, Dong W, Tao Y, Hong Y. Electrostatic plasma membrane targeting contributes to Dlg function in cell polarity and tumorigenesis. Development 2021; 148:dev196956. [PMID: 33688074 PMCID: PMC8034875 DOI: 10.1242/dev.196956] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Accepted: 02/26/2021] [Indexed: 12/31/2022]
Abstract
Discs large (Dlg) is an essential polarity protein and a tumor suppressor originally characterized in Drosophila but also well conserved in vertebrates. Like the majority of polarity proteins, plasma membrane (PM)/cortical localization of Dlg is required for its function in polarity and tumorigenesis, but the exact mechanisms targeting Dlg to the PM remain to be fully elucidated. Here, we show that, similar to recently discovered polybasic polarity proteins such as Lgl and aPKC, Dlg also contains a positively charged polybasic domain that electrostatically binds the PM phosphoinositides PI4P and PI(4,5)P2 Electrostatic targeting by the polybasic domain contributes significantly to the PM localization of Dlg in follicular and early embryonic epithelial cells, and is crucial for Dlg to regulate both polarity and tumorigenesis. The electrostatic PM targeting of Dlg is controlled by a potential phosphorylation-dependent allosteric regulation of its polybasic domain, and is specifically enhanced by the interactions between Dlg and another basolateral polarity protein and tumor suppressor, Scrib. Our studies highlight an increasingly significant role of electrostatic PM targeting of polarity proteins in regulating cell polarity.
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Affiliation(s)
- Juan Lu
- Department of Cell Biology, University of Pittsburgh Medical School, Pittsburgh, PA 15261, USA
| | - Wei Dong
- Department of Cell Biology, University of Pittsburgh Medical School, Pittsburgh, PA 15261, USA
| | - Yan Tao
- Jiangsu University, Zhengjiang, Jiangsu 212013, People's Republic of China
| | - Yang Hong
- Department of Cell Biology, University of Pittsburgh Medical School, Pittsburgh, PA 15261, USA
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Ventura G, Moreira S, Barros-Carvalho A, Osswald M, Morais-de-Sá E. Lgl cortical dynamics are independent of binding to the Scrib-Dlg complex but require Dlg-dependent restriction of aPKC. Development 2020; 147:dev.186593. [PMID: 32665243 DOI: 10.1242/dev.186593] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Accepted: 07/02/2020] [Indexed: 01/06/2023]
Abstract
Apical-basal polarity underpins the formation of epithelial barriers that are crucial for metazoan physiology. Although apical-basal polarity is long known to require the basolateral determinants Lethal Giant Larvae (Lgl), Discs Large (Dlg) and Scribble (Scrib), mechanistic understanding of their function is limited. Lgl plays a role as an aPKC inhibitor, but it remains unclear whether Lgl also forms complexes with Dlg or Scrib. Using fluorescence recovery after photobleaching, we show that Lgl does not form immobile complexes at the lateral domain of Drosophila follicle cells. Optogenetic depletion of plasma membrane PIP2 or dlg mutants accelerate Lgl cortical dynamics. However, Dlg and Scrib are required only for Lgl localization and dynamic behavior in the presence of aPKC function. Furthermore, light-induced oligomerization of basolateral proteins indicates that Lgl is not part of the Scrib-Dlg complex in the follicular epithelium. Thus, Scrib and Dlg are necessary to repress aPKC activity in the lateral domain but do not provide cortical binding sites for Lgl. Our work therefore highlights that Lgl does not act in a complex but in parallel with Scrib-Dlg to antagonize apical determinants.
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Affiliation(s)
- Guilherme Ventura
- i3S (Instituto de Investigação e Inovação em Saúde, Universidade do Porto) and IBMC (Instituto de Biologia Molecular e Celular), Rua Alfredo Allen, 208, 4200-135 Porto, Portugal
| | - Sofia Moreira
- i3S (Instituto de Investigação e Inovação em Saúde, Universidade do Porto) and IBMC (Instituto de Biologia Molecular e Celular), Rua Alfredo Allen, 208, 4200-135 Porto, Portugal
| | - André Barros-Carvalho
- i3S (Instituto de Investigação e Inovação em Saúde, Universidade do Porto) and IBMC (Instituto de Biologia Molecular e Celular), Rua Alfredo Allen, 208, 4200-135 Porto, Portugal
| | - Mariana Osswald
- i3S (Instituto de Investigação e Inovação em Saúde, Universidade do Porto) and IBMC (Instituto de Biologia Molecular e Celular), Rua Alfredo Allen, 208, 4200-135 Porto, Portugal
| | - Eurico Morais-de-Sá
- i3S (Instituto de Investigação e Inovação em Saúde, Universidade do Porto) and IBMC (Instituto de Biologia Molecular e Celular), Rua Alfredo Allen, 208, 4200-135 Porto, Portugal
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Moreira S, Osswald M, Ventura G, Gonçalves M, Sunkel CE, Morais-de-Sá E. PP1-Mediated Dephosphorylation of Lgl Controls Apical-basal Polarity. Cell Rep 2020; 26:293-301.e7. [PMID: 30625311 DOI: 10.1016/j.celrep.2018.12.060] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Revised: 11/23/2018] [Accepted: 12/13/2018] [Indexed: 12/17/2022] Open
Abstract
Apical-basal polarity is a common trait that underlies epithelial function. Although the asymmetric distribution of cortical polarity proteins works in a functioning equilibrium, it also retains plasticity to accommodate cell division, during which the basolateral determinant Lgl is released from the cortex. Here, we investigated how Lgl restores its cortical localization to maintain the integrity of dividing epithelia. We show that cytoplasmic Lgl is reloaded to the cortex at mitotic exit in Drosophila epithelia. Lgl cortical localization depends on protein phosphatase 1, which dephosphorylates Lgl on the serines phosphorylated by aPKC and Aurora A kinases through a mechanism that relies on the regulatory subunit Sds22 and a PP1-interacting RVxF motif of Lgl. This mechanism maintains epithelial polarity and is of particular importance at mitotic exit to couple Lgl cortical reloading with the polarization of the apical domain. Hence, PP1-mediated dephosphorylation of Lgl preserves the apical-basal organization of proliferative epithelia.
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Affiliation(s)
- Sofia Moreira
- Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal; Instituto de Investigação e Inovação em Saúde (i3S), Universidade do Porto, Porto, Portugal
| | - Mariana Osswald
- Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal; Instituto de Investigação e Inovação em Saúde (i3S), Universidade do Porto, Porto, Portugal
| | - Guilherme Ventura
- Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal; Instituto de Investigação e Inovação em Saúde (i3S), Universidade do Porto, Porto, Portugal
| | - Margarida Gonçalves
- Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal; Instituto de Investigação e Inovação em Saúde (i3S), Universidade do Porto, Porto, Portugal
| | - Claudio E Sunkel
- Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal; Instituto de Investigação e Inovação em Saúde (i3S), Universidade do Porto, Porto, Portugal
| | - Eurico Morais-de-Sá
- Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal; Instituto de Investigação e Inovação em Saúde (i3S), Universidade do Porto, Porto, Portugal.
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Magre I, Fandade V, Damle I, Banerjee P, Yadav SK, Sonawane M, Joseph J. Nup358 regulates microridge length by controlling SUMOylation-dependent activity of aPKC in zebrafish epidermis. J Cell Sci 2019; 132:jcs.224501. [PMID: 31164446 DOI: 10.1242/jcs.224501] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2018] [Accepted: 05/20/2019] [Indexed: 01/05/2023] Open
Abstract
The Par polarity complex, consisting of Par3, Par6 and atypical protein kinase C (aPKC), plays a crucial role in the establishment and maintenance of cell polarity. Although activation of aPKC is critical for polarity, how this is achieved is unclear. The developing zebrafish epidermis, along with its apical actin-based projections, called microridges, offers a genetically tractable system for unraveling the mechanisms of the cell polarity control. The zebrafish aPKC regulates elongation of microridges by controlling levels of apical Lgl, which acts as a pro-elongation factor. Here, we show that the nucleoporin Nup358 (also known as RanBP2) - a component of the nuclear pore complex and a part of cytoplasmic annulate lamellae (AL) - SUMOylates zebrafish aPKC. Nup358-mediated SUMOylation controls aPKC activity to regulate Lgl-dependent microridge elongation. Our data further suggest that cytoplasmic AL structures are the possible site for Nup358-mediated aPKC SUMOylation. We have unraveled a hitherto unappreciated contribution of Nup358-mediated aPKC SUMOylation in cell polarity regulation.This article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
- Indrasen Magre
- National Center for Cell Science, S.P. Pune University Campus, Pune 411 007, India
| | - Vikas Fandade
- National Center for Cell Science, S.P. Pune University Campus, Pune 411 007, India
| | - Indraneel Damle
- Department of Biological Sciences, Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400 005, India
| | - Poulomi Banerjee
- National Center for Cell Science, S.P. Pune University Campus, Pune 411 007, India
| | - Santosh Kumar Yadav
- National Center for Cell Science, S.P. Pune University Campus, Pune 411 007, India
| | - Mahendra Sonawane
- Department of Biological Sciences, Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400 005, India
| | - Jomon Joseph
- National Center for Cell Science, S.P. Pune University Campus, Pune 411 007, India
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Abstract
In the companion paper by Ufimtsev and Levitt [Ufimtsev IS, Levitt M (2019) Proc Natl Acad Sci USA, 10.1073/pnas.1821512116], we presented a method for unsupervised solution of protein crystal structures and demonstrated its utility by solving several test cases of known structure in the 2.9- to 3.45-Å resolution range. Here we apply this method to solve the crystal structure of a 966-amino acid construct of human lethal giant larvae protein (Lgl2) that resisted years of structure determination efforts, at 3.2-Å resolution. The structure was determined starting with a molecular replacement (MR) model identified by unsupervised refinement of a pool of 50 candidate MR models. This initial model had 2.8-Å RMSD from the solution. The solved structure was validated by comparison with a model subsequently derived from an alternative crystal form diffracting to higher resolution. This model could phase an anomalous difference Fourier map from an Hg derivative, and a single-wavelength anomalous dispersion phased density map made from these sites aligned with the refined structure.
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Affiliation(s)
- Ivan S Ufimtsev
- Department of Structural Biology, Stanford University School of Medicine, Stanford, CA 94305
| | - Lior Almagor
- Department of Structural Biology, Stanford University School of Medicine, Stanford, CA 94305
- Department of Molecular & Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305
| | - William I Weis
- Department of Structural Biology, Stanford University School of Medicine, Stanford, CA 94305;
- Department of Molecular & Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305
| | - Michael Levitt
- Department of Structural Biology, Stanford University School of Medicine, Stanford, CA 94305;
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Almagor L, Ufimtsev IS, Ayer A, Li J, Weis WI. Structural insights into the aPKC regulatory switch mechanism of the human cell polarity protein lethal giant larvae 2. Proc Natl Acad Sci U S A 2019; 116:10804-12. [PMID: 31088962 DOI: 10.1073/pnas.1821514116] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Metazoan cell polarity is controlled by a set of highly conserved proteins. Lethal giant larvae (Lgl) functions in apical-basal polarity through phosphorylation-dependent interactions with several other proteins as well as the plasma membrane. Phosphorylation of Lgl by atypical protein kinase C (aPKC), a component of the partitioning-defective (Par) complex in epithelial cells, excludes Lgl from the apical membrane, a crucial step in the establishment of epithelial cell polarity. We present the crystal structures of human Lgl2 in both its unphosphorylated and aPKC-phosphorylated states. Lgl2 adopts a double β-propeller structure that is unchanged by aPKC phosphorylation of an unstructured loop in its second β-propeller, ruling out models of phosphorylation-dependent conformational change. We demonstrate that phosphorylation controls the direct binding of purified Lgl2 to negative phospholipids in vitro. We also show that a coil-helix transition of this region that is promoted by phosphatidylinositol 4,5-bisphosphate (PIP2) is also phosphorylation-dependent, implying a highly effective phosphorylative switch for membrane association.
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Milgrom-Hoffman M, Humbert PO. Regulation of cellular and PCP signalling by the Scribble polarity module. Semin Cell Dev Biol 2017; 81:33-45. [PMID: 29154823 DOI: 10.1016/j.semcdb.2017.11.021] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2017] [Revised: 11/11/2017] [Accepted: 11/13/2017] [Indexed: 10/18/2022]
Abstract
Since the first identification of the Scribble polarity module proteins as a new class of tumour suppressors that regulate both cell polarity and proliferation, an increasing amount of evidence has uncovered a broader role for Scribble, Dlg and Lgl in the control of fundamental cellular functions and their signalling pathways. Here, we review these findings as well as discuss more specifically the role of the Scribble module in PCP signalling.
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Affiliation(s)
- Michal Milgrom-Hoffman
- Department of Biochemistry & Genetics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, Victoria 3086, Australia
| | - Patrick O Humbert
- Department of Biochemistry & Genetics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, Victoria 3086, Australia; Department of Biochemistry & Molecular Biology, University of Melbourne, Melbourne, Victoria 3010, Australia; Department of Pathology, University of Melbourne, Melbourne, Victoria 3010, Australia.
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Abstract
Intracellular asymmetries, often termed cell polarity, determine how cells organize and divide to ultimately control cell fate and shape animal tissues. The tumor suppressor Lethal giant larvae (Lgl) functions at the core of the evolutionarily conserved cell polarity machinery that controls apico-basal polarization. This function relies on its restricted basolateral localization via phosphorylation by aPKC. Here, we summarize the spatial and temporal control of Lgl during the cell cycle, highlighting two ideas that emerged from our recent findings: 1) Aurora A directly phosphorylates Lgl during symmetric division to couple reorganization of epithelial polarity with the cell cycle; 2) Phosphorylation of Lgl within three conserved serines controls its localization and function in a site-specific manner. Considering the importance of phosphorylation to regulate the concentration of Lgl at the plasma membrane, we will further discuss how it may work as an on-off switch for the interaction with cortical binding partners, with implications on epithelial polarization and spindle orientation.
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Affiliation(s)
- Sofia Moreira
- a IBMC, Instituto de Biologia Molecular e Celular, Universidade do Porto , Porto , Portugal.,b I3S, Instituto de Investigação e Inovação em Saúde, Universidade do Porto , Porto , Portugal
| | - Eurico Morais-de-Sá
- a IBMC, Instituto de Biologia Molecular e Celular, Universidade do Porto , Porto , Portugal.,b I3S, Instituto de Investigação e Inovação em Saúde, Universidade do Porto , Porto , Portugal
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