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Hulsey-Vincent HJ, Cameron EA, Dahlberg CL, Galati DF. Spectral scanning and fluorescence lifetime imaging microscopy (FLIM) enable separation and characterization of C. elegans autofluorescence in the cuticle and gut. Biol Open 2024; 13:bio060613. [PMID: 39714513 PMCID: PMC11708769 DOI: 10.1242/bio.060613] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2024] [Accepted: 11/19/2024] [Indexed: 12/24/2024] Open
Abstract
Caenorhabditis elegans gut and cuticle produce a disruptive amount of autofluorescence during imaging. Although C. elegans autofluorescence has been characterized, it has not been characterized at high resolution using both spectral and fluorescence lifetime-based approaches. We performed high resolution spectral scans of whole, living animals to characterize autofluorescence of adult C. elegans. By scanning animals at 405 nm, 473 nm, 561 nm, and 647 nm excitations, we produced spectral profiles that confirm the brightest autofluorescence has a clear spectral overlap with the emission of green fluorescent protein (GFP). We then used fluorescence lifetime imaging microscopy (FLIM) to further characterize autofluorescence in the cuticle and the gut. Using FLIM, we were able to isolate and quantify dim GFP signal within the sensory cilia of a single pair of neurons that is often obscured by cuticle autofluorescence. In the gut, we found distinct spectral populations of autofluorescence that could be excited by 405 nm and 473 nm lasers. Further, we found lifetime differences between subregions of this autofluorescence when stimulated at 473 nm. Our results suggest that FLIM can be used to differentiate biochemically unique populations of gut autofluorescence without labeling. Further studies involving C. elegans may benefit from combining high resolution spectral and lifetime imaging to isolate fluorescent protein signal that is mixed with background autofluorescence and to perform useful characterization of subcellular structures in a label-free manner.
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Rodrigues NTL, Bland T, Ng K, Hirani N, Goehring NW. Quantitative perturbation-phenotype maps reveal nonlinear responses underlying robustness of PAR-dependent asymmetric cell division. PLoS Biol 2024; 22:e3002437. [PMID: 39652540 PMCID: PMC11627365 DOI: 10.1371/journal.pbio.3002437] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2023] [Accepted: 10/30/2024] [Indexed: 12/12/2024] Open
Abstract
A key challenge in the development of an organism is to maintain robust phenotypic outcomes in the face of perturbation. Yet, it is often unclear how such robust outcomes are encoded by developmental networks. Here, we use the Caenorhabditis elegans zygote as a model to understand sources of developmental robustness during PAR polarity-dependent asymmetric cell division. By quantitatively linking alterations in protein dosage to phenotype in individual embryos, we show that spatial information in the zygote is read out in a highly nonlinear fashion and, as a result, phenotypes are highly canalized against substantial variation in input signals. Our data point towards robustness of the conserved PAR polarity network that renders polarity axis specification resistant to variations in both the strength of upstream symmetry-breaking cues and PAR protein dosage. Analogously, downstream pathways involved in cell size and fate asymmetry are robust to dosage-dependent changes in the local concentrations of PAR proteins, implying nontrivial complexity in translating PAR concentration profiles into pathway outputs. We propose that these nonlinear signal-response dynamics between symmetry-breaking, PAR polarity, and asymmetric division modules effectively insulate each individual module from variation arising in others. This decoupling helps maintain the embryo along the correct developmental trajectory, thereby ensuring that asymmetric division is robust to perturbation. Such modular organization of developmental networks is likely to be a general mechanism to achieve robust developmental outcomes.
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Affiliation(s)
| | - Tom Bland
- The Francis Crick Institute, London, United Kingdom
- Institute for the Physics of Living Systems, University College London, London, United Kingdom
| | - KangBo Ng
- The Francis Crick Institute, London, United Kingdom
- Institute for the Physics of Living Systems, University College London, London, United Kingdom
| | - Nisha Hirani
- The Francis Crick Institute, London, United Kingdom
| | - Nathan W. Goehring
- The Francis Crick Institute, London, United Kingdom
- Institute for the Physics of Living Systems, University College London, London, United Kingdom
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Bland T, Hirani N, Briggs DC, Rossetto R, Ng K, Taylor IA, McDonald NQ, Zwicker D, Goehring NW. Optimized PAR-2 RING dimerization mediates cooperative and selective membrane binding for robust cell polarity. EMBO J 2024; 43:3214-3239. [PMID: 38907033 PMCID: PMC11294563 DOI: 10.1038/s44318-024-00123-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2023] [Revised: 05/01/2024] [Accepted: 05/08/2024] [Indexed: 06/23/2024] Open
Abstract
Cell polarity networks are defined by quantitative features of their constituent feedback circuits, which must be tuned to enable robust and stable polarization, while also ensuring that networks remain responsive to dynamically changing cellular states and/or spatial cues during development. Using the PAR polarity network as a model, we demonstrate that these features are enabled by the dimerization of the polarity protein PAR-2 via its N-terminal RING domain. Combining theory and experiment, we show that dimer affinity is optimized to achieve dynamic, selective, and cooperative binding of PAR-2 to the plasma membrane during polarization. Reducing dimerization compromises positive feedback and robustness of polarization. Conversely, enhanced dimerization renders the network less responsive due to kinetic trapping of PAR-2 on internal membranes and reduced sensitivity of PAR-2 to the anterior polarity kinase, aPKC/PKC-3. Thus, our data reveal a key role for a dynamically oligomeric RING domain in optimizing interaction affinities to support a robust and responsive cell polarity network, and highlight how optimization of oligomerization kinetics can serve as a strategy for dynamic and cooperative intracellular targeting.
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Affiliation(s)
- Tom Bland
- Francis Crick Institute, London, NW1 1AT, UK
- Institute for the Physics of Living Systems, University College London, London, UK
| | | | | | - Riccardo Rossetto
- Max Planck Institute for Dynamics and Self-Organization, Göttingen, Germany
| | - KangBo Ng
- Francis Crick Institute, London, NW1 1AT, UK
- Institute for the Physics of Living Systems, University College London, London, UK
| | | | - Neil Q McDonald
- Francis Crick Institute, London, NW1 1AT, UK
- Institute of Structural and Molecular Biology, Department of Biological Sciences, Birkbeck College, London, WC1E 7HX, UK
| | - David Zwicker
- Max Planck Institute for Dynamics and Self-Organization, Göttingen, Germany
| | - Nathan W Goehring
- Francis Crick Institute, London, NW1 1AT, UK.
- Institute for the Physics of Living Systems, University College London, London, UK.
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Barbieri S, Gotta M. Order from chaos: cellular asymmetries explained with modelling. Trends Cell Biol 2024; 34:122-135. [PMID: 37574346 DOI: 10.1016/j.tcb.2023.06.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2023] [Revised: 06/26/2023] [Accepted: 06/28/2023] [Indexed: 08/15/2023]
Abstract
Molecules inside cells are subject to physical forces and undergo biochemical interactions, continuously changing their physical properties and dynamics. Despite this, cells achieve highly ordered molecular patterns that are crucial to regulate various cellular functions and to specify cell fate. In the Caenorhabditis elegans one-cell embryo, protein asymmetries are established in the narrow time window of a cell division. What are the mechanisms that allow molecules to establish asymmetries, defying the randomness imposed by Brownian motion? Mathematical and computational models have paved the way to the understanding of protein dynamics up to the 'single-molecule level' when resolution represents an issue for precise experimental measurements. Here we review the models that interpret cortical and cytoplasmic asymmetries in the one-cell C. elegans embryo.
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Affiliation(s)
- Sofia Barbieri
- Department of Cell Physiology and Metabolism, Faculty of Medicine, University of Geneva, Geneva 1211, Switzerland.
| | - Monica Gotta
- Department of Cell Physiology and Metabolism, Faculty of Medicine, University of Geneva, Geneva 1211, Switzerland
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Ng K, Hirani N, Bland T, Borrego-Pinto J, Wagner S, Kreysing M, Goehring NW. Cleavage furrow-directed cortical flows bias PAR polarization pathways to link cell polarity to cell division. Curr Biol 2023; 33:4298-4311.e6. [PMID: 37729912 DOI: 10.1016/j.cub.2023.08.076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2023] [Revised: 07/13/2023] [Accepted: 08/24/2023] [Indexed: 09/22/2023]
Abstract
During development, the conserved PAR polarity network is continuously redeployed, requiring that it adapt to changing cellular contexts and environmental cues. In the early C. elegans embryo, polarity shifts from being a cell-autonomous process in the zygote to one that must be coordinated between neighbors as the embryo becomes multicellular. Here, we sought to explore how the PAR network adapts to this shift in the highly tractable C. elegans germline P lineage. We find that although P lineage blastomeres exhibit a distinct pattern of polarity emergence compared with the zygote, the underlying mechanochemical processes that drive polarity are largely conserved. However, changes in the symmetry-breaking cues of P lineage blastomeres ensure coordination of their polarity axis with neighboring cells. Specifically, we show that furrow-directed cortical flows associated with cytokinesis of the zygote induce symmetry breaking in the germline blastomere P1 by transporting PAR-3 into the nascent cell contact. This pool of PAR-3 then biases downstream PAR polarization pathways to establish the polarity axis of P1 with respect to the position of its anterior sister, AB. Thus, our data suggest that cytokinesis itself induces symmetry breaking through the advection of polarity proteins by furrow-directed flows. By directly linking cell polarity to cell division, furrow-directed cortical flows could be a general mechanism to ensure proper organization of cell polarity within actively dividing systems.
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Affiliation(s)
- KangBo Ng
- The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK; Institute for the Physics of Living Systems, University College London, London WC1E 6BT, UK
| | - Nisha Hirani
- The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Tom Bland
- The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK; Institute for the Physics of Living Systems, University College London, London WC1E 6BT, UK
| | | | - Susan Wagner
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstraße 108, 01307 Dresden, Germany; Institute of Biological and Chemical Systems, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - Moritz Kreysing
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstraße 108, 01307 Dresden, Germany; Institute of Biological and Chemical Systems, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - Nathan W Goehring
- The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK; Institute for the Physics of Living Systems, University College London, London WC1E 6BT, UK.
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Illukkumbura R, Hirani N, Borrego-Pinto J, Bland T, Ng K, Hubatsch L, McQuade J, Endres RG, Goehring NW. Design principles for selective polarization of PAR proteins by cortical flows. J Cell Biol 2023; 222:e202209111. [PMID: 37265444 PMCID: PMC10238861 DOI: 10.1083/jcb.202209111] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Revised: 03/08/2023] [Accepted: 05/09/2023] [Indexed: 06/03/2023] Open
Abstract
Clustering of membrane-associated molecules is thought to promote interactions with the actomyosin cortex, enabling size-dependent transport by actin flows. Consistent with this model, in the Caenorhabditis elegans zygote, efficient anterior segregation of the polarity protein PAR-3 requires oligomerization. However, through direct assessment of local coupling between motion of PAR proteins and the underlying cortex, we find no links between PAR-3 oligomer size and the degree of coupling. Indeed, both anterior and posterior PAR proteins experience similar advection velocities, at least over short distances. Consequently, differential cortex engagement cannot account for selectivity of PAR protein segregation by cortical flows. Combining experiment and theory, we demonstrate that a key determinant of differential segregation of PAR proteins by cortical flow is the stability of membrane association, which is enhanced by clustering and enables transport across cellular length scales. Thus, modulation of membrane binding dynamics allows cells to achieve selective transport by cortical flows despite widespread coupling between membrane-associated molecules and the cell cortex.
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Affiliation(s)
- Rukshala Illukkumbura
- The Francis Crick Institute, London, UK
- Institute for the Physics of Living Systems, University College London, London, UK
| | | | | | - Tom Bland
- The Francis Crick Institute, London, UK
- Institute for the Physics of Living Systems, University College London, London, UK
| | - KangBo Ng
- The Francis Crick Institute, London, UK
- Institute for the Physics of Living Systems, University College London, London, UK
| | - Lars Hubatsch
- The Francis Crick Institute, London, UK
- Institute for the Physics of Living Systems, University College London, London, UK
| | - Jessica McQuade
- Department of Life Sciences, Imperial College London, London, UK
| | - Robert G. Endres
- Department of Life Sciences, Imperial College London, London, UK
| | - Nathan W. Goehring
- The Francis Crick Institute, London, UK
- Institute for the Physics of Living Systems, University College London, London, UK
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Foo S, Cazenave-Gassiot A, Wenk MR, Oliferenko S. Diacylglycerol at the inner nuclear membrane fuels nuclear envelope expansion in closed mitosis. J Cell Sci 2023; 136:286881. [PMID: 36695178 DOI: 10.1242/jcs.260568] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2022] [Accepted: 12/22/2022] [Indexed: 01/26/2023] Open
Abstract
Nuclear envelope (NE) expansion must be controlled to maintain nuclear shape and function. The nuclear membrane expands massively during closed mitosis, enabling chromosome segregation within an intact NE. Phosphatidic acid (PA) and diacylglycerol (DG) can both serve as biosynthetic precursors for membrane lipid synthesis. How they are regulated in time and space and what the implications are of changes in their flux for mitotic fidelity are largely unknown. Using genetically encoded PA and DG probes, we show that DG is depleted from the inner nuclear membrane during mitosis in the fission yeast Schizosaccharomyces pombe, but PA does not accumulate, indicating that it is rerouted to membrane synthesis. We demonstrate that DG-to-PA conversion catalyzed by the diacylglycerol kinase Dgk1 (also known as Ptp4) and direct glycerophospholipid synthesis from DG by diacylglycerol cholinephosphotransferase/ethanolaminephosphotransferase Ept1 reinforce NE expansion. We conclude that DG consumption through both the de novo pathway and the Kennedy pathway fuels a spike in glycerophospholipid biosynthesis, controlling NE expansion and, ultimately, mitotic fidelity.
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Affiliation(s)
- Sherman Foo
- The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK.,Randall Centre for Cell and Molecular Biophysics, School of Basic and Medical Biosciences, King's College London, London SE1 1UL, UK
| | - Amaury Cazenave-Gassiot
- Singapore Lipidomics Incubator, Life Sciences Institute and Precision Medicine Translational Research Program, Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, MD7, 8 Medical Drive, 117596 Singapore
| | - Markus R Wenk
- Singapore Lipidomics Incubator, Life Sciences Institute and Precision Medicine Translational Research Program, Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, MD7, 8 Medical Drive, 117596 Singapore
| | - Snezhana Oliferenko
- The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK.,Randall Centre for Cell and Molecular Biophysics, School of Basic and Medical Biosciences, King's College London, London SE1 1UL, UK
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Ng K, Bland T, Hirani N, Goehring NW. An analog sensitive allele permits rapid and reversible chemical inhibition of PKC-3 activity in C. elegans. MICROPUBLICATION BIOLOGY 2022; 2022:10.17912/micropub.biology.000610. [PMID: 35996692 PMCID: PMC9391946 DOI: 10.17912/micropub.biology.000610] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Revised: 07/27/2022] [Accepted: 08/04/2022] [Indexed: 11/18/2022]
Abstract
Engineered analog sensitive kinases provide a highly effective method for acute, controllable, and highly selective inhibition of kinase activity. Here we describe the design and characterization of an analog sensitive allele of the polarity kinase, PKC-3. This allele supports normal function as measured by its ability to exclude PAR-2 from the anterior membrane of zygotes, and is rapidly and reversibly inhibited in a dose-dependent manner by the ATP analog 1NA-PP1. This allele provides a new tool to explore the role of PKC-3 in diverse contexts within C. elegans , particularly those in which acute and reversible control of PKC-3 kinase activity may be desired.
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Affiliation(s)
- KangBo Ng
- Francis Crick Institute, London, NW1 1AT, UK
,
Institute for the Physics of Living Systems, University College London, WC1E 6BT, UK
| | - Tom Bland
- Francis Crick Institute, London, NW1 1AT, UK
,
Institute for the Physics of Living Systems, University College London, WC1E 6BT, UK
| | | | - Nathan W. Goehring
- Francis Crick Institute, London, NW1 1AT, UK
,
Institute for the Physics of Living Systems, University College London, WC1E 6BT, UK
,
Correspondence to: Nathan W. Goehring (
)
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