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Nguyen JMK, Liu Y, Nguyen L, Sidhaye VK, Robinson DN. Discovery and Quantitative Dissection of Cytokinesis Mechanisms Using Dictyostelium discoideum. Methods Mol Biol 2024; 2814:1-27. [PMID: 38954194 DOI: 10.1007/978-1-0716-3894-1_1] [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] [Indexed: 07/04/2024]
Abstract
The social amoeba Dictyostelium discoideum is a versatile model for understanding many different cellular processes involving cell motility including chemotaxis, phagocytosis, and cytokinesis. Cytokinesis, in particular, is a model cell-shaped change process in which a cell separates into two daughter cells. D. discoideum has been used extensively to identify players in cytokinesis and understand how they comprise the mechanosensory and biochemical pathways of cytokinesis. In this chapter, we describe how we use cDNA library complementation with D. discoideum to discover potential regulators of cytokinesis. Once identified, these regulators are further analyzed through live cell imaging, immunofluorescence imaging, fluorescence correlation and cross-correlation spectroscopy, micropipette aspiration, and fluorescence recovery after photobleaching. Collectively, these methods aid in detailing the mechanisms and signaling pathways that comprise cell division.
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Affiliation(s)
- Jennifer M K Nguyen
- Department of Cell Biology, Johns Hopkins School of Medicine, Baltimore, MD, USA
- Department of Pharmacology of Molecular Sciences, Johns Hopkins School of Medicine, Baltimore, MD, USA
| | - Yinan Liu
- Department of Cell Biology, Johns Hopkins School of Medicine, Baltimore, MD, USA
- Department of Pharmacology of Molecular Sciences, Johns Hopkins School of Medicine, Baltimore, MD, USA
| | - Ly Nguyen
- Department of Cell Biology, Johns Hopkins School of Medicine, Baltimore, MD, USA
| | | | - Douglas N Robinson
- Department of Cell Biology, Johns Hopkins School of Medicine, Baltimore, MD, USA.
- Department of Pharmacology of Molecular Sciences, Johns Hopkins School of Medicine, Baltimore, MD, USA.
- Department of Medicine, Johns Hopkins School of Medicine, Baltimore, MD, USA.
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Plaza-Rodríguez AI, Nguyen LTS, Robinson DN, Iglesias PA. Particle-based model of mechanosensory contractility kit assembly. Biophys J 2022; 121:4600-4614. [PMID: 36273263 PMCID: PMC9748368 DOI: 10.1016/j.bpj.2022.10.031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Revised: 06/10/2022] [Accepted: 10/20/2022] [Indexed: 12/15/2022] Open
Abstract
Cell shape change processes, such as proliferation, polarization, migration, and cancer metastasis, rely on a dynamic network of macromolecules. The proper function of this network enables mechanosensation, the ability of cells to sense and respond to mechanical cues. Myosin II and cortexillin I, critical elements of the cellular mechanosensory machinery, preassemble in the cytoplasm of Dictyostelium cells into complexes that we have termed contractility kits (CKs). Two IQGAP proteins then differentially regulate the mechanoresponsiveness of the cortexillin I-myosin II elements within CKs. To investigate the mechanism of CK self-assembly and gain insight into possible molecular means for IQGAP regulation, we developed a coarse-grained excluded volume molecular model in which all protein polymers are represented by nm-sized spheres connected by spring-like links. The model is parameterized using experimentally measured parameters acquired through fluorescence cross-correlation spectroscopy and fluorescence correlation spectroscopy, which describe the interaction affinities and diffusion coefficients for individual molecular components, and which have also been validated via several orthogonal methods. Simulations of wild-type and null-mutant conditions implied that the temporal order of assembly of these kits is dominated by myosin II dimer formation and that IQGAP proteins mediate cluster growth. In addition, our simulations predicted the existence of "ambiguous" CKs that incorporate both classes of IQGAPs, and we confirmed this experimentally using fluorescence cross-correlation spectroscopy. The model serves to describe the formation of the CKs and how their assembly enables and regulates mechanosensation at the molecular level.
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Affiliation(s)
| | - Ly T S Nguyen
- Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Douglas N Robinson
- Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Pablo A Iglesias
- Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, Maryland; Department of Electrical & Computer Engineering, Johns Hopkins University Whiting School of Engineering, Baltimore, Maryland.
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Nguyen LTS, Robinson DN. The lectin Discoidin I acts in the cytoplasm to help assemble the contractile machinery. J Cell Biol 2022; 221:213504. [PMID: 36165849 PMCID: PMC9523886 DOI: 10.1083/jcb.202202063] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2022] [Revised: 06/11/2022] [Accepted: 08/09/2022] [Indexed: 11/22/2022] Open
Abstract
Cellular functions, such as division and migration, require cells to undergo robust shape changes. Through their contractility machinery, cells also sense, respond, and adapt to their physical surroundings. In the cytoplasm, the contractility machinery organizes into higher order assemblies termed contractility kits (CKs). Using Dictyostelium discoideum, we previously identified Discoidin I (DscI), a classic secreted lectin, as a CK component through its physical interactions with the actin crosslinker Cortexillin I (CortI) and the scaffolding protein IQGAP2. Here, we find that DscI ensures robust cytokinesis through regulating intracellular components of the contractile machinery. Specifically, DscI is necessary for normal cytokinesis, cortical tension, membrane-cortex connections, and cortical distribution and mechanoresponsiveness of CortI. The dscI deletion mutants also have complex genetic epistatic relationships with CK components, acting as a genetic suppressor of cortI and iqgap1, but as an enhancer of iqgap2. This work underscores the fact that proteins like DiscI contribute in diverse ways to the activities necessary for optimal cell function.
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Affiliation(s)
- Ly T S Nguyen
- Department of Cell Biology, School of Medicine, Johns Hopkins University, Baltimore, MD
| | - Douglas N Robinson
- Department of Cell Biology, School of Medicine, Johns Hopkins University, Baltimore, MD
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Schiffhauer ES, Ren Y, Iglesias VA, Kothari P, Iglesias PA, Robinson DN. Myosin IIB assembly state determines its mechanosensitive dynamics. J Cell Biol 2019; 218:895-908. [PMID: 30655296 PMCID: PMC6400566 DOI: 10.1083/jcb.201806058] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2018] [Revised: 11/20/2018] [Accepted: 12/19/2018] [Indexed: 11/22/2022] Open
Abstract
Dynamical cell shape changes require a highly sensitive cellular system that can respond to chemical and mechanical inputs. Myosin IIs are key players in the cell's ability to react to mechanical inputs, demonstrating an ability to accumulate in response to applied stress. Here, we show that inputs that influence the ability of myosin II to assemble into filaments impact the ability of myosin to respond to stress in a predictable manner. Using mathematical modeling for Dictyostelium myosin II, we predict that myosin II mechanoresponsiveness will be biphasic with an optimum established by the percentage of myosin II assembled into bipolar filaments. In HeLa and NIH 3T3 cells, heavy chain phosphorylation of NMIIB by PKCζ, as well as expression of NMIIA, can control the ability of NMIIB to mechanorespond by influencing its assembly state. These data demonstrate that multiple inputs to the myosin II assembly state integrate at the level of myosin II to govern the cellular response to mechanical inputs.
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Affiliation(s)
- Eric S Schiffhauer
- Department of Cell Biology, School of Medicine, Johns Hopkins University, Baltimore, MD
| | - Yixin Ren
- Department of Cell Biology, School of Medicine, Johns Hopkins University, Baltimore, MD
| | - Vicente A Iglesias
- Department of Electrical and Computer Engineering, Whiting School of Engineering, Johns Hopkins University, Baltimore, MD
| | - Priyanka Kothari
- Department of Cell Biology, School of Medicine, Johns Hopkins University, Baltimore, MD
| | - Pablo A Iglesias
- Department of Cell Biology, School of Medicine, Johns Hopkins University, Baltimore, MD.,Department of Electrical and Computer Engineering, Whiting School of Engineering, Johns Hopkins University, Baltimore, MD
| | - Douglas N Robinson
- Department of Cell Biology, School of Medicine, Johns Hopkins University, Baltimore, MD .,Department of Pharmacology and Molecular Sciences School of Medicine, Johns Hopkins University, Baltimore, MD.,Department of Medicine, School of Medicine, Johns Hopkins University, Baltimore, MD.,Department of Chemical and Biomolecular Engineering, Whiting School of Engineering, Johns Hopkins University, Baltimore, MD
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Kothari P, Srivastava V, Aggarwal V, Tchernyshyov I, Van Eyk JE, Ha T, Robinson DN. Contractility kits promote assembly of the mechanoresponsive cytoskeletal network. J Cell Sci 2019; 132:jcs.226704. [PMID: 30559246 DOI: 10.1242/jcs.226704] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2018] [Accepted: 12/05/2018] [Indexed: 01/19/2023] Open
Abstract
Cellular contractility is governed by a control system of proteins that integrates internal and external cues to drive diverse shape change processes. This contractility controller includes myosin II motors, actin crosslinkers and protein scaffolds, which exhibit robust and cooperative mechanoaccumulation. However, the biochemical interactions and feedback mechanisms that drive the controller remain unknown. Here, we use a proteomics approach to identify direct interactors of two key nodes of the contractility controller in the social amoeba Dictyostelium discoideum: the actin crosslinker cortexillin I and the scaffolding protein IQGAP2. We highlight several unexpected proteins that suggest feedback from metabolic and RNA-binding proteins on the contractility controller. Quantitative in vivo biochemical measurements reveal direct interactions between myosin II and cortexillin I, which form the core mechanosensor. Furthermore, IQGAP1 negatively regulates mechanoresponsiveness by competing with IQGAP2 for binding the myosin II-cortexillin I complex. These myosin II-cortexillin I-IQGAP2 complexes are pre-assembled into higher-order mechanoresponsive contractility kits (MCKs) that are poised to integrate into the cortex upon diffusional encounter coincident with mechanical inputs.This article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
- Priyanka Kothari
- Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Vasudha Srivastava
- Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.,Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Vasudha Aggarwal
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Irina Tchernyshyov
- Department of Medicine, The Smidt Heart Institute and Advanced Clinical Biosystems Institute, Cedar-Sinai Medical Center, Los Angeles, CA 90048, USA
| | - Jennifer E Van Eyk
- Department of Medicine, The Smidt Heart Institute and Advanced Clinical Biosystems Institute, Cedar-Sinai Medical Center, Los Angeles, CA 90048, USA
| | - Taekjip Ha
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.,Department of Biophysics, Johns Hopkins University, Baltimore, MD 21218, USA.,Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD 21205, USA.,Howard Hughes Medical Institute, Baltimore, MD 21205, USA
| | - Douglas N Robinson
- Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA .,Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, MD 21218, USA.,Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.,Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
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West-Foyle H, Kothari P, Osborne J, Robinson DN. 14-3-3 proteins tune non-muscle myosin II assembly. J Biol Chem 2018; 293:6751-6761. [PMID: 29549125 DOI: 10.1074/jbc.m117.819391] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2017] [Revised: 03/12/2018] [Indexed: 11/06/2022] Open
Abstract
The 14-3-3 family comprises a group of small proteins that are essential, ubiquitous, and highly conserved across eukaryotes. Overexpression of the 14-3-3 proteins σ, ϵ, ζ, and η correlates with high metastatic potential in multiple cancer types. In Dictyostelium, 14-3-3 promotes myosin II turnover in the cell cortex and modulates cortical tension, cell shape, and cytokinesis. In light of the important roles of 14-3-3 proteins across a broad range of eukaryotic species, we sought to determine how 14-3-3 proteins interact with myosin II. Here, conducting in vitro and in vivo studies of both Dictyostelium (one 14-3-3 and one myosin II) and human proteins (seven 14-3-3s and three nonmuscle myosin IIs), we investigated the mechanism by which 14-3-3 proteins regulate myosin II assembly. Using in vitro assembly assays with purified myosin II tail fragments and 14-3-3, we demonstrate that this interaction is direct and phosphorylation-independent. All seven human 14-3-3 proteins also altered assembly of at least one paralog of myosin II. Our findings indicate a mechanism of myosin II assembly regulation that is mechanistically conserved across a billion years of evolution from amebas to humans. We predict that altered 14-3-3 expression in humans inhibits the tumor suppressor myosin II, contributing to the changes in cell mechanics observed in many metastatic cancers.
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Affiliation(s)
| | | | | | - Douglas N Robinson
- From the Departments of Cell Biology, .,Pharmacology and Molecular Sciences, and.,Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
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