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Ball NJ, Barnett SFH, Goult BT. Mechanically operated signalling scaffolds. Biochem Soc Trans 2024; 52:517-527. [PMID: 38572868 PMCID: PMC11088903 DOI: 10.1042/bst20221194] [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: 01/03/2024] [Revised: 03/20/2024] [Accepted: 03/25/2024] [Indexed: 04/05/2024]
Abstract
Cellular signalling is a complex process and involves cascades of enzymes that, in response to a specific signal, give rise to exact cellular responses. Signalling scaffold proteins organise components of these signalling pathways in space and time to co-ordinate signalling outputs. In this review we introduce a new class of mechanically operated signalling scaffolds that are built into the cytoskeletal architecture of the cell. These proteins contain force-dependent binary switch domains that integrate chemical and mechanical signals to introduce quantised positional changes to ligands and persistent alterations in cytoskeletal architecture providing mechanomemory capabilities. We focus on the concept of spatial organisation, and how the cell organises signalling molecules at the plasma membrane in response to specific signals to create order and distinct signalling outputs. The dynamic positioning of molecules using binary switches adds an additional layer of complexity to the idea of scaffolding. The switches can spatiotemporally organise enzymes and substrates dynamically, with the introduction of ∼50 nm quantised steps in distance between them as the switch patterns change. Together these different types of signalling scaffolds and the proteins engaging them, provide a way for an ordering of molecules that extends beyond current views of the cell.
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Affiliation(s)
- Neil J. Ball
- Department of Biochemistry, Cell and Systems Biology, Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Crown Street, Liverpool L69 7ZB, U.K
| | | | - Benjamin T. Goult
- Department of Biochemistry, Cell and Systems Biology, Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Crown Street, Liverpool L69 7ZB, U.K
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Guo Y, Yan J, Goult BT. Mechanotransduction through protein stretching. Curr Opin Cell Biol 2024; 87:102327. [PMID: 38301379 DOI: 10.1016/j.ceb.2024.102327] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2023] [Revised: 01/08/2024] [Accepted: 01/08/2024] [Indexed: 02/03/2024]
Abstract
Cells sense and respond to subtle changes in their physicality, and via a myriad of different mechanosensitive processes, convert these physical cues into chemical and biochemical signals. This process, called mechanotransduction, is possible due to a highly sophisticated machinery within cells. One mechanism by which this can occur is via the stretching of mechanosensitive proteins. Stretching proteins that contain force-dependent regions results in altered geometry and dimensions of the connections, as well as differential spatial organization of signals bound to the stretched protein. The purpose of this mini-review is to discuss some of the intense recent activity in this area of mechanobiology that strives to understand how protein stretching can influence signaling outputs and cellular responses.
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Affiliation(s)
- Yanyu Guo
- Department of Physics, Mechanobiology Institute, National University of Singapore 117542, Singapore
| | - Jie Yan
- Department of Physics, Mechanobiology Institute, National University of Singapore 117542, Singapore.
| | - Benjamin T Goult
- School of Biosciences, University of Kent, Canterbury, Kent, CT2 7NJ, UK; Department of Biochemistry, Cell & Systems Biology, Institute of Systems, Molecular & Integrative Biology, University of Liverpool, Crown Street, Liverpool L69 7ZB, UK.
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Kang M, Otani Y, Guo Y, Yan J, Goult BT, Howe AK. The focal adhesion protein talin is a mechanically gated A-kinase anchoring protein. Proc Natl Acad Sci U S A 2024; 121:e2314947121. [PMID: 38513099 PMCID: PMC10990152 DOI: 10.1073/pnas.2314947121] [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: 08/29/2023] [Accepted: 02/22/2024] [Indexed: 03/23/2024] Open
Abstract
Protein kinase A (PKA) is a ubiquitous, promiscuous kinase whose activity is specified through subcellular localization mediated by A-kinase anchoring proteins (AKAPs). PKA has complex roles as both an effector and a regulator of integrin-mediated cell adhesion to extracellular matrix (ECM). Recent observations demonstrate that PKA is an active component of focal adhesions (FA), suggesting the existence of one or more FA AKAPs. Using a promiscuous biotin ligase fused to PKA type-IIα regulatory (RIIα) subunits and subcellular fractionation, we identify the archetypal FA protein talin1 as an AKAP. Talin is a large, mechanosensitive scaffold that directly links integrins to actin filaments and promotes FA assembly by recruiting additional components in a force-dependent manner. The rod region of talin1 consists of 62 α-helices bundled into 13 rod domains, R1 to R13. Direct binding assays and NMR spectroscopy identify helix41 in the R9 subdomain of talin as the PKA binding site. PKA binding to helix41 requires unfolding of the R9 domain, which requires the linker region between R9 and R10. Experiments with single molecules and in cells manipulated to alter actomyosin contractility demonstrate that the PKA-talin interaction is regulated by mechanical force across the talin molecule. Finally, talin mutations that disrupt PKA binding also decrease levels of total and phosphorylated PKA RII subunits as well as phosphorylation of VASP, a known PKA substrate, within FA. These observations identify a mechanically gated anchoring protein for PKA, a force-dependent binding partner for talin1, and a potential pathway for adhesion-associated mechanotransduction.
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Affiliation(s)
- Mingu Kang
- Department of Pharmacology, University of Vermont Larner College of Medicine, Burlington, VT05405
- Department of Molecular Physiology and Biophysics, University of Vermont Larner College of Medicine, Burlington, VT05405
- University of Vermont Cancer Center, Burlington, VT05405
| | - Yasumi Otani
- School of Biosciences, University of Kent, Canterbury, KentCT2 7NJ, United Kingdom
- Department of Biochemistry, Cell and Systems Biology, Institute of Systems, Molecular and Integrative Biology, University of Liverpool, LiverpoolL69 7ZB, United Kingdom
| | - Yanyu Guo
- Department of Physics, Mechanobiology Institute, National University of Singapore, Singapore117542, Singapore
| | - Jie Yan
- Department of Physics, Mechanobiology Institute, National University of Singapore, Singapore117542, Singapore
| | - Benjamin T. Goult
- School of Biosciences, University of Kent, Canterbury, KentCT2 7NJ, United Kingdom
- Department of Biochemistry, Cell and Systems Biology, Institute of Systems, Molecular and Integrative Biology, University of Liverpool, LiverpoolL69 7ZB, United Kingdom
| | - Alan K. Howe
- Department of Pharmacology, University of Vermont Larner College of Medicine, Burlington, VT05405
- Department of Molecular Physiology and Biophysics, University of Vermont Larner College of Medicine, Burlington, VT05405
- University of Vermont Cancer Center, Burlington, VT05405
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Honasoge KS, Karagöz Z, Goult BT, Wolfenson H, LaPointe VLS, Carlier A. Force-dependent focal adhesion assembly and disassembly: A computational study. PLoS Comput Biol 2023; 19:e1011500. [PMID: 37801464 PMCID: PMC10584152 DOI: 10.1371/journal.pcbi.1011500] [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: 02/07/2023] [Revised: 10/18/2023] [Accepted: 09/07/2023] [Indexed: 10/08/2023] Open
Abstract
Cells interact with the extracellular matrix (ECM) via cell-ECM adhesions. These physical interactions are transduced into biochemical signals inside the cell which influence cell behaviour. Although cell-ECM interactions have been studied extensively, it is not completely understood how immature (nascent) adhesions develop into mature (focal) adhesions and how mechanical forces influence this process. Given the small size, dynamic nature and short lifetimes of nascent adhesions, studying them using conventional microscopic and experimental techniques is challenging. Computational modelling provides a valuable resource for simulating and exploring various "what if?" scenarios in silico and identifying key molecular components and mechanisms for further investigation. Here, we present a simplified mechano-chemical model based on ordinary differential equations with three major proteins involved in adhesions: integrins, talin and vinculin. Additionally, we incorporate a hypothetical signal molecule that influences adhesion (dis)assembly rates. We find that assembly and disassembly rates need to vary dynamically to limit maturation of nascent adhesions. The model predicts biphasic variation of actin retrograde velocity and maturation fraction with substrate stiffness, with maturation fractions between 18-35%, optimal stiffness of ∼1 pN/nm, and a mechanosensitive range of 1-100 pN/nm, all corresponding to key experimental findings. Sensitivity analyses show robustness of outcomes to small changes in parameter values, allowing model tuning to reflect specific cell types and signaling cascades. The model proposes that signal-dependent disassembly rate variations play an underappreciated role in maturation fraction regulation, which should be investigated further. We also provide predictions on the changes in traction force generation under increased/decreased vinculin concentrations, complementing previous vinculin overexpression/knockout experiments in different cell types. In summary, this work proposes a model framework to robustly simulate the mechanochemical processes underlying adhesion maturation and maintenance, thereby enhancing our fundamental knowledge of cell-ECM interactions.
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Affiliation(s)
- Kailas Shankar Honasoge
- Department of Cell Biology–Inspired Tissue Engineering, MERLN Institute for Technology-Inspired Regenerative Medicine, Maastricht University, Maastricht, the Netherlands
| | - Zeynep Karagöz
- Department of Cell Biology–Inspired Tissue Engineering, MERLN Institute for Technology-Inspired Regenerative Medicine, Maastricht University, Maastricht, the Netherlands
| | - Benjamin T. Goult
- School of Biosciences, University of Kent, Canterbury, United Kingdom
| | - Haguy Wolfenson
- Department of Genetics and Developmental Biology, Rappaport Faculty of Medicine, Technion – Israel Institute of Technology, Haifa, Israel
| | - Vanessa L. S. LaPointe
- Department of Cell Biology–Inspired Tissue Engineering, MERLN Institute for Technology-Inspired Regenerative Medicine, Maastricht University, Maastricht, the Netherlands
| | - Aurélie Carlier
- Department of Cell Biology–Inspired Tissue Engineering, MERLN Institute for Technology-Inspired Regenerative Medicine, Maastricht University, Maastricht, the Netherlands
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Kang M, Otani Y, Guo Y, Yan J, Goult BT, Howe AK. The focal adhesion protein talin is a mechanically-gated A-kinase anchoring protein (AKAP). BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.20.554038. [PMID: 37645895 PMCID: PMC10462126 DOI: 10.1101/2023.08.20.554038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/31/2023]
Abstract
The cAMP-dependent protein kinase (Protein Kinase A; PKA) is a ubiquitous, promiscuous kinase whose activity is focused and specified through subcellular localization mediated by A-kinase anchoring proteins (AKAPs). PKA has complex roles as both an effector and a regulator of integrin-mediated cell adhesion to the extracellular matrix (ECM). Recent observations demonstrate that PKA is an active component of focal adhesions (FA), intracellular complexes coupling ECM-bound integrins to the actin cytoskeleton, suggesting the existence of one or more FA AKAPs. Using a combination of a promiscuous biotin ligase fused to PKA type-IIα regulatory (RIIα) subunits and subcellular fractionation, we identify the archetypal FA protein talin1 as an AKAP. Talin is a large, mechanosensitive scaffold that directly links integrins to actin filaments and promotes FA assembly by recruiting additional components in a force-dependent manner. The rod region of talin1 consists of 62 α-helices bundled into 13 rod domains, R1-R13. Direct binding assays and nuclear magnetic resonance spectroscopy identify helix41 in the R9 subdomain of talin as the PKA binding site. PKA binding to helix41 requires unfolding of the R9 domain, which requires the linker region between R9 and R10. Finally, single-molecule experiments with talin1 and PKA, and experiments in cells manipulated to alter actomyosin contractility demonstrate that the PKA-talin interaction is regulated by mechanical force across the talin molecule. These observations identify the first mechanically-gated anchoring protein for PKA, a new force-dependent binding partner for talin1, and thus a new mechanism for coupling cellular tension and signal transduction.
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