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Lin CC, Suen KM, Lidster J, Ladbury JE. The emerging role of receptor tyrosine kinase phase separation in cancer. Trends Cell Biol 2024; 34:371-379. [PMID: 37777392 DOI: 10.1016/j.tcb.2023.09.002] [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: 05/30/2023] [Revised: 08/17/2023] [Accepted: 09/06/2023] [Indexed: 10/02/2023]
Abstract
Receptor tyrosine kinase (RTK)-mediated signal transduction is fundamental to cell function and drives important cellular outcomes which, when dysregulated, can lead to malignant tumour growth and metastasis. The initiation of signals from plasma membrane-bound RTKs is subjected to multiple regulatory mechanisms that control downstream effector protein recruitment and function. The high propensity of RTKs to condense via liquid-liquid phase separation (LLPS) into membraneless organelles with downstream effector proteins provides a further fundamental mechanism for signal regulation. Herein we highlight how this phenomenon contributes to cancer signalling and consider the potential impact of LLPS on outcomes for cancer patients.
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Affiliation(s)
- Chi-Chuan Lin
- School of Molecular and Cellular Biology, University of Leeds, Leeds, LS2 9JT, UK.
| | - Kin Man Suen
- School of Molecular and Cellular Biology, University of Leeds, Leeds, LS2 9JT, UK
| | - Jessica Lidster
- School of Molecular and Cellular Biology, University of Leeds, Leeds, LS2 9JT, UK
| | - John E Ladbury
- School of Molecular and Cellular Biology, University of Leeds, Leeds, LS2 9JT, UK.
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Baig MS, Barmpoutsi S, Bharti S, Weigert A, Hirani N, Atre R, Khabiya R, Sharma R, Sarup S, Savai R. Adaptor molecules mediate negative regulation of macrophage inflammatory pathways: a closer look. Front Immunol 2024; 15:1355012. [PMID: 38482001 PMCID: PMC10933033 DOI: 10.3389/fimmu.2024.1355012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2023] [Accepted: 01/22/2024] [Indexed: 04/13/2024] Open
Abstract
Macrophages play a central role in initiating, maintaining, and terminating inflammation. For that, macrophages respond to various external stimuli in changing environments through signaling pathways that are tightly regulated and interconnected. This process involves, among others, autoregulatory loops that activate and deactivate macrophages through various cytokines, stimulants, and other chemical mediators. Adaptor proteins play an indispensable role in facilitating various inflammatory signals. These proteins are dynamic and flexible modulators of immune cell signaling and act as molecular bridges between cell surface receptors and intracellular effector molecules. They are involved in regulating physiological inflammation and also contribute significantly to the development of chronic inflammatory processes. This is at least partly due to their involvement in the activation and deactivation of macrophages, leading to changes in the macrophages' activation/phenotype. This review provides a comprehensive overview of the 20 adaptor molecules and proteins that act as negative regulators of inflammation in macrophages and effectively suppress inflammatory signaling pathways. We emphasize the functional role of adaptors in signal transduction in macrophages and their influence on the phenotypic transition of macrophages from pro-inflammatory M1-like states to anti-inflammatory M2-like phenotypes. This endeavor mainly aims at highlighting and orchestrating the intricate dynamics of adaptor molecules by elucidating the associated key roles along with respective domains and opening avenues for therapeutic and investigative purposes in clinical practice.
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Affiliation(s)
- Mirza S. Baig
- Department of Biosciences and Biomedical Engineering (BSBE), Indian Institute of Technology Indore (IITI), Indore, India
| | - Spyridoula Barmpoutsi
- Lung Microenvironmental Niche in Cancerogenesis, Institute for Lung Health (ILH), Justus Liebig University, Giessen, Germany
- Max Planck Institute for Heart and Lung Research, Member of the German Center for Lung Research (DZL), Member of the Cardio-Pulmonary Institute (CPI), Bad Nauheim, Germany
| | - Shreya Bharti
- Department of Biosciences and Biomedical Engineering (BSBE), Indian Institute of Technology Indore (IITI), Indore, India
| | - Andreas Weigert
- Institute of Biochemistry I, Faculty of Medicine, Goethe University Frankfurt, Frankfurt, Germany
- Frankfurt Cancer Institute (FCI), Goethe University Frankfurt, Frankfurt, Germany
| | - Nik Hirani
- MRC Centre for Inflammation Research, Queen’s Medical Research Institute, University of Edinburgh, Edinburgh, United Kingdom
| | - Rajat Atre
- Department of Biosciences and Biomedical Engineering (BSBE), Indian Institute of Technology Indore (IITI), Indore, India
| | - Rakhi Khabiya
- Department of Biosciences and Biomedical Engineering (BSBE), Indian Institute of Technology Indore (IITI), Indore, India
| | - Rahul Sharma
- Department of Biosciences and Biomedical Engineering (BSBE), Indian Institute of Technology Indore (IITI), Indore, India
| | - Shivmuni Sarup
- Department of Biosciences and Biomedical Engineering (BSBE), Indian Institute of Technology Indore (IITI), Indore, India
| | - Rajkumar Savai
- Lung Microenvironmental Niche in Cancerogenesis, Institute for Lung Health (ILH), Justus Liebig University, Giessen, Germany
- Max Planck Institute for Heart and Lung Research, Member of the German Center for Lung Research (DZL), Member of the Cardio-Pulmonary Institute (CPI), Bad Nauheim, Germany
- Frankfurt Cancer Institute (FCI), Goethe University Frankfurt, Frankfurt, Germany
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Peng WY, Abere B, Shi H, Toland S, Smithgall TE, Moore PS, Chang Y. Membrane-bound Merkel cell polyomavirus middle T protein constitutively activates PLCγ1 signaling through Src-family kinases. Proc Natl Acad Sci U S A 2023; 120:e2316467120. [PMID: 38079542 PMCID: PMC10740393 DOI: 10.1073/pnas.2316467120] [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: 09/21/2023] [Accepted: 11/11/2023] [Indexed: 12/18/2023] Open
Abstract
Merkel cell polyomavirus (MCV or MCPyV) is an alphapolyomavirus causing human Merkel cell carcinoma and encodes four tumor (T) antigen proteins: large T (LT), small tumor (sT), 57 kT, and middle T (MT)/alternate LT open reading frame proteins. We show that MCV MT is generated as multiple isoforms through internal methionine translational initiation that insert into membrane lipid rafts. The membrane-localized MCV MT oligomerizes and promiscuously binds to lipid raft-associated Src family kinases (SFKs). MCV MT-SFK interaction is mediated by a Src homology (SH) 3 recognition motif as determined by surface plasmon resonance, coimmunoprecipitation, and bimolecular fluorescence complementation assays. SFK recruitment by MT leads to tyrosine phosphorylation at a SH2 recognition motif (pMTY114), allowing interaction with phospholipase C gamma 1 (PLCγ1). The secondary recruitment of PLCγ1 to the SFK-MT membrane complex promotes PLCγ1 tyrosine phosphorylation on Y783 and activates the NF-κB inflammatory signaling pathway. Mutations at either the MCV MT SH2 or SH3 recognition sites abrogate PLCγ1-dependent activation of NF-κB signaling and increase viral replication after MCV genome transfection into 293 cells. These findings reveal a conserved viral targeting of the SFK-PLCγ1 pathway by both MCV and murine polyomavirus (MuPyV) MT proteins. The molecular steps in how SFK-PLCγ1 activation is achieved, however, differ between these two viruses.
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Affiliation(s)
- Wen-Yu Peng
- School of Medicine, Tsinghua University, Beijing100084, China
- Cancer Virology Program, Hillman Cancer Center, University of Pittsburgh, Pittsburgh, PA15213
| | - Bizunesh Abere
- Cancer Virology Program, Hillman Cancer Center, University of Pittsburgh, Pittsburgh, PA15213
- Department of Microbiology and Molecular Genetics, University of Pittsburgh, Pittsburgh, PA15219
| | - Haibin Shi
- Department of Microbiology and Molecular Genetics, University of Pittsburgh, Pittsburgh, PA15219
| | - Sabrina Toland
- Cancer Virology Program, Hillman Cancer Center, University of Pittsburgh, Pittsburgh, PA15213
| | - Thomas E. Smithgall
- Cancer Virology Program, Hillman Cancer Center, University of Pittsburgh, Pittsburgh, PA15213
- Department of Microbiology and Molecular Genetics, University of Pittsburgh, Pittsburgh, PA15219
| | - Patrick S. Moore
- Cancer Virology Program, Hillman Cancer Center, University of Pittsburgh, Pittsburgh, PA15213
- Department of Microbiology and Molecular Genetics, University of Pittsburgh, Pittsburgh, PA15219
| | - Yuan Chang
- Cancer Virology Program, Hillman Cancer Center, University of Pittsburgh, Pittsburgh, PA15213
- Department of Pathology, University of Pittsburgh, Pittsburgh, PA15213
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Ladbury JE, Lin CC, Suen KM. Phase separation enhances probability of receptor signalling and drug targeting. Trends Biochem Sci 2023; 48:428-436. [PMID: 36759237 DOI: 10.1016/j.tibs.2023.01.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Revised: 01/10/2023] [Accepted: 01/17/2023] [Indexed: 02/10/2023]
Abstract
The probability of a given receptor tyrosine kinase (RTK) triggering a defined cellular outcome is low because of the promiscuous nature of signalling, the randomness of molecular diffusion through the cell, and the ongoing nonfunctional submembrane signalling activity or noise. Signal transduction is therefore a 'numbers game', where enough cell surface receptors and effector proteins must initially be engaged to guarantee formation of a functional signalling complex against a background of redundant events. The presence of intracellular liquid-liquid phase separation (LLPS) at the plasma membrane provides a mechanism through which the probabilistic nature of signalling can be weighted in favour of the required, discrete cellular outcome and mutual exclusivity in signal initiation.
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Affiliation(s)
- John E Ladbury
- School of Molecular and Cellular Biology, University of Leeds, Leeds, LS2 9JT, UK.
| | - Chi-Chuan Lin
- School of Molecular and Cellular Biology, University of Leeds, Leeds, LS2 9JT, UK
| | - Kin Man Suen
- School of Molecular and Cellular Biology, University of Leeds, Leeds, LS2 9JT, UK
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Robinson MJ, Newbury S, Singh K, Leonenko Z, Beazely MA. The Interplay Between Cholesterol and Amyloid-β on HT22 Cell Viability, Morphology, and Receptor Tyrosine Kinase Signaling. J Alzheimers Dis 2023; 96:1663-1683. [PMID: 38073391 DOI: 10.3233/jad-230753] [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: 12/18/2023]
Abstract
BACKGROUND There is a lack of understanding in the molecular and cellular mechanisms of Alzheimer's disease that has hindered progress on therapeutic development. The focus has been on targeting toxic amyloid-β (Aβ) pathology, but these therapeutics have generally failed in clinical trials. Aβ is an aggregation-prone protein that has been shown to disrupt cell membrane structure in molecular biophysics studies and interfere with membrane receptor signaling in cell and animal studies. Whether the lipid membrane or specific receptors are the primary target of attack has not been determined. OBJECTIVE This work elucidates some of the interplay between membrane cholesterol and Aβ42 on HT22 neuronal cell viability, morphology, and platelet-derived growth factor (PDGF) signaling pathways. METHODS The effects of cholesterol depletion by methyl-β-cyclodextrin followed by treatment with Aβ and/or PDGF-AA were assessed by MTT cell viability assays, western blot, optical and AFM microscopy. RESULTS Cell viability studies show that cholesterol depletion was mildly protective against Aβ toxicity. Together cholesterol reduction and Aβ42 treatment compounded the disruption of the PDGFα receptor activation. Phase contrast optical microscopy and live cell atomic force microscopy imaging revealed that cytotoxic levels of Aβ42 caused morphological changes including cell membrane damage, cytoskeletal disruption, and impaired cell adhesion; cell damage was ameliorated by cellular cholesterol depletion. CONCLUSIONS Cholesterol depletion impacted the effects of Aβ42 on HT22 cell viability, morphology, and receptor tyrosine kinase signaling.
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Affiliation(s)
- Morgan J Robinson
- School of Pharmacy, University of Waterloo, Waterloo, ON, Canada
- Waterloo Institute for Nanotechnology, University of Waterloo, Waterloo, ON, Canada
| | - Sean Newbury
- School of Pharmacy, University of Waterloo, Waterloo, ON, Canada
| | - Kartar Singh
- School of Pharmacy, University of Waterloo, Waterloo, ON, Canada
| | - Zoya Leonenko
- Department of Biology, University of Waterloo, Waterloo, ON, Canada
- Department of Physics and Astronomy, University of Waterloo, Waterloo, ON, Canada
- Waterloo Institute for Nanotechnology, University of Waterloo, Waterloo, ON, Canada
| | - Michael A Beazely
- School of Pharmacy, University of Waterloo, Waterloo, ON, Canada
- Department of Biology, University of Waterloo, Waterloo, ON, Canada
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The structural basis of BCR-ABL recruitment of GRB2 in chronic myelogenous leukemia. Biophys J 2022; 121:2251-2265. [PMID: 35651316 DOI: 10.1016/j.bpj.2022.05.030] [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: 01/21/2022] [Revised: 04/24/2022] [Accepted: 05/20/2022] [Indexed: 11/21/2022] Open
Abstract
BCR-ABL drives chronic myeloid leukemia (CML). BCR binding to GRB2 transduces signaling via the Ras/MAPK pathway. Despite considerable data confirming the binding, molecular-level understanding of exactly how the two proteins interact, and especially, what are the determinants of the specificity of the SH2GRB2 domain-pBCR recognition are still open questions. Yet, this is vastly important for understanding binding selectivity, and for predicting the phosphorylated receptors, or peptides, that are likely to bind. Here, we uncover these determinants and ascertain to what extent they relate to the affinity of the interaction. Toward this end, we modeled the complexes of the phosphorylated BCR (pBCR) and SH2GRB2 and other pY/Y-peptide-SH2 complexes and compared their specificity and affinity. We observed that pBCR's 176FpYVNV180 motif is favorable and specific to SH2GRB2, similar to pEGFR, but not other complexes. SH2GRB2 contains two binding pockets: pY-binding recognition pocket triggers binding, and the specificity pocket whose interaction is governed by N179 in pBCR and W121 in SH2GRB2. Our proposed motif with optimal affinity to SH2GRB2 is E/D-pY-E/V-N-I/L. Collectively, we provide the structural basis of BCR-ABL recruitment of GRB2, outline its specificity hallmarks, and delineate a blueprint for prediction of BCR-binding scaffolds and for therapeutic peptide design.
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