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Shead KD, Salyahetdinova V, Baillie GS. Charting the importance of filamin A posttranslational modifications. Biochem J 2024; 481:865-881. [PMID: 38958472 DOI: 10.1042/bcj20240121] [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: 03/18/2024] [Revised: 06/17/2024] [Accepted: 06/18/2024] [Indexed: 07/04/2024]
Abstract
Filamin A is an essential protein in the cell cytoskeleton because of its actin binding properties and unique homodimer rod-shaped structure, which organises actin into three-dimensional orthogonal networks imperative to cell motility, spreading and adhesion. Filamin A is subject to extensive posttranslational modification (PTM) which serves to co-ordinate cellular architecture and to modulate its large protein-protein interaction network which is key to the protein's role as a cellular signalling hub. Characterised PTMs include phosphorylation, irreversible cleavage, ubiquitin mediated degradation, hydroxylation and O-GlcNAcylation, with preliminary evidence of tyrosylation, carbonylation and acetylation. Each modification and its relation to filamin A function will be described here. These modifications are often aberrantly applied in a range of diseases including, but not limited to, cancer, cardiovascular disease and neurological disease and we discuss the concept of target specific PTMs with novel therapeutic modalities. In summary, our review represents a topical 'one-stop-shop' that enables understanding of filamin A function in cell homeostasis and provides insight into how a variety of modifications add an extra level of Filamin A control.
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Affiliation(s)
- Kyle D Shead
- School of Cardiovascular and Metabolic Health, University of Glasgow, Glasgow G128QQ, U.K
| | - Veneta Salyahetdinova
- School of Cardiovascular and Metabolic Health, University of Glasgow, Glasgow G128QQ, U.K
| | - George S Baillie
- School of Cardiovascular and Metabolic Health, University of Glasgow, Glasgow G128QQ, U.K
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2
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Baumer Y, Pita MA, Turner BS, Baez AS, Ortiz-Whittingham LR, Gutierrez-Huerta CA, Neally SJ, Farmer N, Mitchell VM, Collins BS, Powell-Wiley TM. Neighborhood socioeconomic deprivation and individual-level socioeconomic status are associated with dopamine-mediated changes to monocyte subset CCR2 expression via a cAMP-dependent pathway. Brain Behav Immun Health 2023; 30:100640. [PMID: 37251548 PMCID: PMC10220312 DOI: 10.1016/j.bbih.2023.100640] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2023] [Accepted: 05/12/2023] [Indexed: 05/31/2023] Open
Abstract
Social determinants of health (SDoH) include socioeconomic, environmental, and psychological factors that impact health. Neighborhood socioeconomic deprivation (NSD) and low individual-level socioeconomic status (SES) are SDoH that associate with incident heart failure, stroke, and cardiovascular mortality, but the underlying biological mechanisms are not well understood. Previous research has demonstrated an association between NSD, in particular, and key components of the neural-hematopoietic-axis including amygdala activity as a marker of chronic stress, bone marrow activity, and arterial inflammation. Our study further characterizes the role of NSD and SES as potential sources of chronic stress related to downstream immunological factors in this stress-associated biologic pathway. We investigated how NSD, SES, and catecholamine levels (as proxy for sympathetic nervous system activation) may influence monocytes which are known to play a significant role in atherogenesis. First, in an ex vivo approach, we treated healthy donor monocytes with biobanked serum from a community cohort of African Americans at risk for CVD. Subsequently, the treated monocytes were subjected to flow cytometry for characterization of monocyte subsets and receptor expression. We determined that NSD and serum catecholamines (namely dopamine [DA] and norepinephrine [NE]) associated with monocyte C-C chemokine receptor type 2 (CCR2) expression (p < 0.05), a receptor known to facilitate recruitment of monocytes towards arterial plaques. Additionally, NSD associated with catecholamine levels, especially DA in individuals of low SES. To further explore the potential role of NSD and the effects of catecholamines on monocytes, monocytes were treated in vitro with epinephrine [EPI], NE, or DA. Only DA increased CCR2 expression in a dose-dependent manner (p < 0.01), especially on non-classical monocytes (NCM). Furthermore, linear regression analysis between D2-like receptor surface expression and surface CCR2 expression suggested D2-like receptor signaling in NCM. Indicative of D2-signaling, cAMP levels were found to be lower in DA-treated monocytes compared to untreated controls (control 29.78 pmol/ml vs DA 22.97 pmol/ml; p = 0.038) and the impact of DA on NCM CCR2 expression was abrogated by co-treatment with 8-CPT, a cAMP analog. Furthermore, Filamin A (FLNA), a prominent actin-crosslinking protein, that is known to regulate CCR2 recycling, significantly decreased in DA-treated NCM (p < 0.05), indicating a reduction of CCR2 recycling. Overall, we provide a novel immunological mechanism, driven by DA signaling and CCR2, for how NSD may contribute to atherogenesis. Future studies should investigate the importance of DA in CVD development and progression in populations disproportionately experiencing chronic stress due to SDoH.
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Affiliation(s)
- Yvonne Baumer
- Social Determinants of Obesity and Cardiovascular Risk Laboratory, Cardiovascular Branch, Division of Intramural Research, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Mario A. Pita
- Social Determinants of Obesity and Cardiovascular Risk Laboratory, Cardiovascular Branch, Division of Intramural Research, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Briana S. Turner
- Social Determinants of Obesity and Cardiovascular Risk Laboratory, Cardiovascular Branch, Division of Intramural Research, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Andrew S. Baez
- Social Determinants of Obesity and Cardiovascular Risk Laboratory, Cardiovascular Branch, Division of Intramural Research, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Lola R. Ortiz-Whittingham
- Social Determinants of Obesity and Cardiovascular Risk Laboratory, Cardiovascular Branch, Division of Intramural Research, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Cristhian A. Gutierrez-Huerta
- Social Determinants of Obesity and Cardiovascular Risk Laboratory, Cardiovascular Branch, Division of Intramural Research, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Sam J. Neally
- Social Determinants of Obesity and Cardiovascular Risk Laboratory, Cardiovascular Branch, Division of Intramural Research, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Nicole Farmer
- Translational Biobehavioral and Health Disparities Branch, National Institutes of Health, Clinical Center, Bethesda, MD, USA
| | - Valerie M. Mitchell
- Social Determinants of Obesity and Cardiovascular Risk Laboratory, Cardiovascular Branch, Division of Intramural Research, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Billy S. Collins
- Social Determinants of Obesity and Cardiovascular Risk Laboratory, Cardiovascular Branch, Division of Intramural Research, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Tiffany M. Powell-Wiley
- Social Determinants of Obesity and Cardiovascular Risk Laboratory, Cardiovascular Branch, Division of Intramural Research, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, MD, USA
- Intramural Research Program, National Institute on Minority Health and Health Disparities, National Institutes of Health, Bethesda, MD, USA
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3
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Kim N, Yi E, Kwon SJ, Park HJ, Kwon HJ, Kim HS. Filamin A Is Required for NK Cell Cytotoxicity at the Expense of Cytokine Production via Synaptic Filamentous Actin Modulation. Front Immunol 2022; 12:792334. [PMID: 35058930 PMCID: PMC8764188 DOI: 10.3389/fimmu.2021.792334] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2021] [Accepted: 12/13/2021] [Indexed: 11/23/2022] Open
Abstract
Natural killer (NK) cells are innate cytotoxic lymphocytes that efficiently eliminate malignant and virus-infected cells without prior activation via the directed and focused release of lytic granule contents for target cell lysis. This cytolytic process is tightly regulated at discrete checkpoint stages to ensure the selective killing of diseased target cells and is highly dependent on the coordinated regulation of cytoskeletal components. The actin-binding protein filamin crosslinks cortical actin filaments into orthogonal networks and links actin filament webs to cellular membranes to modulate cell migration, adhesion, and signaling. However, its role in the regulation of NK cell functions remains poorly understood. Here, we show that filamin A (FLNa), a filamin isoform with preferential expression in leukocytes, is recruited to the NK cell lytic synapse and is required for NK cell cytotoxicity through the modulation of conjugate formation with target cells, synaptic filamentous actin (F-actin) accumulation, and cytotoxic degranulation, but not granule polarization. Interestingly, we also find that the loss of FLNa augments the target cell-induced expression of IFN-γ and TNF-α by NK cells, correlating with enhanced activation signals such as Ca2+ mobilization, ERK, and NF-κB, and a delayed down-modulation of the NKG2D receptor. Thus, our results identify FLNa as a new regulator of NK cell effector functions during their decision to kill target cells through a balanced regulation of NK cell cytotoxicity vs cytokine production. Moreover, this study implicates the cross-linking/bundling of F-actin mediated by FLNa as a necessary process coordinating optimal NK effector functions.
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Affiliation(s)
- Nayoung Kim
- Department of Convergence Medicine, Asan Institute for Life Sciences, Asan Medical Center, University of Ulsan College of Medicine, Seoul, South Korea
| | - Eunbi Yi
- Department of Biomedical Sciences, Asan Medical Center, University of Ulsan College of Medicine, Seoul, South Korea
| | - Soon Jae Kwon
- Department of Biomedical Sciences, Asan Medical Center, University of Ulsan College of Medicine, Seoul, South Korea
| | - Hyo Jin Park
- Department of Biomedical Sciences, Asan Medical Center, University of Ulsan College of Medicine, Seoul, South Korea
| | - Hyung-Joon Kwon
- Department of Biomedical Sciences, Asan Medical Center, University of Ulsan College of Medicine, Seoul, South Korea
| | - Hun Sik Kim
- Stem Cell Immunomodulation Research Center (SCIRC), University of Ulsan College of Medicine, Seoul, South Korea
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4
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Bandaru S, Ala C, Zhou AX, Akyürek LM. Filamin A Regulates Cardiovascular Remodeling. Int J Mol Sci 2021; 22:ijms22126555. [PMID: 34207234 PMCID: PMC8235345 DOI: 10.3390/ijms22126555] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2021] [Revised: 06/11/2021] [Accepted: 06/15/2021] [Indexed: 01/25/2023] Open
Abstract
Filamin A (FLNA) is a large actin-binding cytoskeletal protein that is important for cell motility by stabilizing actin networks and integrating them with cell membranes. Interestingly, a C-terminal fragment of FLNA can be cleaved off by calpain to stimulate adaptive angiogenesis by transporting multiple transcription factors into the nucleus. Recently, increasing evidence suggests that FLNA participates in the pathogenesis of cardiovascular and respiratory diseases, in which the interaction of FLNA with transcription factors and/or cell signaling molecules dictate the function of vascular cells. Localized FLNA mutations associate with cardiovascular malformations in humans. A lack of FLNA in experimental animal models disrupts cell migration during embryogenesis and causes anomalies, including heart and vessels, similar to human malformations. More recently, it was shown that FLNA mediates the progression of myocardial infarction and atherosclerosis. Thus, these latest findings identify FLNA as an important novel mediator of cardiovascular development and remodeling, and thus a potential target for therapy. In this update, we summarized the literature on filamin biology with regard to cardiovascular cell function.
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Affiliation(s)
- Sashidar Bandaru
- Division of Clinical Pathology, Sahlgrenska Academy Hospital, 413 45 Gothenburg, Sweden;
- Department of Laboratory Medicine, Institute of Biomedicine, Sahlgrenska Academy, University of Gothenburg, 405 30 Gothenburg, Sweden; (C.A.); (A.-X.Z.)
| | - Chandu Ala
- Department of Laboratory Medicine, Institute of Biomedicine, Sahlgrenska Academy, University of Gothenburg, 405 30 Gothenburg, Sweden; (C.A.); (A.-X.Z.)
| | - Alex-Xianghua Zhou
- Department of Laboratory Medicine, Institute of Biomedicine, Sahlgrenska Academy, University of Gothenburg, 405 30 Gothenburg, Sweden; (C.A.); (A.-X.Z.)
| | - Levent M. Akyürek
- Division of Clinical Pathology, Sahlgrenska Academy Hospital, 413 45 Gothenburg, Sweden;
- Department of Laboratory Medicine, Institute of Biomedicine, Sahlgrenska Academy, University of Gothenburg, 405 30 Gothenburg, Sweden; (C.A.); (A.-X.Z.)
- Correspondence:
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5
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Zhou J, Kang X, An H, Lv Y, Liu X. The function and pathogenic mechanism of filamin A. Gene 2021; 784:145575. [PMID: 33737122 DOI: 10.1016/j.gene.2021.145575] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Revised: 03/04/2021] [Accepted: 03/08/2021] [Indexed: 12/13/2022]
Abstract
Filamin A(FLNa) is an actin-binding protein, which participates in the formation of the cytoskeleton, anchors a variety of proteins in the cytoskeleton and regulates cell adhesion and migration. It is involved in signal transduction, cell proliferation and differentiation, pseudopodia formation, vesicle transport, tumor resistance and genetic diseases by binding with interacting proteins. In order to fully elucidate the structure, function and pathogenesis of FLNa, we summarized all substances which directly or indirectly act on FLNa so far, upstream and downstream targets which having effect on it, signaling pathways and their functions. It also recorded the expression and effect of FLNa in different diseases, including hereditary disease and tumors.
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Affiliation(s)
- Jie Zhou
- Department of Oncology, Xiang'an Hospital of Xiamen University, School of Medicine, Xiamen University, Xiamen 361000, Fujian, China.
| | - Xinmei Kang
- Department of Oncology, Xiang'an Hospital of Xiamen University, School of Medicine, Xiamen University, Xiamen 361000, Fujian, China.
| | - Hanxiang An
- Department of Oncology, Xiang'an Hospital of Xiamen University, School of Medicine, Xiamen University, Xiamen 361000, Fujian, China.
| | - Yun Lv
- Department of Oncology, Xiang'an Hospital of Xiamen University, School of Medicine, Xiamen University, Xiamen 361000, Fujian, China.
| | - Xin Liu
- Department of Oncology, Xiang'an Hospital of Xiamen University, School of Medicine, Xiamen University, Xiamen 361000, Fujian, China.
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6
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Treppiedi D, Mangili F, Giardino E, Catalano R, Locatelli M, Lania AG, Spada A, Arosio M, Calebiro D, Mantovani G, Peverelli E. Cytoskeleton Protein Filamin A Is Required for Efficient Somatostatin Receptor Type 2 Internalization and Recycling through Rab5 and Rab4 Sorting Endosomes in Tumor Somatotroph Cells. Neuroendocrinology 2020; 110:642-652. [PMID: 31574507 DOI: 10.1159/000503791] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/10/2019] [Accepted: 09/30/2019] [Indexed: 11/19/2022]
Abstract
The high expression of somatostatin receptor 2 (SST2) in growth hormone (GH)-secreting tumors represents the rationale for the clinical use of somatostatin analogs (SSAs) in acromegaly. Recently, the cytoskeletal protein Filamin A (FLNA) has emerged as key modulator of the responsiveness of GH-secreting pituitary tumors to SSAs by regulating SST2 signaling and expression. The aim of this study was to explore FLNA involvement in SST2 intracellular trafficking in tumor somatotroph cells. By biotinylation assay, we found that FLNA silencing abolished octreotide-mediated SST2 internalization in rat GH3 cell line (28.0 ± 2.7 vs. 4 ± 4.3% SST2 internalization, control versus FLNA small interfering RNAs (siRNA) cells, respectively, p < 0.001) and human GH-secreting primary cultured cells (70.3 ± 21.1 vs. 24 ± 19.2% SST2 internalization, control versus FLNA siRNA cells, respectively, p < 0.05). In addition, confocal imaging revealed impaired SST2 recycling to the plasma membrane in FLNA silenced GH3 cells. Coimmunoprecipitation and immunofluorescence experiments showed that FLNA, as well as β-arrestin2, is timely dependent recruited to octreotide-stimulated SST2 receptors both in rat and human tumor somatotroph cells. Although FLNA expression knock down did not prevent the formation of β-arrestin2-SST2 complex in GH3 cells, it significantly impaired efficient SST2 loading into cytosolic vesicles positive for the early endocytic and recycling markers Rab5 and 4, respectively (33.7 ± 8.9% down to 25.9 ± 6.9%, p < 0.05, and 28.4 ± 7.4% down to 17.6 ± 5.7%, p < 0.01, for SST2-Rab5 and SST2-Rab4 colocalization, respectively, in control versus FLNA siRNA cells). Altogether these data support an important role for FLNA in the mediation of octreotide-induced SST2 trafficking in GH-secreting pituitary tumor cells through Rab5 and 4 sorting endosomes.
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Affiliation(s)
- Donatella Treppiedi
- Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy
| | - Federica Mangili
- Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy
| | - Elena Giardino
- Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy
| | - Rosa Catalano
- Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy
- PhD Program in Endocrinological Sciences, Sapienza University of Rome, Rome, Italy
| | - Marco Locatelli
- Department of Pathophysiology and Transplantation, University of Milan, Milan, Italy
- Neurosurgery Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Andrea Gerardo Lania
- Endocrine Unit, IRCCS Humanitas Clinical Institute, Humanitas University, Rozzano, Italy
| | - Anna Spada
- Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy
- Endocrinology Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Maura Arosio
- Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy
- Endocrinology Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Davide Calebiro
- Institute of Pharmacology and Toxicology and Bio-Imaging Center, University of Würzburg, Würzburg, Germany
- Institute of Metabolism and Systems Research, University of Birmingham, Birmingham, United Kingdom
- Centre of Membrane Proteins and Receptors, University of Birmingham, Birmingham, United Kingdom
| | - Giovanna Mantovani
- Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy,
- Endocrinology Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy,
| | - Erika Peverelli
- Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy
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7
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Treppiedi D, Jobin ML, Peverelli E, Giardino E, Sungkaworn T, Zabel U, Arosio M, Spada A, Mantovani G, Calebiro D. Single-Molecule Microscopy Reveals Dynamic FLNA Interactions Governing SSTR2 Clustering and Internalization. Endocrinology 2018; 159:2953-2965. [PMID: 29931263 DOI: 10.1210/en.2018-00368] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Accepted: 06/14/2018] [Indexed: 11/19/2022]
Abstract
The cytoskeletal protein filamin A (FLNA) has been suggested to play an important role in the responsiveness of GH-secreting pituitary tumors to somatostatin receptor subtype 2 (SSTR2) agonists by regulating SSTR2 expression and signaling. However, the underlying mechanisms are unknown. In this study, we use fast multicolor single-molecule microscopy to image individual SSTR2 and FLNA molecules at the surface of living cells with unprecedented spatiotemporal resolution. We find that SSTR2 and FLNA undergo transient interactions, which occur preferentially along actin fibers and contribute to restraining SSTR2 diffusion. Agonist stimulation increases the localization of SSTR2 along actin fibers and, subsequently, SSTR2 clustering and recruitment to clathrin-coated pits (CCPs). Interfering with FLNA-SSTR2 binding with a dominant-negative FLNA fragment increases SSTR2 mobility, hampers the formation and alignment of SSTR2 clusters along actin fibers, and impairs both SSTR2 recruitment to CCPs and SSTR2 internalization. These findings indicate that dynamic SSTR2-FLNA interactions critically control the nanoscale localization of SSTR2 at the plasma membrane and are required for coupling SSTR2 clustering to internalization. These mechanisms explain the critical role of FLNA in the control of SSTR2 expression and signaling and suggest the possibility of targeting SSTR2-FLNA interactions for the therapy of pharmacologically resistant GH-secreting pituitary tumors.
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Affiliation(s)
- Donatella Treppiedi
- Endocrinology Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
- Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy
| | - Marie-Lise Jobin
- Institute of Pharmacology and Toxicology, University of Würzburg, Würzburg, Germany
- Bio-Imaging Center/Rudolf Virchow Center, University of Würzburg, Würzburg, Germany
| | - Erika Peverelli
- Endocrinology Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
- Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy
| | - Elena Giardino
- Endocrinology Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
- Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy
| | - Titiwat Sungkaworn
- Institute of Pharmacology and Toxicology, University of Würzburg, Würzburg, Germany
- Bio-Imaging Center/Rudolf Virchow Center, University of Würzburg, Würzburg, Germany
| | - Ulrike Zabel
- Institute of Pharmacology and Toxicology, University of Würzburg, Würzburg, Germany
- Bio-Imaging Center/Rudolf Virchow Center, University of Würzburg, Würzburg, Germany
| | - Maura Arosio
- Endocrinology Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
- Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy
| | - Anna Spada
- Endocrinology Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
- Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy
| | - Giovanna Mantovani
- Endocrinology Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
- Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy
| | - Davide Calebiro
- Institute of Pharmacology and Toxicology, University of Würzburg, Würzburg, Germany
- Bio-Imaging Center/Rudolf Virchow Center, University of Würzburg, Würzburg, Germany
- Institute of Metabolism and Systems Research, University of Birmingham, Birmingham, United Kingdom
- Centre of Membrane Proteins and Receptors (COMPARE), Universities of Birmingham and Nottingham, Birmingham, United Kingdom
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Treppiedi D, Peverelli E, Giardino E, Ferrante E, Calebiro D, Spada A, Mantovani G. Somatostatin Receptor Type 2 (SSTR2) Internalization and Intracellular Trafficking in Pituitary GH-Secreting Adenomas: Role of Scaffold Proteins and Implications for Pharmacological Resistance. Horm Metab Res 2017; 49:259-268. [PMID: 27632151 DOI: 10.1055/s-0042-116025] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
AbstractSomatostatin receptor type 2 (SSTR2), together with SSTR5, represents the main
target of medical treatment for growth hormone (GH)-secreting pituitary tumors,
since it is expressed in most of these tumors and exerts both antiproliferative
and cytostatic effects, and reduces hormone secretion, as well. However,
clinical practice indicates a great variability in the frequency and entity of
favorable responses of acromegalic patients to long-acting somatostatin
analogues (SSAs), but the molecular mechanisms regulating this pharmacological
resistance are not completely understood. So far, several potentially implied
mechanisms have been suggested, including impaired expression of SSTRs, or
post-receptor signal transduction alterations. More recently, new studies
exploited the molecular factors involved in SSTRs intracellular trafficking
regulation, this being a critical point for the modulation of the available
active G-coupled receptors (GPCRs) amount at the cell surface. In this respect,
the role of the scaffold proteins such as β-arrestins, and the cytoskeleton
protein Filamin A (FLNA), have become of relevant importance for GH-secreting
pituitary tumors. In fact, β-arrestins are linked to SSTR2 desensitization and
internalization, and FLNA is able to regulate SSTR2 trafficking and stability at
the plasma membrane. Therefore, the present review will summarize emerging
evidence highlighting the role of β-arrestins and FLNA, as possible novel
players in the modulation of agonist activated-SSTR2 receptor trafficking and
response in GH-secreting pituitary tumors.
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Affiliation(s)
- D Treppiedi
- Endocrine Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico; Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy
| | - E Peverelli
- Endocrine Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico; Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy
| | - E Giardino
- Endocrine Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico; Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy
| | - E Ferrante
- Endocrine Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico; Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy
| | - D Calebiro
- Institute of Pharmacology and Toxicology, University of Würzburg, and Rudolf Virchow Center, Bio-Imaging Center, Würzburg, Germany
| | - A Spada
- Endocrine Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico; Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy
| | - G Mantovani
- Endocrine Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico; Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy
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9
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Neethling A, Mouton J, Loos B, Corfield V, de Villiers C, Kinnear C. Filamin C: a novel component of the KCNE2 interactome during hypoxia. Cardiovasc J Afr 2016; 27:4-11. [PMID: 26956495 PMCID: PMC4816932 DOI: 10.5830/cvja-2015-049] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2014] [Accepted: 05/17/2015] [Indexed: 12/16/2022] Open
Abstract
Aim KCNE2 encodes for the potassium voltage-gated channel, KCNE2. Mutations in KCNE2 have been associated with long-QT syndrome (LQTS). While KCNE2 has been extensively studied, the functions of its C-terminal domain remain inadequately described. Here, we aimed to elucidate the functions of this domain by identifying its protein interactors using yeast two-hybrid analysis. Methods The C-terminal domain of KCNE2 was used as bait to screen a human cardiac cDNA library for putative interacting proteins. Co-localisation and co-immunoprecipitation analyses were used for verification. Results Filamin C (FLNC) was identified as a putative interactor with KCNE2. FLNC and KCNE2 co-localised within the cell, however, a physical interaction was only observed under hypoxic conditions. Conclusion The identification of FLNC as a novel KCNE2 ligand not only enhances current understanding of ion channel function and regulation, but also provides valuable information about possible pathways likely to be involved in LQTS pathogenesis.
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Affiliation(s)
- Annika Neethling
- DST/NRF Centre of Excellence in Biomedical Tuberculosis Research, SA MRC Centre for Tuberculosis Research, Division of Molecular Biology and Human Genetics, Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Stellenbosch University, South Africa
| | - Jomien Mouton
- DST/NRF Centre of Excellence in Biomedical Tuberculosis Research, SA MRC Centre for Tuberculosis Research, Division of Molecular Biology and Human Genetics, Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Stellenbosch University, South Africa
| | - Ben Loos
- Department of Physiological Sciences, Faculty of Science, Stellenbosch University, Stellenbosch, South Africa
| | - Valerie Corfield
- DST/NRF Centre of Excellence in Biomedical Tuberculosis Research, SA MRC Centre for Tuberculosis Research, Division of Molecular Biology and Human Genetics, Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Stellenbosch University, South Africa
| | - Carin de Villiers
- DST/NRF Centre of Excellence in Biomedical Tuberculosis Research, SA MRC Centre for Tuberculosis Research, Division of Molecular Biology and Human Genetics, Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Stellenbosch University, South Africa
| | - Craig Kinnear
- DST/NRF Centre of Excellence in Biomedical Tuberculosis Research, SA MRC Centre for Tuberculosis Research, Division of Molecular Biology and Human Genetics, Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Stellenbosch University, South Africa
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Zhang Z, Ledford HA, Park S, Wang W, Rafizadeh S, Kim HJ, Xu W, Lu L, Lau VC, Knowlton AA, Zhang XD, Yamoah EN, Chiamvimonvat N. Distinct subcellular mechanisms for the enhancement of the surface membrane expression of SK2 channel by its interacting proteins, α-actinin2 and filamin A. J Physiol 2016; 595:2271-2284. [PMID: 27779751 PMCID: PMC5374114 DOI: 10.1113/jp272942] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Accepted: 10/19/2016] [Indexed: 12/16/2022] Open
Abstract
KEY POINTS Ion channels are transmembrane proteins that are synthesized within the cells but need to be trafficked to the cell membrane for the channels to function. Small-conductance, Ca2+ -activated K+ channels (SK, KCa 2) are unique subclasses of K+ channels that are regulated by Ca2+ inside the cells; they are expressed in human atrial myocytes and responsible for shaping atrial action potentials. We have previously shown that interacting proteins of SK2 channels are important for channel trafficking to the membrane. Using total internal reflection fluorescence (TIRF) and confocal microscopy, we studied the mechanisms by which the surface membrane localization of SK2 (KCa 2.2) channels is regulated by their interacting proteins. Understanding the mechanisms of SK channel trafficking may provide new insights into the regulation controlling the repolarization of atrial myocytes. ABSTRACT The normal function of ion channels depends critically on the precise subcellular localization and the number of channel proteins on the cell surface membrane. Small-conductance, Ca2+ -activated K+ channels (SK, KCa 2) are expressed in human atrial myocytes and are responsible for shaping atrial action potentials. Understanding the mechanisms of SK channel trafficking may provide new insights into the regulation controlling the repolarization of atrial myocytes. We have previously demonstrated that the C- and N-termini of SK2 channels interact with the actin-binding proteins α-actinin2 and filamin A, respectively. However, the roles of the interacting proteins on SK2 channel trafficking remain incompletely understood. Using total internal reflection fluorescence (TIRF) microscopy, we studied the mechanisms of surface membrane localization of SK2 (KCa 2.2) channels. When SK2 channels were co-expressed with filamin A or α-actinin2, the membrane fluorescence intensity of SK2 channels increased significantly. We next tested the effects of primaquine and dynasore on SK2 channels expression. Treatment with primaquine significantly reduced the membrane expression of SK2 channels. In contrast, treatment with dynasore failed to alter the surface membrane expression of SK2 channels. Further investigations using constitutively active or dominant-negative forms of Rab GTPases provided additional insights into the distinct roles of the two cytoskeletal proteins on the recycling processes of SK2 channels from endosomes. α-Actinin2 facilitated recycling of SK2 channels from both early and recycling endosomes while filamin A probably aids the recycling of SK2 channels from recycling endosomes.
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Affiliation(s)
- Zheng Zhang
- Division of Cardiovascular Medicine, Department of Internal Medicine, University of California, Davis, CA, 95616, USA
| | - Hannah A Ledford
- Division of Cardiovascular Medicine, Department of Internal Medicine, University of California, Davis, CA, 95616, USA
| | - Seojin Park
- Division of Cardiovascular Medicine, Department of Internal Medicine, University of California, Davis, CA, 95616, USA
| | - Wenying Wang
- Department of Physiology and Cell Biology, University of Nevada, Reno, NV, 89557, USA
| | - Sassan Rafizadeh
- Division of Cardiovascular Medicine, Department of Internal Medicine, University of California, Davis, CA, 95616, USA
| | - Hyo Jeong Kim
- Division of Cardiovascular Medicine, Department of Internal Medicine, University of California, Davis, CA, 95616, USA
| | - Wilson Xu
- Division of Cardiovascular Medicine, Department of Internal Medicine, University of California, Davis, CA, 95616, USA
| | - Ling Lu
- Division of Cardiovascular Medicine, Department of Internal Medicine, University of California, Davis, CA, 95616, USA.,Jiangsu Key Laboratory for Microbes and Functional Genomics, Jiangsu Engineering and Technology Research Center for Microbiology, College of Life Sciences, Nanjing Normal University, Nanjing, 210046, China
| | - Victor C Lau
- Division of Cardiovascular Medicine, Department of Internal Medicine, University of California, Davis, CA, 95616, USA
| | - Anne A Knowlton
- Division of Cardiovascular Medicine, Department of Internal Medicine, University of California, Davis, CA, 95616, USA.,Department of Veterans Affairs, Northern California Health Care System, Mather, CA, 95655, USA
| | - Xiao-Dong Zhang
- Division of Cardiovascular Medicine, Department of Internal Medicine, University of California, Davis, CA, 95616, USA
| | - Ebenezer N Yamoah
- Department of Physiology and Cell Biology, University of Nevada, Reno, NV, 89557, USA
| | - Nipavan Chiamvimonvat
- Division of Cardiovascular Medicine, Department of Internal Medicine, University of California, Davis, CA, 95616, USA.,Department of Veterans Affairs, Northern California Health Care System, Mather, CA, 95655, USA
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11
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Lacalle RA, Blanco R, Carmona-Rodríguez L, Martín-Leal A, Mira E, Mañes S. Chemokine Receptor Signaling and the Hallmarks of Cancer. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2016; 331:181-244. [PMID: 28325212 DOI: 10.1016/bs.ircmb.2016.09.011] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The chemokines are a family of chemotactic cytokines that mediate their activity by acting on seven-transmembrane-spanning G protein-coupled receptors. Both the ability of the chemokines and their receptors to form homo- and heterodimers and the promiscuity of the chemokine-chemokine receptor interaction endow this protein family with enormous signaling plasticity and complexity that are not fully understood at present. Chemokines were initially identified as essential regulators of homeostatic and inflammatory trafficking of innate and adaptive leucocytes from lymphoid organs to tissues. Chemokines also mediate the host response to cancer. Nevertheless, chemokine function in this response is not limited to regulating leucocyte infiltration into the tumor microenvironment. It is now known that chemokines and their receptors influence most-if not all-hallmark processes of cancer; they act on both neoplastic and untransformed cells in the tumor microenvironment, including fibroblasts, endothelial cells (blood and lymphatic), bone marrow-derived stem cells, and, obviously, infiltrating leucocytes. This review begins with an overview of chemokine and chemokine receptor structure, to better define how chemokines affect the proliferation, survival, stemness, and metastatic potential of neoplastic cells. We also examine the main mechanisms by which chemokines regulate tumor angiogenesis and immune cell infiltration, emphasizing the pro- and antitumorigenic activity of this protein superfamily in these interrelated processes.
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Affiliation(s)
- R A Lacalle
- Centro Nacional de Biotecnología/CSIC, Madrid, Spain
| | - R Blanco
- Centro Nacional de Biotecnología/CSIC, Madrid, Spain
| | | | - A Martín-Leal
- Centro Nacional de Biotecnología/CSIC, Madrid, Spain
| | - E Mira
- Centro Nacional de Biotecnología/CSIC, Madrid, Spain
| | - S Mañes
- Centro Nacional de Biotecnología/CSIC, Madrid, Spain.
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12
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Pons M, Izquierdo I, Andreu-Carbó M, Garrido G, Planagumà J, Muriel O, Geli MI, Aragay AM. Regulation of chemokine receptor CCR2 recycling by filamin a phosphorylation. J Cell Sci 2016; 130:490-501. [DOI: 10.1242/jcs.193821] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Accepted: 11/18/2016] [Indexed: 12/20/2022] Open
Abstract
Proper endosomal trafficking of ligand-activated G protein-coupled receptors (GPCRs) is essential to spatiotemporally tune their physiological responses. For the monocyte chemoattractant receptor 2 (CCR2B), endocytic recycling is important to sustain monocyte migration; while filamin A (FLNa) is essential for CCL2-induced monocyte migration. Here, we analyze the role of FLNa in the trafficking of CCR2B along the endocytic pathway. In FLNa knockdown cells, activated CCR2B accumulated in enlarged EEA-1-positive endosomes, which exhibited slow movement and fast fluorescence recovery, suggesting an imbalance between receptor entry and exit rates. Utilizing super-resolution microscopy, we observed that FLNa-GFP, CCR2B and β2-adrenergic receptor (β2AR) were present in actin-enriched endosomal microdomains. Depletion of FLNa decreased CCR2B association with these microdomains and concomitantly delayed CCR2B endosomal traffic, without apparently affecting the number of microdomains. Interestingly, CCR2B and β2AR signaling induced phosphorylation of FLNa at S2152 and this phosphorylation event was contributes to sustain receptor recycling. Thus, our data strongly suggest that CCR2B and β2AR signals to FLNa to stimulate its endocytosis and recycling to the plasma membrane.
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Affiliation(s)
- Mònica Pons
- Molecular Biology Institute of Barcelona (IBMB), Spanish National Research Council (CSIC), 08028 Barcelona, Spain
| | - Ismael Izquierdo
- Molecular Biology Institute of Barcelona (IBMB), Spanish National Research Council (CSIC), 08028 Barcelona, Spain
| | - Mireia Andreu-Carbó
- Molecular Biology Institute of Barcelona (IBMB), Spanish National Research Council (CSIC), 08028 Barcelona, Spain
| | - Georgina Garrido
- Molecular Biology Institute of Barcelona (IBMB), Spanish National Research Council (CSIC), 08028 Barcelona, Spain
- Present addresse: Centre for Genomic Regulation (CRG), 08003 Barcelona, Spain
| | - Jesús Planagumà
- Department of Biomedicine, University of Bergen, Bergen, Norway
- Present addresse: Department of Neuroimmunology, IDIBAPS, Barcelona, Spain
| | - Olivia Muriel
- Centro Nacional de Investigaciones Cardiovasculares, 28029 Madrid, Spain
| | - M. Isabel Geli
- Molecular Biology Institute of Barcelona (IBMB), Spanish National Research Council (CSIC), 08028 Barcelona, Spain
| | - Anna M. Aragay
- Molecular Biology Institute of Barcelona (IBMB), Spanish National Research Council (CSIC), 08028 Barcelona, Spain
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13
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Tirupula KC, Ithychanda SS, Mohan ML, Naga Prasad SV, Qin J, Karnik SS. G protein-coupled receptors directly bind filamin A with high affinity and promote filamin phosphorylation. Biochemistry 2015; 54:6673-83. [PMID: 26460884 PMCID: PMC4642222 DOI: 10.1021/acs.biochem.5b00975] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Although interaction of a few G protein-coupled receptors (GPCRs) with Filamin A, a key actin cross-linking and biomechanical signal transducer protein, has been observed, a comprehensive structure-function analysis of this interaction is lacking. Through a systematic sequence-based analysis, we found that a conserved filamin binding motif is present in the cytoplasmic domains of >20% of the 824 GPCRs encoded in the human genome. Direct high-affinity interaction of filamin binding motif peptides of select GPCRs with the Ig domain of Filamin A was confirmed by nuclear magnetic resonance spectroscopy and isothermal titration calorimetric experiments. Engagement of the filamin binding motif with the Filamin A Ig domain induced the phosphorylation of filamin by protein kinase A in vitro. In transfected cells, agonist activation as well as constitutive activation of representative GPCRs dramatically elicited recruitment and phosphorylation of cellular Filamin A, a phenomenon long known to be crucial for regulating the structure and dynamics of the cytoskeleton. Our data suggest a molecular mechanism for direct GPCR-cytoskeleton coupling via filamin. Until now, GPCR signaling to the cytoskeleton was predominantly thought to be indirect, through canonical G protein-mediated signaling cascades involving GTPases, adenylyl cyclases, phospholipases, ion channels, and protein kinases. We propose that the GPCR-induced filamin phosphorylation pathway is a conserved, novel biochemical signaling paradigm.
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Affiliation(s)
- Kalyan C Tirupula
- Department of Molecular Cardiology, Lerner Research Institute, Cleveland Clinic , Cleveland, Ohio 44195, United States
| | - Sujay S Ithychanda
- Department of Molecular Cardiology, Lerner Research Institute, Cleveland Clinic , Cleveland, Ohio 44195, United States
| | - Maradumane L Mohan
- Department of Molecular Cardiology, Lerner Research Institute, Cleveland Clinic , Cleveland, Ohio 44195, United States
| | - Sathyamangla V Naga Prasad
- Department of Molecular Cardiology, Lerner Research Institute, Cleveland Clinic , Cleveland, Ohio 44195, United States
| | - Jun Qin
- Department of Molecular Cardiology, Lerner Research Institute, Cleveland Clinic , Cleveland, Ohio 44195, United States
| | - Sadashiva S Karnik
- Department of Molecular Cardiology, Lerner Research Institute, Cleveland Clinic , Cleveland, Ohio 44195, United States
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van der Werf CS, Halim D, Verheij JB, Alves MM, Hofstra RM. Congenital Short Bowel Syndrome: from clinical and genetic diagnosis to the molecular mechanisms involved in intestinal elongation. Biochim Biophys Acta Mol Basis Dis 2015; 1852:2352-61. [DOI: 10.1016/j.bbadis.2015.08.007] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2015] [Revised: 08/11/2015] [Accepted: 08/12/2015] [Indexed: 12/16/2022]
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15
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Filamin A interaction with the CXCR4 third intracellular loop regulates endocytosis and signaling of WT and WHIM-like receptors. Blood 2014; 125:1116-25. [PMID: 25355818 DOI: 10.1182/blood-2014-09-601807] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Warts, hypogammaglobulinemia, infections, and myelokathexis (WHIM) syndrome is a rare congenital immunodeficiency often caused by mutations in the last 10 to 19 C-terminal amino acids of CXCR4. These mutations impair CXCR4 internalization and increase responsiveness to CXCL12. The CXCR4 C-terminal domain (C-tail) also has a binding site for the actin-binding protein filamin A (FLNA); it is not known whether FLNA binds to WHIM CXCR4 mutants or whether this interaction is implicated in the hyperfunction of these receptors. Here we show that, in addition to interacting with the CXCR4 C-tail, FLNA interacted with a region in the receptor third intracellular loop (ICL3) spanning amino acids 238 to 246. This interaction involved specific FLNA repeats and was sensitive to Rho kinase inhibition. Deletion of the 238-246 motif accelerated CXCL12-induced wild-type (WT) receptor endocytosis but enabled CXCL12-mediated endocytosis and normalized signaling by the WHIM-associated receptor CXCR4(R334X). CXCL12 stimulation triggered CXCR4(R334X) internalization in FLNA-deficient M2 cells but not in the FLNA-expressing M2 subclone A7; this suggests a role for FLNA in stabilization of WHIM-like CXCR4 at the cell surface. FLNA increased β-arrestin2 binding to CXCR4(R334X) in vivo, which provides a molecular basis for FLNA-mediated hyperactivation of WHIM receptor signaling. We propose that FLNA interaction with ICL3 is central for endocytosis and signaling of WT and WHIM-like CXCR4 receptors.
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16
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Functional interaction with filamin A and intracellular Ca2+ enhance the surface membrane expression of a small-conductance Ca2+-activated K+ (SK2) channel. Proc Natl Acad Sci U S A 2014; 111:9989-94. [PMID: 24951510 DOI: 10.1073/pnas.1323541111] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
For an excitable cell to function properly, a precise number of ion channel proteins need to be trafficked to distinct locations on the cell surface membrane, through a network and anchoring activity of cytoskeletal proteins. Not surprisingly, mutations in anchoring proteins have profound effects on membrane excitability. Ca(2+)-activated K(+) channels (KCa2 or SK) have been shown to play critical roles in shaping the cardiac atrial action potential profile. Here, we demonstrate that filamin A, a cytoskeletal protein, augments the trafficking of SK2 channels in cardiac myocytes. The trafficking of SK2 channel is Ca(2+)-dependent. Further, the Ca(2+) dependence relies on another channel-interacting protein, α-actinin2, revealing a tight, yet intriguing, assembly of cytoskeletal proteins that orchestrate membrane expression of SK2 channels in cardiac myocytes. We assert that changes in SK channel trafficking would significantly alter atrial action potential and consequently atrial excitability. Identification of therapeutic targets to manipulate the subcellular localization of SK channels is likely to be clinically efficacious. The findings here may transcend the area of SK2 channel studies and may have implications not only in cardiac myocytes but in other types of excitable cells.
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17
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Noam Y, Ehrengruber MU, Koh A, Feyen P, Manders EMM, Abbott GW, Wadman WJ, Baram TZ. Filamin A promotes dynamin-dependent internalization of hyperpolarization-activated cyclic nucleotide-gated type 1 (HCN1) channels and restricts Ih in hippocampal neurons. J Biol Chem 2014; 289:5889-903. [PMID: 24403084 PMCID: PMC3937658 DOI: 10.1074/jbc.m113.522060] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2013] [Revised: 12/27/2013] [Indexed: 11/06/2022] Open
Abstract
The actin-binding protein filamin A (FLNa) regulates neuronal migration during development, yet its roles in the mature brain remain largely obscure. Here, we probed the effects of FLNa on the regulation of ion channels that influence neuronal properties. We focused on the HCN1 channels that conduct Ih, a hyperpolarization-activated current crucial for shaping intrinsic neuronal properties. Whereas regulation of HCN1 channels by FLNa has been observed in melanoma cell lines, its physiological relevance to neuronal function and the underlying cellular pathways that govern this regulation remain unknown. Using a combination of mutational, pharmacological, and imaging approaches, we find here that FLNa facilitates a selective and reversible dynamin-dependent internalization of HCN1 channels in HEK293 cells. This internalization is accompanied by a redistribution of HCN1 channels on the cell surface, by accumulation of the channels in endosomal compartments, and by reduced Ih density. In hippocampal neurons, expression of a truncated dominant-negative FLNa enhances the expression of native HCN1. Furthermore, acute abrogation of HCN1-FLNa interaction in neurons, with the use of decoy peptides that mimic the FLNa-binding domain of HCN1, abolishes the punctate distribution of HCN1 channels in neuronal cell bodies, augments endogenous Ih, and enhances the rebound-response ("voltage-sag") of the neuronal membrane to transient hyperpolarizing events. Together, these results support a major function of FLNa in modulating ion channel abundance and membrane trafficking in neurons, thereby shaping their biophysical properties and function.
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Affiliation(s)
- Yoav Noam
- From the Departments of Anatomy/Neurobiology and Pediatrics and
| | | | - Annie Koh
- From the Departments of Anatomy/Neurobiology and Pediatrics and
| | | | - Erik M. M. Manders
- van Leeuwenhoek Centre for Advanced Microscopy, University of Amsterdam, 1098XH Amsterdam, The Netherlands
| | - Geoffrey W. Abbott
- Pharmacology, University of California at Irvine, Irvine, California 92697-4475 and
| | | | - Tallie Z. Baram
- From the Departments of Anatomy/Neurobiology and Pediatrics and
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CBAP functions as a novel component in chemokine-induced ZAP70-mediated T-cell adhesion and migration. PLoS One 2013; 8:e61761. [PMID: 23620790 PMCID: PMC3631140 DOI: 10.1371/journal.pone.0061761] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2013] [Accepted: 03/11/2013] [Indexed: 01/22/2023] Open
Abstract
Activated chemokine receptor initiates inside-out signaling to transiently trigger activation of integrins, a process involving multiple components that have not been fully characterized. Here we report that GM-CSF/IL-3/IL-5 receptor common beta-chain-associated protein (CBAP) is required to optimize this inside-out signaling and activation of integrins. First, knockdown of CBAP expression in human Jurkat T cells caused attenuated CXC chemokine ligand-12 (CXCL12)-induced cell migration and integrin α4β1- and αLβ2-mediated cell adhesion in vitro, which could be rescued sufficiently upon expression of murine CBAP proteins. Freshly isolated CBAP-deficient primary T cells also exhibited diminution of chemotaxis toward CC chemokine ligand-21 (CCL21) and CXCL12, and these chemokines-induced T-cell adhesions in vitro. Adoptive transfer of isolated naive T cells demonstrated that CBAP deficiency significantly reduced lymph node homing ability in vivo. Finally, migration of T cell-receptor-activated T cells induced by inflammatory chemokines was also attenuated in CBAP-deficient cells. Further analyses revealed that CBAP constitutively associated with both integrin β1 and ZAP70 and that CBAP is required for chemokine-induced initial binding of the talin-Vav1 complex to integrin β1 and to facilitate subsequent ZAP70-mediated dissociation of the talin-Vav1 complex and Vav1 phosphorylation. Within such an integrin signaling complex, CBAP likely functions as an adaptor and ultimately leads to activation of both integrin α4β1 and Rac1. Taken together, our data suggest that CBAP indeed can function as a novel signaling component within the ZAP70/Vav1/talin complex and plays an important role in regulating chemokine-promoted T-cell trafficking.
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Abstract
β-Arrestins regulate G protein-coupled receptors through receptor desensitization while also acting as signaling scaffolds to facilitate numerous effector pathways. Recent studies have provided evidence that β-arrestins play a key role in inflammatory responses. Here, we summarize these advances on the roles of β-arrestins in immune regulation and inflammatory responses under physiological and pathological conditions, with an emphasis on translational implications of β-arrestins on human diseases.
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20
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Planagumà J, Minsaas L, Pons M, Myhren L, Garrido G, Aragay AM. Filamin A-hinge region 1-EGFP: a novel tool for tracking the cellular functions of filamin A in real-time. PLoS One 2012; 7:e40864. [PMID: 22870205 PMCID: PMC3411599 DOI: 10.1371/journal.pone.0040864] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2010] [Accepted: 06/18/2012] [Indexed: 01/13/2023] Open
Abstract
Background Filamin A (FLNa) is an actin-crosslinking protein necessary for stabilizing the cell surface, organizing protrusive activity and for promoting efficient cellular translocation. Recently, our group demonstrated the requirement of FLNa for the internalization of the chemokine receptor CCR2B. Methodology and Principal Findings In order to study the role of FLNa in vitro and in real-time, we have developed a fluorescent FLNa-EGFP construct. In this novel imaging tool, we introduced the EGFP-tag inside the flexible hinge 1 region of FLNa between two calpain cleavage sites. Our findings indicate that the FLNa-EGFP construct was correctly expressed, cleaved by calpain and colocalized with actin filaments as shown by immunostaining experiments in the human melanoma cell lines A7 (FLNa-repleted) and M2 (FLNa-deficient). In addition, scanning-electron microscopy (SEM) and micropatterning studies also provided clear evidence that the cell rigidity was restored. FLNa-EGFP allowed us to demonstrate the interaction of FLNa with the chemokine receptor CCR2B in endocytic vesicles after CCL2 ligand stimulation. Through live-cell imaging studies we show that the CCR2B receptor in Rab5-positive vesicles moves along filamin A-positive fibers. Significance Taken together, these results outline the functionality of the FLNa-EGFP and the importance of filamin A for receptor internalization and movement into endocytic vesicles.
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Affiliation(s)
- Jesús Planagumà
- Department of Biomedicine, University of Bergen, Bergen, Norway
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Bennett LD, Fox JM, Signoret N. Mechanisms regulating chemokine receptor activity. Immunology 2011; 134:246-56. [PMID: 21977995 PMCID: PMC3209565 DOI: 10.1111/j.1365-2567.2011.03485.x] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2011] [Revised: 07/04/2011] [Accepted: 07/12/2011] [Indexed: 12/21/2022] Open
Abstract
Co-ordinated movement and controlled positioning of leucocytes is key to the development, maintenance and proper functioning of the immune system. Chemokines and their receptors play an essential role in these events by mediating directed cell migration, often referred to as chemotaxis. The chemotactic property of these molecules is also thought to contribute to an array of pathologies where inappropriate recruitment of specific chemokine receptor-expressing leucocytes is observed, including cancer and inflammatory diseases. As a result, chemokine receptors have become major targets for therapeutic intervention, and during the past 15 years much research has been devoted to understanding the regulation of their biological activity. From these studies, processes which govern the availability of functional chemokine receptors at the cell surface have emerged as playing a central role. In this review, we summarize and discuss current knowledge on the molecular mechanisms contributing to the regulation of chemokine receptor surface expression, from gene transcription and protein degradation to post-translational modifications, multimerization, intracellular transport and cross-talk.
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Affiliation(s)
- Laura D Bennett
- Centre for Immunology and Infection, Department of Biology and Hull York Medical School, University of York, York, UK
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Matsushima K, Terashima Y, Toda E, Shand F, Ueha S. Chemokines in inflammatory and immune diseases. Inflamm Regen 2011. [DOI: 10.2492/inflammregen.31.11] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
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