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Steenkiste EM, Berndt JD, Pilling C, Simpkins C, Cooper JA. A Cas-BCAR3 co-regulatory circuit controls lamellipodia dynamics. eLife 2021; 10:67078. [PMID: 34169835 PMCID: PMC8266394 DOI: 10.7554/elife.67078] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2021] [Accepted: 06/21/2021] [Indexed: 11/13/2022] Open
Abstract
Integrin adhesion complexes regulate cytoskeletal dynamics during cell migration. Adhesion activates phosphorylation of integrin-associated signaling proteins, including Cas (p130Cas, BCAR1), by Src-family kinases. Cas regulates leading-edge protrusion and migration in cooperation with its binding partner, BCAR3. However, it has been unclear how Cas and BCAR3 cooperate. Here, using normal epithelial cells, we find that BCAR3 localization to integrin adhesions requires Cas. In return, Cas phosphorylation, as well as lamellipodia dynamics and cell migration, requires BCAR3. These functions require the BCAR3 SH2 domain and a specific phosphorylation site, Tyr 117, that is also required for BCAR3 downregulation by the ubiquitin-proteasome system. These findings place BCAR3 in a co-regulatory positive-feedback circuit with Cas, with BCAR3 requiring Cas for localization and Cas requiring BCAR3 for activation and downstream signaling. The use of a single phosphorylation site in BCAR3 for activation and degradation ensures reliable negative feedback by the ubiquitin-proteasome system.
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Affiliation(s)
- Elizabeth M Steenkiste
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, United States.,Molecular and Cellular Biology Program, University of Washington, Seattle, United States
| | - Jason D Berndt
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, United States
| | - Carissa Pilling
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, United States.,Molecular and Cellular Biology Program, University of Washington, Seattle, United States
| | - Christopher Simpkins
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, United States
| | - Jonathan A Cooper
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, United States.,Molecular and Cellular Biology Program, University of Washington, Seattle, United States
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2
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ProNGF increases breast tumor aggressiveness through functional association of TrkA with EphA2. Cancer Lett 2019; 449:196-206. [PMID: 30771434 DOI: 10.1016/j.canlet.2019.02.019] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2018] [Revised: 02/07/2019] [Accepted: 02/10/2019] [Indexed: 12/19/2022]
Abstract
ProNGF expression has been linked to several types of cancers including breast cancer, and we have previously shown that proNGF stimulates breast cancer invasion in an autocrine manner through membrane receptors sortilin and TrkA. However, little is known regarding TrkA-associated protein partners upon proNGF stimulation. By proteomic analysis and proximity ligation assays, we found that proNGF binding to sortilin induced sequential formation of the functional sortilin/TrkA/EphA2 complex, leading to TrkA-phosphorylation dependent Akt activation and EphA2-dependent Src activation. EphA2 inhibition using siRNA approach abolished proNGF-stimulated clonogenic growth of breast cancer cell lines. Combinatorial targeting of TrkA and EphA2 dramatically reduced colony formation in vitro, primary tumor growth and metastatic dissemination towards the brain in vivo. Finally, proximity ligation assay in breast tumor samples revealed that increased TrkA/EphA2 proximity ligation assay signals were correlated with a decrease of overall survival in patients. All together, these data point out the importance of TrkA/EphA2 functional association in proNGF-induced tumor promoting effects, and provide a rationale to target proNGF/TrkA/EphA2 axis by alternative methods other than the simple use of tyrosine kinase inhibitors in breast cancer.
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3
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Gomi F, Uchida Y, Endo S. Up-regulation of NSP3 by Oligomeric Aβ Accelerates Neuronal Death Through Cas-independent Rap1A Activation. Neuroscience 2018; 386:182-193. [PMID: 29966723 DOI: 10.1016/j.neuroscience.2018.06.035] [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: 10/25/2017] [Revised: 06/20/2018] [Accepted: 06/21/2018] [Indexed: 11/17/2022]
Abstract
β-Amyloid (Aβ) plays an important role in the early pathogenesis of Alzheimer's disease (AD). In vitro studies have demonstrated that Aβ oligomers induce hippocampal and neocortical neuronal death. However the neurotoxic mechanisms by which soluble Aβ oligomers cause neuronal damage and death remain to be fully elucidated. To this end, we analyzed the gene expression profile of rat cerebral cortical neurons treated with Aβ oligomers in vitro. Aβ treatment induced the expression of novel SH2-containing protein 3 (NSP3), an adaptor molecule interacting with Cas family proteins. NSP3 expression was upregulated not only in oligomeric-Aβ-treated cultured neurons but also in the neocortex of aged Tg2576 mice. NSP3 overexpression in cultured cortical neurons accelerated neuronal death. The C-terminal region of NSP3 unbound to a Cas protein was necessary for the NSP3-induced acceleration of neuronal death, as was Cas-independent Rap1A activation downstream of NSP3. Moreover, NSP3 RNAi knockdown partially rescued Aβ-oligomer-treated neurons. These results indicate that NSP3 upregulation by soluble Aβ oligomers may accelerate neuronal death via Cas-independent Rap1A activation, implicating NSP3 in the pathogenesis of AD.
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Affiliation(s)
- Fujiya Gomi
- Tokyo Metropolitan Institute of Gerontology, 35-2 Sakaecho, Itabashi-ku, Tokyo 173-0015, Japan.
| | - Yoko Uchida
- Tokyo Metropolitan Institute of Gerontology, 35-2 Sakaecho, Itabashi-ku, Tokyo 173-0015, Japan
| | - Shogo Endo
- Tokyo Metropolitan Institute of Gerontology, 35-2 Sakaecho, Itabashi-ku, Tokyo 173-0015, Japan.
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4
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Herbin O, Regelmann AG, Ramkhelawon B, Weinstein EG, Moore KJ, Alexandropoulos K. Monocyte Adhesion and Plaque Recruitment During Atherosclerosis Development Is Regulated by the Adapter Protein Chat-H/SHEP1. Arterioscler Thromb Vasc Biol 2016; 36:1791-801. [PMID: 27417580 PMCID: PMC5001917 DOI: 10.1161/atvbaha.116.308014] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Accepted: 07/04/2016] [Indexed: 01/01/2023]
Abstract
OBJECTIVE The chronic inflammation associated with atherosclerosis is caused by lipid deposition followed by leukocyte recruitment to the arterial wall. We previously showed that the hematopoietic cell-specific adaptor protein Cas- and Hef1-associated signal transducer hematopoietic isoform (Chat-H)/SHEP1 regulated lymphocyte adhesion and migration. In this study, we analyzed the role of Chat-H in atherosclerosis development. APPROACH AND RESULTS Using Chat-H-deficient bone marrow transplantation in low-density lipoprotein receptor-deficient mice, we found that Chat-H regulated atherosclerotic plaque formation. Chat-H deficiency in hematopoietic cells associated with lower plaque complexity and fewer leukocytes in the lesions, whereas myeloid-specific deletion of Chat-H was sufficient for conferring atheroprotection. Chat-H deficiency resulted in reduced recruitment of classical Ly6c(high) and nonclassical Ly6c(low) monocytes to the plaques, which was accompanied by increased numbers of both monocyte subsets in the blood. This associated with defective adhesion of Chat-H-deficient Ly6c(high) and Ly6c(low) monocytes to vascular cell adhesion molecule-1 in vitro and impaired infiltration of fluorescent bead-loaded monocytes to atherosclerotic plaques. In contrast, Chat-H was dispensable for CX3CL1 and CCR1/CCR5-dependent migration of monocytes. CONCLUSIONS Our findings highlight Chat-H as a key protein that regulates atherosclerosis development by controlling monocyte adhesion and recruitment to the plaques and identify a novel target that may be exploited for treating atherosclerosis.
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MESH Headings
- Adaptor Proteins, Signal Transducing/deficiency
- Adaptor Proteins, Signal Transducing/genetics
- Adaptor Proteins, Signal Transducing/metabolism
- Animals
- Antigens, Ly/metabolism
- Atherosclerosis/genetics
- Atherosclerosis/metabolism
- Atherosclerosis/pathology
- Atherosclerosis/prevention & control
- Bone Marrow Transplantation
- Cell Adhesion
- Cells, Cultured
- Chemotaxis, Leukocyte
- Disease Models, Animal
- Genotype
- Macrophages/metabolism
- Macrophages/pathology
- Male
- Mice, Inbred C57BL
- Mice, Knockout
- Monocytes/metabolism
- Monocytes/pathology
- Neutrophils/metabolism
- Neutrophils/pathology
- Phenotype
- Plaque, Atherosclerotic
- Receptors, LDL/deficiency
- Receptors, LDL/genetics
- Signal Transduction
- Vascular Cell Adhesion Molecule-1/metabolism
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Affiliation(s)
- Olivier Herbin
- From the Icahn School of Medicine at Mount Sinai, Department of Medicine, The Immunology Institute, New York (O.H., E.G.W., K.A.); Quartzy, Inc, Palo Alto, CA (A.G.R.); and Leon H. Charney Division of Cardiology, Department of Medicine, NYU School of Medicine, New York (B.R., K.J.M.)
| | - Adam G Regelmann
- From the Icahn School of Medicine at Mount Sinai, Department of Medicine, The Immunology Institute, New York (O.H., E.G.W., K.A.); Quartzy, Inc, Palo Alto, CA (A.G.R.); and Leon H. Charney Division of Cardiology, Department of Medicine, NYU School of Medicine, New York (B.R., K.J.M.)
| | - Bhama Ramkhelawon
- From the Icahn School of Medicine at Mount Sinai, Department of Medicine, The Immunology Institute, New York (O.H., E.G.W., K.A.); Quartzy, Inc, Palo Alto, CA (A.G.R.); and Leon H. Charney Division of Cardiology, Department of Medicine, NYU School of Medicine, New York (B.R., K.J.M.)
| | - Erica G Weinstein
- From the Icahn School of Medicine at Mount Sinai, Department of Medicine, The Immunology Institute, New York (O.H., E.G.W., K.A.); Quartzy, Inc, Palo Alto, CA (A.G.R.); and Leon H. Charney Division of Cardiology, Department of Medicine, NYU School of Medicine, New York (B.R., K.J.M.)
| | - Kathryn J Moore
- From the Icahn School of Medicine at Mount Sinai, Department of Medicine, The Immunology Institute, New York (O.H., E.G.W., K.A.); Quartzy, Inc, Palo Alto, CA (A.G.R.); and Leon H. Charney Division of Cardiology, Department of Medicine, NYU School of Medicine, New York (B.R., K.J.M.)
| | - Konstantina Alexandropoulos
- From the Icahn School of Medicine at Mount Sinai, Department of Medicine, The Immunology Institute, New York (O.H., E.G.W., K.A.); Quartzy, Inc, Palo Alto, CA (A.G.R.); and Leon H. Charney Division of Cardiology, Department of Medicine, NYU School of Medicine, New York (B.R., K.J.M.).
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5
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Wallez Y, Riedl SJ, Pasquale EB. Association of the breast cancer antiestrogen resistance protein 1 (BCAR1) and BCAR3 scaffolding proteins in cell signaling and antiestrogen resistance. J Biol Chem 2014; 289:10431-10444. [PMID: 24584939 DOI: 10.1074/jbc.m113.541839] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Most breast cancers are estrogen receptor-positive and treated with antiestrogens, but aberrant signaling networks can induce drug resistance. One of these networks involves the scaffolding protein BCAR1/p130CAS, which regulates cell growth and migration/invasion. A less investigated scaffolding protein that also confers antiestrogen resistance is the SH2 domain-containing protein BCAR3. BCAR1 and BCAR3 bind tightly to each other through their C-terminal domains, thus potentially connecting their associated signaling networks. However, recent studies using BCAR1 and BCAR3 interaction mutants concluded that association between the two proteins is not critical for many of their interrelated activities regulating breast cancer malignancy. We report that these previously used BCAR mutations fail to cause adequate loss-of-function of the complex. By using structure-based BCAR1 and BCAR3 mutants that lack the ability to interact, we show that BCAR3-induced antiestrogen resistance in MCF7 breast cancer cells critically depends on its ability to bind BCAR1. Interaction with BCAR3 increases the levels of phosphorylated BCAR1, ultimately potentiating BCAR1-dependent antiestrogen resistance. Furthermore, antiestrogen resistance in cells overexpressing BCAR1/BCAR3 correlates with increased ERK1/2 activity. Inhibiting ERK1/2 through overexpression of the regulatory protein PEA15 negates the resistance, revealing a key role for ERK1/2 in BCAR1/BCAR3-induced antiestrogen resistance. Reverse-phase protein array data show that PEA15 levels in invasive breast cancers correlate with patient survival, suggesting that PEA15 can override ERK1/2 activation by BCAR1/BCAR3 and other upstream regulators. We further uncovered that the BCAR3-related NSP3 can also promote antiestrogen resistance. Thus, strategies to disrupt BCAR1-BCAR3/NSP3 complexes and associated signaling networks could ultimately lead to new breast cancer therapies.
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Affiliation(s)
- Yann Wallez
- Sanford-Burnham Medical Research Institute, La Jolla, California 92037
| | - Stefan J Riedl
- Sanford-Burnham Medical Research Institute, La Jolla, California 92037
| | - Elena B Pasquale
- Sanford-Burnham Medical Research Institute, La Jolla, California 92037; Department of Pathology, University of California, San Diego California 92093.
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6
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Goldmann WH. Vinculin-p130Cas interaction is critical for focal adhesion dynamics and mechano-transduction. Cell Biol Int 2013; 38:283-6. [PMID: 24497348 DOI: 10.1002/cbin.10204] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2013] [Accepted: 11/01/2013] [Indexed: 11/09/2022]
Abstract
Adherent cells, when mechanically stressed, show a wide range of responses including large-scale changes in their mechanical behaviour and gene expression pattern. This is in part facilitated by activating the focal adhesion (FA) protein p130Cas through force-induced conformational changes that lead to the phosphorylation by src family kinases. Janostiak et al. [Janostiak et al. Cell Mol Life Sci (2013) DOI 10.1007/s00018-013-1450-x] have reported that the phosphorylation site Y12 on the SH3 domain of p130Cas modulates the binding with vinculin, a prominent mechano-coupling protein in FAs. Tension changes in FAs (due to the anchorage of the SH3 domain and C-terminal) bring about an extension of the substrate domain of p130Cas by unmasking the phosphorylation sites. These observations demonstrate that vinculin is an important modulator of the p130Cas-mediated mechano-transduction pathway in cells. The central aim should be now to test that vinculin is critical for p130Cas incorporation into the focal adhesion complex and for transmitting forces to the p130Cas molecule.
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Affiliation(s)
- Wolfgang H Goldmann
- Center for Medical Physics and Technology, Biophysics Group, Friedrich-Alexander-University of Erlangen-Nuremberg, Henkestrasse 91, 91052, Erlangen, Germany
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7
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Garaffo G, Provero P, Molineris I, Pinciroli P, Peano C, Battaglia C, Tomaiuolo D, Etzion T, Gothilf Y, Santoro M, Merlo GR. Profiling, Bioinformatic, and Functional Data on the Developing Olfactory/GnRH System Reveal Cellular and Molecular Pathways Essential for This Process and Potentially Relevant for the Kallmann Syndrome. Front Endocrinol (Lausanne) 2013; 4:203. [PMID: 24427155 PMCID: PMC3876029 DOI: 10.3389/fendo.2013.00203] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/26/2013] [Accepted: 12/18/2013] [Indexed: 11/28/2022] Open
Abstract
During embryonic development, immature neurons in the olfactory epithelium (OE) extend axons through the nasal mesenchyme, to contact projection neurons in the olfactory bulb. Axon navigation is accompanied by migration of the GnRH+ neurons, which enter the anterior forebrain and home in the septo-hypothalamic area. This process can be interrupted at various points and lead to the onset of the Kallmann syndrome (KS), a disorder characterized by anosmia and central hypogonadotropic hypogonadism. Several genes has been identified in human and mice that cause KS or a KS-like phenotype. In mice a set of transcription factors appears to be required for olfactory connectivity and GnRH neuron migration; thus we explored the transcriptional network underlying this developmental process by profiling the OE and the adjacent mesenchyme at three embryonic ages. We also profiled the OE from embryos null for Dlx5, a homeogene that causes a KS-like phenotype when deleted. We identified 20 interesting genes belonging to the following categories: (1) transmembrane adhesion/receptor, (2) axon-glia interaction, (3) scaffold/adapter for signaling, (4) synaptic proteins. We tested some of them in zebrafish embryos: the depletion of five (of six) Dlx5 targets affected axonal extension and targeting, while three (of three) affected GnRH neuron position and neurite organization. Thus, we confirmed the importance of cell-cell and cell-matrix interactions and identified new molecules needed for olfactory connection and GnRH neuron migration. Using available and newly generated data, we predicted/prioritized putative KS-disease genes, by building conserved co-expression networks with all known disease genes in human and mouse. The results show the overall validity of approaches based on high-throughput data and predictive bioinformatics to identify genes potentially relevant for the molecular pathogenesis of KS. A number of candidate will be discussed, that should be tested in future mutation screens.
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Affiliation(s)
- Giulia Garaffo
- Department of Molecular Biotechnology and Health Science, University of Torino, Torino, Italy
| | - Paolo Provero
- Department of Molecular Biotechnology and Health Science, University of Torino, Torino, Italy
| | - Ivan Molineris
- Department of Molecular Biotechnology and Health Science, University of Torino, Torino, Italy
| | - Patrizia Pinciroli
- Department of Medical Biotechnology Translational Medicine (BIOMETRA), University of Milano, Milano, Italy
| | - Clelia Peano
- Institute of Biomedical Technology, National Research Council, ITB-CNR, Segrate, Italy
| | - Cristina Battaglia
- Department of Medical Biotechnology Translational Medicine (BIOMETRA), University of Milano, Milano, Italy
- Institute of Biomedical Technology, National Research Council, ITB-CNR, Segrate, Italy
| | - Daniela Tomaiuolo
- Department of Molecular Biotechnology and Health Science, University of Torino, Torino, Italy
| | - Talya Etzion
- The George S. Wise Faculty of Life Sciences, Department of Neurobiology, Tel-Aviv University, Tel-Aviv, Israel
| | - Yoav Gothilf
- The George S. Wise Faculty of Life Sciences, Department of Neurobiology, Tel-Aviv University, Tel-Aviv, Israel
| | - Massimo Santoro
- Department of Molecular Biotechnology and Health Science, University of Torino, Torino, Italy
| | - Giorgio R. Merlo
- Department of Molecular Biotechnology and Health Science, University of Torino, Torino, Italy
- *Correspondence: Giorgio R. Merlo, Department of Molecular Biotechnology and Health Science, University of Torino, Via Nizza 52, Torino 10126, Italy e-mail:
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8
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Wallez Y, Mace PD, Pasquale EB, Riedl SJ. NSP-CAS Protein Complexes: Emerging Signaling Modules in Cancer. Genes Cancer 2012; 3:382-93. [PMID: 23226576 DOI: 10.1177/1947601912460050] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
The CAS (CRK-associated substrate) family of adaptor proteins comprises 4 members, which share a conserved modular domain structure that enables multiple protein-protein interactions, leading to the assembly of intracellular signaling platforms. Besides their physiological role in signal transduction downstream of a variety of cell surface receptors, CAS proteins are also critical for oncogenic transformation and cancer cell malignancy through associations with a variety of regulatory proteins and downstream effectors. Among the regulatory partners, the 3 recently identified adaptor proteins constituting the NSP (novel SH2-containing protein) family avidly bind to the conserved carboxy-terminal focal adhesion-targeting (FAT) domain of CAS proteins. NSP proteins use an anomalous nucleotide exchange factor domain that lacks catalytic activity to form NSP-CAS signaling modules. Additionally, the NSP SH2 domain can link NSP-CAS signaling assemblies to tyrosine-phosphorylated cell surface receptors. NSP proteins can potentiate CAS function by affecting key CAS attributes such as expression levels, phosphorylation state, and subcellular localization, leading to effects on cell adhesion, migration, and invasion as well as cell growth. The consequences of these activities are well exemplified by the role that members of both families play in promoting breast cancer cell invasiveness and resistance to antiestrogens. In this review, we discuss the intriguing interplay between the NSP and CAS families, with a particular focus on cancer signaling networks.
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Affiliation(s)
- Yann Wallez
- Sanford-Burnham Medical Research Institute, La Jolla, CA, USA
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9
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Nievergall E, Lackmann M, Janes PW. Eph-dependent cell-cell adhesion and segregation in development and cancer. Cell Mol Life Sci 2012; 69:1813-42. [PMID: 22204021 PMCID: PMC11114713 DOI: 10.1007/s00018-011-0900-6] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2011] [Revised: 11/06/2011] [Accepted: 11/28/2011] [Indexed: 01/23/2023]
Abstract
Numerous studies attest to essential roles for Eph receptors and their ephrin ligands in controlling cell positioning and tissue patterning during normal and oncogenic development. These studies suggest multiple, sometimes contradictory, functions of Eph-ephrin signalling, which under different conditions can promote either spreading and cell-cell adhesion or cytoskeletal collapse, cell rounding, de-adhesion and cell-cell segregation. A principle determinant of the balance between these two opposing responses is the degree of receptor/ligand clustering and activation. This equilibrium is likely altered in cancers and modulated by somatic mutations of key Eph family members that have emerged as candidate cancer markers in recent profiling studies. In addition, cross-talk amongst Ephs and with other signalling pathways significantly modulates cell-cell adhesion, both between and within Eph- and ephrin-expressing cell populations. This review summarises our current understanding of how Eph receptors control cell adhesion and morphology, and presents examples demonstrating the importance of these events in normal development and cancer.
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Affiliation(s)
- Eva Nievergall
- Department of Biochemistry and Molecular Biology, Monash University, Wellington Road, Clayton, VIC 3800 Australia
- Present Address: Haematology Department, SA Pathology, Frome Road, Adelaide, SA 5000 Australia
| | - Martin Lackmann
- Department of Biochemistry and Molecular Biology, Monash University, Wellington Road, Clayton, VIC 3800 Australia
| | - Peter W. Janes
- Department of Biochemistry and Molecular Biology, Monash University, Wellington Road, Clayton, VIC 3800 Australia
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10
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Mace PD, Wallez Y, Dobaczewska MK, Lee JJ, Robinson H, Pasquale EB, Riedl SJ. NSP-Cas protein structures reveal a promiscuous interaction module in cell signaling. Nat Struct Mol Biol 2011; 18:1381-7. [PMID: 22081014 PMCID: PMC3230775 DOI: 10.1038/nsmb.2152] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2011] [Accepted: 08/30/2011] [Indexed: 12/16/2022]
Abstract
NSP and Cas family proteins form multidomain signaling platforms that mediate cell migration and invasion through a collection of distinct signaling motifs. Members of each family interact via their respective C-terminal domains, but the mechanism of this association has remained enigmatic. Here we present the crystal structures of the C-terminal domain from the human NSP protein BCAR3 and the complex of NSP3 with p130Cas. BCAR3 adopts the Cdc25-homology fold of Ras GTPase exchange factors, but exhibits a “closed” conformation incapable of enzymatic activity. The NSP3–p130Cas complex structure reveals that this closed conformation is instrumental for interaction of NSP proteins with a focal adhesion-targeting domain present in Cas proteins. This enzyme to adaptor conversion enables high affinity, yet promiscuous, interactions between NSP and Cas proteins and represents an unprecedented mechanistic paradigm linking cellular signaling networks.
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Affiliation(s)
- Peter D Mace
- Program of Apoptosis and Cell Death Research, Cancer Center, Sanford-Burnham Medical Research Institute, La Jolla, California, USA
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11
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The SRC homology 2 domain protein Shep1 plays an important role in the penetration of olfactory sensory axons into the forebrain. J Neurosci 2010; 30:13201-10. [PMID: 20881139 DOI: 10.1523/jneurosci.3289-10.2010] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Shep1 is a multidomain signaling protein that forms a complex with Cas, a key scaffolding component of integrin signaling pathways, to promote the migration of non-neuronal cells. However, the physiological function of Shep1 in the nervous system remains unknown. Interestingly, we found that Shep1 and Cas are both concentrated in the axons of developing olfactory sensory neurons (OSNs). These neurons extend their axons from the olfactory epithelium to the olfactory bulb located at the anterior tip of the forebrain. However, in developing Shep1 knock-out mice, we did not detect penetration of OSN axons across the pial basement membrane surrounding the olfactory bulb, suggesting that Shep1 function is important for the establishment of OSN connections with the olfactory bulb. Interestingly, we observed reduced levels of Cas tyrosine phosphorylation in OSN axons of Shep1 knock-out mice, suggesting compromised Cas signaling function. Indeed, when embedded in a three-dimensional gel of basement membrane proteins, explants from Shep1 knock-out olfactory epithelium extend neuronal processes less efficiently than explants from control epithelium. Furthermore, ectopic expression of Shep1 in non-neuronal cells promotes cell migration through a collagen gel. Later in development, loss of Shep1 function also causes a marked reduction in olfactory bulb size and disruption of bulb lamination, which may be primarily attributable to the defective innervation. The greatly reduced OSN connections and hypoplasia of the olfactory bulb, likely resulting in anosmia, are reminiscent of the symptoms of Kallmann syndrome, a human developmental disease that can be caused by mutations in a growing number of genes.
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12
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SHEP1 partners with CasL to promote marginal zone B-cell maturation. Proc Natl Acad Sci U S A 2010; 107:18944-9. [PMID: 20956287 DOI: 10.1073/pnas.1007558107] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
The marginal zone is a cellular niche bordering the marginal sinus of the spleen that contains specialized B-cell and macrophage subsets poised to capture bloodborne antigens. Marginal zone B cells are retained in this niche by integrin-mediated signaling induced by G protein-coupled receptors (GPCRs) and, likely, the B-cell receptor (BCR). Sphingosine-1-phosphate (S1P) signaling via the S1P family of GPCRs is known to be essential for B-cell localization in the marginal zone, but little is known about the downstream signaling events involved. Here, we demonstrate that the adaptor protein SHEP1 is required for marginal zone B-cell maturation. SHEP1 functions in concert with the scaffolding protein CasL, because we show that SHEP1 and CasL are constitutively associated in B cells. SHEP1 association is required for the BCR or S1P receptor(s) to induce the conversion of CasL into its serine/threonine hyperphosphorylated form, which is important for lymphocyte adhesion and motility. Thus, SHEP1 orchestrates marginal zone B-cell movement and retention as a key downstream effector of the BCR and S1P receptors.
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