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Molyneaux K, Laggner C, Brady‐Kalnay SM. A novel binding pocket in the D2 domain of protein tyrosine phosphatase mu (PTPmu) guides AI screen to identify small molecules that modulate tumour cell adhesion, growth and migration. J Cell Mol Med 2023; 27:3553-3564. [PMID: 37860940 PMCID: PMC10660673 DOI: 10.1111/jcmm.17973] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2023] [Revised: 08/25/2023] [Accepted: 09/16/2023] [Indexed: 10/21/2023] Open
Abstract
Approximately 40% of people will get cancer in their lifetime in the US, and 20% are predicted to die from the condition when it is invasive and metastatic. Targeted screening for drugs that interact with proteins that drive cancer cell growth and migration can lead to new therapies. We screened molecular libraries with the AtomNet® AI-based drug design tool to identify compounds predicted to interact with the cytoplasmic domain of protein tyrosine phosphatase mu. Protein tyrosine phosphatase mu (PTPmu) is proteolytically downregulated in cancers such as glioblastoma generating fragments that stimulate cell survival and migration. Aberrant nuclear localization of PTPmu intracellular fragments drives cancer progression, so we targeted a predicted drug-binding site between the two cytoplasmic phosphatase domains we termed a D2 binding pocket. The function of the D2 domain is controversial with various proposed regulatory functions, making the D2 domain an attractive target for the development of allosteric drugs. Seventy-five of the best-scoring and chemically diverse computational hits predicted to interact with the D2 binding pocket were screened for effects on tumour cell motility and growth in 3D culture as well as in a direct assay for PTPmu-dependent adhesion. We identified two high-priority hits that inhibited the migration and glioma cell sphere formation of multiple glioma tumour cell lines as well as aggregation. We also identified one activator of PTPmu-dependent aggregation, which was able to stimulate cell migration. We propose that the PTPmu D2 binding pocket represents a novel regulatory site and that inhibitors targeting this region may have therapeutic potential for treating cancer.
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Affiliation(s)
- Kathleen Molyneaux
- Department of Molecular Biology & MicrobiologyCase Western Reserve UniversityClevelandOhioUSA
| | | | - Susann M. Brady‐Kalnay
- Department of Molecular Biology & MicrobiologyCase Western Reserve UniversityClevelandOhioUSA
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2
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Abstract
A survey of protein databases indicates that the majority of enzymes exist in oligomeric forms, with about half of those found in the UniProt database being homodimeric. Understanding why many enzymes are in their dimeric form is imperative. Recent developments in experimental and computational techniques have allowed for a deeper comprehension of the cooperative interactions between the subunits of dimeric enzymes. This review aims to succinctly summarize these recent advancements by providing an overview of experimental and theoretical methods, as well as an understanding of cooperativity in substrate binding and the molecular mechanisms of cooperative catalysis within homodimeric enzymes. Focus is set upon the beneficial effects of dimerization and cooperative catalysis. These advancements not only provide essential case studies and theoretical support for comprehending dimeric enzyme catalysis but also serve as a foundation for designing highly efficient catalysts, such as dimeric organic catalysts. Moreover, these developments have significant implications for drug design, as exemplified by Paxlovid, which was designed for the homodimeric main protease of SARS-CoV-2.
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Affiliation(s)
- Ke-Wei Chen
- Lab of Computional Chemistry and Drug Design, State Key Laboratory of Chemical Oncogenomics, Peking University Shenzhen Graduate School, Shenzhen 518055, China
| | - Tian-Yu Sun
- Shenzhen Bay Laboratory, Shenzhen 518132, China
| | - Yun-Dong Wu
- Lab of Computional Chemistry and Drug Design, State Key Laboratory of Chemical Oncogenomics, Peking University Shenzhen Graduate School, Shenzhen 518055, China
- Shenzhen Bay Laboratory, Shenzhen 518132, China
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3
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Chien YC, Wang YS, Sridharan D, Kuo CW, Chien CT, Uchihashi T, Kato K, Angata T, Meng TC, Hsu STD, Khoo KH. High Density of N- and O-Glycosylation Shields and Defines the Structural Dynamics of the Intrinsically Disordered Ectodomain of Receptor-type Protein Tyrosine Phosphatase Alpha. JACS AU 2023; 3:1864-1875. [PMID: 37502146 PMCID: PMC10369406 DOI: 10.1021/jacsau.3c00124] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/17/2023] [Revised: 06/01/2023] [Accepted: 06/01/2023] [Indexed: 07/29/2023]
Abstract
The intracellular phosphatase domain of the receptor-type protein tyrosine phosphatase alpha (PTPRA) is known to regulate various signaling pathways related to cell adhesion through c-Src kinase activation. In contrast, the functional significance of its relatively short, intrinsically disordered, and heavily glycosylated ectodomain remains unclear. Through detailed mass spectrometry analyses of a combination of protease and glycosidase digests, we now provide the first experimental evidence for its site-specific glycosylation pattern. This includes the occurrence of O-glycan at the N-glycosylation sequon among the more than 30 O-glycosylation sites confidently identified beside the 7 N-glycosylation sites. The closely spaced N- and O-glycans appear to have mutually limited the extent of further galactosylation and sialylation. An immature smaller form of full-length PTPRA was found to be deficient in O-glycosylation, most likely due to failure to transit the Golgi. N-glycosylation, on the other hand, is dispensable for cell surface expression and contributes less than the extensive O-glycosylation to the overall solution structure of the ectodomain. The glycosylation information is combined with the overall structural features of the ectodomain derived from small-angle X-ray scattering and high-speed atomic force microscopy monitoring to establish a dynamic structural model of the densely glycosylated PTPRA ectodomain. The observed high structural flexibility, as manifested by continuous transitioning from fully to partially extended and fold-back conformations, suggests that the receptor-type phosphatase is anchored to the membrane and kept mostly at a monomeric state through an ectodomain shaped and fully shielded by glycosylation.
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Affiliation(s)
- Yu-Chun Chien
- Institute
of Biological Chemistry, Academia Sinica, Taipei 11529, Taiwan
- Institute
of Biochemical Sciences, National Taiwan
University, Taipei 10617, Taiwan
| | - Yong-Sheng Wang
- Institute
of Biological Chemistry, Academia Sinica, Taipei 11529, Taiwan
- Institute
of Biochemical Sciences, National Taiwan
University, Taipei 10617, Taiwan
| | - Deepa Sridharan
- Institute
of Biological Chemistry, Academia Sinica, Taipei 11529, Taiwan
| | - Chu-Wei Kuo
- Institute
of Biological Chemistry, Academia Sinica, Taipei 11529, Taiwan
| | - Chih-Ta Chien
- Institute
of Biological Chemistry, Academia Sinica, Taipei 11529, Taiwan
| | - Takayuki Uchihashi
- Department
of Physics, Nagoya University, Nagoya 464-8602, Japan
- Exploratory
Research Center on Life and Living Systems, National Institutes of Natural Sciences, Okazaki 444-8787, Japan
| | - Koichi Kato
- Exploratory
Research Center on Life and Living Systems, National Institutes of Natural Sciences, Okazaki 444-8787, Japan
- Institute
for Molecular Science, National Institutes
of Natural Sciences, Okazaki 444-8787, Japan
- Graduate
School of Pharmaceutical Sciences, Nagoya
City University, Nagoya 467-8603, Japan
| | - Takashi Angata
- Institute
of Biological Chemistry, Academia Sinica, Taipei 11529, Taiwan
- Institute
of Biochemical Sciences, National Taiwan
University, Taipei 10617, Taiwan
| | - Tzu-Ching Meng
- Institute
of Biological Chemistry, Academia Sinica, Taipei 11529, Taiwan
- Institute
of Biochemical Sciences, National Taiwan
University, Taipei 10617, Taiwan
| | - Shang-Te Danny Hsu
- Institute
of Biological Chemistry, Academia Sinica, Taipei 11529, Taiwan
- Institute
of Biochemical Sciences, National Taiwan
University, Taipei 10617, Taiwan
- International
Institute for Sustainability with Knotted Chiral Meta Matter, Hiroshima University, Higashihiroshima 739-8527, Japan
| | - Kay-Hooi Khoo
- Institute
of Biological Chemistry, Academia Sinica, Taipei 11529, Taiwan
- Institute
of Biochemical Sciences, National Taiwan
University, Taipei 10617, Taiwan
- Exploratory
Research Center on Life and Living Systems, National Institutes of Natural Sciences, Okazaki 444-8787, Japan
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4
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Sendo S, Kiosses WB, Yang S, Wu DJ, Lee DWK, Liu L, Aschner Y, Vela AJ, Downey GP, Santelli E, Bottini N. Clustering of phosphatase RPTPα promotes Src signaling and the arthritogenic action of synovial fibroblasts. Sci Signal 2023; 16:eabn8668. [PMID: 37402225 PMCID: PMC10544828 DOI: 10.1126/scisignal.abn8668] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2021] [Accepted: 06/15/2023] [Indexed: 07/06/2023]
Abstract
Receptor-type protein phosphatase α (RPTPα) promotes fibroblast-dependent arthritis and fibrosis, in part, by enhancing the activation of the kinase SRC. Synovial fibroblasts lining joint tissue mediate inflammation and tissue damage, and their infiltration into adjacent tissues promotes disease progression. RPTPα includes an ectodomain and two intracellular catalytic domains (D1 and D2) and, in cancer cells, undergoes inhibitory homodimerization, which is dependent on a D1 wedge motif. Through single-molecule localization and labeled molecule interaction microscopy of migrating synovial fibroblasts, we investigated the role of RPTPα dimerization in the activation of SRC, the migration of synovial fibroblasts, and joint damage in a mouse model of arthritis. RPTPα clustered with other RPTPα and with SRC molecules in the context of actin-rich structures. A known dimerization-impairing mutation in the wedge motif (P210L/P211L) and the deletion of the D2 domain reduced RPTPα-RPTPα clustering; however, it also unexpectedly reduced RPTPα-SRC association. The same mutations also reduced recruitment of RPTPα to actin-rich structures and inhibited SRC activation and cellular migration. An antibody against the RPTPα ectodomain that prevented the clustering of RPTPα also inhibited RPTPα-SRC association and SRC activation and attenuated fibroblast migration and joint damage in arthritic mice. A catalytically inactivating RPTPα-C469S mutation protected mice from arthritis and reduced SRC activation in synovial fibroblasts. We conclude that RPTPα clustering retains it to actin-rich structures to promote SRC-mediated fibroblast migration and can be modulated through the extracellular domain.
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Affiliation(s)
- Sho Sendo
- Dept. of Medicine, University of California San Diego, La Jolla, CA 92093
| | - William B. Kiosses
- Dept. of Medicine, University of California San Diego, La Jolla, CA 92093
- La Jolla Institute for Immunology, La Jolla, CA 92037
| | - Shen Yang
- Dept. of Medicine, University of California San Diego, La Jolla, CA 92093
| | - Dennis J. Wu
- Dept. of Medicine, University of California San Diego, La Jolla, CA 92093
| | - Daniel W. K. Lee
- Dept. of Medicine, University of California San Diego, La Jolla, CA 92093
| | - Lin Liu
- Dept. of Medicine, University of California San Diego, La Jolla, CA 92093
| | - Yael Aschner
- Division of Pulmonary Sciences and Critical Care Medicine, Department of Medicine, University of Colorado, Aurora, Colorado
| | - Allison J. Vela
- Dept. of Medicine, University of California San Diego, La Jolla, CA 92093
| | - Gregory P. Downey
- Division of Pulmonary, Critical Care, and Sleep Medicine, Department of Medicine, National Jewish Health, Denver, Colorado
- Division of Pulmonary Sciences and Critical Care Medicine, Department of Medicine, University of Colorado, Aurora, Colorado
- Department of Biomedical Research, National Jewish Health, Denver, Colorado
- Department of Immunology and Microbiology, University of Colorado, Aurora, Colorado
- Department of Pediatrics, National Jewish Health, Denver, Colorado
| | - Eugenio Santelli
- Dept. of Medicine, University of California San Diego, La Jolla, CA 92093
| | - Nunzio Bottini
- Dept. of Medicine, University of California San Diego, La Jolla, CA 92093
- Department of Medicine, Kao Autoimmunity Institute, Cedars Sinai Medical Center, Los Angeles, CA, USA
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5
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Windheim M, Reubold TF, Aichane K, Gaestel M, Burgert HG. Enforced Dimerization of CD45 by the Adenovirus E3/49K Protein Inhibits T Cell Receptor Signaling. J Virol 2023; 97:e0189822. [PMID: 37125921 PMCID: PMC10231199 DOI: 10.1128/jvi.01898-22] [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: 12/08/2022] [Accepted: 04/07/2023] [Indexed: 05/02/2023] Open
Abstract
Human adenoviruses (HAdVs) are widespread pathogens that generally cause mild infections in immunocompetent individuals but severe or even fatal diseases in immunocompromised patients. In order to counteract the host immune defenses, HAdVs encode various immunomodulatory proteins in the early transcription unit 3 (E3). The E3/49K protein is a highly glycosylated type I transmembrane protein uniquely expressed by species D HAdVs. Its N-terminal ectodomain sec49K is released by metalloprotease-mediated shedding at the cell surface and binds to the receptor-like protein tyrosine phosphatase CD45, a critical regulator of leukocyte activation and functions. It remained elusive which domains of CD45 and E3/49K are involved in the interaction and whether such an interaction can also occur on the cell surface with membrane-anchored full-length E3/49K. Here, we show that the two extracellular domains R1 and R2 of E3/49K bind to the same site in the domain d3 of CD45. This interaction enforces the dimerization of CD45, causing the inhibition of T cell receptor signaling. Intriguingly, the membrane-anchored E3/49K appears to be designed like a "molecular fishing rod" using an extended disordered region of E3/49K as a "fishing line" to bridge the distance between the plasma membrane of infected cells and the CD45 binding site on T cells to effectively position the domains R1 and R2 as baits for CD45 binding. This design strongly suggests that both secreted sec49K as well as membrane-anchored full-length E3/49K have immunomodulatory functions. The forced dimerization of CD45 may be applied as a therapeutic strategy in chronic inflammatory disorders and cancer. IMPORTANCE The battle between viruses and their hosts is an ongoing arms race. Whereas the host tries to detect and eliminate the virus, the latter counteracts such antiviral measures to replicate and spread. Adenoviruses have evolved various mechanisms to evade the human immune response. The E3/49K protein of species D adenoviruses mediates the inhibition of immune cell function via binding to the protein tyrosine phosphatase CD45. Here, we show that E3/49K triggers the dimerization of CD45 and thereby inhibits its phosphatase activity. Intriguingly, the membrane-anchored E3/49K seems to be designed like a "molecular fishing rod" with the two CD45 binding domains of E3/49K as baits positioned at the end of an extended disordered region reminiscent of a fishing line. The adenoviral strategy to inhibit CD45 activity by forced dimerization may be used for therapeutic intervention in autoimmune diseases or to prevent graft rejection after transplantation.
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Affiliation(s)
- Mark Windheim
- Institute of Cell Biochemistry, Hannover Medical School, Hannover, Germany
| | - Thomas F. Reubold
- Institute for Biophysical Chemistry, Hannover Medical School, Hannover, Germany
| | - Khadija Aichane
- Institute of Cell Biochemistry, Hannover Medical School, Hannover, Germany
| | - Matthias Gaestel
- Institute of Cell Biochemistry, Hannover Medical School, Hannover, Germany
| | - Hans-Gerhard Burgert
- Institute of Virology, University Medical Center, Albert-Ludwigs-University Freiburg, Freiburg, Germany
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6
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Glucose-mediated N-glycosylation of RPTPα affects its subcellular localization and Src activation. Oncogene 2023; 42:1058-1071. [PMID: 36765146 DOI: 10.1038/s41388-023-02622-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Revised: 01/28/2023] [Accepted: 02/01/2023] [Indexed: 02/12/2023]
Abstract
Receptor-type protein tyrosine phosphatase α (RPTPα) is one of the typical PTPs that play indispensable roles in many cellular processes associated with cancers. It has been considered as the most powerful regulatory oncogene for Src activation, however it is unclear how its biological function is regulated by post-translational modifications. Here, we show that the extracellular segment of RPTPα is highly N-glycosylated precisely at N21, N36, N68, N80, N86, N104 and N124 sites. Such N-glycosylation modifications mediated by glucose concentration alter the subcellular localization of RPTPα from Golgi apparatus to plasma membrane, enhance the interaction of RPTPα with Src, which in turn enhances the activation of Src and ultimately promotes tumor development. Our results identified the N-glycosylation modifications of RPTPα, and linked it to glucose starvation and Src activation for promoting tumor development, which provides new evidence for the potential antitumor therapy.
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7
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Marciano S, Dey D, Listov D, Fleishman SJ, Sonn-Segev A, Mertens H, Busch F, Kim Y, Harvey SR, Wysocki VH, Schreiber G. Protein quaternary structures in solution are a mixture of multiple forms. Chem Sci 2022; 13:11680-11695. [PMID: 36320402 PMCID: PMC9555727 DOI: 10.1039/d2sc02794a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2022] [Accepted: 09/21/2022] [Indexed: 11/21/2022] Open
Abstract
Over half the proteins in the E. coli cytoplasm form homo or hetero-oligomeric structures. Experimentally determined structures are often considered in determining a protein's oligomeric state, but static structures miss the dynamic equilibrium between different quaternary forms. The problem is exacerbated in homo-oligomers, where the oligomeric states are challenging to characterize. Here, we re-evaluated the oligomeric state of 17 different bacterial proteins across a broad range of protein concentrations and solutions by native mass spectrometry (MS), mass photometry (MP), size exclusion chromatography (SEC), and small-angle X-ray scattering (SAXS), finding that most exhibit several oligomeric states. Surprisingly, some proteins did not show mass-action driven equilibrium between the oligomeric states. For approximately half the proteins, the predicted oligomeric forms described in publicly available databases underestimated the complexity of protein quaternary structures in solution. Conversely, AlphaFold multimer provided an accurate description of the potential multimeric states for most proteins, suggesting that it could help resolve uncertainties on the solution state of many proteins.
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Affiliation(s)
- Shir Marciano
- Department of Biomolecular Sciences, Weizmann Institute of Science Rehovot Israel
| | - Debabrata Dey
- Department of Biomolecular Sciences, Weizmann Institute of Science Rehovot Israel
| | - Dina Listov
- Department of Biomolecular Sciences, Weizmann Institute of Science Rehovot Israel
| | - Sarel J Fleishman
- Department of Biomolecular Sciences, Weizmann Institute of Science Rehovot Israel
| | - Adar Sonn-Segev
- Refeyn Ltd 1 Electric Avenue, Ferry Hinksey Road Oxford OX2 0BY UK
| | - Haydyn Mertens
- Hamburg Outstation, European Molecular Biology Laboratory Notkestrasse 85 Hamburg 22607 Germany
| | - Florian Busch
- Department of Chemistry and Biochemistry, Resource for Native Mass Spectrometry Guided Structural Biology, The Ohio State University Columbus OH 43210 USA
| | - Yongseok Kim
- Department of Chemistry and Biochemistry, Resource for Native Mass Spectrometry Guided Structural Biology, The Ohio State University Columbus OH 43210 USA
| | - Sophie R Harvey
- Department of Chemistry and Biochemistry, Resource for Native Mass Spectrometry Guided Structural Biology, The Ohio State University Columbus OH 43210 USA
| | - Vicki H Wysocki
- Department of Chemistry and Biochemistry, Resource for Native Mass Spectrometry Guided Structural Biology, The Ohio State University Columbus OH 43210 USA
| | - Gideon Schreiber
- Department of Biomolecular Sciences, Weizmann Institute of Science Rehovot Israel
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8
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Boni C, Sorio C. The Role of the Tumor Suppressor Gene Protein Tyrosine Phosphatase Gamma in Cancer. Front Cell Dev Biol 2022; 9:768969. [PMID: 35071225 PMCID: PMC8766859 DOI: 10.3389/fcell.2021.768969] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Accepted: 12/16/2021] [Indexed: 12/31/2022] Open
Abstract
Members of the Protein Tyrosine Phosphatase (PTPs) family are associated with growth regulation and cancer development. Acting as natural counterpart of tyrosine kinases (TKs), mainly involved in crucial signaling pathways such as regulation of cell cycle, proliferation, invasion and angiogenesis, they represent key parts of complex physiological homeostatic mechanisms. Protein tyrosine phosphatase gamma (PTPRG) is classified as a R5 of the receptor type (RPTPs) subfamily and is broadly expressed in various isoforms in different tissues. PTPRG is considered a tumor-suppressor gene (TSG) mapped on chromosome 3p14-21, a region frequently subject to loss of heterozygosity in various tumors. However, reported mechanisms of PTPRG downregulation include missense mutations, ncRNA gene regulation and epigenetic silencing by hypermethylation of CpG sites on promoter region causing loss of function of the gene product. Inactive forms or total loss of PTPRG protein have been described in sporadic and Lynch syndrome colorectal cancer, nasopharyngeal carcinoma, ovarian, breast, and lung cancers, gastric cancer or diseases affecting the hematopoietic compartment as Lymphoma and Leukemia. Noteworthy, in Central Nervous System (CNS) PTPRZ/PTPRG appears to be crucial in maintaining glioblastoma cell-related neuronal stemness, carving out a pathological functional role also in this tissue. In this review, we will summarize the current knowledge on the role of PTPRG in various human cancers.
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Affiliation(s)
- Christian Boni
- Department of Medicine, General Pathology Division, University of Verona, Verona, Italy
| | - Claudio Sorio
- Department of Medicine, General Pathology Division, University of Verona, Verona, Italy
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9
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Gaber A, Pavšič M. Modeling and Structure Determination of Homo-Oligomeric Proteins: An Overview of Challenges and Current Approaches. Int J Mol Sci 2021; 22:9081. [PMID: 34445785 PMCID: PMC8396596 DOI: 10.3390/ijms22169081] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Revised: 08/20/2021] [Accepted: 08/20/2021] [Indexed: 12/12/2022] Open
Abstract
Protein homo-oligomerization is a very common phenomenon, and approximately half of proteins form homo-oligomeric assemblies composed of identical subunits. The vast majority of such assemblies possess internal symmetry which can be either exploited to help or poses challenges during structure determination. Moreover, aspects of symmetry are critical in the modeling of protein homo-oligomers either by docking or by homology-based approaches. Here, we first provide a brief overview of the nature of protein homo-oligomerization. Next, we describe how the symmetry of homo-oligomers is addressed by crystallographic and non-crystallographic symmetry operations, and how biologically relevant intermolecular interactions can be deciphered from the ordered array of molecules within protein crystals. Additionally, we describe the most important aspects of protein homo-oligomerization in structure determination by NMR. Finally, we give an overview of approaches aimed at modeling homo-oligomers using computational methods that specifically address their internal symmetry and allow the incorporation of other experimental data as spatial restraints to achieve higher model reliability.
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10
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Ismail MA, Samara M, Al Sayab A, Alsharshani M, Yassin MA, Varadharaj G, Vezzalini M, Tomasello L, Monne M, Morsi H, Qoronfleh MW, Zayed H, Cook R, Sorio C, Modjtahedi H, Al-Dewik NI. Aberrant DNA methylation of PTPRG as one possible mechanism of its under-expression in CML patients in the State of Qatar. Mol Genet Genomic Med 2020; 8:e1319. [PMID: 32700424 PMCID: PMC7549574 DOI: 10.1002/mgg3.1319] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Revised: 04/24/2020] [Accepted: 04/27/2020] [Indexed: 02/06/2023] Open
Abstract
Background Several studies showed that aberrant DNA methylation is involved in leukemia and cancer pathogenesis. Protein tyrosine phosphatase receptor gamma (PTPRG) expression is a natural inhibitory mechanism that is downregulated in chronic myeloid leukemia (CML) disease. The mechanism behind its downregulation has not been fully elucidated yet. Aim This study aimed to investigate the CpG methylation status at the PTPRG locus in CML patients. Methods Peripheral blood samples from CML patients at time of diagnosis [no tyrosine kinase inhibitors (TKIs)] (n = 13), failure to (TKIs) treatment (n = 13) and healthy controls (n = 6) were collected. DNA was extracted and treated with bisulfite treatment, followed by PCR, sequencing of 25 CpG sites in the promoter region and 26 CpG sites in intron‐1 region of PTPRG. The bisulfite sequencing technique was employed as a high‐resolution method. Results CML groups (new diagnosed and failed treatment) showed significantly higher methylation levels in the promoter and intron‐1 regions of PTPRG compared to the healthy group. There were also significant differences in methylation levels of CpG sites in the promoter and intron‐1 regions amongst the groups. Conclusion Aberrant methylation of PTPRG is potentially one of the possible mechanisms of PTPRG downregulation detected in CML.
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Affiliation(s)
- Mohamed A Ismail
- School of Life Science, Pharmacy and Chemistry, Faculty of Science, Engineering & ComputingFaculty of Science, Engineering & Computing, Kingston University London, Kingston-Upon-Thames, UK.,Interim Translational Research Institute (iTRI), Hamad Medical Corporation (HMC), Doha, Qatar
| | - Muthanna Samara
- Department of Psychology, Kingston University London, Kingston upon Thames, London, UK
| | - Ali Al Sayab
- Interim Translational Research Institute (iTRI), Hamad Medical Corporation (HMC), Doha, Qatar
| | - Mohamed Alsharshani
- Diagnostic Genetics Division (DGD), Department of Laboratory Medicine and Pathology (DLMP), Hamad Medical Corporation (HMC), Doha, Qatar
| | - Mohamed A Yassin
- Department of Medical Oncology, National Centre for Cancer Care and Research, Hamad Medical Corporation (HMC), Doha, Qatar
| | | | - Marzia Vezzalini
- General Pathology Division, Department of Medicine, University of Verona, Verona, Italy
| | - Luisa Tomasello
- Wexner Medical Center, Biomedical Research Tower, The Ohio State University, Columbus, OH, USA
| | - Maria Monne
- Centro di Diagnostica Biomolecolare e Citogenetica Emato-Oncologica, San Francesco" Hospital, Nuoro, Italy
| | - Hisham Morsi
- Quality of Life unit, National Center for Cancer Care and Research, (NCCCR), Hamad Medical Corporation (HMC), Doha, Qatar
| | - M Walid Qoronfleh
- World Innovation Summit for Healthcare (WISH), Qatar Foundation, Doha, Qatar
| | - Hatem Zayed
- Department of Biomedical Sciences, Biomedical Research Center, College of Health Sciences, QU Health, Qatar University, Doha, Qatar
| | - Richard Cook
- School of Life Science, Pharmacy and Chemistry, Faculty of Science, Engineering & ComputingFaculty of Science, Engineering & Computing, Kingston University London, Kingston-Upon-Thames, UK
| | - Claudio Sorio
- General Pathology Division, Department of Medicine, University of Verona, Verona, Italy
| | - Helmout Modjtahedi
- School of Life Science, Pharmacy and Chemistry, Faculty of Science, Engineering & ComputingFaculty of Science, Engineering & Computing, Kingston University London, Kingston-Upon-Thames, UK
| | - Nader I Al-Dewik
- School of Life Science, Pharmacy and Chemistry, Faculty of Science, Engineering & ComputingFaculty of Science, Engineering & Computing, Kingston University London, Kingston-Upon-Thames, UK.,Qatar Medical Genetic Center (QMGC), Hamad General Hospital (HGH), and Interim Translational Research Institute (iTRI), Hamad Medical Corporation (HMC), Doha, Qatar.,College of Health and Life Science (CHLS), Hamad Bin Khalifa University (HBKU), Doha, Qatar.,Department of Pediatrics, Women's Wellness and Research Center (WWRC), HMC, Doha, Qatar
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11
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Reiterer V, Pawłowski K, Desrochers G, Pause A, Sharpe HJ, Farhan H. The dead phosphatases society: a review of the emerging roles of pseudophosphatases. FEBS J 2020; 287:4198-4220. [PMID: 32484316 DOI: 10.1111/febs.15431] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Revised: 05/12/2020] [Accepted: 05/27/2020] [Indexed: 12/11/2022]
Abstract
Phosphatases are a diverse family of enzymes, comprising at least 10 distinct protein folds. Like most other enzyme families, many have sequence variations that predict an impairment or loss of catalytic activity classifying them as pseudophosphatases. Research on pseudoenzymes is an emerging area of interest, with new biological functions repurposed from catalytically active relatives. Here, we provide an overview of the pseudophosphatases identified to date in all major phosphatase families. We will highlight the degeneration of the various catalytic sequence motifs and discuss the challenges associated with the experimental determination of catalytic inactivity. We will also summarize the role of pseudophosphatases in various diseases and discuss the major challenges and future directions in this field.
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Affiliation(s)
| | | | - Guillaume Desrochers
- Department of Biochemistry, McGill University, Montréal, QC, Canada.,Goodman Cancer Research Centre, McGill University, Montréal, QC, Canada
| | - Arnim Pause
- Department of Biochemistry, McGill University, Montréal, QC, Canada.,Goodman Cancer Research Centre, McGill University, Montréal, QC, Canada
| | | | - Hesso Farhan
- Institute of Basic Medical Sciences, University of Oslo, Norway
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12
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Soni N, Swain SK, Kant R, Singh A, Ravichandran R, Verma SK, Panda PK, Suar M. Landscape of ROD9 Island: Functional annotations and biological network of hypothetical proteins in Salmonella enterica. Comput Biol Chem 2019; 83:107110. [PMID: 31445418 DOI: 10.1016/j.compbiolchem.2019.107110] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2018] [Revised: 07/16/2019] [Accepted: 08/13/2019] [Indexed: 01/01/2023]
Abstract
Salmonella, an Enterobacteria is a therapeutically important pathogen for the host. The advancement of genome sequencing of S. enterica serovar Enteritidis have identified a distinct ROD9 pathogenic island, imparting virulence. The occurrence of 17 ROD9 hypothetical proteins, necessitates subsequent bioinformatics approach for structural and functional aspects of protein-protein relations or networks in different pathogenic phenotypes express. A collective analysis using predictive bioinformatics tools that includes NCBI-BLASTp and BLAST2GO annotated the motif patterns and functional significance. The VFDB identified 10 virulence proteins at both genomic and metagenomic level. Phylogenetic analysis revealed a divergent and convergent relationship between 17 ROD9 and 41 SP-1 proteins. Here, combining a comprehensive approach from sequence based, motif recognitions, domain identification, virulence ability to structural modelling provides a precise function to ROD9 proteins biological network, for which no experimental information is available.
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Affiliation(s)
- Nikita Soni
- School of Biotechnology and Bioinformatics, D. Y. Patil (Deemed to be University), Navi Mumbai, India
| | | | - Ravi Kant
- University of Delhi, New Delhi, India
| | - Aditya Singh
- School of Biotechnology and Bioinformatics, D. Y. Patil (Deemed to be University), Navi Mumbai, India
| | - Rahul Ravichandran
- School of Chemical and Biotechnology, SASTRA University, Tamil Nadu, India
| | - Suresh K Verma
- Institute of Environmental Medicine (IMM), C6, Molecular Toxicology, Karolinska Institutet, Sweden
| | - Pritam Kumar Panda
- Division of Pediatric Hematology and Oncology, University Medical Center, University of Freiburg, Germany.
| | - Mrutyunjay Suar
- School of Biotechnology, KIIT University, Bhubaneswar, India.
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13
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Yu ZH, Zhang ZY. Regulatory Mechanisms and Novel Therapeutic Targeting Strategies for Protein Tyrosine Phosphatases. Chem Rev 2018; 118:1069-1091. [PMID: 28541680 PMCID: PMC5812791 DOI: 10.1021/acs.chemrev.7b00105] [Citation(s) in RCA: 70] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
An appropriate level of protein phosphorylation on tyrosine is essential for cells to react to extracellular stimuli and maintain cellular homeostasis. Faulty operation of signal pathways mediated by protein tyrosine phosphorylation causes numerous human diseases, which presents enormous opportunities for therapeutic intervention. While the importance of protein tyrosine kinases in orchestrating the tyrosine phosphorylation networks and in target-based drug discovery has long been recognized, the significance of protein tyrosine phosphatases (PTPs) in cellular signaling and disease biology has historically been underappreciated, due to a large extent to an erroneous assumption that they are largely constitutive and housekeeping enzymes. Here, we provide a comprehensive examination of a number of regulatory mechanisms, including redox modulation, allosteric regulation, and protein oligomerization, that control PTP activity. These regulatory mechanisms are integral to the myriad PTP-mediated biochemical events and reinforce the concept that PTPs are indispensable and specific modulators of cellular signaling. We also discuss how disruption of these PTP regulatory mechanisms can cause human diseases and how these diverse regulatory mechanisms can be exploited for novel therapeutic development.
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Affiliation(s)
- Zhi-Hong Yu
- Department of Medicinal Chemistry and Molecular Pharmacology, Department of Chemistry, Center for Cancer Research, and Institute for Drug Discovery, Purdue University, 720 Clinic Drive, West Lafayette, IN 47907
| | - Zhong-Yin Zhang
- Department of Medicinal Chemistry and Molecular Pharmacology, Department of Chemistry, Center for Cancer Research, and Institute for Drug Discovery, Purdue University, 720 Clinic Drive, West Lafayette, IN 47907
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14
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Hendriks W, Bourgonje A, Leenders W, Pulido R. Proteinaceous Regulators and Inhibitors of Protein Tyrosine Phosphatases. Molecules 2018; 23:molecules23020395. [PMID: 29439552 PMCID: PMC6016963 DOI: 10.3390/molecules23020395] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Revised: 02/09/2018] [Accepted: 02/09/2018] [Indexed: 12/18/2022] Open
Abstract
Proper control of the phosphotyrosine content in signal transduction proteins is essential for normal cell behavior and is lost in many pathologies. Attempts to normalize aberrant tyrosine phosphorylation levels in disease states currently involve either the application of small compounds that inhibit tyrosine kinases (TKs) or the addition of growth factors or their mimetics to boost receptor-type TK activity. Therapies that target the TK enzymatic counterparts, the multi-enzyme family of protein tyrosine phosphatases (PTPs), are still lacking despite their undisputed involvement in human diseases. Efforts to pharmacologically modulate PTP activity have been frustrated by the conserved structure of the PTP catalytic core, providing a daunting problem with respect to target specificity. Over the years, however, many different protein interaction-based regulatory mechanisms that control PTP activity have been uncovered, providing alternative possibilities to control PTPs individually. Here, we review these regulatory principles, discuss existing biologics and proteinaceous compounds that affect PTP activity, and mention future opportunities to drug PTPs via these regulatory concepts.
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Affiliation(s)
- Wiljan Hendriks
- Department of Cell Biology, Radboud University Medical Center, Geert Grooteplein 26, 6525 GA Nijmegen, The Netherlands.
| | - Annika Bourgonje
- Department of Cell Biology, Radboud University Medical Center, Geert Grooteplein 26, 6525 GA Nijmegen, The Netherlands.
| | - William Leenders
- Department of Biochemistry, Radboud University Medical Center, Geert Grooteplein 26, 6525 GA Nijmegen, The Netherlands.
| | - Rafael Pulido
- Biomarkers in Cancer Unit, Biocruces Health Research Institute, 48903 Barakaldo, Spain.
- IKERBASQUE, Basque Foundation for Science, Bilbao, Spain.
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15
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Characterization of homodimer interfaces with cross-linking mass spectrometry and isotopically labeled proteins. Nat Protoc 2018; 13:431-458. [PMID: 29388937 DOI: 10.1038/nprot.2017.113] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Cross-linking coupled with mass spectrometry (XL-MS) has emerged as a powerful strategy for the identification of protein-protein interactions, characterization of interaction regions, and obtainment of structural information on proteins and protein complexes. In XL-MS, proteins or complexes are covalently stabilized with cross-linkers and digested, followed by identification of the cross-linked peptides by tandem mass spectrometry (MS/MS). This provides spatial constraints that enable modeling of protein (complex) structures and regions of interaction. However, most XL-MS approaches are not capable of differentiating intramolecular from intermolecular links in multimeric complexes, and therefore they cannot be used to study homodimer interfaces. We have recently developed an approach that overcomes this limitation by stable isotope-labeling of one of the two monomers, thereby creating a homodimer with one 'light' and one 'heavy' monomer. Here, we describe a step-by-step protocol for stable isotope-labeling, followed by controlled denaturation and refolding in the presence of the wild-type protein. The resulting light-heavy dimers are cross-linked, digested, and analyzed by mass spectrometry. We show how to quantitatively analyze the corresponding data with SIM-XL, an XL-MS software with a module tailored toward the MS/MS data from homodimers. In addition, we provide a video tutorial of the data analysis with this protocol. This protocol can be performed in ∼14 d, and requires basic biochemical and mass spectrometry skills.
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16
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Regulation of receptor-type protein tyrosine phosphatases by their C-terminal tail domains. Biochem Soc Trans 2017; 44:1295-1303. [PMID: 27911712 DOI: 10.1042/bst20160141] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Revised: 07/06/2016] [Accepted: 07/11/2016] [Indexed: 01/10/2023]
Abstract
Protein tyrosine phosphatases (PTPs) perform specific functions in vivo, despite being vastly outnumbered by their substrates. Because of this and due to the central roles PTPs play in regulating cellular function, PTP activity is regulated by a large variety of molecular mechanisms. We review evidence that indicates that the divergent C-terminal tail sequences (C-terminal domains, CTDs) of receptor-type PTPs (RPTPs) help regulate RPTP function by controlling intermolecular associations in a way that is itself subject to physiological regulation. We propose that the CTD of each RPTP defines an 'interaction code' that helps determine molecules it will interact with under various physiological conditions, thus helping to regulate and diversify PTP function.
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17
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Cellular Dynamics Controlled by Phosphatases. J Indian Inst Sci 2017. [DOI: 10.1007/s41745-016-0016-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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18
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Stability of proICA512/IA-2 and its targeting to insulin secretory granules require β4-sheet-mediated dimerization of its ectodomain in the endoplasmic reticulum. Mol Cell Biol 2015; 35:914-27. [PMID: 25561468 DOI: 10.1128/mcb.00994-14] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The type 1 diabetes autoantigen ICA512/IA-2/RPTPN is a receptor protein tyrosine phosphatase of the insulin secretory granules (SGs) which regulates the size of granule stores, possibly via cleavage/signaling of its cytosolic tail. The role of its extracellular region remains unknown. Structural studies indicated that β2- or β4-strands in the mature ectodomain (ME ICA512) form dimers in vitro. Here we show that ME ICA512 prompts proICA512 dimerization in the endoplasmic reticulum. Perturbation of ME ICA512 β2-strand N-glycosylation upon S508A replacement allows for proICA512 dimerization, O-glycosylation, targeting to granules, and conversion, which are instead precluded upon G553D replacement in the ME ICA512 β4-strand. S508A/G553D and N506A/G553D double mutants dimerize but remain in the endoplasmic reticulum. Removal of the N-terminal fragment (ICA512-NTF) preceding ME ICA512 allows an ICA512-ΔNTF G553D mutant to exit the endoplasmic reticulum, and ICA512-ΔNTF is constitutively delivered to the cell surface. The signal for SG sorting is located within the NTF RESP18 homology domain (RESP18-HD), whereas soluble NTF is retained in the endoplasmic reticulum. Hence, we propose that the ME ICA512 β2-strand fosters proICA512 dimerization until NTF prevents N506 glycosylation. Removal of this constraint allows for proICA512 β4-strand-induced dimerization, exit from the endoplasmic reticulum, O-glycosylation, and RESP18-HD-mediated targeting to granules.
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19
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Reshetnyak AV, Opatowsky Y, Boggon TJ, Folta-Stogniew E, Tome F, Lax I, Schlessinger J. The strength and cooperativity of KIT ectodomain contacts determine normal ligand-dependent stimulation or oncogenic activation in cancer. Mol Cell 2014; 57:191-201. [PMID: 25544564 DOI: 10.1016/j.molcel.2014.11.021] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2014] [Revised: 10/14/2014] [Accepted: 11/18/2014] [Indexed: 12/22/2022]
Abstract
The receptor tyrosine kinase KIT plays an important role in development of germ cells, hematopoietic cells, and interstitial pacemaker cells. Oncogenic KIT mutations play an important "driver" role in gastrointestinal stromal tumors, acute myeloid leukemias, and melanoma, among other cancers. Here we describe the crystal structure of a recurring somatic oncogenic mutation located in the C-terminal Ig-like domain (D5) of the ectodomain, rendering KIT tyrosine kinase activity constitutively activated. The structural analysis, together with biochemical and biophysical experiments and detailed analyses of the activities of a variety of oncogenic KIT mutations, reveals that the strength of homotypic contacts and the cooperativity in the action of D4D5 regions determines whether KIT is normally regulated or constitutively activated in cancers. We propose that cooperative interactions mediated by multiple weak homotypic contacts between receptor molecules are responsible for regulating normal ligand-dependent or oncogenic RTK activation via a "zipper-like" mechanism for receptor activation.
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Affiliation(s)
- Andrey V Reshetnyak
- Department of Pharmacology, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Yarden Opatowsky
- Department of Pharmacology, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Titus J Boggon
- Department of Pharmacology, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Ewa Folta-Stogniew
- The Biophysical Resource, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Francisco Tome
- Department of Pharmacology, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Irit Lax
- Department of Pharmacology, Yale University School of Medicine, New Haven, CT 06520, USA.
| | - Joseph Schlessinger
- Department of Pharmacology, Yale University School of Medicine, New Haven, CT 06520, USA.
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20
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Identification of receptor protein tyrosine phosphatases (RPTPs) as regulators of receptor tyrosine kinases (RTKs) using an RPTP siRNA-RTK substrate screen. Methods Mol Biol 2014; 1233:111-20. [PMID: 25319894 DOI: 10.1007/978-1-4939-1789-1_11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/21/2023]
Abstract
Receptor tyrosine kinase (RTK) signaling exists in equilibrium between RTK tyrosyl phosphorylation and RTK tyrosyl dephosphorylation. Despite a detailed understanding of RTK tyrosyl phosphorylation, much less is known about RTK tyrosyl dephosphorylation. The receptor PTPs (RPTPs) are outstanding targets for the dephosphorylation of RTKs because of their mutual membrane proximity. In this chapter, we describe how to identify RPTPs that modulate the activity of RTKs using a siRNA screen and commercially available proteomic applications. The validation of putative RTKs as RPTP substrates using substrate-trapping approaches is detailed.
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21
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Lee H, Yi JS, Lawan A, Min K, Bennett AM. Mining the function of protein tyrosine phosphatases in health and disease. Semin Cell Dev Biol 2014; 37:66-72. [PMID: 25263013 DOI: 10.1016/j.semcdb.2014.09.021] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2014] [Accepted: 09/21/2014] [Indexed: 12/31/2022]
Abstract
Protein tyrosine phosphatases (PTPs) play a crucial role in the regulation of human health and it is now clear that PTP dysfunction is causal to a variety of human diseases. Research in the PTP field has accelerated dramatically over the last decade fueled by cutting-edge technologies in genomic and proteomic techniques. This system-wide non-biased approach when applied to the discovery of PTP function has led to the elucidation of new and unanticipated roles for the PTPs. These discoveries, driven by genomic and proteomic approaches, have uncovered novel PTP findings that range from those that describe fundamental cell signaling mechanisms to implications for PTPs as novel therapeutic targets for the treatment of human disease. This review will discuss how new PTP functions have been uncovered through studies that have utilized genomic and proteomic technologies and strategies.
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Affiliation(s)
- Hojin Lee
- Department of Pharmacology, Yale University School of Medicine, New Haven, CT, USA
| | - Jae-Sung Yi
- Department of Pharmacology, Yale University School of Medicine, New Haven, CT, USA
| | - Ahmed Lawan
- Department of Pharmacology, Yale University School of Medicine, New Haven, CT, USA
| | - Kisuk Min
- Department of Pharmacology, Yale University School of Medicine, New Haven, CT, USA
| | - Anton M Bennett
- Department of Pharmacology, Yale University School of Medicine, New Haven, CT, USA; Program in Integrative Cell Signaling and Neurobiology of Metabolism, Yale University School of Medicine, New Haven, CT, USA.
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22
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Brooks AJ, Dai W, O'Mara ML, Abankwa D, Chhabra Y, Pelekanos RA, Gardon O, Tunny KA, Blucher KM, Morton CJ, Parker MW, Sierecki E, Gambin Y, Gomez GA, Alexandrov K, Wilson IA, Doxastakis M, Mark AE, Waters MJ. Mechanism of activation of protein kinase JAK2 by the growth hormone receptor. Science 2014; 344:1249783. [PMID: 24833397 DOI: 10.1126/science.1249783] [Citation(s) in RCA: 280] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Signaling from JAK (Janus kinase) protein kinases to STAT (signal transducers and activators of transcription) transcription factors is key to many aspects of biology and medicine, yet the mechanism by which cytokine receptors initiate signaling is enigmatic. We present a complete mechanistic model for activation of receptor-bound JAK2, based on an archetypal cytokine receptor, the growth hormone receptor. For this, we used fluorescence resonance energy transfer to monitor positioning of the JAK2 binding motif in the receptor dimer, substitution of the receptor extracellular domains with Jun zippers to control the position of its transmembrane (TM) helices, atomistic modeling of TM helix movements, and docking of the crystal structures of the JAK2 kinase and its inhibitory pseudokinase domain with an opposing kinase-pseudokinase domain pair. Activation of the receptor dimer induced a separation of its JAK2 binding motifs, driven by a ligand-induced transition from a parallel TM helix pair to a left-handed crossover arrangement. This separation leads to removal of the pseudokinase domain from the kinase domain of the partner JAK2 and pairing of the two kinase domains, facilitating trans-activation. This model may well generalize to other class I cytokine receptors.
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Affiliation(s)
- Andrew J Brooks
- The University of Queensland, Institute for Molecular Bioscience (IMB), St Lucia, Queensland 4072, Australia.
| | - Wei Dai
- Department of Chemical and Biomolecular Engineering, University of Houston, Houston, TX 77004, USA
| | - Megan L O'Mara
- The University of Queensland, School of Chemistry and Molecular Biosciences, St Lucia, Queensland 4072, Australia
| | - Daniel Abankwa
- The University of Queensland, Institute for Molecular Bioscience (IMB), St Lucia, Queensland 4072, Australia
| | - Yash Chhabra
- The University of Queensland, Institute for Molecular Bioscience (IMB), St Lucia, Queensland 4072, Australia
| | - Rebecca A Pelekanos
- The University of Queensland, Institute for Molecular Bioscience (IMB), St Lucia, Queensland 4072, Australia
| | - Olivier Gardon
- The University of Queensland, Institute for Molecular Bioscience (IMB), St Lucia, Queensland 4072, Australia
| | - Kathryn A Tunny
- The University of Queensland, Institute for Molecular Bioscience (IMB), St Lucia, Queensland 4072, Australia
| | - Kristopher M Blucher
- The University of Queensland, Institute for Molecular Bioscience (IMB), St Lucia, Queensland 4072, Australia
| | - Craig J Morton
- Biota Structural Biology Laboratory and Australian Cancer Research Foundation (ACRF) Rational Drug Discovery Centre, St Vincent's Institute of Medical Research, Fitzroy, Victoria 3065, Australia
| | - Michael W Parker
- Biota Structural Biology Laboratory and Australian Cancer Research Foundation (ACRF) Rational Drug Discovery Centre, St Vincent's Institute of Medical Research, Fitzroy, Victoria 3065, Australia. Department of Biochemistry and Molecular Biology and Bio21 Institute, University of Melbourne, Parkville, Victoria 3052, Australia
| | - Emma Sierecki
- The University of Queensland, Institute for Molecular Bioscience (IMB), St Lucia, Queensland 4072, Australia
| | - Yann Gambin
- The University of Queensland, Institute for Molecular Bioscience (IMB), St Lucia, Queensland 4072, Australia
| | - Guillermo A Gomez
- The University of Queensland, Institute for Molecular Bioscience (IMB), St Lucia, Queensland 4072, Australia
| | - Kirill Alexandrov
- The University of Queensland, Institute for Molecular Bioscience (IMB), St Lucia, Queensland 4072, Australia
| | - Ian A Wilson
- Scripps Research Institute, La Jolla, CA 92037, USA
| | - Manolis Doxastakis
- Department of Chemical and Biomolecular Engineering, University of Houston, Houston, TX 77004, USA
| | - Alan E Mark
- The University of Queensland, Institute for Molecular Bioscience (IMB), St Lucia, Queensland 4072, Australia. The University of Queensland, School of Chemistry and Molecular Biosciences, St Lucia, Queensland 4072, Australia
| | - Michael J Waters
- The University of Queensland, Institute for Molecular Bioscience (IMB), St Lucia, Queensland 4072, Australia.
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23
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Ahuja LG, Gopal B. Bi-domain protein tyrosine phosphatases reveal an evolutionary adaptation to optimize signal transduction. Antioxid Redox Signal 2014; 20:2141-59. [PMID: 24206235 DOI: 10.1089/ars.2013.5721] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
SIGNIFICANCE The bi-domain protein tyrosine phosphatases (PTPs) exemplify functional evolution in signaling proteins for optimal spatiotemporal signal transduction. Bi-domain PTPs are products of gene duplication. The catalytic activity, however, is often localized to one PTP domain. The inactive PTP domain adopts multiple functional roles. These include modulation of catalytic activity, substrate specificity, and stability of the bi-domain enzyme. In some cases, the inactive PTP domain is a receptor for redox stimuli. Since multiple bi-domain PTPs are concurrently active in related cellular pathways, a stringent regulatory mechanism and selective cross-talk is essential to ensure fidelity in signal transduction. RECENT ADVANCES The inactive PTP domain is an activator for the catalytic PTP domain in some cases, whereas it reduces catalytic activity in other bi-domain PTPs. The relative orientation of the two domains provides a conformational rationale for this regulatory mechanism. Recent structural and biochemical data reveal that these PTP domains participate in substrate recruitment. The inactive PTP domain has also been demonstrated to undergo substantial conformational rearrangement and oligomerization under oxidative stress. CRITICAL ISSUES AND FUTURE DIRECTIONS The role of the inactive PTP domain in coupling environmental stimuli with catalytic activity needs to be further examined. Another aspect that merits attention is the role of this domain in substrate recruitment. These aspects have been poorly characterized in vivo. These lacunae currently restrict our understanding of neo-functionalization of the inactive PTP domain in the bi-domain enzyme. It appears likely that more data from these research themes could form the basis for understanding the fidelity in intracellular signal transduction.
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Affiliation(s)
- Lalima Gagan Ahuja
- 1 Molecular Biophysics Unit, Indian Institute of Science , Bangalore, India
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24
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Finkelshtein E, Lotinun S, Levy-Apter E, Arman E, den Hertog J, Baron R, Elson A. Protein tyrosine phosphatases ε and α perform nonredundant roles in osteoclasts. Mol Biol Cell 2014; 25:1808-18. [PMID: 24694598 PMCID: PMC4038506 DOI: 10.1091/mbc.e14-03-0788] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
The closely related tyrosine phosphatases PTPa and PTPe fulfill distinct roles in osteoclasts. The various effects of each PTP on podosome organization in osteoclasts are caused by their distinct N-termini. The function of PTPe in these cells requires the presence of its 12 N-terminal residues, in particular serine 2. Female mice lacking protein tyrosine phosphatase ε (PTP ε) are mildly osteopetrotic. Osteoclasts from these mice resorb bone matrix poorly, and the structure, stability, and cellular organization of their podosomal adhesion structures are abnormal. Here we compare the role of PTP ε with that of the closely related PTP α in osteoclasts. We show that bone mass and bone production and resorption, as well as production, structure, function, and podosome organization of osteoclasts, are unchanged in mice lacking PTP α. The varying effects of either PTP on podosome organization in osteoclasts are caused by their distinct N-termini. Osteoclasts express the receptor-type PTP α (RPTPa), which is absent from podosomes, and the nonreceptor form of PTP ε (cyt-PTPe), which is present in these structures. The presence of the unique 12 N-terminal residues of cyt-PTPe is essential for podosome regulation; attaching this sequence to the catalytic domains of PTP α enables them to function in osteoclasts. Serine 2 within this sequence regulates cyt-PTPe activity and its effects on podosomes. We conclude that PTPs α and ε play distinct roles in osteoclasts and that the N-terminus of cyt-PTPe, in particular serine 2, is critical for its function in these cells.
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Affiliation(s)
- Eynat Finkelshtein
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Sutada Lotinun
- Department of Oral Medicine, Infection and Immunity, Harvard School of Dental Medicine, Boston, MA 02115
| | - Einat Levy-Apter
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Esther Arman
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Jeroen den Hertog
- Hubrecht Institute-Koninklijke Nederlandse Akademie van Wetenschappen and University Medical Center Utrecht, 3584 CX Utrecht, NetherlandsInstitute of Biology Leiden, Leiden University, 2333 BE Leiden, Netherlands
| | - Roland Baron
- Department of Oral Medicine, Infection and Immunity, Harvard School of Dental Medicine, Boston, MA 02115
| | - Ari Elson
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
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25
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Lee H, Bennett AM. Receptor protein tyrosine phosphatase-receptor tyrosine kinase substrate screen identifies EphA2 as a target for LAR in cell migration. Mol Cell Biol 2013; 33:1430-41. [PMID: 23358419 PMCID: PMC3624262 DOI: 10.1128/mcb.01708-12] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2012] [Accepted: 01/23/2013] [Indexed: 01/08/2023] Open
Abstract
Receptor tyrosine kinases (RTKs) exist in equilibrium between tyrosyl-phosphorylated and dephosphorylated states. Despite a detailed understanding of how RTKs become tyrosyl phosphorylated, much less is known about RTK tyrosyl dephosphorylation. Receptor protein tyrosine phosphatases (RPTPs) can play essential roles in the dephosphorylation of RTKs. However, a complete understanding of the involvement of the RPTP subfamily in RTK tyrosyl dephosphorylation has not been established. In this study, we have employed a small interfering RNA (siRNA) screen to identify RPTPs in the human genome that serve as RTK phosphatases. We observed that each RPTP induced a unique fingerprint of tyrosyl phosphorylation among 42 RTKs. We identified EphA2 as a novel LAR substrate. LAR dephosphorylated EphA2 at phosphotyrosyl 930, uncoupling Nck1 from EphA2 and thereby attenuating EphA2-mediated cell migration. These results demonstrate that each RPTP exerts a unique regulatory fingerprint of RTK tyrosyl dephosphorylation and suggest a complex signaling interplay between RTKs and RPTPs. Furthermore, we observed that LAR modulates cell migration through EphA2 site-specific dephosphorylation.
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Affiliation(s)
| | - Anton M. Bennett
- Department of Pharmacology
- Program in Integrative Cell Signaling and Neurobiology of Metabolism, Yale University School of Medicine, New Haven, Connecticut, USA
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26
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Böhmer F, Szedlacsek S, Tabernero L, Ostman A, den Hertog J. Protein tyrosine phosphatase structure-function relationships in regulation and pathogenesis. FEBS J 2013; 280:413-31. [PMID: 22682070 DOI: 10.1111/j.1742-4658.2012.08655.x] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Protein phosphorylation on tyrosine residues is tightly controlled by protein tyrosine phosphatases (PTPs) at multiple levels: spatio-temporal expression, subcellular localization and post-translational modification. Structural and functional analysis of the PTP domains has provided insight into catalysis and regulatory mechanisms that control the enzymatic activity. Understanding the molecular basis of PTP regulation is of fundamental importance to dissect the pleiotropic effect of these enzymes in both health and disease. Here, we review recent insights into the regulation of receptor-like PTPs by extracellular ligands and into regulation by reversible oxidation that impairs catalysis directly. The physiological roles of PTPs are essential in homeostasis in eukaryotic cells and pertubation of their functional attributes causes different disease states. As an example, we discuss recent findings indicating how inappropriate oxidation of PTPs in cancer cells may contribute to cell transformation. On the other hand, PTPs from many pathogens are key virulence factors and manipulate signalling pathways in the host cells to promote invasion and survival of the microorganisms. This research area has received relatively little attention but has advanced remarkably. We review the structural features of pathogenic PTPs, their similarities and differences with eukaryotic PTPs, and the possible exploitation of this knowledge for therapeutic intervention.
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Affiliation(s)
- Frank Böhmer
- Center for Molecular Biomedicine, Jena University Hospital, Jena, Germany
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27
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Receptor type protein tyrosine phosphatases (RPTPs) - roles in signal transduction and human disease. J Cell Commun Signal 2012; 6:125-38. [PMID: 22851429 DOI: 10.1007/s12079-012-0171-5] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2012] [Accepted: 07/12/2012] [Indexed: 01/06/2023] Open
Abstract
Protein tyrosine phosphorylation is a fundamental regulatory mechanism controlling cell proliferation, differentiation, communication, and adhesion. Disruption of this key regulatory mechanism contributes to a variety of human diseases including cancer, diabetes, and auto-immune diseases. Net protein tyrosine phosphorylation is determined by the dynamic balance of the activity of protein tyrosine kinases (PTKs) and protein tyrosine phosphatases (PTPs). Mammals express many distinct PTKs and PTPs. Both of these families can be sub-divided into non-receptor and receptor subtypes. Receptor protein tyrosine kinases (RPTKs) comprise a large family of cell surface proteins that initiate intracellular tyrosine phosphorylation-dependent signal transduction in response to binding of extracellular ligands, such as growth factors and cytokines. Receptor-type protein tyrosine phosphatases (RPTPs) are enzymatic and functional counterparts of RPTKs. RPTPs are a family of integral cell surface proteins that possess intracellular PTP activity, and extracellular domains that have sequence homology to cell adhesion molecules. In comparison to extensively studied RPTKs, much less is known about RPTPs, especially regarding their substrate specificities, regulatory mechanisms, biological functions, and their roles in human diseases. Based on the structure of their extracellular domains, the RPTP family can be grouped into eight sub-families. This article will review one representative member from each RPTP sub-family.
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Roca-Cusachs P, Iskratsch T, Sheetz MP. Finding the weakest link: exploring integrin-mediated mechanical molecular pathways. J Cell Sci 2012; 125:3025-38. [PMID: 22797926 DOI: 10.1242/jcs.095794] [Citation(s) in RCA: 176] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
From the extracellular matrix to the cytoskeleton, a network of molecular links connects cells to their environment. Molecules in this network transmit and detect mechanical forces, which subsequently determine cell behavior and fate. Here, we reconstruct the mechanical pathway followed by these forces. From matrix proteins to actin through integrins and adaptor proteins, we review how forces affect the lifetime of bonds and stretch or alter the conformation of proteins, and how these mechanical changes are converted into biochemical signals in mechanotransduction events. We evaluate which of the proteins in the network can participate in mechanotransduction and which are simply responsible for transmitting forces in a dynamic network. Besides their individual properties, we also analyze how the mechanical responses of a protein are determined by their serial connections from the matrix to actin, their parallel connections in integrin clusters and by the rate at which force is applied to them. All these define mechanical molecular pathways in cells, which are emerging as key regulators of cell function alongside better studied biochemical pathways.
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Affiliation(s)
- Pere Roca-Cusachs
- University of Barcelona and Institute for Bioengineering of Catalonia, Barcelona, Spain.
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Huang J, Yao L, Xu R, Wu H, Wang M, White BS, Shalloway D, Zheng X. Activation of Src and transformation by an RPTPα splice mutant found in human tumours. EMBO J 2011; 30:3200-11. [PMID: 21725282 DOI: 10.1038/emboj.2011.212] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2010] [Accepted: 06/07/2011] [Indexed: 11/09/2022] Open
Abstract
Receptor protein tyrosine phosphatase α (RPTPα)-mediated Src activation is required for survival of tested human colon and oestrogen receptor-negative breast cancer cell lines. To explore whether mutated RPTPα participates in human carcinogenesis, we sequenced RPTPα cDNAs from five types of human tumours and found splice mutants in ∼30% of colon, breast, and liver tumours. RPTPα245, a mutant expressed in all three tumour types, was studied further. Although it lacks any catalytic domain, RPTPα245 expression in the tumours correlated with Src tyrosine dephosphorylation, and its expression in rodent fibroblasts activated Src by a novel mechanism. This involved RPTPα245 binding to endogenous RPTPα (eRPTPα), which decreased eRPTPα-Grb2 binding and increased eRPTPα dephosphorylation of Src without increasing non-specific eRPTPα activity. RPTPα245-eRPTPα binding was blocked by Pro210 → Leu/Pro211 → Leu mutation, consistent with the involvement of the structural 'wedge' that contributes to eRPTPα homodimerization. RPTPα245-induced fibroblast transformation was blocked by either Src or eRPTPα RNAi, indicating that this required the dephosphorylation of Src by eRPTPα. The transformed cells were tumourigenic in nude mice, suggesting that RPTPα245-induced activation of Src in the human tumours may have contributed to carcinogenesis.
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Affiliation(s)
- Jian Huang
- Department of Biochemistry and Molecular Biology, Shanghai JiaoTong University School of Medicine, Shanghai, PR China
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30
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Ren L, Chen X, Luechapanichkul R, Selner NG, Meyer TM, Wavreille AS, Chan R, Iorio C, Zhou X, Neel BG, Pei D. Substrate specificity of protein tyrosine phosphatases 1B, RPTPα, SHP-1, and SHP-2. Biochemistry 2011; 50:2339-56. [PMID: 21291263 DOI: 10.1021/bi1014453] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
We determined the substrate specificities of the protein tyrosine phosphatases (PTPs) PTP1B, RPTPα, SHP-1, and SHP-2 by on-bead screening of combinatorial peptide libraries and solution-phase kinetic analysis of individually synthesized phosphotyrosyl (pY) peptides. These PTPs exhibit different levels of sequence specificity and catalytic efficiency. The catalytic domain of RPTPα has very weak sequence specificity and is approximately 2 orders of magnitude less active than the other three PTPs. The PTP1B catalytic domain has modest preference for acidic residues on both sides of pY, is highly active toward multiply phosphorylated peptides, but disfavors basic residues at any position, a Gly at the pY-1 position, or a Pro at the pY+1 position. By contrast, SHP-1 and SHP-2 share similar but much narrower substrate specificities, with a strong preference for acidic and aromatic hydrophobic amino acids on both sides of the pY residue. An efficient SHP-1/2 substrate generally contains two or more acidic residues on the N-terminal side and one or more acidic residues on the C-terminal side of pY but no basic residues. Subtle differences exist between SHP-1 and SHP-2 in that SHP-1 has a stronger preference for acidic residues at the pY-1 and pY+1 positions and the two SHPs prefer acidic residues at different positions N-terminal to pY. A survey of the known protein substrates of PTP1B, SHP-1, and SHP-2 shows an excellent agreement between the in vivo dephosphorylation pattern and the in vitro specificity profiles derived from library screening. These results suggest that different PTPs have distinct sequence specificity profiles and the intrinsic activity/specificity of the PTP domain is an important determinant of the enzyme's in vivo substrate specificity.
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Affiliation(s)
- Lige Ren
- Department of Chemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, United States
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31
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Deb I, Poddar R, Paul S. Oxidative stress-induced oligomerization inhibits the activity of the non-receptor tyrosine phosphatase STEP61. J Neurochem 2011; 116:1097-111. [PMID: 21198639 DOI: 10.1111/j.1471-4159.2010.07165.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The neuron-specific tyrosine phosphatase STriatal Enriched Phosphatase (STEP) is emerging as an important mediator of glutamatergic transmission in the brain. STEP is also thought to be involved in the etiology of neurodegenerative disorders that are linked to oxidative stress such as Alzheimer's disease and cerebral ischemia. However, the mechanism by which oxidative stress can modulate STEP activity is still unclear. In this study, we have investigated whether dimerization may play a role in regulating the activity of STEP. Our findings show that STEP(61), the membrane associated isoform, can undergo homodimerization under basal conditions in neurons. Dimerization of STEP(61) involves intermolecular disulfide bond formation between two cysteine residues (Cys 65 and Cys 76 respectively) present in the hydrophobic region at the N-terminus specific to STEP(61). Oxidative stress induced by hydrogen peroxide leads to a significant increase in the formation of dimers and higher-order oligomers of STEP(61). Using two substrates, para-nitrophenylphosphate and extracellular-regulated kinase MAPK we further demonstrate that oligomerization leads to a significant reduction in its enzymatic activity.
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Affiliation(s)
- Ishani Deb
- Department of Neurology, University of New Mexico Health Sciences Center, 1 University of New Mexico, Albuquerque, New Mexico 87131, USA
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32
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Moore SW, Roca-Cusachs P, Sheetz MP. Stretchy proteins on stretchy substrates: the important elements of integrin-mediated rigidity sensing. Dev Cell 2010; 19:194-206. [PMID: 20708583 DOI: 10.1016/j.devcel.2010.07.018] [Citation(s) in RCA: 304] [Impact Index Per Article: 21.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2010] [Revised: 06/13/2010] [Accepted: 07/16/2010] [Indexed: 01/06/2023]
Abstract
Matrix and tissue rigidity guides many cellular processes, including the differentiation of stem cells and the migration of cells in health and disease. Cells actively and transiently test rigidity using mechanisms limited by inherent physical parameters that include the strength of extracellular attachments, the pulling capacity on these attachments, and the sensitivity of the mechanotransduction system. Here, we focus on rigidity sensing mediated through the integrin family of extracellular matrix receptors and linked proteins and discuss the evidence supporting these proteins as mechanosensors.
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Affiliation(s)
- Simon W Moore
- Department of Biological Sciences, Columbia University, New York, NY 10027, USA
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33
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Serine dephosphorylation of receptor protein tyrosine phosphatase alpha in mitosis induces Src binding and activation. Mol Cell Biol 2010; 30:2850-61. [PMID: 20385765 DOI: 10.1128/mcb.01202-09] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Receptor protein tyrosine phosphatase alpha (RPTPalpha) is the mitotic activator of the protein tyrosine kinase Src. RPTPalpha serine hyperphosphorylation was proposed to mediate mitotic activation of Src. We raised phosphospecific antibodies to the two main serine phosphorylation sites, and we discovered that RPTPalpha Ser204 was almost completely dephosphorylated in mitotic NIH 3T3 and HeLa cells, whereas Ser180 and Tyr789 phosphorylation were only marginally reduced in mitosis. Concomitantly, Src pTyr527 and pTyr416 were dephosphorylated, resulting in 2.3-fold activation of Src in mitosis. Using inhibitors and knockdown experiments, we demonstrated that dephosphorylation of RPTPalpha pSer204 in mitosis was mediated by PP2A. Mutation of Ser204 to Ala did not activate RPTPalpha, and intrinsic catalytic activity of RPTPalpha was not affected in mitosis. Interestingly, binding of endogenous Src to RPTPalpha was induced in mitosis. GRB2 binding to RPTPalpha, which was proposed to compete with Src binding to RPTPalpha, was only modestly reduced in mitosis, which could not account for enhanced Src binding. Moreover, we demonstrate that Src bound to mutant RPTPalpha-Y789F, lacking the GRB2 binding site, and mutant Src with an impaired Src homology 2 (SH2) domain bound to RPTPalpha, illustrating that Src binding to RPTPalpha is not mediated by a pTyr-SH2 interaction. Mutation of RPTPalpha Ser204 to Asp, mimicking phosphorylation, reduced coimmunoprecipitation with Src, suggesting that phosphorylation of Ser204 prohibits binding to Src. Based on our results, we propose a new model for mitotic activation of Src in which PP2A-mediated dephosphorylation of RPTPalpha pSer204 facilitates Src binding, leading to RPTPalpha-mediated dephosphorylation of Src pTyr527 and pTyr416 and hence modest activation of Src.
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34
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Hsu MJ, Sheu JR, Lin CH, Shen MY, Hsu CY. Mitochondrial mechanisms in amyloid beta peptide-induced cerebrovascular degeneration. Biochim Biophys Acta Gen Subj 2010; 1800:290-6. [DOI: 10.1016/j.bbagen.2009.08.003] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2009] [Revised: 08/06/2009] [Accepted: 08/11/2009] [Indexed: 01/19/2023]
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35
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Vacaru AM, den Hertog J. Catalytically active membrane-distal phosphatase domain of receptor protein-tyrosine phosphatase alpha is required for Src activation. FEBS J 2010; 277:1562-70. [PMID: 20158519 DOI: 10.1111/j.1742-4658.2010.07584.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Receptor protein-tyrosine phosphatase alpha (RPTPalpha) is a transmembrane protein with tandem cytoplasmic phosphatase domains. Most of the catalytic activity is contained by the membrane-proximal catalytic domain (D1). We found a spontaneous Arg554 to His mutation in the pTyr recognition loop of the membrane-distal phosphatase domain (D2) of a human patient. This mutation was not linked to the disease. Here, we report that the R554H mutation abolished RPTPalpha-D2 catalytic activity. The R554H mutation impaired Src binding to RPTPalpha. RPTPalpha, with a catalytic site cysteine to serine mutation in D2, also displayed diminished binding to Src. Concomitant with decreased Src binding of the R554H and C723S mutants compared with wild-type RPTPalpha, enhanced phosphorylation of the inhibitory Src Tyr527 site was observed, as well as reduced Src activation. To confirm that catalytic activity of RPTPalpha-D2 was required for these effects, we analyzed a third mutant, RPTPalpha-R729K, which had an inactive D2. Again, Src binding was reduced and Tyr527 phosphorylation was enhanced. Our results suggest that a catalytically active D2 is required for RPTPalpha to bind and dephosphorylate its well-characterized substrate, Src.
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Affiliation(s)
- Andrei M Vacaru
- Hubrecht Institute - KNAW and University Medical Center, Utrecht, the Netherlands
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36
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The receptor protein tyrosine phosphatase LAR promotes R7 photoreceptor axon targeting by a phosphatase-independent signaling mechanism. Proc Natl Acad Sci U S A 2009; 106:19399-404. [PMID: 19889974 DOI: 10.1073/pnas.0903961106] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Receptor protein tyrosine phosphatases (RPTPs) control many aspects of nervous system development. At the Drosophila neuromuscular junction (NMJ), regulation of synapse growth and maturation by the RPTP LAR depends on catalytic phosphatase activity and on the extracellular ligands Syndecan and Dally-like. We show here that the function of LAR in controlling R7 photoreceptor axon targeting in the visual system differs in several respects. The extracellular domain of LAR important for this process is distinct from the domains known to bind Syndecan and Dally-like, suggesting the involvement of a different ligand. R7 targeting does not require LAR phosphatase activity, but instead depends on the phosphatase activity of another RPTP, PTP69D. In addition, a mutation that prevents dimerization of the intracellular domain of LAR interferes with its ability to promote R7 targeting, although it does not disrupt phosphatase activity or neuromuscular synapse growth. We propose that LAR function in R7 is independent of its phosphatase activity, but requires structural features that allow dimerization and may promote the assembly of downstream effectors.
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37
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Hower AE, Beltran PJ, Bixby JL. Dimerization of tyrosine phosphatase PTPRO decreases its activity and ability to inactivate TrkC. J Neurochem 2009; 110:1635-47. [PMID: 19573017 DOI: 10.1111/j.1471-4159.2009.06261.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Receptor-protein tyrosine phosphatases (RPTPs), like receptor tyrosine kinases, regulate neuronal differentiation. While receptor tyrosine kinases are dimerized and activated by extracellular ligands, the extent to which RPTPs dimerize, and the effects of dimerization on phosphatase activity, are poorly understood. We have examined a neuronal type III RPTP, PTPRO; we find that PTPRO can form dimers in living cells, and that disulfide linkages in PTPROs intracellular domain likely regulate dimerization. Dimerization of PTPROs transmembrane and intracellular domains, achieved by ligand binding to a chimeric fusion protein, decreases activity toward artificial peptides and toward a putative substrate, tropomyosin-related kinase C (TrkC). Dephosphorylation of TrkC by PTPRO may be physiologically relevant, as it is efficient, and TrkC and PTPRO can be co-precipitated from transfected cells. Inhibition of PTPROs phosphatase activity by dimerization is interesting, as dimerization of a related RPTP, CD148/PTPRJ, increases activity. Thus, our results suggest a complex relationship between dimerization and activity in type III RPTPs.
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38
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Tang ED, Wang CY. MAVS self-association mediates antiviral innate immune signaling. J Virol 2009; 83:3420-8. [PMID: 19193783 PMCID: PMC2663242 DOI: 10.1128/jvi.02623-08] [Citation(s) in RCA: 109] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2008] [Accepted: 01/28/2009] [Indexed: 01/12/2023] Open
Abstract
The innate immune system recognizes nucleic acids during viral infection and stimulates cellular antiviral responses. Intracellular detection of RNA virus infection is mediated by the RNA helicases RIG-I (retinoic acid inducible gene I) and MDA-5, which recognize viral RNA and signal through the adaptor molecule MAVS (mitochondrial antiviral signaling) to stimulate the phosphorylation and activation of the transcription factors IRF3 (interferon regulatory factor 3) and IRF7. Once activated, IRF3 and IRF7 turn on the expression of type I interferons, such as beta interferon. Interestingly, unlike other signaling molecules identified in this pathway, MAVS contains a C-terminal transmembrane (TM) domain that is essential for both type I interferon induction and localization of MAVS to the mitochondrial outer membrane. However, the role the MAVS TM domain plays in signaling remains unclear. Here we report the identification of a function for the TM domain in mediating MAVS self-association. The activation of RIG-I/MDA-5 leads to the TM-dependent dimerization of the MAVS N-terminal caspase recruitment domain, thereby providing an interface for direct binding to and activation of the downstream effector TRAF3 (tumor necrosis factor receptor-associated factor 3). Our results reveal a role for MAVS self-association in antiviral innate immunity signaling and provide a molecular mechanism for downstream signal transduction.
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Affiliation(s)
- Eric D Tang
- Laboratory of Molecular Signaling, Division of Oral Biology and Medicine, UCLA School of Dentistry, Los Angeles, California 90095, USA
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39
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Barr AJ, Ugochukwu E, Lee WH, King ON, Filippakopoulos P, Alfano I, Savitsky P, Burgess-Brown NA, Müller S, Knapp S. Large-scale structural analysis of the classical human protein tyrosine phosphatome. Cell 2009; 136:352-63. [PMID: 19167335 PMCID: PMC2638020 DOI: 10.1016/j.cell.2008.11.038] [Citation(s) in RCA: 358] [Impact Index Per Article: 23.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2008] [Revised: 09/15/2008] [Accepted: 11/20/2008] [Indexed: 02/05/2023]
Abstract
Protein tyrosine phosphatases (PTPs) play a critical role in regulating cellular functions by selectively dephosphorylating their substrates. Here we present 22 human PTP crystal structures that, together with prior structural knowledge, enable a comprehensive analysis of the classical PTP family. Despite their largely conserved fold, surface properties of PTPs are strikingly diverse. A potential secondary substrate-binding pocket is frequently found in phosphatases, and this has implications for both substrate recognition and development of selective inhibitors. Structural comparison identified four diverse catalytic loop (WPD) conformations and suggested a mechanism for loop closure. Enzymatic assays revealed vast differences in PTP catalytic activity and identified PTPD1, PTPD2, and HDPTP as catalytically inert protein phosphatases. We propose a “head-to-toe” dimerization model for RPTPγ/ζ that is distinct from the “inhibitory wedge” model and that provides a molecular basis for inhibitory regulation. This phosphatome resource gives an expanded insight into intrafamily PTP diversity, catalytic activity, substrate recognition, and autoregulatory self-association.
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Affiliation(s)
- Alastair J. Barr
- University of Oxford, Structural Genomics Consortium, Old Road Campus Research Building, Roosevelt Drive, Headington, Oxford, OX3 7DQ, UK
- Corresponding author
| | - Emilie Ugochukwu
- University of Oxford, Structural Genomics Consortium, Old Road Campus Research Building, Roosevelt Drive, Headington, Oxford, OX3 7DQ, UK
| | - Wen Hwa Lee
- University of Oxford, Structural Genomics Consortium, Old Road Campus Research Building, Roosevelt Drive, Headington, Oxford, OX3 7DQ, UK
| | - Oliver N.F. King
- University of Oxford, Structural Genomics Consortium, Old Road Campus Research Building, Roosevelt Drive, Headington, Oxford, OX3 7DQ, UK
| | - Panagis Filippakopoulos
- University of Oxford, Structural Genomics Consortium, Old Road Campus Research Building, Roosevelt Drive, Headington, Oxford, OX3 7DQ, UK
| | - Ivan Alfano
- University of Oxford, Structural Genomics Consortium, Old Road Campus Research Building, Roosevelt Drive, Headington, Oxford, OX3 7DQ, UK
| | - Pavel Savitsky
- University of Oxford, Structural Genomics Consortium, Old Road Campus Research Building, Roosevelt Drive, Headington, Oxford, OX3 7DQ, UK
| | - Nicola A. Burgess-Brown
- University of Oxford, Structural Genomics Consortium, Old Road Campus Research Building, Roosevelt Drive, Headington, Oxford, OX3 7DQ, UK
| | - Susanne Müller
- University of Oxford, Structural Genomics Consortium, Old Road Campus Research Building, Roosevelt Drive, Headington, Oxford, OX3 7DQ, UK
| | - Stefan Knapp
- University of Oxford, Structural Genomics Consortium, Old Road Campus Research Building, Roosevelt Drive, Headington, Oxford, OX3 7DQ, UK
- University of Oxford, Department of Clinical Pharmacology, Old Road Campus, Roosevelt Drive, Oxford OX3 7DQ, UK
- Corresponding author
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Iuliano R, Raso C, Quintiero A, Pera IL, Pichiorri F, Palumbo T, Palmieri D, Pattarozzi A, Florio T, Viglietto G, Trapasso F, Croce CM, Fusco A. The eighth fibronectin type III domain of protein tyrosine phosphatase receptor J influences the formation of protein complexes and cell localization. J Biochem 2009; 145:377-85. [PMID: 19122201 DOI: 10.1093/jb/mvn175] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Regulation of receptor-type phosphatases can involve the formation of higher-order structures, but the exact role played in this process by protein domains is not well understood. In this study we show the formation of different higher-order structures of the receptor-type phosphatase PTPRJ, detected in HEK293A cells transfected with different PTPRJ expression constructs. In the plasma membrane PTPRJ forms dimers detectable by treatment with the cross-linking reagent BS(3) (bis[sulfosuccinimidyl]suberate). However, other PTPRJ complexes, dependent on the formation of disulfide bonds, are detected by treatment with the oxidant agent H(2)O(2) or by a mutation Asp872Cys, located in the eighth fibronectin type III domain of PTPRJ. A deletion in the eighth fibronectin domain of PTPRJ impairs its dimerization in the plasma membrane and increases the formation of PTPRJ complexes dependent on disulfide bonds that remain trapped in the cytoplasm. The deletion mutant maintains the catalytic activity but is unable to carry out inhibition of proliferation on HeLa cells, achieved by the wild type form, since it does not reach the plasma membrane. Therefore, the intact structure of the eighth fibronectin domain of PTPRJ is critical for its localization in plasma membrane and biological function.
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Affiliation(s)
- Rodolfo Iuliano
- Dipartimento di Medicina Sperimentale e Clinica, Facoltà di Medicina e Chirurgia, Università di Catanzaro, 88100 Catanzaro, Italy
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41
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Mark JK, Aubin RA, Smith S, Hefford MA. Inhibition of mitogen-activated protein kinase phosphatase 3 activity by interdomain binding. J Biol Chem 2008; 283:28574-83. [PMID: 18694935 DOI: 10.1074/jbc.m801747200] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Mitogen-activated protein (MAP) kinase phosphatase 3 (MKP3) is a cytoplasmic dual specificity phosphatase that functions to attenuate signaling via dephosphorylation and subsequent deactivation of its substrate and allosteric regulator, extracellular signal-regulated protein kinase 2 (ERK2). Expression of MKP3 has been shown to be under the control of ERK2, thus providing an elegant feedback mechanism for regulating the rate and duration of proliferative signals. Previously published studies suggest that MKP3 might serve as a tumor suppressor; however, significantly elevated, rather than reduced, levels of this protein have been reported in early lesions. Because overexpression of this phosphatase is counterintuitive to a proposed tumor suppressor function, the observed cellular tolerance suggested a self-inactivation mechanism. Using surface plasmon resonance, we have provided direct evidence of physical interaction between the N- and C-terminal domains. Kinetic analysis using dimethyl sulfoxide to activate the C-terminal fragment in the absence of ERK2 showed that the isolated C-terminal domain had higher catalytic efficiency than the similarly activated full-length protein. Furthermore, when the isolated N-terminal domain was added to the activated C-terminal domain, a dose-dependant inhibition of catalytic activity was observed. The similarity between the K(I) and K(D) values obtained indicate that interdomain binding stabilizes the inactive conformation of the catalytic site and implies that the N-terminal domain functions as an allosteric inhibitor of phosphatase activity. Finally, we have provided evidence for oligomerization of MKP3 in pancreatic cancer cells expressing elevated levels of this phosphatase.
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Affiliation(s)
- John K Mark
- Centre for Biologics Research, Health Canada, Ottawa, Ontario K1A 0L2, Canada
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42
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Rumfeldt JAO, Galvagnion C, Vassall KA, Meiering EM. Conformational stability and folding mechanisms of dimeric proteins. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2008; 98:61-84. [PMID: 18602415 DOI: 10.1016/j.pbiomolbio.2008.05.004] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
The folding of multisubunit proteins is of tremendous biological significance since the large majority of proteins exist as protein-protein complexes. Extensive experimental and computational studies have provided fundamental insights into the principles of folding of small monomeric proteins. Recently, important advances have been made in extending folding studies to multisubunit proteins, in particular homodimeric proteins. This review summarizes the equilibrium and kinetic theory and models underlying the quantitative analysis of dimeric protein folding using chemical denaturation, as well as the experimental results that have been obtained. Although various principles identified for monomer folding also apply to the folding of dimeric proteins, the effects of subunit association can manifest in complex ways, and are frequently overlooked. Changes in molecularity typically give rise to very different overall folding behaviour than is observed for monomeric proteins. The results obtained for dimers have provided key insights pertinent to understanding biological assembly and regulation of multisubunit proteins. These advances have set the stage for future advances in folding involving protein-protein interactions for natural multisubunit proteins and unnatural assemblies involved in disease.
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Affiliation(s)
- Jessica A O Rumfeldt
- Guelph-Waterloo Centre for Graduate Work in Chemistry and Biochemistry, Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
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43
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Groen A, Overvoorde J, van der Wijk T, den Hertog J. Redox regulation of dimerization of the receptor protein-tyrosine phosphatases RPTPα, LAR, RPTPμ and CD45. FEBS J 2008; 275:2597-604. [DOI: 10.1111/j.1742-4658.2008.06407.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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44
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Abstract
Protein-tyrosine phosphatases are tightly controlled by various mechanisms, ranging from differential expression in specific cell types to restricted subcellular localization, limited proteolysis, post-translational modifications affecting intrinsic catalytic activity, ligand binding and dimerization. Here, we review the regulatory mechanisms found to control the classical protein-tyrosine phosphatases.
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45
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Tabernero L, Aricescu AR, Jones EY, Szedlacsek SE. Protein tyrosine phosphatases: structure-function relationships. FEBS J 2008; 275:867-82. [PMID: 18298793 DOI: 10.1111/j.1742-4658.2008.06251.x] [Citation(s) in RCA: 109] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Structural analysis of protein tyrosine phosphatases (PTPs) has expanded considerably in the last several years, producing more than 200 structures in this class of enzymes (from 35 different proteins and their complexes with ligands). The small-medium size of the catalytic domain of approximately 280 residues plus a very compact fold makes it amenable to cloning and overexpression in bacterial systems thus facilitating crystallographic analysis. The low molecular weight PTPs being even smaller, approximately 150 residues, are also perfect targets for NMR analysis. The availability of different structures and complexes of PTPs with substrates and inhibitors has provided a wealth of information with profound effects in the way we understand their biological functions. Developments in mammalian expression technology recently led to the first crystal structure of a receptor-like PTP extracellular region. Altogether, the PTP structural work significantly advanced our knowledge regarding the architecture, regulation and substrate specificity of these enzymes. In this review, we compile the most prominent structural traits that characterize PTPs and their complexes with ligands. We discuss how the data can be used to design further functional experiments and as a basis for drug design given that many PTPs are now considered strategic therapeutic targets for human diseases such as diabetes and cancer.
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Granot-Attas S, Elson A. Protein tyrosine phosphatases in osteoclast differentiation, adhesion, and bone resorption. Eur J Cell Biol 2008; 87:479-90. [PMID: 18342392 DOI: 10.1016/j.ejcb.2008.01.006] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2007] [Revised: 01/16/2008] [Accepted: 01/16/2008] [Indexed: 01/06/2023] Open
Abstract
Osteoclasts are large cells derived from the monocyte-macrophage hematopoietic cell lineage. Their primary function is to degrade bone in various physiological contexts. Osteoclasts adhere to bone via podosomes, specialized adhesion structures whose structure and subcellular organization are affected by mechanical contact of the cell with bone matrix. Ample evidence indicates that reversible tyrosine phosphorylation of podosomal proteins plays a major role in determining the organization and dynamics of podosomes. Although roles of several tyrosine kinases are known in detail in this respect, little is known concerning the roles of protein tyrosine phosphatases (PTPs) in regulating osteoclast adhesion. Here we summarize available information concerning the known and hypothesized roles of the best-researched PTPs in osteoclasts - PTPRO, PTP epsilon, SHP-1, and PTP-PEST. Of these, PTPRO, PTP epsilon, and PTP-PEST appear to support osteoclast activity while SHP-1 inhibits it. Additional studies are required to provide full molecular details of the roles of these PTPs in regulating osteoclast adhesion, and to uncover additional PTPs that participate in this process.
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Affiliation(s)
- Shira Granot-Attas
- Department of Molecular Genetics, The Weizmann Institute of Science, Rehovot 76100, Israel
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Berman-Golan D, Granot-Attas S, Elson A. Protein tyrosine phosphatase epsilon and Neu-induced mammary tumorigenesis. Cancer Metastasis Rev 2008; 27:193-203. [DOI: 10.1007/s10555-008-9124-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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Kraut-Cohen J, Muller WJ, Elson A. Protein-tyrosine phosphatase epsilon regulates Shc signaling in a kinase-specific manner: increasing coherence in tyrosine phosphatase signaling. J Biol Chem 2007; 283:4612-21. [PMID: 18093973 DOI: 10.1074/jbc.m708822200] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Individual protein tyrosine kinases and phosphatases target multiple substrates; this may generate conflicting signals, possibly within a single pathway. Protein-tyrosine phosphatase epsilon (PTPepsilon) performs two potentially opposing roles: in Neu-induced mammary tumors, PTPepsilon activates Src downstream of Neu, whereas in other systems PTPepsilon can indirectly down-regulate MAP kinase signaling. We now show that the latter effect is mediated at least in part via the adaptor protein Shc. PTPepsilon binds and dephosphorylates Shc in vivo, reducing the association of Shc with Grb2 and inhibiting downstream ERK activation. PTPepsilon binds Shc in a phosphotyrosine-independent manner mediated by the Shc PTB domain and aided by a sequence of 10 N-terminal residues in PTPepsilon. Surprisingly, PTPepsilon dephosphorylates Shc in a kinase-dependent manner; PTPepsilon targets Shc in the presence of Src but not in the presence of Neu. Using a series of point mutants of Shc and Neu, we show that Neu protects Shc from dephosphorylation by binding the PTB domain of Shc, most likely competing against PTPepsilon for binding the same domain. In agreement, PTPepsilon dephosphorylates Shc in mouse embryo fibroblasts but not in Neu-induced mammary tumor cells. We conclude that in the context of Neu-induced mammary tumor cells, Neu prevents PTPepsilon from targeting Shc and from reducing its promitogenic signal while phosphorylating PTPepsilon and directing it to activate Src in support of mitogenesis. In so doing, Neu contributes to the coherence of the promitogenic role of PTPepsilon in this system.
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Affiliation(s)
- Judith Kraut-Cohen
- Department of Molecular Genetics, The Weizmann Institute of Science, Rehovot 76100, Israel
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Noordman YE, Augustus ED, Schepens JTG, Chirivi RGS, Ríos P, Pulido R, Hendriks WJAJ. Multimerisation of receptor-type protein tyrosine phosphatases PTPBR7 and PTP-SL attenuates enzymatic activity. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2007; 1783:275-86. [PMID: 18068678 DOI: 10.1016/j.bbamcr.2007.10.023] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2007] [Revised: 10/22/2007] [Accepted: 10/30/2007] [Indexed: 11/16/2022]
Abstract
Dimerisation of receptor-type protein tyrosine phosphatases (RPTPs) represents an appealing mechanism to regulate their enzymatic activity. Studies thus far mostly concern the dimerisation behaviour of RPTPs possessing two tandemly oriented catalytic PTP domains. Mouse gene Ptprr encodes four different protein isoforms (i.e. PTPBR7, PTP-SL and PTPPBSgamma-42/37) that contain a single PTP domain. Using selective membrane permeabilisation we here demonstrate that PTP-SL, like PTPBR7, is a single membrane-spanning RPTP. Furthermore, these two receptor-type PTPs constitutively formed homo- and hetero-meric complexes as witnessed in chemical cross-linking and co-immunoprecipitation experiments, in sharp contrast to the cytosolic PTPPBSgamma-42 and PTPPBSgamma-37 PTPRR isoforms. This multimerisation occurs independently of the PTP domain and requires the transmembrane domain and/or the proximal hydrophobic region. Using overexpression of a PTPBR7 mutant that essentially lacks the intracellular PTP domain-containing segment, a monomer-mimicking state was forced upon full-length PTPBR7 immunoprecipitates. This resulted in a significant increase in the enzymatic activity of the PTPRR PTP domain, which strengthens the notion that multimerisation represents a general mechanism to tone down RPTP catalytic activity.
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Affiliation(s)
- Yvet E Noordman
- Department of Cell Biology, Radboud University Nijmegen Medical Centre, Geert Grooteplein 28, 6525 GA Nijmegen, The Netherlands
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Faux C, Hawadle M, Nixon J, Wallace A, Lee S, Murray S, Stoker A. PTPσ binds and dephosphorylates neurotrophin receptors and can suppress NGF-dependent neurite outgrowth from sensory neurons. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2007; 1773:1689-700. [DOI: 10.1016/j.bbamcr.2007.06.008] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2007] [Revised: 06/22/2007] [Accepted: 06/25/2007] [Indexed: 12/25/2022]
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