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Matsui Y, Imai A, Izumi H, Yasumura M, Makino T, Shimizu T, Sato M, Mori H, Yoshida T. Cancer-associated point mutations within the extracellular domain of PTPRD affect protein stability and HSPG interaction. FASEB J 2024; 38:e23609. [PMID: 38593345 DOI: 10.1096/fj.202302279rr] [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: 11/05/2023] [Revised: 03/12/2024] [Accepted: 03/29/2024] [Indexed: 04/11/2024]
Abstract
PTPRD, a well-established tumor suppressor gene, encodes the protein tyrosine phosphatase-type D. This protein consists of three immunoglobulin-like (Ig) domains, four to eight fibronectin type 3 (FN) domains, a single transmembrane segment, and two cytoplasmic tandem tyrosine phosphatase domains. PTPRD is known to harbor various cancer-associated point mutations. While it is assumed that PTPRD regulates cellular functions as a tumor suppressor through the tyrosine phosphatase activity in the intracellular region, the function of its extracellular domain (ECD) in cancer is not well understood. In this study, we systematically examined the impact of 92 cancer-associated point mutations within the ECD. We found that 69.6% (64 out of 92) of these mutations suppressed total protein expression and/or plasma membrane localization. Notably, almost all mutations (20 out of 21) within the region between the last FN domain and transmembrane segment affected protein expression and/or localization, highlighting the importance of this region for protein stability. We further found that some mutations within the Ig domains adjacent to the glycosaminoglycan-binding pocket enhanced PTPRD's binding ability to heparan sulfate proteoglycans (HSPGs). This interaction is proposed to suppress phosphatase activity. Our findings therefore suggest that HSPG-mediated attenuation of phosphatase activity may be involved in tumorigenic processes through PTPRD dysregulation.
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Affiliation(s)
- Yu Matsui
- Department of Dermatology, Faculty of Medicine, University of Toyama, Toyama, Japan
| | - Ayako Imai
- Department of Molecular Neuroscience, Faculty of Medicine, University of Toyama, Toyama, Japan
- Research Center for Idling Brain Science, University of Toyama, Toyama, Japan
| | - Hironori Izumi
- Department of Molecular Neuroscience, Faculty of Medicine, University of Toyama, Toyama, Japan
- Research Center for Idling Brain Science, University of Toyama, Toyama, Japan
| | - Misato Yasumura
- Department of Anatomy and Neuroscience, Graduate School of Medicine, Osaka University, Osaka, Japan
- Division of Developmental Neuroscience, United Graduate School of Child Development (UGSCD), Osaka University, Osaka, Japan
| | - Teruhiko Makino
- Department of Dermatology, Faculty of Medicine, University of Toyama, Toyama, Japan
| | - Tadamichi Shimizu
- Department of Dermatology, Faculty of Medicine, University of Toyama, Toyama, Japan
| | - Makoto Sato
- Department of Anatomy and Neuroscience, Graduate School of Medicine, Osaka University, Osaka, Japan
- Division of Developmental Neuroscience, United Graduate School of Child Development (UGSCD), Osaka University, Osaka, Japan
| | - Hisashi Mori
- Department of Molecular Neuroscience, Faculty of Medicine, University of Toyama, Toyama, Japan
- Research Center for Idling Brain Science, University of Toyama, Toyama, Japan
| | - Tomoyuki Yoshida
- Department of Molecular Neuroscience, Faculty of Medicine, University of Toyama, Toyama, Japan
- Research Center for Idling Brain Science, University of Toyama, Toyama, Japan
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El Badaoui L, Barr AJ. Analysis of Receptor-Type Protein Tyrosine Phosphatase Extracellular Regions with Insights from AlphaFold. Int J Mol Sci 2024; 25:820. [PMID: 38255894 PMCID: PMC10815196 DOI: 10.3390/ijms25020820] [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: 11/16/2023] [Revised: 01/04/2024] [Accepted: 01/04/2024] [Indexed: 01/24/2024] Open
Abstract
The receptor-type protein tyrosine phosphatases (RPTPs) are involved in a wide variety of physiological functions which are mediated via their diverse extracellular regions. They play key roles in cell-cell contacts, bind various ligands and are regulated by dimerization and other processes. Depending on the subgroup, they have been described as everything from 'rigid rods' to 'floppy tentacles'. Here, we review current experimental structural knowledge on the extracellular region of RPTPs and draw on AlphaFold structural predictions to provide further insights into structure and function of these cellular signalling molecules, which are often mutated in disease and are recognised as drug targets. In agreement with experimental data, AlphaFold predicted structures for extracellular regions of R1, and R2B subgroup RPTPs have an extended conformation, whereas R2B RPTPs are twisted, reflecting their high flexibility. For the R3 PTPs, AlphaFold predicts that members of this subgroup adopt an extended conformation while others are twisted, and that certain members, such as CD148, have one or more large, disordered loop regions in place of fibronectin type 3 domains suggested by sequence analysis.
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Affiliation(s)
| | - Alastair J. Barr
- School of Life Sciences, University of Westminster, 115 New Cavendish Street, London W1W 6UW, UK;
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Tremblay ML. Advancing therapeutics using antibody-induced dimerization of receptor tyrosine phosphatases. Genes Dev 2023; 37:678-680. [PMID: 37673461 PMCID: PMC10546972 DOI: 10.1101/gad.351120.123] [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] [Indexed: 09/08/2023]
Abstract
Receptor protein tyrosine phosphatases (RPTPs) are involved in a broad list of cellular, developmental, and physiological functions. Altering their expression leads to significant changes in protein phosphorylation linked to a growing list of human diseases, including cancers and neurological disorders. In this issue of Genes & Development, Qian and colleagues (pp. 743-759) present the identification of a monoclonal antibody targeting PTPRD extracellular domain-inducing dimerization and inhibition of the phosphatase activities, causing the proteolysis of dimeric PTPRD by a mechanism involving intracellular degradation pathways. Their study supports the potential of modulating PTPRD via its extracellular domains. This opens a new framework in the clinical manipulation of PTPRD and its closely related family members.
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Affiliation(s)
- Michel L Tremblay
- Department of Biochemistry, Goodman Cancer Institute, Faculty of Medicine, McGill University, Montreal, Quebec H3A1A3, Canada
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