1
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Gude MF, Hjortebjerg R, Bjerre M, Pedersen AKN, Oxvig C, Rasmussen LM, Frystyk J, Steffensen L. The pro-atherogenic enzyme PAPP-A is active in eluates from human carotid and femoral atherosclerotic plaques. ATHEROSCLEROSIS PLUS 2024; 57:30-36. [PMID: 39308741 PMCID: PMC11415872 DOI: 10.1016/j.athplu.2024.09.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/17/2024] [Revised: 08/20/2024] [Accepted: 09/03/2024] [Indexed: 09/25/2024]
Abstract
Background Pregnancy-associated plasma protein-A (PAPP-A) regulates bioavailability of insulin-like growth factor 1 (IGF1) in various tissues by proteolytic cleavage of a subset of IGF-binding proteins (IGFBPs). Pre-clinical studies have established a role of PAPP-A in atherosclerosis and proposed that targeting the proteolytic activity of PAPP-A has therapeutic value.This study aimed to investigate whether human atherosclerotic plaques contain proteolytically active PAPP-A, a prerequisite for further considering PAPP-A as a therapeutic target in patients. Methods We obtained carotid (n = 9) and femoral (n = 11) atherosclerotic plaques from patients undergoing vascular surgery and incubated freshly harvested plaque tissue in culture media for 24 h. Subsequently, conditioned media were assayed for PAPP-A, STC2, IGFBP4, and IGF1 using immunoassays. Enzymatic activity of PAPP-A was assessed by its ability to process recombinant IGFBP4-IGF1 complexes - a specific substrate of PAPP-A - by Western blotting. Results PAPP-A and STC2 were detectable in conditioned media from both carotid and femoral plaques, with higher STC2 concentrations in eluates from carotid plaque incubations (p = 0.02). IGFBP4 and IGF1 were undetectable. Conditioned media from all 20 plaques exhibited PAPP-A proteolytic activity. However, no correlation between PAPP-A concentration and its proteolytic activity was observed, whereas the PAPP-A: STC2 molar ratio correlated with PAPP-A activity (R2 = 0.25, p = 0.03). Conclusion This study provides evidence for the presence of enzymatically active PAPP-A in atherosclerotic plaques and underscores the need for further investigating potential beneficial effects associated with targeting PAPP-A in atherosclerotic cardiovascular disease.
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Affiliation(s)
- Mette Faurholdt Gude
- Medical/Steno Aarhus Research Laboratory, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Rikke Hjortebjerg
- Endocrine Research Unit, Department of Endocrinology, Odense University Hospital, Odense, Denmark
- Department of Clinical Research, Faculty of Health Sciences, University of Southern Denmark, Odense, Denmark
- Steno Diabetes Center Odense, Odense University Hospital, Odense, Denmark
| | - Mette Bjerre
- Medical/Steno Aarhus Research Laboratory, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | | | - Claus Oxvig
- Dept. of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark
| | - Lars Melholt Rasmussen
- Centre for Individualized Medicine in Arterial Diseases (CIMA), Odense University Hospital, Odense, Denmark
- Dept. of Clinical Biochemistry, Odense University Hospital, Odense, Denmark
| | - Jan Frystyk
- Endocrine Research Unit, Department of Endocrinology, Odense University Hospital, Odense, Denmark
- Department of Clinical Research, Faculty of Health Sciences, University of Southern Denmark, Odense, Denmark
| | - Lasse Steffensen
- Dept. of Molecular Medicine, University of Southern Denmark, Odense, Denmark
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2
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Harboe M, Kjaer-Sorensen K, Füchtbauer EM, Fenton RA, Thomsen JS, Brüel A, Oxvig C. The metalloproteinase PAPP-A is required for IGF-dependent chondrocyte differentiation and organization. Sci Rep 2024; 14:20161. [PMID: 39215168 PMCID: PMC11364822 DOI: 10.1038/s41598-024-71062-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2024] [Accepted: 08/23/2024] [Indexed: 09/04/2024] Open
Abstract
Insulin-like growth factor (IGF) signaling is required for proper growth and skeletal development in vertebrates. Consequently, its dysregulation may lead to abnormalities of growth or skeletal structures. IGF is involved in the regulation of cell proliferation and differentiation of chondrocytes. However, the availability of bioactive IGF may be controlled by antagonizing IGF binding proteins (IGFBPs) in the circulation and tissues. As the metalloproteinase PAPP-A specifically cleaves members of the IGFBP family, we hypothesized that PAPP-A activity liberates bioactive IGF in cartilage. In PAPP-A knockout mice, the femur length was reduced and the mice showed a disorganized columnar organization of growth plate chondrocytes. Similarly, zebrafish lacking pappaa showed reduced length of Meckel's cartilage and disorganized chondrocytes, reminiscent of the mouse knockout phenotype. Expression of chondrocyte differentiation markers (sox9a, ihha, and col10a1) was markedly affected in Meckel's cartilage of pappaa knockout zebrafish, indicating that differentiation of chondrocytes was compromised. Additionally, the zebrafish pappaa knockout phenotype was mimicked by pharmacological inhibition of IGF signaling, and it could be rescued by treatment with exogenous recombinant IGF-I. In conclusion, our data suggests that IGF activity in the growing cartilage, and hence IGF signaling in chondrocytes, requires the presence of PAPP-A. The absence of PAPP-A causes aberrant chondrocyte organization and compromised growth in both mice and zebrafish.
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Affiliation(s)
- Mette Harboe
- Department of Molecular Biology and Genetics, Aarhus University, Universitetsbyen 81, 8000, Aarhus C, Denmark
| | - Kasper Kjaer-Sorensen
- Department of Molecular Biology and Genetics, Aarhus University, Universitetsbyen 81, 8000, Aarhus C, Denmark
| | - Ernst-Martin Füchtbauer
- Department of Molecular Biology and Genetics, Aarhus University, Universitetsbyen 81, 8000, Aarhus C, Denmark
| | - Robert A Fenton
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | | | - Annemarie Brüel
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | - Claus Oxvig
- Department of Molecular Biology and Genetics, Aarhus University, Universitetsbyen 81, 8000, Aarhus C, Denmark.
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3
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Poddar A, Ahmady F, Rao SR, Sharma R, Kannourakis G, Prithviraj P, Jayachandran A. The role of pregnancy associated plasma protein-A in triple negative breast cancer: a promising target for achieving clinical benefits. J Biomed Sci 2024; 31:23. [PMID: 38395880 PMCID: PMC10885503 DOI: 10.1186/s12929-024-01012-x] [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: 07/20/2023] [Accepted: 02/10/2024] [Indexed: 02/25/2024] Open
Abstract
Pregnancy associated plasma protein-A (PAPP-A) plays an integral role in breast cancer (BC), especially triple negative breast cancer (TNBC). This subtype accounts for the most aggressive BC, possesses high tumor heterogeneity, is least responsive to standard treatments and has the poorest clinical outcomes. There is a critical need to address the lack of effective targeted therapeutic options available. PAPP-A is a protein that is highly elevated during pregnancy. Frequently, higher PAPP-A expression is detected in tumors than in healthy tissues. The increase in expression coincides with increased rates of aggressive cancers. In BC, PAPP-A has been demonstrated to play a role in tumor initiation, progression, metastasis including epithelial-mesenchymal transition (EMT), as well as acting as a biomarker for predicting patient outcomes. In this review, we present the role of PAPP-A, with specific focus on TNBC. The structure and function of PAPP-A, belonging to the pappalysin subfamily, and its proteolytic activity are assessed. We highlight the link of BC and PAPP-A with respect to the IGFBP/IGF axis, EMT, the window of susceptibility and the impact of pregnancy. Importantly, the relevance of PAPP-A as a TNBC clinical marker is reviewed and its influence on immune-related pathways are explored. The relationship and mechanisms involving PAPP-A reveal the potential for more treatment options that can lead to successful immunotherapeutic targets and the ability to assist with better predicting clinical outcomes in TNBC.
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Affiliation(s)
- Arpita Poddar
- Fiona Elsey Cancer Research Institute, Victoria, Australia
- Federation University, Victoria, Australia
- RMIT University, Victoria, Australia
| | - Farah Ahmady
- Fiona Elsey Cancer Research Institute, Victoria, Australia
- Federation University, Victoria, Australia
| | - Sushma R Rao
- Fiona Elsey Cancer Research Institute, Victoria, Australia
- Adelaide Medical School, University of Adelaide, Adelaide, South Australia, Australia
| | - Revati Sharma
- Fiona Elsey Cancer Research Institute, Victoria, Australia
- Federation University, Victoria, Australia
| | - George Kannourakis
- Fiona Elsey Cancer Research Institute, Victoria, Australia
- Federation University, Victoria, Australia
| | - Prashanth Prithviraj
- Fiona Elsey Cancer Research Institute, Victoria, Australia
- Federation University, Victoria, Australia
| | - Aparna Jayachandran
- Fiona Elsey Cancer Research Institute, Victoria, Australia.
- Federation University, Victoria, Australia.
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4
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Conover CA, Oxvig C. The Pregnancy-Associated Plasma Protein-A (PAPP-A) Story. Endocr Rev 2023; 44:1012-1028. [PMID: 37267421 DOI: 10.1210/endrev/bnad017] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/10/2023] [Revised: 05/01/2023] [Accepted: 05/31/2023] [Indexed: 06/04/2023]
Abstract
Pregnancy-associated plasma protein-A (PAPP-A) was first identified in the early 1970s as a placental protein of unknown function, present at high concentrations in the circulation of pregnant women. In the mid-to-late 1990s, PAPP-A was discovered to be a metzincin metalloproteinase, expressed by many nonplacental cells, that regulates local insulin-like growth factor (IGF) activity through cleavage of high-affinity IGF binding proteins (IGFBPs), in particular IGFBP-4. With PAPP-A as a cell surface-associated enzyme, the reduced affinity of the cleavage fragments results in increased IGF available to bind and activate IGF receptors in the pericellular environment. This proteolytic regulation of IGF activity is important, since the IGFs promote proliferation, differentiation, migration, and survival in various normal and cancer cells. Thus, there has been a steady growth in investigation of PAPP-A structure and function outside of pregnancy. This review provides historical perspective on the discovery of PAPP-A and its structure and cellular function, highlights key studies of the first 50 years in PAPP-A research, and introduces new findings from recent years.
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Affiliation(s)
- Cheryl A Conover
- Division of Endocrinology, Mayo Clinic, Rochester, MN 55905, USA
| | - Claus Oxvig
- Department of Molecular Biology and Genetics, Aarhus University, 8000 Aarhus, Denmark
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5
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Sridar J, Mafi A, Judge RA, Xu J, Kong KA, Wang JCK, Stoll VS, Koukos G, Simon RJ, Eaton D, Bratkowski M, Hao Q. Cryo-EM structure of human PAPP-A2 and mechanism of substrate recognition. Commun Chem 2023; 6:234. [PMID: 37898658 PMCID: PMC10613257 DOI: 10.1038/s42004-023-01032-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Accepted: 10/18/2023] [Indexed: 10/30/2023] Open
Abstract
Pregnancy-Associated Plasma Protein A isoforms, PAPP-A and PAPP-A2, are metalloproteases that cleave insulin-like growth factor binding proteins (IGFBPs) to modulate insulin-like growth factor signaling. The structures of homodimeric PAPP-A in complex with IGFBP5 anchor peptide, and inhibitor proteins STC2 and proMBP have been recently reported. Here, we present the single-particle cryo-EM structure of the monomeric, N-terminal LG, MP, and the M1 domains (with the exception of LNR1/2) of human PAPP-A2 to 3.13 Å resolution. Our structure together with functional studies provides insight into a previously reported patient mutation that inactivates PAPP-A2 in a distal region of the protein. Using a combinational approach, we suggest that PAPP-A2 recognizes IGFBP5 in a similar manner as PAPP-A and show that PAPP-A2 cleaves IGFBP5 less efficiently due to differences in the M2 domain. Overall, our studies characterize the cleavage mechanism of IGFBP5 by PAPP-A2 and shed light onto key differences with its paralog PAPP-A.
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Affiliation(s)
- Janani Sridar
- Calico Life Sciences LLC, South San Francisco, CA, 94080, USA
| | | | | | - Jun Xu
- Calico Life Sciences LLC, South San Francisco, CA, 94080, USA
| | - Kailyn A Kong
- Calico Life Sciences LLC, South San Francisco, CA, 94080, USA
| | - John C K Wang
- Calico Life Sciences LLC, South San Francisco, CA, 94080, USA
| | | | - Georgios Koukos
- Calico Life Sciences LLC, South San Francisco, CA, 94080, USA
| | - Reyna J Simon
- Calico Life Sciences LLC, South San Francisco, CA, 94080, USA
| | - Dan Eaton
- Calico Life Sciences LLC, South San Francisco, CA, 94080, USA
| | | | - Qi Hao
- Calico Life Sciences LLC, South San Francisco, CA, 94080, USA.
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6
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Oxvig C, Conover CA. The Stanniocalcin-PAPP-A-IGFBP-IGF Axis. J Clin Endocrinol Metab 2023; 108:1624-1633. [PMID: 36718521 DOI: 10.1210/clinem/dgad053] [Citation(s) in RCA: 15] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/03/2022] [Revised: 01/20/2023] [Accepted: 01/25/2023] [Indexed: 02/01/2023]
Abstract
The pappalysin metalloproteinases, PAPP-A and PAPP-A2, have emerged as highly specific proteolytic enzymes involved in the regulation of insulin-like growth factor (IGF) signaling. The only known pappalysin substrates are a subset of the IGF binding proteins (IGFBPs), which bind IGF-I or IGF-II with high affinity to antagonize receptor binding. Thus, by cleaving IGFBPs, the pappalysins have the potential to increase IGF bioactivity and hence promote IGF signaling. This is relevant both in systemic and local IGF regulation, in normal and several pathophysiological conditions. Stanniocalcin-1 and -2 were recently found to be potent pappalysin inhibitors, thus comprising the missing components of a complete proteolytic system, the stanniocalcin-PAPP-A-IGFBP-IGF axis. Here, we provide the biological context necessary for understanding the properties of this molecular network, and we review biochemical data, animal experiments, clinical data, and genetic data supporting the physiological operation of this branch as an important part of the IGF system. However, although in vivo data clearly illustrate its power, it is a challenge to understand its subtle operation, for example, multiple equilibria and inhibitory kinetics may determine how, where, and when the IGF receptor is stimulated. In addition, literally all of the regulatory proteins have suspected or known activities that are not directly related to IGF signaling. How such activities may integrate with IGF signaling is also important to address in the future.
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Affiliation(s)
- Claus Oxvig
- Department of Molecular Biology and Genetics, Aarhus University, DK-8000 C, Aarhus, Denmark
| | - Cheryl A Conover
- Division of Endocrinology, Mayo Clinic, Rochester, MN 55905, USA
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7
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Zhong Q, Chu H, Wang G, Zhang C, Li R, Guo F, Meng X, Lei X, Zhou Y, Ren R, Tao L, Li N, Gao N, Wei Y, Qiao J, Hang J. Structural insights into the covalent regulation of PAPP-A activity by proMBP and STC2. Cell Discov 2022; 8:137. [PMID: 36550107 PMCID: PMC9780223 DOI: 10.1038/s41421-022-00502-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2022] [Accepted: 11/25/2022] [Indexed: 12/24/2022] Open
Abstract
Originally discovered in the circulation of pregnant women as a protein secreted by placental trophoblasts, the metalloprotease pregnancy-associated plasma protein A (PAPP-A) is also widely expressed by many other tissues. It cleaves insulin-like growth factor-binding proteins (IGFBPs) to increase the bioavailability of IGFs and plays essential roles in multiple growth-promoting processes. While the vast majority of the circulatory PAPP-A in pregnancy is proteolytically inactive due to covalent inhibition by proform of eosinophil major basic protein (proMBP), the activity of PAPP-A can also be covalently inhibited by another less characterized modulator, stanniocalcin-2 (STC2). However, the structural basis of PAPP-A proteolysis and the mechanistic differences between these two modulators are poorly understood. Here we present two cryo-EM structures of endogenous purified PAPP-A in complex with either proMBP or STC2. Both modulators form 2:2 heterotetramer with PAPP-A and establish extensive interactions with multiple domains of PAPP-A that are distal to the catalytic cleft. This exosite-binding property results in a steric hindrance to prevent the binding and cleavage of IGFBPs, while the IGFBP linker region-derived peptides harboring the cleavage sites are no longer sensitive to the modulator treatment. Functional investigation into proMBP-mediated PAPP-A regulation in selective intrauterine growth restriction (sIUGR) pregnancy elucidates that PAPP-A and proMBP collaboratively regulate extravillous trophoblast invasion and the consequent fetal growth. Collectively, our work reveals a novel covalent exosite-competitive inhibition mechanism of PAPP-A and its regulatory effect on placental function.
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Affiliation(s)
- Qihang Zhong
- grid.411642.40000 0004 0605 3760Center for Reproductive Medicine, Department of Obstetrics and Gynecology, Peking University Third Hospital, Beijing, China ,grid.419897.a0000 0004 0369 313XKey Laboratory of Assisted Reproduction, Ministry of Education, Beijing, China ,Beijing Key Laboratory of Reproductive Endocrinology and Assisted Reproduction, Beijing, China ,grid.411642.40000 0004 0605 3760National Clinical Research Center for Obstetrics and Gynecology, Beijing, China
| | - Honglei Chu
- grid.411642.40000 0004 0605 3760Center for Reproductive Medicine, Department of Obstetrics and Gynecology, Peking University Third Hospital, Beijing, China ,grid.419897.a0000 0004 0369 313XKey Laboratory of Assisted Reproduction, Ministry of Education, Beijing, China ,Beijing Key Laboratory of Reproductive Endocrinology and Assisted Reproduction, Beijing, China ,grid.411642.40000 0004 0605 3760National Clinical Research Center for Obstetrics and Gynecology, Beijing, China
| | - Guopeng Wang
- grid.11135.370000 0001 2256 9319State Key Laboratory of Membrane Biology, School of Life Sciences, Peking University, Beijing, China
| | - Cheng Zhang
- grid.412474.00000 0001 0027 0586Department of Gastrointestinal Oncology, Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education/Beijing), Peking University Cancer Hospital & Institute, Beijing, China
| | - Rong Li
- grid.411642.40000 0004 0605 3760Center for Reproductive Medicine, Department of Obstetrics and Gynecology, Peking University Third Hospital, Beijing, China ,grid.419897.a0000 0004 0369 313XKey Laboratory of Assisted Reproduction, Ministry of Education, Beijing, China ,Beijing Key Laboratory of Reproductive Endocrinology and Assisted Reproduction, Beijing, China ,grid.411642.40000 0004 0605 3760National Clinical Research Center for Obstetrics and Gynecology, Beijing, China
| | - Fusheng Guo
- grid.11135.370000 0001 2256 9319Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Natural and Biomimetic Drugs, Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, Department of Chemical Biology, College of Chemistry and Molecular Engineering, Synthetic and Functional Biomolecules Center, Peking University, Beijing, China ,grid.11135.370000 0001 2256 9319Peking-Tsinghua Center for Life Sciences, Peking University, Beijing, China
| | - Xinlu Meng
- grid.411642.40000 0004 0605 3760Center for Reproductive Medicine, Department of Obstetrics and Gynecology, Peking University Third Hospital, Beijing, China
| | - Xiaoguang Lei
- grid.11135.370000 0001 2256 9319Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Natural and Biomimetic Drugs, Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, Department of Chemical Biology, College of Chemistry and Molecular Engineering, Synthetic and Functional Biomolecules Center, Peking University, Beijing, China ,grid.11135.370000 0001 2256 9319Peking-Tsinghua Center for Life Sciences, Peking University, Beijing, China ,grid.510951.90000 0004 7775 6738Institute for Cancer Research, Shenzhen Bay Laboratory, Shenzhen, Guangdong China
| | - Youli Zhou
- grid.10784.3a0000 0004 1937 0482School of Life and Health Sciences, The Chinese University of Hong Kong, Shenzhen, Guangdong China
| | - Ruobing Ren
- grid.10784.3a0000 0004 1937 0482School of Life and Health Sciences, The Chinese University of Hong Kong, Shenzhen, Guangdong China ,grid.8547.e0000 0001 0125 2443Shanghai Key Laboratory of Metabolic Remodeling and Health, Institute of Metabolism and Integrative Biology, Fudan University, Shanghai, China
| | - Lin Tao
- grid.412636.40000 0004 1757 9485Department of Orthopedics, First Hospital of China Medical University, Shenyang, Liaoning China
| | - Ningning Li
- grid.11135.370000 0001 2256 9319State Key Laboratory of Membrane Biology, School of Life Sciences, Peking University, Beijing, China
| | - Ning Gao
- grid.11135.370000 0001 2256 9319State Key Laboratory of Membrane Biology, School of Life Sciences, Peking University, Beijing, China ,grid.11135.370000 0001 2256 9319Peking-Tsinghua Center for Life Sciences, Peking University, Beijing, China
| | - Yuan Wei
- grid.411642.40000 0004 0605 3760Center for Reproductive Medicine, Department of Obstetrics and Gynecology, Peking University Third Hospital, Beijing, China ,grid.419897.a0000 0004 0369 313XKey Laboratory of Assisted Reproduction, Ministry of Education, Beijing, China ,Beijing Key Laboratory of Reproductive Endocrinology and Assisted Reproduction, Beijing, China ,grid.411642.40000 0004 0605 3760National Clinical Research Center for Obstetrics and Gynecology, Beijing, China
| | - Jie Qiao
- grid.411642.40000 0004 0605 3760Center for Reproductive Medicine, Department of Obstetrics and Gynecology, Peking University Third Hospital, Beijing, China ,grid.419897.a0000 0004 0369 313XKey Laboratory of Assisted Reproduction, Ministry of Education, Beijing, China ,Beijing Key Laboratory of Reproductive Endocrinology and Assisted Reproduction, Beijing, China ,grid.411642.40000 0004 0605 3760National Clinical Research Center for Obstetrics and Gynecology, Beijing, China ,grid.11135.370000 0001 2256 9319Peking-Tsinghua Center for Life Sciences, Peking University, Beijing, China
| | - Jing Hang
- grid.411642.40000 0004 0605 3760Center for Reproductive Medicine, Department of Obstetrics and Gynecology, Peking University Third Hospital, Beijing, China ,grid.419897.a0000 0004 0369 313XKey Laboratory of Assisted Reproduction, Ministry of Education, Beijing, China ,Beijing Key Laboratory of Reproductive Endocrinology and Assisted Reproduction, Beijing, China ,grid.411642.40000 0004 0605 3760National Clinical Research Center for Obstetrics and Gynecology, Beijing, China
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8
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Structure of the proteolytic enzyme PAPP-A with the endogenous inhibitor stanniocalcin-2 reveals its inhibitory mechanism. Nat Commun 2022; 13:6084. [PMID: 36257932 PMCID: PMC9579167 DOI: 10.1038/s41467-022-33698-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Accepted: 09/27/2022] [Indexed: 12/24/2022] Open
Abstract
The metzincin metalloproteinase PAPP-A plays a key role in the regulation of insulin-like growth factor (IGF) signaling by specific cleavage of inhibitory IGF binding proteins (IGFBPs). Using single-particle cryo-electron microscopy (cryo-EM), we here report the structure of PAPP-A in complex with its endogenous inhibitor, stanniocalcin-2 (STC2), neither of which have been reported before. The highest resolution (3.1 Å) was obtained for the STC2 subunit and the N-terminal approximately 1000 residues of the PAPP-A subunit. The 500 kDa 2:2 PAPP-A·STC2 complex is a flexible multidomain ensemble with numerous interdomain contacts. In particular, a specific disulfide bond between the subunits of STC2 and PAPP-A prevents dissociation, and interactions between STC2 and a module located in the very C-terminal end of the PAPP-A subunit prevent binding of its main substrate, IGFBP-4. While devoid of activity towards IGFBP-4, the active site cleft of the catalytic domain is accessible in the inhibited PAPP-A·STC2 complex, as shown by its ability to hydrolyze a synthetic peptide derived from IGFBP-4. Relevant to multiple human pathologies, this unusual mechanism of proteolytic inhibition may support the development of specific pharmaceutical agents, by which IGF signaling can be indirectly modulated.
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9
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Judge RA, Sridar J, Tunyasuvunakool K, Jain R, Wang JCK, Ouch C, Xu J, Mafi A, Nile AH, Remarcik C, Smith CL, Ghosh C, Xu C, Stoll V, Jumper J, Singh AH, Eaton D, Hao Q. Structure of the PAPP-A BP5 complex reveals mechanism of substrate recognition. Nat Commun 2022; 13:5500. [PMID: 36127359 PMCID: PMC9489782 DOI: 10.1038/s41467-022-33175-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Accepted: 09/03/2022] [Indexed: 11/09/2022] Open
Abstract
Insulin-like growth factor (IGF) signaling is highly conserved and tightly regulated by proteases including Pregnancy-Associated Plasma Protein A (PAPP-A). PAPP-A and its paralog PAPP-A2 are metalloproteases that mediate IGF bioavailability through cleavage of IGF binding proteins (IGFBPs). Here, we present single-particle cryo-EM structures of the catalytically inactive mutant PAPP-A (E483A) in complex with a peptide from its substrate IGFBP5 (PAPP-ABP5) and also in its substrate-free form, by leveraging the power of AlphaFold to generate a high quality predicted model as a starting template. We show that PAPP-A is a flexible trans-dimer that binds IGFBP5 via a 25-amino acid anchor peptide which extends into the metalloprotease active site. This unique IGFBP5 anchor peptide that mediates the specific PAPP-A-IGFBP5 interaction is not found in other PAPP-A substrates. Additionally, we illustrate the critical role of the PAPP-A central domain as it mediates both IGFBP5 recognition and trans-dimerization. We further demonstrate that PAPP-A trans-dimer formation and distal inter-domain interactions are both required for efficient proteolysis of IGFBP4, but dispensable for IGFBP5 cleavage. Together the structural and biochemical studies reveal the mechanism of PAPP-A substrate binding and selectivity.
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Affiliation(s)
| | - Janani Sridar
- Calico Life Sciences LLC, South San Francisco, CA, USA
| | | | - Rinku Jain
- AbbVie, 1 North Waukegan Road, North Chicago, IL, USA
| | - John C K Wang
- Calico Life Sciences LLC, South San Francisco, CA, USA
| | - Christna Ouch
- Department of Biochemistry & Molecular Biotechnology, University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - Jun Xu
- Calico Life Sciences LLC, South San Francisco, CA, USA
| | | | - Aaron H Nile
- Calico Life Sciences LLC, South San Francisco, CA, USA
| | | | | | - Crystal Ghosh
- Calico Life Sciences LLC, South San Francisco, CA, USA
| | - Chen Xu
- Department of Biochemistry & Molecular Biotechnology, University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - Vincent Stoll
- AbbVie, 1 North Waukegan Road, North Chicago, IL, USA
| | | | - Amoolya H Singh
- Calico Life Sciences LLC, South San Francisco, CA, USA
- GRAIL, Menlo Park, CA, USA
| | - Dan Eaton
- Calico Life Sciences LLC, South San Francisco, CA, USA.
| | - Qi Hao
- Calico Life Sciences LLC, South San Francisco, CA, USA.
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10
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Pregnancy-Associated Plasma Protein (PAPP)-A2 in Physiology and Disease. Cells 2021; 10:cells10123576. [PMID: 34944082 PMCID: PMC8700087 DOI: 10.3390/cells10123576] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2021] [Revised: 12/09/2021] [Accepted: 12/15/2021] [Indexed: 12/25/2022] Open
Abstract
The growth hormone (GH)/insulin-like growth factor (IGF) axis plays fundamental roles during development, maturation, and aging. Members of this axis, composed of various ligands, receptors, and binding proteins, are regulated in a tissue- and time-specific manner that requires precise control that is not completely understood. Some of the most recent advances in understanding the implications of this axis in human growth are derived from the identifications of new mutations in the gene encoding the pregnancy-associated plasma protein PAPP-A2 protease that liberates IGFs from their carrier proteins in a selective manner to allow binding to the IGF receptor 1. The identification of three nonrelated families with mutations in the PAPP-A2 gene has shed light on how this protease affects human physiology. This review summarizes our understanding of the implications of PAPP-A2 in growth physiology, obtained from studies in genetically modified animal models and the PAPP-A2 deficient patients known to date.
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11
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Mohrin M, Liu J, Zavala‐Solorio J, Bhargava S, Maxwell Trumble J, Brito A, Hu D, Brooks D, Koukos G, Alabdulaaly L, Paw JS, Hake K, Kolumam G, Bouxsein ML, Baron R, Kutskova Y, Freund A. Inhibition of longevity regulator PAPP-A modulates tissue homeostasis via restraint of mesenchymal stromal cells. Aging Cell 2021; 20:e13313. [PMID: 33561324 PMCID: PMC7963332 DOI: 10.1111/acel.13313] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Revised: 11/08/2020] [Accepted: 12/31/2020] [Indexed: 12/20/2022] Open
Abstract
Pregnancy-associated plasma protein-A (PAPP-A) is a secreted metalloprotease that increases insulin-like growth factor (IGF) availability by cleaving IGF-binding proteins. Reduced IGF signaling extends longevity in multiple species, and consistent with this, PAPP-A deletion extends lifespan and healthspan; however, the mechanism remains unclear. To clarify PAPP-A's role, we developed a PAPP-A neutralizing antibody and treated adult mice with it. Transcriptomic profiling across tissues showed that anti-PAPP-A reduced IGF signaling and extracellular matrix (ECM) gene expression system wide. The greatest reduction in IGF signaling occurred in the bone marrow, where we found reduced bone, marrow adiposity, and myelopoiesis. These diverse effects led us to search for unifying mechanisms. We identified mesenchymal stromal cells (MSCs) as the source of PAPP-A in bone marrow and primary responders to PAPP-A inhibition. Mice treated with anti-PAPP-A had reduced IGF signaling in MSCs and dramatically decreased MSC number. As MSCs are (1) a major source of ECM and the progenitors of ECM-producing fibroblasts, (2) the originating source of adult bone, (3) regulators of marrow adiposity, and (4) an essential component of the hematopoietic niche, our data suggest that PAPP-A modulates bone marrow homeostasis by potentiating the number and activity of MSCs. We found that MSC-like cells are the major source of PAPP-A in other tissues also, suggesting that reduced MSC-like cell activity drives the system-wide reduction in ECM gene expression due to PAPP-A inhibition. Dysregulated ECM production is associated with aging and drives age-related diseases, and thus, this may be a mechanism by which PAPP-A deficiency enhances longevity.
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Affiliation(s)
- Mary Mohrin
- Calico Life Sciences LLCSouth San FranciscoCAUSA
| | - Justin Liu
- Calico Life Sciences LLCSouth San FranciscoCAUSA
| | | | | | | | | | - Dorothy Hu
- Harvard School of Dental MedicineBostonMAUSA
| | - Daniel Brooks
- Center for Advanced Orthopaedic StudiesBeth Israel Deaconess Medical CenterBostonMAUSA
| | | | | | | | - Kayley Hake
- Calico Life Sciences LLCSouth San FranciscoCAUSA
| | | | - Mary L. Bouxsein
- Center for Advanced Orthopaedic StudiesBeth Israel Deaconess Medical CenterBostonMAUSA
- Harvard Medical SchoolBostonMAUSA
| | - Roland Baron
- Harvard School of Dental MedicineBostonMAUSA
- Harvard Medical SchoolBostonMAUSA
| | | | - Adam Freund
- Calico Life Sciences LLCSouth San FranciscoCAUSA
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12
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Liu C, Li S, Noer PR, Kjaer-Sorensen K, Juhl AK, Goldstein A, Ke C, Oxvig C, Duan C. The metalloproteinase Papp-aa controls epithelial cell quiescence-proliferation transition. eLife 2020; 9:e52322. [PMID: 32293560 PMCID: PMC7185994 DOI: 10.7554/elife.52322] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Accepted: 04/11/2020] [Indexed: 02/06/2023] Open
Abstract
Human patients carrying PAPP-A2 inactivating mutations have low bone mineral density. The underlying mechanisms for this reduced calcification are poorly understood. Using a zebrafish model, we report that Papp-aa regulates bone calcification by promoting Ca2+-transporting epithelial cell (ionocyte) quiescence-proliferation transition. Ionocytes, which are normally quiescent, re-enter the cell cycle under low [Ca2+] stress. Genetic deletion of Papp-aa, but not the closely related Papp-ab, abolished ionocyte proliferation and reduced calcified bone mass. Loss of Papp-aa expression or activity resulted in diminished IGF1 receptor-Akt-Tor signaling in ionocytes. Under low Ca2+ stress, Papp-aa cleaved Igfbp5a. Under normal conditions, however, Papp-aa proteinase activity was suppressed and IGFs were sequestered in the IGF/Igfbp complex. Pharmacological disruption of the IGF/Igfbp complex or adding free IGF1 activated IGF signaling and promoted ionocyte proliferation. These findings suggest that Papp-aa-mediated local Igfbp5a cleavage functions as a [Ca2+]-regulated molecular switch linking IGF signaling to bone calcification by stimulating epithelial cell quiescence-proliferation transition under low Ca2+ stress.
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Affiliation(s)
- Chengdong Liu
- Department of Molecular, Cellular, and Developmental Biology, University of MichiganAnn ArborUnited States
| | - Shuang Li
- Department of Molecular, Cellular, and Developmental Biology, University of MichiganAnn ArborUnited States
- College of Ocean and Earth Sciences, Xiamen UniversityXiamenChina
| | | | | | - Anna Karina Juhl
- Department of Molecular Biology and Genetics, Aarhus UniversityAarhusDenmark
| | - Allison Goldstein
- Department of Molecular, Cellular, and Developmental Biology, University of MichiganAnn ArborUnited States
| | - Caihuan Ke
- College of Ocean and Earth Sciences, Xiamen UniversityXiamenChina
| | - Claus Oxvig
- Department of Molecular Biology and Genetics, Aarhus UniversityAarhusDenmark
| | - Cunming Duan
- Department of Molecular, Cellular, and Developmental Biology, University of MichiganAnn ArborUnited States
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13
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Lloyd KA, Parsons BN, Burkitt MD, Moore AR, Papoutsopoulou S, Boyce M, Duckworth CA, Exarchou K, Howes N, Rainbow L, Fang Y, Oxvig C, Dodd S, Varro A, Hall N, Pritchard DM. Netazepide Inhibits Expression of Pappalysin 2 in Type 1 Gastric Neuroendocrine Tumors. Cell Mol Gastroenterol Hepatol 2020; 10:113-132. [PMID: 32004755 PMCID: PMC7215182 DOI: 10.1016/j.jcmgh.2020.01.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/03/2020] [Revised: 01/23/2020] [Accepted: 01/23/2020] [Indexed: 12/14/2022]
Abstract
BACKGROUND & AIMS In patients with autoimmune atrophic gastritis and achlorhydria, hypergastrinemia is associated with the development of type 1 gastric neuroendocrine tumors (gNETs). Twelve months of treatment with netazepide (YF476), an antagonist of the cholecystokinin B receptor (CCKBR or CCK2R), eradicated some type 1 gNETs in patients. We investigated the mechanisms by which netazepide induced gNET regression using gene expression profiling. METHODS We obtained serum samples and gastric corpus biopsy specimens from 8 patients with hypergastrinemia and type 1 gNETs enrolled in a phase 2 trial of netazepide. Control samples were obtained from 10 patients without gastric cancer. We used amplified and biotinylated sense-strand DNA targets from total RNA and Affymetrix (Thermofisher Scientific, UK) Human Gene 2.0 ST microarrays to identify differentially expressed genes in stomach tissues from patients with type 1 gNETs before, during, and after netazepide treatment. Findings were validated in a human AGSGR gastric adenocarcinoma cell line that stably expresses human CCK2R, primary mouse gastroids, transgenic hypergastrinemic INS-GAS mice, and patient samples. RESULTS Levels of pappalysin 2 (PAPPA2) messenger RNA were reduced significantly in gNET tissues from patients receiving netazepide therapy compared with tissues collected before therapy. PAPPA2 is a metalloproteinase that increases the bioavailability of insulin-like growth factor (IGF) by cleaving IGF binding proteins (IGFBPs). PAPPA2 expression was increased in the gastric corpus of patients with type 1 gNETs, and immunohistochemistry showed localization in the same vicinity as CCK2R-expressing enterochromaffin-like cells. Up-regulation of PAPPA2 also was found in the stomachs of INS-GAS mice. Gastrin increased PAPPA2 expression with time and in a dose-dependent manner in gastric AGSGR cells and mouse gastroids by activating CCK2R. Knockdown of PAPPA2 in AGSGR cells with small interfering RNAs significantly decreased their migratory response and tissue remodeling in response to gastrin. Gastrin altered the expression and cleavage of IGFBP3 and IGFBP5. CONCLUSIONS In an analysis of human gNETS and mice, we found that gastrin up-regulates the expression of gastric PAPPA2. Increased PAPPA2 alters IGF bioavailability, cell migration, and tissue remodeling, which are involved in type 1 gNET development. These effects are inhibited by netazepide.
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Affiliation(s)
- Katie A Lloyd
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom
| | - Bryony N Parsons
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom
| | - Michael D Burkitt
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom
| | - Andrew R Moore
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom; Liverpool University Hospitals, National Health Service Foundation Trust, Liverpool, United Kingdom
| | - Stamatia Papoutsopoulou
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom
| | - Malcolm Boyce
- Trio Medicines, Ltd, Hammersmith Medicines Research, London, United Kingdom
| | - Carrie A Duckworth
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom
| | - Klaire Exarchou
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom; Liverpool University Hospitals, National Health Service Foundation Trust, Liverpool, United Kingdom
| | - Nathan Howes
- Liverpool University Hospitals, National Health Service Foundation Trust, Liverpool, United Kingdom
| | - Lucille Rainbow
- Centre for Genomic Research, Institute of Integrative Biology, University of Liverpool, Liverpool, United Kingdom
| | - Yongxiang Fang
- Centre for Genomic Research, Institute of Integrative Biology, University of Liverpool, Liverpool, United Kingdom
| | - Claus Oxvig
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus C, Denmark
| | - Steven Dodd
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom
| | - Andrea Varro
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom
| | - Neil Hall
- Centre for Genomic Research, Institute of Integrative Biology, University of Liverpool, Liverpool, United Kingdom; The Earlham Institute, Norwich, Norfolk, United Kingdom; School of Biological Sciences, University of East Anglia, Norwich, Norfolk, United Kingdom
| | - D Mark Pritchard
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom; Liverpool University Hospitals, National Health Service Foundation Trust, Liverpool, United Kingdom.
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14
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Slocum E, Germain D. Collagen and PAPP-A in the Etiology of Postpartum Breast Cancer. Discov Oncol 2019; 10:137-144. [PMID: 31631239 DOI: 10.1007/s12672-019-00368-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Accepted: 09/29/2019] [Indexed: 01/14/2023] Open
Abstract
Pregnancy has a dual effect on the risk of breast cancer. On one hand, pregnancy at a young age is known to be protective. However, pregnancy is also associated with a transient increased risk of breast cancer. For women that have children after the age of 30, the risk remains higher than women who never had children for decades. Involution of the breast has been identified as a window of mammary development associated with the adverse effect of pregnancy. In this review, we summarize the current understanding of the role of involution and describe the role of collagen in this setting. We also discuss the role of a collagen-dependent protease, pappalysin-1, in postpartum breast cancer and its role in activating both insulin-like growth factor signaling and discoidin domain collagen receptor 2, DDR2. Together, these novel advances in our understanding of postpartum breast cancer open the way to targeted therapies against this aggressive breast cancer sub-type.
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Affiliation(s)
- Elizabeth Slocum
- Department of Medicine, Division of Hematology/Oncology, Icahn School of Medicine at Mount Sinai, Tisch Cancer Institute, New York, NY, 10029, USA
| | - Doris Germain
- Department of Medicine, Division of Hematology/Oncology, Icahn School of Medicine at Mount Sinai, Tisch Cancer Institute, New York, NY, 10029, USA.
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15
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Steffensen LB, Conover CA, Oxvig C. PAPP-A and the IGF system in atherosclerosis: what's up, what's down? Am J Physiol Heart Circ Physiol 2019; 317:H1039-H1049. [PMID: 31518159 DOI: 10.1152/ajpheart.00395.2019] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Pregnancy-associated plasma protein-A (PAPP-A) is a metalloproteinase with a well-established role in releasing bioactive insulin-like growth factor-1 (IGF-1) from IGF-binding protein-2, -4, and -5 by proteolytic processing of these. The IGF system has repeatedly been suggested to be involved in the pathology of atherosclerosis, and both PAPP-A and IGF-1 are proposed biomarkers and therapeutic targets for this disease. Several experimental approaches based on atherosclerosis mouse models have been undertaken to obtain causative and mechanistic insight to the role of these molecules in atherogenesis. However, reports seem conflicting. The literature suggests that PAPP-A is detrimental, while IGF-1 is beneficial. This raises important questions that need to be addressed. Here we summarize the various studies and discuss potential underlying explanations for this seemingly inconsistency with the objective of better understanding complexities and limitations when manipulating the IGF system in mouse models of atherosclerosis. A debate clarifying what's up and what's down is highly warranted going forward with the ultimate goal of improving atherosclerosis therapy by targeting the IGF system.
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Affiliation(s)
- Lasse B Steffensen
- Centre for Individualized Medicine in Arterial Diseases, Odense University Hospital, Odense, Denmark
| | | | - Claus Oxvig
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark
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16
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Bøtkjær JA, Noer PR, Oxvig C, Yding Andersen C. A common variant of the pregnancy-associated plasma protein-A (PAPPA) gene encodes a protein with reduced proteolytic activity towards IGF-binding proteins. Sci Rep 2019; 9:13231. [PMID: 31519945 PMCID: PMC6744435 DOI: 10.1038/s41598-019-49626-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Accepted: 07/05/2019] [Indexed: 02/03/2023] Open
Abstract
Pregnancy-associated plasma protein-A (PAPP-A) is a key regulator of insulin-like growth factor (IGF) bioactivity, by releasing the IGFs from their corresponding IGF-binding proteins (IGFBPs). The minor allele of the single nucleotide polymorphism (SNP), rs7020782 (serine < tyrosine), in PAPPA has previously been associated with recurrent pregnancy loss as well as with significant reduced levels of PAPP-A protein in human ovarian follicles. The aim of the present study was to reveal a possible functional effect of the rs7020782 SNP in PAPPA by comparing recombinant PAPP-A proteins from transfected human embryonic kidney 293 T cells. The proteolytic cleavage of IGFBP-4 was shown to be affected by the rs7020782 SNP in PAPPA, showing a significantly reduced cleavage rate for the serine variant compared to the tyrosine variant (p-value < 0.001). The serine variant also showed a trend towards reduced cleavage rates, that was not significant, towards IGFBP-2 and IGFBP-5 compared to the tyrosine variant. No differences were found when analysing cell surface binding, complex formation between PAPP-A and STC2 or proMBP, nor when analysing STC1 inhibition of PAPP-A-mediated IGFBP-4 cleavage. Regulation of IGF bioactivity in reproductive tissues is important and the rs7020782 SNP in PAPPA may disturb this regulation by altering the specific activity of PAPP-A.
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Affiliation(s)
- Jane Alrø Bøtkjær
- Laboratory of Reproductive Biology, The Juliane Marie Centre for Women, Children and Reproduction, Rigshospitalet, Copenhagen University Hospital, Copenhagen University, Copenhagen, DK-2100, Denmark.
| | - Pernille Rimmer Noer
- Department of Molecular Biology and Genetics, University of Aarhus, Aarhus, DK-8000, Denmark
| | - Claus Oxvig
- Department of Molecular Biology and Genetics, University of Aarhus, Aarhus, DK-8000, Denmark
| | - Claus Yding Andersen
- Laboratory of Reproductive Biology, The Juliane Marie Centre for Women, Children and Reproduction, Rigshospitalet, Copenhagen University Hospital, Copenhagen University, Copenhagen, DK-2100, Denmark
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17
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Yu XH, He LH, Gao JH, Zhang DW, Zheng XL, Tang CK. Pregnancy-associated plasma protein-A in atherosclerosis: Molecular marker, mechanistic insight, and therapeutic target. Atherosclerosis 2018; 278:250-258. [DOI: 10.1016/j.atherosclerosis.2018.10.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Revised: 09/10/2018] [Accepted: 10/04/2018] [Indexed: 12/20/2022]
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18
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Hjortebjerg R. IGFBP-4 and PAPP-A in normal physiology and disease. Growth Horm IGF Res 2018; 41:7-22. [PMID: 29864720 DOI: 10.1016/j.ghir.2018.05.002] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/27/2018] [Revised: 05/15/2018] [Accepted: 05/29/2018] [Indexed: 02/07/2023]
Abstract
Insulin-like growth factor (IGF) binding protein-4 (IGFBP-4) is a modulator of the IGF system, exerting both inhibitory and stimulatory effects on IGF-induced cellular growth. IGFBP-4 is the principal substrate for the enzyme pregnancy-associated plasma protein-A (PAPP-A). Through IGF-dependent cleavage of IGFBP-4 in the vicinity of the IGF receptor, PAPP-A is able to increase IGF bioavailability and stimulate IGF-mediated growth. Recently, the stanniocalcins (STCs) were identified as novel inhibitors of PAPP-A proteolytic activity, hereby adding additional members to the seemingly endless list of proteins belonging to the IGF family. Our understanding of these proteins has advanced throughout recent years, and there is evidence to suggest that the role of IGFBP-4 and PAPP-A in defining the relationship between total IGF and IGF bioactivity can be linked to a number of pathological conditions. This review provides an overview of the experimental and clinical findings on the IGFBP-4/PAPP-A/STC axis as a regulator of IGF activity and examines the conundrum surrounding extrapolation of circulating concentrations to tissue action of these proteins. The primary focus will be on the biological significance of IGFBP-4 and PAPP-A in normal physiology and in pathophysiology with emphasis on metabolic disorders, cardiovascular diseases, and cancer. Finally, the review assesses current new trajectories of IGFBP-4 and PAPP-A research.
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Affiliation(s)
- Rikke Hjortebjerg
- Medical Research Laboratory, Department of Clinical Medicine, Faculty of Health, Aarhus University, Aarhus, Denmark; The Danish Diabetes Academy, Odense, Denmark.
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19
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Abstract
The zinc metalloproteinase, PAPP-A, enhances local insulin-like growth factor (IGF) action through cleavage of inhibitory IGF-binding proteins, thereby increasing IGF available for IGF receptor-mediated cell proliferation, migration and survival. In many tumors, enhanced IGF receptor signaling is associated with tumor growth, invasion and metastasis. We will first discuss PAPP-A structure and function, and post-translational inhibitors of PAPP-A expression or proteolytic activity. We will then review the evidence supporting an important role for PAPP-A in many cancers, including breast, ovarian and lung cancer, and Ewing sarcoma.
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Affiliation(s)
- Cheryl A Conover
- From the Division of Endocrinology Mayo ClinicRochester, Minnesota, USA
| | - Claus Oxvig
- Department of Molecular Biology and GeneticsAarhus University, Aarhus, Denmark
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20
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Beattie J, Al-Khafaji H, Noer PR, Alkharobi HE, Alhodhodi A, Meade J, El-Gendy R, Oxvig C. Insulin- like Growth Factor-Binding Protein Action in Bone Tissue: A Key Role for Pregnancy- Associated Plasma Protein-A. Front Endocrinol (Lausanne) 2018; 9:31. [PMID: 29503631 PMCID: PMC5820303 DOI: 10.3389/fendo.2018.00031] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/24/2017] [Accepted: 01/23/2018] [Indexed: 11/13/2022] Open
Abstract
The insulin-like growth factor (IGF) axis is required for the differentiation, development, and maintenance of bone tissue. Accordingly, dysregulation of this axis is associated with various skeletal pathologies including growth abnormalities and compromised bone structure. It is becoming increasingly apparent that the action of the IGF axis must be viewed holistically taking into account not just the actions of the growth factors and receptors, but also the influence of soluble high affinity IGF binding proteins (IGFBPs).There is a recognition that IGFBPs exert IGF-dependent and IGF-independent effects in bone and other tissues and that an understanding of the mechanisms of action of IGFBPs and their regulation in the pericellular environment impact critically on tissue physiology. In this respect, a group of IGFBP proteinases (which may be considered as ancillary members of the IGF axis) play a crucial role in regulating IGFBP function. In this model, cleavage of IGFBPs by specific proteinases into fragments with lower affinity for growth factor(s) regulates the partition of IGFs between IGFBPs and cell surface IGF receptors. In this review, we examine the importance of IGFBP function in bone tissue with special emphasis on the role of pregnancy associated plasma protein-A (PAPP-A). We examine the function of PAPP-A primarily as an IGFBP-4 proteinase and present evidence that PAPP-A induced cleavage of IGFBP-4 is potentially a key regulatory step in bone metabolism. We also highlight some recent findings with regard to IGFBP-2 and IGFBP-5 (also PAPP-A substrates) function in bone tissue and briefly discuss the actions of the other three IGFBPs (-1, -3, and -6) in this tissue. Although our main focus will be in bone we will allude to IGFBP activity in other cells and tissues where appropriate.
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Affiliation(s)
- James Beattie
- Division of Oral Biology, Leeds School of Dentistry, Level 7 Wellcome Trust Brenner Building, University of Leeds, St James University Hospital, Leeds, United Kingdom
- *Correspondence: James Beattie,
| | - Hasanain Al-Khafaji
- Division of Oral Biology, Leeds School of Dentistry, Level 7 Wellcome Trust Brenner Building, University of Leeds, St James University Hospital, Leeds, United Kingdom
| | - Pernille R. Noer
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark
| | - Hanaa Esa Alkharobi
- Department of Oral Biology, Dental College, King AbdulAziz University, Jeddah, Saudi Arabia
| | - Aishah Alhodhodi
- Division of Oral Biology, Leeds School of Dentistry, Level 7 Wellcome Trust Brenner Building, University of Leeds, St James University Hospital, Leeds, United Kingdom
| | - Josephine Meade
- Division of Oral Biology, Leeds School of Dentistry, Level 7 Wellcome Trust Brenner Building, University of Leeds, St James University Hospital, Leeds, United Kingdom
| | - Reem El-Gendy
- Division of Oral Biology, Leeds School of Dentistry, Level 7 Wellcome Trust Brenner Building, University of Leeds, St James University Hospital, Leeds, United Kingdom
- Department of Oral Pathology, Faculty of Dentistry, Suez Canal University, Ismailia, Egypt
| | - Claus Oxvig
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark
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21
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Conover CA, Oxvig C. PAPP-A: a promising therapeutic target for healthy longevity. Aging Cell 2017; 16:205-209. [PMID: 28035757 PMCID: PMC5334524 DOI: 10.1111/acel.12564] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/25/2016] [Indexed: 12/16/2022] Open
Abstract
Pregnancy-associated plasma protein-A (PAPP-A) is a proteolytic enzyme that was discovered to increase local insulin-like growth factor (IGF) availability for receptor activation through cleavage of inhibitory IGF binding proteins (IGFBPs). Reduced IGF signaling has been associated with increased lifespan and healthspan. Therefore, inhibition of PAPP-A represents a novel approach to indirectly decrease the availability of bioactive IGF. Here, we will review data in support of PAPP-A as a therapeutic target to promote healthy longevity.
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Affiliation(s)
| | - Claus Oxvig
- Department of Molecular Biology and Genetics; Aarhus Universitet; Aarhus Denmark
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22
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PAPP-A and the IGF system. ANNALES D'ENDOCRINOLOGIE 2016; 77:90-6. [DOI: 10.1016/j.ando.2016.04.015] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2016] [Accepted: 04/11/2016] [Indexed: 01/25/2023]
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23
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van Meel E, Lee WS, Liu L, Qian Y, Doray B, Kornfeld S. Multiple Domains of GlcNAc-1-phosphotransferase Mediate Recognition of Lysosomal Enzymes. J Biol Chem 2016; 291:8295-307. [PMID: 26833567 PMCID: PMC4825028 DOI: 10.1074/jbc.m116.714568] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2016] [Revised: 01/28/2016] [Indexed: 12/24/2022] Open
Abstract
The Golgi enzyme UDP-GlcNAc:lysosomal enzymeN-acetylglucosamine-1-phosphotransferase (GlcNAc-1-phosphotransferase), an α2β2γ2hexamer, mediates the initial step in the addition of the mannose 6-phosphate targeting signal on newly synthesized lysosomal enzymes. This tag serves to direct the lysosomal enzymes to lysosomes. A key property of GlcNAc-1-phosphotransferase is its unique ability to distinguish the 60 or so lysosomal enzymes from the numerous non-lysosomal glycoproteins with identical Asn-linked glycans. In this study, we demonstrate that the two Notch repeat modules and the DNA methyltransferase-associated protein interaction domain of the α subunit are key components of this recognition process. Importantly, different combinations of these domains are involved in binding to individual lysosomal enzymes. This study also identifies the γ-binding site on the α subunit and demonstrates that in the majority of instances the mannose 6-phosphate receptor homology domain of the γ subunit is required for optimal phosphorylation. These findings serve to explain how GlcNAc-1-phosphotransferase recognizes a large number of proteins that lack a common structural motif.
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Affiliation(s)
- Eline van Meel
- From the Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Wang-Sik Lee
- From the Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Lin Liu
- From the Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Yi Qian
- From the Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Balraj Doray
- From the Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Stuart Kornfeld
- From the Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri 63110
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Brohus M, Gorbunova V, Faulkes CG, Overgaard MT, Conover CA. The Insulin-Like Growth Factor System in the Long-Lived Naked Mole-Rat. PLoS One 2015; 10:e0145587. [PMID: 26694858 PMCID: PMC4694111 DOI: 10.1371/journal.pone.0145587] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2015] [Accepted: 12/04/2015] [Indexed: 11/29/2022] Open
Abstract
Naked mole-rats (Heterocephalus glaber) (NMRs) are the longest living rodents known. They show negligible senescence, and are resistant to cancers and certain damaging effects associated with aging. The insulin-like growth factors (IGFs) have pluripotent actions, influencing growth processes in virtually every system of the body. They are established contributors to the aging process, confirmed by the demonstration that decreased IGF signaling results in life-extending effects in a variety of species. The IGFs are likewise involved in progression of cancers by mediating survival signals in malignant cells. This report presents a full characterization of the IGF system in the NMR: ligands, receptors, IGF binding proteins (IGFBPs), and IGFBP proteases. A particular emphasis was placed on the IGFBP protease, pregnancy-associated plasma protein-A (PAPP-A), shown to be an important lifespan modulator in mice. Comparisons of IGF-related genes in the NMR with human and murine sequences indicated no major differences in essential parts of the IGF system, including PAPP-A. The protease was shown to possess an intact active site despite the report of a contradictory genome sequence. Furthermore, PAPP-A was expressed and translated in NMRs cells and retained IGF-dependent proteolytic activity towards IGFBP-4 and IGF-independent activity towards IGFBP-5. However, experimental data suggest differential regulatory mechanisms for PAPP-A expression in NMRs than those described in humans and mice. This overall description of the IGF system in the NMR represents an initial step towards elucidating the complex molecular mechanisms underlying longevity, and how these animals have evolved to ensure a delayed and healthy aging process.
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Affiliation(s)
- Malene Brohus
- The Division of Endocrinology, Mayo Clinic, 200 First Street SW, Rochester, Minnesota 55905, United States of America
- Department of Chemistry and Bioscience, Aalborg University, Frederik Bajers Vej 7H, DK-9220 Aalborg Oe, Denmark
| | - Vera Gorbunova
- University of Rochester, Department of Biology, 434 Hutchinson Hall, River Campus, Rochester, New York, 14627, United States of America
| | - Chris G. Faulkes
- School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London E1 4NS, United Kingdom
| | - Michael T. Overgaard
- Department of Chemistry and Bioscience, Aalborg University, Frederik Bajers Vej 7H, DK-9220 Aalborg Oe, Denmark
| | - Cheryl A. Conover
- The Division of Endocrinology, Mayo Clinic, 200 First Street SW, Rochester, Minnesota 55905, United States of America
- * E-mail:
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Mikkelsen JH, Resch ZT, Kalra B, Savjani G, Kumar A, Conover CA, Oxvig C. Indirect targeting of IGF receptor signaling in vivo by substrate-selective inhibition of PAPP-A proteolytic activity. Oncotarget 2015; 5:1014-25. [PMID: 24572990 PMCID: PMC4011579 DOI: 10.18632/oncotarget.1629] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The insulin-like growth factor (IGF) signaling pathway is involved in certain human cancers, and the feasibility of directly targeting the IGF receptor has been actively investigated. However, recent evidence from clinical trials suggests that this approach can be problematic. We have developed an alternative strategy to indirectly inhibit the IGF signaling by targeting the metalloproteinase, pregnancy-associated plasma protein-A (PAPP-A). PAPP-A associated with the cell surface cleaves IGF binding protein-4 (IGFBP-4), when IGF is bound to IGFBP-4, and thereby increases IGF bioavailability for receptor activation in an autocrine/paracrine manner. We hypothesized that inhibition of PAPP-A would suppress excessive local IGF signaling in tissues where this is caused by increased PAPP-A proteolytic activity. To test this hypothesis, we developed an inhibitory monoclonal antibody, mAb 1/41, which targets a unique substrate-binding exosite of PAPP-A. This inhibitor selectively and specifically inhibits proteolytic cleavage of IGFBP-4 with an inhibitory constant (Ki) of 135 pM. In addition, it inhibited intracellular signaling of the IGF receptor (AKT phosphorylation) in monolayers of A549 cells, an IGF-responsive lung cancer-derived cell line found to express high levels of PAPP-A. We further showed that mAb 1/41 is effective towards PAPP-A bound to cell surfaces, and that it is capable of inhibiting PAPP-A activity in vivo. Using a murine xenograft model of A549 cells, we demonstrated that mAb 1/41 administered intraperitoneally significantly inhibited tumor growth. Analysis of xenograft tumor tissue recovered from treated mice showed penetration of mAb 1/41, reduced IGFBP-4 proteolysis, and reduced AKT phosphorylation. Our study provides proof of concept that IGF signaling can be selectively reduced by targeting a regulatory proteinase that functions extracellularly, upstream of the IGF receptor. PAPP-A targeting thus represents an alternative therapeutic strategy for inhibiting IGF receptor signaling.
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Affiliation(s)
- Jakob H Mikkelsen
- Department of Molecular Biology and Genetics, University of Aarhus, DK-8000 Aarhus C, Denmark
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The role of PAPP-A in the IGF system: location, location, location. J Cell Commun Signal 2015; 9:177-87. [PMID: 25617049 DOI: 10.1007/s12079-015-0259-9] [Citation(s) in RCA: 133] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2014] [Accepted: 01/12/2015] [Indexed: 12/15/2022] Open
Abstract
Although discovered as a placental protein present abundantly in the circulation of pregnant women, pregnancy-associated plasma protein-A (PAPP-A) is widely expressed in multiple tissues. PAPP-A is a highly specific metalloproteinase binding tightly to glycosaminoglycans present on the surface of cells. By cleaving a subset of insulin-like growth factor binding proteins (IGFBPs), PAPP-A thus functions within tissues as a growth-promoting enzyme, releasing bioactive IGF in close proximity to the IGF receptor. IGFBP-4 is believed to be the principal PAPP-A substrate, and the focus in this review is on PAPP-A enzymatic activity and its role in the PAPP-A-IGFBP-4-IGF axis, which is subject to regulation at several different levels. These include e.g., transcriptional control, competing reactions potentially sequestering IGF from IGFBP-4 and hence antagonizing PAPP-A-mediated IGF activation, and proteolytic inhibition of PAPP-A. The latter may involve the protein stanniocalcin-2 (STC2), recently found to potently inhibit PAPP-A activity by forming a covalent complex with PAPP-A. PAPP-A or complex-bound variants may escape from pathological tissues into the circulation. It is emphasized that the potential use of PAPP-A as a diagnostic or predictive biomarker in nonpregnant individuals requires precise knowledge of analyte identity and assay specificity in addition to an appropriate material for standardization. Finally, PAPP-A may serve as a therapeutic target to indirectly inhibit IGF signaling in tissues where this is driven by increased PAPP-A activity. By taking advantage of the intricate interaction between PAPP-A and IGFBP-4, highly specific and selective inhibition of PAPP-A is possible.
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Jepsen MR, Kløverpris S, Mikkelsen JH, Pedersen JH, Füchtbauer EM, Laursen LS, Oxvig C. Stanniocalcin-2 inhibits mammalian growth by proteolytic inhibition of the insulin-like growth factor axis. J Biol Chem 2014; 290:3430-9. [PMID: 25533459 DOI: 10.1074/jbc.m114.611665] [Citation(s) in RCA: 106] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Mammalian stanniocalcin-2 (STC2) is a secreted polypeptide widely expressed in developing and adult tissues. However, although transgenic expression in mice is known to cause severe dwarfism, and targeted deletion of STC2 causes increased postnatal growth, its precise biological role is still unknown. We found that STC2 potently inhibits the proteolytic activity of the growth-promoting metalloproteinase, pregnancy-associated plasma protein-A (PAPP-A). Proteolytic inhibition requires covalent binding of STC2 to PAPP-A and is mediated by a disulfide bond, which involves Cys-120 of STC2. Binding of STC2 prevents PAPP-A cleavage of insulin-like growth factor-binding protein (IGFBP)-4 and hence release within tissues of bioactive IGF, required for normal growth. Concordantly, we show that STC2 efficiently inhibits PAPP-A-mediated IGF receptor signaling in vitro and that transgenic mice expressing a mutated variant of STC2, STC2(C120A), which is unable to inhibit PAPP-A, grow like wild-type mice. Our work identifies STC2 as a novel proteinase inhibitor and a previously unrecognized extracellular component of the IGF system.
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Affiliation(s)
- Malene R Jepsen
- From the Department of Molecular Biology and Genetics, Aarhus University, DK-8000 Aarhus, Denmark
| | - Søren Kløverpris
- From the Department of Molecular Biology and Genetics, Aarhus University, DK-8000 Aarhus, Denmark
| | - Jakob H Mikkelsen
- From the Department of Molecular Biology and Genetics, Aarhus University, DK-8000 Aarhus, Denmark
| | - Josefine H Pedersen
- From the Department of Molecular Biology and Genetics, Aarhus University, DK-8000 Aarhus, Denmark
| | - Ernst-Martin Füchtbauer
- From the Department of Molecular Biology and Genetics, Aarhus University, DK-8000 Aarhus, Denmark
| | - Lisbeth S Laursen
- From the Department of Molecular Biology and Genetics, Aarhus University, DK-8000 Aarhus, Denmark
| | - Claus Oxvig
- From the Department of Molecular Biology and Genetics, Aarhus University, DK-8000 Aarhus, Denmark
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Abstract
Pregnancy-associated plasma protein A (PAPP-A) is a key regulator of insulin-like growth factor bioavailability essential for normal fetal development. In maternal blood, this protein increases with gestational age and then rapidly decreases after delivery. It is routinely used for Down syndrome screening in the first trimester of pregnancy, and its decrease compared to a normal pregnancy indicates an increased risk for both chromosomal anomalies and adverse pregnancy outcomes. It belongs to a group of biomarkers that predict later preeclampsia development, primarily early onset preeclampsia; however, it should be combined with a Doppler ultrasonography of the uterine artery (pulsatile index) and other biochemical and maternal factors to achieve a higher detection rate with an acceptable false positivity rate. Some studies have demonstrated an even more pronounced decrease of PAPP-A in the early second trimester of pregnancy in women who subsequently develop preeclampsia compared with women who do not develop preeclampsia. Conversely, during the last trimester of pregnancy, its concentration increases even more in patients with preeclampsia than in patients without. It is also detectable at very low levels in nonpregnant individuals, and a higher concentration indicates an adverse effect in patients with acute coronary syndromes or stable atherosclerotic disease and in patients with end-stage renal disease who are being treated with hemodialysis.
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Kjaer-Sorensen K, Engholm DH, Jepsen MR, Morch MG, Weyer K, Hefting LL, Skov LL, Laursen LS, Oxvig C. Pregnancy-associated plasma protein-A2 modulates development of cranial cartilage and angiogenesis in zebrafish embryos. J Cell Sci 2014; 127:5027-37. [DOI: 10.1242/jcs.152587] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
Abstract
Pregnancy-associated plasma protein-A2 (PAPP-A2, pappalysin-2) is a large metalloproteinase, known to be required for normal postnatal growth and bone development in mice. We here report the detection of zebrafish papp-a2 mRNA in chordamesoderm, notochord, and lower jaw of zebrafish (Danio rerio) embryos, and that papp-a2 knockdown embryos display broadened axial mesoderm, notochord bends, and severely reduced cranial cartilages. Genetic data link these phenotypes to insulin-like growth factor binding protein-3 (Igfbp-3) and Bmp signaling, and biochemical analysis show specific Igfbp-3 proteolysis by Papp-a2, implicating Papp-a2 in the modulation of Bmp signaling by Igfbp-3 proteolysis. Knockdown of papp-a2 additionally resulted in angiogenesis defects, strikingly similar to previous observations in embryos with mutations in components of the Notch system. Concordantly, we find that Notch signaling is modulated by Papp-a2 in vivo, and, furthermore, that PAPP-A2 is capable of modulating Notch signaling independently of its proteolytic activity in cell culture. Based on these results, we conclude that Papp-a2 modulates Bmp and Notch signaling by independent mechanisms in zebrafish embryos. In conclusion, these data link pappalysin function in zebrafish to two different signaling pathways outside the IGF system.
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Crosley EJ, Durland U, Seethram K, MacRae S, Gruslin A, Christians JK. First-trimester levels of pregnancy-associated plasma protein A2 (PAPP-A2) in the maternal circulation are elevated in pregnancies that subsequently develop preeclampsia. Reprod Sci 2013; 21:754-60. [PMID: 24336677 DOI: 10.1177/1933719113512532] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Recent studies have consistently found pregnancy-associated plasma protein A2 (PAPP-A2) to be upregulated in preeclamptic placentae at term. We tested whether first-trimester circulating PAPP-A2 levels differed between complicated and uncomplicated pregnancies. We measured maternal PAPP-A2 levels at 10 to 14 weeks of gestational age in 17 pregnancies resulting in small-for-gestational-age (SGA) infants, 6 which developed preeclampsia (PE), 1 which developed PE and resulted in an SGA infant, and 37 gestational age-matched controls. The concentration of the PAPP-A2 isoform corresponding to the full-length protein was significantly higher in pregnancies that developed PE (35 ng/mL) compared with those that did not (23 ng/mL; P < .044). In contrast, we found no difference in PAPP-A2 levels between pregnancies that did or did not result in an SGA infant. The upregulation of PAPP-A2 that has previously been observed in PE at term appears to begin early in pregnancy, well before the symptoms develop.
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Affiliation(s)
- Erin J Crosley
- 1Department of Biological Sciences, Simon Fraser University, Burnaby, British Columbia, Canada
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Gaidamauskas E, Gyrup C, Boldt HB, Schack VR, Overgaard MT, Laursen LS, Oxvig C. IGF dependent modulation of IGF binding protein (IGFBP) proteolysis by pregnancy-associated plasma protein-A (PAPP-A): multiple PAPP-A-IGFBP interaction sites. Biochim Biophys Acta Gen Subj 2013; 1830:2701-9. [PMID: 23671931 DOI: 10.1016/j.bbagen.2012.11.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
BACKGROUND Pregnancy-associated plasma protein-A (PAPP-A) is a local regulator of insulin-like growth factor (IGF) bioavailability in physiological systems, but many structural and functional aspects of the metzincin metalloproteinase remain to be elucidated. PAPP-A cleaves IGF binding protein (IGFBP)-4 and IGFBP-5. Cleavage of IGFBP-4, but not IGFBP-5, depends on the binding of IGF before proteolysis by PAPP-A can occur. The paralogue PAPP-A2 has two substrates among the six IGFBPs: IGFBP-3 and IGFBP-5. METHODS Sets of chimeric proteins between IGFBP-4 and -5, and IGFBP-3 and -5 were constructed to investigate the structural requirements for IGF modulation. At the proteinase level, we investigated the importance of individual acidic amino acids positioned in the proteolytic domain of PAPP-A for proteolytic activity against IGFBP-4 and -5. Interaction between PAPP-A and its substrates was analyzed by surface plasmon resonance. RESULTS AND CONCLUSION We provide data suggesting that the C-terminal domain of the IGFBPs is responsible for IGF-dependent modulation of access to the scissile bond. Loss or reduction of IGFBP proteolysis by PAPP-A was observed upon mutation of residues positioned in the unique 63-residue stretch separating the zinc and Met-turn motifs, and in the short sequence following the Met-turn methionine. A model of the proteolytic domain of PAPP-A suggests the presence of structural calcium ions in the C-terminal subdomain, implicated in IGFBP substrate interactions. GENERAL SIGNIFICANCE Detailed knowledge of interactions between PAPP-A and its substrates is required to understand the modulatory role of PAPP-A on IGF receptor stimulation.
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Affiliation(s)
- Ervinas Gaidamauskas
- Department of Molecular Biology and Genetics, University of Aarhus, DK-8000 Aarhus, Denmark
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32
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Kjaer-Sorensen K, Engholm DH, Kamei H, Morch MG, Kristensen AO, Zhou J, Conover CA, Duan C, Oxvig C. Pregnancy-associated plasma protein A (PAPP-A) modulates the early developmental rate in zebrafish independently of its proteolytic activity. J Biol Chem 2013; 288:9982-9992. [PMID: 23430244 DOI: 10.1074/jbc.m112.426304] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Pregnancy-associated plasma protein-A (PAPP-A) is a large metalloproteinase specifically cleaving insulin-like growth factor (IGF) binding proteins, causing increased IGF bioavailability and, hence, local regulation of IGF receptor activation. We have identified two highly conserved zebrafish homologs of the human PAPP-A gene. Expression of zebrafish Papp-a, one of the two paralogs, begins during gastrulation and persists throughout the first week of development, and analyses demonstrate highly conserved patterns of expression between adult zebrafish, humans, and mice. We show that the specific knockdown of zebrafish papp-a limits the developmental rate beginning during gastrulation without affecting the normal patterning of the embryo. This phenotype is different from those resulting from deficiency of Igf receptor or ligand in zebrafish, suggesting a function of Papp-a outside of the Igf system. Biochemical analysis of recombinant zebrafish Papp-a demonstrates conservation of proteolytic activity, specificity, and the intrinsic regulatory mechanism. However, in vitro transcribed mRNA, which encodes a proteolytically inactive Papp-a mutant, recues the papp-a knockdown phenotype as efficiently as wild-type Papp-a. Thus, the developmental phenotype of papp-a knockdown is not a consequence of lacking Papp-a proteolytic activity. We conclude that Papp-a possesses biological functions independent of its proteolytic activity. Our data represent the first evidence for a non-proteolytic function of PAPP-A.
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Affiliation(s)
- Kasper Kjaer-Sorensen
- Department of Molecular Biology and Genetics, Aarhus University, Gustav Wieds Vej 10C, 8000 Aarhus C, Denmark
| | - Ditte H Engholm
- Department of Molecular Biology and Genetics, Aarhus University, Gustav Wieds Vej 10C, 8000 Aarhus C, Denmark
| | - Hiroyasu Kamei
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan 48105
| | - Maria G Morch
- Department of Molecular Biology and Genetics, Aarhus University, Gustav Wieds Vej 10C, 8000 Aarhus C, Denmark
| | - Anisette O Kristensen
- Department of Molecular Biology and Genetics, Aarhus University, Gustav Wieds Vej 10C, 8000 Aarhus C, Denmark
| | - Jianfeng Zhou
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan 48105
| | - Cheryl A Conover
- Endocrine Research Unit, Mayo Clinic, Rochester, Minnesota 55905
| | - Cunming Duan
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan 48105
| | - Claus Oxvig
- Department of Molecular Biology and Genetics, Aarhus University, Gustav Wieds Vej 10C, 8000 Aarhus C, Denmark.
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Boldt HB, Bale LK, Resch ZT, Oxvig C, Overgaard MT, Conover CA. Effects of mutated pregnancy-associated plasma protein-a on atherosclerotic lesion development in mice. Endocrinology 2013; 154:246-52. [PMID: 23161866 PMCID: PMC3529381 DOI: 10.1210/en.2012-1552] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Pregnancy-associated plasma protein-A (PAPP-A) is a large multidomain metalloprotease involved in cleavage of IGF binding protein (IGFBP)-4 and -5 thereby causing release of bioactive IGF. Individual domains of PAPP-A have been characterized in vitro, including the metzincin proteolytic domain important for IGFBP proteolytic activity, short consensus repeats critical for cell surface association, and Lin-12/Notch repeat module demonstrated to determine IGFBP substrate specificity. To test the hypothesis that specific cleavage of IGFBP-4 by PAPP-A in close proximity to the cell surface is required for development of lesions in a murine model of atherosclerosis, the following PAPP-A transgenic (Tg) mice were generated: Tg(E483A), which lacks all PAPP-A proteolytic activity; Tg(D1499A), which selectively lacks proteolytic activity against IGFBP-4; and Tg(K1296A/K1316A), in which cell surface binding is compromised. Following cross-breeding with apolipoprotein E (ApoE) knockout (KO) mice, ApoE KO/Tg mice were fed a high-fat diet to promote aortic lesion development. Lesion area was increased 2-fold in aortas from ApoE KO/Tg wild-type compared with ApoE KO mice (P < 0.001). However, there was no significant increase in the lesion area in any of the ApoE KO/Tg mutant mice. We conclude that PAPP-A proteolytic activity is required for the lesion-promoting effect of PAPP-A and that its specificity must be directed against IGFBP-4. Furthermore, our data demonstrate that cleavage of IGFBP-4 at a distance from the cell surface, and hence from the IGF receptor, is not effective in promoting the development of the atherosclerotic lesions. Thus, PAPP-A exerts its effect while bound to the cell surface in vivo.
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Affiliation(s)
- Henning B Boldt
- Division of Endocrinology and Metabolism, Mayo Clinic, Rochester, MN 55905, USA
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Conover CA, Boldt HB, Bale LK, Clifton KB, Grell JA, Mader JR, Mason EJ, Powell DR. Pregnancy-associated plasma protein-A2 (PAPP-A2): tissue expression and biological consequences of gene knockout in mice. Endocrinology 2011; 152:2837-44. [PMID: 21586553 DOI: 10.1210/en.2011-0036] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Pregnancy-associated plasma protein-A2 (PAPP-A2) is a novel homolog of PAPP-A in the metzincin superfamily. However, compared with the accumulating data on PAPP-A, very little is known about PAPP-A2. In this study, we determined the tissue expression pattern of PAPP-A2 mRNA in wild-type (WT) mice and characterized the phenotype of mice with global PAPP-A2 deficiency. Tissues expressing PAPP-A2 in WT mice were more limited than those expressing PAPP-A. The highest PAPP-A2 mRNA expression was found in the placenta, with abundant expression in fetal, skeletal, and reproductive tissues. Heterozygous breeding produced the expected Mendelian distribution for the pappa2 gene and viable homozygous PAPP-A2 knockout (KO) mice that were normal size at birth. The most striking phenotype of the PAPP-A2 KO mouse was postnatal growth retardation. Male and female PAPP-A2 KO mice had 10 and 25-30% lower body weight, respectively, than WT littermates. Adult femur and body length were also reduced in PAPP-A2 KO mice, but without significant effects on bone mineral density. PAPP-A2 KO mice were fertile, but with compromised fecundity. PAPP-A expression was not altered to compensate for the loss of PAPP-A2 expression, and proteolysis of PAPP-A2's primary substrate, IGF-binding protein-5, was not altered in fibroblasts from PAPP-A2 KO embryos. In conclusion, tissue expression patterns and biological consequences of gene KO indicate distinct physiological roles for PAPP-A2 and PAPP-A in mice.
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Affiliation(s)
- Cheryl A Conover
- Endocrine Research Unit, Division of Endocrinology, Metabolism, and Nutrition, College of Medicine Mayo Clinic, 200 First Street SW, 5-194 Joseph, Rochester, Minnesota 55905, USA.
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Weyer K, Glerup S. Placental Regulation of Peptide Hormone and Growth Factor Activity by proMBP1. Biol Reprod 2011; 84:1077-86. [DOI: 10.1095/biolreprod.110.090209] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
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36
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Christians JK, Gruslin A. Altered levels of insulin-like growth factor binding protein proteases in preeclampsia and intrauterine growth restriction. Prenat Diagn 2010; 30:815-20. [PMID: 20658698 DOI: 10.1002/pd.2583] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Intrauterine growth restriction (IUGR) and preeclampsia (PE) are leading causes of perinatal and maternal morbidity and mortality. Many studies have found association between low levels of insulin-like growth factor binding protein (IGFBP) proteases in the first trimester maternal circulation and the risk of subsequent development of PE and/or IUGR. These results are generally interpreted to reflect decreased production of the proteases by the placenta, leading to reduced proteolysis of IGFBPs and lower free levels of insulin-like growth factor (IGF), resulting in diminished feto-placental development. However, the association between low circulating levels of placental proteins early in pregnancy and the subsequent development of IUGR and/or PE could be due to low exchange in the placenta and not due to reduced production. In contrast, late in pregnancy, the circulating levels of these proteins and their expression in the placenta are often elevated in PE, which may reflect upregulation to compensate for abnormal placental development, that is an adaptive mechanism to increase IGFBP proteolysis, increase local IGF levels and promote feto-placental growth. Further research into the biological mechanisms underlying these associations will aid the identification of high-risk pregnancies and the development of therapeutic targets for diseases for which there are presently no preventative measures.
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37
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Pregnancy-associated plasma protein-A in the pathophysiology, diagnosis, and prognosis of coronary heart disease. COR ET VASA 2010. [DOI: 10.33678/cor.2010.120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Abstract
Cell–cell signaling mediated by the Notch receptor is iteratively involved in numerous developmental contexts, and its dysregulation has been associated with inherited genetic disorders and cancers. The core components of the signaling pathway have been identified for some time, but the study of the modulation of the pathway in different cellular contexts has revealed many layers of regulation. These include complex sugar modifications in the extracellular domain as well as transit of Notch through defined cellular compartments, including specific endosomes.
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Affiliation(s)
- An-Chi Tien
- Program in Developmental Biology, Baylor College of Medicine, Houston, TX 77030, USA
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Tien AC, Rajan A, Schulze KL, Ryoo HD, Acar M, Steller H, Bellen HJ. Ero1L, a thiol oxidase, is required for Notch signaling through cysteine bridge formation of the Lin12-Notch repeats in Drosophila melanogaster. ACTA ACUST UNITED AC 2008; 182:1113-25. [PMID: 18809725 PMCID: PMC2542473 DOI: 10.1083/jcb.200805001] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Notch-mediated cell–cell communication regulates numerous developmental processes and cell fate decisions. Through a mosaic genetic screen in Drosophila melanogaster, we identified a role in Notch signaling for a conserved thiol oxidase, endoplasmic reticulum (ER) oxidoreductin 1–like (Ero1L). Although Ero1L is reported to play a widespread role in protein folding in yeast, in flies Ero1L mutant clones show specific defects in lateral inhibition and inductive signaling, two characteristic processes regulated by Notch signaling. Ero1L mutant cells accumulate high levels of Notch protein in the ER and induce the unfolded protein response, suggesting that Notch is misfolded and fails to be exported from the ER. Biochemical assays demonstrate that Ero1L is required for formation of disulfide bonds of three Lin12-Notch repeats (LNRs) present in the extracellular domain of Notch. These LNRs are unique to the Notch family of proteins. Therefore, we have uncovered an unexpected requirement for Ero1L in the maturation of the Notch receptor.
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Affiliation(s)
- An-Chi Tien
- Program in Developmental Biology, Baylor College of Medicine, Houston, TX 77030, USA
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40
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Mikkelsen JH, Gyrup C, Kristensen P, Overgaard MT, Poulsen CB, Laursen LS, Oxvig C. Inhibition of the proteolytic activity of pregnancy-associated plasma protein-A by targeting substrate exosite binding. J Biol Chem 2008; 283:16772-80. [PMID: 18434323 DOI: 10.1074/jbc.m802429200] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The metalloproteinase pregnancy-associated plasma protein-A (PAPP-A) cleaves both insulin-like growth factor (IGF)-binding protein 4 (IGFBP-4) and -5 at a single site in their central domain causing the release of bioactive IGF. Inhibition of IGF signaling is relevant in human disease, and several drugs in development target the IGF receptor. However, inhibition of PAPP-A activity may be a valuable alternative. We have generated monoclonal phage-derived single chain fragment variable (scFv) antibodies which selectively inhibit the cleavage of IGFBP-4 by PAPP-A, relevant under conditions where cleavage of IGFBP-4 represents the final step in the delivery of IGF to the IGF receptor. None of the antibodies inhibited the homologous proteinase PAPP-A2, which allowed mapping of antibody binding by means of chimeras between PAPP-A and PAPP-A2 to the C-terminal Lin12-Notch repeat module, separated from the proteolytic domain by almost 1000 amino acids. Hence, the antibodies define a substrate binding exosite that can be targeted for the selective inhibition of PAPP-A proteolytic activity against IGFBP-4. In addition, we show that the Lin12-Notch repeat module reversibly binds a calcium ion and that bound calcium is required for antibody binding, providing a strategy for the further development of selective inhibitory compounds. To our knowledge these data represent the first example of differential inhibition of cleavage of natural proteinase substrates by exosite targeting. Generally, exosite inhibitors are less likely to affect the activity of related proteolytic enzymes with similar active site environments. In the case of PAPP-A, selective inhibition of IGFBP-4 cleavage by interference with exosite binding is a further advantage, as the activity against other known or unknown PAPP-A substrates, whose cleavage may not depend on binding to the same exosite, is not targeted.
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Affiliation(s)
- Jakob H Mikkelsen
- Department of Molecular Biology, University of Aarhus, DK-8000 Aarhus, Denmark
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41
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Tallant C, García-Castellanos R, Marrero A, Canals F, Yang Y, Reymond JL, Solà M, Baumann U, Gomis-Rüth FX. Activity of ulilysin, an archaeal PAPP-A-related gelatinase and IGFBP protease. Biol Chem 2008; 388:1243-53. [PMID: 17976018 DOI: 10.1515/bc.2007.143] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Human growth and development are conditioned by insulin-like growth factors (IGFs), which have also implications in pathology. Most IGF molecules are sequestered by IGF-binding proteins (IGFBPs) so that exertion of IGF activity requires disturbance of these complexes. This is achieved by proteolysis mediated by IGFBP proteases, among which the best characterised is human PAPP-A, the first member of the pappalysin family of metzincins. We have previously identified and studied the only archaeal homologue found to date, Methanosarcina acetivorans ulilysin. This is a proteolytically functional enzyme encompassing a pappalysin catalytic domain and a pro-domain involved in maintenance of latency of the zymogen, proulilysin. Once activated, the protein hydrolyses IGFBP-2 to -6 and insulin chain beta in vitro. We report here that ulilysin is also active against several other substrates, viz (azo)casein, azoalbumin, and extracellular matrix components. Ulilysin has gelatinolytic but not collagenolytic activity. Moreover, the proteolysis-resistant skeletal proteins actin and elastin are also cleaved, as is fibrinogen, but not plasmin and alpha1-antitrypsin from the blood coagulation cascade. Ulilysin develops optimal activity at pH 7.5 and strictly requires peptide bonds preceding an arginine residue, as determined by means of a novel fluorescence resonance energy transfer assay, thus pointing to biotechnological applications as an enzyme complementary to trypsin.
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Affiliation(s)
- Cynthia Tallant
- Departament de Biologia Estructural, Institut de Biologia Molecular de Barcelona, CSIC, c/ Jordi Girona, 18-26, E-08034, Barcelona, Spain
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42
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Chen T, Hogan S, Conley G, Pazmany C, Wu QL, McNeil GL, Bassill G, Macintyre AN, Martik D, Nixon AE, Sexton DJ. Discovery and characterization of human antibody inhibitors of pregnancy-associated plasma protein-A. Biol Chem 2007; 388:507-12. [PMID: 17516846 DOI: 10.1515/bc.2007.058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abstract
Pregnancy-associated plasma protein-A (PAPP-A) is a metalloprotease that cleaves insulin-like growth factor-binding proteins (IGFBPs) to release bioactive levels of free insulin-like growth factor. Specific and potent inhibitors of PAPP-A may further elucidate the biological functions of this protease and could prove to be of therapeutic value. Phage display was used to discover fully human antibody inhibitors of PAPP-A activity towards IGFBP4 cleavage. Estimates of the inhibition constants for these antibodies were subsequently determined using a novel continuous assay of PAPP-A protease activity that uses an internally quenched synthetic peptide substrate (DX-1655). DX-1655 was hydrolyzed by PAPP-A with a K
m of 33 μM and a k
cat of 0.3 s-1 (k
cat/K
m=9.1×103 M-1 s-1). PAPP-A activity towards DX-1655 displays a bell-shaped pH profile, with pK
a values of 8.2 and 10.8 and a maximum rate at approximately pH 9.5. Using this continuous assay, we measured apparent K
i values of 1.7±0.2 and 7.4±1.5 nM for the F2 and D9 antibodies, respectively.
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Affiliation(s)
- Ting Chen
- Dyax Corp, 300 Technology Square, Cambridge, MA 02139, USA
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43
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Qin QP, Wittfooth S, Pettersson K. Measurement and clinical significance of circulating PAPP-A in ACS patients. Clin Chim Acta 2007; 380:59-67. [PMID: 17376420 DOI: 10.1016/j.cca.2007.02.036] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2006] [Revised: 02/08/2007] [Accepted: 02/17/2007] [Indexed: 11/19/2022]
Abstract
BACKGROUND The rupture of coronary atherosclerotic plaque and subsequent thrombus formation are major events underlying acute coronary syndromes (ACS). Pregnancy associated plasma protein A (PAPP-A), a biomarker of plaque rupture, has been studied in patients with ACS. This review aimed to provide an overview of clinical utility of PAPP-A in ACS patients and analytical issues adhering to immunological PAPP-A measurement. METHODS The literature relating to PAPP-A in ACS, the molecular structure and immunodetection of PAPP-A was reviewed. PubMed was used to search the relevant articles published from 1974 to 2006. RESULTS Higher PAPP-A concentrations have been found in patients with ACS than in patients with stable angina and subjects without coronary artery disease. Elevated PAPP-A concentrations have also been shown to associate with adverse cardiac events in ACS patients. The prognostic value of PAPP-A appears to be independent of cardiac troponins. Noteworthy, the PAPP-A form that accounts for increase in ACS is uncomplexed with the proform of eosinophil major basic protein (proMBP). However, PAPP-A assays applied in clinical studies published thus far detect total PAPP-A. Consequently, the clinical value may be non-optimal when total PAPP-A is measured in ACS patients. In addition, the clinical value can also be affected by the analytical factors that exert an effect on the performance of PAPP-A assays. CONCLUSIONS PAPP-A appears to be a very promising biomarker useful in the clinical management of ACS patients. However, more prospective and interventional studies with carefully established immunoassays are required to validate its clinical utility.
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Affiliation(s)
- Qiu-Ping Qin
- Innotrac Diagnostics, Biolinja 12, 20750 Turku, Finland.
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44
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Weyer K, Boldt HB, Poulsen CB, Kjaer-Sorensen K, Gyrup C, Oxvig C. A substrate specificity-determining unit of three Lin12-Notch repeat modules is formed in trans within the pappalysin-1 dimer and requires a sequence stretch C-terminal to the third module. J Biol Chem 2007; 282:10988-99. [PMID: 17314100 DOI: 10.1074/jbc.m607903200] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Members of the pappalysin family of metzincin metalloproteinases, pregnancy-associated plasma protein-A (PAPP-A, pappalysin-1) and PAPP-A2 (pappalysin-2), regulate the bioavailability of insulin-like growth factors (IGFs) by specific proteolytic inactivation of IGF-binding proteins (IGFBPs). PAPP-A cleaves IGFBP-4 and IGFBP-5, whereas PAPP-A2 cleaves only IGFBP-5. The pappalysins contain three Lin12-Notch repeat (LNR1-3) modules, previously considered unique to the Notch receptor family in which they function to regulate receptor cleavage. In contrast to the Notch receptor where three LNR modules are tandemly arranged, LNR3 is separated by more than 1000 residues from LNR1-2 in the pappalysin sequence. Each of the three LNR modules of PAPP-A is required for proteolysis of IGFBP-4, but not IGFBP-5. However, we here find that a C-terminal truncated variant of PAPP-A, which lacks LNR3 and therefore activity against IGFBP-4, cleaves IGFBP-4 when co-expressed with a PAPP-A variant, which is mutated in the active site. This suggests that LNR3 from the inactive subunit interacts in trans with LNR1-2 of the truncated PAPP-A subunit to form a functional trimeric LNR unit. We also show that formation of such a functional LNR unit depends on dimerization, as dissociation of a mutated non-covalent PAPP-A dimer results in reduced activity against IGFBP-4, but not IGFBP-5. Using PAPP-A/PAPP-A2 chimeras, we demonstrate that PAPP-A2 LNR1-2, but not LNR3, are functionally conserved with respect to IGFBP proteolysis. Additionally, we find that a sequence stretch C-terminal to LNR3 and single residues (Asp1521, Arg1529, and Asp1530) within this are required for LNR functionality.
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Affiliation(s)
- Kathrin Weyer
- Department of Molecular Biology, University of Aarhus, Aarhus DK-8000, Denmark
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45
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Overall CM, Blobel CP. In search of partners: linking extracellular proteases to substrates. Nat Rev Mol Cell Biol 2007; 8:245-57. [PMID: 17299501 DOI: 10.1038/nrm2120] [Citation(s) in RCA: 257] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Proteases function as molecular switches in signalling circuits at the cell surface and in the extracellular milieu. In light of the many proteases that are encoded by the genome, and the even larger number of bioactive substrates, it is crucial to identify which proteases cleave a particular substrate and which substrates individual proteases cleave. Elucidating the substrate degradomes of proteases will help us to understand the function of proteases in development and disease and to validate proteases as drug targets.
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Affiliation(s)
- Christopher M Overall
- The UBC Centre for Blood Research, CBCRA Program in Breast Cancer Metastasis, Department of Oral Biological & Medical Sciences, University of British Columbia, 4.401 Life Sciences Center, Vancouver, British Columbia, V6T 1Z3, Canada
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46
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Boldt HB, Conover CA. Pregnancy-associated plasma protein-A (PAPP-A): a local regulator of IGF bioavailability through cleavage of IGFBPs. Growth Horm IGF Res 2007; 17:10-18. [PMID: 17218136 DOI: 10.1016/j.ghir.2006.11.003] [Citation(s) in RCA: 135] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Pregnancy-associated plasma protein-A (PAPP-A) was originally isolated in 1974, as one of four proteins of placental origin found in high concentrations in the blood of pregnant women. In the early 1990s several laboratories reported novel protease activity against insulin-like growth factor binding protein-4 (IGFBP-4) in media conditioned by several cell types. This activity was unique, as it appeared to require the presence of IGF to cleave IGFBP-4. In 1999, this IGF-dependent IGFBP-4 protease activity was isolated from human fibroblast conditioned media and identified as PAPP-A. Subsequently, PAPP-A was shown to be expressed by a variety of cell types, and thus no longer could be considered to be just "pregnancy-associated". This review will describe what is currently known about the structure of PAPP-A and about its function as an IGFBP protease, with a focus on new insights obtained through study of a PAPP-A knock-out mouse model and on potential clinical applications.
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Affiliation(s)
- Henning B Boldt
- Division of Endocrinology, Metabolism, and Nutrition, Department of Internal Medicine, Mayo Clinic College of Medicine, 200 First Street SW, 5-194 Joseph, Rochester, MN 55905, USA
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47
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García-Castellanos R, Tallant C, Marrero A, Solà M, Baumann U, Gomis-Rüth FX. Substrate specificity of a metalloprotease of the pappalysin family revealed by an inhibitor and a product complex. Arch Biochem Biophys 2006; 457:57-72. [PMID: 17097044 DOI: 10.1016/j.abb.2006.10.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2006] [Revised: 10/02/2006] [Accepted: 10/03/2006] [Indexed: 10/24/2022]
Abstract
Human pappalysin-1 is a multi-domain metalloprotease engaged in the homeostasis of insulin-like growth factors and the founding member of the pappalysin family within the metzincin clan of metalloproteases. We have recently identified an archaeal relative, ulilysin, encompassing only the protease domain. It is a 262-residue active protease with a novel 3D structure with two subdomains separated by an active-site cleft. Despite negligible overall sequence similarity, noticeable similarity is found with other metzincin prototypes, adamalysins/ADAMs and matrix metalloproteinases. Ulilysin has been crystallised in a product complex with an arginine-valine dipeptide occupying the active-site S(1') and S(2') positions and in a complex with the broad-spectrum hydroxamic acid-based metalloprotease inhibitor, batimastat. This molecule inhibits mature ulilysin with an IC(50) value of 61 microM under the conditions assayed. The binding of batimastat to ulilysin evokes binding to vertebrate matrix metalloproteases but is much weaker. These data give insight into substrate specificity and mechanism of action and inhibition of the novel pappalysin family.
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Affiliation(s)
- Raquel García-Castellanos
- Departament de Biologia Estructural, Institut de Biologia Molecular de Barcelona, CSIC, c/Jordi Girona, 18-26, E-08034 Barcelona, Spain
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48
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Tallant C, García-Castellanos R, Seco J, Baumann U, Gomis-Rüth FX. Molecular Analysis of Ulilysin, the Structural Prototype of a New Family of Metzincin Metalloproteases. J Biol Chem 2006; 281:17920-8. [PMID: 16627477 DOI: 10.1074/jbc.m600907200] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
The metzincin clan encompasses several families of zinc-dependent metalloproteases with proven function both in physiology and pathology. They act either as broad spectrum protein degraders or as sheddases, operating through limited proteolysis. Among the structurally uncharacterized metzincin families are the pappalysins, of which the most thoroughly studied member is human pregnancy-associated plasma protein A (PAPP-A), a heavily glycosylated 170-kDa multidomain protein specifically cleaving insulin-like growth factor (IGF)-binding proteins (IGFBPs). Proulilysin is a 38-kDa archaeal protein that shares sequence similarity with PAPP-A but encompasses only the pro-domain and the catalytic domain. It undergoes calcium-mediated autolytic activation, and the mature protein adopts a three-dimensional structure with two subdomains separated by an active site cleft containing the catalytic zinc ion. This structure is reminiscent of human members of the adamalysin/ADAMs (a disintegrin and a metalloprotease) family of metzincins. A bound dipeptide yields information on the substrate specificity of ulilysin, which specifically hydrolyzes IGFBP-2 to -6, insulin, and extracellular matrix proteins but not IGFBP-1 or IGF-II. Accordingly, ulilysin has higher proteolytic efficiency and a broader substrate specificity than human PAPP-A. The structure of ulilysin represents a prototype for the catalytic domain of pappalysins.
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Affiliation(s)
- Cynthia Tallant
- Departament de Biologia Estructural, Institut de Biologia Molecular de Barcelona, Consejo Superior de Investigaciones Científicas, c/Jordi Girona 18-26, E-08034 Barcelona, Spain
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49
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Christians JK, Hoeflich A, Keightley PD. PAPPA2, an enzyme that cleaves an insulin-like growth-factor-binding protein, is a candidate gene for a quantitative trait locus affecting body size in mice. Genetics 2006; 173:1547-53. [PMID: 16702428 PMCID: PMC1526668 DOI: 10.1534/genetics.106.057513] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Identifying genes responsible for quantitative variation remains a major challenge. We previously identified a quantitative trait locus (QTL) affecting body size that segregated between two inbred strains of mice. By fine mapping, we have refined the location of this QTL to a genomic region containing only four protein-coding genes. One of these genes, PAPPA2, is a strong candidate because it codes for an enzyme that cleaves insulin-like growth-factor-binding protein 5 (IGFBP-5), an important stimulator of bone formation. Among littermates that segregate only for the four-gene region, we show that the QTL has a significant effect on the circulating levels of IGFBP-5 and IGFBP-3 (the latter subject to limited degradation by PAPPA2), but not on levels of IGFBP-2 and IGFBP-4, which are not cleaved by PAPPA2. There are 14 nonsynonymous SNPs among QTL alleles, which may affect the activity of the translated protein. The refinement of the target region to four genes and the finding that the QTL affects IGFBP-5 levels suggest that PAPPA2 may be involved with normal postnatal growth. Our mapping results also illustrate the potentially fractal nature of QTL: as we mapped our QTL with increasing resolution, what appeared to be a single QTL resolved into three closely linked QTL (previous work), and then one of these was further dissected into two in this study.
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Affiliation(s)
- Julian K Christians
- University of Edinburgh Institute of Evolutionary Biology, School of Biological Sciences, United Kingdom.
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