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Judge RA, Sridar J, Tunyasunvunakool 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: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [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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Windsperger K, Dekan S, Pils S, Golletz C, Kunihs V, Fiala C, Kristiansen G, Knöfler M, Pollheimer J. Extravillous trophoblast invasion of venous as well as lymphatic vessels is altered in idiopathic, recurrent, spontaneous abortions. Hum Reprod 2017; 32:1208-1217. [DOI: 10.1093/humrep/dex058] [Citation(s) in RCA: 63] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2017] [Accepted: 03/07/2017] [Indexed: 12/11/2022] Open
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3
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Brockmann EC, Akter S, Savukoski T, Huovinen T, Lehmusvuori A, Leivo J, Saavalainen O, Azhayev A, Lövgren T, Hellman J, Lamminmäki U. Synthetic single-framework antibody library integrated with rapid affinity maturation by VL shuffling. Protein Eng Des Sel 2011; 24:691-700. [PMID: 21680620 DOI: 10.1093/protein/gzr023] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Affinity maturation is often applied to improve the properties of antibodies isolated from universal antibody libraries in vitro. A synthetic human scFv antibody library was constructed in single immunoglobulin framework to enable rapid affinity maturation by updated Kunkel's mutagenesis. The initial diversity was generated predominantly in the V(H) domain combined with only 36 V(L) domain variants yielding 3 × 10(10) unique members in the phage-displayed library. After three rounds of panning the enriched V(H) genes from the primary library selections against lysozyme were incorporated into a ready-made circular single-stranded affinity maturation library containing 7 × 10(8) V(L) gene variants. Several unique antibodies with 0.8-10 nM (K(d), dissociation constant) affinities against lysozyme were found after panning from the affinity maturation library, contrasted by only one anti-lysozyme scFv clone with K(d) <20 nM among the clones panned from the primary universal library. The presented single-framework strategy provides a way to convey significant amount of functional V(H) domain diversity to affinity maturation without bimolecular ligation leading to a diverse set of antibodies with binding affinities in the low nanomolar range.
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Affiliation(s)
- E-C Brockmann
- Department of Biotechnology, University of Turku, Turku, Finland.
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4
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Phang D, Rehage M, Bonafede B, Hou D, Xing W, Mohan S, Wergedal JE, Qin X. Inactivation of insulin-like-growth factors diminished the anabolic effects of pregnancy-associated plasma protein-A (PAPP-A) on bone in mice. Growth Horm IGF Res 2010; 20:192-200. [PMID: 20144555 DOI: 10.1016/j.ghir.2010.01.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/13/2009] [Revised: 01/06/2010] [Accepted: 01/12/2010] [Indexed: 11/16/2022]
Abstract
In vivo studies have provided ubiquitous evidence that pregnancy-associated plasma protein-A (PAPP-A) functions as a potent anabolic factor. While some evidence supports the prediction that increasing IGF bioavailability contributes to the anabolic effects of PAPP-A, definitive evidence has been lacking. This important issue has been addressed in this study using a unique mouse model in which PAPP-A was overexpressed in bone either alone or together with a protease-resistant IGFBP-4 analog (PRBP-4) which serves as an IGF inhibitor. PAPP-A transgenic mice exhibited a 25% increase in skull bone mineral density (BMD) whereas PRBP-4 transgenic mice showed a 20-25% decrease in this parameter at an age of 3months. Femur/tibia size-related parameters were significantly increased in PAPP-A transgenic mice but decreased in PRBP-4 transgenic mice. This data clearly demonstrates that PAPP-A transgenic mice exhibit opposite phenotypes in both flat bone and long bone compared to PRBP-4 transgenic mice which have reduced IGF bioavailability in bone. Importantly, PRBP-4 and PRBP-4/PAPP-A double transgenic mice shared essentially identical phenotypes in both flat and long bones. Calvarial thickness, skull BMD and long bone parameters were reduced to similar degrees in PRBP-4 and PRBP-4/PAPP-A transgenic mice relative to wild-type littermates. Our findings provide compelling evidence that PAPP-A increases bone formation primarily by increasing IGF bioavailability and that other alternative pathways may play a negligible role in mediating the anabolic effect of PAPPA in bone. This clear definition of PAPP-A's mechanism of action is critical for future translational studies on the therapeutic application of PAPP-A.
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Affiliation(s)
- David Phang
- Musculoskeletal Disease Center, Loma Linda University, Loma Linda, CA 92354, United States
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Rehage M, Mohan S, Wergedal JE, Bonafede B, Tran K, Hou D, Phang D, Kumar A, Qin X. Transgenic overexpression of pregnancy-associated plasma protein-A increases the somatic growth and skeletal muscle mass in mice. Endocrinology 2007; 148:6176-85. [PMID: 17901236 DOI: 10.1210/en.2007-0274] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Although IGFs are indispensable to skeletal muscle development, little information is available regarding the mechanisms regulating the local action of IGFs in skeletal muscle tissues. Here we tested the hypothesis that pregnancy-associated plasma protein-A (PAPP-A), a member of the metalloproteinase superfamily, promotes skeletal muscle formation in vivo through degrading IGF binding proteins (IGFBPs), which increases the bioavailability of IGFs. Expression of PAPP-A is significantly increased in muscle five days after muscle injury in mice. Targeted overexpression of PAPP-A using a muscle-specific promoter significantly increased the prenatal/postnatal growth, skeletal muscle weight, and muscle fiber area in mice. These anabolic effects were reproduced using F2/F3 progeny. Free IGF-I concentration was severalfold higher in the conditioned medium (CM) of ex vivo cultured muscle from the transgenic mice, compared with the wild-type littermate muscle. Accordingly, the proliferation of C2C12 myoblasts was significantly increased in the presence of CM from cultured skeletal muscle of the transgenic mice, compared with the controls. This observed increase in myoblast proliferation was abolished on addition of noncleavable IGFBP-4 peptide, which reduced free IGF-I concentration back to the basal level of the wild-type CM. Furthermore, proliferation and differentiation of C2C12 myoblasts was increased by transient overexpression of proteolytically active PAPP-A but not by inactive mutant PAPP-A (E483/A). Collectively, we identified PAPP-A as a novel regulator of prenatal/postnatal growth and skeletal muscle formation in vivo. Moreover, our studies provide the first experimental evidence that IGFBP degradation is a key determinant in modulating the local action of IGFs in muscle.
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Affiliation(s)
- Mark Rehage
- Musculoskeletal Disease Center, J. L. Pettis Veterans Affairs Medical Center (151), 11201 Benton Street, Loma Linda, CA 92357, USA
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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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Qin X, Wergedal JE, Rehage M, Tran K, Newton J, Lam P, Baylink DJ, Mohan S. Pregnancy-associated plasma protein-A increases osteoblast proliferation in vitro and bone formation in vivo. Endocrinology 2006; 147:5653-61. [PMID: 16946002 PMCID: PMC2904517 DOI: 10.1210/en.2006-1055] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.2] [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 (PAPP)-A, a protease for IGF binding protein (IGFBP)-2, -4, and -5, may enhance IGF action by increasing its bioavailability. Here we have determined the role and mechanism of action of PAPP-A in the regulation of osteoblast proliferation in vitro and bone metabolism in vivo. Recombinant PAPP-A (100 ng/ml) significantly increased osteoblast proliferation and free IGF-I concentration. These effects were abolished by noncleavable IGFBP-4, suggesting that PAPP-A promotes osteoblast proliferation by increasing IGF bioavailability. To determine whether PAPP-A exerts an anabolic effect on bone in vivo, we developed transgenic mice that overexpress PAPP-A in osteoblasts using the 2.3-kb rat type I collagen promoter. Consistent with the increase in IGFBP-4 proteolysis, free IGF-I concentration was significantly increased in the conditioned medium of cultured osteoblasts derived from transgenic mice compared with the wild-type littermates. Calvarial bone thickness, bone marrow cavity, and skull bone mineral density were significantly increased in transgenic mice. Bone size-related parameters in femur and tibia such as total bone area and periosteal circumference as determined by peripheral quantitated computed tomography and histological analysis were significantly increased in transgenic mice. Bone formation rate and osteoid surface were increased by more than 2-fold, whereas bone resorbing surface was unaffected. These anabolic effects were sustained with aging. These findings provide strong evidence that PAPP-A acts as a potent anabolic factor in the regulation of bone formation. Thus, enhancing IGF bioavailability by PAPP-A can be a powerful strategy in the treatment of certain metabolic diseases such as osteoporosis.
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Affiliation(s)
- Xuezhong Qin
- Musculoskeletal Disease Center, J. L. Pettis Veterans Affairs Medical Center (151), 11201 Benton Street, and Department of Medicine, Loma Linda University, California 92357, USA.
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Qin QP, Kokkala S, Lund J, Tamm N, Qin X, Lepäntalo M, Pettersson K. Immunoassays Developed for Pregnancy-Associated Plasma Protein-A (PAPP-A) in Pregnancy May Not Recognize PAPP-A in Acute Coronary Syndromes. Clin Chem 2006; 52:398-404. [PMID: 16423908 DOI: 10.1373/clinchem.2005.058396] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
AbstractBackground: Pregnancy-associated plasma protein-A (PAPP-A) concentrations are increased in the circulation of patients with acute coronary syndromes (ACS) and are associated with future adverse cardiac events. PAPP-A in ACS differs from PAPP-A in pregnancy in that PAPP-A in ACS is not complexed with the proform of eosinophil major basic protein (proMBP). We investigated the effect of antibody selection on the utility of PAPP-A assays for measurement of PAPP-A in pregnancy and/or ACS, and whether immunoassays for PAPP-A in pregnancy are suitable for PAPP-A in ACS.Methods: We constructed 2-site sandwich time-resolved immunofluorometric assays using 22 monoclonal antibodies raised against pregnancy serum PAPP-A. All antibodies were studied in pairs, with each antibody used as either capture or tracer. We compared the reactivity of each antibody combination with PAPP-A/proMBP complex derived from pregnancy sera or with uncomplexed PAPP-A extracted from atherosclerotic plaques. Recombinant human PAPP-A and proMBP were also used to determine the specificity of the antibodies. We confirmed all major findings with serum samples collected from patients with myocardial infarction.Results: Six monoclonal antibodies reacted with the proMBP subunit of the PAPP-A/proMBP complex. Epitopes of 3 proMBP-reactive antibodies largely overlapped, but were well separated from those of another group of 3 proMBP-reactive antibodies. Assays using any of the 6 proMBP-reactive antibodies failed to detect PAPP-A in ACS. In addition, some 2-site assays capable of detecting PAPP-A in pregnancy were almost incapable of detecting PAPP-A in ACS, although the individual epitopes remained detectable in PAPP-A in ACS.Conclusions: Immunoassays developed for PAPP-A in pregnancy may not be suitable for PAPP-A in ACS. Assays for PAPP-A in ACS should be based on careful antibody selection and subjected to extensive testing with clinical ACS samples.
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Affiliation(s)
- Qiu-Ping Qin
- Department of Biotechnology, University of Turku, Turku, Finland.
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Kumar A, Mohan S, Newton J, Rehage M, Tran K, Baylink DJ, Qin X. Pregnancy-associated plasma protein-A regulates myoblast proliferation and differentiation through an insulin-like growth factor-dependent mechanism. J Biol Chem 2005; 280:37782-9. [PMID: 16115888 PMCID: PMC2902990 DOI: 10.1074/jbc.m505278200] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Pregnancy-associated plasma protein-A (PAPP-A), a member of the metalloproteinase superfamily, is an important regulator of mammalian growth and development. However, the role of PAPP-A and its mechanism of action in various cellular processes remain unknown. In this study, we have investigated the role of PAPP-A in skeletal myogenesis using C2C12 myoblasts. Recombinant PAPP-A was purified from the conditioned medium of HT1080 cells overexpressing PAPP-A. Treatment of C2C12 myoblasts with PAPP-A increased their proliferation in a dose- and time-dependent manner. Addition of exogenous PAPP-A also increased the myotube formation and the activity of creatine kinase in C2C12 cultures. Transient overexpression of the full-length PAPP-A-(1-1547), but not truncated protease-inactive N-terminal PAPP-A-(1-920) or C-terminal PAPP-A-(1100-1547), significantly enhanced the proliferation of C2C12 myoblasts. In vitro and in situ experiments demonstrated that PAPP-A cleaves insulin-like growth factor-binding protein (IGFBP)-2, but not IGFBP-3, in the conditioned medium of C2C12 myoblasts. Overexpression of PAPP-A led to degradation of the IGFBP-2 produced by C2C12 myoblasts and increased free IGF-I concentrations without affecting total IGF-I concentrations. Addition of protease-resistant IGFBP-4 completely abolished the PAPP-A-induced proliferation of C2C12 myoblasts. Our results demonstrate that 1) PAPP-A increases the proliferation and differentiation of myoblasts, 2) the stimulatory effect of PAPP-A on myogenesis is governed by its proteolytic activity, and 3) PAPP-A promotes skeletal myogenesis by increasing the amount of free IGFs via specific degradation of IGFBP-2 produced by myoblasts.
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Affiliation(s)
- Ashok Kumar
- Musculoskeletal Disease Center, J. L. Pettis Memorial Veterans Affairs Medical Center, Loma Linda University, Loma Linda, California 92357
- Department of Medicine, Loma Linda University, Loma Linda, California 92357
| | - Subburaman Mohan
- Musculoskeletal Disease Center, J. L. Pettis Memorial Veterans Affairs Medical Center, Loma Linda University, Loma Linda, California 92357
- Department of Medicine, Loma Linda University, Loma Linda, California 92357
- Department of Biochemistry, Loma Linda University, Loma Linda, California 92357
- Department of Physiology, Loma Linda University, Loma Linda, California 92357
| | - Jacqueline Newton
- Musculoskeletal Disease Center, J. L. Pettis Memorial Veterans Affairs Medical Center, Loma Linda University, Loma Linda, California 92357
| | - Mark Rehage
- Musculoskeletal Disease Center, J. L. Pettis Memorial Veterans Affairs Medical Center, Loma Linda University, Loma Linda, California 92357
| | - Kiet Tran
- Musculoskeletal Disease Center, J. L. Pettis Memorial Veterans Affairs Medical Center, Loma Linda University, Loma Linda, California 92357
| | - David J. Baylink
- Musculoskeletal Disease Center, J. L. Pettis Memorial Veterans Affairs Medical Center, Loma Linda University, Loma Linda, California 92357
- Department of Medicine, Loma Linda University, Loma Linda, California 92357
- Department of Biochemistry, Loma Linda University, Loma Linda, California 92357
| | - Xuezhong Qin
- Musculoskeletal Disease Center, J. L. Pettis Memorial Veterans Affairs Medical Center, Loma Linda University, Loma Linda, California 92357
- Department of Medicine, Loma Linda University, Loma Linda, California 92357
- To whom correspondence should be addressed: Musculoskeletal Disease Center, J. L. Pettis Veterans Affairs Medical Center (151), 11201 Benton St., Loma Linda, CA 92357. Tel.: 909-825-7084 (ext. 2773); Fax: 909-796-1680;
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