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BMP3 inhibits TGFβ2-mediated myofibroblast differentiation during wound healing of the embryonic cornea. NPJ Regen Med 2022; 7:36. [PMID: 35879352 PMCID: PMC9314337 DOI: 10.1038/s41536-022-00232-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Accepted: 07/06/2022] [Indexed: 11/29/2022] Open
Abstract
Often acute damage to the cornea initiates drastic tissue remodeling, resulting in fibrotic scarring that disrupts light transmission and precedes vision impairment. Very little is known about the factors that can mitigate fibrosis and promote scar-free cornea wound healing. We previously described transient myofibroblast differentiation during non-fibrotic repair in an embryonic cornea injury model. Here, we sought to elucidate the mechanistic regulation of myofibroblast differentiation during embryonic cornea wound healing. We found that alpha-smooth muscle actin (αSMA)-positive myofibroblasts are superficial and their presence inversely correlates with wound closure. Expression of TGFβ2 and nuclear localization of pSMAD2 were elevated during myofibroblast induction. BMP3 and BMP7 were localized in the corneal epithelium and corresponded with pSMAD1/5/8 activation and absence of myofibroblasts in the healing stroma. In vitro analyses with corneal fibroblasts revealed that BMP3 inhibits the persistence of TGFβ2-induced myofibroblasts by promoting disassembly of focal adhesions and αSMA fibers. This was confirmed by the expression of vinculin and pFAK. Together, these data highlight a mechanism to inhibit myofibroblast persistence during cornea wound repair.
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2
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Type II BMP and activin receptors BMPR2 and ACVR2A share a conserved mode of growth factor recognition. J Biol Chem 2022; 298:102076. [PMID: 35643319 PMCID: PMC9234707 DOI: 10.1016/j.jbc.2022.102076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Revised: 05/23/2022] [Accepted: 05/24/2022] [Indexed: 11/21/2022] Open
Abstract
BMPR2 is a type II Transforming Growth Factor (TGF)-β family receptor that is fundamentally associated with pulmonary arterial hypertension (PAH) in humans. BMPR2 shares functional similarities with the type II activin receptors ACVR2A and ACVR2B, as it interacts with an overlapping group of TGF-β family growth factors (GFs). However, how BMPR2 recognizes GFs remains poorly understood. Here, we solved crystal structures of BMPR2 in complex with the GF activin B and of ACVR2A in complex with the related GF activin A. We show that both BMPR2 and ACVR2A bind GFs with nearly identical geometry using a conserved hydrophobic hot spot, while differences in contacting residues are predominantly found in loop areas. Upon further exploration of the GF-binding spectrum of the two receptors, we found that although many GFs bind both receptors, the high-affinity BMPR2 GFs comprise BMP15, BMP10, and Nodal, whereas those of ACVR2A are activin A, activin B, and GDF11. Lastly, we evaluated GF-binding domain BMPR2 variants found in human PAH patients. We demonstrate that mutations within the GF-binding interface resulted in loss of GF binding, while mutations in loop areas allowed BMPR2 to retain the ability to bind cognate GFs with high affinity. In conclusion, the in vitro activities of BMPR2 variants and the crystal structures reported here indicate biochemically relevant complexes that explain how some GF-binding domain variants can lead to PAH.
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Guo J, Liu B, Thorikay M, Yu M, Li X, Tong Z, Salmon RM, Read RJ, Ten Dijke P, Morrell NW, Li W. Crystal structures of BMPRII extracellular domain in binary and ternary receptor complexes with BMP10. Nat Commun 2022; 13:2395. [PMID: 35504921 PMCID: PMC9064986 DOI: 10.1038/s41467-022-30111-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Accepted: 04/12/2022] [Indexed: 12/23/2022] Open
Abstract
Heterozygous mutations in BMPR2 (bone morphogenetic protein (BMP) receptor type II) cause pulmonary arterial hypertension. BMPRII is a receptor for over 15 BMP ligands, but why BMPR2 mutations cause lung-specific pathology is unknown. To elucidate the molecular basis of BMP:BMPRII interactions, we report crystal structures of binary and ternary BMPRII receptor complexes with BMP10, which contain an ensemble of seven different BMP10:BMPRII 1:1 complexes. BMPRII binds BMP10 at the knuckle epitope, with the A-loop and β4 strand making BMPRII-specific interactions. The BMPRII binding surface on BMP10 is dynamic, and the affinity is weaker in the ternary complex than in the binary complex. Hydrophobic core and A-loop interactions are important in BMPRII-mediated signalling. Our data reveal how BMPRII is a low affinity receptor, implying that forming a signalling complex requires high concentrations of BMPRII, hence mutations will impact on tissues with highest BMPR2 expression such as the lung vasculature.
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Affiliation(s)
- Jingxu Guo
- Department of Medicine, University of Cambridge School of Clinical Medicine, Cambridge, CB2 0QQ, United Kingdom
| | - Bin Liu
- Department of Medicine, University of Cambridge School of Clinical Medicine, Cambridge, CB2 0QQ, United Kingdom
| | - Midory Thorikay
- Department of Cell and Chemical Biology and Oncode Institute, Leiden University Medical Centre, Leiden, The Netherlands
| | - Minmin Yu
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, CB2 0QH, United Kingdom
| | - Xiaoyan Li
- Department of Medicine, University of Cambridge School of Clinical Medicine, Cambridge, CB2 0QQ, United Kingdom
| | - Zhen Tong
- Department of Medicine, University of Cambridge School of Clinical Medicine, Cambridge, CB2 0QQ, United Kingdom
| | - Richard M Salmon
- Department of Medicine, University of Cambridge School of Clinical Medicine, Cambridge, CB2 0QQ, United Kingdom
| | - Randy J Read
- Cambridge Institute for Medical Research, The Keith Peters Building, Cambridge Biomedical Campus, Hills Road, Cambridge, CB2 0XY, United Kingdom
| | - Peter Ten Dijke
- Department of Cell and Chemical Biology and Oncode Institute, Leiden University Medical Centre, Leiden, The Netherlands
| | - Nicholas W Morrell
- Department of Medicine, University of Cambridge School of Clinical Medicine, Cambridge, CB2 0QQ, United Kingdom
| | - Wei Li
- Department of Medicine, University of Cambridge School of Clinical Medicine, Cambridge, CB2 0QQ, United Kingdom.
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4
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Association of distinct type 1 bone morphogenetic protein receptors with different molecular pathways and survival outcomes in neuroblastoma. Neuronal Signal 2020; 4:NS20200006. [PMID: 32714600 PMCID: PMC7366490 DOI: 10.1042/ns20200006] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Revised: 04/14/2020] [Accepted: 04/15/2020] [Indexed: 12/21/2022] Open
Abstract
Neuroblastoma (NB) is a paediatric cancer that arises in the sympathetic nervous system. Patients with stage 4 tumours have poor outcomes and 20% of high-risk cases have MYCN amplification. The bone morphogenetic proteins (BMPs) play roles in sympathetic neuritogenesis, by signalling through bone morphogenetic protein receptor (BMPR)2 and either BMPR1A or BMPR1B. Alterations in BMPR2 expression have been reported in NB; it is unknown if the expression of BMPR1A or BMPR1B is altered. We report lower BMPR2 and BMPR1B, and higher BMPR1A, expression in stage 4 and in MYCN-amplified NB. Kaplan–Meier plots showed that high BMPR2 or BMPR1B expression was linked to better survival, while high BMPR1A was linked to worse survival. Gene ontology enrichment and pathway analyses revealed that BMPR2 and BMPR1B co-expressed genes were enriched in those associated with NB differentiation. BMPR1A co-expressed genes were enriched in those associated with cell proliferation. Moreover, the correlation between BMPR2 and BMPR1A was strengthened, while the correlation between BMPR2 and BMPR1B was lost, in MYCN-amplified NB. This suggested that differentiation should decrease BMPR1A and increase BMPR1B expression. In agreement, nerve growth factor treatment of cultured sympathetic neurons decreased Bmpr1a expression and increased Bmpr1b expression. Overexpression of dominant negative BMPR1B, treatment with a BMPR1B inhibitor and treatment with GDF5, which signals via BMPR1B, showed that BMPR1B signalling is required for optimal neuritogenesis in NB cells, suggesting that loss of BMPR1B may alter neuritogenesis. The present study shows that expression of distinct BMPRs is associated with different survival outcomes in NB.
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Zhang YJ, Qing Q, Zhang YJ, Ning LJ, Cui J, Yao X, Luo JC, Ding W, Qin TW. Enhancement of tenogenic differentiation of rat tendon-derived stem cells by biglycan. J Cell Physiol 2019; 234:15898-15910. [PMID: 30714152 DOI: 10.1002/jcp.28247] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2018] [Revised: 01/12/2019] [Accepted: 01/15/2019] [Indexed: 02/05/2023]
Abstract
Biglycan (BGN) has been identified as one of the critical components of the tendon-derived stem cells (TDSCs) niche and may be related to tendon formation. However, so far, no study has demonstrated whether the soluble BGN could induce the tenogenic differentiation of TDSCs in vitro. The aim of this study was to investigate the effect of BGN on the tenogenic differentiation of TDSCs. The proliferation and tenogenic differentiation of TDSCs exposed to different concentrations of BGN (0, 50, 100, and 500 ng/ml) were determined by the live/dead cell staining assay, CCK-8 assay, quantitative real-time polymerase chain reaction (qRT-PCR), and western blot analysis. The BGN signaling pathway of TDSCs (with and without 50 ng/ml of BGN) was determined by western blot analysis and qRT-PCR analysis. At a concentration of 50 ng/ml, BGN increased the expression of the tenogenic markers THBS-4 and TNMD at both the messenger RNA (mRNA) and protein levels. Meanwhile, 50 ng/ml of BGN inhibited the expression of the chondrogenic and osteogenic markers SOX9, ACN, and RUNX2 at both the mRNA and protein levels. Moreover, BGN (50 ng/ml) affected the expression of the components of the extracellular matrix of TDSCs. Additionally, BGN activated the Smad1/5/8 pathway as indicated by an increase in phosphorylation and demonstrated by inhibition experiments. Upregulation in the gene expression of BMP-associated receptors (BMPRII, ActR-IIa, and BMPR-Ib) and Smad pathway components (Smad4 and 8) was observed. Taken together, BGN regulates tenogenic differentiation of TDSCs via BMP7/Smad1/5/8 pathway and this regulation may provide a basic insight into treating tendon injury.
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Affiliation(s)
- Yan-Jing Zhang
- Laboratory of Stem Cell and Tissue Engineering, State Key Laboratory of Biotherapy/Collaborative Innovation Center for Biotherapy, West China Hospital, Sichuan University, Chengdu, People's Republic of China
| | - Quan Qing
- Division of Tissue Engineering, Regenerative Medicine Research Center, West China Hospital, Sichuan University, Chengdu, People's Republic of China.,Faculty of Basic Medicine, Sichuan College of Traditional Chinese Medicine, Mianyang, People's Republic of China
| | - Ya-Jing Zhang
- Laboratory of Stem Cell and Tissue Engineering, State Key Laboratory of Biotherapy/Collaborative Innovation Center for Biotherapy, West China Hospital, Sichuan University, Chengdu, People's Republic of China
| | - Liang-Ju Ning
- Laboratory of Stem Cell and Tissue Engineering, State Key Laboratory of Biotherapy/Collaborative Innovation Center for Biotherapy, West China Hospital, Sichuan University, Chengdu, People's Republic of China
| | - Jing Cui
- Laboratory of Stem Cell and Tissue Engineering, State Key Laboratory of Biotherapy/Collaborative Innovation Center for Biotherapy, West China Hospital, Sichuan University, Chengdu, People's Republic of China
| | - Xuan Yao
- Laboratory of Stem Cell and Tissue Engineering, State Key Laboratory of Biotherapy/Collaborative Innovation Center for Biotherapy, West China Hospital, Sichuan University, Chengdu, People's Republic of China
| | - Jing-Cong Luo
- Laboratory of Stem Cell and Tissue Engineering, State Key Laboratory of Biotherapy/Collaborative Innovation Center for Biotherapy, West China Hospital, Sichuan University, Chengdu, People's Republic of China
| | - Wei Ding
- Laboratory of Stem Cell and Tissue Engineering, State Key Laboratory of Biotherapy/Collaborative Innovation Center for Biotherapy, West China Hospital, Sichuan University, Chengdu, People's Republic of China
| | - Ting-Wu Qin
- Laboratory of Stem Cell and Tissue Engineering, State Key Laboratory of Biotherapy/Collaborative Innovation Center for Biotherapy, West China Hospital, Sichuan University, Chengdu, People's Republic of China
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Ongaro L, Schang G, Ho CC, Zhou X, Bernard DJ. TGF-β Superfamily Regulation of Follicle-Stimulating Hormone Synthesis by Gonadotrope Cells: Is There a Role for Bone Morphogenetic Proteins? Endocrinology 2019; 160:675-683. [PMID: 30715256 PMCID: PMC6388655 DOI: 10.1210/en.2018-01038] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/09/2018] [Accepted: 01/28/2019] [Indexed: 02/08/2023]
Abstract
Bone morphogenetic proteins (BMPs) are pleiotropic ligands in the TGF-β superfamily. In the early to mid-2000s, several BMPs, including BMP2, were shown to regulate FSH synthesis alone and in synergy with activins in immortalized gonadotrope-like cell lines and primary pituitary cultures. Activins are also TGF-β family members, which were identified and named based on their abilities to stimulate FSH production selectively. Mechanistic analyses suggested that BMP2 promoted expression of the FSHβ subunit gene (Fshb) via at least two nonmutually exclusive mechanisms. First, BMP2 stimulated the production of the inhibitor of DNA-binding proteins 1, 2, and 3 (Id1, Id2, and Id3), which potentiated the stimulatory actions of homolog of Drosophila mothers against decapentaplegic 3 (SMAD3) on the Fshb promoter. SMAD3 is an intracellular signaling protein that canonically mediates the actions of activins and is an essential regulator of Fshb production in vitro and in vivo. Second, BMP2 was shown to activate SMAD3-dependent signaling via its canonical type IA receptor, BMPR1A (also known as ALK3). This was a surprising result, as ALK3 conventionally activates distinct SMAD proteins. Although these initial results were compelling, they were challenged by contemporaneous and subsequent observations. For example, inhibitors of BMP signaling did not specifically impair FSH production in cultured pituitary cells. Of perhaps greater significance, mice lacking ALK3 in gonadotrope cells produced FSH normally. Therefore, the physiological role of BMPs in FSH synthesis in vivo is presently uncertain.
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Affiliation(s)
- Luisina Ongaro
- Department of Pharmacology and Therapeutics, Centre for Research in Reproduction and Development, McGill University, Montreal, Quebec, Canada
| | - Gauthier Schang
- Department of Pharmacology and Therapeutics, Centre for Research in Reproduction and Development, McGill University, Montreal, Quebec, Canada
| | - Catherine C Ho
- Department of Pharmacology and Therapeutics, Centre for Research in Reproduction and Development, McGill University, Montreal, Quebec, Canada
| | - Xiang Zhou
- Department of Pharmacology and Therapeutics, Centre for Research in Reproduction and Development, McGill University, Montreal, Quebec, Canada
| | - Daniel J Bernard
- Department of Pharmacology and Therapeutics, Centre for Research in Reproduction and Development, McGill University, Montreal, Quebec, Canada
- Correspondence: Daniel J. Bernard, PhD, Department of Pharmacology and Therapeutics, McGill University, 3655 Promenade Sir William Osler, Room 1315, Montréal, Québec H3G 1Y6, Canada. E-mail:
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7
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Rauner M, Baschant U, Roetto A, Pellegrino RM, Rother S, Salbach-Hirsch J, Weidner H, Hintze V, Campbell G, Petzold A, Lemaitre R, Henry I, Bellido T, Theurl I, Altamura S, Colucci S, Muckenthaler MU, Schett G, Komla Ebri D, Bassett JHD, Williams GR, Platzbecker U, Hofbauer LC. Transferrin receptor 2 controls bone mass and pathological bone formation via BMP and Wnt signaling. Nat Metab 2019; 1:111-124. [PMID: 30886999 PMCID: PMC6420074 DOI: 10.1038/s42255-018-0005-8] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Transferrin receptor 2 (Tfr2) is mainly expressed in the liver and controls iron homeostasis. Here, we identify Tfr2 as a regulator of bone homeostasis that inhibits bone formation. Mice lacking Tfr2 display increased bone mass and mineralization independent of iron homeostasis and hepatic Tfr2. Bone marrow transplantation experiments and studies of cell-specific Tfr2 knockout mice demonstrate that Tfr2 impairs BMP-p38MAPK signaling and decreases expression of the Wnt inhibitor sclerostin specifically in osteoblasts. Reactivation of MAPK or overexpression of sclerostin rescues skeletal abnormalities in Tfr2 knockout mice. We further show that the extracellular domain of Tfr2 binds BMPs and inhibits BMP-2-induced heterotopic ossification by acting as a decoy receptor. These data indicate that Tfr2 limits bone formation by modulating BMP signaling, possibly through direct interaction with BMP either as a receptor or as a co-receptor in a complex with other BMP receptors. Finally, the Tfr2 extracellular domain may be effective in the treatment of conditions associated with pathological bone formation.
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Affiliation(s)
- Martina Rauner
- Department of Medicine III, Technische Universität Dresden, Dresden, Germany
- Center for Healthy Aging, Technische Universität Dresden, Dresden, Germany
| | - Ulrike Baschant
- Department of Medicine III, Technische Universität Dresden, Dresden, Germany
- Center for Healthy Aging, Technische Universität Dresden, Dresden, Germany
| | - Antonella Roetto
- Department of Clinical and Biological Science, University of Torino, Torino, Italy
| | | | - Sandra Rother
- Institute of Materials Science, Max Bergmann Center of Biomaterials, Technische Universität Dresden, Dresden, Germany
| | - Juliane Salbach-Hirsch
- Department of Medicine III, Technische Universität Dresden, Dresden, Germany
- Center for Healthy Aging, Technische Universität Dresden, Dresden, Germany
| | - Heike Weidner
- Department of Medicine III, Technische Universität Dresden, Dresden, Germany
- Center for Healthy Aging, Technische Universität Dresden, Dresden, Germany
| | - Vera Hintze
- Institute of Materials Science, Max Bergmann Center of Biomaterials, Technische Universität Dresden, Dresden, Germany
| | - Graeme Campbell
- Institute of Biomechanics, Hamburg University of Technology, Hamburg, Germany
| | - Andreas Petzold
- Deep Sequencing, Biotechnology Center, Technische Universität Dresden, Dresden, Germany
| | - Regis Lemaitre
- Max Planck Institute for Cell Biology and Genetics, Protein Unit, Dresden, Germany
| | - Ian Henry
- Max Planck Institute for Cell Biology and Genetics, Scientific Computing Facility, Dresden, Germany
| | - Teresita Bellido
- Department of Anatomy and Cell Biology and Department of Medicine, Division of Endocrinology, School of Medicine, Indiana University, Indianapolis, IN, USA
| | - Igor Theurl
- Department of Internal Medicine VI, Medical University of Innsbruck, Innsbruck, Austria
| | - Sandro Altamura
- Department of Pediatric Hematology, Oncology and Immunology, University of Heidelberg, Heidelberg, Germany
| | - Silvia Colucci
- Department of Pediatric Hematology, Oncology and Immunology, University of Heidelberg, Heidelberg, Germany
| | - Martina U. Muckenthaler
- Department of Pediatric Hematology, Oncology and Immunology, University of Heidelberg, Heidelberg, Germany
| | - Georg Schett
- Department of Internal Medicine 3, Friedrich-Alexander-University Erlangen-Nuremberg (FAU) and University Hospital Erlangen, Erlangen, Germany
| | - Davide Komla Ebri
- Molecular Endocrinology Laboratory, Department of Medicine, Imperial College London, London W12 0NN, United Kingdom
| | - J. H. Duncan Bassett
- Molecular Endocrinology Laboratory, Department of Medicine, Imperial College London, London W12 0NN, United Kingdom
| | - Graham R. Williams
- Molecular Endocrinology Laboratory, Department of Medicine, Imperial College London, London W12 0NN, United Kingdom
| | - Uwe Platzbecker
- Center for Healthy Aging, Technische Universität Dresden, Dresden, Germany
- Department of Medicine II, University Clinic Leipzig, Germany
- German Cancer Consortium (DKTK) Partner Site Dresden, Dresden, Germany
| | - Lorenz C. Hofbauer
- Department of Medicine III, Technische Universität Dresden, Dresden, Germany
- Center for Healthy Aging, Technische Universität Dresden, Dresden, Germany
- German Cancer Consortium (DKTK) Partner Site Dresden, Dresden, Germany
- Center for Regenerative Therapies Dresden, Technische Universität Dresden, Dresden, Germany
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8
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Targeting bone morphogenetic protein signalling in midbrain dopaminergic neurons as a therapeutic approach in Parkinson's disease. Neuronal Signal 2017; 1:NS20170027. [PMID: 32714578 PMCID: PMC7373244 DOI: 10.1042/ns20170027] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2017] [Revised: 02/20/2017] [Accepted: 02/23/2017] [Indexed: 11/17/2022] Open
Abstract
Parkinson's disease (PD) is the second most common neurodegenerative disease, characterized by the degeneration of midbrain dopaminergic (mDA) neurons and their axons, and aggregation of α-synuclein, which leads to motor and late-stage cognitive impairments. As the motor symptoms of PD are caused by the degeneration of a specific population of mDA neurons, PD lends itself to neurotrophic factor therapy. The goal of this therapy is to apply a neurotrophic factor that can slow down, halt or even reverse the progressive degeneration of mDA neurons. While the best known neurotrophic factors are members of the glial cell line-derived neurotrophic factor (GDNF) family, their lack of clinical efficacy to date means that it is important to continue to study other neurotrophic factors. Bone morphogenetic proteins (BMPs) are naturally secreted proteins that play critical roles during nervous system development and in the adult brain. In this review, we provide an overview of the BMP ligands, BMP receptors (BMPRs) and their intracellular signalling effectors, the Smad proteins. We review the available evidence that BMP-Smad signalling pathways play an endogenous role in mDA neuronal survival in vivo, before outlining how exogenous application of BMPs exerts potent effects on mDA neuron survival and axon growth in vitro and in vivo. We discuss the molecular mechanisms that mediate these effects, before highlighting the potential of targeting the downstream effectors of BMP-Smad signalling as a novel neuroprotective approach to slow or stop the degeneration of mDA neurons in PD.
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Abstract
We review the evolution and structure of members of the transforming growth factor β (TGF-β) family, antagonistic or agonistic modulators, and receptors that regulate TGF-β signaling in extracellular environments. The growth factor (GF) domain common to all family members and many of their antagonists evolved from a common cystine knot growth factor (CKGF) domain. The CKGF superfamily comprises six distinct families in primitive metazoans, including the TGF-β and Dan families. Compared with Wnt/Frizzled and Notch/Delta families that also specify body axes, cell fate, tissues, and other families that contain CKGF domains that evolved in parallel, the TGF-β family was the most fruitful in evolution. Complexes between the prodomains and GFs of the TGF-β family suggest a new paradigm for regulating GF release by conversion from closed- to open-arm procomplex conformations. Ternary complexes of the final step in extracellular signaling show how TGF-β GF dimers bind type I and type II receptors on the cell surface, and enable understanding of much of the specificity and promiscuity in extracellular signaling. However, structures suggest that when GFs bind repulsive guidance molecule (RGM) family coreceptors, type I receptors do not bind until reaching an intracellular, membrane-enveloped compartment, blurring the line between extra- and intracellular signaling. Modulator protein structures show how structurally diverse antagonists including follistatins, noggin, and members of the chordin family bind GFs to regulate signaling; complexes with the Dan family remain elusive. Much work is needed to understand how these molecular components assemble to form signaling hubs in extracellular environments in vivo.
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Affiliation(s)
- Andrew P Hinck
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15260
| | - Thomas D Mueller
- Department of Plant Physiology and Biophysics, Julius-von-Sachs Institute of the University Wuerzburg, D-97082 Wuerzburg, Germany
| | - Timothy A Springer
- Program in Cellular and Molecular Medicine and Division of Hematology, Department of Medicine, Boston Children's Hospital, Boston, Massachusetts 02115
- Department of Biological Chemistry and Pharmacology, Harvard Medical School, Boston, Massachusetts 02115
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10
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An investigation of BMP-7 mediated alterations to BMP signalling components in human tenocyte-like cells. Sci Rep 2016; 6:29703. [PMID: 27406972 PMCID: PMC4942578 DOI: 10.1038/srep29703] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2016] [Accepted: 06/21/2016] [Indexed: 12/12/2022] Open
Abstract
The incidence of tendon re-tears post-surgery is an ever present complication. It is suggested that the application of biological factors, such as bone morphogenetic protein 7 (BMP-7), can reduce complication rates by promoting tenogenic characteristics in in vitro studies. However, there remains a dearth of information in regards to the mechanisms of BMP-7 signalling in tenocytes. Using primary human tenocyte-like cells (hTLCs) from the supraspinatus tendon the BMP-7 signalling pathway was investigated: induction of the BMP associated Smad pathway and non-Smad pathways (AKT, p38, ERK1/2 and JNK); alterations in gene expression of BMP-7 associated receptors, Smad pathway components, Smad target gene (ID1) and tenogenic marker scleraxis. BMP-7 increases the expression of specific BMP associated receptors, BMPR-Ib and BMPR-II, and Smad8. Additionally, BMP-7 activates significantly Smad1/5/8 and slightly p38 pathways as indicated by an increase in phosphorylation and proven by inhibition experiments, where p-ERK1/2 and p-JNK pathways remain mainly unresponsive. Furthermore, BMP-7 increases the expression of the Smad target gene ID1, and the tendon specific transcription factor scleraxis. The study shows that tenocyte-like cells undergo primarily Smad8 and p38 signalling after BMP-7 stimulation. The up-regulation of tendon related marker genes and matrix proteins such as Smad8/9, scleraxis and collagen I might lead to positive effects of BMP-7 treatment for rotator cuff repair, without significant induction of osteogenic and chondrogenic markers.
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11
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Huang T, Hinck AP. Production, Isolation, and Structural Analysis of Ligands and Receptors of the TGF-β Superfamily. Methods Mol Biol 2016; 1344:63-92. [PMID: 26520118 PMCID: PMC4846357 DOI: 10.1007/978-1-4939-2966-5_4] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/25/2023]
Abstract
The ability to understand the molecular mechanisms by which secreted signaling proteins of the TGF-β superfamily assemble their cell surface receptors into complexes to initiate downstream signaling is dependent upon the ability to determine atomic-resolution structures of the signaling proteins, the ectodomains of the receptors, and the complexes that they form. The structures determined to date have revealed major differences in the overall architecture of the signaling complexes formed by the TGF-βs and BMPs, which has provided insights as to how they have evolved to fulfill their distinct functions. Such studies, have however, only been applied to a few members of the TGF-β superfamily, which is largely due to the difficulty of obtaining milligram-scale quantities of highly homogenous preparations of the disulfide-rich signaling proteins and receptor ectodomains of the superfamily. Here we describe methods used to produce signaling proteins and receptor ectodomains of the TGF-β superfamily using bacterial and mammalian expression systems and procedures to purify them to homogeneity.
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Affiliation(s)
- Tao Huang
- Protein Chemistry, Novo Nordisk Research Center China, 20 Life Science Park Rd, Bldg 2, Beijing, 102206, China
| | - Andrew P Hinck
- Protein Chemistry, Novo Nordisk Research Center China, 20 Life Science Park Rd, Bldg 2, Beijing, 102206, China.
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12
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Evangelista W, Yeh LCC, Gmyrek A, Lee JC, Lee JC. Long-Range Communication Network in the Type 1B Bone Morphogenetic Protein Receptor. Biochemistry 2015; 54:7079-88. [PMID: 26562759 DOI: 10.1021/acs.biochem.5b00955] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Protein-protein interactions are recognized as a fundamental phenomenon that is intimately associated with biological functions and thus are ideal targets for developing modulators for regulating biological functions. A challenge is to identify a site that is situated away from but functionally connected to the protein-protein interface. We employed bone morphogenetic proteins (BMPs) and their receptors as a model system to develop a strategy for identifying such a network of communication. Accordingly, using computational analyses with the COREX/BEST algorithm, we uncovered an overall pattern connecting various regions of BMPR-1B ectodomain, including the four conserved residues in the protein-protein interface. In preparation for testing the long-range effects of mutations of distal residues for future studies, we examined the extent of measurable perturbation of the four conserved residues by determination of the conformation and relative affinities of these BMPR-1B mutants for ligands BMP-2, -6, and -7 and GDF-5. Results suggest no significant structural changes in the receptor but do suggest that the four residues play different roles in defining ligand affinity and both intra- and intermolecular interactions play a role in defining ligand affinity. Thus, these results established two primary but necessary goals: (1) the baseline knowledge of perturbation of conserved interfacial residues for future reference and (2) the ability of the computational approach to identify the distal residues connecting to the interfacial residues. The data presented here provide the foundation for future experiments to identify the effects of distal residues that affect the specificity and affinity of BMP recognition. Protein-protein interactions are integral reactions in essentially all biological activities such as gene regulation and age-related development. Often, diseases are consequences of the alteration of these intermacromolecular interactions, which are thus recognized as a legitimate target for developing modulators for regulating biological functions. One approach is to design ligands that bind to the protein-protein interface. Another is to identify an allosteric site, an advantage of which is bypassing the potential challenge in competing for high-affinity interfacial interactions or a specific interface in a superassembly of multiple macromolecules. However, a challenge of this approach is identifying a site that is situated away from but functionally connected to the protein-protein interface.
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Affiliation(s)
- Wilfredo Evangelista
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch , Galveston, Texas 77555-1055, United States
| | - Lee-Chuan C Yeh
- Department of Biochemistry, University of Texas Health Science Center at San Antonio , San Antonio, Texas 78229, United States
| | - Aleksandra Gmyrek
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch , Galveston, Texas 77555-1055, United States
| | - J Ching Lee
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch , Galveston, Texas 77555-1055, United States
| | - John C Lee
- Department of Biochemistry, University of Texas Health Science Center at San Antonio , San Antonio, Texas 78229, United States
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Lowery JW, Amich JM, Andonian A, Rosen V. N-linked glycosylation of the bone morphogenetic protein receptor type 2 (BMPR2) enhances ligand binding. Cell Mol Life Sci 2013; 71:3165-72. [PMID: 24337809 DOI: 10.1007/s00018-013-1541-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2013] [Revised: 11/28/2013] [Accepted: 12/02/2013] [Indexed: 02/07/2023]
Abstract
The bone morphogenetic protein (BMP) signaling pathway is essential for normal development and tissue homeostasis. BMP signal transduction occurs when ligands interact with a complex of type 1 and type 2 receptors to activate downstream transcription factors. It is well established that a single BMP receptor may bind multiple BMP ligands with varying affinity, and this has been largely attributed to conformation at the amino acid level. However, all three type 2 BMP receptors (BMPR2, ACVR2A/B) contain consensus N-glycosylation sites in their extracellular domains (ECDs), which could play a role in modulating interaction with ligand. Here, we show a differential pattern of N-glycosylation between BMPR2 and ACVR2A/B. Site-directed mutagenesis reveals that BMPR2 is uniquely glycosylated near its ligand binding domain and at a position that is mutated in patients with heritable pulmonary arterial hypertension. We further demonstrate using a cell-free pulldown assay that N-glycosylation of the BMPR2-ECD enhances its ability to bind BMP2 ligand but has no impact on binding by the closely-related ACVR2B. Our results illuminate a novel aspect of BMP signaling pathway mechanics and demonstrate a functional difference resulting from post-translational modification of type 2 BMP receptors. Additionally, since BMPR2 is required for several aspects of normal development and defects in its function are strongly implicated in human disease, our findings are likely to be relevant in several biological contexts in normal and abnormal human physiology.
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Affiliation(s)
- Jonathan W Lowery
- Department of Developmental Biology, Harvard School of Dental Medicine, Boston, MA, USA,
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Frump AL, Lowery JW, Hamid R, Austin ED, de Caestecker M. Abnormal trafficking of endogenously expressed BMPR2 mutant allelic products in patients with heritable pulmonary arterial hypertension. PLoS One 2013; 8:e80319. [PMID: 24224048 PMCID: PMC3818254 DOI: 10.1371/journal.pone.0080319] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2013] [Accepted: 10/07/2013] [Indexed: 12/28/2022] Open
Abstract
More than 200 heterozygous mutations in the type 2 BMP receptor gene, BMPR2, have been identified in patients with Heritable Pulmonary Arterial Hypertension (HPAH). More severe clinical outcomes occur in patients with BMPR2 mutations by-passing nonsense-mediated mRNA decay (NMD negative mutations). These comprise 40% of HPAH mutations and are predicted to express BMPR2 mutant products. However expression of endogenous NMD negative BMPR2 mutant products and their effect on protein trafficking and signaling function have never been described. Here, we characterize the expression and trafficking of an HPAH-associated NMD negative BMPR2 mutation that results in an in-frame deletion of BMPR2 EXON2 (BMPR2ΔEx2) in HPAH patient-derived lymphocytes and in pulmonary endothelial cells (PECs) from mice carrying the same in-frame deletion of Exon 2 (Bmpr2 (ΔEx2/+) mice). The endogenous BMPR2ΔEx2 mutant product does not reach the cell surface and is retained in the endoplasmic reticulum. Moreover, chemical chaperones 4-PBA and TUDCA partially restore cell surface expression of Bmpr2ΔEx2 in PECs, suggesting that the mutant product is mis-folded. We also show that PECs from Bmpr2 (ΔEx2/+) mice have defects in the BMP-induced Smad1/5/8 and Id1 signaling axis, and that addition of chemical chaperones restores expression of the Smad1/5/8 target Id1. These data indicate that the endogenous NMD negative BMPRΔEx2 mutant product is expressed but has a folding defect resulting in ER retention. Partial correction of this folding defect and restoration of defective BMP signaling using chemical chaperones suggests that protein-folding agents could be used therapeutically in patients with these NMD negative BMPR2 mutations.
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Affiliation(s)
- Andrea L. Frump
- Department of Cell and Developmental Biology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Jonathan W. Lowery
- Department of Developmental Biology, Harvard University School of Dental Medicine, Boston, Massachusetts, United States of America
| | - Rizwan Hamid
- Department of Pediatrics, Division of Molecular Genetics and Genomic Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Eric D. Austin
- Department of Pediatrics, Division of Pediatric Pulmonary Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Mark de Caestecker
- Department of Cell and Developmental Biology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
- *E-mail:
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Yeh LCC, Falcon WE, Garces A, Lee JC, Lee JC. A host-guest relationship in bone morphogenetic protein receptor-II defines specificity in ligand-receptor recognition. Biochemistry 2012; 51:6968-80. [PMID: 22894880 DOI: 10.1021/bi3003023] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
One of the most intriguing questions confronting the bone morphogenetic protein family is the mechanism of ligand recognition, because there are more ligands than receptors. Crystal structures of two type II receptors, ActR-II and BMPR-II, are essentially identical, and a loop structure (A-loop) has been suggested to play a role in determining ligand specificity. A solution biophysical study showed mutations of several A-loop residues in these two receptors exert different ligand binding effects. Thus, the issues of mechanism of ligand recognition and specificity remain unresolved. We examined effects of mutations of residues Y40, G47, and S107 in BMPR-II. These residues are not identified as being in contact with the ligand in the BMP-7-BMPR-II complex but are found mutated in genetic diseases. They are likely to be useful in identifying their roles in differentiating the various BMP ligands. Spectroscopic probing revealed little mutation-induced structural change in BMPR-II. Ligand binding studies revealed that Y40 plays a significant role in differentiating three distinct ligands; G47 and S107 affect ligand binding to a lesser extent. The role of the A-loop in ActR-II or BMPR-II is dependent on the host sequence of the receptor extracellular domain (ECD) in which it is embedded, suggesting a host-guest relationship between the A-loop and the rest of the ECD. Computational analysis demonstrated a long-range connectivity between Y40, G47, and S107 and other locations in BMPR-II. An integration of these results on functional energetics and protein structures clearly demonstrates, for the first time, an intradomain communication network within BMPR-II.
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Affiliation(s)
- Lee-Chuan C Yeh
- Department of Biochemistry, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
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Perron JC, Dodd J. Structural distinctions in BMPs underlie divergent signaling in spinal neurons. Neural Dev 2012; 7:16. [PMID: 22559862 PMCID: PMC3403000 DOI: 10.1186/1749-8104-7-16] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2012] [Accepted: 04/04/2012] [Indexed: 12/23/2022] Open
Abstract
BACKGROUND In dorsal spinal neurons and monocytes, bone morphogenetic protein (BMP)7 activates distinct transduction pathways, one leading to inductive specification and the other to axon orientation and chemotaxis. BMP7-evoked induction, also stimulated by the closely related BMP6, acts through a Smad cascade, leading to nuclear signaling, and is not BMPR subunit selective. Orientation is evoked by BMP7, but not by BMP6, through PI3K-dependent cytoskeletal activation mediated by the type II BMPRs, ActRIIA and BMPRII and is independent of the Smad cascade. The responses can be stimulated concurrently and suggest that BMP7, but not BMP6, can selectively activate BMPR subunits that engage the divergent paths. Although structural and biochemical analyses of selected BMP/BMPR interfaces have identified key regions of interaction, how these translate into function by related BMPs is poorly understood. To determine the mechanisms underlying the distinct activities of BMP7 and the disparate properties of BMP7 and BMP6 in spinal cord development, we have performed a family-wide structure/function analysis of BMPs and used the information to predict and test sites within BMPs that may control agonist properties, in particular the ability of a BMP to orient axons, through interactions with BMPRs. RESULTS We demonstrate that whereas all BMPs can induce dorsal neurons, there is selectivity in the ability also to orient axons or evoke growth cone collapse. The degree to which a BMP orients is not predictable by overall protein similarity with other BMPs but comparison of sequences of potent and weakly orienting BMPs with that of the non-orienting BMP6 revealed three candidate positions within the BMPs at which the amino acid residues may confer or obstruct orienting ability. Residue swapping analysis has identified one residue, Gln48 in BMP6, that blocks axon orienting ability. Replacing Gln48 with any of the amino acids present at the equivalent residue position in the orienting subset of BMPs confers orienting activity on BMP6. Conversely, swapping Gln48 into BMP7 reduces orienting ability. The inductive capacity of the BMPs was unchanged by these residue swaps. CONCLUSIONS The results suggest that the presence of the Gln48 residue in BMP6 is structurally inhibitory for BMP/BMPR interactions that result in the activation of intracellular signaling, leading to axon orientation. Moreover, since residue 48 in BMP7 and the corresponding residue in BMP2 are important for type II BMPR binding, our results provide a basis for a mechanistic understanding of the diverse activities of BMPs in spinal cord development.
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Affiliation(s)
- Jeanette C Perron
- Department of Physiology and Cellular Biophysics, Columbia University, 630 West 168th Street, BB1103, New York, NY 10032, USA
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Promiscuity and specificity in BMP receptor activation. FEBS Lett 2012; 586:1846-59. [PMID: 22710174 DOI: 10.1016/j.febslet.2012.02.043] [Citation(s) in RCA: 219] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2012] [Revised: 02/28/2012] [Accepted: 02/29/2012] [Indexed: 02/03/2023]
Abstract
Bone Morphogenetic Proteins (BMPs), together with Transforming Growth Factor (TGF)-β and Activins/Inhibins constitute the TGF-β superfamily of ligands. This superfamily is formed by more than 30 structurally related secreted proteins. Since TGF-β members act as morphogens, either a strict relation between a particular ligand to a distinct cellular receptor and/or temporospatial expression patterns of ligands and receptors is expected. Instead, only a limited number of receptors exist implicating promiscuous interactions of ligands and receptors. Furthermore, in complex tissues a multitude of different ligands can be found, which signal via overlapping subsets of receptors. This raises the intriguing question how concerted interactions of different ligands and receptors generate highly specific cellular signals, which are required during development and tissue homeostasis.
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Zouani OF, Chollet C, Guillotin B, Durrieu MC. Differentiation of pre-osteoblast cells on poly(ethylene terephthalate) grafted with RGD and/or BMPs mimetic peptides. Biomaterials 2010; 31:8245-53. [PMID: 20667411 DOI: 10.1016/j.biomaterials.2010.07.042] [Citation(s) in RCA: 88] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2010] [Accepted: 07/07/2010] [Indexed: 01/18/2023]
Abstract
The bone morphogenetic proteins (BMPs) are cytokines of the transforming growth factor beta family. Some BMPs such as BMP-2, BMP-7 and BMP-9 play a major role in the bone and cartilage formation. The BMP peptides corresponding to residues 73-92, 89-117, and 68-87 of BMP-2, BMP-7 and BMP-9 respectively as well as adhesion peptides (GRGDSPC) were grafted onto polyethylene terephthatalate (PET) surfaces. We evaluated the state of differentiation of pre-osteoblastic cells. The behavior of these cells on various functionalized surfaces highlighted the activity of the mimetic peptides immobilized on surfaces. The induced cells (observed in the case of surfaces grafted with BMP-2, 7 or 9 mimetic peptides and GRGDSPC peptides) were characterized on several levels. First of all, we focused on the evaluation of the osteoblastic markers such as the transcriptional factor Runx2, which is a critical regulator of osteoblastic differentiation. Secondly, the results obtained showed that these induced cells take a different morphology compared to the cells in a state of proliferation or in a state of extracellular matrix production. Induced cells were characterized by an increased thickness compared to non-induced cells. Thus, our studies prove a direct correlation between cell morphology and state of induction. Thereafter, we focused on characterizing the extracellular matrix formed by the cells on various surfaces. The extracellular matrix thickness was more significant in the case of surfaces grafted with mimetic peptides of the BMP-2, 7 or 9 and GRGDSPC peptides which once again proves their activity when immobilized on material surface. These results demonstrate that GRGDSPC and BMPs peptides, grafted to PET surface, act to enhance osteogenic differentiation and mineralization of pre-osteoblastic cells. These findings are potentially useful in developing engineered biomaterials for bone regeneration.
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Affiliation(s)
- Omar F Zouani
- INSERM, U577, Biomatériaux et Réparation Tissulaire, Univ Victor Segalen Bordeaux 2, Bordeaux, 146 rue Léo Saignat, 33076 Bordeaux Cedex, France.
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Rich RL, Myszka DG. Grading the commercial optical biosensor literature-Class of 2008: 'The Mighty Binders'. J Mol Recognit 2010; 23:1-64. [PMID: 20017116 DOI: 10.1002/jmr.1004] [Citation(s) in RCA: 109] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Optical biosensor technology continues to be the method of choice for label-free, real-time interaction analysis. But when it comes to improving the quality of the biosensor literature, education should be fundamental. Of the 1413 articles published in 2008, less than 30% would pass the requirements for high-school chemistry. To teach by example, we spotlight 10 papers that illustrate how to implement the technology properly. Then we grade every paper published in 2008 on a scale from A to F and outline what features make a biosensor article fabulous, middling or abysmal. To help improve the quality of published data, we focus on a few experimental, analysis and presentation mistakes that are alarmingly common. With the literature as a guide, we want to ensure that no user is left behind.
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Affiliation(s)
- Rebecca L Rich
- Center for Biomolecular Interaction Analysis, University of Utah, Salt Lake City, UT 84132, USA
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Deshmukh K, Anamika K, Srinivasan N. Evolution of domain combinations in protein kinases and its implications for functional diversity. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2009; 102:1-15. [PMID: 20026163 DOI: 10.1016/j.pbiomolbio.2009.12.009] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2009] [Accepted: 12/10/2009] [Indexed: 01/01/2023]
Abstract
Protein kinases phosphorylating Ser/Thr/Tyr residues in several cellular proteins exert tight control over their biological functions. They constitute the largest protein family in most eukaryotic species. Protein kinases classified based on sequence similarity in their catalytic domains, cluster into subfamilies, which share gross functional properties. Many protein kinases are associated or tethered covalently to domains that serve as adapter or regulatory modules, aiding substrate recruitment, specificity, and also serve as scaffolds. Hence the modular organisation of the protein kinases serves as guidelines to their functional and molecular properties. Analysis of genomic repertoires of protein kinases in eukaryotes have revealed wide spectrum of domain organisation across various subfamilies of kinases. Occurrence of organism-specific novel domain combinations suggests functional diversity achieved by protein kinases in order to regulate variety of biological processes. In addition, domain architecture of protein kinases revealed existence of hybrid protein kinase subfamilies and their emerging roles in the signaling of eukaryotic organisms. In this review we discuss the repertoire of non-kinase domains tethered to multi-domain kinases in the metazoans. Similarities and differences in the domain architectures of protein kinases in these organisms indicate conserved and unique features that are critical to functional specialization.
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Affiliation(s)
- Krupa Deshmukh
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560 012, India
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Heinecke K, Seher A, Schmitz W, Mueller TD, Sebald W, Nickel J. Receptor oligomerization and beyond: a case study in bone morphogenetic proteins. BMC Biol 2009; 7:59. [PMID: 19735544 PMCID: PMC2749821 DOI: 10.1186/1741-7007-7-59] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2009] [Accepted: 09/07/2009] [Indexed: 11/13/2022] Open
Abstract
Background Transforming growth factor (TGF)β superfamily members transduce signals by oligomerizing two classes of serine/threonine kinase receptors, termed type I and type II. In contrast to the large number of ligands only seven type I and five type II receptors have been identified in mammals, implicating a prominent promiscuity in ligand-receptor interaction. Since a given ligand can usually interact with more than one receptor of either subtype, differences in binding affinities and specificities are likely important for the generation of distinct ligand-receptor complexes with different signaling properties. Results In vitro interaction analyses showed two different prototypes of binding kinetics, 'slow on/slow off' and 'fast on/fast off'. Surprisingly, the binding specificity of ligands to the receptors of one subtype is only moderate. As suggested from the dimeric nature of the ligands, binding to immobilized receptors shows avidity due to cooperative binding caused by bivalent ligand-receptor interactions. To compare these in vitro observations to the situation in vivo, binding studies on whole cells employing homodimeric as well as heterodimeric bone morphogenetic protein 2 (BMP2) mutants were performed. Interestingly, low and high affinity binding sites were identified, as defined by the presence of either one or two BMP receptor (BMPR)-IA receptor chains, respectively. Both sites contribute to different cellular responses in that the high affinity sites allow a rapid transient response at low ligand concentrations whereas the low affinity sites facilitate sustained signaling but higher ligand concentrations are required. Conclusion Binding of a ligand to a single high affinity receptor chain functioning as anchoring molecule and providing sufficient complex stability allows the subsequent formation of signaling competent complexes. Another receptor of the same subtype, and up to two receptors of the other subtype, can then be recruited. Thus, the resulting receptor arrangement can principally consist of four different receptors, which is consistent with our interaction analysis showing low ligand-receptor specificity within one subtype class. For BMP2, further complexity is added by the fact that heterooligomeric signaling complexes containing only one type I receptor chain can also be found. This indicates that despite prominent ligand receptor promiscuity a manifold of diverse signals might be generated in this receptor limited system.
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Affiliation(s)
- Kai Heinecke
- Physiologische Chemie II, Biozentrum, Universität Würzburg, Würzburg, Germany.
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