51
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Wong MY, DiChiara AS, Suen PH, Chen K, Doan ND, Shoulders MD. Adapting Secretory Proteostasis and Function Through the Unfolded Protein Response. Curr Top Microbiol Immunol 2018; 414:1-25. [PMID: 28929194 DOI: 10.1007/82_2017_56] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Cells address challenges to protein folding in the secretory pathway by engaging endoplasmic reticulum (ER)-localized protective mechanisms that are collectively termed the unfolded protein response (UPR). By the action of the transmembrane signal transducers IRE1, PERK, and ATF6, the UPR induces networks of genes whose products alleviate the burden of protein misfolding. The UPR also plays instructive roles in cell differentiation and development, aids in the response to pathogens, and coordinates the output of professional secretory cells. These functions add to and move beyond the UPR's classical role in addressing proteotoxic stress. Thus, the UPR is not just a reaction to protein misfolding, but also a fundamental driving force in physiology and pathology. Recent efforts have yielded a suite of chemical genetic methods and small molecule modulators that now provide researchers with both stress-dependent and -independent control of UPR activity. Such tools provide new opportunities to perturb the UPR and thereby study mechanisms for maintaining proteostasis in the secretory pathway. Numerous observations now hint at the therapeutic potential of UPR modulation for diseases related to the misfolding and aggregation of ER client proteins. Growing evidence also indicates the promise of targeting ER proteostasis nodes downstream of the UPR. Here, we review selected advances in these areas, providing a resource to inform ongoing studies of secretory proteostasis and function as they relate to the UPR.
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Affiliation(s)
- Madeline Y Wong
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Ave, Cambridge, MA, 02139-4307, USA
| | - Andrew S DiChiara
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Ave, Cambridge, MA, 02139-4307, USA
| | - Patreece H Suen
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Ave, Cambridge, MA, 02139-4307, USA
| | - Kenny Chen
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Ave, Cambridge, MA, 02139-4307, USA
| | - Ngoc-Duc Doan
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Ave, Cambridge, MA, 02139-4307, USA
| | - Matthew D Shoulders
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Ave, Cambridge, MA, 02139-4307, USA.
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52
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Chaperonin 60 sustains osteoblast autophagy and counteracts glucocorticoid aggravation of osteoporosis by chaperoning RPTOR. Cell Death Dis 2018; 9:938. [PMID: 30224697 PMCID: PMC6141469 DOI: 10.1038/s41419-018-0970-6] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2018] [Revised: 08/19/2018] [Accepted: 08/20/2018] [Indexed: 11/29/2022]
Abstract
Glucocorticoid excess medication interrupts osteoblast homeostasis and exacerbates bone mass and microstructure loss ramping up the pathogenesis of osteoporotic disorders. Heat shock protein 60 (HSP60) is found to maintain protein function within cellular microenvironment upon encountering detrimental stress. In this study, we revealed that supraphysiological dexamethasone decreased HSP60 expression along with deregulated autophagy in osteoblasts cultures. This chaperonin is required to sustain autophagic markers Atg4, and Atg12 expression, LC3-II conversion, and autophagic puncta formation, and alleviated the glucocorticoid-induced loss of osteogenic gene expression and mineralized matrix accumulation. Regulator-associated protein of mTOR complex 1 (RPTOR) existed in HSP60 immunoprecipitate contributing to the HSP60-promoted autophagy and osteogenesis because knocking down RPTOR impaired autophagic influx and osteogenic activity. HSP60 shielded from RPTOR dysfunction by reducing the glucocorticoid-induced RPTOR de-phosphorylation, aggregation, and ubiquitination. In vivo, forced RPTOR expression attenuated the methylprednisolone-induced loss of osteoblast autophagy, bone mass, and trabecular microstructure in mice. HSP60 transgenic mice displayed increased cortical bone, mineral acquisition, and osteoblast proliferation along with higher osteogenesis of bone marrow mesenchymal cells than those of wild-type mice. HSP60 overexpression retained RPTOR signaling, sustained osteoblast autophagy, and compromised the severity of glucocorticoid-induced bone loss and sparse trabecular histopathology. Taken together, HSP60 is essential to maintain osteoblast autophagy, which facilitates mineralized matrix production. It fends off glucocorticoid-induced osteoblast apoptosis and bone loss by stabilizing RPTOR action to autophagy. This study offers a new insight into the mechanistic by which chaperonin protects against the glucocorticoid-induced osteoblast dysfunction and bone loss.
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53
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Li H, Li D, Ma Z, Qian Z, Kang X, Jin X, Li F, Wang X, Chen Q, Sun H, Wu S. Defective autophagy in osteoblasts induces endoplasmic reticulum stress and causes remarkable bone loss. Autophagy 2018; 14:1726-1741. [PMID: 29962255 PMCID: PMC6135623 DOI: 10.1080/15548627.2018.1483807] [Citation(s) in RCA: 126] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2017] [Revised: 05/15/2018] [Accepted: 05/24/2018] [Indexed: 12/13/2022] Open
Abstract
Macroautophagy/autophagy is a highly regulated process involved in the turnover of cytosolic components, however its pivotal role in maintenance of bone homeostasis remains elusive. In the present study, we investigated the direct role of ATG7 (autophagy related 7) during developmental and remodeling stages in vivo using osteoblast-specific Atg7 conditional knockout (cKO) mice. Atg7 cKO mice exhibited a reduced bone mass at both developmental and adult age. The trabecular bone volume of Atg7 cKO mice was significantly lower than that of controls at 5 months of age. This phenotype was attributed to decreased osteoblast formation and matrix mineralization, accompanied with an increased osteoclast number and the extent of the bone surface covered by osteoclasts as well as an elevated secretion of TNFSF11/RANKL (tumor necrosis factor [ligand] superfamily, member 11), and a decrease in TNFRSF11B/OPG (tumor necrosis factor receptor superfamily, member 11b [osteoprotegerin]). Remarkably, Atg7 deficiency in osteoblasts triggered endoplasmic reticulum (ER) stress, whereas attenuation of ER stress by administration of phenylbutyric acid in vivo abrogated Atg7 ablation-mediated effects on osteoblast differentiation, mineralization capacity and bone formation. Consistently, Atg7 deficiency impeded osteoblast mineralization and promoted apoptosis partially in DDIT3/CHOP (DNA-damage-inducible transcript 3)- and MAPK8/JNK1 (mitogen-activated protein kinase 8)-SMAD1/5/8-dependent manner in vitro, while reconstitution of Atg7 could improve ER stress and restore skeletal balance. In conclusion, our findings provide direct evidences that autophagy plays crucial roles in regulation of bone homeostasis and suggest an innovative therapeutic strategy against skeletal diseases.
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Affiliation(s)
- Huixia Li
- The First Affiliated Hospital of Xi’an Jiaotong University; Key Laboratory of Environment and Genes Related to Diseases, Ministry of Education, Xi’an Jiaotong University Health Science Center, Xi’an, Shaanxi, China
| | - Danhui Li
- The First Affiliated Hospital of Xi’an Jiaotong University; Key Laboratory of Environment and Genes Related to Diseases, Ministry of Education, Xi’an Jiaotong University Health Science Center, Xi’an, Shaanxi, China
| | - Zhengmin Ma
- The First Affiliated Hospital of Xi’an Jiaotong University; Key Laboratory of Environment and Genes Related to Diseases, Ministry of Education, Xi’an Jiaotong University Health Science Center, Xi’an, Shaanxi, China
| | - Zhuang Qian
- Center for Translational Medicine, the First Affiliated Hospital of Xi’an Jiaotong University, Xi’an, Shaanxi, China
| | - Xiaomin Kang
- Center for Translational Medicine, the First Affiliated Hospital of Xi’an Jiaotong University, Xi’an, Shaanxi, China
| | - Xinxin Jin
- Center for Translational Medicine, the First Affiliated Hospital of Xi’an Jiaotong University, Xi’an, Shaanxi, China
| | - Fang Li
- The First Affiliated Hospital of Xi’an Jiaotong University; Key Laboratory of Environment and Genes Related to Diseases, Ministry of Education, Xi’an Jiaotong University Health Science Center, Xi’an, Shaanxi, China
| | - Xinluan Wang
- Translational Medicine R&D Center, Institute of Biomedical and Health Engineering, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China
| | - Qian Chen
- Department of Orthopaedics, Alpert Medical School of Brown University, Rhode Island Hospital, Providence, RI, USA
- Bone and Joint Research Center, the First Affiliated Hospital of Medical School, Frontier Institute of Science and Technology, Xi’an Jiaotong University, Xi’an, Shaanxi, China
| | - Hongzhi Sun
- The First Affiliated Hospital of Xi’an Jiaotong University; Key Laboratory of Environment and Genes Related to Diseases, Ministry of Education, Xi’an Jiaotong University Health Science Center, Xi’an, Shaanxi, China
| | - Shufang Wu
- The First Affiliated Hospital of Xi’an Jiaotong University; Key Laboratory of Environment and Genes Related to Diseases, Ministry of Education, Xi’an Jiaotong University Health Science Center, Xi’an, Shaanxi, China
- Center for Translational Medicine, the First Affiliated Hospital of Xi’an Jiaotong University, Xi’an, Shaanxi, China
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54
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Wang C, Tan Z, Niu B, Tsang KY, Tai A, Chan WCW, Lo RLK, Leung KKH, Dung NWF, Itoh N, Zhang MQ, Chan D, Cheah KSE. Inhibiting the integrated stress response pathway prevents aberrant chondrocyte differentiation thereby alleviating chondrodysplasia. eLife 2018; 7:37673. [PMID: 30024379 PMCID: PMC6053305 DOI: 10.7554/elife.37673] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2018] [Accepted: 07/05/2018] [Indexed: 12/16/2022] Open
Abstract
The integrated stress response (ISR) is activated by diverse forms of cellular stress, including endoplasmic reticulum (ER) stress, and is associated with diseases. However, the molecular mechanism(s) whereby the ISR impacts on differentiation is incompletely understood. Here, we exploited a mouse model of Metaphyseal Chondrodysplasia type Schmid (MCDS) to provide insight into the impact of the ISR on cell fate. We show the protein kinase RNA-like ER kinase (PERK) pathway that mediates preferential synthesis of ATF4 and CHOP, dominates in causing dysplasia by reverting chondrocyte differentiation via ATF4-directed transactivation of Sox9. Chondrocyte survival is enabled, cell autonomously, by CHOP and dual CHOP-ATF4 transactivation of Fgf21. Treatment of mutant mice with a chemical inhibitor of PERK signaling prevents the differentiation defects and ameliorates chondrodysplasia. By preventing aberrant differentiation, titrated inhibition of the ISR emerges as a rationale therapeutic strategy for stress-induced skeletal disorders.
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Affiliation(s)
- Cheng Wang
- School of Biomedical Sciences, University of Hong Kong, Hong Kong, China
| | - Zhijia Tan
- School of Biomedical Sciences, University of Hong Kong, Hong Kong, China
| | - Ben Niu
- School of Biomedical Sciences, University of Hong Kong, Hong Kong, China
| | - Kwok Yeung Tsang
- School of Biomedical Sciences, University of Hong Kong, Hong Kong, China
| | - Andrew Tai
- School of Biomedical Sciences, University of Hong Kong, Hong Kong, China
| | - Wilson C W Chan
- School of Biomedical Sciences, University of Hong Kong, Hong Kong, China
| | - Rebecca L K Lo
- School of Biomedical Sciences, University of Hong Kong, Hong Kong, China
| | - Keith K H Leung
- School of Biomedical Sciences, University of Hong Kong, Hong Kong, China
| | - Nelson W F Dung
- School of Biomedical Sciences, University of Hong Kong, Hong Kong, China
| | - Nobuyuki Itoh
- Graduate School of Pharmaceutical Sciences, University of Kyoto, Kyoto, Japan
| | - Michael Q Zhang
- Department of Biological Sciences, Center for Systems Biology, The University of Texas at Dallas, Richardson, United States.,MOE Key Laboratory of Bioinformatics, Center for Synthetic and Systems Biology, Tsinghua University, Beijing, China
| | - Danny Chan
- School of Biomedical Sciences, University of Hong Kong, Hong Kong, China
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55
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Makareeva E, Sun G, Mirigian LS, Mertz EL, Vera JC, Espinoza NA, Yang K, Chen D, Klein TE, Byers PH, Leikin S. Substitutions for arginine at position 780 in triple helical domain of the α1(I) chain alter folding of the type I procollagen molecule and cause osteogenesis imperfecta. PLoS One 2018; 13:e0200264. [PMID: 29990383 PMCID: PMC6039012 DOI: 10.1371/journal.pone.0200264] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2018] [Accepted: 06/24/2018] [Indexed: 01/30/2023] Open
Abstract
OI is a clinically and genetically heterogeneous disorder characterized by bone fragility. More than 90% of patients are heterozygous for mutations in type I collagen genes, COL1A1 and COL1A2, and a common mutation is substitution for an obligatory glycine in the triple helical Gly-X-Y repeats. Few non-glycine substitutions in the triple helical domain have been reported; most result in Y-position substitutions of arginine by cysteine. Here, we investigated leucine and cysteine substitutions for one Y-position arginine, p.Arg958 (Arg780 in the triple helical domain) of proα1(I) chains that cause mild OI. We compared their effects with two substitutions for glycine located in close proximity. Like substitutions for glycine, those for arginine reduced the denaturation temperature of the whole molecule and caused asymmetric posttranslational overmodification of the chains. Circular dichroism and increased susceptibility to cleavage by MMP1, MMP2 and catalytic domain of MMP1 revealed significant destabilization of the triple helix near the collagenase cleavage site. On a cellular level, we observed slower triple helix folding and intracellular collagen retention, which disturbed the Endoplasmic Reticulum function and affected matrix deposition. Molecular dynamic modeling suggested that Arg780 substitutions disrupt the triple helix structure and folding by eliminating hydrogen bonds of arginine side chains, in addition to preventing HSP47 binding. The pathogenic effects of these non-glycine substitutions in bone are probably caused mostly by procollagen misfolding and its downstream effects.
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Affiliation(s)
- Elena Makareeva
- Section on Physical Biochemistry, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Guoli Sun
- Department of Pathology, University of Washington, Seattle, Washington, United States of America
| | - Lynn S. Mirigian
- Section on Physical Biochemistry, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Edward L. Mertz
- Section on Physical Biochemistry, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Juan C. Vera
- Section on Physical Biochemistry, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Nydea A. Espinoza
- Section on Physical Biochemistry, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Kathleen Yang
- Department of Pathology, University of Washington, Seattle, Washington, United States of America
| | - Diana Chen
- Department of Pathology, University of Washington, Seattle, Washington, United States of America
| | - Teri E. Klein
- Department of Genetics, Stanford University, Palo Alto, California, United States of America
| | - Peter H. Byers
- Department of Pathology, University of Washington, Seattle, Washington, United States of America
- Department of Medicine, Division of Medical Genetics, University of Washington, Seattle, Washington, United States of America
| | - Sergey Leikin
- Section on Physical Biochemistry, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, United States of America
- * E-mail:
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56
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Lindert U, Gnoli M, Maioli M, Bedeschi MF, Sangiorgi L, Rohrbach M, Giunta C. Insight into the Pathology of a COL1A1 Signal Peptide Heterozygous Mutation Leading to Severe Osteogenesis Imperfecta. Calcif Tissue Int 2018; 102:373-379. [PMID: 29101475 PMCID: PMC5818590 DOI: 10.1007/s00223-017-0359-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/25/2017] [Accepted: 10/30/2017] [Indexed: 12/22/2022]
Abstract
Osteogenesis imperfecta or "brittle bone disease" is a congenital disorder of connective tissue causing the bone to break easily. Around 85-90% of cases are due to autosomal dominant mutations in the genes encoding type I collagen, the major organic component of bone. Genotype-phenotype correlations have shown that quantitative defects of collagen type I lead to mild OI, whereas structural defects show a wide clinical range from mild to perinatal lethal. This may partially be explained by the type of amino acid substitution and the relative location in the domain structure. To fully understand the variability of the clinical manifestation and the underlying pathomechanisms, further investigations are required. Here we provide the first biochemical characterization of a mutation at the signal peptide cleavage site of COL1A1, a domain not yet characterized. By steady-state analysis, we observed reduced production of collagen type I. Furthermore, by pulse-chase analysis we detected delayed secretion and partial intracellular retention of collagen I. In the cellular fraction, the electrophoretic migration was abnormal; however, secreted type I collagen showed a normal migration pattern. The intracellular retention of collagen I was confirmed by immunofluorescent staining. Moreover, transmission electron microscopy of cultured fibroblasts revealed enlargement of ER cisternae. These results further support the hypothesis that mechanisms interfering with ER integrity play an important role in the pathology of severe OI.
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Affiliation(s)
- U Lindert
- Connective Tissue Unit, Division of Metabolism and Children's Research Center, University Children's Hospital, Steinwiesstrasse 75, 8032, Zurich, Switzerland
| | - M Gnoli
- Department of Medical Genetics and Skeletal Rare Diseases, Rizzoli Orthopaedic Institute, Bologna, Italy
| | - M Maioli
- Department of Medical Genetics and Skeletal Rare Diseases, Rizzoli Orthopaedic Institute, Bologna, Italy
| | - M F Bedeschi
- Medical Genetics Unit, Fondazione IRCCS Ca'Granda Ospedale Maggiore Policlinico, Milano, Italy
| | - L Sangiorgi
- Department of Medical Genetics and Skeletal Rare Diseases, Rizzoli Orthopaedic Institute, Bologna, Italy
| | - M Rohrbach
- Connective Tissue Unit, Division of Metabolism and Children's Research Center, University Children's Hospital, Steinwiesstrasse 75, 8032, Zurich, Switzerland
| | - C Giunta
- Connective Tissue Unit, Division of Metabolism and Children's Research Center, University Children's Hospital, Steinwiesstrasse 75, 8032, Zurich, Switzerland.
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57
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Besio R, Iula G, Garibaldi N, Cipolla L, Sabbioneda S, Biggiogera M, Marini JC, Rossi A, Forlino A. 4-PBA ameliorates cellular homeostasis in fibroblasts from osteogenesis imperfecta patients by enhancing autophagy and stimulating protein secretion. Biochim Biophys Acta Mol Basis Dis 2018; 1864:1642-1652. [PMID: 29432813 PMCID: PMC5908783 DOI: 10.1016/j.bbadis.2018.02.002] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Revised: 02/06/2018] [Accepted: 02/08/2018] [Indexed: 12/11/2022]
Abstract
The clinical phenotype in osteogenesis imperfecta (OI) is attributed to the dominant negative function of mutant type I collagen molecules in the extracellular matrix, by altering its structure and function. Intracellular retention of mutant collagen has also been reported, but its effect on cellular homeostasis is less characterized. Using OI patient fibroblasts carrying mutations in the α1(I) and α2(I) chains we demonstrate that retained collagen molecules are responsible for endoplasmic reticulum (ER) enlargement and activation of the unfolded protein response (UPR) mainly through the eukaryotic translation initiation factor 2 alpha kinase 3 (PERK) branch. Cells carrying α1(I) mutations upregulate autophagy, while cells with α2(I) mutations only occasionally activate the autodegradative response. Despite the autophagy activation to face stress conditions, apoptosis occurs in all mutant fibroblasts. To reduce cellular stress, mutant fibroblasts were treated with the FDA-approved chemical chaperone 4-phenylbutyric acid. The drug rescues cell death by modulating UPR activation thanks to both its chaperone and histone deacetylase inhibitor abilities. As chaperone it increases general cellular protein secretion in all patients' cells as well as collagen secretion in cells with the most C-terminal mutation. As histone deacetylase inhibitor it enhances the expression of the autophagic gene Atg5 with a consequent stimulation of autophagy. These results demonstrate that the cellular response to ER stress can be a relevant target to ameliorate OI cell homeostasis.
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Affiliation(s)
- Roberta Besio
- Department of Molecular Medicine, Biochemistry Unit, University of Pavia, Pavia 27100, Italy.
| | - Giusy Iula
- Department of Molecular Medicine, Biochemistry Unit, University of Pavia, Pavia 27100, Italy.
| | - Nadia Garibaldi
- Department of Molecular Medicine, Biochemistry Unit, University of Pavia, Pavia 27100, Italy.
| | - Lina Cipolla
- Istituto di Genetica Molecolare, Consiglio Nazionale delle Ricerche, Pavia 27100, Italy.
| | - Simone Sabbioneda
- Istituto di Genetica Molecolare, Consiglio Nazionale delle Ricerche, Pavia 27100, Italy.
| | - Marco Biggiogera
- Department of Biology and Biotechnology, University of Pavia, 27100 Pavia, Italy.
| | - Joan C Marini
- Bone and Extracellular Matrix Branch, NICHD, National Institute of Health, Bethesda, MD 20892, USA.
| | - Antonio Rossi
- Department of Molecular Medicine, Biochemistry Unit, University of Pavia, Pavia 27100, Italy.
| | - Antonella Forlino
- Department of Molecular Medicine, Biochemistry Unit, University of Pavia, Pavia 27100, Italy.
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58
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Gioia R, Tonelli F, Ceppi I, Biggiogera M, Leikin S, Fisher S, Tenedini E, Yorgan TA, Schinke T, Tian K, Schwartz JM, Forte F, Wagener R, Villani S, Rossi A, Forlino A. The chaperone activity of 4PBA ameliorates the skeletal phenotype of Chihuahua, a zebrafish model for dominant osteogenesis imperfecta. Hum Mol Genet 2018; 26:2897-2911. [PMID: 28475764 PMCID: PMC5886106 DOI: 10.1093/hmg/ddx171] [Citation(s) in RCA: 56] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2017] [Accepted: 05/02/2017] [Indexed: 12/21/2022] Open
Abstract
Classical osteogenesis imperfecta (OI) is a bone disease caused by type I collagen mutations and characterized by bone fragility, frequent fractures in absence of trauma and growth deficiency. No definitive cure is available for OI and to develop novel drug therapies, taking advantage of a repositioning strategy, the small teleost zebrafish (Danio rerio) is a particularly appealing model. Its small size, high proliferative rate, embryo transparency and small amount of drug required make zebrafish the model of choice for drug screening studies, when a valid disease model is available. We performed a deep characterization of the zebrafish mutant Chihuahua, that carries a G574D (p.G736D) substitution in the α1 chain of type I collagen. We successfully validated it as a model for classical OI. Growth of mutants was delayed compared with WT. X-ray, µCT, alizarin red/alcian blue and calcein staining revealed severe skeletal deformity, presence of fractures and delayed mineralization. Type I collagen extracted from different tissues showed abnormal electrophoretic migration and low melting temperature. The presence of endoplasmic reticulum (ER) enlargement due to mutant collagen retention in osteoblasts and fibroblasts of mutant fish was shown by electron and confocal microscopy. Two chemical chaperones, 4PBA and TUDCA, were used to ameliorate the cellular stress and indeed 4PBA ameliorated bone mineralization in larvae and skeletal deformities in adult, mainly acting on reducing ER cisternae size and favoring collagen secretion. In conclusion, our data demonstrated that ER stress is a novel target to ameliorate OI phenotype; chemical chaperones such as 4PBA may be, alone or in combination, a new class of molecules to be further investigated for OI treatment.
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Affiliation(s)
- Roberta Gioia
- Department of Molecular Medicine, Biochemistry Unit, University of Pavia, Pavia, Italy
| | - Francesca Tonelli
- Department of Molecular Medicine, Biochemistry Unit, University of Pavia, Pavia, Italy
| | - Ilaria Ceppi
- Department of Molecular Medicine, Biochemistry Unit, University of Pavia, Pavia, Italy
| | - Marco Biggiogera
- Department of Biology and Biotechnology, University of Pavia, Pavia, Italy
| | - Sergey Leikin
- Section on Physical Biochemistry, Eunice Kennedy Shriver NICHD, NIH, Bethesda, MD, USA
| | - Shannon Fisher
- Department of Pharmacology & Experimental Therapeutics, Boston University School of Medicine, Boston, MA, USA
| | - Elena Tenedini
- Center for Genome Research, Department of Medical and Surgical Sciences, University of Modena and Reggio Emilia, Modena, Italy
| | - Timur A Yorgan
- Institute of Osteology and Biomechanic, Center for Experimental Medicine, University of Hamburg, Hamburg, Germany
| | - Thorsten Schinke
- Institute of Osteology and Biomechanic, Center for Experimental Medicine, University of Hamburg, Hamburg, Germany
| | - Kun Tian
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK
| | - Jean-Marc Schwartz
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK
| | - Fabiana Forte
- Medical Faculty, Center for Biochemistry, Center for Molecular Medicine, University of Cologne, Cologne, Germany
| | - Raimund Wagener
- Medical Faculty, Center for Biochemistry, Center for Molecular Medicine, University of Cologne, Cologne, Germany
| | - Simona Villani
- Department of Public Health and Experimental and Forensic Medicine, Unit of Biostatistics and Clinical Epidemiology, University of Pavia, Pavia, Italy
| | - Antonio Rossi
- Department of Molecular Medicine, Biochemistry Unit, University of Pavia, Pavia, Italy
| | - Antonella Forlino
- Department of Molecular Medicine, Biochemistry Unit, University of Pavia, Pavia, Italy
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59
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Lim J, Grafe I, Alexander S, Lee B. Genetic causes and mechanisms of Osteogenesis Imperfecta. Bone 2017; 102:40-49. [PMID: 28232077 PMCID: PMC5607741 DOI: 10.1016/j.bone.2017.02.004] [Citation(s) in RCA: 66] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/30/2016] [Revised: 01/07/2017] [Accepted: 02/11/2017] [Indexed: 12/25/2022]
Abstract
Osteogenesis Imperfecta (OI) is a genetic disorder characterized by various clinical features including bone deformities, low bone mass, brittle bones, and connective tissue manifestations. The predominant cause of OI is due to mutations in the two genes that encode type I collagen. However, recent advances in sequencing technology has led to the discovery of novel genes that are implicated in recessive and dominant OI. These include genes that regulate the post-translational modification, secretion and processing of type I collagen as well as those required for osteoblast differentiation and bone mineralization. As such, OI has become a spectrum of genetic disorders informing about the determinants of both bone quantity and quality. Here we summarize the known genetic causes of OI, animal models that recapitulate the human disease and mechanisms that underlie disease pathogenesis. Additionally, we discuss the effects of disrupted collagen networks on extracellular matrix signaling and its impact on disease progression.
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Affiliation(s)
- Joohyun Lim
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Ingo Grafe
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Stefanie Alexander
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Brendan Lee
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA.
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60
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Little DG, Peacock L, Mikulec K, Kneissel M, Kramer I, Cheng TL, Schindeler A, Munns C. Combination sclerostin antibody and zoledronic acid treatment outperforms either treatment alone in a mouse model of osteogenesis imperfecta. Bone 2017; 101:96-103. [PMID: 28461254 DOI: 10.1016/j.bone.2017.04.016] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/30/2017] [Revised: 04/26/2017] [Accepted: 04/27/2017] [Indexed: 10/19/2022]
Abstract
In this study, we examined the therapeutic potential of anti-Sclerostin Antibody (Scl-Ab) and bisphosphonate treatments for the bone fragility disorder Osteogenesis Imperfecta (OI). Mice with the Amish OI mutation (Col1a2 G610C mice) and control wild type littermates (WT) were treated from week 5 to week 9 of life with (1) saline (control), (2) zoledronic acid given 0.025mg/kg s.c. weekly (ZA), (3) Scl-Ab given 50mg/kg IV weekly (Scl-Ab), or (4) a combination of both (Scl-Ab/ZA). Functional outcomes were prioritized and included bone mineral density (BMD), bone microarchitecture, long bone bending strength, and vertebral compression strength. By dual-energy absorptiometry, Scl-Ab treatment alone had no effect on tibial BMD, while ZA and Scl-Ab/ZA significantly enhanced BMD by week 4 (+16% and +27% respectively, P<0.05). Scl-Ab/ZA treatment also led to increases in cortical thickness and tissue mineral density, and restored the tibial 4-point bending strength to that of control WT mice. In the spine, all treatments increased compression strength over controls, but only the combined group reached the strength of WT controls. Scl-Ab showed greater anabolic effects in the trabecular bone than in cortical bone. In summary, the Scl-Ab/ZA intervention was superior to either treatment alone in this OI mouse model, however further studies are required to establish its efficacy in other preclinical and clinical scenarios.
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Affiliation(s)
- David G Little
- Orthopaedic Research & Biotechnology Unit, The Children's Hospital at Westmead, Sydney, NSW, Australia; Discipline of Paediatrics and Child Health, Faculty of Medicine, University of Sydney, Sydney, NSW, Australia.
| | - Lauren Peacock
- Orthopaedic Research & Biotechnology Unit, The Children's Hospital at Westmead, Sydney, NSW, Australia
| | - Kathy Mikulec
- Orthopaedic Research & Biotechnology Unit, The Children's Hospital at Westmead, Sydney, NSW, Australia
| | - Michaela Kneissel
- Bone Unit, Musculoskeletal Disease Area, Novartis Institutes for BioMedical Research, Basel, Switzerland
| | - Ina Kramer
- Bone Unit, Musculoskeletal Disease Area, Novartis Institutes for BioMedical Research, Basel, Switzerland
| | - Tegan L Cheng
- Orthopaedic Research & Biotechnology Unit, The Children's Hospital at Westmead, Sydney, NSW, Australia; Discipline of Paediatrics and Child Health, Faculty of Medicine, University of Sydney, Sydney, NSW, Australia
| | - Aaron Schindeler
- Orthopaedic Research & Biotechnology Unit, The Children's Hospital at Westmead, Sydney, NSW, Australia; Discipline of Paediatrics and Child Health, Faculty of Medicine, University of Sydney, Sydney, NSW, Australia
| | - Craig Munns
- Orthopaedic Research & Biotechnology Unit, The Children's Hospital at Westmead, Sydney, NSW, Australia; Discipline of Paediatrics and Child Health, Faculty of Medicine, University of Sydney, Sydney, NSW, Australia
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61
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Acidic pH environment induces autophagy in osteoblasts. Sci Rep 2017; 7:46161. [PMID: 28382973 PMCID: PMC5382697 DOI: 10.1038/srep46161] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Accepted: 03/09/2017] [Indexed: 12/22/2022] Open
Abstract
Osteoblasts (OBs) play an important role in bone fracture healing, yet the extreme adverse microenvironment in fracture sites has a negative impact on the survival of OBs. Therefore, it is important to study how OBs behave in the complex fracture microenvironment. Studies have shown that autophagy plays a pivotal role in maintaining cellular homeostasis and defending the cell against adverse microenvironments. In this study we found the induction of autophagy in OBs at femoral bone fracture sites, which may be a result of ischemia, oxidative stress and hypoxia within the local area. At fracture sites a low pH environment also developed. Until now it has been unclear whether the induction of autophagy in osteoblasts is triggered by the acidic pH environment. Therefore, we cultured OBs in vitro in media of different pH values, and found both autophagy and apoptosis increased in OBs in acidic conditions. However, when autophagy inhibitor chloroquine (CQ) was used, apoptosis increased significantly compared with that without CQ. Thus indicating that inhibition of autophagy may promote apoptosis in OBs in an acidic environment, which may provide a new therapeutic strategy to decrease cell apoptosis in OBs through the use of drugs that modulate the autophagic state.
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Yigit S, Yu H, An B, Hamaia S, Farndale RW, Kaplan DL, Lin YS, Brodsky B. Mapping the Effect of Gly Mutations in Collagen on α2β1 Integrin Binding. J Biol Chem 2016; 291:19196-207. [PMID: 27432884 PMCID: PMC5009287 DOI: 10.1074/jbc.m116.726182] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2016] [Indexed: 11/06/2022] Open
Abstract
The replacement of one Gly in the essential repeating tripeptide sequence of the type I collagen triple helix results in the dominant hereditary bone disorder osteogenesis imperfecta. The mechanism leading to pathology likely involves misfolding and autophagy, although it has been hypothesized that some mutations interfere with known collagen interactions. Here, the effect of Gly replacements within and nearby the integrin binding GFPGER sequence was investigated using a recombinant bacterial collagen system. When a six-triplet human type I collagen sequence containing GFPGER was introduced into a bacterial collagen-like protein, this chimeric protein bound to integrin. Constructs with Gly to Ser substitutions within and nearby the inserted human sequence still formed a trypsin-resistant triple helix, suggesting a small local conformational perturbation. Gly to Ser mutations within the two Gly residues in the essential GFPGER sequence prevented integrin binding and cell attachment as predicted from molecular dynamics studies of the complex. Replacement of Gly residues C-terminal to GFPGER did not affect integrin binding. In contrast, Gly replacements N-terminal to the GFPGER sequence, up to four triplets away, decreased integrin binding and cell adhesion. This pattern suggests either an involvement of the triplets N-terminal to GFPGER in initial binding or a propagation of the perturbation of the triple helix C-terminal to a mutation site. The asymmetry in biological consequences relative to the mutation site may relate to the observed pattern of osteogenesis imperfecta mutations near the integrin binding site.
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Affiliation(s)
- Sezin Yigit
- From the Departments of Biomedical Engineering and Chemistry, Tufts University, Medford, Massachusetts 02155 and
| | - Hongtao Yu
- From the Departments of Biomedical Engineering and Chemistry, Tufts University, Medford, Massachusetts 02155 and
| | - Bo An
- From the Departments of Biomedical Engineering and
| | - Samir Hamaia
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, United Kingdom
| | - Richard W Farndale
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, United Kingdom
| | | | - Yu-Shan Lin
- Chemistry, Tufts University, Medford, Massachusetts 02155 and
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Mertz EL, Makareeva E, Mirigian LS, Koon KY, Perosky JE, Kozloff KM, Leikin S. Makings of a brittle bone: Unexpected lessons from a low protein diet study of a mouse OI model. Matrix Biol 2016; 52-54:29-42. [PMID: 27039252 DOI: 10.1016/j.matbio.2016.03.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2016] [Revised: 03/09/2016] [Accepted: 03/09/2016] [Indexed: 12/19/2022]
Abstract
Glycine substitutions in type I collagen appear to cause osteogenesis imperfecta (OI) by disrupting folding of the triple helix, the structure of which requires Gly in every third position. It is less clear, however, whether the resulting bone malformations and fragility are caused by effects of intracellular accumulation of misfolded collagen on differentiation and function of osteoblasts, effects of secreted misfolded collagen on the function of bone matrix, or both. Here we describe a study originally conceived for testing how reducing intracellular accumulation of misfolded collagen would affect mice with a Gly610 to Cys substitution in the triple helical region of the α2(I) chain. To stimulate degradation of misfolded collagen by autophagy, we utilized a low protein diet. The diet had beneficial effects on osteoblast differentiation and bone matrix mineralization, but also affected bone modeling and suppressed overall animal growth. Our more important observations, however, were not related to the diet. They revealed how altered osteoblast function and deficient bone formation by each cell caused by the G610C mutation combined with increased osteoblastogenesis might make the bone more brittle, all of which are common OI features. In G610C mice, increased bone formation surface compensated for reduced mineral apposition rate, resulting in normal cortical area and thickness at the cost of altering cortical modeling process, retaining woven bone, and reducing the ability of bone to absorb energy through plastic deformation. Reduced collagen and increased mineral density in extracellular matrix of lamellar bone compounded the problem, further reducing bone toughness. The latter observations might have particularly important implications for understanding OI pathophysiology and designing more effective therapeutic interventions.
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Affiliation(s)
- E L Mertz
- Section on Physical Biochemistry, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - E Makareeva
- Section on Physical Biochemistry, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - L S Mirigian
- Section on Physical Biochemistry, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - K Y Koon
- Section on Physical Biochemistry, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - J E Perosky
- Department of Orthopaedic Surgery, University of Michigan, Ann Arbor, MI 48109, USA
| | - K M Kozloff
- Department of Orthopaedic Surgery, University of Michigan, Ann Arbor, MI 48109, USA
| | - S Leikin
- Section on Physical Biochemistry, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA.
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