251
|
Mannion S, Mtintsilana A, Posthumus M, van der Merwe W, Hobbs H, Collins M, September AV. Genes encoding proteoglycans are associated with the risk of anterior cruciate ligament ruptures. Br J Sports Med 2014; 48:1640-6. [PMID: 24552666 DOI: 10.1136/bjsports-2013-093201] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
BACKGROUND Genetic variants within genes involved in fibrillogenesis have previously been implicated in anterior cruciate ligament (ACL) injury susceptibility. Proteoglycans also have important functions in fibrillogenesis and maintaining the structural integrity of ligaments. Genes encoding proteoglycans are plausible candidates to be investigated for associations with ACL injury susceptibility; polymorphisms within genes encoding the proteoglycans aggrecan (ACAN), biglycan (BGN), decorin (DCN), fibromodulin (FMOD) and lumican (LUM) were examined. METHODS A case-control genetic association study was conducted. 227 participants with surgically diagnosed ACL ruptures (ACL group) and 234 controls without any history of ACL injury were genotyped for 10 polymorphisms in 5 proteoglycan genes. Inferred haplotypes were constructed for specific regions. RESULTS The G allele of ACAN rs1516797 was significantly under-represented in the controls (p=0.024; OR=0.72; 95% CI 0.55 to 0.96) compared with the ACL group. For DCN rs516115, the GG genotype was significantly over-represented in female controls (p=0.015; OR=9.231; 95%CI 1.16 to 73.01) compared with the ACL group and the AA genotype was significantly under-represented in controls (p=0.013; OR=0.33; 95% CI 0.14 to 0.78) compared with the female non-contact ACL injury subgroup. Haplotype analyses implicated regions overlapping ACAN (rs2351491 C>T-rs1042631 T>C-rs1516797 T>G), BGN (rs1126499 C>T-rs1042103 G>A) and LUM-DCN (rs2268578 T>C-rs13312816 A>T-rs516115 A>G) in ACL injury susceptibility. CONCLUSIONS These independent associations and haplotype analyses suggest that regions within ACAN, BGN, DCN and a region spanning LUM-DCN are associated with ACL injury susceptibility. Taking into account the functions of these genes, it is reasonable to propose that genetic sequence variability within the genes encoding proteoglycans may potentially modulate the ligament fibril properties.
Collapse
Affiliation(s)
- Sasha Mannion
- UCT/MRC Research Unit for Exercise Science and Sports Medicine, Department of Human Biology, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa Division of Human Genetics, Department of Clinical Laboratory Sciences, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Asanda Mtintsilana
- UCT/MRC Research Unit for Exercise Science and Sports Medicine, Department of Human Biology, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Michael Posthumus
- UCT/MRC Research Unit for Exercise Science and Sports Medicine, Department of Human Biology, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa Sports Science Orthopaedic Clinic, Cape Town, South Africa
| | | | - Hayden Hobbs
- Sports Science Orthopaedic Clinic, Cape Town, South Africa
| | - Malcolm Collins
- UCT/MRC Research Unit for Exercise Science and Sports Medicine, Department of Human Biology, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa The South African Medical Research Council, Cape Town, South Africa
| | - Alison V September
- UCT/MRC Research Unit for Exercise Science and Sports Medicine, Department of Human Biology, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| |
Collapse
|
252
|
Myofibroblasts and the extracellular matrix network in post-myocardial infarction cardiac remodeling. Pflugers Arch 2014; 466:1113-27. [PMID: 24519465 PMCID: PMC4033805 DOI: 10.1007/s00424-014-1463-9] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2014] [Accepted: 01/27/2014] [Indexed: 01/17/2023]
Abstract
The cardiac extracellular matrix (ECM) fills the space between cells, supports tissue organization, and transduces mechanical, chemical, and biological signals to regulate homeostasis of the left ventricle (LV). Following myocardial infarction (MI), a multitude of ECM proteins are synthesized to replace myocyte loss and form a reparative scar. Activated fibroblasts (myofibroblasts) are the primary source of ECM proteins, thus playing a key role in cardiac repair. A balanced turnover of ECM through regulation of synthesis by myofibroblasts and degradation by matrix metalloproteinases (MMPs) is critical for proper scar formation. In this review, we summarize the current literature on the roles of myofibroblasts, MMPs, and ECM proteins in MI-induced LV remodeling. In addition, we discuss future research directions that are needed to further elucidate the molecular mechanisms of ECM actions to optimize cardiac repair.
Collapse
|
253
|
Nastase MV, Iozzo RV, Schaefer L. Key roles for the small leucine-rich proteoglycans in renal and pulmonary pathophysiology. Biochim Biophys Acta Gen Subj 2014; 1840:2460-70. [PMID: 24508120 DOI: 10.1016/j.bbagen.2014.01.035] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2013] [Accepted: 01/28/2014] [Indexed: 12/11/2022]
Abstract
BACKGROUND Small leucine-rich proteoglycans (SLRPs) are molecules that have signaling roles in a multitude of biological processes. In this respect, SLRPs play key roles in the evolution of a variety of diseases throughout the human body. SCOPE OF REVIEW We will critically review current developments in the roles of SLRPs in several types of disease of the kidney and lungs. Particular emphasis will be given to the roles of decorin and biglycan, the best characterized members of the SLRP gene family. MAJOR CONCLUSIONS In both renal and pulmonary disorders, SLRPs are essential elements that regulate several pathophysiological processes including fibrosis, inflammation and tumor progression. Decorin has remarkable antifibrotic and antitumorigenic properties and is considered a valuable potential treatment of these diseases. Biglycan can modulate inflammatory processes in lung and renal inflammation and is a potential target in the treatment of inflammatory conditions. GENERAL SIGNIFICANCE SLRPs can serve as either treatment targets or as potential treatment in renal or lung disease. This article is part of a Special Issue entitled Matrix-mediated cell behaviour and properties.
Collapse
Affiliation(s)
- Madalina V Nastase
- Pharmazentrum Frankfurt/ZAFES, Institut für Allgemeine Pharmakologie und Toxikologie, Klinikum der Goethe-Universität Frankfurt am Main, Theodor-Stern-Kai 7, 60590 Frankfurt am Main, Germany.
| | - Renato V Iozzo
- Department of Pathology, Anatomy and Cell Biology, and the Cancer Cell Biology and Signaling Program, Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA 19107, USA.
| | - Liliana Schaefer
- Pharmazentrum Frankfurt/ZAFES, Institut für Allgemeine Pharmakologie und Toxikologie, Klinikum der Goethe-Universität Frankfurt am Main, Theodor-Stern-Kai 7, 60590 Frankfurt am Main, Germany.
| |
Collapse
|
254
|
Satoyoshi R, Kuriyama S, Aiba N, Yashiro M, Tanaka M. Asporin activates coordinated invasion of scirrhous gastric cancer and cancer-associated fibroblasts. Oncogene 2014; 34:650-60. [PMID: 24441039 DOI: 10.1038/onc.2013.584] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2013] [Revised: 10/10/2013] [Accepted: 12/05/2013] [Indexed: 12/21/2022]
Abstract
Scirrhous gastric cancer, which has the worst prognosis among the various types of gastric cancer, is highly invasive and associated with abundant stromal fibroblasts. Although cancer-associated fibroblasts (CAFs) have been proposed to generate a tumor-supportive extracellular matrix that promotes the expansion of this type of cancer, the molecular mechanisms by which CAFs assist cancer cells are not yet fully understood. Here, we show for the first time that Asporin, a small leucine-rich proteoglycan (SLRP), is predominantly expressed in CAFs, and has essential roles in promoting co-invasion of CAFs and cancer cells. CAFs of scirrhous gastric cancer possess high potential for invasion, and invasion by CAFs frequently proceeded invasion by cancer cells, both in vitro and in vivo. Expression of Asporin was induced in fibroblasts by exposure to gastric cancer cells. Asporin secreted from CAFs activates Rac1 via an interaction with CD44 and promotes invasion by CAFs themselves. Moreover, Asporin promoted invasion by neighboring cancer cells, via paracrine effects mediated by activation of the CD44-Rac1 pathway. These results suggest that Asporin is a unique SLRP that promotes progression of scirrhous gastric cancer and is required for coordinated invasion by CAFs and cancer cells. Therefore, Asporin may represent a new therapeutic target molecule for the development of drugs aimed at manipulating the cancer microenvironment.
Collapse
Affiliation(s)
- R Satoyoshi
- Department of Molecular Medicine and Biochemistry, Akita University Graduate School of Medicine, Akita, Japan
| | - S Kuriyama
- Department of Molecular Medicine and Biochemistry, Akita University Graduate School of Medicine, Akita, Japan
| | - N Aiba
- Department of Molecular Medicine and Biochemistry, Akita University Graduate School of Medicine, Akita, Japan
| | - M Yashiro
- Department of Surgical Oncology, Osaka City University Graduate School of Medicine, Abeno-ku, Osaka, Japan
| | - M Tanaka
- Department of Molecular Medicine and Biochemistry, Akita University Graduate School of Medicine, Akita, Japan
| |
Collapse
|
255
|
Interclass small leucine-rich repeat proteoglycan interactions regulate collagen fibrillogenesis and corneal stromal assembly. Matrix Biol 2014; 35:103-11. [PMID: 24447998 DOI: 10.1016/j.matbio.2014.01.004] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2013] [Revised: 01/08/2014] [Accepted: 01/08/2014] [Indexed: 01/22/2023]
Abstract
The corneal stroma is enriched in small leucine-rich proteoglycans (SLRPs), including both class I (decorin and biglycan) and class II (lumican, keratocan and fibromodulin). Transparency is dependent on the assembly and maintenance of a hierarchical stromal organization and SLRPs are critical regulatory molecules. We hypothesize that cooperative interclass SLRP interactions are involved in the regulation of stromal matrix assembly. We test this hypothesis using a compound Bgn(-/0)/Lum(-/-) mouse model and single Lum(-/-) or Bgn(-/0) mouse models and wild type controls. SLRP expression was investigated using immuno-localization and immuno-blots. Structural relationships were defined using ultrastructural and morphometric approaches while transparency was analyzed using in vivo confocal microscopy. The compound Bgn(-/0)/Lum(-/-) corneas demonstrated gross opacity that was not seen in the Bgn(-/0) or wild type corneas and greater than that in the Lum(-/-) mice. The Bgn(-/0)/Lum(-/-) corneas exhibited significantly increased opacity throughout the stroma compared to posterior opacity in the Lum(-/-) and no opacity in Bgn(-/0) or wild type corneas. In the Bgn(-/0)/Lum(-/-) corneas there were abnormal lamellar and fibril structures consistent with the functional deficit in transparency. Lamellar structure was disrupted across the stroma with disorganized fibrils, and altered fibril packing. In addition, fibrils had larger and more heterogeneous diameters with an abnormal structure consistent with abnormal fibril growth. This was not observed in the Bgn(-/0) or wild type corneas and was restricted to the posterior stroma in Lum(-/-) mice. The data demonstrate synergistic interclass regulatory interactions between lumican and biglycan. These interactions are involved in regulating both lamellar structure as well as collagen fibrillogenesis and therefore, corneal transparency.
Collapse
|
256
|
Neill T, Torres A, Buraschi S, Owens RT, Hoek JB, Baffa R, Iozzo RV. Decorin induces mitophagy in breast carcinoma cells via peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α) and mitostatin. J Biol Chem 2014; 289:4952-68. [PMID: 24403067 DOI: 10.1074/jbc.m113.512566] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Tumor cell mitochondria are key biosynthetic hubs that provide macromolecules for cancer progression and angiogenesis. Soluble decorin protein core, hereafter referred to as decorin, potently attenuated mitochondrial respiratory complexes and mitochondrial DNA (mtDNA) in MDA-MB-231 breast carcinoma cells. We found a rapid and dynamic interplay between peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α) and the decorin-induced tumor suppressor gene, mitostatin. This interaction stabilized mitostatin mRNA with concurrent accumulation of mitostatin protein. In contrast, siRNA-mediated abrogation of PGC-1α-blocked decorin-evoked stabilization of mitostatin. Mechanistically, PGC-1α bound MITOSTATIN mRNA to achieve rapid stabilization. These processes were orchestrated by the decorin/Met axis, as blocking the Met-tyrosine kinase or knockdown of Met abrogated these responses. Furthermore, depletion of mitostatin blocked decorin- or rapamycin-evoked mitophagy, increased vascular endothelial growth factor A (VEGFA) production, and compromised decorin-evoked VEGFA suppression. Collectively, our findings underscore the complexity of PGC-1α-mediated mitochondrial homeostasis and establish mitostatin as a key regulator of tumor cell mitophagy and angiostasis.
Collapse
Affiliation(s)
- Thomas Neill
- From the Department of Pathology, Anatomy, and Cell Biology and the Cancer Cell Biology and Signaling Program, Kimmel Cancer Center and
| | | | | | | | | | | | | |
Collapse
|
257
|
Mienaltowski MJ, Birk DE. Structure, physiology, and biochemistry of collagens. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2014; 802:5-29. [PMID: 24443018 DOI: 10.1007/978-94-007-7893-1_2] [Citation(s) in RCA: 143] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Tendons and ligaments are connective tissues that guide motion, share loads, and transmit forces in a manner that is unique to each as well as the anatomical site and biomechanical stresses to which they are subjected. Collagens are the major molecular components of both tendons and ligaments. The hierarchical structure of tendon and its functional properties are determined by the collagens present, as well as their supramolecular organization. There are 28 different types of collagen that assemble into a variety of supramolecular structures. The assembly of specific supramolecular structures is dependent on the interaction with other matrix molecules as well as the cellular elements. Multiple suprastructural assemblies are integrated to form the functional tendon/ligament. This chapter begins with a discussion of collagen molecules. This is followed by a definition of the supramolecular structures assembled by different collagen types. The general principles involved in the assembly of collagen-containing suprastructures are presented focusing on the regulation of tendon collagen fibrillogenesis. Finally, site-specific differences are discussed. While generalizations can be made, differences exist between different tendons as well as between tendons and ligaments. Compositional differences will impact structure that in turn will determine functional differences. Elucidation of the unique physiology and pathophysiology of different tendons and ligaments will require an appreciation of the role compositional differences have on collagen suprastructural assembly, tissue organization, and function.
Collapse
Affiliation(s)
- Michael J Mienaltowski
- Departments of Molecular Pharmacology & Physiology and Orthopaedics & Sports Medicine, University of South Florida, Morsani College of Medicine, 12901 Bruce B. Downs Blvd., MDC8, Tampa, FL, 33612, USA
| | | |
Collapse
|
258
|
Horváth Z, Kovalszky I, Fullár A, Kiss K, Schaff Z, Iozzo RV, Baghy K. Decorin deficiency promotes hepatic carcinogenesis. Matrix Biol 2013; 35:194-205. [PMID: 24361483 DOI: 10.1016/j.matbio.2013.11.004] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2013] [Revised: 11/26/2013] [Accepted: 11/26/2013] [Indexed: 12/16/2022]
Abstract
Hepatocellular carcinoma represents one of the most-rapidly spreading cancers in the world. In the majority of cases, an inflammation-driven fibrosis or cirrhosis precedes the development of the tumor. During malignant transformation, the tumor microenvironment undergoes qualitative and quantitative changes that modulate the behavior of the malignant cells. A key constituent for the hepatic microenvironment is the small leucine-rich proteoglycan decorin, known to interfere with cellular events of tumorigenesis mainly by blocking various receptor tyrosine kinases (RTK) such as EGFR, Met, IGF-IR, PDGFR and VEGFR2. In this study, we characterized cell signaling events evoked by decorin deficiency in two experimental models of hepatocarcinogenesis using thioacetamide or diethyl nitrosamine as carcinogens. Genetic ablation of decorin led to enhanced tumor occurrence as compared to wild-type animals. These findings correlated with decreased levels of the cyclin-dependent kinase inhibitor p21(WAF1/CIP1) and a concurrent elevation in retinoblastoma protein phosphorylation via cyclin dependent kinase 4. Decreased steady state p21(Waf1/Cip1) levels correlated with enhanced expression of transcription factor AP4, a known transcriptional repressor of p21(Waf1/Cip1), and enhanced c-Myc protein levels. In addition, translocation of β-catenin was a typical event in diethyl nitrosamine-evoked tumors. In parallel, decreased phosphorylation of both c-Myc and β-catenin was observed in Dcn(-/-) livers likely due to the hindered GSK3β-mediated targeting of these proteins to proteasomal degradation. We discovered that in a genetic background lacking decorin, four RTKs were constitutively activated (phosphorylated), including three known targets of decorin such as PDGFRα, EGFR, IGF-IR, and a novel RTK MSPR/RON. Our findings provide powerful genetic evidence for a crucial in vivo role of decorin during hepatocarcinogenesis as lack of decorin in the liver and hepatic stroma facilitates experimental carcinogenesis by providing an environment devoid of this potent pan-RTK inhibitor. Thus, our results support future utilization of decorin as an antitumor agent in liver cancer.
Collapse
Affiliation(s)
- Zsolt Horváth
- 1st Department of Pathology and Experimental Cancer Research, Semmelweis University, Budapest, Hungary
| | - Ilona Kovalszky
- 1st Department of Pathology and Experimental Cancer Research, Semmelweis University, Budapest, Hungary
| | - Alexandra Fullár
- 1st Department of Pathology and Experimental Cancer Research, Semmelweis University, Budapest, Hungary
| | - Katalin Kiss
- 1st Department of Pathology and Experimental Cancer Research, Semmelweis University, Budapest, Hungary
| | - Zsuzsa Schaff
- 2nd Department of Pathology, Semmelweis University, Budapest, Hungary
| | - Renato V Iozzo
- Department of Pathology, Anatomy, and Cell Biology, and the Cancer Cell Biology and Signaling Program, Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA, USA
| | - Kornélia Baghy
- 1st Department of Pathology and Experimental Cancer Research, Semmelweis University, Budapest, Hungary.
| |
Collapse
|
259
|
Yamanaka O, Yuan Y, Coulson-Thomas VJ, Gesteira TF, Call MK, Zhang Y, Zhang J, Chang SH, Xie C, Liu CY, Saika S, Jester JV, Kao WWY. Lumican binds ALK5 to promote epithelium wound healing. PLoS One 2013; 8:e82730. [PMID: 24367547 PMCID: PMC3867403 DOI: 10.1371/journal.pone.0082730] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2013] [Accepted: 11/06/2013] [Indexed: 12/30/2022] Open
Abstract
Lumican (Lum), a small leucine-rich proteoglycan (SLRP) family member, has multiple matricellular functions both as an extracellular matrix component and as a matrikine regulating cell proliferation, gene expression and wound healing. To date, no cell surface receptor has been identified to mediate the matrikine functions of Lum. This study aimed to identify a perspective receptor that mediates Lum effects on promoting wound healing. Transforming growth factor-β receptor 1 (ALK5) was identified as a potential Lum-interacting protein through in silico molecular docking and molecular dynamics. This finding was verified by biochemical pull-down assays. Moreover, the Lum function on wound healing was abrogated by an ALK5-specific chemical inhibitor as well as by ALK5 shRNAi. Finally, we demonstrated that eukaryote-specific post-translational modifications are not required for the wound healing activity of Lum, as recombinant GST-Lum fusion proteins purified from E. coli and a chemically synthesized LumC13 peptide (the last C-terminal 13 amino acids of Lum) have similar effects on wound healing in vitro and in vivo.
Collapse
Affiliation(s)
- Osamu Yamanaka
- Deparment of Ophthalmology, University of Cincinnati, Cincinnati, Ohio, United States of America
| | - Yong Yuan
- Deparment of Ophthalmology, University of Cincinnati, Cincinnati, Ohio, United States of America
| | | | - Tarsis Ferreira Gesteira
- Division of Developmental Biology, Cincinnati Children's Hospital Research Foundation, Cincinnati, Ohio, United States of America
| | - Mindy K. Call
- Deparment of Ophthalmology, University of Cincinnati, Cincinnati, Ohio, United States of America
| | - Yujin Zhang
- Deparment of Ophthalmology, University of Cincinnati, Cincinnati, Ohio, United States of America
| | - Jianhua Zhang
- Deparment of Ophthalmology, University of Cincinnati, Cincinnati, Ohio, United States of America
| | - Shao-Hsuan Chang
- Deparment of Ophthalmology, University of Cincinnati, Cincinnati, Ohio, United States of America
| | - Changchun Xie
- Department of Environmental Health, University of Cincinnati, Cincinnati, Ohio, United States of America
| | - Chia-Yang Liu
- Deparment of Ophthalmology, University of Cincinnati, Cincinnati, Ohio, United States of America
| | - Shizuya Saika
- Department of Ophthalmology, Wakayama Medical College, 811-1 Kimiidera, Wakayama, Japan
| | - James V. Jester
- Gavin Herbert Eye Institute, Ophthalmology, University of California Irvine, Irvine, California, United States of America
| | - Winston W-Y Kao
- Deparment of Ophthalmology, University of Cincinnati, Cincinnati, Ohio, United States of America
- * E-mail:
| |
Collapse
|
260
|
Islam M, Gor J, Perkins SJ, Ishikawa Y, Bächinger HP, Hohenester E. The concave face of decorin mediates reversible dimerization and collagen binding. J Biol Chem 2013; 288:35526-33. [PMID: 24169694 PMCID: PMC3853298 DOI: 10.1074/jbc.m113.504530] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Decorin, the prototypical small leucine-rich proteoglycan, binds to collagen and thereby regulates collagen assembly into fibrils. The crystal structure of the decorin core protein revealed a tight dimer formed by the association of two monomers via their concave faces (Scott, P. G., McEwan, P. A., Dodd, C. M., Bergmann, E. M., Bishop, P. N., and Bella, J. (2004) Proc. Natl. Acad. Sci. U.S.A. 101, 15633–15638). Whether decorin binds collagen as a dimer has been controversial. Using analytical ultracentrifugation, we determined a dissociation constant of 1.37 ± 0.30 μm for the mouse decorin dimer. Dimerization could be abolished by engineering glycosylation sites into the dimer interface; other interface mutants remained dimeric. The monomeric mutants were as stable as wild-type decorin in thermal unfolding experiments. Mutations on the concave face of decorin abolished collagen binding regardless of whether the mutant proteins retained the ability to dimerize or not. We conclude that the concave face of decorin mediates collagen binding and that the dimer therefore must dissociate to bind collagen.
Collapse
Affiliation(s)
- Mehwaesh Islam
- From the Department of Life Sciences, Imperial College London, London SW7 2AZ, United Kingdom
| | | | | | | | | | | |
Collapse
|
261
|
Dunkman AA, Buckley MR, Mienaltowski MJ, Adams SM, Thomas SJ, Satchell L, Kumar A, Pathmanathan L, Beason DP, Iozzo RV, Birk DE, Soslowsky LJ. The tendon injury response is influenced by decorin and biglycan. Ann Biomed Eng 2013; 42:619-30. [PMID: 24072490 DOI: 10.1007/s10439-013-0915-2] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2013] [Accepted: 09/16/2013] [Indexed: 11/24/2022]
Abstract
Defining the constituent regulatory molecules in tendon is critical to understanding the process of tendon repair and instructive to the development of novel treatment modalities. The purpose of this study is to define the structural, expressional, and mechanical changes in the tendon injury response, and elucidate the roles of two class I small leucine-rich proteoglycans (SLRPs). We utilized biglycan-null, decorin-null and wild type mice with an established patellar tendon injury model. Mechanical testing demonstrated functional changes associated with injury and the incomplete recapitulation of mechanical properties after 6 weeks. In addition, SLRP deficiency influenced the mechanical properties with a marked lack of improvement between 3 and 6 weeks in decorin-null tendons. Morphological analyses of the injury response and role of SLRPs demonstrated alterations in cell density and shape as well as collagen alignment and fibril structure resulting from injury. SLRP gene expression was studied using RT-qPCR with alterations in expression associated with the injured tendons. Our results show that in the absence of biglycan initial healing may be impaired while in the absence of decorin later healing is clearly diminished. This suggests that biglycan and decorin may have sequential roles in the tendon response to injury.
Collapse
Affiliation(s)
- Andrew A Dunkman
- The McKay Orthopaedic Research Laboratory, University of Pennsylvania, 424 Stemmler Hall, 3450 Hamilton Walk, Philadelphia, PA, 19104, USA
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
262
|
Stamov DR, Müller A, Wegrowski Y, Brezillon S, Franz CM. Quantitative analysis of type I collagen fibril regulation by lumican and decorin using AFM. J Struct Biol 2013; 183:394-403. [DOI: 10.1016/j.jsb.2013.05.022] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2013] [Revised: 05/29/2013] [Accepted: 05/30/2013] [Indexed: 10/26/2022]
|
263
|
Intracellularly-retained decorin lacking the C-terminal ear repeat causes ER stress: a cell-based etiological mechanism for congenital stromal corneal dystrophy. THE AMERICAN JOURNAL OF PATHOLOGY 2013; 183:247-56. [PMID: 23685109 DOI: 10.1016/j.ajpath.2013.04.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2013] [Revised: 03/27/2013] [Accepted: 04/01/2013] [Indexed: 12/15/2022]
Abstract
Decorin, a small leucine-rich proteoglycan (SLRP), is involved in the pathophysiology of human congenital stromal corneal dystrophy (CSCD). This disease is characterized by corneal opacities and vision impairment. In reported cases, the human gene encoding decorin contains point mutations in exon 10, generating a truncated form of decorin lacking the C-terminal 33 amino acid residues. We have previously described a transgenic mouse model carrying a similar mutation in the decorin gene that leads to an ocular phenotype characterized by corneal opacities identical to CSCD in humans. We have also identified abnormal synthesis and secretion of various SLRPs in mutant mouse corneas. In the present study, we found that mutant C-terminal truncated decorin was retained in the cytoplasm of mouse keratocytes in vivo and of transfected human embryonic kidney cells. This resulted in endoplasmic reticulum stress and an unfolded protein response. Thus, we propose a novel cell-based mechanism underlying CSCD in which a truncated SLRP protein core is retained intracellularly, its accumulation triggering endoplasmic reticulum stress that results in abnormal SLRP synthesis and secretion, which ultimately affects stromal structure and corneal transparency.
Collapse
|
264
|
Buckley MR, Huffman GR, Iozzo RV, Birk DE, Soslowsky LJ. The location-specific role of proteoglycans in the flexor carpi ulnaris tendon. Connect Tissue Res 2013; 54:367-73. [PMID: 23941206 PMCID: PMC4406324 DOI: 10.3109/03008207.2013.832232] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Tendons like the flexor carpi ulnaris (FCU) that contain region-specific distributions of proteoglycans (PGs) as a result of the heterogeneous, multi-axial loads they are subjected to in vivo provide valuable models for understanding structure-function relationships in connective tissues. However, the contributions of specific PGs to FCU tendon mechanical properties are unknown. Therefore, the objective of this study was to determine how the location-dependent, viscoelastic mechanical properties of the FCU tendon are impacted individually by PG-associated glycosaminoglycans (GAGs) and by two small leucine-rich proteoglycans (SLRPs), biglycan and decorin. Full length FCU tendons from biglycan- and decorin-null mice were compared to wild-type (WT) mice to evaluate the effects of specific SLRPs, while chondroitinase ABC digestion of isolated specimens removed from the tendon midsubstance was used to determine how chondroitin/dermatan sulfate (CS/DS) GAGs impact mechanics in mature FCU tendons. A novel combined genetic knockout/digestion technique also was employed to compare SLRP-null and WT tendons in the absence of CS/DS GAGs that may impact properties in the mature state. In all genotypes, mechanical properties in the FCU tendon midsubstance were not affected by GAG digestion. Full-length tendons exhibited complex, multi-axial deformation under tension that may be associated with their in vivo loading environment. Mechanical properties were adversely affected by the absence of biglycan, and a decreased modulus localized in the center of the tendon was measured. These results help elucidate the role that local alterations in PG levels may play in processes that adversely impact tendon functionality including injury and pathology.
Collapse
Affiliation(s)
- Mark R. Buckley
- Department of Orthopaedic Research, University of Pennsylvania, Philadelphia, PA
| | - George R. Huffman
- Department of Orthopaedic Research, University of Pennsylvania, Philadelphia, PA
| | - Renato V. Iozzo
- Department of Pathology and Cell Biology, Thomas Jefferson University, Philadelphia, PA
| | - David E. Birk
- Department of Molecular Pharmacology and Physiology, University of South Florida, Tampa, FL
| | - Louis J. Soslowsky
- Department of Orthopaedic Research, University of Pennsylvania, Philadelphia, PA,Corresponding author: Louis J Soslowsky, PhD, McKay Orthopaedic Research Laboratory, Department of Orthopaedic Surgery, University of Pennsylvania, 424 Stemmler Hall, 36th Street and Hamilton Walk, Philadelphia, PA 19104-6081, Phone: 215-898-8653; Fax: 2 215-573-2133;
| |
Collapse
|