The Experts below are selected from a list of 1386 Experts worldwide ranked by ideXlab platform
Ake Oldberg - One of the best experts on this subject based on the ideXlab platform.
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Fibromodulin deficiency reduces collagen structural network but not glycosaminoglycan content in a syngeneic model of colon carcinoma
PLOS ONE, 2017Co-Authors: Olof P Olsson, Sebastian Kalamajski, Ake Oldberg, Marco Maccarana, Kristofer RubinAbstract:Tumor barrier function in carcinoma represents a major challenge to treatment and is therefore an attractive target for increasing drug delivery. Variables related to tumor barrier include aberrant blood vessels, high interstitial fluid pressure, and the composition and structure of the extracellular matrix. One of the proteins associated with dense extracellular matrices is Fibromodulin, a collagen fibrillogenesis modulator expressed in tumor stroma but scarce in normal loose connective tissues. Here, we investigated the effects of Fibromodulin on stroma ECM in a syngeneic murine colon carcinoma model. We show that Fibromodulin deficiency decreased collagen fibril thickness but glycosaminoglycan content and composition were unchanged. Furthermore, vascular density, pericyte coverage and macrophage amount were unaffected. Fibromodulin can therefore be a unique effector of dense collagen matrix assembly in tumor stroma and, without affecting other major matrix components or the cellular composition, can function as a main agent in tumor barrier function.
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increased c telopeptide cross linking of tendon type i collagen in Fibromodulin deficient mice
Journal of Biological Chemistry, 2014Co-Authors: Sebastian Kalamajski, Viveka Tillgren, Mary Ann Weis, Ake Oldberg, Kristofer Rubin, Jyoti Rai, Cuiping Liu, David R EyreAbstract:The controlled assembly of collagen monomers into fibrils, with accompanying intermolecular cross-linking by lysyl oxidase-mediated bonds, is vital to the structural and mechanical integrity of connective tissues. This process is influenced by collagen-associated proteins, including small leucine-rich proteins (SLRPs), but the regulatory mechanisms are not well understood. Deficiency in Fibromodulin, an SLRP, causes abnormal collagen fibril ultrastructure and decreased mechanical strength in mouse tendons. In this study, Fibromodulin deficiency rendered tendon collagen more resistant to nonproteolytic extraction. The collagen had an increased and altered cross-linking pattern at an early stage of fibril formation. Collagen extracts contained a higher proportion of stably cross-linked α1(I) chains as a result of their C-telopeptide lysines being more completely oxidized to aldehydes. The findings suggest that Fibromodulin selectively affects the extent and pattern of lysyl oxidase-mediated collagen cross-linking by sterically hindering access of the enzyme to telopeptides, presumably through binding to the collagen. Such activity implies a broader role for SLRP family members in regulating collagen cross-linking placement and quantity.
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Fibromodulin deficiency reduces low density lipoprotein accumulation in atherosclerotic plaques in apolipoprotein e null mice
Arteriosclerosis Thrombosis and Vascular Biology, 2013Co-Authors: Annelie Shami, Sebastian Kalamajski, Ake Oldberg, Jan Nilsson, Renata Gustafsson, Rob Krams, Dolf Segers, Uwe Rauch, Gunnel Roos, Anna HultgardhnilssonAbstract:Objective— The aim of this study was to analyze how an altered collagen structure affects development of atherosclerotic plaques. Methods and Results— Fibromodulin-null mice develop an abnormal collagen fibril structure. In apolipoprotein E (ApoE)-null and ApoE/Fibromodulin-null mice, a shear stress-modifying carotid artery cast induced formation of atherosclerotic plaques of different phenotypes; inflammatory in low-shear stress regions and fibrous in oscillatory shear stress regions. Electron microscopy showed that collagen fibrils were thicker and more heterogeneous in oscillatory shear stress lesions from ApoE/Fibromodulin-null mice. Low-shear stress lesions were smaller in ApoE/Fibromodulin-null mice and contained less lipids. Total plaque burden in aortas stained en face with Oil Red O, as well as lipid accumulation in aortic root lesions, was also decreased in ApoE/Fibromodulin-null mice. In addition, lipid accumulation in RAW264.7 macrophages cultured on Fibromodulin-deficient extracellular matrix was decreased, whereas levels of interleukin-6 and -10 were increased. Our results show that an abnormal plaque collagen fibril structure can influence atherosclerotic plaque development. Conclusion— The present findings suggest a more complex role for collagen in plaque stability than previously anticipated, in that it may promote lipid-accumulation and inflammation at the same time as it provides mechanical stability.
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Fibromodulin regulates collagen fibrillogenesis during peripheral corneal development
Developmental Dynamics, 2010Co-Authors: Shoujun Chen, Ake Oldberg, Shukti Chakravarti, David E BirkAbstract:Fibromodulin regulates collagen fibrillogenesis, but its existence/role(s) in the cornea is controversial. We hypothesize that Fibromodulin regulates fibrillogenesis during postnatal development of the anterior eye. Fibromodulin is weakly expressed in the limbus at post-natal day (P) 4, increases and extends into the central cornea at P14, becomes restricted to the limbus at P30, and decreases at P60. This differential spatial and temporal expression of Fibromodulin is coordinated with emmetropization; the developmental increase in axial length and globe size. Genetic analysis demonstrated that Fibromodulin regulates fibrillogenesis in a region-specific manner. At the limbus, Fibromodulin is dominant in regulating fibril growth during postnatal development. In the posterior peripheral cornea, cooperative interactions of Fibromodulin and lumican regulate fibrillogenesis. These data indicate that Fibromodulin plays important roles in the regulation of region-specific fibrillogenesis required for the integration of the corneal and scleral matrices and sulcus development required for establishment of the visual axis.
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biglycan and Fibromodulin have essential roles in regulating chondrogenesis and extracellular matrix turnover in temporomandibular joint osteoarthritis
American Journal of Pathology, 2010Co-Authors: Mildred C Embree, Ake Oldberg, Tina M Kilts, Mitsuaki Ono, Colette A Inkson, Fatima N Syedpicard, Morten A Karsdal, Marian F YoungAbstract:The temporomandibular joint is critical for jaw movements and allows for mastication, digestion of food, and speech. Temporomandibular joint osteoarthritis is a degenerative disease that is marked by permanent cartilage destruction and loss of extracellular matrix (ECM). To understand how the ECM regulates mandibular condylar chondrocyte (MCC) differentiation and function, we used a genetic mouse model of temporomandibular joint osteoarthritis that is deficient in two ECM proteins, biglycan and Fibromodulin (Bgn(-/0)Fmod(-/-)). Given the unavailability of cell lines, we first isolated primary MCCs and found that they were phenotypically unique from hyaline articular chondrocytes isolated from the knee joint. Using Bgn(-/0) Fmod(-/-) MCCs, we discovered the early basis for temporomandibular joint osteoarthritis arises from abnormal and accelerated chondrogenesis. Transforming growth factor (TGF)-beta1 is a growth factor that is critical for chondrogenesis and binds to both biglycan and Fibromodulin. Our studies revealed the sequestration of TGF-beta1 was decreased within the ECM of Bgn(-/0) Fmod(-/-) MCCs, leading to overactive TGF-beta1 signal transduction. Using an explant culture system, we found that overactive TGF-beta1 signals induced chondrogenesis and ECM turnover in this model. We demonstrated for the first time a comprehensive study revealing the importance of the ECM in maintaining the mandibular condylar cartilage integrity and identified biglycan and Fibromodulin as novel key players in regulating chondrogenesis and ECM turnover during temoporomandibular joint osteoarthritis pathology.
Sebastian Kalamajski - One of the best experts on this subject based on the ideXlab platform.
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Fibromodulin deficiency reduces collagen structural network but not glycosaminoglycan content in a syngeneic model of colon carcinoma
PLOS ONE, 2017Co-Authors: Olof P Olsson, Sebastian Kalamajski, Ake Oldberg, Marco Maccarana, Kristofer RubinAbstract:Tumor barrier function in carcinoma represents a major challenge to treatment and is therefore an attractive target for increasing drug delivery. Variables related to tumor barrier include aberrant blood vessels, high interstitial fluid pressure, and the composition and structure of the extracellular matrix. One of the proteins associated with dense extracellular matrices is Fibromodulin, a collagen fibrillogenesis modulator expressed in tumor stroma but scarce in normal loose connective tissues. Here, we investigated the effects of Fibromodulin on stroma ECM in a syngeneic murine colon carcinoma model. We show that Fibromodulin deficiency decreased collagen fibril thickness but glycosaminoglycan content and composition were unchanged. Furthermore, vascular density, pericyte coverage and macrophage amount were unaffected. Fibromodulin can therefore be a unique effector of dense collagen matrix assembly in tumor stroma and, without affecting other major matrix components or the cellular composition, can function as a main agent in tumor barrier function.
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structural and functional analysis of two small leucine rich repeat proteoglycans Fibromodulin and chondroadherin
Matrix Biology, 2017Co-Authors: Patricia Paracuellos, Sebastian Kalamajski, Dominique Bihan, Arkadiusz Bonna, Richard W Farndale, Erhard HohenesterAbstract:Abstract The small leucine-rich proteoglycans (SLRPs) are important regulators of extracellular matrix assembly and cell signalling. We have determined crystal structures at ~ 2.2 A resolution of human Fibromodulin and chondroadherin, two collagen-binding SLRPs. Their overall fold is similar to that of the prototypical SLRP, decorin, but unlike decorin neither Fibromodulin nor chondroadherin forms a stable dimer. A previously identified binding site for integrin α2β1 maps to an α-helix in the C-terminal cap region of chondroadherin. Interrogation of the Collagen Toolkits revealed a unique binding site for chondroadherin in collagen II, and no binding to collagen III. A triple-helical peptide containing the sequence GAOGPSGFQGLOGPOGPO (O is hydroxyproline) forms a stable complex with chondroadherin in solution. In fibrillar collagen I and II, this sequence is aligned with the collagen cross-linking site KGHR, suggesting a role for chondroadherin in cross-linking.
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the tyrosine sulfate domain of Fibromodulin binds collagen and enhances fibril formation
Journal of Biological Chemistry, 2016Co-Authors: Viveka Tillgren, Patrik Onnerfjord, Sebastian Kalamajski, Matthias Morgelin, Anders AspbergAbstract:Small leucine-rich proteoglycans interact with other extracellular matrix proteins and are important regulators of matrix assembly. Fibromodulin has a key role in connective tissues, binding collagen through two identified binding sites in its leucine-rich repeat domain and regulating collagen fibril formation in vitro and in vivo Some nine tyrosine residues in the Fibromodulin N-terminal domain are O-sulfated, a posttranslational modification often involved in protein interactions. The N-terminal domain mimics heparin, binding proteins with clustered basic amino acid residues. Because heparin affects collagen fibril formation, we investigated whether tyrosine sulfate is involved in Fibromodulin interactions with collagen. Using full-length Fibromodulin and its N-terminal tyrosine-sulfated domain purified from tissue, as well as recombinant Fibromodulin fragments, we found that the N-terminal domain binds collagen. The tyrosine-sulfated domain and the leucine-rich repeat domain both bound to three specific sites along the collagen type I molecule, at the N terminus and at 100 and 220 nm from the N terminus. The N-terminal domain shortened the collagen fibril formation lag phase and tyrosine sulfation was required for this effect. The isolated leucine-rich repeat domain inhibited the fibril formation rate, and full-length Fibromodulin showed a combination of these effects. The fibrils formed in the presence of Fibromodulin or its fragments showed more organized structure. Fibromodulin and its tyrosine sulfate domain remained bound on the formed fiber. Taken together, this suggests a novel, regulatory function for tyrosine sulfation in collagen interaction and control of fibril formation. (Less)
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The Tyrosine Sulfate Domain of Fibromodulin Binds Collagen and Enhances Fibril Formation.
The Journal of biological chemistry, 2016Co-Authors: Viveka Tillgren, Sebastian Kalamajski, Matthias Morgelin, Anders AspbergAbstract:Small leucine-rich proteoglycans interact with other extracellular matrix proteins and are important regulators of matrix assembly. Fibromodulin has a key role in connective tissues, binding collagen through two identified binding sites in its leucine-rich repeat domain and regulating collagen fibril formation in vitro and in vivo Some nine tyrosine residues in the Fibromodulin N-terminal domain are O-sulfated, a posttranslational modification often involved in protein interactions. The N-terminal domain mimics heparin, binding proteins with clustered basic amino acid residues. Because heparin affects collagen fibril formation, we investigated whether tyrosine sulfate is involved in Fibromodulin interactions with collagen. Using full-length Fibromodulin and its N-terminal tyrosine-sulfated domain purified from tissue, as well as recombinant Fibromodulin fragments, we found that the N-terminal domain binds collagen. The tyrosine-sulfated domain and the leucine-rich repeat domain both bound to three specific sites along the collagen type I molecule, at the N terminus and at 100 and 220 nm from the N terminus. The N-terminal domain shortened the collagen fibril formation lag phase and tyrosine sulfation was required for this effect. The isolated leucine-rich repeat domain inhibited the fibril formation rate, and full-length Fibromodulin showed a combination of these effects. The fibrils formed in the presence of Fibromodulin or its fragments showed more organized structure. Fibromodulin and its tyrosine sulfate domain remained bound on the formed fiber. Taken together, this suggests a novel, regulatory function for tyrosine sulfation in collagen interaction and control of fibril formation.
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Fibromodulin interacts with collagen cross linking sites and activates lysyl oxidase
Journal of Biological Chemistry, 2016Co-Authors: Sebastian Kalamajski, Dominique Bihan, Arkadiusz Bonna, Kristofer Rubin, Richard W FarndaleAbstract:The hallmark of fibrotic disorders is a highly cross-linked and dense collagen matrix, a property driven by the oxidative action of lysyl oxidase. Other fibrosis-associated proteins also contribute to the final collagen matrix properties, one of which is Fibromodulin. Its interactions with collagen affect collagen cross-linking, packing, and fibril diameter. We investigated the possibility that a specific relationship exists between Fibromodulin and lysyl oxidase, potentially imparting a specific collagen matrix phenotype. We mapped the Fibromodulin-collagen interaction sites using the collagen II and III Toolkit peptide libraries. Fibromodulin interacted with the peptides containing the known collagen cross-linking sites and the MMP-1 cleavage site in collagens I and II. Interestingly, the interaction sites are closely aligned within the quarter-staggered collagen fibril, suggesting a multivalent interaction between Fibromodulin and several collagen helices. Furthermore, we detected an interaction between Fibromodulin and lysyl oxidase (a major collagen cross-linking enzyme) and mapped the interaction site to 12 N-terminal amino acids on Fibromodulin. This interaction also increases the activity of lysyl oxidase. Together, the data suggest a Fibromodulin-modulated collagen cross-linking mechanism where Fibromodulin binds to a specific part of the collagen domain and also forms a complex with lysyl oxidase, targeting the enzyme toward specific cross-linking sites.
David E Birk - One of the best experts on this subject based on the ideXlab platform.
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Fibromodulin regulates collagen fibrillogenesis during peripheral corneal development
Developmental Dynamics, 2010Co-Authors: Shoujun Chen, Ake Oldberg, Shukti Chakravarti, David E BirkAbstract:Fibromodulin regulates collagen fibrillogenesis, but its existence/role(s) in the cornea is controversial. We hypothesize that Fibromodulin regulates fibrillogenesis during postnatal development of the anterior eye. Fibromodulin is weakly expressed in the limbus at post-natal day (P) 4, increases and extends into the central cornea at P14, becomes restricted to the limbus at P30, and decreases at P60. This differential spatial and temporal expression of Fibromodulin is coordinated with emmetropization; the developmental increase in axial length and globe size. Genetic analysis demonstrated that Fibromodulin regulates fibrillogenesis in a region-specific manner. At the limbus, Fibromodulin is dominant in regulating fibril growth during postnatal development. In the posterior peripheral cornea, cooperative interactions of Fibromodulin and lumican regulate fibrillogenesis. These data indicate that Fibromodulin plays important roles in the regulation of region-specific fibrillogenesis required for the integration of the corneal and scleral matrices and sulcus development required for establishment of the visual axis.
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ocular and scleral alterations in gene targeted lumican Fibromodulin double null mice
Investigative Ophthalmology & Visual Science, 2003Co-Authors: Shukti Chakravarti, L Roberts, Inna Chervoneva, Ake Oldberg, J. Paul, David E BirkAbstract:PURPOSE: To elucidate the role of leucine-rich proteoglycans lumican and Fibromodulin in the sclera. METHODS: Lumican- and Fibromodulin-null heterozygous mice were intercrossed to obtain wild-type (Lum(+/+)Fmod(+/+)), lumican-null (Lum(-/-)Fmod(+/+)), Fibromodulin-null (Lum(+/+)Fmod(-/-)), and double-null (Lum(-/-)Fmod(-/-)) littermates. Axial length was measured on enucleated whole eyes, and ocular structural changes were examined by histology. The morphology of collagen fibrils in the sclera was examined by transmission electron microscopy (TEM). RESULTS: Compared with the ocular axial length in wild type mice, the axial length was increased by 10% in Lum(-/-)Fmod(-/-) (P = 0.02) mice. Retinal detachment was frequent in the double-null and rare in the lumican-null animals. Compared with the wild-type sclera, the sclera in all null mutants was significantly thinner with fewer lamellae (P < 0.05). The double-null sclera contained abnormally large-diameter (120-160 nm) and small-diameter (30-60 nm) collagen fibrils, whereas the Fibromodulin-null sclera was enriched for the small-diameter fibrils. The collagen fibril diameter distribution in the lumican-null sclera was similar to that of the wild-type. CONCLUSIONS: An increase in small-diameter fibrils in the Fibromodulin-null sclera suggests a key role for Fibromodulin in the maturation and assembly of scleral collagen fibrils. That fibril diameter distribution in the lumican-null sclera was comparable to that in the wild type, but severely disrupted in the double null, suggests a role for lumican that is crucial in the absence of Fibromodulin. The eyes of Lum(-/-)Fmod(-/-) mice show certain features of high myopia: increased axial length, thin sclera, and retinal detachment. Mutations or altered expression of these proteoglycans may contribute to myopia in humans.
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ocular and scleral alterations in gene targeted lumican Fibromodulin double null mice
Investigative Ophthalmology & Visual Science, 2003Co-Authors: Shukti Chakravarti, L Roberts, Inna Chervoneva, Ake Oldberg, J. Paul, David E BirkAbstract:PURPOSE: To elucidate the role of leucine-rich proteoglycans lumican and Fibromodulin in the sclera. METHODS: Lumican- and Fibromodulin-null heterozygous mice were intercrossed to obtain wild-type (Lum(+/+)Fmod(+/+)), lumican-null (Lum(-/-)Fmod(+/+)), Fibromodulin-null (Lum(+/+)Fmod(-/-)), and double-null (Lum(-/-)Fmod(-/-)) littermates. Axial length was measured on enucleated whole eyes, and ocular structural changes were examined by histology. The morphology of collagen fibrils in the sclera was examined by transmission electron microscopy (TEM). RESULTS: Compared with the ocular axial length in wild type mice, the axial length was increased by 10% in Lum(-/-)Fmod(-/-) (P = 0.02) mice. Retinal detachment was frequent in the double-null and rare in the lumican-null animals. Compared with the wild-type sclera, the sclera in all null mutants was significantly thinner with fewer lamellae (P < 0.05). The double-null sclera contained abnormally large-diameter (120-160 nm) and small-diameter (30-60 nm) collagen fibrils, whereas the Fibromodulin-null sclera was enriched for the small-diameter fibrils. The collagen fibril diameter distribution in the lumican-null sclera was similar to that of the wild-type. CONCLUSIONS: An increase in small-diameter fibrils in the Fibromodulin-null sclera suggests a key role for Fibromodulin in the maturation and assembly of scleral collagen fibrils. That fibril diameter distribution in the lumican-null sclera was comparable to that in the wild type, but severely disrupted in the double null, suggests a role for lumican that is crucial in the absence of Fibromodulin. The eyes of Lum(-/-)Fmod(-/-) mice show certain features of high myopia: increased axial length, thin sclera, and retinal detachment. Mutations or altered expression of these proteoglycans may contribute to myopia in humans. (Less)
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a syndrome of joint laxity and impaired tendon integrity in lumican and Fibromodulin deficient mice
Journal of Biological Chemistry, 2002Co-Authors: Karl J Jepsen, Yoichi Ezura, L Roberts, Ake Oldberg, J. Paul, David E Birk, Feng Wu, Jason H Peragallo, Shukti ChakravartiAbstract:Lumican and Fibromodulin regulate the assembly of collagens into higher order fibrils in connective tissues. Here, we show that mice deficient in both of these proteoglycans manifest several clinical features of Ehlers-Danlos syndrome. The Lum(-/-)Fmod(-/-) mice are smaller than their wild type littermates and display gait abnormality, joint laxity, and age-dependent osteoarthritis. Misaligned knee patella, severe knee dysmorphogenesis, and extreme tendon weakness are the likely causes for joint laxity in the double-nulls. Fibromodulin deficiency alone leads to significant reduction in tendon stiffness in the Lum(+/+)Fmod(-/-) mice, with further loss in stiffness in a Lum gene dose-dependent way. At the protein level, we show marked increase of lumican in Fmod(-/-) tendons, which may partially rescue the tendon phenotype in this genotype. These results establish Fibromodulin as a key regulator and lumican as a modulator of tendon strength. A disproportionate increase in small diameter immature collagen fibrils and a lack of progression to mature, large diameter fibrils in the Fmod(-/-) background may constitute the underlying cause of tendon weakness and suggest that Fibromodulin aids fibril maturation. This study demonstrates that the collagen fibril-modifying proteoglycans, lumican and Fibromodulin, are candidate genes and key players in the pathogenesis of certain types of Ehlers-Danlos syndrome and other connective tissue disorders.
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differential expression of lumican and Fibromodulin regulate collagen fibrillogenesis in developing mouse tendons
Journal of Cell Biology, 2000Co-Authors: Yoichi Ezura, Inna Chervoneva, Ake Oldberg, Shukti Chakravarti, David E BirkAbstract:Collagen fibrillogenesis is finely regulated during development of tissue-specific extracellular matrices. The role(s) of a leucine-rich repeat protein subfamily in the regulation of fibrillogenesis during tendon development were defined. Lumican-, Fibromodulin-, and double-deficient mice demonstrated disruptions in fibrillogenesis. With development, the amount of lumican decreases to barely detectable levels while Fibromodulin increases significantly, and these changing patterns may regulate this process. Electron microscopic analysis demonstrated structural abnormalities in the fibrils and alterations in the progression through different assembly steps. In lumican-deficient tendons, alterations were observed early and the mature tendon was nearly normal. Fibromodulin-deficient tendons were comparable with the lumican-null in early developmental periods and acquired a severe phenotype by maturation. The double-deficient mice had a phenotype that was additive early and comparable with the Fibromodulin-deficient mice at maturation. Therefore, lumican and Fibromodulin both influence initial assembly of intermediates and the entry into fibril growth, while Fibromodulin facilitates the progression through growth steps leading to mature fibrils. The observed increased ratio of Fibromodulin to lumican and a competition for the same binding site could mediate these transitions. These studies indicate that lumican and Fibromodulin have different developmental stage and leucine-rich repeat protein specific functions in the regulation of fibrillogenesis.
Dick Heinegard - One of the best experts on this subject based on the ideXlab platform.
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nc4 domain of cartilage specific collagen ix inhibits complement directly due to attenuation of membrane attack formation and indirectly through binding and enhancing activity of complement inhibitors c4b binding protein and factor h
Journal of Biological Chemistry, 2011Co-Authors: Nikolina Kalchishkova, Dick Heinegard, Camilla Melin Furst, Anna M BlomAbstract:Collagen IX containing the N-terminal noncollagenous domain 4 (NC4) is unique to cartilage and a member of the family of fibril-associated collagens with both collagenous and noncollagenous domains. Collagen IX is located at the surface of fibrils formed by collagen II and a minor proportion of collagen XI, playing roles in tissue stability and integrity. The NC4 domain projects out from the fibril surface and provides sites for interaction with other matrix components such as cartilage oligomeric matrix protein, matrilins, Fibromodulin, and osteoadherin. Fragmentation of collagen IX and loss of the NC4 domain are early events in cartilage degradation in joint diseases that precedes major damage of collagen II fibrils. Our results demonstrate that NC4 can function as a novel inhibitor of the complement system able to bind C4, C3, and C9 and to directly inhibit C9 polymerization and assembly of the lytic membrane attack complex. NC4 also binds the complement inhibitors C4b-binding protein and factor H and enhances their cofactor activity in degradation of activated complement components C4b and C3b. NC4 interactions with Fibromodulin and osteoadherin inhibited binding to C1q and complement activation by these proteins. Taken together, our results suggest that collagen IX and its interactions with matrix components are important parts of a machinery that protects the cartilage from complement activation and chronic inflammation seen in diseases like rheumatoid arthritis.
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the tyrosine sulfate rich domains of the lrr proteins Fibromodulin and osteoadherin bind motifs of basic clusters in a variety of heparin binding proteins including bioactive factors
Journal of Biological Chemistry, 2009Co-Authors: Viveka Tillgren, Patrik Onnerfjord, Dick HeinegardAbstract:The small leucine-rich repeat proteins, Fibromodulin and osteoadherin, have N-terminal extensions with a variable number of O-sulfated tyrosine residues. This modification combined with a number of aspartic and glutamic acid residues results in a highly negatively charged domain of less than 30 amino acids. We hypothesized that this domain shares functional properties with heparin regarding binding to proteins and polypeptides containing clusters of basic amino acids. Two other family members, PRELP and chondroadherin, have distinctly different clusters of basic amino acids in their N and C termini, respectively, and PRELP is known to bind to heparin via this domain. Another heparin-binding protein is the cytokine Oncostatin M, with a different cluster of basic amino acids in its C terminus. We used polypeptides representing these basic domains in solid phase assays and demonstrate interactions with the negatively charged N-terminal domain of Fibromodulin and full-length osteoadherin. The tyrosine sulfate domains also bound heparin-binding proteins such as basic fibroblast growth factor-2, thrombospondin I, MMP13, the NC4 domain of collagen IX, and interleukin-10. Fibronectin with large heparin-binding domains did not bind, neither did CILP containing a heparin-binding thrombospondin type I motif without clustered basic amino acids. Affinity depends on the number and position of the sulfated tyrosine residues shown by different binding properties of 10-kDa fragments subfractionated by ion-exchange chromatography. These interactions may sequester growth factors, cytokines, and matrix metalloproteinases in the extracellular matrix as well as contribute to its organization.
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short leucine rich glycoproteins of the extracellular matrix display diverse patterns of complement interaction and activation
Molecular Immunology, 2009Co-Authors: Andreas P Sjoberg, Dick Heinegard, Matthias Morgelin, Gavin Manderson, Anthony J Day, Anna M BlomAbstract:The extracellular matrix consists of structural macromolecules and other proteins with regulatory functions. An important family of the latter class of molecules found in most tissues is the small leucine-rich repeat proteins (SLRPs). We have previously shown that the SLRP Fibromodulin binds directly to C1q and activates the classical pathway of complement. In the present study we further examine the interactions between SLRPs and complement. Osteoadherin, like Fibromodulin, binds C1q and activates the classical pathway strongly while moderate activation is seen in the terminal pathway. This can be explained by the interaction of Fibromodulin and osteoadherin with factor H, a major soluble inhibitor of complement. Also, chondroadherin was found to bind C1q and activate complement, albeit to a lesser extent. Chondroadherin also binds factor H. We confirm published data showing that biglycan and decorin bind C1q but do not activate complement. In this study a similar pattern is seen for lumican although its affinity for C1q is lower than for biglycan and decorin. Furthermore, using electron microscopy and radiolabeled SLRPs, we demonstrate two different classes of SLRP binding sites on C1q, to head and stalk respectively, where only binding to the head appears to be activating. We propose a role for SLRPs in the regulation of complement activation in diseases involving the extracellular matrix, particularly those characterized by chronic inflammation such as rheumatoid arthritis, atherosclerosis, osteoarthritis and chronic obstructive lung disease.
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the factor h variant associated with age related macular degeneration his 384 and the non disease associated form bind differentially to c reactive protein Fibromodulin dna and necrotic cells
Journal of Biological Chemistry, 2007Co-Authors: Andreas P Sjoberg, Dick Heinegard, Anthony J Day, Leendert A Trouw, Simon J Clark, Jonatan Sjolander, Robert B Sim, Anna M BlomAbstract:Recently, a polymorphism in the complement regulator factor H (FH) gene has been associated with age-related macular degeneration. When histidine instead of tyrosine is present at position 384 in the seventh complement control protein (CCP) domain of FH, the risk for age-related macular degeneration is increased. It was recently shown that these allotypic variants of FH, in the context of a recombinant construct corresponding to CCPs 6-8, recognize polyanionic structures differently, which may lead to altered regulation of the alternative pathway of complement. We show now that His-384, corresponding to the risk allele, binds C-reactive protein (CRP) poorly compared with the Tyr-384 form. We also found that C1q and phosphorylcholine do not compete with FH for binding to C-reactive protein. The interaction with extracellular matrix protein Fibromodulin, which we now show to be mediated, at least in part, by CCP6-8 of FH, occurs via the polypeptide of Fibromodulin and not through its glycosaminoglycan modifications. The Tyr-384 variant of FH bound Fibromodulin better than the His-384 form. Furthermore, we find that CCP6-8 is able to interact with DNA and necrotic cells, but in contrast the His-384 allotype binds these ligands more strongly than the Tyr-384 variant. The variations in binding affinity of the two alleles indicate that complement activation and local inflammation in response to different targets will differ between His/His and Tyr/Tyr homozygotes.
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the extracellular matrix and inflammation Fibromodulin activates the classical pathway of complement by directly binding c1q
Journal of Biological Chemistry, 2005Co-Authors: Andreas P Sjoberg, Patrik Onnerfjord, Dick Heinegard, Matthias Morgelin, Anna M BlomAbstract:Components that propagate inflammation in joint disease may be derived from cartilage since the inflammation resolves after joint replacement. We found that the cartilage component Fibromodulin has the ability to activate an inflammatory cascade, i.e. complement. Fibromodulin and immunoglobulins cause comparable deposition of C1q, C4b, and C3b from human serum. Using C1q and factor B-deficient sera in combination with varying contents of metal ions, we established that Fibromodulin activates both the classical and the alternative pathways of complement. Further studies revealed that Fibromodulin binds directly to the globular heads of C1q, leading to activation of C1. However, deposition of the membrane attack complex and C5a release were lower in the presence of Fibromodulin as compared with IgG. This can be explained by the fact that Fibromodulin also binds complement inhibitor factor H. Factor H and C1q bind to non-overlapping sites on Fibromodulin, but none of the interactions is mediated by the negatively charged keratan sulfate substituents of Fibromodulin. C1q but not factor H binds to an N-terminal fragment of Fibromodulin previously implicated to be affected in cartilage stimulated with the inflammatory cytokine interleukin 1. Taken together our observations indicate Fibromodulin as one factor involved in the sustained inflammation of the joint.
Shukti Chakravarti - One of the best experts on this subject based on the ideXlab platform.
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Ultrasound and microbubble-assisted gene delivery in Achilles tendons: long lasting gene expression and restoration of Fibromodulin KO phenotype.
Journal of Controlled Release, 2011Co-Authors: Anthony Delalande, Shukti Chakravarti, Patrick Midoux, Ayache Bouakaz, Gilles Renault, Flore Tabareau, Spiros Kotopoulis, Brigitte Arbeille, Rustem Uzbekov, Michiel PostemaAbstract:The aim of this study is to deliver genes in Achilles tendons using ultrasound and microbubbles. The rationale is to combine ultrasound-assisted delivery and the stimulation of protein expression induced by US. We found that mice tendons injected with 10 μg of plasmid encoding luciferase gene in the presence of 5×10⁵ BR14 microbubbles, exposed to US at 1 MHz, 200 kPa, 40% duty cycle for 10 min were efficiently transfected without toxicity. The rate of luciferase expression was 100-fold higher than that obtained when plasmid alone was injected. Remarkably, the luciferase transgene was stably expressed for up to 108 days. DNA extracted from these sonoporated tendons was efficient in transforming competent E. coli bacteria, indicating that persistent intact pDNA was responsible for this long lasting gene expression. We used this approach to restore expression of the Fibromodulin gene in Fibromodulin KO mice. A significant Fibromodulin expression was detected by quantitative PCR one week post-injection. Interestingly, ultrastructural analysis of these tendons revealed that collagen fibrils diameter distribution and circularity were similar to that of wild type mice. Our results suggest that this gene delivery method is promising for clinical applications aimed at modulating healing or restoring a degenerative tendon while offering great promise for gene therapy due its safety compared to viral methods.
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Fibromodulin regulates collagen fibrillogenesis during peripheral corneal development
Developmental Dynamics, 2010Co-Authors: Shoujun Chen, Ake Oldberg, Shukti Chakravarti, David E BirkAbstract:Fibromodulin regulates collagen fibrillogenesis, but its existence/role(s) in the cornea is controversial. We hypothesize that Fibromodulin regulates fibrillogenesis during postnatal development of the anterior eye. Fibromodulin is weakly expressed in the limbus at post-natal day (P) 4, increases and extends into the central cornea at P14, becomes restricted to the limbus at P30, and decreases at P60. This differential spatial and temporal expression of Fibromodulin is coordinated with emmetropization; the developmental increase in axial length and globe size. Genetic analysis demonstrated that Fibromodulin regulates fibrillogenesis in a region-specific manner. At the limbus, Fibromodulin is dominant in regulating fibril growth during postnatal development. In the posterior peripheral cornea, cooperative interactions of Fibromodulin and lumican regulate fibrillogenesis. These data indicate that Fibromodulin plays important roles in the regulation of region-specific fibrillogenesis required for the integration of the corneal and scleral matrices and sulcus development required for establishment of the visual axis.
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ocular and scleral alterations in gene targeted lumican Fibromodulin double null mice
Investigative Ophthalmology & Visual Science, 2003Co-Authors: Shukti Chakravarti, L Roberts, Inna Chervoneva, Ake Oldberg, J. Paul, David E BirkAbstract:PURPOSE: To elucidate the role of leucine-rich proteoglycans lumican and Fibromodulin in the sclera. METHODS: Lumican- and Fibromodulin-null heterozygous mice were intercrossed to obtain wild-type (Lum(+/+)Fmod(+/+)), lumican-null (Lum(-/-)Fmod(+/+)), Fibromodulin-null (Lum(+/+)Fmod(-/-)), and double-null (Lum(-/-)Fmod(-/-)) littermates. Axial length was measured on enucleated whole eyes, and ocular structural changes were examined by histology. The morphology of collagen fibrils in the sclera was examined by transmission electron microscopy (TEM). RESULTS: Compared with the ocular axial length in wild type mice, the axial length was increased by 10% in Lum(-/-)Fmod(-/-) (P = 0.02) mice. Retinal detachment was frequent in the double-null and rare in the lumican-null animals. Compared with the wild-type sclera, the sclera in all null mutants was significantly thinner with fewer lamellae (P < 0.05). The double-null sclera contained abnormally large-diameter (120-160 nm) and small-diameter (30-60 nm) collagen fibrils, whereas the Fibromodulin-null sclera was enriched for the small-diameter fibrils. The collagen fibril diameter distribution in the lumican-null sclera was similar to that of the wild-type. CONCLUSIONS: An increase in small-diameter fibrils in the Fibromodulin-null sclera suggests a key role for Fibromodulin in the maturation and assembly of scleral collagen fibrils. That fibril diameter distribution in the lumican-null sclera was comparable to that in the wild type, but severely disrupted in the double null, suggests a role for lumican that is crucial in the absence of Fibromodulin. The eyes of Lum(-/-)Fmod(-/-) mice show certain features of high myopia: increased axial length, thin sclera, and retinal detachment. Mutations or altered expression of these proteoglycans may contribute to myopia in humans.
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ocular and scleral alterations in gene targeted lumican Fibromodulin double null mice
Investigative Ophthalmology & Visual Science, 2003Co-Authors: Shukti Chakravarti, L Roberts, Inna Chervoneva, Ake Oldberg, J. Paul, David E BirkAbstract:PURPOSE: To elucidate the role of leucine-rich proteoglycans lumican and Fibromodulin in the sclera. METHODS: Lumican- and Fibromodulin-null heterozygous mice were intercrossed to obtain wild-type (Lum(+/+)Fmod(+/+)), lumican-null (Lum(-/-)Fmod(+/+)), Fibromodulin-null (Lum(+/+)Fmod(-/-)), and double-null (Lum(-/-)Fmod(-/-)) littermates. Axial length was measured on enucleated whole eyes, and ocular structural changes were examined by histology. The morphology of collagen fibrils in the sclera was examined by transmission electron microscopy (TEM). RESULTS: Compared with the ocular axial length in wild type mice, the axial length was increased by 10% in Lum(-/-)Fmod(-/-) (P = 0.02) mice. Retinal detachment was frequent in the double-null and rare in the lumican-null animals. Compared with the wild-type sclera, the sclera in all null mutants was significantly thinner with fewer lamellae (P < 0.05). The double-null sclera contained abnormally large-diameter (120-160 nm) and small-diameter (30-60 nm) collagen fibrils, whereas the Fibromodulin-null sclera was enriched for the small-diameter fibrils. The collagen fibril diameter distribution in the lumican-null sclera was similar to that of the wild-type. CONCLUSIONS: An increase in small-diameter fibrils in the Fibromodulin-null sclera suggests a key role for Fibromodulin in the maturation and assembly of scleral collagen fibrils. That fibril diameter distribution in the lumican-null sclera was comparable to that in the wild type, but severely disrupted in the double null, suggests a role for lumican that is crucial in the absence of Fibromodulin. The eyes of Lum(-/-)Fmod(-/-) mice show certain features of high myopia: increased axial length, thin sclera, and retinal detachment. Mutations or altered expression of these proteoglycans may contribute to myopia in humans. (Less)
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a syndrome of joint laxity and impaired tendon integrity in lumican and Fibromodulin deficient mice
Journal of Biological Chemistry, 2002Co-Authors: Karl J Jepsen, Yoichi Ezura, L Roberts, Ake Oldberg, J. Paul, David E Birk, Feng Wu, Jason H Peragallo, Shukti ChakravartiAbstract:Lumican and Fibromodulin regulate the assembly of collagens into higher order fibrils in connective tissues. Here, we show that mice deficient in both of these proteoglycans manifest several clinical features of Ehlers-Danlos syndrome. The Lum(-/-)Fmod(-/-) mice are smaller than their wild type littermates and display gait abnormality, joint laxity, and age-dependent osteoarthritis. Misaligned knee patella, severe knee dysmorphogenesis, and extreme tendon weakness are the likely causes for joint laxity in the double-nulls. Fibromodulin deficiency alone leads to significant reduction in tendon stiffness in the Lum(+/+)Fmod(-/-) mice, with further loss in stiffness in a Lum gene dose-dependent way. At the protein level, we show marked increase of lumican in Fmod(-/-) tendons, which may partially rescue the tendon phenotype in this genotype. These results establish Fibromodulin as a key regulator and lumican as a modulator of tendon strength. A disproportionate increase in small diameter immature collagen fibrils and a lack of progression to mature, large diameter fibrils in the Fmod(-/-) background may constitute the underlying cause of tendon weakness and suggest that Fibromodulin aids fibril maturation. This study demonstrates that the collagen fibril-modifying proteoglycans, lumican and Fibromodulin, are candidate genes and key players in the pathogenesis of certain types of Ehlers-Danlos syndrome and other connective tissue disorders.