BACKGROUND: The mechanism by which mutant cartilage oligomeric matrix protein (COMP) induces a pseudoachondroplasia phenotype remains unknown, and the reason why a mutation of a minor protein of the growth plate cartilage causes total disruption of endochondral bone formation has not yet been determined. The current study was performed to investigate the effects of mutated COMP on the synthesis of the cartilage-specific major matrix proteins of Swarm rat chondrosarcoma chondrocytes. METHODS: The Swarm rat chondrosarcoma chondrocytes transfected with a chimeric construct, which consisted of a mutant gene of human COMP and an amino acid FLAG tag sequence, were cultured in agarose gel. Formation of extracellular proteoglycan and type-II collagen by the cells was evaluated by immunohistochemical staining and measuring the (35)S-sulfate incorporation. RESULTS: No difference was observed for the detection of type-II collagen among the cell lines expressing mutant COMP and the control cell lines. Histochemical staining of sulfated proteoglycans with safranin-O showed that lesser amounts of proteoglycans were incorporated into the extracellular matrix of the chondrocytes transfected with the mutant gene. (35)S-sulfate incorporation into the cell/matrix fractions demonstrated markedly lower radiolabel incorporation, as compared to that of the control cells. CONCLUSIONS: Mutation of COMP has an important impact on the processing of proteoglycans, rather than type-II collagen, in the three-dimensional culture of Swarm rat chondrosarcoma chondrocytes.
Aggrecans/analysis/*biosynthesis ; Animals ; Cells, Cultured ; Chondrocytes/*metabolism ; Chondrosarcoma/metabolism ; Collagen Type II/*biosynthesis ; Extracellular Matrix/*metabolism ; Extracellular Matrix Proteins/*genetics ; Glycoproteins/*genetics ; Humans ; Mutation ; Rats ; Transfection

Articular cartilage is a connective tissue consisting of a specialized extracellular matrix (ECM) that dominates the bulk of its wet and dry weight. Type II collagen and aggrecan are the main ECM proteins in cartilage. However, little attention has been paid to less abundant molecular components, especially minor collagens, including type IV, VI, IX, X, XI, XII, XIII, and XIV, etc. Although accounting for only a small fraction of the mature matrix, these minor collagens not only play essential structural roles in the mechanical properties, organization, and shape of articular cartilage, but also fulfil specific biological functions. Genetic studies of these minor collagens have revealed that they are associated with multiple connective tissue diseases, especially degenerative joint disease. The progressive destruction of cartilage involves the degradation of matrix constituents including these minor collagens. The generation and release of fragmented molecules could generate novel biochemical markers with the capacity to monitor disease progression, facilitate drug development and add to the existing toolbox for in vitro studies, preclinical research and clinical trials.
Aggrecans ; chemistry ; genetics ; metabolism ; Animals ; Biomarkers ; metabolism ; Cartilage, Articular ; chemistry ; metabolism ; pathology ; Collagen ; chemistry ; classification ; genetics ; metabolism ; Extracellular Matrix Proteins ; chemistry ; genetics ; metabolism ; Gene Expression ; Humans ; Osteoarthritis ; diagnosis ; genetics ; metabolism ; pathology ; Protein Isoforms ; chemistry ; classification ; genetics ; metabolism

The ADAMTS (a disintegrin and metalloproteinase with thrombospondin motifs) family consists of 19 proteases. These enzymes are known to play important roles in development, angiogenesis and coagulation; dysregulation and mutation of these enzymes have been implicated in many disease processes, such as inflammation, cancer, arthritis and atherosclerosis. This review briefly summarizes the structural organization and functional roles of ADAMTSs in normal and pathological conditions, focusing on members that are known to be involved in the degradation of extracellular matrix and loss of cartilage in arthritis, including the aggrecanases (ADAMTS-4 and ADAMTS-5), ADAMTS-7 and ADAMTS-12, the latter two are associated with cartilage oligomeric matrix protein (COMP), a component of the cartilage extracellular matrix (ECM). We will discuss the expression pattern and the regulation of these metalloproteinases at multiple levels, including their interaction with substrates, induction by pro-inflammatory cytokines, protein processing, inhibition (e.g., TIMP-3, alpha-2-macroglobulin, GEP), and activation (e.g., syndecan-4, PACE-4).
ADAM Proteins ; antagonists & inhibitors ; chemistry ; genetics ; physiology ; Aggrecans ; metabolism ; Alternative Splicing ; Arthritis ; enzymology ; genetics ; Cartilage ; enzymology ; Endopeptidases ; genetics ; physiology ; Extracellular Matrix ; enzymology ; Humans ; Protein Structure, Tertiary

OBJECTIVETo study the effect of RNA interference (RNAi)-mediated aggrecanase-1 gene silencing on extracellular matrix metabolism of cultured rat costochondral chondrocytes.

METHODSRat costochondral chondrocyte monolayers were obtained by microdissection and digestion. The growth and morphological changes of the chondrocytes were observed after RNAi of aggrecanase-1 gene. The mRNA expression of aggrecanase-1 was detected by RT-PCR method, and aggrecan content was determined by Western blotting.

RESULTSThe specific inhibition of aggrecanase-1 by RNAi produced no adverse effect on the morphology and growth of the chondrocytes. The mRNA of aggrecanase-1 decreased and aggrecan content increased significantly after transfection of the chondrocytes.

CONCLUSIONInhibition of aggrecanase-1 decreases aggrecan degradation in cultured rat chondrocytes. RNAi technique can be a useful means for studying extracellular matrix metabolism in the cartilage.

ADAM Proteins ; genetics ; metabolism ; ADAMTS4 Protein ; Aggrecans ; metabolism ; Animals ; Cells, Cultured ; Chondrocytes ; cytology ; metabolism ; Extracellular Matrix ; metabolism ; Female ; Procollagen N-Endopeptidase ; genetics ; metabolism ; RNA Interference ; RNA, Messenger ; genetics ; Rats ; Rats, Sprague-Dawley ; Transfection

OBJECTIVETo explore the isolation, in vitro culture and chondrogenic differentiation of goat bone marrow mesenchymal stem cells (BMSCs).

METHODSBone marrow was harvested from a 10-month-old Chinese goat for adherent culture of the BMSCs in vitro. Flow cytometry was performed to detect the cell surface markers of the BMSCs of the fourth generation. The induction medium (containing 10% fetal bovine serum, high-glucose DMEM, 6.25 microg/ml insulin, 6.25 microg/ml transferrin, 50 microg/ml vitamin C, 100 nmol/L DXM and 10 ng/ml transforming growth factor-beta1) was then applied for chondrogenic differentiation. Cytochemical staining, RT-PCR and Western blotting were performed to detect the expressions of type II collagen and aggrecan in the cells at the time points of 0, 1, 2 and 4 weeks.

RESULTSThe goat BMSCs grow well in vitro with a high purity in the fourth generation. The expression of chondrocyte phenotypes were observed at 1, 2 and 4 weeks, which became more obvious as the culture prolonged. The mRNA and protein expression of type II collagen and aggrecan in the BMSCs increased obvious after the induction and had reached a satisfactory level by 2 weeks.

CONCLUSIONGoat BMSCs have the potential to differentiate into chondrocytes in vitro, and the results of this study provide the experimental basis for application of goat BMSCs in bone and cartilage tissue engineering in vivo.

Aggrecans ; genetics ; metabolism ; Animals ; Bone Marrow Cells ; cytology ; Cell Culture Techniques ; Cell Differentiation ; Cell Separation ; Cells, Cultured ; Chondrocytes ; cytology ; Collagen Type II ; genetics ; metabolism ; Goats ; Mesenchymal Stromal Cells ; cytology ; RNA, Messenger ; genetics ; metabolism

OBJECTIVETo investigate the role of GATA4 gene in the endocardial cushions development.

METHODSTarget gene eukaryote expression vectors were constructed by pcDNA3.1(-) vector plasmid, and were identified by DNA sequence analysis. Recombinant plasmids were transfected into Hela cells with lipofectamine 2000, meanwhile Hela cells transfected with empty vector or those without transfection served as transfection control group and blank control group, respectively. Real-time PCR and Western blot were performed to detect the relative expression of mRNA and protein of transcription factors GATA4, Sox9, Scleraxis and ECM proteins Aggrecan, Tenascin in each group.

RESULTSThe relative mRNA expression of GATA4 in experimental group was significantly higher than in transfection control group and blank control group. GATA4 mRNA expression in Hela(GATA4), Hela(H436Y), Hela(Null) and Hela group was 310.83 ± 2.39, 146.35 ± 1.74, 0.94 ± 0.32, 1.00 ± 0.28, respectively (F = 72.508, P < 0.05). Western blot results were consistent with the results obtained by qRT-PCR. The relative mRNA and protein expressions of Sox9, Scleraxis, Aggrecan and Tenascin in both experimental groups were significantly higher than that in transfection control group and blank control group (P < 0.05), and above gene expressions were significantly downregulated in GATA4(H436Y) group, while they were similar between transfection control group and blank control group (all P > 0.05).

CONCLUSIONSGATA4 H436Y mutation reduces it's transcriptional activation, which might serve as a theoretical framework to demonstrate the roles of GATA4 gene in endocardial cushion development.

Aggrecans ; metabolism ; Basic Helix-Loop-Helix Transcription Factors ; metabolism ; Down-Regulation ; Endocardial Cushions ; embryology ; GATA4 Transcription Factor ; genetics ; metabolism ; Gene Expression ; Genetic Vectors ; HeLa Cells ; Humans ; RNA, Messenger ; SOX9 Transcription Factor ; metabolism ; Tenascin ; metabolism ; Transfection

OBJECTIVETo evaluate the effect of interleukin-6 (IL-6) on the biological behaviors of the chondrocytes in the cartilage endplate of rabbits.

METHODSChondrocytes isolated from the cartilage endplate of New Zealand rabbits, verified for their biological characteristics by such means as toluidine blue staining for type II collagen, were treated with IL-6 at different concentrations. The proliferation of the chondrocytes was evaluated by MTT assay at different time points following the treatment, the cell cycle changes were determined by flow cytometry and the changes of aggrecan and type II collagen mRNAs detected by RT-PCR.

RESULTSAt the concentrations of 10, 50 and 100 ng/ml, IL-6 did not obviously affect the rate of chondrocyte proliferation. IL-6 at 50 ng/ml resulted in no obvious changes of the cell cycle of the chondrocytes, but significantly decreased the expression of collagen IIa mRNA.

CONCLUSIONIL-6 has no effect on the proliferation and cell cycle of the chondrocytes, but at higher concentrations, it inhibits matrix synthesis of the chondrocytes to promote intervertebral disc degeneration.

Aggrecans ; genetics ; Animals ; Cartilage ; cytology ; Cell Cycle ; drug effects ; Cell Proliferation ; drug effects ; Chondrocytes ; cytology ; drug effects ; metabolism ; Collagen Type II ; genetics ; Female ; Gene Expression Regulation ; drug effects ; Interleukin-6 ; pharmacology ; Male ; RNA, Messenger ; genetics ; metabolism ; Rabbits

Larger animal models, such as porcine, have been validated as appropriate models of the human disc with respect to biomechanics and biochemistry. They are advantageous for research as the models are relatively straightforward to prepare and easily obtainable for research to perform surgical techniques. The intention of this study was to quantitatively analyze gene expression for collagen and proteoglycan components of the extracellular matrix and for collagenase (MMP-1) in porcine discs of varying ages (Newborn; 2-3weeks, Mature; 6-9 month, Older; 2-3 years). In this study, we observed that the cell number and GAG (glycosaminoglycan) formation dramatically decreased with aging. Also, gene expression in the annulus fibrosus (AF) and nucleus pulposus (NP) cells changed with aging. The level of MMP-1 mRNA increased with age and both type I, II collagens decreased with age. The level of aggrecan mRNA was highest in the mature group and decreased significantly with aging. In the mature group, MMP-1 expression was minimal compared to the newborn group. In AF cells, type II collagen was expressed at a high level in the mature group with a higher level of aggrecan, when aged NP showed a decrease in type II collagen. The model of IVD degeneration in the porcine disc shows many changes in gene expression with age that have been previously documented for human and may serve as a model for studying changes in IVD metabolism with age. We concluded that the porcine model is excellent to test hypotheses related to disc degeneration while permitting time-course study in biologically active systems.
Age Factors ; Aggrecans/genetics/metabolism ; Aging/genetics/*metabolism ; Animals ; Animals, Newborn ; Collagen Type I/genetics/metabolism ; Collagen Type II/genetics/metabolism ; Glycosaminoglycans/genetics/metabolism ; Humans ; Intervertebral Disk Degeneration/genetics/*metabolism ; Matrix Metalloproteinase 1/genetics/*metabolism ; *Models, Animal ; Reverse Transcriptase Polymerase Chain Reaction ; Spinal Cord/*metabolism/pathology ; Swine

This study was done to evaluate whether injections of resveratrol, a natural compound found in the skin of grapes, had anabolic effects on degenerated intervertebral discs in a rabbit model. Two non-continuous lumbar discs were punctured in rabbits to induce disc degeneration. Four weeks and 6 weeks after puncture, the rabbits were treated by injections with dimethylsulfoxide (DMSO) or resveratrol. At 4, 8, and 16 weeks after initial injection, rabbits were sacrificed and the spine was extracted for magnetic resonance image (MRI), mRNA expression, and histological staining. Resveratrol treatment resulted in stronger signal intensity in T2-weighted images. MRI grade showed significantly lower in the resveratrol group than the DMSO group (P = 0.039). In the resveratrol group, aggrecan gene expression was significantly increased than that in the DMSO group at 16 weeks after injection (P = 0.027). MMP-13 mRNA levels in the resveratrol group were significantly decreased than those in the DMSO group at 8 and 16 weeks (P = 0.006 and P = 0.048, respectively). In hematoxylin and eosin stain, resveratrol-treated discs showed the features of regeneration. Histologic grade revealed improvement in resveratrol-treated discs, compared with DMSO-treated discs (P = 0.024). These anabolic effects on degenerated discs indicate that resveratrol is a promising candidate for treatment of degenerative disc disease.
Aggrecans/genetics/metabolism ; Anabolic Agents/*administration & dosage ; Animals ; Disease Models, Animal ; Drug Administration Schedule ; Intervertebral Disc Degeneration/*drug therapy/pathology ; Magnetic Resonance Imaging ; Matrix Metalloproteinase 13/genetics/metabolism ; RNA, Messenger/metabolism ; Rabbits ; Spine/radiography ; Stilbenes/*administration & dosage

OBJECTIVETo study the inhibitory effect of T-2 toxin on the expression of aggrecan and collagen II in chondrocytes and the protection of selenium against this effect.

METHODSHuman chondrocytes cultured in vitro were treated with T-2 toxin at different concentrations for varied time periods (1-5 days), and the cell viability was measured by MTT assay. Aggrecan expression was detected by toluidine blue staining and collagen II expression by immunostaining using monoclonal antibody of collagen. Aggrecan and collagen II mRNA expressions were measured by semiquantitative RT-PCR.

RESULTST-2 toxin dose- and time-dependently affected chondrocyte viability within the concentration range of 0.001-2 mg/L, the prolonged treatment time further enhanced the dose dependence of the inhibitory effect. T-2 toxin lowered aggrecan and collagen II synthesis in the chondrocytes and reduced their mRNA expressions. Selenium could partly attenuate the inhibitory effects of T-2 toxin on aggrecan mRNA expression, but showed no such effect against T-2-induced collagen II expression.

CONCLUSIONT-2 toxin can obviously inhibit aggrecan and collagen II synthesis in human chondrocytes, and selenium can partly antagonize the inhibitory effects of T-2 toxin on aggrecan.

Aggrecans ; biosynthesis ; genetics ; Cells, Cultured ; Chondrocytes ; cytology ; metabolism ; Collagen Type II ; biosynthesis ; genetics ; Dose-Response Relationship, Drug ; Fetus ; Humans ; Protective Agents ; pharmacology ; RNA, Messenger ; biosynthesis ; genetics ; Selenium ; pharmacology ; T-2 Toxin ; toxicity