Distinct Phases of Coordinated Early and Late Gene Expression in Growth Plate Chondrocytes in Relationship to Cell Proliferation, Matrix Assembly, Remodeling, and Cell Differentiation

Shriners Hospitals for Children, Tampa, Florida, United States
Journal of Bone and Mineral Research (Impact Factor: 6.83). 06/2003; 18(5):844-51. DOI: 10.1359/jbmr.2003.18.5.844
Source: PubMed


Although much has been learned about growth plate development and chondrocyte gene expression during cellular maturation and matrix remodeling in the mouse, there has been a limited study of the interrelationships of gene expression between proteinases, growth factors, and other regulatory molecules in the mouse and in other species. Here we use RT-PCR of sequential transverse sections to examine the expression profiles of genes involved in chondrocyte growth, differentiation, matrix assembly, remodeling, and mineralization in the bovine proximal tibial growth plate. Specifically, we studied the expression of genes encoding COL2A1 and COL10A1, the latter a marker of cellular hypertrophy, the matrix metalloproteinases (MMP), MMP-13 and MMP-9, as well as the transcriptional factors, Sox9 and Cbfa1, the growth factors basic fibroblast growth factor (bFGF), parathyroid hormone-related peptide (PTHrP), transforming growth factor (TGF)beta1, and beta2, Indian hedgehog (Ihh), and the matrix protein osteocalcin. These were analyzed in relationship to cell division defined by cyclin B2 expression. Two peaks of gene expression activity were observed. One was transient, limited, and located immediately before and at the onset of cyclin B2 expression in the early proliferative zone. The other was generally much more pronounced and was located in the early hypertrophic zone. The upregulation of expression of COL2A1, its transcriptional activator Sox9, osteocalcin, MMP-13, and TGFbeta2 was observed immediately before and at the onset of cyclin B2 expression and also in the hypertrophic zones. The upregulation of COL10A1, Cbfa1, MMP-9, TGFbeta-1, and Ihh gene expression was associated exclusively with the terminal differentiation of chondrocytes at the time of mineral formation in the extracellular matrix. In contrast, bFGF and PTHrP expression was observed in association with the onset of cyclin B2 expression and hypertrophy. This initial cluster of gene expression associated predominantly with matrix assembly and onset of cell proliferation is therefore characterized by expression of regulatory molecules distinct from those involved at hypertrophy. Together these results identify separate phases of coordinated gene expression associated with the development of the physis in endochondral bone formation.

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Available from: Elena V Tchetina, Sep 02, 2014
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    • "Further, qRT-PCR analysis revealed that expression of cartilaginous extracellular matrix proteins and transcription factors associated with chondrogenesis [45,46] were increased in Mgp-/- animals, and this increase was significantly attenuated in quercetin-treated Mgp-/- animals (Table 5). Of note, both early and late markers of chondrogenesis were attenuated by quercetin, implying that the prevention of chondrogenic transformation of VSM by this flavonoid in vivo is similar to its action in vitro. "
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    ABSTRACT: Cartilaginous metaplasia of vascular smooth muscle (VSM) is characteristic for arterial calcification in diabetes and uremia and in the background of genetic alterations in matrix Gla protein (MGP). A better understanding of the molecular details of this process is critical for the development of novel therapeutic approaches to VSM transformation and arterial calcification. This study aimed to identify the effects of bioflavonoid quercetin on chondrogenic transformation and calcification of VSM in the MGP-null mouse model and upon TGF-β3 stimulation in vitro, and to characterize the associated alterations in cell signaling. Molecular analysis revealed activation of β-catenin signaling in cartilaginous metaplasia in Mgp-/- aortae in vivo and during chondrogenic transformation of VSMCs in vitro. Quercetin intercepted chondrogenic transformation of VSM and blocked activation of β-catenin both in vivo and in vitro. Although dietary quercetin drastically attenuated calcifying cartilaginous metaplasia in Mgp-/- animals, approximately one-half of total vascular calcium mineral remained as depositions along elastic lamellae. Quercetin is potent in preventing VSM chondrogenic transformation caused by diverse stimuli. Combined with the demonstrated efficiency of dietary quercetin in preventing ectopic chondrogenesis in the MGP-null vasculature, these findings indicate a potentially broad therapeutic applicability of this safe for human consumption bioflavonoid in the therapy of cardiovascular conditions linked to cartilaginous metaplasia of VSM. Elastocalcinosis is a major component of MGP-null vascular disease and is controlled by a mechanism different from chondrogenic transformation of VSM and not sensitive to quercetin.
    Full-text · Article · Sep 2013 · PLoS ONE
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    • "It has been reported that growth factors such as TGF-b1, BMP-4 and FGF-2 are often required in the process of chondrogenesis [13]. Particularly, studies have reported that transforming growth factor-beta (TGF-b) plays an important role in chondrogenesis of MSCs [14] by stimulating chondrocyte proliferation while preventing cartilage hypertrophy [15]. In addition, it is well known that the cell delivery vehicle has an important role in the in vivo performance of MSCs and the success of the regenerative therapy. "
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    Full-text · Article · Jul 2013 · Acta biomaterialia
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    • "Link N can stimulate the synthesis of collagen in human articular cartilage and bovine IVD cells in vitro [28-30], as well as in the IVDs of rabbits in vivo [31]. Our previous results showed that Link N can also decrease the expression of type X collagen, a marker of chondrocyte hypertrophy [32], and stimulate the expression of type II collagen, a marker of cartilage and disc ECM [33], in human mesenchymal stem cells [34]. Thus, Link N has the potential to be used together with MSCs in promoting the formation of the type of ECM necessary for IVD repair. "
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