Dysplastic Histogenesis of Cartilage Growth Plate by Alteration of Sulphation Pathway: A Transgenic Model

Abstract

Mutations in the diastrophic dysplasia sulphate transporter (dtdst) gene causes different forms of chondrodysplasia in the human. The generation of a knock-in mouse strain with a mutation in dtdst gene provides the basis to study developmental dynamics in the epiphyseal growth plate and long bone growth after impairment of the sulphate pathway. Our microscopical and histochemical data demonstrate that dtdst gene impairment deeply affects tissue organization, matrix structure, and cell differentiation in the epiphyseal growth plate. In mutant animals, the height of the growth plate was significantly reduced, according to a concomitant decrease in cell density and proliferation. Although the pathway of chondrocyte differentiation seemed complete, alteration in cell morphology compared to normal counterparts was detected. In the extracellular matrix, it we observed a dramatic decrease in sulphated proteoglycans, alterations in the organization of type II and type X collagen fibers, and premature onset of mineralization. These data confirm the crucial role of sulphate pathway in proteoglycan biochemistry and suggest that a disarrangement of the extracellular matrix may be responsible for the development of dtdts cartilage dysplasia. Moreover, we corroborated the concept that proteoglycans not only are structural components of the cartilage architecture, but also play a dynamic role in the regulation of chondrocyte growth and differentiation.

Regulated transport of sulfate and oxalate by SLC26A2/DTDST

“…Mutations in hSLC26A2/DTDST cause several related clinical phenotypes of chondrodysplasia (22,35). A related murine phenotype was generated by genetic knock-in of a mutation homologous to a human mutation associated with disease of moderate severity (10,14). The several hSLC26A2 disease mutations that have been subjected to functional study exhibited decreased SO 4 2Ϫ uptake into oocytes (29) or HEK-293 cells (28).…”

The SLC26 gene family of anion transporters and channels

“…An SLC26A2 chondrodysplasia has been partially phenocopied in the Slc26a2 A386V knock-in mouse, which exhibited post-natal growth retardation, reduced mobility, and 50% mortality by P21 associated with skeletal abnormalities and reduced epiphyseal growth plate thickness. Chondrocyte proliferation and differentiation were delayed, and cultured chondrocytes were nearly devoid of SO 4 2− uptake (Forlino et al, 2005), reflecting in vivo chondrocyte inability to utilize extracellular cysteine as a source of SO 4 2− for macromolecular sulfation (Pecora et al, 2006), and leading to undersulfated proteoglycans of cells and matrix, disorganization of collagen fibers, premature onset of mineralization (Cornaglia et al, 2009) and failure of fibronectin matrix assembly (Galante and Schwarzbauer, 2007). BMP-2 transcriptionally up-regulated SLC26A2 in C3H10T1/2 chondrocytes through interactions with a xenobiotic response element, and binding sites for SP-1 and CFBA1 in the SLC26A2 promoter (Kobayashi et al, 1997).…”

Clinical and molecular characterization of Diastrophic Dysplasia in the Portuguese population

“…Recent studies in transgenic mice showed that proteoglycans are not only structural components of cartilage architecture, but also play a dynamic role in the regulation of chondrocyte growth and differentiation (13).…”