Modulation of Collagen Fibrillogenesis by Dentinal Proteoglycans

Abstract

Studies have identified different pools of proteoglycan (PG) species present within the unmineralized matrix of the predentine, the transitional phase at the predentine-dentine interface and the mineralized dentine. These PGs alter with respect to the chemical nature of their glycosaminoglycan (GAG) chains and as a result of extracellular processing of the macromolecule in the matrix. The present study has examined the influence of the PGs isolated from these phases and the influence of the attached GAG chains, upon their ability to control collagen fibrillogenesis. PGs isolated from the three phases were characterized and determined to contain a mixture of decorin and biglycan. Results have indicated that predentine PGs, which are substituted with a higher proportion of dermatan sulfate, significantly delayed fibril formation while ultimately promoting the formation of thicker fibrils. Removal of the GAG chains further delayed fibrillogenesis, leading to the formation of thinner fibrils, compared with the collagen-only control. PGs isolated from predentine-dentine, which contained a higher proportion of chondroitin sulfate, also significantly delayed fibrillogenesis, resulting in thicker collagen fibrils. GAG chains attached to the predentine-dentine interface PGs played a role in the timing of fibrillogenesis with fibril formation initiated at the same time as the collagen control, but yielding thicker fibrils. Dentine PGs significantly inhibited fibrillogenesis and fibril thickness over concentrations of 50-25 microg/mL protein. In conclusion, the PGs isolated from the distinct phases have indicated differing roles in the orchestrated organization of the extracellular matrix during dentinogenesis, with roles for both the core protein and attached GAG chains indicated.

Collagen fibrillogenesis in tendon development: Current models and regulation of fibril assembly

“…Lumican and fibromodulin interact with fibrillar collagens and have been shown to retard fibril formation in vitro (Hedbom and Heinegard, 1993;Rada et al, 1993;Ezura et al, 2000). Fibromodulin, in particular, has been shown to bind to collagen monomers and delay their integration with laterally aggregating collagen type I fibrils in vitro (Vogel and Trotter, 1987;Scott, 1988;Hedbom and Heinegard, 1989;Hedlund et al, 1994;Scott, 1996;Font et al, 1998;Matheson et al, 2005;Milan et al, 2005;Goldberg et al, 2006;Kalamajski and Oldberg, 2007).…”

Fibromodulin-deficient Mice Display Impaired Collagen Fibrillogenesis in Predentin as Well as Altered Dentin Mineralization and Enamel Formation

“…Fmod is a latent TGFh modulator during skin development and wound healing (Soo et al 2000). In addition, like other SLRPs, it is most probably implicated in the lateral aggregation of collagen fibrils that orient fibrillogenesis (Scott 1988(Scott ,1996Milan et al 2005). Fmod and lumican bind to the same region on collagen type I fibrils (Svensson et al 2000).…”

The Role of Enzymes in Biomineralization Processes

“…Furthermore, a major role in collagen fibrillogenesis is attributed to proteoglycans [164][165][166][167]. Proteoglycans are involved in various biomineralization processes, such as the egg shell proteoglycan OC-116.…”