Altered integration of matrilin-3 into cartilage extracellular matrix in the absence of collagen IX.
The matrilins are a family of four noncollagenous oligomeric extracellular matrix proteins with a modular structure. Matrilins can act as adapters which bridge different macromolecular networks. We therefore investigated the effect of collagen IX deficiency on matrilin-3 integration into cartilage tissues. Mice harboring a deleted Col9a1 gene lack synthesis of a functional protein and produce cartilage fibrils completely devoid of collagen IX. Newborn collagen IX knockout mice exhibited significantly decreased matrilin-3 and cartilage oligomeric matrix protein (COMP) signals, particularly in the cartilage primordium of vertebral bodies and ribs. In the absence of collagen IX, a substantial amount of matrilin-3 is released into the medium of cultured chondrocytes instead of being integrated into the cell layer as in wild-type and COMP-deficient cells. Gene expression of matrilin-3 is not affected in the absence of collagen IX, but protein extraction from cartilage is greatly facilitated. Matrilin-3 interacts with collagen IX-containing cartilage fibrils, while fibrils from collagen IX knockout mice lack matrilin-3, and COMP-deficient fibrils exhibit an intermediate integration. In summary, the integration of matrilin-3 into cartilage fibrils occurs both by a direct interaction with collagen IX and indirectly with COMP serving as an adapter. Matrilin-3 can be considered as an interface component, capable of interconnecting macromolecular networks and mediating interactions between cartilage fibrils and the extrafibrillar matrix.
Published In/Presented At
Budde, B., Blumbach, K., Ylöstalo, J., Zaucke, F., Ehlen, H. W., Wagener, R., Ala-Kokko, L., Paulsson, M., Bruckner, P., & Grässel, S. (2005). Altered integration of matrilin-3 into cartilage extracellular matrix in the absence of collagen IX. Molecular and cellular biology, 25(23), 10465–10478. https://doi.org/10.1128/MCB.25.23.10465-10478.2005
Medicine and Health Sciences
Department of Pathology and Laboratory Medicine