Distribution of Small Integrin-binding Ligand, N-linked Glycoproteins (SIBLING) in the Articular Cartilage of the Rat Femoral Head

• Published in: The journal of histochemistry and cytochemistry Vol. 58; no. 11; pp. 1033 - 1043
• Main Authors: Sun, Yao, Ma, Su, Zhou, Jin, Yamoah, Albert K., Feng, Jian Q., Hinton, Robert J., Qin, Chunlin
• Format: Journal Article
• Language: English
• Published: Los Angeles, CA SAGE Publications 01.11.2010; Histochemical Society
• Subjects: Aging; Animals; Cartilage, Articular - growth & development; Cartilage, Articular - metabolism; Chondrogenesis; Extracellular Matrix Proteins - metabolism; Femur Head - growth & development; Integrin-Binding Sialoprotein; Male; Osteogenesis; Osteopontin - metabolism; Phosphoproteins - metabolism; Rats; Rats, Sprague-Dawley; Sialoglycoproteins - metabolism; femoral head; bone sialoprotein; osteopontin; cartilage; dentin sialophosphoprotein; dentin matrix protein 1; chondrogenesis; proteoglycan
• ISSN: 0022-1554; 1551-5044
• DOI: 10.1369/jhc.2010.956771

The small integrin-binding ligand, N-linked glycoprotein (SIBLING) family is closely related to osteogenesis. Until recently, little was known about their existence in articular cartilage. In this study, we systematically evaluated the presence and distribution of four SIBLING family members in rat femoral head cartilage: dentin matrix protein 1 (DMP1), bone sialoprotein (BSP), osteopontin (OPN), and dentin sialophosphoprotein (DSPP). First, non-collagenous proteins were extracted and then separated by ion-exchange chromatography. Next, the protein extracts eluted by chromatography were analyzed by Stains-all staining and Western immunoblotting. IHC was used to assess the distribution of these four SIBLING family members in the femoral head cartilage. Both approaches showed that all the four SIBLING family members are expressed in the femoral head cartilage. IHC showed that SIBLING members are distributed in various locations throughout the articular cartilage. The NH2-terminal fragments of DMP1, BSP, and OPN are present in the cells and in the extracellular matrix, whereas the COOH-terminal fragment of DMP1 and the NH2-terminal fragment of DSPP are primarily intracellularly localized in the chondrocytes. The presence of the SIBLING family members in the rat femoral head cartilage suggests that they may play important roles in chondrogenesis.