Assembly of collagen types II, IX and XI into nascent hetero-fibrils by a rat chondrocyte cell line.
The cell line, RCS-LTC (derived from the Swarm rat chondrosarcoma), deposits a copious extracellular matrix in which the collagen component is primarily a polymer of partially processed type II N-procollagen molecules. Transmission electron microscopy of the matrix shows no obvious fibrils, only a mass of thin unbanded filaments. We have used this cell system to show that the type II N-procollagen polymer nevertheless is stabilized by pyridinoline cross-links at molecular sites (mediated by N- and C-telopeptide domains) found in collagen II fibrils processed normally. Retention of the N-propeptide therefore does not appear to interfere with the interactions needed to form cross-links and mature them into trivalent pyridinoline residues. In addition, using antibodies that recognize specific cross-linking domains, it was shown that types IX and XI collagens, also abundantly deposited into the matrix by this cell line, become covalently cross-linked to the type II N-procollagen. The results indicate that the assembly and intertype cross-linking of the cartilage type II collagen heteropolymer is an integral, early process in fibril assembly and can occur efficiently prior to the removal of the collagen II N-propeptides.
Fernandes
Russell J
RJ
Department of Orthopedics and Sports Medicine, University of Washington, Seattle, WA 98195, USA. rjf@u.washington.edu
Schmid
Thomas M
TM
Eyre
David R
DR
D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D000818:Animals; D019902:Chondrocytes / Q000378:metabolism* / Q000648:ultrastructure; D024043:Collagen Type II / Q000096:biosynthesis* / Q000737:chemistry / Q000648:ultrastructure; D024081:Collagen Type IX / Q000096:biosynthesis* / Q000737:chemistry / Q000648:ultrastructure; D024161:Collagen Type XI / Q000096:biosynthesis* / Q000737:chemistry / Q000648:ultrastructure; D010455:Peptides / Q000737:chemistry; D051381:Rats; D014407:Tumor Cells, Cultured
D000596:Amino Acids; D024043:Collagen Type II; D024081:Collagen Type IX; D024161:Collagen Type XI; D010455:Peptides; C015484:pyridinoline