Collagen XI chain misassembly in cartilage of the chondrodysplasia (cho) mouse

Abstract

Molecular mechanisms controlling the assembly of cartilage-specific types II, IX and XI collagens into a heteropolymeric network of uniformly thin, unbanded fibrils are not well understood, but collagen XI has been implicated. The present study on cartilage from the homozygous chondrodysplasia (cho/cho) mouse adds support to this concept. In the absence of α1(XI) collagen chains, thick, banded collagen fibrils are formed in the extracellular matrix of cho/cho cartilage. A functional knock-out of the type XI collagen molecule has been assumed. We have re-examined this at the protein level to see if rather than a complete knock-out, alternative type XI chain assemblies were formed. Mass spectrometry of purified triple helical collagen from the rib cartilage of cho/ cho mice identified α1(V) and α2(XI) chains. These chains were recovered in roughly equal amounts based on Coomassie blue staining of SDS-PAGE gels, in addition to α1(II)/α3(XI) collagen chains. Using telopeptide-specific antibodies and Western blot analysis, it was further shown that type V/ XI trimers were present in the matrix cross-linked to each other and to type II collagen molecules to form heteropolymers. Cartilage from heterozygous (cho/+) mice contained a mix of α1(V) and α1 (XI) chains and a mix of thin and thick fibrils on transmission electron microscopy. In summary, the results imply that native type XI collagen molecules containing an α1(XI) chain are required to form uniformly thin fibrils and support a role for type XI collagen as the template for the characteristic type II collagen fibril network of developing cartilage.

Craniofacial cartilage morphogenesis requires zebrafish col11a1 activity

“…Such abnormal large fibrils were also described in the cho cartilage (Seegmiller and Monson, 1982;Li et al, 1995). In cho mice, an alternative hybrid collagen XI molecule was shown to assemble in which the closely related collagen V α1 chain replaces the missing collagen XI α1 chain (Fernandes et al, 2007). They concluded that the At 15 hpf, dlx2a is expressed in the three neural crest streams in wild type embryos (C) and in morphants (D) though reduced signal is observed.…”

A Role for Prolyl 3-Hydroxylase 2 in Post-translational Modification of Fibril-forming Collagens

“…Individual collagen ␣-chains were cut out and subjected to ingel trypsin digestion (26). Electrospray MS was performed on the tryptic peptides using an LCQ Deca XP ion trap mass spectrometer equipped with in-line LC (ThermoFinnigan) using a C8 capillary column (300 ϫ 150 mm; Grace Vydac 208MS5.315) eluted at 4 l/min.…”

Advances in collagen cross-link analysis

“…In the lower left panel, the α1(XI) N-telopeptide antiserum selectively bound to the α3(XI) α-chain on a Western blot and the α2(XI) N-telopeptide antiserum to the α1(XI) α-chain. These antisera can be used to determine the molecular binding partners of the N-telopeptides of type XI collagen chains present in more complex cartilages [28] or, for example, engineered tissue constructs induced in vivo or grown in vitro.…”