Collagen II from articular cartilage and annulus fibrosus

Abstract

Collagen I1 was isolated and characterized from hyaline cartilage (articular cartilage) and fibrocartilage (annulus fibrosus). Collagen I1 from the latter tissue has a substantially higher degree of hydroxylation and glycosylation than that isolated from articular cartilage. The higher degree of posttranslational modification was associated with a slower electrophoretic mobility, a greater resistance to mammalian collagenase digestion and a higher thermal stability. An increase of glycosylation accelerates the initial steps in fibril formation of collagen molecules but slows down the following lateral growth. The newly formed aggregates of collagen I1 from annulus fibrosus consisted of fibrils with a smaller diameter.Based on its histological appearance, cartilage is classified into three tissue entities, i. e. hyaline, elastic and fibrocartilage. Hyaline cartilage covers the articular surface of bone and supports the tracheal tubes, larynx and ventral ends of the ribs. Fibrocartilage is a transitional form between hyaline cartilage and fibrous connective tissue. It occurs in the menisci of joints, in the annulus fibrosus of intervertebral discs and in the attachment sites of tendons onto the bones [l]. Collagen, the main structural protein in both tissues, exhibits a high degree of organization based on fibrillar aggregates.Several factors have been suggested to play a role in the control of fibrillogenesis, such as the presence of proteoglycans [2], the mode of procollagen processing [3], the interaction of different collagen types [4] and non-collagenous proteins including integrins p]. Furthermore, experimental evidence showed that the posttranslational modification of collagen molecules plays a crucial role in the stability of individual molecules as well as the stabilization of collagen fibrils. Specifically, hydroxylation of prolyl residues determines the thermal stability of the triple helix of collagen molecules. Hydroxylation of lysyl residues contributes to the crosslinking of collagen molecules which, in turn, contributes to the biomechanical strength of collagen fibrils [6]. Recent circumstantial evidence provides further support that glycosylation of hydroxylysyl residues may regulate the diameter of collagen fibrils [7, 81. In this study, an approach was made to compare collagen I1 from hyaline cartilage (articular cartilage) and fibrocartilage (annulus fibrosus). The analysis showed that the collagen I1 from annulus fibrosus (AFII) has a substantially higher level of hydroxylation and glycosylation than the collagen I1 from articular cartilage (ACII). In order to clarify the influ- ence of different levels of posttranslational modification on the nature of collagen I1 molecules, their electrophoretic migration, thermal stability and susceptibility to mammalian collagenase were investigated. Additionally, we studied the impact of the varying pattern of collagen I1 modifications on the dynamics of the self-assembly and the structure of the fibrils formed in vitro. MATERIALS AND METHODS Extractio...

A simplified measurement of degraded collagen in tissues: Application in healthy, fibrillated and osteoarthritic cartilage

“…5). This is in agreement with the thermal unwinding temperature of soluble collagen type II, which is 41-42 °C (Danielsen, 1982;Yang et al, 1993). This supports the feasibility of aCT to digest de natured collagen selectively.…”

Biochemical and biophysical alterations of the 7S and NC1 domain of collagen IV from human diabetic kidneys

“…The sensitivity of amino acid analysis may be too low to detect the subtle changes expected in the amino acid composition of the modified domains. Formation of cross-links, however, had an impact on collagen triple helix stability and this has been shown previously for collagen II from intervertebral discs of elderly patients [22]. Our experiments indicated a denaturation with loss of the triple-helicity of the 7S domain already at room temperature.…”

“…The effects of carbohydrate-induced reactions in vitro on two distinct domains of collagen IV (7S domain and NC1 domain) have been reported recently [22]. Our study was aimed to describe biochemical and biophysical properties of the collagen IV crosslinking domains 7S and NC1 from human kidneys obtained from patients with diabetes mellitus Type II.…”

“…Glycation of proteins is associated with the formation of high-molecular aggregates that are stabilised by non-reducible cross-linking components [13, 17±18] with characteristic fluorescence spectra [6,19,20]. Circular dichroism (CD) spectroscopy studies of glycated proteins exhibited a damaging effect of the modifications on protein structure and stability [21,22].…”

“…Glycation of proteins is associated with the formation of high-molecular aggregates that are stabilised by non-reducible cross-linking components [13, 17±18] with characteristic fluorescence spectra [6,19,20]. Circular dichroism (CD) spectroscopy studies of glycated proteins exhibited a damaging effect of the modifications on protein structure and stability [21,22].In diabetic nephropathy the disordered morphology and functional deficiency of the glomerular basement membrane (GBM) has been explained by glycation of the collagen IV network providing the mechanical scaffold of the membrane texture. Collagen IV monomers consist of a collagenous major triplehelical domain with two specific cross-linking domains, the NC1 domain at the C-terminal end and the N-terminus the 7S domain [23±26], facilitating Diabetologia (1998) Summary Glycation of basement membrane collagen IV has been implicated as a major pathogenetic process leading to diabetic microvascular complications.…”