Collagens—structure, function, and biosynthesis, 2003
Collagen Metabolism Compartimentation
Dioxygenase Reaction Substrates
Alteration in the extent of collagen I hydroxylation, isolated from femoral heads of women with a femoral neck fracture caused by osteoporosis. 1997
- The aim of this study was to investigate the extent of lysyl and prolyl hydroxylation of collagen I in osteoporosis and compare it with collagen I from "bone healthy" individuals. Collagen I was isolated from femoral heads of osteoporotic women, from women suffering from osteoarthrosis of the hip, and from healthy women 60-85 years of age. The femoral heads were dissected into compact and trabecular bone of the neck region and from trabecular bone of the head region, and collagen I was extracted by limited pepsin digestion. The amino acid analysis of individual alpha-chains showed a remarkably higher degree of hydroxylation of lysine residues both in the alpha1(I)- and in the alpha2(I)-chains in osteoporotic bone compared with osteoarthrotic and "normal" bone, whereas the prolyl hydroxylation was nearly unchanged. The lysyl overhydroxylation was observed in the compact as well as in the trabecular bone of osteoporotic femoral heads. These biochemical alterations may play a crucial role in the pathogenesis of osteoporosis.
Osteoporosis in longstanding acromegaly: characteristic changes of vertebral trabecular architecture and bone matrix composition. 1991
- Although it is now 60 years after Erdheim's (1931) detailed description of vertebral alterations in severe acromegaly, it is still unclear whether osteoporosis is a consistent feature of acromegalic bone disease or not. We studied the vertebral trabecular bone of a 44-year-old woman who had suffered active acromegaly for more than 20 years, and compared it with 17 normal as well as 2 osteoporotic controls. Histomorphometry revealed a very low trabecular bone volume and thus documented the presence of osteoporosis. The mean trabecular plate thickness was strikingly increased in acromegaly (possibly caused in part by a low-dose fluoride treatment), whereas it was normal or reduced in the osteoporotic controls. The meticulous analysis showed islands of cartilaginous tissue in the core of the acromegalic trabeculae which were not present in any other sample. In these areas collagen II was detected by immunohistochemistry. Biochemical analysis revealed that collagen II accounted for 7% of the total collagenous matrix. The degree of hydroxylation of lysyl residues of collagen I was close to the average value of all control samples studied. Our data show that osteoporosis can occur in acromegaly and that it is characterized by unusual architectural and compositional features. These findings challenge the prevailing view that the matrix of osteoporotic bone always shows a normal composition.
Overhydroxylation of lysyl residues is the initial step for altered collagen cross-links and fibril architecture in fibrotic skin. 1999
^ The results provide convincing evidence that morphometric changes associated with osteopenia in adult bone are accompanied by an altered level of lysyl hydroxylation of the alpha 2(I)-chain of collagen I.
Regional alterations of type I collagen in rat tibia induced by skeletal unloading.2002
- The collagen cross-linking and the extent of lysine (Lys) hydroxylation in unloaded bones were significantly altered in proximal epiphysis, diaphysis, and, in particular, proximal metaphysis but not in distal regions.
Matched in Chemicals: Collagen Type I.
The role of small leucine-rich proteoglycans in collagen fibrillogenesis
Sebastian Kalamajski, , 2010
- Small leucine-rich proteoglycans/proteins (SLRPs) are associated with collagen fibril formation, and therefore important for the proper formation of extracellular matrices. SLRPs are differentially expressed in tissues and during pathological conditions, contributing to the development of connective tissue properties. The binding of SLRPs to collagens have recently been characterized, and may give some clues to the significance of these interactions. In this mini review, we summarize published work in this field, and propose several mechanisms for how SLRPs can control collagen matrix structure and function. SLRPs appear to influence collagen cross-linking patterns. We also propose that the SLRP-collagen interactions can assist in the process of juxtaposing the collagen monomers by steric hindrance or by directly connecting two collagen monomers during the fibril growth.