hydroxylysine and Osteogenesis-Imperfecta

Collagen is a macromolecule that has versatile roles in physiology, ranging from structural support to mediating cell signaling. Formation of mature collagen fibrils out of procollagen α-chains requires a variety of enzymes and chaperones in a complex process spanning both intracellular and extracellular post-translational modifications. These processes include modifications of amino acids, folding of procollagen α-chains into a triple-helical configuration and subsequent stabilization, facilitation of transportation out of the cell, cleavage of propeptides, aggregation, cross-link formation, and finally the formation of mature fibrils. Disruption of any of the proteins involved in these biosynthesis steps potentially result in a variety of connective tissue diseases because of a destabilized extracellular matrix. In this review, we give a revised overview of the enzymes and chaperones currently known to be relevant to the conversion of lysine and proline into hydroxyproline and hydroxylysine, respectively, and the O-glycosylation of hydroxylysine and give insights into the consequences when these steps are disrupted.

Topics: Animals; Arthrogryposis; Connective Tissue Diseases; Ehlers-Danlos Syndrome; Fibrillar Collagens; Glycosylation; Humans; Hydroxylation; Hydroxylysine; Hydroxyproline; Lysine; Osteogenesis Imperfecta; Proline; Protein Folding

Topics: C-Peptide; Chemical Phenomena; Chemistry; Collagen; Collagen Diseases; Copper; Ehlers-Danlos Syndrome; Genetic Variation; Humans; Hydroxylysine; Marfan Syndrome; Menkes Kinky Hair Syndrome; Mutation; Osteogenesis Imperfecta; Phenotype; Procollagen; Protein Biosynthesis; Protein-Lysine 6-Oxidase; Transcription, Genetic

Topics: Bone and Bones; Cells, Cultured; Chemical Phenomena; Chemistry; Collagen; Dipeptides; Fibroblasts; Forecasting; Humans; Hydroxylysine; Osteogenesis Imperfecta; Procollagen; Skin

Topics: Adolescent; Bone Diseases; Bone Matrix; Collagen; Humans; Hydroxylysine; Hydroxyproline; Osteogenesis Imperfecta; Peptides

The collagens are the major structural glycoproteins of connective tissues. A unique primary structure and a multiplicity of post-translational modification reactions are required for normal fibrillogenesis. The post-translational modifications include hydroxylation of prolyl and lysyl residues, glycosylation, folding of the molecule into triple-helical conformation, proteolytic conversion of precursor procollagen to collagen, and oxidative deamination of certain lysyl and hydroxylysyl residues. Any defect in the normal mechanisms responsible for the synthesis and secretion of collagen molecules or the deposition of these molecules into extracellular fibers could result in abnormal fibrillogenesis; such defects could result in a connective tissue disease. Recently, defects in the regulation of the types of collagen synthesized and in the enzymes involved in the post-translational modifications have been found in heritable diseases of connective tissue. Thus far, the primary heritable disorders of collagen metabolism in man include lysyl hydroxylase deficiency in Ehlers-Danlos syndrome type VI, p-collagen peptidase deficency in Ehlers-Danlos syndrome type VII, decreased synthesis of type III collagen in Ehlers-Danlos syndrome type IV, lysyl oxidase deficency in S-linked cutis laxa and Ehlers-Danlos syndrome type V, and decreased synthesis of type I collagen in osteogenesis imperfecta.

Topics: Aortic Diseases; Bone and Bones; Brain Diseases; Collagen; Connective Tissue; Cutis Laxa; Ehlers-Danlos Syndrome; Fascia; Genetic Linkage; Homocystinuria; Humans; Hydroxylysine; Hydroxyproline; Joints; Marfan Syndrome; Microbial Collagenase; Osteogenesis Imperfecta; Protein Biosynthesis; Protein Conformation; Protein-Lysine 6-Oxidase; Sex Chromosomes; Skin Abnormalities

The deletion of the alpha2 chain from type I collagen in the oim mouse model of osteogenesis imperfecta has been shown to result in a significant reduction in the mechanical strength of the tail tendon and bone tissue. However, the exact role of the alpha2 chain in reducing the mechanical properties is not clear. We now report that the stabilizing intermolecular cross-links in bone are significantly reduced by 27%, thereby contributing to the loss of tensile strength and the change in stress-strain profile. We also report that, in contrast to previous studies, the denaturation temperature of the triple helical molecule and the intact fibers are 2.6 degrees and 1.9 degrees C higher than the corresponding tail tendon collagen from wild-type mice. The increase in hydroxyproline content accounts, at least in part, for the increase in denaturation temperature. The alpha2 chain clearly plays an important part in stabilizing the type I collagen triple helix and fiber packing, but further studies are required to determine the precise mechanism.

Topics: Animals; Calcification, Physiologic; Collagen Type I; Cross-Linking Reagents; Disease Models, Animal; Female; Hydroxylysine; Male; Mice; Mice, Mutant Strains; Osteogenesis Imperfecta; Protein Denaturation; Tail; Tendons; Tensile Strength; Tibia

The brittleness of bone in patients with osteogenesis imperfecta (OI) has been attributed to an aberrant collagen network. However, the role of collagen in the loss of tissue integrity has not been well established. To gain an insight into the biochemistry and structure of the collagen network, the cross-links hydroxylysylpyridinoline (HP) and lysylpyridinoline (LP) and the level of triple helical hydroxylysine (Hyl) were determined in bone of OI patients (types I, III, and IV) as well as controls. The amount of triple helical Hyl was increased in all patients. LP levels in OI were not significantly different; in contrast, the amount of HP (and as a consequence the HP/LP ratio and the total pyridinoline level) was significantly increased. There was no relationship between the sum of pyridinolines and the amount of triple helical Hyl, indicating that lysyl hydroxylation of the triple helix and the telopeptides are under separate control. Cross-linking is the result of a specific three-dimensional arrangement of collagens within the fibril; only molecules that are correctly aligned are able to form cross-links. Inasmuch as the total amount of pyridinoline cross-links in OI bone is similar to control bone, the packing geometry of intrafibrillar collagen molecules is not disturbed in OI. Consequently, the brittleness of bone is not caused by a disorganized intrafibrillar collagen packing and/or loss of cross-links. This is an unexpected finding, because mutant collagen molecules with a random distribution within the fibril are expected to result in disruptions of the alignment of neighboring collagen molecules. Pepsin digestion of OI bone revealed that collagen located at the surface of the fibril had lower cross-link levels compared with collagen located at the inside of the fibril, indicating that mutant molecules are not distributed randomly within the fibril but are located preferentially at the surface of the fibril.

Topics: Adolescent; Adult; Amino Acids; Arginine; Biomarkers; Biopsy; Bone and Bones; Child; Child, Preschool; Collagen; Humans; Hydroxylysine; Infant; Lysine; Osteogenesis Imperfecta; Pepsin A; Pyridinium Compounds; Reference Values

The composition of the collagens secreted into the media of fibroblast cultures of 39 patients with osteogenesis imperfecta (OI) was the same in controls and OI cultures. An abnormal migration pattern of collagens upon SDS-PAGE was evident in one third of the cultures investigated. Lysyl and prolyl hydroxylation of HPLC-purified alpha 1(I) chains was elevated in about 60% of cultures. The degree of hydroxylation was highest in the lethal forms. The extent of lysyl and prolyl hydroxylation showed a strong correlation (r = 0.74, P < 0.001). While high levels of hydroxylation are frequently observed in OI patients, a direct correlation between lysyl or prolyl hydroxylation and fracture rate or growth retardation could not be established.

Topics: Adolescent; Adult; Body Height; Cells, Cultured; Child; Child, Preschool; Collagen; Female; Fibroblasts; Fractures, Bone; Humans; Hydroxylation; Hydroxylysine; Hydroxyproline; Infant; Lysine; Male; Middle Aged; Osteogenesis Imperfecta; Phenotype; Pregnancy; Proline

Transforming growth factor beta 1 (TGF-beta 1) is an osteotropic growth factor that is found in substantial concentration in bone. The authors studied the influence of TGF-beta 1 on the modification of lysine residues of collagen I. The degree of lysyl hydroxylation and lysyl glycosylation of newly synthesized collagen as well as steady-state levels of mRNA for both lysyl hydroxylase and collagens I and III were determined in human osteoblast-like cells in vitro. In normal human osteoblasts lysyl hydroxylation was decreased by TGF-beta 1 particularly in the collagen alpha 2-chain. This effect was paralleled by an increase in lysyl residues, whereas glycosylation was not affected. The mRNA for lysyl hydroxylase was reduced by one-third under the influence of TGF-beta 1. Additionally, the mRNAs for both procollagen I alpha-chains were stimulated by TGF-beta 1, whereas pro alpha 1 (III)-mRNA showed a decrease. Changes in the local regulatory activity of TGF-beta 1 may play a role in matrix maturation such as collagen type production and lysyl hydroxylation, the latter being altered in various pathological conditions, e.g. in generalized osteopenia.

Topics: Adult; Blotting, Northern; Cloning, Molecular; Collagen; DNA Probes; Extracellular Matrix; Gene Expression Regulation; Glycosylation; Humans; Hydroxylation; Hydroxylysine; Lysine; Osteoblasts; Osteogenesis Imperfecta; Procollagen; Procollagen-Lysine, 2-Oxoglutarate 5-Dioxygenase; Protein Processing, Post-Translational; RNA, Messenger; Transforming Growth Factor beta

Fibroblasts from many patients with osteogenesis imperfecta (OI) synthesize and secrete Type I collagen which is both overmodified and exhibits a decreased thermal denaturation temperature. We have examined the relationship between overmodification and decreased melting temperature in several favorable OI mutants by selectively inhibiting lysyl hydroxylase activity with the drug Minoxidil and comparing the melting profiles of the resultant undermodified collagen with untreated control. Minoxidil treatment causes an appreciable decrease in hydroxylysine with compensatory increases in lysine content, and the delayed sodium dodecyl sulfate-polyacrylamide gel electrophoretic mobility of the overmodified collagen chains becomes normal. However, the decreased melting temperature was unchanged from untreated OI control. When unhydroxylated collagen produced by normal control and OI fibroblasts incubated with alpha,alpha'-dipyridyl was examined, mutant OI molecules melted at a lower temperature than control. These data indicate that the decreased thermal denaturation temperature of OI mutant collagen is independent of post-translational overmodification of lysine or hydroxylysine. Presumably, substitutions for glycine in the Gly-X-Y structural motif distort the helix and produce lower melting temperatures by presently unknown mechanisms.

Topics: Collagen; Hot Temperature; Humans; Hydroxylysine; Lysine; Minoxidil; Mutation; Osteogenesis Imperfecta; Pepsin A; Protein Processing, Post-Translational

Collagen was extracted by pepsin treatment from various tissues and skin fibroblasts of 23 patients belonging to different types of osteogenesis imperfecta (OI), and characterized by molecular sieve and ion exchange chromatography, gel electrophoresis, and amino acid analysis. We found an elevated collagen III/I ratio in the skin of one patient with OI type I but almost normal values in skin fibroblasts of two other patients of this OI type. Five patients with OI type II had a normal collagen III/I ratio in their skin and skin fibroblasts, but the degree of hydroxylation of lysine residues in collagen I and III from their skin, bone, calvarium, and noncalcified calvarial tissue was increased. Patients belonging to OI types II, III, and IV had also considerable amounts of collagen III in their long bones, while bone tissue from controls contained only type I collagen. The content of type V in calcified tissues was virtually the same in controls and patients.

Topics: Adolescent; Adult; Child; Child, Preschool; Collagen; Fibroblasts; Humans; Hydroxylysine; Infant, Newborn; Lysine; Osteogenesis Imperfecta; Skin

Structurally abnormal type I collagen was identified in the dermis, bone, and cultured fibroblasts obtained from a baby with lethal perinatal osteogenesis imperfecta. Two-dimensional gel electrophoresis of the CNBr peptides demonstrated that the alpha 1(I)CB7 peptide from the alpha 1(I)-chain of type I collagen existed in a normal form and a mutant form with a more basic charge distribution. This heterozygous peptide defect was not detected in the collagens from either parent. The defect was localized to a 224-residue region at the NH2 terminus of the alpha 1(I)CB7 peptide by mammalian collagenase digestion. Analysis of unhydroxylated collagens produced in cell culture indicated that the mutant alpha 1(I)CB7 migrated faster on electrophoresis suggesting that the abnormality may be a small deletion or a mutation that alters sodium dodecyl sulfate binding. The post-translational hydroxylation of lysine residues was increased in the CB7 peptide and also in peptides CB3 and CB8 which are toward the NH2 terminus of the alpha 1(I)-chain. The COOH-terminal CB6 peptide was normally hydroxylated. These findings support the proposal that the lysine overhydroxylation resulted from a perturbation of helix propagation from the COOH to NH2 terminus of the collagen trimer caused by the structural defect in alpha 1(I)CB7.

Topics: Collagen; Cyanogen Bromide; Female; Humans; Hydroxylysine; Infant, Newborn; Isoelectric Point; Mutation; Osteogenesis Imperfecta; Peptide Fragments; Protein Conformation; Protein Processing, Post-Translational

Topics: Amino Acid Sequence; Base Sequence; Collagen; Cysteine; DNA; Fibroblasts; Humans; Hydroxylysine; Infant; Infant, Newborn; Male; Osteogenesis Imperfecta; Phenotype; Polymorphism, Genetic; Proteins

A male infant with pale-blue sclerae, who died at the age of 6 weeks through the aspiration of food, presented multiple fractures and deformation of the long tubular bones. The clinical and radiological findings and the course indicated osteogenesis imperfecta, type III, according to Sillence's classification. The family history was unremarkable. Light and electron microscopic studies of iliac crest bone obtained postmortem, showed an abrupt interruption of endochondral ossification, with an active periosteal ossification. In the region of the fractures, a mixed desmochondral callus was seen. The endoplasmic reticulum of the osteoblasts was markedly dilated, the mitochondria were swollen. The osteoid was reduced in quantity. A postmortem analysis of the collagen types I, II and III obtained from skin, cartilage and bone yielded chromatographically normal collagen constituents. An analysis of the amino acids of the collagen alpha-chains showed an increased hydroxylysine content. The radiological findings and the clinical course both indicated type III osteogenesis imperfecta: identical biochemical findings have been described only for type II. The morphological and biochemical findings described here may be a manifestation of a variable expressivity of type III osteogenesis imperfecta. On the other hand, heterogeneity of type II osteogenesis imperfecta cannot be ruled out.

Topics: Amino Acids; Bone and Bones; Cartilage; Chromatography, Ion Exchange; Collagen; Endoplasmic Reticulum; Humans; Hydroxylation; Hydroxylysine; Infant; Male; Mitochondrial Swelling; Osteoblasts; Osteogenesis Imperfecta; Proline; Skin

Osteogenesis imperfecta (OI) is a hereditary disease characterized by increased bone fragility and marked skeletal deformities. As a generalized connective tissue disorder, many patients present with other typical symptoms, such as blue sclerae, dentinogenesis imperfecta, impaired hearing, joint laxity, and easy bruising of the skin. According to clinical and genetic characteristics, Sillence classified four different groups. Metabolic alterations of connective tissue components are thought to be responsible for the pathogenesis of OI. Collagen, the main constituent of connective tissue, was analyzed in autoptic tissue and/or skin fibroblasts from patients with OI. In fibroblast culture of patients with OI group I, the range of synthesized collagen type III is elevated to 15-48% (normal up to 15%). Patients in groups II and III show an increased presence of hydroxylysine in alpha-chains of collagen types I and III. The hydroxylation of lysyl residues of the cartilage specific collagen type II is slightly elevated. In both groups, the hydroxypyroline content in all tested collagen types was normal. In our investigation, the collagen of patients with OI group IV appeared normal. Although the clinical features of patients with OI of all groups were not homogeneous, OI group III and some subtypes of group II had similar clinical courses and biochemical findings. In addition, there are patients with OI who present with clinical symptoms, but who cannot be classified into any of the known groups. For a better differentiation, biochemical examination of collagen should be performed complementary to clinical and genetic criteria.

Topics: Adolescent; Bone and Bones; Cartilage; Cells, Cultured; Child; Child, Preschool; Collagen; Fibroblasts; Humans; Hydroxylysine; Osteogenesis Imperfecta

Forty-four patients with Osteogenesis Imperfecta (O.I.) were divided into groups on the basis of clinical and genetic criteria and the alterations in collagen and glycosaminoglycans (GAG) in the subjects of each group were examined. The largest group of patients as affected with a mild form of O.I. and showed an increased ratio of type III to type I collagen in skin and an increase of the ratio of hydroxylysine diglycoside to monoglycoside in skin collagen. The group of patients affected with a severe nonlethal form of O.I. appeared to be heterogeneous both from a clinical and from a biochemical point of view. A marked increase of the diglycoside to monoglycoside ratio was observed in skin and urine, whereas the ratio of type III to type I collagen in skin was within the normal range or significantly decreased. Some of these patients also showed alterations involving proteoglycans, e.g. in urinary GAGs a decreased galactosamine to glucosamine ratio could be demonstrated. Similar and more marked alterations involving both collagen and GAG metabolism were observed in five children affected with a lethal form of O.I.

Topics: Collagen; Glycosaminoglycans; Humans; Hydroxylysine; Osteogenesis Imperfecta; Skin

The CNBr peptides of type I collagen from bone of a patient with lethal osteogenesis imperfecta and age-matched controls were isolated by molecular-sieve chromatography and their amino acid compositions were determined. No differences were found between the compositions of the peptides from the patient and those from the controls, except for an increase in the degree of hydroxylation of lysine in all peptides from the patient. Type I collagen CNBr peptides from chick-embryo skin [Barnes, Constable Morton & Kodicek (1971) Biochem. J. 125, 925--928] and guinea-pig scar tissue [Shuttleworth, Forrest & Jackson (1975) Biochim. Biophys. Acta 379, 207--216] also have an increased degree of hydroxylation of lysine with an otherwise normal amino acid composition, and it was believed that this could be an embryonic form of collagen. As a similar collagen was present in the bones of the patient studied, it seems possible that the same 'embryonic' collagen is synthesized during development, in repair process and also in genetic disorders of collagen metabolism.

Topics: Amino Acids; Chemical Phenomena; Chemistry; Chromatography, Gel; Collagen; Cyanogen Bromide; Electrophoresis, Polyacrylamide Gel; Humans; Hydroxylysine; Infant; Lysine; Osteogenesis Imperfecta; Peptide Fragments

The composition, cross-linking, and thermal stability of the collagens were determined in bone and skin biopsies from 4 patients with moderate to severe forms of osteogenesis imperfecta (OI). The major modification observed with respect to control subjects was an overhydroxylation of lysine in type I bone collagen (hydroxylysine content doubled in three patients and increased by 50% in the last patient). This overhydroxylation is confirmed by a similar increase in the dihydroxylated cross-link of bone collagen: the dehydrodihydroxylysinonorleucine. The type II collagen from cartilage and the pepsin-soluble collagens from the skin of these patients contained the normal amount of hydroxylysine. A small amount of type III collagen has been found in three patients, while only in one patient a slight increase in the type III/type I collagen ratio was observed in skin. In all patients the thermal stability of the collagen triple helix, measured by differential scanning calorimetry, was normal in both bone and skin. Although in at least three patients the clinical features allowed us to classify our patients into two different groups (Sillence et al., 1979 classification--groups I and III), the biochemical results are similar, suggesting that the overhydroxylation of the lysine in type I bone collagen is a common feature of severe forms of osteogenesis imperfecta.

Topics: Adolescent; Bone and Bones; Calorimetry, Differential Scanning; Child; Child, Preschool; Collagen; Densitometry; Electrophoresis, Polyacrylamide Gel; Female; Hot Temperature; Humans; Hydroxylysine; Hydroxyproline; Lysine; Male; Osteogenesis Imperfecta; Skin

Topics: Collagen; Collagen Diseases; Ehlers-Danlos Syndrome; Extracellular Space; Genes; Humans; Hydroxylysine; Hydroxyproline; Osteogenesis Imperfecta; Procollagen; Protein Biosynthesis; RNA, Messenger

Topics: 2-Aminoadipic Acid; Animals; Aorta; Bone and Bones; Calcium; Chemical Phenomena; Chemistry; Chickens; Collagen; Histidine; Humans; Hydroxylysine; Lysine; Macromolecular Substances; Osteogenesis Imperfecta; Phosphates; Protein-Lysine 6-Oxidase; Rickets; Vitamin D Deficiency

Collagen from bone (femur and calvarium), rib cartilage, skin, tendon, sclera, and cornea has been isolated and purified from a deceased 4-day-old infant with osteogenesis imperfecta congenita. Amino acid analysis indicated that the content of hydroxylysine was doubled in bone collagen and increased by 55% in that of cartilage as compared with age-matched normal tissues. The levels of covalently bound glucose and galactose were proportionately increased in both collagens. Collagen purified from other tissues revealed smaller increases in lysyl hydroxylation. These data suggest that at least one form of osteogenesis imperfecta congenita is associated with a molecular alteration of collagen involving hydroxy-lysine and that this alteration is particualrly marked in collagens obtained from calcifying tissues.

Topics: Amino Acids; Bone and Bones; Cartilage; Cells, Cultured; Collagen; Cornea; Female; Fibroblasts; Galactose; Glucose; Humans; Hydroxylysine; Infant, Newborn; Osteogenesis Imperfecta; Sclera; Skin; Tendons

Topics: Alanine; Amino Acids; Bone and Bones; Child; Collagen; Dentin; Dentinogenesis Imperfecta; Glycine; Humans; Hydroxylysine; Hydroxyproline; Infant, Newborn; Male; Molar; Osteogenesis Imperfecta; Proline; Skull