hydroxylysine and 5-5--dihydroxylysylnorleucine

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

Keloid is a tissue with an excessive accumulation of collagen. In this study, we have partially characterized post-translational modifications of type I collagen in human keloid in order to pursue their potential involvement in this pathology. The levels of lysyl hydroxylation of the helical portions of alpha 1 and alpha 2 chains of type I collagen in keloid were significantly higher than those of normal, while the levels of prolyl hydroxylation were identical between these two groups. The contents of the major reducible cross-links in dermal collagen, dehydro-hydroxylysinonorleucine and dehydro-histidinohydroxymero-desmosine, were both significantly higher in keloids (up to sixfold) than those of normal. In addition, significant amounts of hydroxylysine-aldehyde derived cross-links that are characteristic of skeletal tissue collagens, dehydro-dihydroxylysinonorleucine (about 0.3 mole/mole of collagen) and pyridinoline (about 0.1 mole/mole of collagen), were found in keloids. These results indicate that keloid-forming cells are phenotypically different from those in normal dermis and that the collagen produced is highly cross-linked. The increased cross-linking provides the fibrils with more stability that may result in an accumulation of collagen.

Topics: Adult; Amino Acids; Collagen; Cross-Linking Reagents; Desmosine; Dipeptides; Histidine; Humans; Hydroxylation; Hydroxylysine; Hydroxyproline; Keloid; Middle Aged; Protein Processing, Post-Translational; Protein Structure, Secondary; Skin

Rat lung collagen was labelled in vivo by a single intraperitoneal injection of [3H]lysine at several key timepoints in lung development: days 11 (alveolar proliferation), 26 (start of equilibrated growth), 42 (end of equilibrated growth), and 100 (adult lung structure present). The rates of deposition of labelled hydroxylysine and the difunctional, Schiff base-derived crosslinks hydroxylysinonorleucine (HLNL) and dihydroxylysinonorleucine (DHLNL) were quantified. We also measured total lung content of the trifunctional, mature crosslink hydroxypyridinium (OHP) in these same animals. While the relative rates of accumulation of labelled collagen [3H]hydroxylysine differed by a factor of about 6 at the different times of injection of labelled precursor, quantitative and qualitative patterns of collagen crosslinking were very similar at all of the lung developmental stages studied. Furthermore, there was little or no breakdown of the lung collagen pool as defined by the presence of labelled crosslinks; changes in lung DHLNL content could be completely accounted for by its maturation to OHP, regardless of the age of the rats when injected with the radioactive precursor. We conclude that mature, crosslinked collagen in the lungs of rats, which is obligatorily an extracellular pool, is not being degraded at a measurable rate. Therefore, studies of others that have shown apparent high rates of breakdown of newly synthesized collagen in lungs of whole animals using different methods are probably not reflective of the metabolic fate of total lung collagen, and may indicate that degradation of normal lung collagen occurs predominantly or exclusively intracellularly.

Topics: Animals; Collagen; Dipeptides; Female; Hydroxylysine; Isotope Labeling; Lung; Lysine; Pregnancy; Rats; Rats, Inbred Strains; Tritium

Collagen crosslinks in neonatal rats were labelled in vivo by a single intraperitoneal injection of 200 microCi of [14C]lysine. Rats were killed at times ranging from 30 minutes to 10 weeks after injection. Whole skin, tendon, and bone were analyzed, after reduction and hydrolysis, for collagen crosslink content by HPLC. Crosslinks and amino acids were visualized by their incorporation of radioactivity from [14C]lysine and also fluorometrically by post-column derivatization with o-phthalaldehyde. The incorporation of 14C from labelled lysine into the principal difunctional reducible crosslinks, N6.6'-dehydro-5,5'-dihydroxylysinonorleucine and N6.6'-dehydro-5-hydroxylysinonorleucine, increased most rapidly between 4 and 12 hours after injection, results similar to those observed by others studying crosslink biosynthesis in vitro. Incorporation of 14C into the tetrafunctional crosslink histidinohydroxymerodesmosine proceeded more slowly than it did for the difunctional crosslinks. Values for the amount of radioactivity incorporated into the various crosslinks reached an apparent constant value between 3 and 5 days after injection for all three tissues studied. These values remained approximately constant for the duration of the experiment except for HHMD in tendon, which showed an increase in incorporated radioactivity at 8 and 10 weeks after injection. Direct chemical quantification of these same crosslinks by determination of the fluorescence of their o-phthalaldehyde adducts was also performed. We conclude that in vivo labelling of collagen crosslinks can be studied, at least in rapidly growing neonates, after a single injection of radioactive lysine. The results of such studies support previous suggestions by others about the rate of formation of difunctional crosslinks based upon studies using in vitro systems. Our results further suggest that formation of the tetrafunctional reducible crosslink histidinohydroxymerodesmosine proceeds relatively rapidly in vivo. Finally, we conclude that such labelled crosslinks are apparently quite stable after biosynthesis, suggesting the possibility of studies of the metabolic fate of collagen crosslinks over appreciable fractions of the lifetime of a rat.

Topics: Amino Acids; Animals; Animals, Newborn; Bone and Bones; Chromatography, High Pressure Liquid; Collagen; Desmosine; Dipeptides; Histidine; Hydroxylysine; Kinetics; Lysine; Macromolecular Substances; Rats; Rats, Inbred Strains; Skin; Tendons

The palmar aponeurosis of patients affected with Dupuytren's disease was examined for collagen characteristics with regard to extractability, polymorphism, and posttranslational modifications, and the results were compared with those from normal subjects. The increased proportion of type III collagen relative to type I collagen in the affected tissue confirmed the previous findings in this disease. A slight but significant increase in a ratio of glucosylgalactosylhydroxylysine to galactosylhydroxylysine in the Dupuytren's tissue may be interpreted by the increase in the content of type III collagen. The affected tissue contained increased amounts of dihydroxylysinonorleucine as the reducible cross-link of collagen. These data support the view that Dupuytren's tissue contains collagen resembling that in granulation and embryonic tissues. Pyridinoline was shown to occur in normal and affected aponeurosis. No change in its content suggests that this cross-link is not involved in the pathogenesis of contracture in this disease.

Topics: Amino Acids; Collagen; Dipeptides; Dupuytren Contracture; Hand; Humans; Hydroxylysine; Male; Polymorphism, Genetic; Solubility; Tendons

Biopsies of a cutaneous osteoma and of normal-looking skin from a 1-year-old girl were studied for histological appearance and collagen biochemistry. The mineralized tissue contained a matrix similar to bone: Only type I collagen, with a hydroxylysine content (0.48%) higher than in the skin (0.35%) and dihydroxylysinonorleucine as the major reducible crosslink. As expected, the normal skin adjacent to the lesions contained type I and type III collagen and as major crosslinks hydroxylysinonorleucine and histidinohydroxymerodesmosine. Histological studies showed the presence of woven bone with very little trabeculation. Numerous active osteoblasts were laying down a rapidly calcified non-lamellar matrix. Osteocytes and multinucleated osteoclasts were also noted. The study demonstrates the osseous nature of the lesion and suggests that an abnormal cell differentiation is associated with this form of osteoma.

Topics: Bone and Bones; Collagen; Desmosine; Dipeptides; Female; Histidine; Humans; Hydroxylysine; Infant; Infant, Newborn; Osteoma; Skin Neoplasms

Topics: Amino Acids; Animals; Bone and Bones; Castration; Collagen; Dipeptides; Estradiol; Hydroxylysine; Male; Mice

Topics: Adolescent; Adult; Aorta; Collagen; Cyanogen Bromide; Dipeptides; Humans; Hydroxylysine; In Vitro Techniques; Male; Marfan Syndrome; Middle Aged; Norleucine; Skin

Topics: Amino Acid Sequence; Amino Acids; Animals; Borohydrides; Cattle; Collagen; Cross-Linking Reagents; Dentin; Dipeptides; Hydroxylysine; Norleucine; Peptide Fragments; Pyridinium Compounds; Trypsin

Catechol analogs inhibit the formation of hydroxylysine-derived intermolecular collagen cross links in tissue cultures of chick embryo calvaria. Formation of intermolecular collagen cross links was measured following incorporation of [14C]lysine, reduction with sodium borohydride, and elution from an ion exchange column with a pyridine-formate gradient. Cultures grown in the presence of 10(-3) M catechol, 10(-3) M dopamine, 10(-3) M L-dopa, or 10(-3) M D,L-serine-(2,3,4-trihydroxybenzyl)-hydrazide demonstrated between 43 and 84% inhibition of hydroxylysine formation. Collagen biosynthesis was not diminished in these cultures as compared to controls without additions or with beta-aminopropionitrile when measured by collagenase digestion. The formation of hydroxylysine-derived intermolecular cross links was inhibited 34 to 93% for 5,5'-dihydroxylysinonorleucine and 7 to 71% for 5-hydroxylysinonorleucine. The catechol analogs also inhibit the activity of lysyl hydroxylase as measured by specific tritium release as triated water from an L-[4,5-3H]lysine-labeled unhydroxylated collagen substrate prepared from chick calvaria. Since catechol analogs inhibit the formation of hydroxylysine in a cell-free assay, these compounds must pass into the cells of calvaria in this culture system to inhibit intracellular hydroxylysine formation and subsequently to diminish the reducible intermolecular cross links of the newly synthesized collagen.

Topics: Aminopropionitrile; Animals; Catechols; Chick Embryo; Collagen; Culture Techniques; Depression, Chemical; Dipeptides; Dopamine; Hydroxylysine; Levodopa; Norleucine; Protein-Lysine 6-Oxidase; Skull