title: N-Homocysteinylation impairs collagen cross-linking in cystathionine β-synthase-deficient mice: a novel mechanism of connective tissue abnormalities.
abstract: Cystathionine β-synthase (CBS) deficiency, a genetic disorder in homocysteine (Hcy) metabolism in humans, elevates plasma Hcy-thiolactone and leads to connective tissue abnormalities that affect the cardiovascular and skeletal systems. However, the underlying mechanism of these abnormalities is not understood. Hcy-thiolactone has the ability to form isopeptide bonds with protein lysine residues, which generates N-homocysteinylated protein. Because lysine residues are involved in collagen cross-linking, N-homocysteinylation of these lysines should impair cross-linking. Using a Tg-I278T Cbs-/-mouse model of hyperhomocysteinemia (HHcy) which replicates the connective tissue abnormalities observed in CBS-deficient patients, we found that N-Hcy-collagen was elevated in bone, tail, and heart of Cbs-/-mice, whereas pyridinoline cross-links were significantly reduced. Plasma deoxypyridinoline cross-link and cross-linked carboxyterminal telopeptide of type I collagen were also significantly reduced in the Cbs-/-mice. Lysine oxidase activity and mRNA level were not reduced by the Cbs-/-genotype. We also showed that collagen carries S-linked Hcy bound to the thiol of N-linked Hcy. In vitro experiments showed that Hcy-thiolactone modifies lysine residues in collagen type I α-1 chain. Residue K160, located in the nonhelical N-telopeptide region and involved in pyridinoline cross-link formation, was also N-homocysteinylated in vivo Taken together, our findings showed that N-homocysteinylation of collagen in Cbs-/-mice impairs its cross-linking. These findings explain, at least in part, connective tissue abnormalities observed in HHcy.-Perła-Kajan, J., Utyro, O., Rusek, M., Malinowska, A., Sitkiewicz, E., Jakubowski, H. N-Homocysteinylation impairs collagen cross-linking in cystathionine β-synthase-deficient mice: a novel mechanism of connective tissue abnormalities.
authors.affiliation: Department of Biochemistry and Biotechnology, University of Life Sciences, Poznań, Poland.
authors.forename: Joanna
authors.initials: J
authors.lastname: Perła-Kajan
authors.affiliation: Institute of Bioorganic Chemistry, Poznań, Poland.
authors.forename: Olga
authors.initials: O
authors.lastname: Utyro
authors.affiliation: Department of Microbiology, Biochemistry and Molecular Genetics, International Center for Public Health, Rutgers-New Jersey Medical School, Rutgers University, Newark, New Jersey, USA; and.
authors.forename: Marta
authors.initials: M
authors.lastname: Rusek
authors.affiliation: Proteomics Laboratory, Biophysics Department, Institute of Biochemistry and Biophysics, Warsaw, Poland.
authors.forename: Agata
authors.initials: A
authors.lastname: Malinowska
authors.affiliation: Proteomics Laboratory, Biophysics Department, Institute of Biochemistry and Biophysics, Warsaw, Poland.
authors.forename: Ewa
authors.initials: E
authors.lastname: Sitkiewicz
authors.affiliation: Department of Biochemistry and Biotechnology, University of Life Sciences, Poznań, Poland; jakubows@rutgers.edu.|Institute of Bioorganic Chemistry, Poznań, Poland.|Department of Microbiology, Biochemistry and Molecular Genetics, International Center for Public Health, Rutgers-New Jersey Medical School, Rutgers University, Newark, New Jersey, USA; and.
authors.forename: Hieronim
authors.initials: H
authors.lastname: Jakubowski
mesh_terms: D000818:Animals; D024042:Collagen Type I / Q000378:metabolism*; D000090602:Collagen Type I, alpha 1 Chain; D003238:Connective Tissue / Q000378:metabolism*; D003541:Cystathionine beta-Synthase / Q000235:genetics / Q000378:metabolism*; D006710:Homocysteine / Q000031:analogs & derivatives* / Q000378:metabolism; D006712:Homocystinuria / Q000235:genetics; D020138:Hyperhomocysteinemia / Q000378:metabolism*; D008239:Lysine / Q000378:metabolism; D018345:Mice, Knockout; D010455:Peptides / Q000378:metabolism
chemical_list: C000716127:COL1A1 protein, human; D024042:Collagen Type I; D000090602:Collagen Type I, alpha 1 Chain; D010455:Peptides; C052929:collagen type I trimeric cross-linked peptide; D006710:Homocysteine; C007957:homocysteine thiolactone; D003541:Cystathionine beta-Synthase; D008239:Lysine
keywords: Col1A1; collagen modification; homocysteine thiolactone; hyperhomocysteinemia; pyridinoline cross-links