title: Alterations of collagen matrix in weight-bearing bones during skeletal unloading.
abstract: Skeletal unloading induces loss of bone mineral density in weight-bearing bones. The objectives of this study were to characterize the post-translational modifications of collagen of weight-bearing bones subjected to hindlimb unloading for 8 weeks. In unloaded bones, tibiae and femurs, while the overall amino acid composition was essentially identical in the unloaded and control tibiae and femurs, the collagen cross-link profile showed significant differences. Two major reducible cross-links (analyzed as dihydroxylysinonorleucine and hydroxylysinonorleucine) were increased in the unloaded bones. In addition, the ratios of the former to the latter as well as pyridinoline to deoxypyridinoline were significantly decreased in the unloaded bones indicating a difference in the extent of lysine hydroxylation at the cross-linking sites between these two groups. These results indicate that upon skeletal unloading the relative pool of newly synthesized collagen is increased and it is post-translationally altered. The alteration could be associated with impaired osteoblastic differentiation induced by skeletal unloading that results in a mineralization defect.
authors.affiliation: Dental Research Center, University of North Carolina, Chapel Hill 27599-7455, USA.
authors.forename: M
authors.initials: M
authors.lastname: Shiiba
authors.forename: S B
authors.initials: SB
authors.lastname: Arnaud
authors.forename: H
authors.initials: H
authors.lastname: Tanzawa
authors.forename: K
authors.initials: K
authors.lastname: Uzawa
authors.forename: M
authors.initials: M
authors.lastname: Yamauchi
mesh_terms: D000596:Amino Acids / Q000032:analysis / Q000378:metabolism; D000818:Animals; D001835:Body Weight; D001857:Bone Matrix / Q000378:metabolism*; D001842:Bone and Bones / Q000378:metabolism*; D003094:Collagen / Q000737:chemistry / Q000378:metabolism*; D019417:Hindlimb Suspension; D006900:Hydroxylation; D008239:Lysine / Q000378:metabolism; D008297:Male; D011392:Proline / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D016474:Weight-Bearing
chemical_list: D000596:Amino Acids; C015484:pyridinoline; C036020:deoxypyridinoline; D003094:Collagen; D011392:Proline; D008239:Lysine