成骨不全
斑马鱼
Ⅰ型胶原
胶原蛋白,I型,α1
化学
解剖
N-末端末端肽
羟基化
结缔组织
细胞外基质
细胞生物学
内分泌学
病理
生物
内科学
遗传学
医学
生物化学
基因
碱性磷酸酶
酶
骨钙素
作者
Charlotte Gistelinck,P. Eckhard Witten,Ann Huysseune,Sofie Symoens,Fransiska Malfait,Daria Larionova,Pascal Simoens,Manuel Dierick,Luc Van Hoorebeke,Anne De Paepe,Ronald Y. Kwon,MaryAnn Weis,David R. Eyre,Andy Willaert,Paul Coucke
摘要
Bruck syndrome (BS) is a disorder characterized by joint flexion contractures and skeletal dysplasia that shows strong clinical overlap with the brittle bone disease osteogenesis imperfecta (OI). BS is caused by biallelic mutations in either the FKBP10 or the PLOD2 gene. PLOD2 encodes the lysyl hydroxylase 2 (LH2) enzyme, which is responsible for the hydroxylation of lysine residues in fibrillar collagen telopeptides. This hydroxylation directs crosslinking of collagen fibrils in the extracellular matrix, which is necessary to provide stability and tensile integrity to the collagen fibrils. To further elucidate the function of LH2 in vertebrate skeletal development, we created a zebrafish model harboring a homozygous plod2 nonsense mutation resulting in reduced telopeptide hydroxylation and crosslinking of bone type I collagen. Adult plod2 mutants present with a shortened body axis and severe skeletal abnormalities with evidence of bone fragility and fractures. The vertebral column of plod2 mutants is short and scoliotic with compressed vertebrae that show excessive bone formation at the vertebral end plates, and increased tissue mineral density in the vertebral centra. The muscle fibers of mutant zebrafish have a reduced diameter near the horizontal myoseptum. The endomysium, a layer of connective tissue ensheathing the individual muscle fibers, is enlarged. Transmission electron microscopy of mutant vertebral bone shows type I collagen fibrils that are less organized with loss of the typical plywood-like structure. In conclusion, plod2 mutant zebrafish show molecular and tissue abnormalities in the musculoskeletal system that are concordant with clinical findings in BS patients. Therefore, the plod2 zebrafish mutant is a promising model for the elucidation of the underlying pathogenetic mechanisms leading to BS and the development of novel therapeutic avenues in this syndrome. © 2016 American Society for Bone and Mineral Research.
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