Expression of Type I, Type II, and Type X Collagen Genes during Altered Endochondral Ossification in the Femoral Epiphysis of Osteosclerotic (oc/oc) Mice

A. Yamasaki, M. Itabashi, Y. Sakai, H. Ito, Y. Ishiwari, H. Nagatsuka, N. Nagai

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

The osteosclerotic (oc/oc) mouse, a genetically distinct murine mutation that has a functional defect in its osteoclasts, also has rickets and shows an altered endochondral ossification in the epiphyseal growth plate. The disorder is morphologically characterized by an abnormal extension of hypertrophic cartilage at 10 days after birth, which is later (21 days after birth) incorporated into the metaphyseal woven bone without breakdown of the cartilage matrix following vascular invasion of chondrocyte lacunae. In situ hybridization revealed that the extending hypertrophic chondrocytes expressed type I and type II collagen mRNA, as well as that of type X collagen and that the osteoblasts in the metaphysis expressed type II and type X collagen mRNA, in addition to type I collagen mRNA. The topographic distribution of the signals suggests a possible co-expression of each collagen gene in the individual cells. Immunohistochemically, an overlapping deposition of type I, type II, and type X collagen was observed in both the extending cartilage and metaphyseal bony trabeculae. Such aberrant gene expression and synthesis of collagen indicate that pathologic ossification takes place in the epiphyseal/ metaphyseal junction of oc/oc mouse femur in different way than in normal endochondral ossification. This abnormality is probably not due to a developmental disorder in the epiphyseal plate but to the failure in conversion of cartilage into bone, since the epiphyseal plate otherwise appeared normal, showing orderly stratified zones with a proper expression of cartilage-specific genes.

Original languageEnglish
Pages (from-to)53-60
Number of pages8
JournalCalcified Tissue International
Volume68
Issue number1
DOIs
Publication statusPublished - Jan 2001

Keywords

  • Collagen synthesis
  • Endochondral ossification
  • Immunohistochemistry
  • In situ hybridization
  • Oc/oc mouse

ASJC Scopus subject areas

  • Endocrinology, Diabetes and Metabolism
  • Orthopedics and Sports Medicine
  • Endocrinology

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