Spatio-temporal expression patterns of Runx2 isoforms in early skeletogenesis.
- Author:
Kang Young CHOI
1
;
Sang Won LEE
;
Mi Hyun PARK
;
Yong Chul BAE
;
Hong In SHIN
;
Soon Hyeun NAM
;
Young Jin KIM
;
Hyun Jung KIM
;
Hyun Mo RYOO
Author Information
1. Department of Biochemistry, School of Dentistry, Kyungpook National University, Daegu, Korea. hmryoo@knu.ac.kr
- Publication Type:Original Article ; Research Support, Non-U.S. Gov't
- Keywords:
chondrocytes;
chondrogenesis;
collagen type-II;
osteoblasts;
osteogenesis;
transcription factors
- MeSH:
Animals;
*Bone Development;
Cartilage/cytology/growth & development/metabolism;
Embryo and Fetal Development/genetics;
*Gene Expression Profiling;
*Gene Expression Regulation, Developmental;
In Situ Hybridization;
Mice;
Mice, Inbred ICR;
Protein Isoforms/genetics/metabolism;
Time Factors;
Transcription Factors/*genetics/metabolism
- From:Experimental & Molecular Medicine
2002;34(6):426-433
- CountryRepublic of Korea
- Language:English
-
Abstract:
Skeletogenesis occurs through either intramembranous or endochondral ossification. In addition, some parts of the skeletal components maintain their cartilaginous characteristics throughout life without mineralization. Runx2 is known to be a pivotal transcription factor for all skeletogenic processes. In this study, we examined the expression patterns of two major isoforms of Runx2 in early skeletogenesis. During intramembranous bone formation, Runx2-type I (Runx2-I) was widely expressed in osteoprogenitor cells and active osteoblasts, while Runx2-type II (Runx2-II) expression was stringently restricted to cells lining mineralized bones. Cells in permanent cartilage expressed collagen type II (Col-II) but never expressed Runx2 or Col-X. These permanent cartilages were well circumscribed by Runx2-I positive cells, in which Runx2-II was negative. In endochondral bone formation, Runx2 expression temporarily disappeared in Col-II-positive proliferating chondrocytes, but a secondary surge of Runx2-I expression occurred in the prehypertrophic zone before the mineralization of cartilage. Collectively, both Runx2 isoforms showed very similar expression patterns in active bone forming areas; however, Runx2-I has an exclusive role in the early commitment stage of intramembranous or endochondral bone forming processes or in cells surrounding permanent cartilage.
