Cbfa1 Is a Positive Regulatory Factor in Chondrocyte Maturation*
- Hirayuki Enomoto‡,
- Motomi Enomoto-Iwamoto§,
- Masahiro Iwamoto¶,
- Shintaro Nomura‖,
- Miki Himeno‡,
- Yukihiko Kitamura‖,
- Tadamitsu Kishimoto‡ and
- Toshihisa Komori‡**‡
- From the ‡Department of Molecular Medicine,‖Department of Pathology, Osaka University Medical School, 2-2 Yamada-oka Suita, Osaka 565-0871, Japan, the§Department of Biochemistry and ¶Department of Oral Anatomy and Developmental Biology, Osaka University Faculty of Dentistry, 1-8 Yamada-oka, Suita, Osaka 565-0871, Japan, and **“Form and Function,” Precursory Research for Embryonic Science and Technology, Japan Science and Technology Corporation, Osaka 565-0871, Japan
Abstract
Cbfa1 is a transcription factor that belongs to the runt domain gene family. Cbfa1-deficient mice showed a complete lack of bone formation due to the maturational arrest of osteoblasts, demonstrating that Cbfa1 is an essential factor for osteoblast differentiation. Further, chondrocyte maturation was severely disturbed in Cbfa1-deficient mice. In this study, we examined the possibility that Cbfa1 is also involved in the regulation of chondrocyte differentiation. mRNAs for both Cbfa1 isotypes, type I Cbfa1 (Pebp2αA/Cbfa1) and type II Cbfa1 (Osf2/Cbfa1 or til-1), which are different in N-terminal domain, were expressed in terminal hypertrophic chondrocytes as well as osteoblasts. In addition, mRNA for type I Cbfa1 was expressed in other hypertrophic chondrocytes and prehypertrophic chondropcytes. In a chondrogenic cell line, ATDC5, the expression of type I Cbfa1 was elevated prior to differentiation to the hypertrophic phenotype, which is characterized by type X collagen expression. Treatment with antisense oligonucleotides for type I Cbfa1 severely reduced type X collagen expression in ATDC5 cells. Retrovirally forced expression of either type I or type II Cbfa1 in chick immature chondrocytes induced type X collagen and MMP13 expression, alkaline phosphatase activity, and extensive cartilage-matrix mineralization. These results indicate that Cbfa1 is an important regulatory factor in chondrocyte maturation.
Footnotes
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↵* This work was supported by grants from the Ministry of Education, Science and Culture, Japan, a Research Grant of the Princess Takamatsu Cancer Research Fund, the Naito Foundation, and the Ciba-Geigy Foundation for the Promotion of Science.The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
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↵‡ To whom all correspondence should be addressed: Dept. of Molecular Medicine, Osaka University Medical School, 2-2 Yamada-oka Suita, Osaka 565-0871, Japan. Tel.: 81-6-6879-7590; Fax: 81-6-6879-7796; E-mail: komorit@imed3.med.osaka-u.ac.jp.
- Abbreviations:
- GAPDH
-
glyceraldehyde-3-phosphate-dehydrogenase
- APase
-
alkaline phosphatase
- AS
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SE, and CS, antisense, sense, and control-scrambled, respectively
- Cbfa1
-
core-binding factor
- FBS
-
fetal bovine serum
- RT
-
reverse transcriptase
- PCR
-
polymerase chain reaction
- DMEM
-
Dulbecco's modified Eagle's medium
- S-oligos
-
phosphorothioate oligonucleotides
- bp
-
base pairs
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- Received August 10, 1999.
- Revision received December 1, 1999.
- The American Society for Biochemistry and Molecular Biology, Inc.
