CTGF/Hcs24 interacts with the cytoskeletal protein actin in chondrocytes.
Connective tissue growth factor/hypertrophic chondrocyte-specific gene product 24 (CTGF/Hcs24) displays multiple functions in several types of mesenchymal cells, including the promotion of proliferation and differentiation of chondrocytes. Recently, the internalization and intracellular function of CTGF/Hcs24 were indicated as well. In this study, a binding protein for this factor was purified from the cytosolic fraction of human chondrosarcoma-derived chondrocytic cell line (HCS-2/8) by CTGF/Hcs24-affinity chromatography. The apparent molecular weight of the protein was 42kDa and determination of the internal amino acid sequence revealed this protein to be beta- or gamma-actin. An in vitro competitive binding assay of 125I-labeled recombinant CTGF/Hcs24 with cold-rCTGF/Hcs24 showed that the binding between actin and 125I-CTGF/Hcs24 was specific. Immunoprecipitation analysis also showed that CTGF/Hcs24 bound to actin in HCS-2/8 cells. However, rCTGF/Hcs24 had no effects on the expression level of gamma-actin mRNA or total actin protein. These findings suggest that a significant portion of intracellular CTGF/Hcs24 may regulate certain cell biological events in chondrocytes through the interaction with this particular cytoskeletal protein.
Yosimichi
Gen
G
Department of Biochemistry and Molecular Dentistry, Okayama University Graduate School of Medicine and Dentistry, 2-5-1 Shikata-cho, Okayama 700-8525, Japan.
Kubota
Satoshi
S
Hattori
Takako
T
Nishida
Takashi
T
Nawachi
Kumiko
K
Nakanishi
Tohru
T
Kamada
Masafumi
M
Takano-Yamamoto
Teruko
T
Takigawa
Masaharu
M
D000199:Actins / Q000378:metabolism*; D000595:Amino Acid Sequence; D001667:Binding, Competitive; D019902:Chondrocytes / Q000378:metabolism*; D055513:Connective Tissue Growth Factor; D003598:Cytoskeletal Proteins / Q000302:isolation & purification; D006801:Humans; D017874:Immediate-Early Proteins / Q000378:metabolism*; D036341:Intercellular Signaling Peptides and Proteins / Q000378:metabolism*; D008969:Molecular Sequence Data; D014407:Tumor Cells, Cultured
D000199:Actins; C526317:CCN2 protein, human; D003598:Cytoskeletal Proteins; D017874:Immediate-Early Proteins; D036341:Intercellular Signaling Peptides and Proteins; D055513:Connective Tissue Growth Factor