Basic helix-loop-helix protein DEC1 promotes chondrocyte differentiation at the early and terminal stages.
The mRNA level of basic helix-loop-helix transcription factor DEC1 (BHLHB2)/Stra13/Sharp2 was up-regulated during chondrocyte differentiation in cultures of ATDC5 cells and growth plate chondrocytes, and in growth plate cartilage in vivo. Forced expression of DEC1 in ATDC5 cells induced chondrogenic differentiation, and insulin increased this effect of DEC1 overexpression. Parathyroid hormone (PTH) and PTH-related peptide (PTHrP) suppressed DEC1 expression and the differentiation of ATDC5 cells, but DEC1 overexpression antagonized this inhibitory action of PTH/PTHrP. Transforming growth factor-beta or bone morphogenetic protein-2, as well as insulin, induced DEC1 expression in ATDC5 cultures where it induced chondrogenic differentiation. In pellet cultures of bone marrow mesenchymal stem cells exposed to transforming growth factor-beta and insulin, DEC1 was induced at the earliest stage of chondrocyte differentiation and also at the hypertrophic stage. Overexpression of DEC1 in the mesenchymal cells induced the mRNA expressions of type II collagen, Indian hedgehog, and Runx2, as well as cartilage matrix accumulation; overexpression of DEC1 in growth plate chondrocytes at the prehypertrophic stage increased the mRNA levels of Indian hedgehog, Runx2, and type X collagen, and also increased alkaline phosphatase activity and mineralization. To our knowledge, DEC1 is the first transcription factor that can promote both chondrogenic differentiation and terminal differentiation.
Shen
Ming
M
Department of Dental and Medical Biochemistry, Hiroshima University Graduate School of Biomedical Sciences, Hiroshima 734-8553, Japan.
Yoshida
Eri
E
Yan
Weiqun
W
Kawamoto
Takeshi
T
Suardita
Ketut
K
Koyano
Yasuhiko
Y
Fujimoto
Katsumi
K
Noshiro
Mitsuhide
M
Kato
Yukio
Y
D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins; D015152:Blotting, Northern; D015139:Blotting, Southern; D001854:Bone Marrow Cells / Q000378:metabolism; D002356:Cartilage / Q000378:metabolism; D002454:Cell Differentiation; D002455:Cell Division; D002460:Cell Line; D019902:Chondrocytes / Q000166:cytology* / Q000378:metabolism*; D024043:Collagen Type II / Q000378:metabolism; D024121:Collagen Type X / Q000378:metabolism; D050659:Core Binding Factor Alpha 1 Subunit; D018398:Homeodomain Proteins / Q000378:metabolism*; D006801:Humans; D008297:Male; D009363:Neoplasm Proteins; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D012333:RNA, Messenger / Q000378:metabolism; D011817:Rabbits; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014157:Transcription Factors / Q000378:metabolism; D014158:Transcription, Genetic; D014162:Transfection; D016212:Transforming Growth Factor beta / Q000378:metabolism*
D000469:Alkaline Phosphatase; D051792:Basic Helix-Loop-Helix Proteins; D024043:Collagen Type II; D024121:Collagen Type X; D050659:Core Binding Factor Alpha 1 Subunit; D018398:Homeodomain Proteins; D009363:Neoplasm Proteins; D012333:RNA, Messenger; D014157:Transcription Factors; D016212:Transforming Growth Factor beta; C107989:BHLHE40 protein, human