Yamaguchi A, Katagiri T, Ikeda T, Wozney J M, Rosen V, Wang E A, Kahn A J, Suda T, Yoshiki S
Department of Oral Pathology, School of Dentistry, Showa University, Tokyo, Japan.
J Cell Biol. 1991 May;113(3):681-7. doi: 10.1083/jcb.113.3.681.
The in vitro effect of recombinant human bone morphogenetic protein-2 (rhBMP-2) on osteogenic and myogenic differentiation was examined in two clonal cell lines of rat osteoblast-like cells at different differentiation stages, ROB-C26 (C26) and ROB-C20 (C20). The C26 is a potential osteoblast precursor cell line that is also capable of differentiating into muscle cells and adipocytes; the C20 is a more differentiated osteoblastic cell line. Proliferation was stimulated by rhBMP-2 in C26 cells, but inhibited in C20 cells. rhBMP-2 greatly increased alkaline phosphate (ALP) activity in C26 cells, but not in C20 cells. The steady-state level of ALP mRNA was also increased by rhBMP-2 in C26 cells, but not in C20 cells. Production of 3',5'-cAMP in response to parathyroid hormone (PTH) was dose-dependently enhanced by adding rhBMP-2 in both C26 and C20 cells, though the stimulatory effect was much greater in the former. There was neither basal expression of osteocalcin mRNA nor its protein synthesis in C26 cells, but they were strikingly induced by rhBMP-2 in the presence of 1 alpha,25-dihydroxyvitamin D3. rhBMP-2 induced no appreciable changes in procollagen mRNA levels of type I and type III in the two cell lines. Differentiation of C26 cells into myotubes was greatly inhibited by adding rhBMP-2. The inhibitory effect of rhBMP-2 on myogenic differentiation was also observed in clonal rat skeletal myoblasts (L6). Like BMP-2, TGF-beta 1 inhibited myogenic differentiation. However, unlike BMP-2, TGF-beta 1 decreased ALP activity in both C26 and C20 cells. TGF-beta 1 induced neither PTH responsiveness nor osteocalcin production in C26 cells, but it increased PTH responsiveness in C20 cells. These results clearly indicate that rhBMP-2 is involved, at least in vitro, not only in inducing differentiation of osteoblast precursor cells into more mature osteoblast-like cells, but also in inhibiting myogenic differentiation.
在大鼠成骨细胞样细胞的两个克隆细胞系ROB-C26（C26）和ROB-C20（C20）处于不同分化阶段时，检测了重组人骨形态发生蛋白-2（rhBMP-2）对成骨和成肌分化的体外作用。C26是一种潜在的成骨细胞前体细胞系，也能够分化为肌肉细胞和脂肪细胞；C20是一种分化程度更高的成骨细胞系。rhBMP-2刺激C26细胞增殖，但抑制C20细胞增殖。rhBMP-2显著增加C26细胞中的碱性磷酸酶（ALP）活性，但对C20细胞无此作用。rhBMP-2也使C26细胞中ALP mRNA的稳态水平升高，但对C20细胞无此作用。在C26和C20细胞中添加rhBMP-2均剂量依赖性增强了对甲状旁腺激素（PTH）的3',5'-环磷酸腺苷（cAMP）生成反应，不过前者的刺激作用更强。C26细胞中骨钙素mRNA既无基础表达，也无蛋白合成，但在1α,25-二羟基维生素D3存在的情况下，rhBMP-2可显著诱导其表达。rhBMP-2未引起这两种细胞系中I型和III型前胶原mRNA水平的明显变化。添加rhBMP-2可显著抑制C26细胞向肌管的分化。在克隆大鼠骨骼肌成肌细胞（L6）中也观察到rhBMP-2对成肌分化的抑制作用。与BMP-2一样，转化生长因子-β1（TGF-β1）也抑制成肌分化。然而，与BMP-2不同的是，TGF-β1降低了C26和C20细胞中的ALP活性。TGF-β1既未诱导C26细胞产生PTH反应性，也未诱导其产生骨钙素，但增加了C20细胞中的PTH反应性。这些结果清楚地表明，至少在体外，rhBMP-2不仅参与诱导成骨细胞前体细胞分化为更成熟的成骨细胞样细胞，还参与抑制成肌分化。
