Delta-induced notch signaling mediated by RBP-J inhibits MyoD expression and myogenesis
Delta-induced notch signaling mediated by RBP-J inhibits MyoD expression and myogenesis
复制标题
DOI：
10.1074/jbc.274.11.7238
复制
发表时间：
1999-03-12
影响因子：
4.8
通讯作者：
Honjo, T
中科院分区：
文献类型：
--
作者：
Kuroda, K;Tani, S;Honjo, T
Notch受体及其配体Delta之间的相互作用所诱导的信号传导在脊椎动物以及无脊椎动物的细胞命运决定中起重要作用。脊椎动物Notch信号已经使用其组成型活性形式进行了研究，即截短的细胞内区域，其被认为通过与DNA结合蛋白RBP-J相互作用来模拟Notch-Delta信号。然而，由配体结合触发的Notch信号的分子机制尚不清楚，其导致分化的抑制。我们已经建立了一种骨髓瘤细胞系，其细胞表面表达小鼠Deltal，其可以通过与C2 C12肌肉祖细胞共培养来阻断肌肉分化。我们发现Delta诱导的Notch信号刺激了RBP-J结合基序的转录激活，该基序含有包括HES 1启动子在内的启动子。此外，配体诱导的Notch信号传导在1小时内上调HES 1 mRNA表达，随后降低MyoD mRNA的表达。由于放线菌酮处理不抑制HES 1 mRNA的诱导，因此HES 1启动子似乎是活化Notch的主要靶标。此外，RBP-J的转录活性形式，即VP 16-RBP-J，通过阻断MyoD蛋白的表达来抑制C2 C12细胞的肌肉分化。这些结果表明，通过Deltal/Notch信号传导的HES 1诱导由RBP-J介导，并通过随后抑制MyoD表达来阻断C2 C12细胞的肌源性分化。
Signaling induced by interaction between the receptor Notch and its ligand Delta plays an important role in cell fate determination in vertebrates as well as invertebrates. Vertebrate Notch signaling has been investigated using its constitutively active form, i.e. the truncated intracellular region which is believed to mimic Notch-Delta signaling by interaction with a DNA-binding protein RBP-J. However, the molecular mechanism for Notch signaling triggered by ligand binding, which leads to inhibition of differentiation, is not clear. We have established a myeloma cell line expressing mouse Deltal on its cell surface which can block muscle differentiation by co-culture with C2C12 muscle progenitor cells. We showed that Delta-induced Notch signaling stimulated transcriptional activation of RBP-J binding motif, containing promoters including the HES1 promoter. Furthermore, ligand-induced Notch signaling up-regulated HES1 mRNA expression within 1 h and subsequently reduced expression of MyoD mRNA, Since cycloheximide treatment did not inhibit induction of HES1 mRNA, the HES1 promoter appears to be a primary target of activated Notch. In addition, a transcriptionally active form of RBP-J, i.e. VP16-RBP-J, inhibited muscle differentiation of C2C12 cells by blocking the expression of MyoD protein. These results suggest that HES1 induction by the Deltal/Notch signaling is mediated by RBP-J and blocks myogenic differentiation of C2C12 cells by subsequent inhibition of MyoD expression.