Katada Tomohisa, Ito Motoaki, Kojima Yuki, Miyatani Seiji, Kinoshita Tsutomu
Developmental Biology, Department of Bioscience, School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda, Hyogo 669-1337, Japan.
Mech Dev. 2006 Nov;123(11):851-9. doi: 10.1016/j.mod.2006.08.001. Epub 2006 Aug 9.
Mastermind, which is a Notch signal component, is a nuclear protein and is thought to contribute to the transactivation of target genes. Previously we showed that XMam1, Xenopus Mastermind1, was essential in the transactivation of a Notch target gene, XESR-1, and was involved in primary neurogenesis. To examine the function of XMam1 during Xenopus early development in detail, XMam1-overexpressed embryos were analyzed. Overexpression of XMam1 ectopically caused the formation of a cell mass with pigmentation on the surface of embryos and expressed nrp-1. The nrp-1-positive cell mass was produced by XMam1 without expression of the Notch target gene, XESR-1, and not by the activation form of Notch, NICD. The ectopic expression of nrp-1 was not inhibited by co-injection of XMam1 with a molecule known to inhibit Notch signaling. The nrp-1 expression was also recognized in the animal cap injected with XMam1DeltaN, which lacks the basic domain necessary for interacting with NICD and Su(H). These results show that XMam1 has the ability to induce the cell fate into the neurogenic lineage in a Notch-independent manner.
Mastermind是Notch信号的一个组成部分，是一种核蛋白，被认为有助于靶基因的反式激活。此前我们发现，非洲爪蟾Mastermind1（XMam1）在Notch靶基因XESR-1的反式激活中必不可少，并参与初级神经发生。为了详细研究XMam1在非洲爪蟾早期发育过程中的功能，我们对过表达XMam1的胚胎进行了分析。XMam1的过表达异位导致胚胎表面形成有色素沉着的细胞团，并表达神经毡蛋白-1（nrp-1）。nrp-1阳性细胞团是由XMam1产生的，未表达Notch靶基因XESR-1，也不是由Notch的激活形式NICD产生的。将XMam1与一种已知可抑制Notch信号的分子共注射，并不会抑制nrp-1的异位表达。在注射了XMam1DeltaN的动物帽中也检测到了nrp-1的表达，XMam1DeltaN缺乏与NICD和Su(H)相互作用所需的碱性结构域。这些结果表明，XMam1具有以Notch非依赖方式将细胞命运诱导为神经源性谱系的能力。
