Koo Bon-Kyoung, Lim Hyoung-Soo, Chang Hee Jin, Yoon Mi-Jeong, Choi Yongwook, Kong Myung-Phil, Kim Cheol-Hee, Kim Jin-Man, Park Jae-Gahb, Kong Young-Yun
Department of Biological Sciences, Seoul National University, Silim-dong, Gwanak-gu, Seoul, South Korea.
Gastroenterology. 2009 Jul;137(1):145-55, 155.e1-3. doi: 10.1053/j.gastro.2009.03.046. Epub 2009 Mar 28.
BACKGROUND & AIMS: The intestinal epithelium consists of EphB2-positive proliferative basal cryptic cells and EphrinB1-positive, postmitotic differentiated cells. We investigated the effects of Notch signaling on formation of the EphB2-EphrinB1 boundary using mouse and tissue culture models.
We created mice in which Mind bomb-1 (Mib1), an essential E3 ubiquitin ligase that activates Notch ligands, was inactivated specifically in the intestinal epithelia (Vil-Cre;Mib1(f/f)); Notch is, therefore, inactivated in this tissue. We also studied the effects of different inhibitors on intestinal epithelial cells (IEC-6) that express activated Notch. Tissues and cells were analyzed by immunohistochemical and immunoblot analyses.
The intestinal epithelia of Vil-Cre;Mib1(f/f) mice had reduced numbers of EphrinB1-positive cells, compared with controls, but increases in EphB2-positive cells; beta-catenin was activated in these cells. These phenotypes were reversed by expression of a constitutively active form of Notch1. In the IEC-6 cells, Notch signaling activated the expression of EphrinB1 in an Hes1-independent manner, but down-regulated the expression of EphB2 through the GSK3beta-mediated inhibition of beta-catenin.
Notch signaling regulates formation of the EphB2-EphrinB1 boundary in the mouse intestinal epithelium.
肠上皮由EphB2阳性的增殖性隐窝基底细胞和EphrinB1阳性的有丝分裂后分化细胞组成。我们使用小鼠和组织培养模型研究了Notch信号通路对EphB2-EphrinB1边界形成的影响。
我们构建了在肠上皮细胞中特异性使激活Notch配体的必需E3泛素连接酶Mind bomb-1（Mib1）失活的小鼠（Vil-Cre;Mib1(f/f)）；因此，Notch在该组织中失活。我们还研究了不同抑制剂对表达激活型Notch的肠上皮细胞（IEC-6）的影响。通过免疫组织化学和免疫印迹分析对组织和细胞进行分析。
与对照相比，Vil-Cre;Mib1(f/f)小鼠的肠上皮中EphrinB1阳性细胞数量减少，但EphB2阳性细胞数量增加；β-连环蛋白在这些细胞中被激活。这些表型通过表达组成型活性形式的Notch1而逆转。在IEC-6细胞中，Notch信号通路以不依赖Hes1的方式激活EphrinB1的表达，但通过GSK3β介导的对β-连环蛋白的抑制下调EphB2的表达。
Notch信号通路调节小鼠肠上皮中EphB2-EphrinB1边界的形成。
