Yang Ruyan, Bie Wenjun, Haegebarth Andrea, Tyner Angela L
Department of Biochemistry and Molecular Genetics, University of Illinois at Chicago, Chicago, Illinois, USA.
Cell Cycle. 2006 Jan;5(2):180-3. doi: 10.4161/cc.5.2.2306. Epub 2006 Jan 16.
The intestinal epithelium undergoes continuous rapid renewal throughout adult life. To examine contributions of D-type cyclins to proliferation in the intestine, we examined D-type cyclin expression in the mouse proximal and distal small intestine and colon. Cyclin D1 was expressed throughout the small and large intestine. In contrast, cyclin D2 and D3 protein levels were not readily detectable in the duodenum. Levels of RNAs encoding all three D-type cyclins were higher in the ileum and colon than in the duodenum. Immunohistochemistry revealed that cyclin D1 and D2 are expressed in colonic epithelial cells, with cyclin D2 being more restricted to the proliferative zone. Expression of cyclinD1 and D2 was detected in conditionally immortalized young adult mouse colon (YAMC) cells and in a colon epithelial cell line derived from the Apc(Min/+) mouse (IMCE cells), with higher basal levels of both cyclins in the IMCE cells. In an experimental model of colitis, levels of cyclin D1 mRNA increased significantly, and cyclin D1 protein was localized to both epithelial cells and inflammatory cells in the colon. The individual D-type cyclins may make different contributions to proliferation, disease and development of cancer in the intestine.
成年期肠道上皮细胞持续快速更新。为了研究D型细胞周期蛋白对肠道增殖的作用，我们检测了小鼠近端和远端小肠以及结肠中D型细胞周期蛋白的表达。细胞周期蛋白D1在整个小肠和大肠中均有表达。相比之下，在十二指肠中不易检测到细胞周期蛋白D2和D3的蛋白水平。编码所有三种D型细胞周期蛋白的RNA水平在回肠和结肠中高于十二指肠。免疫组织化学显示，细胞周期蛋白D1和D2在结肠上皮细胞中表达，其中细胞周期蛋白D2更局限于增殖区。在条件性永生化的成年幼鼠结肠（YAMC）细胞和源自Apc(Min/+)小鼠的结肠上皮细胞系（IMCE细胞）中检测到细胞周期蛋白D1和D2的表达，IMCE细胞中这两种细胞周期蛋白的基础水平更高。在结肠炎实验模型中，细胞周期蛋白D1 mRNA水平显著升高，且细胞周期蛋白D1蛋白定位于结肠的上皮细胞和炎性细胞。单个D型细胞周期蛋白可能对肠道的增殖、疾病和癌症发展有不同作用。
