Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, MA 02215, USA.
Exp Cell Res. 2011 Nov 15;317(19):2711-8. doi: 10.1016/j.yexcr.2011.07.011. Epub 2011 Jul 23.
Contiguous regions along the mammalian gastrointestinal tract, from the esophagus to the rectum, serve distinct digestive functions. Some organs, such as the esophagus and glandular stomach or the small bowel and colon, are separated by sharp boundaries. The duodenal, jejunal and ileal segments of the small intestine, by contrast, have imprecise borders. Because human esophageal and gastric cancers frequently arise in a background of tissue metaplasia and some intestinal disorders are confined to discrete regions, it is useful to appreciate the molecular and cellular basis of boundary formation and preservation. Here we review the anatomy and determinants of boundaries and transitions in the alimentary canal with respect to tissue morphology, gene expression, and, especially, transcriptional control of epithelial identity. We discuss the evidence for established and candidate molecular mechanisms of boundary formation, including the solitary and combinatorial actions of tissue-restricted transcription factors. Although the understanding remains sparse, genetic studies in mice do provide insights into dominant mechanisms and point the way for future investigation.
哺乳动物胃肠道的连续区域，从食管到直肠，具有不同的消化功能。有些器官，如食管和胃腺或小肠和结肠，是由明显的边界隔开的。相比之下，小肠的十二指肠、空肠和回肠段则没有明确的边界。由于人类食管和胃癌经常发生在组织化生的背景下，而且一些肠道疾病局限于特定区域，因此了解边界形成和保持的分子和细胞基础是很有用的。在这里，我们回顾了消化道的解剖结构和边界及过渡的决定因素，涉及组织形态、基因表达，特别是上皮身份的转录控制。我们讨论了边界形成的既定和候选分子机制的证据，包括组织特异性转录因子的单一和组合作用。尽管理解仍然很少，但小鼠的遗传研究确实提供了对主要机制的深入了解，并为未来的研究指明了方向。
