Mechanisms of gastrointestinal cell responses to Notch Signaling

描述（由申请人提供）：我对了解正常发育与疾病机制之间的关系感兴趣。因此，作为研究生，我在分子生物学、生物化学和发育遗传学方面打下了坚实的基础。作为博士后，我利用消化道作为模型系统，研究了胚胎和成年小鼠干细胞更新和分化的基本发育问题。Notch信号在这些过程中起着关键作用。利用强大的小鼠遗传工具，我已经证明了Notch信号及其关键下游肠道限制性转录因子Atoh1在肠道干细胞和祖细胞增殖、去分化和癌症中的作用，并发表了4篇第一作者论文。为了进一步了解胃肠道细胞对上皮细胞中Notch信号的反应机制，我现在的目标是研究Notch信号下游的转录因子。为了系统地识别在肠细胞分化中发挥重要作用的新型转录因子，研究其潜在的转录机制，我将学习和应用染色质免疫沉淀结合高通量DNA测序（ChIP-Seq）的全基因组新方法。我将分析分泌转录因子Atoh1和Tcf4的全基因组结合，并测试它们在细胞复制和肠分泌细胞系分化中的相互作用的特定机制假设。在不表达关键下游因子Atoh1的胃中，我将验证一个新的假设，即胃限制同源物Ascl1在Notch信号的下游作用，调节上皮细胞增殖和肠内分泌分化。因此，我所提出的研究将为胃肠道上皮分化的中心机制提供新颖而重要的见解，并有助于阐明其分子机制

DESCRIPTION (provided by applicant): I am interested in understanding the relationship between normal development and mechanisms of disease. I therefore built a strong foundation in molecular biology, biochemistry and developmental genetics as a graduate student. As a postdoctoral fellow, I have used the digestive tract as a model system to study fundamental developmental questions of stem cell renewal and differentiation in fetal and adult mice. Notch signaling plays critical roles in these processes. Using powerful mouse genetic tools, I have demonstrated roles for Notch signaling and its key downstream intestine-restricted transcription factor Atoh1 in gut stem and progenitor cell proliferation, dedifferentiation and cancer, leading t 4 first-author publications. To further understand mechanisms of gastrointestinal cell response to Notch signaling in epithelial cells, I now aim to investigate transcription factors that act downstream of Notch signaling. To systemically identify novel transcription factors that play important roles in intestinal cell differentiation and study the underlying transcriptional mechanisms, I will learn and apply the new genome-wide approach of chromatin immunoprecipitation coupled with high-throughput DNA sequencing (ChIP-Seq). I will analyze genome-wide binding of the secretory transcription factors Atoh1 and Tcf4, and test specific mechanistic hypotheses regarding their interactions in cell replication and in differentiation of te intestinal secretory cell lineage. In the stomach, which does not express the crucial downstream factor Atoh1, I will test the novel hypothesis that a stomach-restricted homologue, Ascl1, acts downstream of Notch signaling to regulate epithelial cell proliferation and enteroendocrine differentiation. The studies I propose will hence provide novel and significant insights into central mechanisms of gastrointestinal epithelial differentiation and help illuminate the molecular basis of diseases ranging from congenital disorders and inflammation to cancer. I aim to become an independent principal investigator in the area of gastrointestinal biology, with expertise in lineage differentiation. A K99/R00 award will facilitate my transition to full independence through sequential mentored and independent phases. In the short-term, this award will allow me to learn new technologies including ChIP-Seq and bioinformatics analysis, hence broadening my expertise to include knowledge of systems biology and genomics, under the mentorship of Ramesh Shivdasani. His lab has successfully completed projects and published important papers that apply such approaches, providing a perfect training environment. Furthermore, the exceptional institutional environment at the Dana-Farber Cancer Institute and Harvard Medical School will further enable my transition to independence by providing institutional programs, facilities, opportunities for collaboration, and broad mentorship My mentorship committee includes world-leading Harvard faculty in the fields of gastrointestinal biology, transcription and genomics to provide guidance and support towards developing my own research program. Furthermore, the Harvard Stem Cell Institute and the Center for Functional Cancer Epigenetics (CFCE) at Dana-Farber Cancer institute will not only give me outstanding opportunities to refine my methods but will also allow me to interact and collaborate with eminent scientists in stem cell biology and epigenomics. Thus, a K99/R00 award will provide critical support at a crucial stage in my career and permit me to make a long-term commitment toward studying the unique biology that underlies gastrointestinal diseases. In the long-term future as a successful independent investigator, I will devote myself to understanding basic mechanisms of gastrointestinal diseases, leading collaborative efforts with clinical and computational biologists, and educating the next generation of basic and clinical scientists.