Role of LIN28B in the regulation of intestinal epithelial growth

描述(由申请者提供)：通过在他的K01中建议的培训，我将继续我所需要的额外的指导和额外的研究时间，以增强我对肠道上皮生物学的热情。在这次获奖期间，我将有机会获得和完善成为一名发达科学家的基本技能。将通过每周与Rustgi博士举行两次会议、每年召开两次专家跨学科咨询委员会以及通过宾夕法尼亚大学、NIH和AGA利用职业和专业发展机会来促进职业发展。这些技能包括(但不限于)手稿和拨款准备，实验室会议报告，参加本文所述的研讨会和课程，以及在国际研究会议(DDW，Keystone)上的报告。培训还将包括生物统计学的课程工作(两个学期)、RNA生物学和基本生物信息学的短期课程、生物伦理学的持续培训、每周参加系列研讨会(在那里我 他将通过NIDDK P30消化和肝病分子研究中心及消化系召开每年两次的FLOO实验室会议，以及会见客座教授)、期刊俱乐部(半年一次的报告)和FLOO实验室会议。该项目的总体假设如下：Lin28b通过与c-myc的合作，在调节肠上皮细胞的生长和增殖方面发挥关键作用，在维持肠干细胞(ISC)方面发挥关键作用。将探索两种潜在的相互关联的机制：1)Lin28b结合与细胞生长相关的靶mRNAs，并与转录因子c-myc合作，c-myc是细胞生长的主要调节因子。2)Lin28b通过促进干细胞的识别和生长而影响ISC的维持。Lin28b通常在细胞分裂发生的肠道上皮隐窝中表达。Lin28b抑制了像let-7这样的miRNAs的成熟，它仅限于有丝分裂后分化细胞所在的绒毛上皮细胞。空间上的 限制LIN28b和let-7在肠上皮中的表达对于维持足够但有限的分化和增殖空间可能是至关重要的。C-MYC也局限于隐窝上皮，是上皮细胞增殖和生长所必需的。我们有证据支持Lin28b的let-7独立功能需要与c-myc密切合作。这一假设的具体目的如下：1)我们将在体外探索Lin28b和c-myc的功能关系。2)我们将通过对肠道上皮细胞中Lin28b的体内研究来评估Lin28b与c-myc的协同作用。3)我们将研究Lin28b对肠道干细胞隔室的调节作用。Lin28b功能可能与ISC动态平衡和上皮细胞增殖有关。确定Lin28b在肠隐窝中的功能可能会在调控上皮细胞增殖、分化和/或粘膜再生的细胞机制中提供重要的联系。 与公共卫生相关：该项目将探索干细胞和其他分裂细胞中肠道衬里细胞生长的调节。干细胞需要在人的整个一生中持续补充肠壁细胞。这项研究将为在疾病状态下如何维持、控制和干扰肠道细胞的生长提供关键的见解。

DESCRIPTION (provided by applicant): Through the proposed training in his K01, I will pursue the additional mentorship that I need and the additional research time to enhance my passion for intestinal epithelial biology. During this award period I will have the opportunity to acquire and refine fundamental skills of becoming a developed scientist. Career development will be fostered through twice-weekly meetings with Dr. Rustgi, convening an expert interdisciplinary advisory committee twice annually, and taking advantage of opportunities in career and professional development through UPenn, the NIH and the AGA. These skills include (but are not limited to) manuscript and grant preparation, lab meeting presentations, participation in the seminars and courses described herein, and presentations at international research conferences (DDW, Keystone). Training will also entail course-work in biostatistics (two semesters), short courses in RNA biology and basic bioinformatics, ongoing training in bioethics, weekly participation in the seminar series (where I will meet visiting professors), journal clubs (presentations semi-annually), and twice yearly floo lab meetings through the NIDDK P30 Center for Molecular Studies in Digestive and Liver Diseases and Division of Gastroenterology. The overarching hypothesis of this project is the following: LIN28B plays a critical role in regulating growth and proliferation in the intestinal epithelium via cooperation with c-MYC, with key roles for intestine stem cell (ISC) maintenance. Two potential interrelated mechanisms will be explored: 1) LIN28B binds to target mRNAs associated with cellular growth and cooperates with the transcription factor c-MYC, which is a master regulator of cell growth. and 2) LIN28B affects the maintenance of the ISC by promoting stem cell identity and growth. LIN28B is normally expressed in the intestinal epithelial crypt where cell division occurs. LIN28B represses the maturation of miRNAs such as Let-7, which is restricted to villus epithelium, where post- mitotic differentiated cells are located. The spatial restriction of LIN28B and Let-7 expression in the intestinal epithelium is likely crucial for maintaining sufficient but limited compartments of differentiation and proliferation. C-MYC is also restricted to the crypt epithelium and is required for epithelial proliferation and growth. W have evidence to support a Let-7-independent function of LIN28B entailing intimate cooperation with c-MYC. The Specific Aims of this proposal to test the hypothesis are the followin: 1) We will explore the functional relationship between LIN28B and c-MYC, in vitro. 2) We will assess how LIN28B cooperates with c-MYC through in vivo studies of Lin28b in the intestinal epithelium. 3) We will examine the potential of LIN28B to modulate the intestinal stem cell compartment. LIN28B function may be relevant to ISC homeostasis and epithelial proliferation. Determining how LIN28B functions in the intestinal crypt will likely provide an important link among the cellular mechanisms governing epithelial proliferation, differentiation, and/or mucosal regeneration. PUBLIC HEALTH RELEVANCE: This project will explore the regulation of cell growth in the lining of the intestine in stem cells and other dividing cells. Stem cells are required to constanly replenish cells of the intestinal lining throughout the entire life of an individual. This study wll provide key insights into how intestinal cell growth is maintained, controlled, and perturbed in disease states.