Mechanisms of Gastrointestinal Epithelial Cell Injury & Repair During Development

由于发育不成熟，早产儿面临着许多独特的问题。其中最 毁灭性的是坏死性小肠结肠炎(NEC)，在美国，每年每10万名活产儿中就有12名婴儿死亡 幸存者经常会出现严重的喂养问题、肝功能衰竭和神经发育障碍。 了解肠道发育过程中的损伤和修复机制是开发新的肠道的关键 NEC的预防和治疗策略。这项建议将研究胃肠道疾病的机制。 通过检验早产儿肠道在发育过程中的上皮细胞损伤和修复 婴儿和新生小鼠更容易受到肿瘤坏死因子的损伤，因为个体发育正常 EGFR的表达和活性降低。这一假设将通过以下具体的 目的：1)明确不同发育阶段肿瘤坏死因子在肠道损伤和细胞凋亡中的作用。这将是 使用早期肠道损伤的组织病理损伤评分以及免疫荧光来完成 2)检测肿瘤坏死因子对新生儿表皮生长因子受体抑制的影响 与成年人相比。我们将研究肿瘤坏死因子对多个EGFR磷酸化位点和下游的影响 靶点，以及EGFR内化在肿瘤坏死因子刺激的EGFR抑制中的作用。这一目标将被用来 免疫荧光和免疫印迹分析研究EGFR激活的下游靶点；3) 从药理学和遗传学角度确定EGFR激活在保护肿瘤坏死因子诱导的损伤中的作用 EGFR激活的模型。这个目标将建立在目标1和目标2中开发的技术的基础上，并将其应用于小鼠 具有结构性活性的EGFR，具有药理活性的EGFR，以及缺乏EGFR。总体而言，这些研究 将揭示TNF和EGFR在肠道组织发育过程中的损伤过程中的作用，并将 确定潜在的治疗和化学预防的新途径。除上述研究外，这项建议 将通过细胞生物学、发育生物学和 统计；通过提供强大实验室的指导；通过独特地利用强大的资源 可在Vanderbilt获得，以促进对胃肠道疾病的独立研究。

Premature infants face a host of unique issues due to their developmental immaturity. One of the most devastating is necrotizing enterocolitis (NEC), which yearly kills 12 babies per 100,000 live births in the USand frequently leaves survivors with severe feeding issues, liver failure, and neurodevelopmental disability. Understanding mechanisms of intestinal injury and repair in developing intestine is key to developing new prevention and therapeutic strategies for NEC. This proposal will investigate the mechanisms of gastrointestinal epithelial cell injury and repair duringdevelopment by testing the hypothesis that the intestine of premature infants and newborn mice is more susceptible to TNF-induced injury because of an ontogenically normal decrease in expression and activation of EGFR. This hypothesis will be examined through the following specific Aims: 1) Define the effects of TNF on intestinal injury and apoptosis at different developmental stages. This will be accomplished using histopathologic injury scores of early intestinal damage as well as immunofluorescence and immunohistochemicalassays for apoptosis; 2) Determine the effects of TNF on EGFR inhibition in neonates compared to adults. We will study the effects of TNFon multipleEGFR phosphorylation sites and down-stream targets, and the role of EGFR internalization in TNF-stimulatedEGFR inhibition. This aim willutilize immunofluorescence and western blot analysis to study the down-stream targets of EGFR activation; and 3) Determine the role of EGFR activation in protecting against TNFinduced injury using pharmacologic and genetic models of EGFR activation. This aim will build on techniques developed in Aim 1 and 2 and apply them to mice with constitutively active EGFR, pharmacologicallyactive EGFR, and deficiency of EGFR. Overall,these studies will reveal the roles of TNFand EGFR in intestinal injury processes in developing intestinal tissue, and will identify potential novel avenues oftherapy and chemoprevention. In addition to the above studies, this proposal will greatly enhance career development through didactic training in cell biology, developmental biology, and statistics; by providing mentoring from a strong laboratory; and by utilizing the strong resources uniquely available at Vanderbilt to foster independent investigation in gastrointestinal disease.