Mechanisms of cell death and autophagy in intestinal epithelial cells in inflammation and cancer

总结 肠上皮细胞（Intestinalepithelialcells，IEC）是肠粘膜的重要屏障细胞，也是肠粘膜吸收的细胞工厂 和处理膳食营养素，以及防御分子的分泌和免疫系统的协调。 应答IEC正常功能的改变会导致炎症性肠病等病理变化 （IBD）。重要的是，IBD患者患结直肠癌（CRC）的风险增加，这是IBD的主要危险因素之一。 美国人群中最常见的肿瘤。最近的研究表明，潘氏细胞的关键作用， IEC存活控制功能障碍和肠道炎症的病因。因此，我们认为， 了解不同的信号级联如何控制肠道内稳态是一个基本问题， 具有IBD和CRC的潜在治疗意义的生物学。我们将在以下背景下讨论这些问题： 的PKCλ/1。我们的初步数据表明，在IEC中选择性失活PKCλ/ι导致了 潘氏细胞，引起肠道屏障的破坏，生态失调，肠道炎症和 增加肿瘤发生。重要的是，PKCλ/ι表达随着CD的进展而降低，并且它预测了CD的不良预后。 CRC中的生存。值得注意的是，这种潘氏细胞缺陷与隐窝凋亡、JNK活性和 PKCλ/1缺陷IEC中的自噬。我们的假设是PKCλ/ι是自噬的重要调节因子， 肠细胞稳态中的细胞死亡和炎症驱动的肿瘤发生。在本提案中，我们将讨论 以下基本问题：（1）PKCλ/i缺陷导致JNK激活在体内的作用是什么？ 增加肠上皮细胞凋亡和肠道炎症和肿瘤发生？(2)有哪些机制 从而PKCλ/1抑制JNK活性？(3)PKCλ/i缺陷的IEC中增强的自噬是存活的一个因素吗？ 在体内拮抗由PKCλ/1损失促进的JNK增加和细胞凋亡的机制， 预防肠道炎症和肿瘤发生？(4)PKCλ/ι抑制 自噬问题1和2将通过目标1中描述的实验来回答;问题3和4 将通过目标2中描述的实验来回答。这一提议将揭示一种新的模式， PKCλ/ι控制IEC凋亡和自噬及其在肠内稳态和炎症驱动中的作用 肿瘤发生，为新疗法开辟了可能性。

SUMMARY Intestinal epithelial cells (IECs) play an important role as barrier and as cellular factories in charge of absorbing and processing dietary nutrients, as well as the secretion of defense molecules and the orchestration of immune responses. Alterations in the normal function of IECs contribute to pathologies like inflammatory bowel diseases (IBD). Importantly, patients with IBD are at an increased risk for colorectal cancer (CRC), which is one of the most prevalent neoplasias among the US population. Recent studies have shown the critical role of Paneth cell dysfunction in controlling IEC survival and the etiopathogeneis of intestinal inflammation. Therefore, understanding how different signaling cascades control intestinal homeostasis is a fundamental question in biology with potential therapeutic implications for IBD and CRC. We will address these questions in the context of PKCλ/ι. Our preliminary data demonstrate that the selective inactivation of PKCλ/ι in IECs results in the loss of Paneth cells, which provokes the break of the intestinal barrier, dysbiosis, intestinal inflammation and increased tumorigenesis. Importantly, PKCλ/ι expression decreases with progression in CD and it predicts poor survival in CRC. Of note, this Paneth cell defect is associated with increased crypt apoptosis, JNK activity and autophagy in PKCλ/ι-deficient IECs. Our hypothesis is that PKCλ/ι is an essential regulator of autophagy and cell death in intestinal cell homeostasis and inflammation-driven tumorigenesis. In this proposal we will address the following fundamental questions: (1) What is the role in vivo of JNK activation by PKCλ/ι deficiency in increased apoptosis of IECs and intestinal inflammation and tumorigenesis? (2) What are the mechanisms whereby PKCλ/ι inhibits JNK activity? (3) Is enhanced autophagy in PKCλ/ι-deficient IECs a survival mechanism in vivo to antagonize the increased JNK and apoptosis promoted by the loss of PKCλ/ι and to prevent intestinal inflammation and tumorigenesis? (4) What are the mechanisms whereby PKCλ/ι represses autophagy? Questions 1 and 2 will be answered by the experiments described in Aim 1; and questions 3 and 4 will be answered by the experiments described in Aim 2. This proposal will unveil a new paradigm whereby PKCλ/ι controls IEC apoptosis and autophagy and their role in intestinal homeostasis and inflammation-driven tumorigenesis, opening possibilities for new therapies.