Schlafen mediation of intestinal adaptation

描述(申请人提供)：尽管进行了完全肠外营养(TPN)，但在饥饿或禁食患者中，粘膜萎缩通常会导致屏障功能障碍和败血症。此外，接受大量肠切除的MNY患者不能适应，必须维持永久性的TPN，死亡率高。目前旨在防止粘膜萎缩和增强适应的治疗方法疗效有限，可能是因为它们主要诱导增殖。我们认为，我们必须学会促进分化和增殖，以实现完整的功能粘膜，逆转粘膜萎缩，并产生最大的肠道适应。一些Schlafen家族蛋白以Schlafen和细胞特有的方式在某些细胞中调节细胞的生长、分化或发育。我们已经证明了啮齿动物蛋白Schlafen-3(Slfn3)是在肠道上皮细胞分化过程中被诱导的，并且在各种刺激下是必需的。我们的数据表明，SLFn3在体内随粘膜萎缩而变化，并促进分化，Schlafen-12(SLFN12)是其人类同源基因。我们假设Schlafen 3/12的诱导是肠细胞分化的基本和必要的共同途径，它可以被特异性地靶向促进分化和维持粘膜。我们进一步提出Schlafens 3/12伴随在细胞核上，在那里它们通过影响转录和依赖于CDX2同源框蛋白的正反馈机制来促进分化。我们将研究禁食TPN(萎缩)或Roux-en-Y胃旁路(肥大)后患者的肠粘膜，体外培养大鼠和人的肠上皮细胞，一种新的在体肠道上皮萎缩和肥大的啮齿动物模型，在体内感染病毒slfn3/slfn12，以及一种tet诱导的肠道特异的slfn3基因敲除小鼠，以实现以下特定目的：1)证明SLFN12介导人类肠细胞的分化，并反映粘膜萎缩或肥大的分化过程中slfn3的变化；2)确定slfn3和slfn12促进大鼠和人肠上皮细胞分化的机制。3)证明操纵SLFn3/SLFN12或核伴侣蛋白可在体内调节肠道萎缩/适应。这项研究将填补一个关键的知识空白，因为我们将描绘一个基本的机制，通过不同的刺激调节肠上皮细胞分化。这可能有助于对患有黏膜萎缩的饥饿或危重患者维持粘膜屏障的干预，并促进儿童或成人短肠综合征的营养。SLFn3基因敲除小鼠不仅将为我们将研究的趋同分化调控途径提供有价值的见解，还将为正常肠道发育、粘膜愈合和其他肠道疾病(如IBD)提供有价值的见解。此外，了解Schlafen蛋白如何促进分化将对其他上皮组织的分化和发育具有更广泛的意义。

DESCRIPTION (provided by applicant): Mucosal atrophy often leads to barrier failure and sepsis in starving or fasting patients in spite of total parenteral nutrition (TPN). In addition, mny patients who undergo massive bowel resection fail to adapt and must be maintained on permanent TPN with high mortality. Current therapies aimed at preventing mucosal atrophy and enhancing adaptation are limited in efficacy, perhaps because they mostly induce proliferation. We propose that we must learn to promote differentiation as well as proliferation to achieve an intact functional mucosa, reverse mucosal atrophy, and engender maximal intestinal adaptation. Some Schlafen-family proteins mediate cell growth, differentiation, or development in some cells in a Schlafen- and cell-specific fashion. We have demonstrated that the rodent protein Schlafen-3 (Slfn3) is induced during and required for intestinal epithelial differentiation in response to various stimuli. Our data indicate that Slfn3 varies with mucosal atrophy and promotes differentiation in vivo and that Schlafen-12 (SLFN12) is its human ortholog. We hypothesize that Schlafen 3/12 induction represents a fundamental and essential common pathway for enterocytic differentiation that can be specifically targeted to promote differentiation and maintain the mucosa. We further propose that Schlafens 3/12 are chaperoned to the nucleus where they enhance differentiation by affecting transcription and by a Cdx2 homeobox protein- dependent positive feedback mechanism. We will study intestinal mucosa in patients fasting on TPN (atrophy) or after Roux-en-Y gastric bypass (hypertrophy), rat and human intestinal epithelial cells in vitro, a novel rodent model of in vivo intestinal epithelial atrophy and hypertrophy, in vivo viral Slfn3/SLFN12 infection, and a tet-inducible intestine-specific Slfn3 knock-out mouse to achieve the following specific aims: 1) show that SLFN12 mediates human enterocytic differentiation and mirrors Slfn3 changes with differentiation in mucosal atrophy or hypertophy, 2) determine the mechanism by which Slfn3 and SLFN12 promote differentiation in rat and human intestinal epithelial cells, and 3) demonstrate that manipulating Slfn3/SLFN12 or a nuclear chaperone modulates intestinal atrophy/adaptation in vivo. This study will fill a critica knowledge gap because we will delineate a fundamental mechanism by which diverse stimuli regulate intestinal epithelial differentiation. This may facilitate interventions to maintain the mucosal barrier in starving or critically ill patients with mucosal atrophy and promote nutrition i pediatric or adult short bowel syndrome. The Slfn3 knock-out mouse will provide valuable insights not only into the convergent differentiation regulatory pathway we will study but also int normal gut development, mucosal healing and other intestinal disorders such as IBD. In addition, understanding how Schlafen proteins promote differentiation will have broader implications for differentiation and development in other epithelial tissues.