Enterocyte Apoptosis after Intestinal Resection

肠道适应是对大量小肠切除术（SBR）的一种关键的代偿反应， 其特征在于肠上皮细胞周转增加，如通过增殖和增殖的速率升高来衡量的。 凋亡细胞凋亡对适应程度的重要性在以前的研究中被揭示出来。 当细胞凋亡被积极抑制时，观察到这种赠款的资金周期作为放大的适应。 虽然SBR后细胞凋亡增加的机制目前尚不清楚，但我们已经确定， 这种反应受表皮生长因子受体（EGFR）信号传导调节， 促凋亡的Bcl-2家族成员Bax和转录因子信号转导子和激活子 转录（STAT）-1。作为这些关键观察的延伸，我们提出了一个全局假设， EGFR信号调节Bax的表达和活性以调节切除诱导的细胞凋亡。到 我们的目标是：1）确定STAT-1在Bax表达调控中的作用， 肠道适应STAT-1的表达和活性将在SBR后的回肠中以及 诱导凋亡后的细胞培养。STAT-1缺陷对Bax表达及细胞凋亡的影响 将测量细胞凋亡并研究Bax启动子上推定的STAT-1结合位点。（二） 确定p38 α丝裂原活化蛋白激酶（MARK）作为Bax活性调节剂的作用 在切除引起的适应过程中。p38表达/活性和Bax的时空分布 在小鼠和细胞凋亡的补充体外模型中记录SBR后的活化。的影响 将测定p38表达的条件性、精氨酸特异性缺失对Bax活性和细胞凋亡的影响 在SBR之后。3)确定EGFR调节Bax表达和活性的机制。的影响 将记录STAT-1和p38活化和表达的增强或破坏的EGFR信号传导。的 在EGFR抑制的情况下减弱STAT-1或p38表达对细胞凋亡和Bax的影响 将确定活性和表达。本申请中的拟议研究将确定 相关的信号通路直接细胞凋亡后大量SBR。深入了解 诱导细胞凋亡的机制是治疗靶点从实验室到床边转化的基础 旨在最大限度地刺激肠粘膜的再生，以响应大量的肠损失。

Intestinal adaptation is a critical, compensatory response to massive small bowel resection (SBR) and characterized by increased enterocyte turnover as gauged by elevated rates of both proliferation and apoptosis. The significance of apoptosis to the magnitude of adaptation was revealed during the previous funding cycle of this grant as amplified adaptation was observed when apoptosis was actively inhibited. While the mechanism(s) for elevated apoptosis after SBR is presently unknown, we have established that this response is regulated by epidermal growth factor receptor (EGFR) signaling and requires expression of the proapototic Bcl-2 family member Bax and the transcription factor signal transducer and activator of transcription (STAT)-1. As an extension of these key observations, we propose the global hypothesis that EGFR signaling modulates the expression and activity of Bax to regulate resection-induced apoptosis. To test this hypothesis our aims are: 1) Determine the role for STAT-1 in the regulation of Bax expression during intestinal adaptation. STAT-1 expression and activity will be determined in the ileum after SBR as well as in cell culture following induction of apoptosis. The effect of STAT-1 deficiency on Bax expression and apoptosis will be measured and putative STAT-1 binding sites on the Bax promoter will be investigated. 2) Determine the role for p38alpha mitogen-activated protein kinase (MARK) as a modulator of Bax activity during resection-induced adaptation. A temporal and spatial profile of p38 expression/activity and Bax activation will be recorded after SBR in mice and complementary in vitro models of apoptosis. The effect of conditional, intestine-specific deletion of p38 expression on Bax activity and apoptosis will be determined after SBR. 3) Determine the mechanism for EGFR regulation of Bax expression and activity. The effect of enhanced or disrupted EGFR signaling on STAT-1 and p38 activation and expression will be recorded. The effect of attenuated STAT-1 or p38 expression in the context of EGFR inhibition on apoptosis and Bax activity and expression will be determined. The proposed studies in this application will identify the most relevant signaling pathway to direct apoptosis after massive SBR. A thorough understanding of the precise mechanism for induction of apoptosis is fundamental for bench-to-bedside translation of therapeutic targets intended to maximally stimulate regrowth of the intestinal mucosa in response to massive intestinal loss.