Protein Kinase A and Intestinal Pseudo-obstruction

描述（由申请人提供）：慢性假性肠梗阻（CIP）是一种异质性病因的肠道运动障碍，被定义为“一种严重的致残性障碍，其特征是反复发作或持续的肠梗阻症状和体征，包括在没有固定的管腔闭塞病变的情况下，影像学记录显示肠扩张伴气液水平”（Rudolph等，1997）。在小儿CIP中，小肠膨胀的模式可能因患者而异。在某些情况下，十二指肠和空肠近端受到特异性影响，而在其他情况下，回肠和结肠近端受到选择性影响。由于这种变异性的表现，这是极其困难的确定病因和治疗CIP。最近我们对CIP的理解的进展来自于使用各种动物模型。其中最突出的是针对小鼠的基因操作。本研究描述了一种新的小鼠CIP模型，该模型是由发育中的神经嵴和成熟的肠神经系统中蛋白激酶a （PKA）的抑制引起的。在第一个特定目标中提出的实验将使用标准的组织学和免疫组织化学方法来量化PKA抑制对神经元和胶质细胞数量的影响，并确定对特定肠道神经元亚型的影响。在第二个特定目标中提出的实验将验证GDNF/Ret信号转导通路的抑制有助于观察到的假性梗阻的分子病因的假设。这项研究将建立PKA信号转导通路的成员作为新的候选基因来检查病因不明的CIP病例，并有助于发现这种疾病的非手术治疗的新治疗靶点。

DESCRIPTION (provided by applicant): Chronic intestinal pseudo-obstruction (CIP) is an intestinal motility disorder of heterogeneous etiology that has been defined as "a severe, disabling disorder characterized by repetitive episodes or continuous symptoms and signs of bowel obstruction, including radiographic documentation of dilated bowel with air-fluid levels, in the absence of a fixed, lumen-occluding lesion" (Rudolph et al, 1997). In pediatric CIP the pattern of small bowel distention can vary from patient to patient. In some cases the duodenum and proximal jejunum are specifically affected, while in other cases the ileum and proximal colon are selectively affected. Because of this variability in presentation it is exceedingly difficult to identify the etiology of, and treat CIP. Recent advances in our understanding of the CIP have come from the use of various animal models. Most prominent among these have been targeted genetic manipulations in mice. The research described in this proposal examines a novel murine model of CIP that results from inhibition of protein kinase A (PKA) in the developing neural crest and mature enteric nervous system. The experiments proposed in the first specific aim will utilize standard histological and immunohistochemical methods to quantify effects of PKA inhibition on neuronal and glial cell number and identify effects on specific subtypes of enteric neurons. The experiments proposed in the second specific aim will test the hypothesis that inhibition of the GDNF/Ret signal transduction pathway contributes to the molecular etiology of the observed pseudo-obstruction. This research will establish members of the PKA signal transduction pathway as new candidate genes to examine in cases of CIP without a known cause and could contribute to the discovery of novel therapeutic targets for non-surgical treatment of this disease.