Protein Kinase A and Intestinal Pseudo-obstruction

描述（由申请方提供）：慢性假性肠梗阻（CIP）是一种病因不均一的肠动力障碍，定义为“一种严重的致残性疾病，其特征为肠梗阻的反复发作或持续症状和体征，包括影像学记录的扩张肠伴气液水平，无固定的管腔闭塞病变”（Rudolph et al，1997）。在儿科CIP中，小肠扩张的模式可能因患者而异。在某些情况下，十二指肠和近端空肠受到特异性影响，而在其他情况下，回肠和近端结肠受到选择性影响。由于这种表现的变异性，很难确定CIP的病因和治疗。我们对CIP理解的最新进展来自于各种动物模型的使用。其中最突出的是针对小鼠的基因操作。本提案中描述的研究检查了一种新的CIP小鼠模型，该模型由发育中的神经嵴和成熟肠神经系统中的蛋白激酶A（PKA）抑制引起。在第一个具体目标中提出的实验将利用标准组织学和免疫组织化学方法来量化PKA抑制对神经元和神经胶质细胞数量的影响，并确定对肠神经元特定亚型的影响。在第二个具体目标中提出的实验将检验GDNF/Ret信号转导通路的抑制有助于所观察到的假性梗阻的分子病因学的假设。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，在没有已知原因的CIP病例中进行检查，并可能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.