Mouse models of Pik3ca brain overgrowth disorders

项目总结 这项建议概述了一系列全面的实验，以评估过度生长表型的基础。 以小鼠为模型系统，与PIK3CA中功能突变的获得相关。虽然很好 在癌症研究中，最近的数据揭示了PIK3CA突变在几种发育障碍中的作用 包括MCAP、DMEG、丁香综合征、表皮痣和脂溢性角化病。这里将评估 3种不同的PIK3CA功能突变导致的发育和信号通路中断， 特别强调发展中的大脑。到目前为止，所有报道的PIK3CA突变都是合子后突变或嵌合体突变 而不是生殖系突变。因此，我们假设PIK3CA表型与 突变的严重程度和嵌合体的水平(和分布)。为了检验这一假设和其他假设，我们将 使用标准条件遗传学方法在胚胎中表达3个患者相关的PIK3CA GOF突变 中枢神经系统神经前体细胞及其后代。然后我们将产生ES细胞嵌合体，注入ES细胞 在野生型囊胚中组成性表达相同的突变以评估表型嵌合体 大脑内部和整个身体的关系。我们还建议在子宫内使用 电穿孔技术可以更准确地将马赛克表达靶向发育中的大脑。我们的研究 将评估大脑病理的发育性发病机制并表征相关的癫痫，a 按临床相关表型。最后，我们将使用药理学方法来评估 导致出生后小鼠急性依赖PIK3CA发作的潜在机制。这些化验结果代表 在PIK3CA节段性脑过度生长中开发分子理性癫痫治疗的第一步 综合症患者。

PROJECT SUMMARY This proposal outlines a comprehensive series of experiments to assess the basis of overgrowth phenotypes associated with gain of function mutations in PIK3CA, using the mouse as a model system. Although well studied in cancer, recent data has revealed a role for PIK3CA mutation in several developmental disorders including MCAP, DMEG, CLOVES syndrome, epidermal nevi and seborrheic keratosis. Here will assess the developmental and signaling pathway disruptions caused by 3 different Pik3ca gain of function mutations, with particular emphasis on the developing brain. To date, all reported PIK3CA mutations are postzygotic or mosaic rather than germline mutations. Accordingly, we hypothesize that PIK3CA phenotypes correlate with both the severity of the mutation and level (and distribution) of mosaicism. To test this and other hypotheses, we will use standard conditional genetic approaches to express 3 patient-related Pik3ca gof mutations in embryonic CNS neuronal progenitors and their descendants. We will then generate ES cell chimeras, injecting ES cells constitutively expressing the same mutations into wild-type blastocysts to assess phenotype-mosaicism relationships both within the brain and throughout the entire body. We also propose to use in utero electroporation technology to more specifically target mosaic expression to the developing brain. Our studies will assess the developmental pathogenesis of brain pathology and characterize the associated epilepsy, a pressing clinically relevant phenotype. Finally, we will use pharmacological approaches to assess the underlying mechanisms driving acutely Pik3ca-dependent seizures in post-natal mice. These assays represent the first step toward developing molecularly rational epilepsy therapy in PIK3CA segmental brain overgrowth syndrome patients.