Hedgehog Signaling in Photoreceptor Differentiation and Maintenance

描述(由申请人提供)：Hedgehog(HH)蛋白家族在决定神经细胞命运和维持成人神经干细胞潜力方面发挥着重要作用。先前的研究和我们的初步结果表明，Sonic Hedgehog(Shh)促进视网膜前体细胞的增殖，并影响早期出生的视网膜神经元的特性。然而，HH信号在哺乳动物光感受器细胞发育和存活中的确切作用尚不清楚。这项拟议的研究将使用分子遗传学方法来阐明HH信号在小鼠光感受器发育和维护中的作用。利用转基因小鼠品系和表达Cre重组酶的逆转录病毒进行Cre/loxP重组，可以消除必需的HH受体组分Smoothens(Smo)。我们将利用分子标记和电子显微镜分析干扰HH信号对出生后祖细胞增殖和细胞命运承诺的影响，以及对光感受器分化和形态发生的影响。HH信号在光感受器维持和存活中的作用将通过去除成熟视网膜中的Smo基因或Shh基因来表征，然后进行功能和形态分析。这项研究的结果将阐明哺乳动物光感受器分化和存活中一个重要的信号通路的功能。此外，这些研究将为光感受器退化的机制提供新的见解，并为开发抗击视网膜疾病的新疗法提供机会。 与公共健康相关：这项拟议的研究将研究一类重要的蛋白质--刺猬对感光细胞的形成和存活的影响，感光细胞在各种视网膜疾病中都会退化。这些研究的结果将增强我们保护光感受器细胞的能力，并指导神经干细胞向功能性光感受器细胞分化，用于视网膜疾病的治疗。

DESCRIPTION (provided by applicant): The Hedgehog (Hh) family of proteins plays important roles in the determination of neuronal cell fates and the maintenance of adult neural stem cell potentials. Previous studies and our preliminary results indicate that Sonic hedgehog (Shh) promotes retinal progenitor cell proliferation and affects specification of early born retinal neurons. However, the precise function of Hh signaling in mammalian photoreceptor cell development and survival is not well understood. The proposed research will use molecular genetic approaches to elucidate the roles of Hh signaling during mouse photoreceptor development and maintenance. The essential Hh receptor component Smoothened (Smo) will be eliminated by Cre/loxP recombination using transgenic mouse lines and retroviruses expressing Cre recombinase. The effects of disrupting Hh signaling on postnatal progenitor proliferation and cell fate commitment, and on photoreceptor differentiation and morphogenesis will be analyzed using molecular markers and electron microscopy. The roles of Hh signaling in photoreceptor maintenance and survival will be characterized by ablating the Smo gene or the Shh gene in the mature retina followed by functional and morphological analyses. Results of the proposed research will elucidate the function of an important signaling pathway in mammalian photoreceptor differentiation and survival. Moreover, these studies will provide new insights into mechanisms of photoreceptor degeneration and opportunities to develop novel therapies for combating retinal diseases. PUBLIC HEALTH RELEVANCE: The proposed research will study the influence of an important class of proteins called "hedgehog" on the formation and survival of photoreceptor cells, which undergo degeneration in various retinal diseases. The outcomes of these studies will enhance our abilities to protect photoreceptor cells and to direct the differentiation of neural stem cells towards functional photoreceptor cells for retinal disease therapy.