Dissecting the Signaling Mechanisms of Smoothened

描述(由申请人提供)：Hedgehog(HH)信号转导通路在细胞发育过程中的图案化领域发挥着重要作用，在癌症中经常被激活。不适当的HH信号与基底细胞癌、髓母细胞瘤和横纹肌肉瘤有关，后者是人类最常见的癌症，髓母细胞瘤是儿童最常见的恶性脑肿瘤，横纹肌肉瘤的通路激活与预后不良相关。HH还与肺、乳腺和前列腺的零星肿瘤有关。因此，HH途径已成为一个有吸引力的治疗靶点；特异性抑制HH信号可能对这些癌症有效，而不会引发与传统化疗相关的不良副作用。为了设计和应用针对高血压的治疗方法，清楚地了解控制生理性高血压信号转导的调节机制和信号成分是至关重要的。因此，这项建议的目标是剖析控制HH途径诱导的机制事件，并识别促进下游信号转导的新效应器。我们将以果蝇黑腹果蝇为模型系统，通过对HH信号转导的分子和功能分析来实现这些目标。我们的研究主要集中在阐明HH途径的关键信号转导因子Smoothens的信号转导机制和下游效应。Smooth是G蛋白偶联受体超家族的一员。因此，本研究包括三个特定的目的，旨在更好地表征Smoothed GPCR信号活性：1)表征促进HH调节的Smoothed信号转导的细胞外GPCR结构特征；2)确定Smoothed中控制信号的GPCR功能结构域；3)定位Smoothed下游G蛋白效应器网络的功能。拟议中的研究将加强我们对HH信号是如何启动和传递的理解，并可能通过识别Smoothed和HH级联中的“压力点”来揭示新的治疗靶点。 与公共健康相关：Hedgehog(HH)信号转导通路在细胞发育过程中的图案化领域发挥着重要作用，在癌症中经常被激活。不适当的HH信号与基底细胞癌、髓母细胞瘤和横纹肌肉瘤有关，后者是人类最常见的癌症，髓母细胞瘤是儿童最常见的恶性脑肿瘤，横纹肌肉瘤的通路激活与预后不良相关。HH还与肺、乳腺和前列腺的零星肿瘤有关。因此，HH途径已成为一个有吸引力的治疗靶点；特异性抑制HH信号可能对这些癌症有效，而不会引发与传统化疗相关的不良副作用。为了设计和应用针对高血压的治疗方法，清楚地了解控制生理性高血压信号转导的调节机制和信号成分是至关重要的。因此，这项建议的目标是剖析控制HH途径诱导的机制事件，并识别促进下游信号转导的新效应器。我们将以果蝇黑腹果蝇为模型系统，通过对HH信号转导的分子和功能分析来实现这些目标。拟议中的研究将加强我们对HH信号是如何启动和传递的理解，并可能通过识别HH级联中的“压力点”来揭示新的治疗靶点。

DESCRIPTION (provided by applicant): The Hedgehog (Hh) signal transduction pathway plays an essential role in patterning fields of cells during development, and is frequently activated in cancer. Inappropriate Hh signaling is causative in basal cell carcinoma, the most common cancer in humans, medulloblastoma, the most common malignant brain tumor in children, and rhabdomyosarcoma, where pathway activation correlates with poor prognosis. Hh has also been implicated in sporadic tumors of the lung, breast and prostate. Consequently, the Hh pathway has emerged as an attractive therapeutic target; specific inhibition of Hh signaling will likely have efficacy against these cancers without triggering the undesirable side effects associated with conventional chemotherapy. To design and employ Hh-specific therapies, a clear understanding of the regulatory mechanisms and signaling components controlling physiological Hh signal transduction is of paramount importance. Accordingly, the goals of this proposal are to dissect mechanistic events governing Hh pathway induction and to identify novel effectors facilitating downstream signaling. We will achieve these goals through molecular and functional analysis of Hh signal transduction using the fruit fly Drosophila melanogaster as our model system. Our studies primarily focus on elucidating the signaling mechanisms and downstream effectors of Smoothened, the critical signal transducer of the Hh pathway. Smoothened is a member of the G-protein coupled receptor (GPCR) superfamily. As such, this study includes three Specific Aims designed to better characterize Smoothened GPCR signaling activity: 1) To characterize the extracellular GPCR structural features that facilitate Hh- regulated Smoothened signaling, 2) To identify GPCR functional domains in Smoothened that govern signaling and 3) To map the G-protein effector network functioning downstream of Smoothened. The proposed studies will enhance our understanding of how the Hh signal is initiated and transduced, and may reveal novel therapeutic targets through identifying "pressure points" on Smoothened and within the Hh cascade. PUBLIC HEALTH RELEVANCE: The Hedgehog (Hh) signal transduction pathway plays an essential role in patterning fields of cells during development, and is frequently activated in cancer. Inappropriate Hh signaling is causative in basal cell carcinoma, the most common cancer in humans, medulloblastoma, the most common malignant brain tumor in children, and rhabdomyosarcoma, where pathway activation correlates with poor prognosis. Hh has also been implicated in sporadic tumors of the lung, breast and prostate. Consequently, the Hh pathway has emerged as an attractive therapeutic target; specific inhibition of Hh signaling will likely have efficacy against these cancers without triggering the undesirable side effects associated with conventional chemotherapy. To design and employ Hh-specific therapies, a clear understanding of the regulatory mechanisms and signaling components controlling physiological Hh signal transduction is of paramount importance. Accordingly, the goals of this proposal are to dissect mechanistic events governing Hh pathway induction and to identify novel effectors facilitating downstream signaling. We will achieve these goals through molecular and functional analysis of Hh signal transduction using the fruit fly Drosophila melanogaster as our model system. The proposed studies will enhance our understanding of how the Hh signal is initiated and transduced, and may reveal novel therapeutic targets through identifying "pressure points" within the Hh cascade.