Mechanism of Gli3 processing in Hedgehog signaling

Hedgehog 信号传导中 Gli3 的处理机制

• 批准号: 6781457
• 负责人: BAOLIN WANG
• 金额: $ 29.49万
• 依托单位: WEILL MEDICAL COLL OF CORNELL UNIV
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-05-01 至 2009-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6781457
• 关键词: DNA binding protein; biological signal transduction; biomarker; casein kinase; cell line; developmental genetics; fluorescence resonance energy transfer; laboratory mouse; phenotype; phosphorylation; proteasome; protein kinase A; protein protein interaction; protein structure function; site directed mutagenesis; transcription factor; western blottings

DESCRIPTION (provided by applicant): Cell-cell communication is a fundamental mechanism by which cell growth and differentiation are precisely controlled. Defects in these processes cause human cancer and birth defects. The Hedgehog (Hh) family of secreted signaling proteins controls cell growth and differentiation. Loss of or decrease in the Hh signaling pathway activity results in severe developmental birth defects. In addition to developmental abnormalities, inappropriate activation of the Hh signaling pathway is also associated with human cancers including basal cell carcinoma and medulloblastoma. Our long-term goal is to understand the molecular mechanisms by which Hh signal is transduced and to determine the role of Hh signaling in pattern specification and tumor formation. In Drosophila, Hh signal is mediated by Cubitus Interruptus (Ci), a zinc finger containing transcription factor. In the absence of Hh signal, a significant fraction of Ci protein is proteolytically processed to generate a transcription repressor. Hh signal stimulation blocks the Ci processing and activates the pathway. Ci processing requires its phosphorylation by PKA, CKI, and GSK3 and the activity of Slimb, a component of the novel class of ubiquitin ligase called SCF complex. Vertebrate homologs of Ci are Glil, Gli2, and Gli3. Many studies suggest that Gill and Gli2 act positively, whereas Gli3 plays a negative role in the pathway. Consistent with a negative role of Gli3 in the pathway, the majority of Gli3 protein is processed in the absence of Hh signaling. Hh signaling inhibits Gli3 processing and reduces its RNA levels, thus regulating the net output of Gli transcriptional activities. Molecular mechanisms of Gli3/Ci processing and its regulation by Hh signaling are largely unknown. Using a broadly-based approach that incorporates biochemical, cell biological, genetic, and pharmacological methods, the objectives of the proposed study are to 1) Elucidate the role of CKI and GSK3, and _TrCP, the vertebrate homolog of Slimb, in Gli3 processin.q; 2) Understand the role of the proteasome in Gli3 processin,q; 3) Determine the role of unprocessed and processed forms of Gli3 protein in vivo. The completion of the proposed study will significantly advance our understanding of the molecular mechanisms of the Hh signaling pathway. It may also shed light on the molecular mechanisms of human congenital syndromes caused by Gli3 mutations. In addition, this research may give us insights into the design of therapeutic agents that modulate Gli3 processin 9 to intervene or remedy cancer related to misregulation of the Hh signaling pathway.

描述（由申请人提供）：细胞 - 细胞通信是一种基本机制，可以通过其精确控制细胞生长和分化。这些过程中的缺陷会导致人类癌症和先天缺陷。分泌信号蛋白的刺猬（HH）家族控制细胞的生长和分化。 HH信号通路活动的丧失或减少会导致严重的发育出生缺陷。除了发育异常外，HH信号通路的不当激活还与包括基底细胞癌和髓母细胞瘤在内的人类癌症有关。我们的长期目标是了解转导HH信号的分子机制，并确定HH信号在模式规范和肿瘤形成中的作用。在果蝇中，HH信号由含有转录因子的锌指的Cubitus Intruptus（CI）介导。在没有HH信号的情况下，对CI蛋白的显着部分进行了蛋白水解处理以产生转录阻遏物。 HH信号刺激阻止了CI处理并激活途径。 CI处理需要PKA，CKI和GSK3的磷酸化以及SLIMB的活性，SLIMB是新型泛素连接酶的组成部分，称为SCF复合物。 CI的脊椎动物同源物是GLIL，GLI2和GLI3。许多研究表明，Gill和Gli2的起作用是积极的，而GLI3在途径中起负面作用。与GLI3在途径中的负作用一致，在没有HH信号传导的情况下，大多数GLI3蛋白都是处理的。 HH信号传导抑制GLI3处理并降低其RNA水平，从而调节GLI转录活性的净产量。 GLI3/CI处理的分子机制及其对HH信号传导的调节在很大程度上未知。使用一种基于广泛的方法，该方法结合了生物化学，细胞生物学，遗传和药理学方法，拟议研究的目标是1）阐明CKI和GSK3的作用，以及Slimb的脊椎动物同源物_trcp，在Gli3 ProcessIN.Q； 2）了解蛋白酶体在Gli3 Processin，Q中的作用； 3）确定体内gli3蛋白的未加工和加工形式的作用。拟议研究的完成将显着提高我们对HH信号通路分子机制的理解。它还可以阐明由GLI3突变引起的人类先天性综合征的分子机制。此外，这项研究可能会使我们深入了解治疗剂的设计，该治疗剂调节GLI3 Processin 9以干预或补救与HH信号通路不正常有关的癌症。