Regulation of JNK Signaling in Epidermal Morphogenesis

描述（由申请人提供）：细胞的命运取决于其感知和适当响应环境的能力。Jun激酶（JNK）信号转导通路响应于多种发育和环境信号而被激活以控制基本细胞行为，例如增殖、分化、形态发生和凋亡，但是调节对特定信号的适当响应的机制知之甚少。人类JNK信号传导的不适当激活可导致许多疾病，包括慢性炎症、癌症和代谢疾病，而在发育早期JNK信号传导的丧失导致小鼠的出生缺陷。这个建议的总体目标是了解JNK信号是如何调节，以产生适当的反应，在动物的发展和稳态。调节适当响应的一种方法是使用不同信号下游的信号换能器的独特组合。在果蝇中的某些JNK依赖性过程中被选择性激活的候选转导子是混合谱系激酶（MLK），其由滑动（slpr）基因座编码。SLPR/MLK是组织形态发生的重要和特异性调节因子，其在JNK激酶激酶（JNKKK）水平上起作用以刺激JNK依赖的组织重组。为了研究SLPR/MLK调节JNK信号传导和组织组织结构的分子机制，我们提出了以下具体目标：（1）使用slpr突变动物的表型分析，结合突变、缺失和嵌合JNKKK转基因的表达来表征SLPR的基本功能结构域。(2)通过遗传筛选修饰与SLPR功能丧失相关的缺陷的蛋白质来鉴定JNK信号传导修饰剂。(3)通过体外结合试验和体内遗传分析，确定MSN激酶和PVR通路在形态发生期间选择性激活SLPR中的作用。目的是阐明MLK在发育系统中的需求，MLK对JNK信号的调节，以及MLK蛋白复合物对特定JNK信号输出的选择性招募。这些研究可能最终提出了一种治疗性操纵JNK信号传导的分子机制。

DESCRIPTION (provided by applicant): The fate of cells depends on their ability to sense and respond appropriately to their environment. The Jun Kinase (JNK) signal transduction pathway is activated in response to a wide variety of developmental and environmental signals to control fundamental cell behaviors, such as proliferation, differentiation, morphogenesis, and apoptosis, but the mechanisms that regulate the appropriate response to particular signals are poorly understood. Inappropriate activation of JNK signaling in humans can result in numerous disorders including chronic inflammation, cancer, and metabolic disease, while loss of JNK signaling early in development results in birth defects in mice. The overall objective of this proposal is to understand how JNK signaling is regulated to generate the appropriate responses in animal development and homeostasis. One way to regulate the appropriate response is to use unique combinations of signal transducers downstream from different signals. A candidate transducer that is selectively activated in certain JNK dependent processes in Drosophila is the Mixed Lineage Kinase (MLK), encoded by the slipper (slpr) locus. SLPR/MLK is an essential and specific regulator of tissue morphogenesis, which functions at the level of JNK Kinase Kinase (JNKKK) to stimulate JNK-dependent tissue reorganization. To investigate the molecular mechanisms by which SLPR/MLK regulates JNK signaling and tissue organization, we propose the following specific aims: (1) Characterization of essential functional domains of SLPR using phenotypic analysis of slpr mutant animals, coupled with expression of mutant, deleted, and chimeric JNKKK transgenes. (2) Identification of modifiers of JNK signaling by genetic screening for proteins that modify the defects associated with loss of SLPR function. (3) Determine the role of MSN Kinase and the PVR pathway in selective activation of SLPR during morphogenesis by in vitro binding assays and in vivo genetic analysis. The aims are designed to elucidate the requirement for MLK in a developmental system, the regulation of JNK signaling by MLK, and the selective recruitment of MLK protein complexes for specific JNK signaling outputs. These studies may ultimately suggest a molecular mechanism to manipulate JNK signaling therapeutically.