Regulation of JNK Signaling in Epidermal Morphogenesis

描述(申请人提供)：细胞的命运取决于它们感知环境并对环境做出适当反应的能力。Jun Kinase(JNK)信号转导通路被广泛的发育和环境信号激活，以控制基本的细胞行为，如增殖、分化、形态发生和凋亡，但调节特定信号的适当反应的机制尚不清楚。在人类中，JNK信号的不适当激活会导致许多疾病，包括慢性炎症、癌症和代谢性疾病，而在发育早期丢失JNK信号会导致小鼠出生缺陷。这项提案的总体目标是了解JNK信号是如何被调控的，以在动物发育和动态平衡中产生适当的反应。调节适当响应的一种方法是使用不同信号下游的独特信号换能器组合。在果蝇的某些JNK依赖过程中被选择性激活的候选转导分子是混合血统激酶(MLK)，由Slipper(Slpr)基因编码。SLPR/MLK是一种重要的、特异的组织形态发生调节因子，在JNKKK(JNK Kinase Kinase)水平上发挥作用，刺激JNK依赖的组织重组。为了研究SLPR/MLK调控JNK信号和组织结构的分子机制，我们提出了以下具体目标：(1)通过对SLPR突变动物的表型分析，结合突变、缺失和嵌合的JNKKK转基因表达，来描述SLPR的基本功能域。(2)通过遗传筛选修饰与SLPR功能丧失相关的缺陷的蛋白来识别JNK信号的修饰物。(3)通过体外结合试验和体内遗传学分析，确定MSN Kinase和PVR通路在SLPR形态发生选择性激活中的作用。这些目的是为了阐明在发育系统中对MLK的需求，MLK对JNK信号的调节，以及MLK蛋白复合体对特定JNK信号输出的选择性招募。这些研究最终可能提出一种分子机制来操纵JNK信号的治疗。

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.