Genetic and Molecular Approaches to Signaling by Intracellular Receptors

在转录调控因子整合信号信息的几个层面上，对分子机制的持续研究有五个具体目标。1. 扩展对一种特殊分子伴侣复合物（包括Hsp90和其他成分）的分析，以接近其“调节”已知最大一类调节剂的机制，即细胞内受体（IRs）对其激素配体敏感，并测试伴侣复合物本身是向载脂蛋白受体传递信息的信号成分的可能性；2. 寻求以下发现：应答元件，即IRs结合的基因组位点，赋予影响转录调控模式的信号信息，例如，由该元件施加的激活或抑制；分析反应元件固有的信号和受体内部的感知和解释机制；3. 对糖皮质激素受体（GR）和甲状腺受体（TR）的激素结合域进行广泛分析，寻求其机制的共同和独特之处；4. 分离并鉴定一种ABC转运体的哺乳动物同源物，该转运体首先从酵母中分离出来，可选择性地输出某些类固醇；寻找影响类固醇细胞内功效和效力的其他成分，并确定这些膜成分是否有助于激素活性的细胞特异性；5. 研究GR磷酸化的功能后果，并测试最近检测到的GR和TR与周期蛋白依赖性激酶抑制剂（称为INKs）相互作用导致受体和/或CDK活性改变的可能性，从而构成信号集成电路。多细胞真核生物的基因受到复杂的调控，通常在不同的细胞类型、发育阶段或生理条件下受到不同的调控。理解这种复杂性的机制是现代生物学的首要问题。很明显，许多转录调控因子，即直接或间接与RNA聚合机制相互作用的因子，位于信号转导通路的末端，信号转导通路感知各种生物信号并沿着网络传递信息。

9604938 Yamamoto Technical Section There are five specific aims for this continuing investigation into the molecular mechanisms at several levels whereby signaling information is integrated by transcription regulators. 1. Extend the analysis of a specialized molecular chaperone complex, which includes Hsp90 and other components, to approach the mechanism by which it 'poises' the largest known class of regulators, the intracellular receptors (IRs)to be sensitive to their hormonal ligands, and to test the possibility that the chaperone complex is itself a signaling component that conveys information to aporeceptors; 2. Pursue findings that response elements, genomic sites to which IRs bind, confer signaling information that influences the mode of transcriptional regulation, e.g., activation or repression, that is imposed from the element; analyze both the signals intrinsic to the response elements and the sensing and interpretation mechanism within the receptors; 3. Carry out extensive analysis of the hormone binding domains of the glucocorticoid receptor (GR) and the thyroid receptor (TR), seeking common and unique features of their mechanisms; 4. Isolate and characterize a mammalian homolog of an ABC transporter first isolated in yeast that selectively exports certain steroids; seek other components that affect intracellular efficacy and potency of steroids, and ascertain whether such membrane components contribute to the cell specificity of hormone activity; 5. Investigate the functional consequences of GR phosphorylation, and test the possibility that recently detected interactions of GR and TR with cyclin-dependent kinase inhibitors termed INKs result in alterations of receptor and/or CDK activities and thereby comprise a signal integration circuit. Non-technical Section Genes in multicellular eukaryotes are subject to complex regulation, typically being regulated differentially in different cell types, developmental stages or physiological conditions. Understanding the mecha nisms of this complexity is an overarching problem in modern biology. It is apparent that many transcription regulators, factors that interact directly or indirectly with the RNA polymerization machinery, are at the distal end of signal transduction pathways that sense various biological signals and pass that information along a network.