Regulation and function of mammalian HSF4 in vivo

描述（由申请人提供）：哺乳动物热休克转录因子（Hsfs）的功能随着最近一代缺乏hsf 1或hsf 2的小鼠而变得越来越清楚。从这些动物模型的分析中产生的结果是惊人的，并指示Hsfs在细胞凋亡，分化和发育以及维持组织稳态中的作用。为了了解Hsfs在体内的功能，我们已经产生了hsf 1和hsf 2敲除小鼠，现在正在努力创造不表达hsf 4的小鼠。hsfl的破坏阐明了其在调节细胞凋亡、控制耐热性和雌性不育中的重要性。相反，hsf 2基因敲除小鼠表现出中枢神经系统发育缺陷和精子发生减少。我们进一步证明了hsf 1和hsf 2的缺失会导致协同效应和缺陷，比单独的hsf-deficient小鼠表现出的更严重。这些缺陷与大脑和行为异常，精子发生和男性不育的完全中断以及其他有关。与Hsf 1和Hsf 2相比，对哺乳动物Hsf家族的唯一剩余成员Hsf 4的了解相对较少。有几个特征将Hsf 4与其他Hsfs区分开来。它表达为两种可变剪接变体，一种形式是转录激活因子，另一种是转录抑制因子，这两种变体在不同组织中差异表达。我们发现，Hsf 4是磷酸化和一种新的磷酸酶（命名为DSPH 4）含有签名图案的双特异性酪氨酸/丝氨酸/苏氨酸磷酸酶已被确定，结合到Hsf 4和调节其磷酸化状态，DNA结合能力和核定位。这代表了通过细胞外信号调节Hsf 4活性的可能机制。由于Hsfl和Hsf 2具有不同的功能、调节机制和靶基因，但显示出一些功能上的相互依赖性，因此合理地假设Hsf 4也将与Hsfl和Hsf 2具有一些重叠的功能，而且在维持细胞内稳态中具有其自身独特的作用。本授权申请中概述的研究旨在了解Hsf 4在分子水平上的调节，并检查Hsf 4不仅单独的功能，而且与体内Hsf 1和Hsf 2功能协调的功能。该提案的具体目标是：1。了解哺乳动物细胞中Hsf 4调控的分子机制。2.探讨Hsf 4在动物模型中的作用。3.了解Hsf 4剪接变异体在动物模型中的功能。

DESCRIPTION (provided by applicant): The functions of the mammalian heat shock transcription factors (Hsfs) are becoming increasingly clear with the recent generation of mice lacking the hsfl or hsf2. The results generated from analyses of these animal models are striking and indicative of the role of Hsfs in apoptosis, differentiation and development as well as maintenance of tissue homeostasis. To understand the functions of Hsfs in vivo, we have generated hsfl and hsf2 knockout mice and are now working to create mice that do not express hsf4. Disruption of hsfl illuminates its importance for regulation of apoptosis and control of thermotolerance and female sterility. In contrast, the hsf2 knockout mouse exhibits defects in development of the central nervous system and reduction in spermatogenesis. We further show evidence that deletion of both hsfl and hsf2 leads to synergistic effects and defects that are more severe than those manifested in individual hsf-deficient mice. These defects are associated with brain and behavioral abnormalities, and complete disruption of spermatogenesis and male sterility, as well as others. Compared to Hsfl and Hsf2, relatively little is known about the only remaining member of the mammalian Hsf family, Hsf4. Several features distinguish Hsf4 from other Hsfs. It is expressed as two alternatively spliced variants with one form being a transcriptional activator and the other a transcriptional repressor and these two variants are differentially expressed in different tissues. We show that Hsf4 is phosphorylated and a novel phosphatase (named DSPH4) containing signature motifs of the dual specificity tyrosine/serine/threonine phosphatases has been identified that binds to Hsf4 and modulates its phosphorylation status, DNA binding ability and nuclear localization. This represents a possible mechanism for the regulation of Hsf4 activity by extracellular signals. Because Hsfl and Hsf2 possess distinct functions, regulatory mechanisms, and target genes, but show some functional interdependency, it is reasonable to postulate that Hsf4 will also have some overlapping function with Hsfl and Hsf2, but also its own unique roles in maintaining cellular homeostasis. The studies outlined in this grant application are directed to understand the regulation of Hsf4 at the molecular level and to examine the function of Hsf4 not only alone, but also in coordination with Hsfl and Hsf2 functions in vivo. The Specific Aims of this proposal are: 1. To understand the molecular mechanisms of Hsf4 regulation in mammalian cells. 2. To investigate the function of Hsf4 in animal models. 3. To understand the function of Hsf4 splice variants in animal models.