Regulation and function of mammalian HSF4 in vivo

哺乳动物HSF4体内的调控和功能

基本信息

批准号：
7003659
负责人：
NAHID F MIVECHI
金额：
$ 25.83万
依托单位：
AUGUSTA UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2000
资助国家：
美国
起止时间：
2000-03-01 至 2007-11-30
项目状态：
已结题

项目摘要

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.

描述（由申请人提供）：随着最近一代缺乏hsf1或hsf2的小鼠，哺乳动物热休克转录因子（Hsfs）的功能变得越来越清楚。对这些动物模型的分析产生的结果是惊人的，表明 Hsfs 在细胞凋亡、分化和发育以及组织稳态维持中的作用。为了了解 Hsfs 在体内的功能，我们已经生成了 hsfl 和 hsf2 敲除小鼠，现在正在努力创建不表达 hsf4 的小鼠。 hsfl 的破坏阐明了它对于调节细胞凋亡以及控制耐热性和雌性不育的重要性。相比之下，hsf2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，hsf1 和 hsf2 的缺失会导致协同效应和缺陷，这些效应和缺陷比个体 hsf 缺陷小鼠中表现的更严重。这些缺陷与大脑和行为异常、精子发生完全破坏和男性不育等有关。与 Hsf1 和 Hsf2 相比，人们对哺乳动物 Hsf 家族仅存的成员 Hsf4 知之甚少。 Hsf4 与其他 Hsf 的区别有几个特征。它表达为两种可变剪接变体，一种形式是转录激活子，另一种形式是转录抑制子，这两种变体在不同组织中差异表达。我们发现 Hsf4 被磷酸化，并且已鉴定出一种包含双特异性酪氨酸/丝氨酸/苏氨酸磷酸酶特征基序的新型磷酸酶（称为 DSPH4），它与 Hsf4 结合并调节其磷酸化状态、DNA 结合能力和核定位。这代表了细胞外信号调节 Hsf4 活性的可能机制。由于Hsf1和Hsf2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，因此可以合理地假设Hsf4也将与Hsf1和Hsf2具有一些重叠的功能，但在维持细胞稳态方面也有其独特的作用。本拨款申请中概述的研究旨在了解 Hsf4 在分子水平上的调节，并不仅检查 Hsf4 的功能，而且还检查 Hsf4 与体内 Hsf1 和 Hsf2 功能的协调。该提案的具体目标是： 1.了解哺乳动物细胞中Hsf4调控的分子机制。 2. 探讨Hsf4在动物模型中的功能。 3.了解Hsf4剪接变异体在动物模型中的功能。