Osmotic responsiveness of the master immune regulator PU.1

主免疫调节剂 PU.1 的渗透反应性

• 批准号: 8770311
• 负责人: Gregory Man Kai Poon
• 金额: $ 32.94万
• 依托单位: WASHINGTON STATE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-08-01 至 2014-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8770311
• 关键词: Activated Lymphocyte; Affect; Affinity; Attention; Binding; Biological; Biological Response Modifiers; Cell Death; Cell Proliferation; Cells; Complement; Coupled; Coupling; DNA; DNA Binding; DNA Sequence; Development; Diabetes Mellitus; Discrimination; Disease; Electrostatics; Elements; Environment; Exposure to; Face; Family; Family member; Gene Expression Regulation; Gene Targeting; Genes; Genomics; Goals; Homologous Gene; Human; Hydration status; Hydrogen Bonding; Immune; Immune System Diseases; Immune response; Immune system; Immunology; Inflammation; Inflammatory; Ions; Knowledge; Lead; Lymphocyte; Lymphoid Tissue; Mediating; Molecular; Mutate; Nature; Osmolalities; Physical environment; Physiological; Play; Positioning Attribute; Proteins; Regulation; Research; Role; Site; Solutions; Specificity; Stress; Structure; T-Lymphocyte; Testing; Thermodynamics; Thymus Gland; Variant; Water; base; biological adaptation to stress; immune function; improved; in vivo; interfacial; knock-down; macrophage; member; novel; pathogen; prevent; programs; public health relevance; solute; transcription factor

DESCRIPTION (provided by applicant): Immune cells such as macrophages and activated lymphocytes are highly sensitive to osmotic stress from exposure to hyperosmotic environments (such as lymphoid tissues and local inflammation) or active cell proliferation. Cells adapt to osmotic stress by accumulating compatible osmolytes, which allow cells to efficiently retain intracellular water, maintain cytoplasmic volume, and dilute cellular ions and other critical solutes. Accumulating osmolytes significantly raise the intracellular solution osmolality, or equivalently reduce water activity. Macromolecular interactions coupled to large changes in hydration are therefore sensitive to osmotic changes inside the cell. PU.1 is an ETS-family transcription factor that regulates the development and function of immune cells such as macrophages and lymphocytes. Our recent studies have demonstrated that DNA-binding affinity and sequence selectivity for PU.1 are profoundly sensitive to their osmotic environment, but not for its close structural homolog, Ets-1. Independently, genomic studies show that regulation of PU.1-target genes, but not Ets-1 target genes, depend strongly on a functional osmotic stress response. Based on this evidence, we hypothesize that osmotic sensitivity is a mechanism for biological responsiveness and target specificity for PU.1. To test our hypothesis, we will determine the physicochemical nature of osmotic sensitivity by PU.1 and identify the structural elements that confer its osmotic sensitivity. We will use Ets-1 as an osmotically insensitive "standard" to interpret how osmotic sensitivity is specifically incorporated into PU.1, and how osmotic sensitivity affects site selectivity (the primary determinant of gene-activating potential) These proposed studies complement more than two decades of cellular and functional studies of PU.1 and other ETS transcription factors in culture and in vivo. They have specific relevance to how PU.1 and Ets-1 coordinately modulate their activities to permit correct maturation of T lymphocytes in the hyperosmotic thymus environment. Upon completion of this research, we expect to have established osmotic sensitivity as a mechanism for responsiveness by PU.1 to the cellular osmotic stress response program. More broadly, this research brings attention to hydration as a biophysical basis for responsiveness to physiologic osmotic stress in human cells. This knowledge has potential implication for our understanding of "anisotonic disorders" (such as diabetes mellitus and inflammation) associated with pathological intracellular osmotic stress.

描述（由申请方提供）：免疫细胞如巨噬细胞和活化淋巴细胞对暴露于高渗环境（如淋巴组织和局部炎症）或活性细胞增殖的渗透压高度敏感。细胞通过积累相容的渗透剂来适应渗透胁迫，渗透剂允许细胞有效地保留细胞内水，维持细胞质体积，并稀释细胞离子和其他关键溶质。渗透压物质的积累显著提高了细胞内溶液的渗透压，或等效地降低了水活度。大分子间的相互作用与水合作用的巨大变化相结合，因此对细胞内的渗透压变化很敏感。PU.1是调节免疫细胞如巨噬细胞和淋巴细胞的发育和功能的ETS家族转录因子。我们最近的研究表明，PU.1的DNA结合亲和力和序列选择性对其渗透环境非常敏感，但对其结构同源物Ets-1则不敏感。独立地，基因组研究表明，PU.1靶基因的调节，但不是Ets-1靶基因，强烈依赖于功能性渗透胁迫反应。基于这一证据，我们假设渗透敏感性是PU的生物反应性和靶特异性的机制。为了验证我们的假设，我们将确定渗透敏感性的物理化学性质的PU.1和识别的结构元素，赋予其渗透敏感性。我们将使用Ets-1作为一个对渗透敏感性不敏感的“标准”来解释渗透敏感性是如何被特异性地整合到PU.1中的，以及渗透敏感性如何影响位点选择性（基因激活潜力的主要决定因素）。这些拟议的研究补充了二十多年来对PU.1和其他ETS转录因子在培养和体内的细胞和功能研究。它们与PU.1和Ets-1如何协调调节其活性以允许T淋巴细胞在高渗胸腺环境中正确成熟具有特定相关性。在完成这项研究后，我们希望已经建立了渗透敏感性作为一种机制的响应PU.1的细胞渗透应激反应程序。更广泛地说，这项研究引起了人们对水合作用的关注，水合作用是人体细胞对生理渗透压反应的生物物理基础。这一知识对我们理解与病理性细胞内渗透应力相关的“非等渗性疾病”（如糖尿病和炎症）具有潜在意义。