STRUCTURAL AND FUNCTIONAL STUDIES OF LEDGF

LEDGF的结构和功能研究

• 批准号: 2851740
• 负责人: TOSHIMICHI SHINOHARA
• 金额: $ 31.7万
• 依托单位: BRIGHAM AND WOMEN'S HOSPITAL
• 依托单位国家: 美国
• 财政年份: 1995
• 资助国家: 美国
• 起止时间: 1995-12-04 至 2003-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2851740
• 关键词: aging; animal tissue; autoradiography; cataract; cell membrane; cellular pathology; cytolysis; electron microscopy; enzyme linked immunosorbent assay; epithelium; growth factor; growth factor receptors; histopathology; laboratory mouse; lens; monoclonal antibody; organ culture; pathologic process; protein sequence; protein structure function; surface antigens

The lens is an unusual organ, containing three different cell types. One types does not divide but survives throughout life (central epithelial cells) another consists of dividing cells (epithelial cells in the mitotic zone), & the third is made up of enucleated fiber cells. Survival of central lens epithelial cells (LECs) may require continuous signaling by factors from LECs or other cells. Although most vertebrate cells require growth factors for their growth and proliferation during development, little is known about survival of mature central LECs A novel growth and survival factor was isolated from a human lens epithelial cell cDNA library with auto-antibodies (auto-Abs) cytocidal for LECs and named it lens epithelium-derived growth factor (LEDGF). As a growth factor LEDGF has both autocrine and paracrine effects on LECs, skin fibroblasts, and keratinocytes. It is secreted by the cell, binds to the cell surface, localizes in the nucleus, & regulates protein synthesis. LEDGF is a survival factor for the various cell types against heat- stress, serum starvation-stress, and oxidative-stress, in that the aforementioned cells do not survive without LEDGF. A basic mechanism of cellular survival against these stresses may be an elevated expression of the heat shock proteins (Hsps) 27 and alphaB-crystallin. Abs to LEDGF are prevalent in human sera, and neutralization of LEDGF by auto-Abs blocks cell growth and eventually leads to cell death. We speculate that death of epithelial cells and fibroblasts following the depletion of LEDGF by auto- Abs may be a risk factor for age-related cataract.. This research proposal comprises five aims. 1) To further establish LEDGF as a growth and survival factor for variety of cell types. 2) To determine functionally important sites in LEDGF. 3) To isolate the receptor of LEDGF and determine amino acid sequence. 4) To study expression and regulation of LEDGF and its receptor genes. 5) To investigate the mechanisms of survival of LECs in the presence LEDGF and of death of LECs in its absence. Studying the basic role of LEDGF in survival and death of LECs can enhance our standing of aging including development, growth, and age- related cataract.

晶状体是一种不寻常的器官，包含三种不同类型的细胞。一种类型不分裂但终生存活（中央上皮细胞），另一种由分裂细胞（有丝分裂区上皮细胞）组成，第三种由去核纤维细胞组成。中央晶状体上皮细胞（LECs）的存活可能需要LECs或其他细胞因子的持续信号传导。尽管大多数脊椎动物细胞在发育过程中需要生长和增殖因子，但对成熟中央型LECs的存活知之甚少。从具有LECs自身抗体（autoabs）的人晶状体上皮细胞cDNA文库中分离出一种新的生长和存活因子，并将其命名为晶状体上皮衍生生长因子（LEDGF）。作为一种生长因子，LEDGF对lec、皮肤成纤维细胞和角化细胞具有自分泌和旁分泌作用。它由细胞分泌，结合到细胞表面，定位于细胞核，调节蛋白质合成。LEDGF是各种细胞类型对抗热应激、血清饥饿应激和氧化应激的生存因子，因为上述细胞没有LEDGF就无法存活。细胞在这些应激条件下存活的基本机制可能是热休克蛋白（Hsps） 27和α -结晶蛋白的表达升高。针对LEDGF的抗体在人血清中普遍存在，自身抗体中和LEDGF会阻碍细胞生长并最终导致细胞死亡。我们推测上皮细胞和成纤维细胞在自身抗体耗尽LEDGF后死亡可能是年龄相关性白内障的危险因素。本研究计划包括五个目标。1)进一步确定LEDGF作为多种细胞类型的生长和存活因子。2)确定LEDGF中重要的功能位点。3)分离LEDGF受体，确定其氨基酸序列。4)研究LEDGF及其受体基因的表达与调控。5)探讨LEDGF存在时LECs存活和无LEDGF存在时LECs死亡的机制。研究LEDGF在LECs生存和死亡中的基本作用，可以提高我们对衰老的认识，包括发育、生长和年龄相关性白内障。