BIOLOGICAL FUNCTION OF THE HEMOCHROMATOSIS DISEASE GENE

这项提案的长期目标是了解生物学作用 血色素沉着病基因，称为HFE，携带一个 目前已知的最常见的突变。目标是解开 产品在铁电路中的功能定位， 它通过分子机制维持铁平衡， 肠细胞和网状内皮系统的细胞。HFE是一个独特的 高度分化的Ib类基因家族的成员，因此，其 在小鼠中的表达似乎转移到巨噬细胞， 肠上皮细胞，在那里它可能发挥其生物学效应。不寻常 我们初步调查得出的特征包括HFE的 细胞表面表达，即使在β 2 m和其部分缺失的情况下， 依赖TAP运输。为了了解HFE的生物学作用， 我们关注与HFE结构相关的三个具体目标， 表达（体外和体内）及其与肠 铁通量和TNF-α反应性。具体来说，我们将确定 HFE细胞表面表达所需的元件（β 2 m和TAP）， 将决定结合的自身肽的性质，如果是特异性的， 预示着HFE折叠和运输的新机制。与 关于表达，我们将分析HFE的细胞内动力学， 处理，特别注意其部分相互作用 与其他蛋白质分子（受体或转运蛋白）以及其 可能的亚细胞路由和定位。从我们的 初步数据表明HFE染色增加， TNF-α阳性上皮内淋巴细胞染色增加， 铁负荷小鼠，我们将继续关注小肠 并将试图确定TNF-α在铁挑战后的作用， 在控制范围内维持正常的铁动力学， 敲除小鼠模型系统。我们的假设是，HFE，作为一个 更大的复合物，在肠道中进行上调，以响应 铁导致巨噬细胞和肠道TNF-α的增加， 与肠上皮细胞分化和铁通量直接相关。

The long-term goal of this proposal is to understand the biological role of the hemochromatosis disease gene, termed HFE, which carries one of the most common mutations currently known. The objectives are to unravel the product's functional niche in iron circuitry and to understand the molecular mechanisms through which it maintains iron balance in enterocytes and cells of the reticuloendothelial system. HFE is a unique member of the highly divergent class Ib gene family and as such, its expression in the mouse appears to be relegated to macrophages and enterocytes where it presumably exerts its biological effect(s). Unusual characteristics arising from our preliminary investigations include HFE's cell-surface expression even in the absence of beta2m and its partial dependence on TAP transport. In order to understand HFE's biological role, we have focused on three specific aims related to HFE's structure, expression (both in vitro and in vivo) and its relationship to intestinal iron flux and TNF-alpha responsiveness. Specifically, we will determine the elements required for HFE cell-surface expression (beta2m and TAP) and will determine the nature of bound self-peptide which, if specific, could herald a novel mechanism underlying HFE folding and transport. With respect to expression, we will analyze the kinetics of HFE's intracellular processing, paying particular attention to both its partial interaction with additional protein molecules (receptors or transporters) and to its possible subcellular routing and localization. Emanating from our preliminary data demonstrating increased HFE staining an a concomitant increase in intraepithelial lymphocytes staining positive for TNF-alpha in iron-loaded mice, we will continue to focus on the small intestine following iron challenge and will attempt to determine TNF-alpha's role in the maintenance of normal ferrokinetics within the context of control and knockout mouse model systems. Our hypothesis is that HFE, as part of a larger complex, undergoes up-regulation in the intestine in response to iron leading to an increase in macrophages and intestinal TNF-alpha which is directly related to enterocyte differentiation and iron flux.