BIOLOGICAL FUNCTION OF THE HEMOCHROMATOSIS DISEASE GENE

这项提议的长期目标是理解生物作用 血色素沉着症基因，称为HFE，它携带一种 目前已知的最常见的突变。我们的目标是揭开 产品在铁质电路中的功能定位，并了解 它维持体内铁平衡的分子机制 肠细胞和网状内皮系统的细胞。HFE是独一无二的 高度分化的Ib类基因家族的成员，因此，它的 在小鼠中的表达似乎降级到巨噬细胞和 可能发挥其生物学效应的肠细胞(S)。不寻常 我们初步调查发现的特征包括HFE 细胞表面表达--即使在缺乏β-2m及其部分 依赖自来水运输。为了了解HFE的生物学作用， 我们将重点放在与HFE结构相关的三个具体目标上， 在体外和体内的表达及其与肠道的关系 铁通量和肿瘤坏死因子-α的反应性。具体来说，我们将确定 HFE细胞表面表达所需的元件(β2m和TAP)和 将决定结合的自体多肽的性质，如果是特定的，可以 预示了HFE折叠和运输的新机制。使用 在表达方面，我们将分析HFE的细胞内动力学 加工，特别注意它的局部相互作用 通过额外的蛋白质分子(受体或转运体)和它的 可能的亚蜂窝路由和本地化。源自我们的 初步数据显示HFe染色增加并伴随 肿瘤坏死因子-α染色阳性的上皮内淋巴细胞增多 铁负荷的小鼠，我们将继续关注小肠 在铁的挑战之后，将试图确定肿瘤坏死因子-α在 在控制和控制的范围内维持正常的铁动力学 击倒小鼠模型系统。我们的假设是，HFE作为 更大的复合体，在肠道中经历上调，以响应 铁导致巨噬细胞和肠道肿瘤坏死因子-α的增加 与肠细胞分化和铁的流动有直接关系。

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.