Hemochromatosis modifier genes

血色病修饰基因

• 批准号: 7654668
• 负责人: RICHARD S AJIOKA
• 金额: $ 22.15万
• 依托单位: UNIVERSITY OF UTAH
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-07-01 至 2010-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7654668
• 关键词: Address; Affect; Alleles; Antibodies; Antibody Formation; Candidate Disease Gene; Cell Culture System; Chloride Ion; Chlorides; Chromosomes; Chromosomes, Human, 1-3; Chromosomes, Human, Pair 5; Clinical; Collection; Condition; Congenic Strain; Consomic Strain; Cultured Cells; Data; Databases; Dietary Iron; Distal; Enterocytes; Family; Funding; Gene Expression; Gene-Modified; Genes; Genetic; Genotype; Hemochromatosis; Hereditary hemochromatosis; Homeostasis; Homologous Gene; Homozygote; Human; In Vitro; Inbred Mouse; Iron; Laboratories; Liver; Localized; Maps; Measures; Mediating; Methods; Modeling; Mouse Strains; Mus; Mutation; Parents; Patients; Phenotype; Plasma; Proteins; Recombinants; Regulation; Risk Assessment; Sequence Homologs; Serum; Siblings; Signal Transduction; Spleen; Stratification; Syndrome; Testing; Therapeutic; Tissues; Transferrin; Zebrafish; absorption; abstracting; base; clinical phenotype; congenic; consomic; design; gene function; genetic pedigree; hepcidin; interest; iron metabolism; knock-down; member; protein expression; research study; response; transferrin receptor 2; uptake

Abstract: Homozygosity for a single mutation (HFE C282Y) is responsible for the vast majority of cases of hemochromatosis, yet phenotypic expression in homozygotes varies widely. The hypothesis to be tested in this amended competing renewal is that modifier genes are responsible for the phenotypic variability. To identify modifier genes, we propose three specific aims. Specific Aim 1: Identify candidate modifier genes on chromosomes affecting iron absorption. Iron metabolism in inbred mice varies in a strain-specific manner. The A/J strain is a "high iron" mouse and absorbs more iron and has higher liver iron content compared to the "low iron" C57BL/6J mouse. During the previous funding period, we phenotyped 21 chromosome substitution strains (CSS) that represent the 21 mouse chromosomes of A/J on an otherwise C57BL/6J genetic background. We used Recombinant Cogenic Strains (RCS) to localize a modifier region on the distal end of chromosome 5. Stratification of candidate genes will be based on tissue-specific expression differences between A/J, C57BL/6J and specific recombinant congenic strains. Specific Aim 2: Characterize the regulation of iron uptake, transport and export by the absorptive enterocyte. Preliminary results indicate that in the absence of an erythropoietic, iron stores, or hepcidin-mediated signal, the amount of iron mice absorb is regulated by a mechanism intrinsic to the enterocyte. We will identify genes that are differentially expressed in enterocytes during the response to altered dietary iron content. These regulated genes will become candidate modifier genes. Using this strategy we have identified at least two candidate modifier genes, transferrin receptor 2 and a member of the chloride transporter family. Specific Aim 3: Characterize candidate modifier genes that affect the iron phenotype in Hfe -/- mice and the homologous human genes in patients with hemochromatosis. Candidate modifier genes in the mouse will be sequenced, cloned, expressed in vitro and antibodies generated against the gene products. Western analysis will be used to confirm gene expression differences detected in Specific Aims 1 and 2. Candidate gene sequences will be determined in other high iron and low iron strains. A unique collection of human hemochromatosis pedigrees will be utilized to compare the sequences of homologous candidate modifier genes in sib pairs with concordant and discordant clinical phenotypes. Common alleles should be found among concordant sibs and not among discordant sibs. The function of candidate genes will be tested using cell culture models of iron transport and iron homeostasis. Identification of modifier genes may provide a method for risk assessment for hemochromatosis and possible therapeutic strategies.

摘要： 单一突变（HFE C282 Y）的纯合性是绝大多数HFE病例的原因。 在血色素沉着症中，纯合子的表型表达变化很大。待检验的假设 这种修正的竞争更新是修饰基因负责表型变异。到 确定修饰基因，我们提出了三个具体目标。 具体目标1：确定染色体上影响铁吸收的候选修饰基因。铁代谢 在近交系小鼠中以品系特异性方式变化。A/J品系是“高铁”小鼠，吸收更多的铁 并且与“低铁”C57 BL/6 J小鼠相比具有更高的肝脏铁含量。在过去的融资中 在此期间，我们对代表21条小鼠染色体的21个染色体置换株（CSS）进行了表型分析 A/J的C57 BL/6 J遗传背景。我们使用重组同源菌株（RCS）， 在5号染色体的远端定位修饰区。候选基因的分层将基于 A/J、C57 BL/6 J与特定重组同源菌株之间的组织特异性表达差异。 具体目标2：表征吸收性肠上皮细胞对铁摄取、转运和输出的调节。 初步结果表明，在缺乏红细胞生成、铁储存或铁调素介导的信号的情况下， 小鼠吸收的铁的量由肠上皮细胞固有的机制调节。我们将识别基因 在对改变的膳食铁含量的反应过程中在肠细胞中差异表达。这些 受调控的基因将成为候选修饰基因。使用这种策略，我们已经确定了至少两个 候选修饰基因，转铁蛋白受体2和氯转运蛋白家族的成员。 具体目标3：表征影响Hfe -/-小鼠中的铁表型的候选修饰基因，以及Hfe-/-小鼠中的铁表型。 血色素沉着症患者的同源人类基因。小鼠中的候选修饰基因将是 测序、克隆、体外表达和产生针对基因产物的抗体。Western分析 将用于确认特定目的1和2中检测到的基因表达差异。候选基因 将在其他高铁和低铁菌株中测定序列。独特的人类收藏 血色病家系将用于比较同源候选修饰物的序列 具有一致和不一致临床表型的同胞对中的基因。应该找到共同的等位基因 在和谐的同胞之间而不是在不和谐的同胞之间。候选基因的功能将使用 铁转运和铁稳态的细胞培养模型。修饰基因的鉴定可以提供 血色病的危险评估方法和可能的治疗策略。