Effect of Heme on mRNA and miRNA Profile

血红素[铁原卟啉]是一种原始大环化合物，地球上几乎所有生命都依赖它。它有 多种已知功能和多种属性。血红素正常途径和调节的重要性 血红素稳态存在缺陷的疾病的严重性强调了新陈代谢。 例如，卟啉症是一组正常血红素合成存在缺陷的疾病，这是由于 主要是由于先天性代谢缺陷导致正常卟啉和酶的活性缺陷 血红素合成。在血红素代谢中特别重要的基因及其产物是 ALA 合酶 1 [ALAS1] 和血红素加氧酶 1 [HMOX1] 分别是血红素合成和血红素合成的速率控制酶 分解代谢。羟甲基双烷合酶 [HMBS] 是血红素生物合成途径的第三种酶， 缺乏急性间歇性卟啉症，这是最严重的急性卟啉症。近日，我们报道了 miRNA-122、-196 和 -let 7 对 HMOX1 及其关键阻遏蛋白表达的重要新作用 BACH1，我们最近发现了蛋白酶体和其他蛋白酶的新的和迄今为止意想不到的作用 调节 ALAS1、BACH1 和 HMOX1 水平的途径。我们还发现了由以下原因引起的变化 血红素过量与血红素缺乏对人肝细胞中 miRNA 和 mRNA 相互表达的影响。 血红素是急性卟啉症发作及其预防的首选治疗方法，可能具有 对肝脏和其他组织和器官有有害影响，特别是重复使用。我们最近的 人类 Huh-7 细胞的微阵列结果揭示了血红素过量与血红素缺乏对细胞的新影响 几个基因和途径。现在重要的是评估改变的潜在生理重要性 体外模型中的 miRNA 和 mRNA 谱以及体内是否发生以及在多大程度上发生类似的变化， 在 AIP 动物模型和患有急性卟啉症的人类中。我们假设血红素和其他 金属卟啉通过改变选定的 microRNA 来调节 ALAS1、HMBS 和 HMOX1 的表达 mRNA 谱 我们的具体目标如下： 目标 1：描绘效应和机制 由此选定的 microRNA 调节 ALAS1、HMBS 和 HMOX1 和/或其关键的表达 人肝细胞中的调节因子。目标 #2 表征选定的生理效应 具有突变的小鼠的肝脏、肾脏、脾脏和骨髓中的相关剂量的血红素 类似于人类 AIP 和 AIP 患者外周血单核细胞上的细胞 接受血红素治疗的人。这些研究的结果将为以下问题提供重要的新见解： 血红素在健康和疾病中以及在我们对基本和疾病的理解中具有多种和关键的功能 临床水平。

Heme [iron protoporphyrin] is a primordial macrocycle upon which nearly all life on earth depends. It has manifold known functions and diverse properties. The importance of a normal pathway and regulation of heme metabolism is underscored by the seriousness of diseases in which there are defects in heme homeostasis. For example, the porphyrias are a group of diseases in which there are defects in normal heme synthesis, due mainly to inborn errors of metabolism that produce deficient activities of the enzymes of normal porphyrin and heme synthesis. Genes and their products of particular importance in heme metabolism are ALA synthase 1 [ALAS1] and heme oxygenase 1 [HMOX1], respectively, the rate-controlling enzymes of heme synthesis and catabolism. Hydroxymethylbilane synthase [HMBS], the third enzyme of the heme biosynthetic pathway, is deficient in acute intermittent porphyria, the most severe of the acute porphyrias. Recently, we reported important novel effects of miRNAs-122, -196, and -let 7 on expression of HMOX1 and its key repressor BACH1, and we recently discovered new and heretofore unexpected roles of proteasomal and other protease pathways that regulate levels of ALAS1, BACH1, and HMOX1. We also have discovered changes caused by heme excess vs heme deficiency on reciprocal expression of miRNAs and mRNAs in human hepatocytes. Heme, which is the treatment of choice for acute porphyric attacks and for their prevention, may have deleterious effects on the liver and other tissues and organs, especially with repeated use. Our recent microarray results in human Huh-7 cells have unveiled novel effects of heme excess vs heme deficiency on several genes and pathways. It is important now to assess the potential physiological importance of alterations in miRNA and mRNA profiles in in vitro models and whether and to what extent similar changes occur in vivo, in animal models of AIP and in humans with acute porphyrias. We hypothesize that heme and other metalloporphyrins regulate ALAS1, HMBS and HMOX1 expression by altering selected microRNAs and mRNA profiles Our specific aims are as follows: Aim #1: To delineate effects and mechanisms whereby selected microRNAs modulate expression of ALAS1, HMBS, and HMOX1 and/or their key regulators in human hepatocytes. Aim #2 To characterize the effects of selected, physiologically relevant doses of heme on the livers, kidneys, spleens, and bone marrows of mice with mutations that resemble those seen in human AIP and on peripheral blood mononuclear cells of patients with AIP who are receiving heme as therapy. Results of these studies will provide important new insights into the manifold and critical functions of heme in health and disease, and in our understanding at both the basic and clinical level.