Interaction of Transferrin-Endosomes with Mitochondria is Required for Iron Transport to Ferrochelatase in Erythroid Cells

红细胞中铁转运至铁螯合酶需要转铁蛋白内体与线粒体的相互作用

• 批准号: RGPIN-2018-06315
• 负责人: Ponka, Prem
• 金额: $ 2.4万
• 依托单位: McGill University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2018
• 资助国家: 加拿大
• 起止时间: 2018-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=662422
• 关键词: Interaction; Transferrin; Endosomes; Mitochondria; Required

Normal hemoglobinization of immature red blood cells requires iron (Fe) delivered by plasma transferrin (Tf), mediated by Tf receptors (TfR). Following the binding of diferric-Tf to its cognate receptor on the cell surface, the Tf-TfR complexes are internalized via endocytosis, and Fe is released from Tf by endosomal acidification and reduction by Steap3. Fe2+ is transported across the endosomal membrane by DMT1. The post-endosomal path of Fe within cells is controversial. The prevailing opinion is that a low molecular weight intermediate chaperones Fe transfer from endosomes to mitochondria. However, we have built a concept that, in hemoglobin-producing cells, there is a direct relaying of Fe from the endosomal machinery to that of the mitochondria; we have provided strong evidence for this “kiss and run” model (1). We propose that erythroid precursors have special adaptations that facilitate the high rate of iron transport from endosomes to mitochondria to meet the exceptionally high demand for heme synthesis.***The ultimate goal of this research project is to enhance our knowledge regarding iron and heme metabolism in erythroid cells. In three Specific Aims, we propose to:******1) Identify of the molecular partners involved in the endosme-mitochondria interaction in developing RBC;***2) Examine whether the cytoplasmic domain of TfR also interact with mitochondria;***3) Indentify the signal(s) that determine the attachment/detachment of Tf-endosome with/from mitochondria.******We will use a series of molecular and biochemical approaches in combination with cutting edge technology to analyze the interaction between endosomes and mitochondria and identify the molecular partners involved in these interactions.******We are confident that our proposal will provide strong support for the “kiss-and-run” hypothesis of the intracellular iron trafficking mechanism whereby Tf-containing endosomes cede their iron atoms directly to mitochondria. This investigation will not only enhance our understanding of this pathway, but will also strengthen our knowledge about intracellular trafficking of organelles that represents a “paradigm shift” in cell biology. Therefore, this study will have a strong impact on the academic research in Canada.******1. Hamdi et al. BBA 1863:2859, 2016

未成熟红细胞的正常血红蛋白化需要由血浆转铁蛋白（Tf）递送的铁（Fe），由Tf受体（TfR）介导。在diferric-Tf与其细胞表面上的同源受体结合后，Tf-TfR复合物通过内吞作用内化，并且Fe通过内体酸化和Steap 3还原从Tf释放。 Fe 2+通过DMT 1转运穿过内体膜。Fe在细胞内的后内体路径是有争议的。普遍的观点是，低分子量的中间伴侣铁从内体转移到线粒体。然而，我们已经建立了一个概念，即在血红蛋白产生细胞中，Fe从内体机制直接传递到线粒体机制;我们为这种“吻和跑”模型提供了强有力的证据（1）。我们认为红系前体细胞具有特殊的适应性，可以促进铁从内体到线粒体的高速率运输，以满足血红素合成的异常高需求。本研究项目的最终目标是提高我们对红系细胞中铁和血红素代谢的认识。在三个具体目标中，我们提出：**1）鉴定在发育RBC中参与内体-线粒体相互作用的分子伴侣;*2）检查Tf R的胞质结构域是否也与线粒体相互作用;*3）鉴定决定Tf-内体与线粒体附着/脱离的信号。**我们将使用一系列分子和生物化学方法结合尖端技术来分析内体和线粒体之间的相互作用，并确定参与这些相互作用的分子伴侣。我们有信心，我们的建议将提供强有力的支持，“吻和运行”的细胞内铁运输机制，含Tf的内体割让其铁原子直接线粒体的假说。这项研究不仅将增强我们对这一途径的理解，而且还将加强我们对细胞器细胞内运输的知识，这代表了细胞生物学的“范式转变”。因此，这项研究将对加拿大的学术研究产生强烈的影响。1. Hamdi等BBA 1863：2859，2016