Mechanisms of Intercellular Heme Homeostasis in Liver

肝脏细胞间血红素稳态机制

• 批准号: 10567065
• 负责人: Makiko Yasuda
• 金额: $ 65.54万
• 依托单位: ICAHN SCHOOL OF MEDICINE AT MOUNT SINAI
• 依托单位国家: 美国
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-04-01 至 2027-03-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10567065
• 关键词: Ablation; Acute; Adult; Aminolevulinic Acid; Biological Process; Candidate Disease Gene; Cells; Coculture Techniques; Disease; Endothelial Cells; Enzymes; Equilibrium; Erythrocytes; Feline Leukemia Virus; Funding; Genes; Genetic; Goals; Grant; Health; Heme; Heme Iron; Hemeproteins; Hemopexin; Hepatic; Hepatic Porphyrias; Hepatocyte; Homeostasis; Hydrophobicity; In Vitro; Inherited; Iron; Knockout Mice; Knowledge; Life; Liver; Liver diseases; Macrophage; Maintenance; Mammalian Cell; Mammals; Mediating; Membrane; Molecular; Mus; Pathogenesis; Pathway interactions; Process; Recycling; Signal Transduction; Signaling Molecule; Subgroup; System; Testing; candidate identification; cell type; clinically relevant; cofactor; cytotoxic; heme a; heme biosynthesis; improved; in vivo; mouse model; novel; receptor; senescence; single-cell RNA sequencing; trafficking

(PLEASE KEEP IN WORD, DO NOT PDF) The long-term goal of this grant is to obtain a comprehensive understanding of the intercellular mechanisms involved in the maintenance of organismal heme homeostasis. In mammals, heme, an iron-containing cofactor and signaling molecule, is synthesized in all nucleated cells and is essential for a diverse array of fundamental biological processes. As a hydrophobic and cytotoxic molecule, heme must be transported in a highly controlled manner through membranes via specific cellular pathways. The current paradigm posits that mammalian cellular heme homeostasis is maintained solely by the balance between heme biosynthesis, driven by 5-aminolevulinic acid synthase (ALAS), and heme degradation. While the discovery of eukaryotic heme transporters has given rise to the emerging notion that inter- and intra-cellular heme trafficking pathways also contribute to the maintenance of heme homeostasis, the pathways and mechanisms that mediate heme homeostasis outside of the context of heme biosynthesis and heme degradation remain poorly understood. Our recent unpublished studies using a newly generated hepatocyte-specific ALAS knockout mouse model (Alas1/2KO mice) strongly suggest that hepatocytes acquire “on demand” heme from reticuloendothelial macrophages through a currently unexplored intercellular heme homeostatic pathway. In this proposal, we will test our paradigm-shifting hypothesis that hepatocytes maintain cellular heme homeostasis by acquiring a substantial portion of their heme from macrophages using the Alas1/2KO mice. To this end, Specific Aim 1 will identify the cell types that are directly involved in heme transfer from macrophages to hepatocytes by establishing an in vitro primary liver cell co-culture system. Specific Aim 2 will employ in vivo approaches to identify key molecules involved in the hepatocyte heme acquisition pathway and to investigate the mechanisms by which the acquisition system is activated. Specific Aim 3 will identify additional candidate genes and pathways that drive hepatocyte heme acquisition using single cell RNA sequencing. These studies will advance our understanding of how liver maintains heme homeostasis in health and disease and may aid in improving our understanding of the pathogenesis of the life-threatening acute neurovisceral attacks that occur in the acute hepatic porphyrias.

（请以 WORD 形式保存，请勿以 PDF 形式保存） 该资助的长期目标是全面了解维持有机体血红素稳态的细胞间机制，血红素是一种含铁辅助因子和信号分子，在所有有核细胞中合成，并且是必不可少的。作为一种疏水性和细胞毒性分子，血红素必须通过特定的细胞途径以高度受控的方式穿过细胞膜。体内平衡仅通过 5-氨基乙酰丙酸合酶 (ALAS) 驱动的血红素生物合成和血红素降解之间的平衡来维持，而真核血红素转运蛋白的发现引起了细胞间和细胞内血红素运输途径的新概念。也有助于维持血红素稳态，但在血红素生物合成和血红素降解背景之外介导血红素稳态的途径和机制仍然知之甚少。我们最近使用新生成的肝细胞特异性 ALAS 敲除小鼠模型（Alas1/2KO 小鼠）进行的未发表的研究强烈表明，肝细胞通过目前尚未探索的细胞间血红素稳态途径从网状内皮巨噬细胞获取“按需”血红素。我们的范式转变假设是，肝细胞通过使用 Alas1/2KO 小鼠从巨噬细胞获取大部分血红素来维持细胞血红素稳态。为此，Specific Aim 1 将通过建立体外原代肝细胞共培养系统来鉴定直接参与血红素从巨噬细胞转移到肝细胞的细胞类型，Specific Aim 2 将采用体内方法来鉴定参与血红素转移的关键分子。具体目标 3 将利用单细胞 RNA 测序确定驱动肝细胞血红素获取的其他候选基因和途径，这些研究将增进我们对肝脏如何维持的理解。健康和疾病中的血红素稳态，可能有助于提高我们对急性肝卟啉症中发生的危及生命的急性神经内脏发作的发病机制的了解。