Investigating the role of the Neogenin-1/Netrin-1 axis in aging and lineage bias of hematopoietic stem cells (HSCs)

研究 Neogenin-1/Netrin-1 轴在造血干细胞 (HSC) 衰老和谱系偏向中的作用

• 批准号: 9759142
• 负责人: Gunsagar Singh Gulati
• 金额: $ 5万
• 依托单位: STANFORD UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-07-01 至 2021-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9759142
• 关键词: Adhesions; Adverse event; Age; Aging; B-Lymphocytes; Biological Assay; Blood; Bone Marrow; Brain; CD34 gene; Cell Aging; Cell Cycle; Cell Lineage; Cell Surface Receptors; Cells; Chemotactic Factors; Chimerism; Chronic; Clonal Expansion; Clonal Hematopoietic Stem Cell; Clone Cells; Colon; Comorbidity; Data; Endothelial Cells; Endothelium; Epigenetic Process; Exhibits; Fetal Liver; Flow Cytometry; Gene Expression; Genetic Transcription; Hematologic Neoplasms; Hematopoiesis; Hematopoietic; Hematopoietic Stem Cell heterogeneity; Hematopoietic Stem Cell subsets; Hematopoietic stem cells; Human; Image; Immune; Immune system; Impairment; In Vitro; Laboratories; Lead; Ligands; Location; Lymphoid; Lymphoid Cell; Measures; Membrane Proteins; Methods; Mus; Myelogenous; Myeloid Cells; NTN1 gene; Natural Killer Cells; Neurons; Organism; Output; Patients; Population; Process; Production; Proteins; Regulation; Research; Risk; Role; Somatic Mutation; Stem cells; T-Lymphocyte; Testing; Transcript; Transplant Recipients; Transplantation; adverse outcome; aged; bone aging; differential expression; granulocyte; hematopoietic stem cell expansion; laminin A; leukemia; migration; monocyte; morphogens; neogenin; novel; peripheral blood; prevent; prospective; reconstitution; stem cell population; young adult

PROJECT ABSTRACT Hematopoietic stem cells (HSCs) are defined by their ability to long-term reconstitute all blood and immune cells in a transplanted host. However, HSCs are heterogeneous and exhibit different degrees of reconstitution potential and biases towards certain cell lineages. This diversity in HSCs is a function of both intrinsic changes in the cells, such as acquired somatic mutations and epigenetic marks, and external influences such as local bone marrow morphogens and circulating factors in the blood. It is evident from the transplantation of low numbers of purified HSCs that there exist at least two types of HSCs distinguishable by their contribution to different hematopoietic lineages—myeloid-biased HSCs, which contribute more to granulocytes and monocytes than to T, B, and NK cells, and balanced HSCs, which contribute equally to all lineages. During aging, the myeloid-biased subset of HSCs clonally expands and predominates the old bone marrow, leading to impaired blood and immune production and an increased risk of leukemia and preleukemic adverse events. Still, the origin and identity of the myeloid-biased HSCs, much less a method to prospectively separate them from balanced HSCs, is unknown. Recently, we observed that Neogenin-1 (Neo-1), a cell surface receptor, marks a fraction of long-term reconstituting mouse Hoxb5+ HSCs and human CD34+CD38-CD90+CD45RA- HSCs. Serial transplantation of Neo-1+ and Neo-1- Hoxb5+ HSCs into sublethally irradiated hosts reveals that Neo-1 marks stable, myeloid-biased mouse Hoxb5+ HSCs, while Neo-1- Hoxb5+ HSCs are balanced or lymphoid-biased. Neo- 1+ Hoxb5+ HSCs also formed larger colonies in vitro and were more often in G2/S than Neo-1- Hoxb5+ HSCs. Furthermore, Netrin-1, a chemoattractant molecule and ligand to Neo-1, is expressed in bone marrow endothelial cells and its depletion in mice results in reduced number of myeloid cells in the peripheral blood compared to wildtype controls. Given this evidence, two specific aims are proposed: (1) To identify the functional and transcriptional differences between Neo-1+ and Neo-1- HSCs during mouse and human aging, and (2) To determine the bone marrow localization and characterize the myeloid-priming function of endothelial Netrin-1. Percent expansion and gene expression differences will be measured between Neo-1+ and Neo-1- HSCs in mice and humans with age. Aged Neo-1+ and Neo-1- Hoxb5+ HSCs will be transplanted into conditioned mice and their total and lineage chimerism will be compared to our data from young Neo-1+ and Neo-1- Hoxb5+ transplants. Furthermore, bone marrow from Hoxb5-mCherry mice will be imaged to localize Netrin-1-expressing cells, and the effect of Netrin-1 deletion in endothelial cells will be evaluated. These studies will provide novel information on HSC heterogeneity and stem cell reconstitution and advance our understanding of aging in hematopoiesis.

项目摘要