Regulation of the lymphoid cell fate by Hoxa9

Hoxa9 对淋巴细胞命运的调节

• 批准号: 10390559
• 负责人: Kay Lynn Medina
• 金额: $ 31.8万
• 依托单位: MAYO CLINIC ROCHESTER
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-01-15 至 2024-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10390559
• 关键词: Age; Aging; Attention; B-Lymphocytes; Blood Cells; Bone Marrow; CDKN2A gene; Cell Compartmentation; Cell Lineage; Cells; Cellularity; Common Lymphoid Progenitor; Cyclin-Dependent Kinase Inhibitor; Data; Defect; Development; Elderly; Exhibits; Frequencies; Genes; Goals; HOXA9 protein; Hematology; Hematopoiesis; Hematopoietic; Hematopoietic Stem Cell subsets; Hematopoietic stem cells; Homeobox; Immune System Diseases; Immunocompetence; Impairment; In Vitro; Infection; Knockout Mice; Knowledge; Life; Lymphocyte; Lymphoid; Lymphoid Cell; Lymphopoiesis; Maintenance; Marrow; Messenger RNA; Modeling; Molecular; Mus; Myelogenous; Output; Publications; Radiation Chimera; Regulation; Role; SLAM protein; T-Lymphocyte; Thymus Gland; Transcript; Transplantation; Tumor Suppressor Genes; aged; cytokine; experimental study; genomic locus; humoral immunity deficiency; immune function; novel; novel therapeutics; overexpression; p19ARF; progenitor; promoter; response; senescence; stem cell biology; stem cells; transcription factor; tumorigenesis; vaccine response; virtual; young adult

PROJECT SUMMARY Steady-state hematopoiesis in bone marrow is critical for maintenance of blood cell genesis and immune competence throughout life. Concomitant with aging, the bone marrow hematopoietic stem cell (HSC) compartment undergoes cell intrinsic and extrinsic changes that biases hematopoietic output toward the myeloid lineage. The bias in HSC-subset predominance and change in hematopoietic output contributes to immune dysfunction in the elderly including an increased propensity to infection and lessened vaccine responses. Thus, studies focused on understanding essential regulators that support a non-biased, balanced HSC pool that supports lymphoid differentiation capability has the potential to provide novel therapeutic avenues to rejuvenate HSC developmental trajectories to restore immune function in the aged. The homeobox transcription factor Hoxa9 is expressed in primitive HSCs and is inactivated upon lineage commitment. Mice with germline deletion of hoxa9 are viable but display multilineage deficiencies that are transplantable, confirming a cell intrinsic defect. Competitive transplantation experiments revealed impaired long-term repopulating ability and in vitro studies showed poor proliferative responses to early-acting cytokines. In bone marrow, hoxa9-/- mice exhibit reduced cellularity, impaired lymphoid priming, reductions in lympho-myeloid progenitors, common lymphoid progenitors, and B cell precursors. Hoxa9-/- mice also have smaller thymi, and reductions in early thymic progenitors. Interestingly, flow cytometric analysis of the long-term repopulating stem cell compartment (LT-HSC) in young adult hoxa9-/- mice revealed increased frequencies of LT-HSCs expressing high levels of the CD150, which is functionally associated with myeloid skewing. This is contrasted by significant decreases in frequencies of CD150lo LT-HSC in hoxa9-/- marrow, which have balanced lympho- myeloid potential. Increased numbers of myeloid-biased HSCs along with diminished lymphopoiesis is reminiscent of aging. A Hoxa9 target gene implicated in age-associated alterations in lymphopoiesis and B cell genesis in the marrow is p16ink4a. The cyclin dependent kinase inhibitor p16ink4a is virtually undetectable in HSC and B cell precursors from young mice but increases in both subsets with age. Realtime PCR of Lin- Sca1+ hematopoietic progenitors from young hoxa9-/- mice revealed increased mRNA transcripts for p16ink4a. To determine if over expression of p16ink4a was the molecular basis of the lymphoid/B cell deficiency in hoxa9-/- mice, we generated hoxa9-/-p16ink4a-/- mice. Importantly, deletion of p16ink4a restored bone marrow and thymus cellularity and rescued the deficiencies in lymphoid, B and T cell precursors in hoxa9-/- mice. These novel experimental findings support the hypothesis that Hoxa9 suppression of p16ink4a is critical for lymphopoiesis. At present, there is a paucity of information regarding the role of Hoxa9 in regulation of lympho-hematopoiesis. The studies detailed in this proposal are aimed at filling this gap in the knowledge.

项目摘要 骨髓中的稳态造血对维持血细胞的起源至关重要 一生的能力。与衰老，骨髓造血干细胞（HSC）伴随 隔室经历细胞的固有和外在变化，使造血输出偏向于 髓样谱系。 HSC-subset优势和造血产量的变化的偏见有助于 老年人的免疫功能障碍，包括增加感染倾向和疫苗的倾向 回答。因此，研究重点是理解支持无偏见，平衡的基本调节剂 支持淋巴分化能力的HSC池具有提供新型治疗的潜力 恢复HSC发育轨迹以恢复老年免疫功能的途径。同型 转录因子HOXA9在原始HSC中表达，并在谱系承诺时灭活。老鼠 hoxa9的种系缺失是可行的，但显示出可移植的多限性缺陷， 确认细胞内在缺陷。竞争性移植实验显示长期受损 重新培养能力和体外研究表明，对早期作用细胞因子的增殖反应不佳。在骨头 骨髓，Hoxa9 - / - 小鼠表现出降低的细胞性，受损的淋巴启动，淋巴蛋白酶的降低 祖细胞，常见的淋巴样祖细胞和B细胞前体。 Hoxa9 - / - 小鼠的百里香也较小，并且 早期胸腺祖细胞的减少。有趣的是，长期重塑茎的流式细胞仪分析 年轻成人Hoxa9 - / - 小鼠的细胞室（LT-HSC）显示LT-HSC的频率增加 表达高水平的CD150，在功能上与髓样偏斜相关。这是对比的 通过在Hoxa9 - / - 骨髓中CD150lo LT-HSC的频率显着降低，它们具有平衡的淋巴 - 髓样潜力。增加的髓样偏见的HSC数量以及淋巴细胞的减少为 让人联想到衰老。 HOXA9靶基因与年龄相关的淋巴管和B细胞的改变有关 骨髓中的创世纪是p16ink4a。在 来自小鼠的HSC和B细胞前体，但随着年龄的增长而增加。 Lin-实时PCR 来自年轻Hoxa9 - / - 小鼠的SCA1+造血祖细胞显示，MRNA转录本增加了 p16ink4a。确定p16Ink4a的过度表达是否是淋巴/B细胞的分子基础 Hoxa9 - / - 小鼠的不足，我们生成了Hoxa9 - / - P16Ink4a - / - 小鼠。重要的是，删除p16ink4a已恢复 骨髓和胸腺细胞性，并挽救了淋巴机，B和T细胞前体的缺陷 Hoxa9 - / - 小鼠。这些新的实验发现支持了Hoxa9抑制p16Ink4a的假设 对于淋巴管至关重要。目前，关于Hoxa9在 调节淋巴 - 毛to菌。该提案中详细介绍的研究旨在填补这一空白 知识。