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Role of the Class IA PI3K in Hematopoietic Stem Cell Self-Renewal

IA 类 PI3K 在造血干细胞自我更新中的作用

基本信息

批准号：
10311531
负责人：
Kristina Ames
金额：
$ 7.64万
依托单位：
ALBERT EINSTEIN COLLEGE OF MEDICINE
依托单位国家：
美国
项目类别：
财政年份：
2020
资助国家：
美国
起止时间：
2020-01-01 至 2022-12-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/10311531
关键词：
3-Phosphoinositide Dependent Protein Kinase-1 AKT Signaling Pathway Adult Autophagocytosis Binding Biological Assay Biological Models Blood Bone Marrow Cancer Patient Cell Aging Cell Count Cell division Cells Cellular Metabolic Process Clinic Clinical Cytokine Signaling DNA Damage Data Drug Targeting Embryo Equilibrium Fibroblasts Flow Cytometry Frequencies Functional disorder G-Protein-Coupled Receptors GTF2H1 gene Genus Hippocampus Growth Factor Guanosine Triphosphate Phosphohydrolases Hematology Hematopoiesis Hematopoietic Hematopoietic stem cells Impairment Individual Knock-out Knockout Mice Maintenance Malignant Neoplasms Metabolic Modeling Molecular Mus Numbness Pathologic Pathway interactions Patients Phenocopy Phenotype Phosphatidylinositols Phosphotransferases Play Process Property Protein Isoforms Proteins Reactive Oxygen Species Receptor Protein-Tyrosine Kinases Recycling Research Role Safety Signal Transduction Sirolimus Structure System Toxic effect Transplantation Work cancer therapy chemokine deprivation fitness hematopoietic stem cell differentiation hematopoietic stem cell expansion hematopoietic stem cell self-renewal in vivo inhibitor kinase inhibitor knockout animal leukemia mTOR Inhibitor mouse model mutant progenitor self-renewal stem cell function stem cell population stem cell self renewal therapeutic target

项目摘要

Proposal Summary/Abstract Adult hematopoietic stem cells (HSCs) are a rare and unique population of stem cells that reside in the bone marrow, where they undergo self-renewal and differentiation to maintain the blood system. To properly maintain the balance between self-renewal and differentiation, HSCs receive signals from growth factors and chemokines to activate the evolutionarily conserved phosphoinositide 3-kinase/Protein Kinase B (PI3K/AKT) signaling pathway. Pathologic activation of this pathway is frequently observed in cancers, including leukemia, making it a desirable target for cancer treatment. Several PI3K inhibitors are already used in the clinic and to better inform therapeutic targeting, it is crucial to understand the roles of PI3K in adult HSCs. Hematopoietic cells express three Class IA catalytic isoforms of PI3K (p110α, β, δ), all of which can transduce growth factor and cytokines signals. Out of these isoforms, p110β is unique, since in addition to transducing growth factor signals through receptor tyrosine kinases (RTK), it can directly interact with G-protein coupled receptor Gβɣ subunits to transduce chemokines, and also binds to RAC and to RAB5 GTPases. In mouse embryonic fibroblasts, the p110β-RAB5 interaction was shown to be important for the induction of autophagic cellular recycling process, which is essential for the maintenance of HSC metabolism and self- renewal. Individual Class 1A PI3K isoforms have unique functions in mature hematopoietic lineages, but they are dispensable for HSCs function. To study the redundant roles of Class 1A PI3K in HSCs, we have generated a triple knockout (TKO) mouse model with conditional deletion of p110α and p110β in hematopoietic cells, and germline deletion of p110δ. Analysis of these TKO mice reveals upon the loss of all three Class1A isoforms causes an increase in HSCs numbers, but decreased self-renewal and differentiation, with inefficient repopulation of all mature blood lineages. This phenotype is different from the phenotypes of any PI3K single isoform knockout mouse model, and even from p110α;δ double knockout animals, suggesting that p110β isoform plays an important compensatory role in HSCs. Moreover, my data suggests that loss of Class I PI3K causes a decrease in autophagy induction upon growth factor deprivation, though autophagy can still be induced with the mTOR inhibitor rapamycin. Thus, I hypothesize that loss of Class IA PI3K compromises autophagy induction, which causes altered HSC metabolism and impaired HSCs fitness. The proposed studies will use our PI3K TKO mouse model to elucidate in Aim 1 the cellular mechanism for defective self-renewal in HSCs. Aim 2 will establish the roles of autophagy in TKO HSC dysfunction. Lastly, Aim 3 will determine which binding interactions of p110β are the most important for its compensatory role in HSC function. In summary, this research will delineate the cellular and molecular mechanisms by which Class 1A PI3K supports HSC self-renewal and differentiation.

提案摘要/摘要成体造血干细胞（HSC）是一种罕见且独特的干细胞群体，存在于造血干细胞中。它们在骨髓中进行自我更新和分化，以维持血液系统。妥善维持自我更新和分化之间的平衡，HSC接收来自生长因子的信号，激活进化上保守的磷酸肌醇3-激酶/蛋白激酶B（PI3 K/AKT）的趋化因子信号通路该途径的病理激活经常在癌症中观察到，包括白血病，使其成为癌症治疗的理想靶点。几种PI3K抑制剂已经用于临床，为了更好地提供治疗靶向信息，了解PI3K在成体HSC中的作用至关重要。造血细胞表达PI3K的三种IA类催化亚型（p110 α、β、δ），所有这些亚型都可以促生长因子和细胞因子信号。在这些亚型中，p110 β是独特的，因为除了p110 β以外，它通过受体酪氨酸激酶（RTK）传递生长因子信号，可直接与G蛋白相互作用偶联受体G β 1亚单位与β 2趋化因子，并结合RAC和RAB 5 GTP酶。在在小鼠胚胎成纤维细胞中，p110 β-RAB 5相互作用被证明对诱导自噬细胞再循环过程，这是必要的维持HSC的代谢和自我，退款单个1A类PI3K同种型在成熟造血谱系中具有独特的功能，但它们在造血干细胞中的表达不稳定。对HSC的功能有影响。为了研究1A类PI 3 K在HSC中的冗余作用，我们有建立了造血细胞中p110 α和p110 β条件性缺失的三重敲除（TKO）小鼠模型，细胞，和p110 δ的种系缺失。对这些TKO小鼠的分析显示，在所有三种1A类基因缺失后，同种型导致HSC数量增加，但自我更新和分化减少，所有成熟血统的繁殖。这种表型不同于任何PI3K单克隆抗体的表型。同种型敲除小鼠模型，甚至来自p110 α; δ双敲除动物，表明p110 β 同种型在HSC中起重要的代偿作用。此外，我的数据表明，I类PI3K的丢失在生长因子缺乏时，自噬诱导减少，尽管自噬仍然可以被抑制。用mTOR抑制剂雷帕霉素诱导。因此，我假设IA类PI3K的丢失会损害自噬诱导，其导致HSC代谢改变和HSC适应性受损。拟议的研究将使用我们的PI3K TKO小鼠模型来阐明Aim 1中的细胞机制造血干细胞自我更新缺陷的原因。目的2：探讨自噬在TKO HSC功能障碍中的作用。最后，目的3将确定p110 β的哪种结合相互作用对于其代偿作用是最重要的。 HSC功能。总之，本研究将阐明细胞和分子机制， PI3K支持HSC自我更新和分化。