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Adenylate Kinase 2 Deficiency and the Failure of Myelopoiesis

腺苷酸激酶 2 缺乏和骨髓生成失败

基本信息

批准号：
10583534
负责人：
Katja Gabriele Weinacht
金额：
$ 58.48万
依托单位：
STANFORD UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2022
资助国家：
美国
起止时间：
2022-04-01 至 2027-03-31
项目状态：
未结题

来源：
https://reporter.nih.gov/project-details/10583534
关键词：
ATP Synthesis Pathway Adenine Nucleotides Adult Affect Alleles Aspartate B-Lymphocytes Blood Carbon Carnitine Catabolism Cell Cycle Cells Citric Acid Cycle Clustered Regularly Interspaced Short Palindromic Repeats Cytoplasm Deamination Defect Development Electrons Energy Metabolism Enzymes Erythroid Excretory function Exhibits FRAP1 gene Failure Generations Genetic Transcription Hematological Disease Hematopoietic Hematopoietic Stem Cell Transplantation Hematopoietic stem cells Homeostasis Human Image Impairment In Vitro Inosine Monophosphate Isotopes Knock-out Life Link Lipids Loss of Heterozygosity Lymphopenia Mass Spectrum Analysis Mediating Megakaryocytes Metabolic Metabolic Diseases Mitochondria Mitochondrial Diseases Modeling Mus Myelogenous Myeloid Cells Myelopoiesis NADH NADH oxidase Natural regeneration Neutropenia Nucleoside Hydrolases Nucleotides Oxidation-Reduction Pathology Pathway interactions Patients Phenotype Phosphorylation Proliferating Purines Pyruvate Recycling Ribosomal RNA Ribosomes Severe Combined Immunodeficiency Signal Transduction Stress System T-Lymphocyte Testing Therapeutic immunosuppression Translations Transplantation Xenograft procedure adenylate kinase cancer therapy cell type improved in vitro Model in vivo in vivo Model insight loss of function mutation metabolomics mitochondrial metabolism novel novel strategies nucleotide metabolism overexpression progenitor purine metabolism reticular dysgenesis stem

项目摘要

PROJECT SUMMARY/ABSTRACT Cellular ATP demand and mitochondrial ATP synthesis are tightly linked. ATP synthesis, in turn, depends on (1) NADH generation in the TCA cycle and (2) recycling of the adenine nucleotide pool. When ATP is depleted and AMP rises, the cell increases energy generation and curtails energy expenditure until homeostasis is restored. In the context of mitochondrial pathology, the system becomes unhinged… Reticular Dysgenesis (RD) is a rare hematologic disease, caused by biallelic loss-of-function mutations in the mitochondrial enzyme Adenylate Kinase 2 (AK2). AK2 catalyzes the phosphorylation of AMP to ADP in the inter-membrane space to generate substrate for ATP synthesis1. RD patients suffer from severe congenital neutropenia, lymphopenia, and die early in life unless cured by hematopoietic stem cell transplantation5. We have developed a novel biallelic CRISPR-knockout model of AK2 in primary human hematopoietic stem and progenitor cells to precisely mimic the failure of human myelopoiesis in culture and after transplantation into mice. Using broad metabolomic profiling, our preliminary studies revealed that AK2-deficient myeloid progenitors exhibit a high NADH/NAD+ ratio and NAD+ depletion, consistent with reductive stress. In addition, AK2-deficient myeloid progenitors displayed a decrease in mitochondrial metabolites, including TCA cycle intermediaries and aspartate, while lipid carnitines were increased, and lipid droplets were found in the cytoplasm. We also detected highly elevated levels of the purine intermediate inosine monophosphate (IMP) and a decrease in rRNA and ribosome subunits. Interestingly, our studies suggest the high IMP stems from deamination of AMP, rather than a block in purine de novo synthesis. Taken together, these observations raise the possibility that AK2 deficiency causes mitochondrial reductive stress, curtailing TCA cycle activity and diverting carbon and electron pools into lipid synthesis while counteracting the accumulation of AMP. These findings led us to hypothesize that AK2 deficiency causes two interconnected but distinct pathologies: I. Reductive stress redirecting energy metabolism into lipid storage rather than OXPHOS; II. Accumulation of AMP and IMP, leading to defects in nucleotide metabolism. Our proposed studies will test if failure of myelopoiesis is primarily a result of reductive stress and impaired energy utilization, versus impaired purine metabolism, or both. We will determine if myelopoiesis can be rescued by correcting the NADH/NAD+ ratio or nucleotide pools. Lastly, we will validate our findings in an in vivo model of RD and investigate if different compensatory mechanisms in different blood lineages result in the RD phenotype. We use RD as a model to dissect escape mechanisms at the juncture of energy metabolism, redox stress, and nucleotide homeostasis. These insights will advance therapies for mitigating reductive stress and using cell type-specific manipulation of purine metabolism as a strategy for immunosuppression and cancer therapy.

项目总结/文摘