RESUMO
An amendment to this paper has been published and can be accessed via a link at the top of the paper.
RESUMO
Vascular endothelial cell (EC) dysfunction plays a key role in diabetic complications. This study discovers significant upregulation of Quaking-7 (QKI-7) in iPS cell-derived ECs when exposed to hyperglycemia, and in human iPS-ECs from diabetic patients. QKI-7 is also highly expressed in human coronary arterial ECs from diabetic donors, and on blood vessels from diabetic critical limb ischemia patients undergoing a lower-limb amputation. QKI-7 expression is tightly controlled by RNA splicing factors CUG-BP and hnRNPM through direct binding. QKI-7 upregulation is correlated with disrupted cell barrier, compromised angiogenesis and enhanced monocyte adhesion. RNA immunoprecipitation (RIP) and mRNA-decay assays reveal that QKI-7 binds and promotes mRNA degradation of downstream targets CD144, Neuroligin 1 (NLGN1), and TNF-α-stimulated gene/protein 6 (TSG-6). When hindlimb ischemia is induced in diabetic mice and QKI-7 is knocked-down in vivo in ECs, reperfusion and blood flow recovery are markedly promoted. Manipulation of QKI-7 represents a promising strategy for the treatment of diabetic vascular complications.
Assuntos
Diabetes Mellitus Experimental/patologia , Células Endoteliais/metabolismo , Proteínas de Ligação a RNA/antagonistas & inibidores , Proteínas de Ligação a RNA/metabolismo , Doenças Vasculares/patologia , Animais , Antígenos CD/genética , Aterosclerose/patologia , Caderinas/genética , Moléculas de Adesão Celular/genética , Moléculas de Adesão Celular Neuronais/genética , Células Cultivadas , Regulação da Expressão Gênica/genética , Humanos , Hiperglicemia/patologia , Isquemia/patologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Interferência de RNA , RNA Mensageiro/genética , RNA Interferente Pequeno/genética , Proteínas de Ligação a RNA/genéticaRESUMO
Strict regulation of stem cell metabolism is essential for tissue functions and tumor suppression. In this study, we investigated the role of fumarate hydratase (Fh1), a key component of the mitochondrial tricarboxylic acid (TCA) cycle and cytosolic fumarate metabolism, in normal and leukemic hematopoiesis. Hematopoiesis-specific Fh1 deletion (resulting in endogenous fumarate accumulation and a genetic TCA cycle block reflected by decreased maximal mitochondrial respiration) caused lethal fetal liver hematopoietic defects and hematopoietic stem cell (HSC) failure. Reexpression of extramitochondrial Fh1 (which normalized fumarate levels but not maximal mitochondrial respiration) rescued these phenotypes, indicating the causal role of cellular fumarate accumulation. However, HSCs lacking mitochondrial Fh1 (which had normal fumarate levels but defective maximal mitochondrial respiration) failed to self-renew and displayed lymphoid differentiation defects. In contrast, leukemia-initiating cells lacking mitochondrial Fh1 efficiently propagated Meis1/Hoxa9-driven leukemia. Thus, we identify novel roles for fumarate metabolism in HSC maintenance and hematopoietic differentiation and reveal a differential requirement for mitochondrial Fh1 in normal hematopoiesis and leukemia propagation.
Assuntos
Fumarato Hidratase/fisiologia , Células-Tronco Hematopoéticas/fisiologia , Animais , Feminino , Fumaratos/metabolismo , Hematopoese , Histonas/metabolismo , Leucemia Mieloide Aguda/etiologia , Camundongos , Camundongos Endogâmicos C57BL , Mitocôndrias/metabolismo , Fator 2 Relacionado a NF-E2/fisiologia , Consumo de OxigênioRESUMO
Accurate monitoring of tumor dynamics and leukemic stem cell (LSC) heterogeneity is important for the development of personalized cancer therapies. In this study, we experimentally induced distinct types of leukemia in mice by enforced expression of Cbx7. Simultaneous cellular barcoding allowed for thorough analysis of leukemias at the clonal level and revealed high and unpredictable tumor complexity. Multiple LSC clones with distinct leukemic properties coexisted. Some of these clones remained dormant but bore leukemic potential, as they progressed to full-blown leukemia after challenge. LSC clones could retain multilineage differentiation capacities, where one clone induced phenotypically distinct leukemias. Beyond a detailed insight into CBX7-driven leukemic biology, our model is of general relevance for the understanding of tumor dynamics and clonal evolution.
