Project description:Cellular metabolism is important for adult neural stem/progenitor cell (NSPC) behavior. However, its role in the transition from quiescence to proliferation is not fully understood. We here show that the mitochondrial pyruvate carrier (MPC) plays a crucial and unexpected part in this process. MPC transports pyruvate into mitochondria, linking cytosolic glycolysis to mitochondrial tricarboxylic acid cycle and oxidative phosphorylation. Despite its metabolic key function, the role of MPC in NSPCs has not been addressed. We show that quiescent NSPCs have an active mitochondrial metabolism and express high levels of MPC. Pharmacological MPC inhibition increases aspartate and triggers NSPC activation. Furthermore, genetic Mpc1 ablation in vitro and in vivo also activates NSPCs, which differentiate into mature neurons, leading to overall increased hippocampal neurogenesis in adult and aged mice. These findings highlight the importance of metabolism for NSPC regulation and identify an important pathway through which mitochondrial pyruvate import controls NSPC quiescence and activation.
Project description:Cellular metabolism is important for adult neural stem/progenitor cell (NSPC) behavior. However, its role in the transition from quiescence to proliferation is not fully understood. We here show that the mitochondrial pyruvate carrier (MPC) plays a crucial and unexpected part in this process. MPC transports pyruvate into mitochondria, linking cytosolic glycolysis to mitochondrial tricarboxylic acid cycle and oxidative phosphorylation. Despite its metabolic key function, the role of MPC in NSPCs has not been addressed. We show that quiescent NSPCs have an active mitochondrial metabolism and express high levels of MPC. Pharmacological MPC inhibition increases aspartate and triggers NSPC activation. Furthermore, genetic Mpc1 ablation in vitro and in vivo also activates NSPCs, which differentiate into mature neurons, leading to overall increased hippocampal neurogenesis in adult and aged mice. These findings highlight the importance of metabolism for NSPC regulation and identify an important pathway through which mitochondrial pyruvate import controls NSPC quiescence and activation.
Project description:Neural stem cells were sorted according to their activated or quiescent state by flow cytometry using a set of 3 markers (LeX, CD24 and EGFR) We used microarrays to detail the global programme of gene expression underlying the proliferation/quiescence balance.
Project description:Metabolic flexibility refers to the ability of a tissue to adjust cellular fuel choice in response to conditional changes in metabolic demand and activity. A loss of metabolic flexibility is now recognized as a defining feature of various diseases and cellular dysfunction. In this study, using an inducible, skeletal muscle-specific knockout (KO) mouse, we found microRNA-1 (miR-1), the most abundant microRNA (miRNA) in skeletal muscle, was necessary to maintain whole-body metabolic flexibility. This was demonstrated by a loss of diurnal oscillations in whole-body respiratory exchange ratio and higher fasting blood glucose in miR-1 KO mice. Argonaute 2 enhanced crosslinking and immunoprecipitation sequencing (AGO2 eCLIP-seq) and RNA-seq analyses identified, for the first time, bona fide miR-1 target genes in adult skeletal muscle that regulated pyruvate metabolism. Comprehensive bioenergetic phenotyping combined with skeletal muscle proteomics and metabolomics showed that miR-1 was necessary to maintain metabolic flexibility by regulating pyruvate metabolism through mechanisms including the alternative splicing of pyruvate kinase (Pkm). The loss of metabolic flexibility in the miR-1 KO mouse was rescued by pharmacological inhibition of the miR-1 target, monocarboxylate transporter 4 (MCT4), which redirects glycolytic carbon flux toward oxidation. The maintenance of metabolic flexibility by miR-1 was necessary for sustained endurance activity in mice and in C. elegans. The physiological down-regulation of miR-1 in response to a hypertrophic stimulus in both humans and mice caused a similar metabolic reprogramming necessary for muscle cell growth. Taken together, these data identify a novel post-transcriptional mechanism of whole-body metabolism regulation mediated by a tissue-specific miRNA.
Project description:RNA-sequencing was performed to look for transcriptional differences between wild-type and Mpc2-deficient granulocyte-macrophage progenitors immediately following the deletion of Mpc2. Paper abstract: Hematopoietic stem and progenitor cells likely engage specific metabolic pathways to promote homeostasis of downstream mature lineages. We examined hematopoiesis in mice conditionally deficient in genes required for long-chain fatty acid oxidation (Cpt2), glutaminolysis (Gls), or mitochondrial pyruvate import (Mpc2). Genetic ablation of Cpt2 or Gls minimally impacted most blood lineages. Deletion of Mpc2 led to a sharp decline in mature myeloid cells and a slower reduction in T cells, whereas other hematopoietic lineages were unaffected. Yet MPC2-deficient monocytes and neutrophils rapidly recovered due to a transient increase in proliferation of myeloid but not other progenitors. Competitive bone marrow chimera and stable isotope tracing experiments demonstrated that this proliferative burst was progenitor-intrinsic and accompanied by a metabolic switch to glutaminolysis. Myeloid recovery after loss of MPC2 or cyclophosphamide treatment was delayed in the absence of GLS. Reciprocally, MPC2 was not required for myeloid recovery after cyclophosphamide treatment. Thus, whereas mitochondrial pyruvate metabolism maintains myelopoiesis under steady-state conditions, rapid recovery from acute loss of myeloid cells requires a switch to glutaminolysis in progenitors.
Project description:The transition between quiescence and activation in neural stem and progenitor cells (NSPCs) is coupled to reversible changes in energy metabolism with key implications for life-long NSPC self-renewal and neurogenesis. How this metabolic plasticity is ensured between NSPC activity states is unclear. We find that a state-specific rewiring of the mitochondrial proteome by the i-AAA peptidase YME1L is required to preserve NSPC self-renewal. YME1L controls the abundance of numerous mitochondrial substrates in quiescent NSPCs, and its deletion activates a differentiation program characterized by broad metabolic changes causing the irreversible shift away from a fatty acid oxidation-dependent state. Conditional Yme1l deletion in adult NSPCs in vivo results in defective self-renewal and premature differentiation, ultimately leading to NSPC pool depletion. Our results disclose an important role for YME1L in coordinating the switch between metabolic states of NSPCs and suggest that NSPC fate is regulated by compartmentalized changes in protein network dynamics.