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NAMPT-mediated salvage synthesis of NAD+ controls morphofunctional changes of macrophages.

ABSTRACT: Functional morphodynamic behavior of differentiated macrophages is strongly controlled by actin cytoskeleton rearrangements, a process in which also metabolic cofactors ATP and NAD(H) (i.e. NAD+ and NADH) and NADP(H) (i.e. NADP+ and NADPH) play an essential role. Whereas the link to intracellular ATP availability has been studied extensively, much less is known about the relationship between actin cytoskeleton dynamics and intracellular redox state and NAD+-supply. Here, we focus on the role of nicotinamide phosphoribosyltransferase (NAMPT), found in extracellular form as a cytokine and growth factor, and in intracellular form as one of the key enzymes for the production of NAD+ in macrophages. Inhibition of NAD+ salvage synthesis by the NAMPT-specific drug FK866 caused a decrease in cytosolic NAD+ levels in RAW 264.7 and Maf-DKO macrophages and led to significant downregulation of the glycolytic flux without directly affecting cell viability, proliferation, ATP production capacity or mitochondrial respiratory activity. Concomitant with these differential metabolic changes, the capacity for phagocytic ingestion of particles and also substrate adhesion of macrophages were altered. Depletion of cytoplasmic NAD+ induced cell-morphological changes and impaired early adhesion in phagocytosis of zymosan particles as well as spreading performance. Restoration of NAD+ levels by NAD+, NMN, or NADP+ supplementation reversed the inhibitory effects of FK866. We conclude that direct coupling to local, actin-based, cytoskeletal dynamics is an important aspect of NAD+'s cytosolic role in the regulation of morphofunctional characteristics of macrophages.

SUBMITTER: Venter G

PROVIDER: S-EPMC4019579 | biostudies-literature | 2014

REPOSITORIES: biostudies-literature

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NAMPT-mediated salvage synthesis of NAD+ controls morphofunctional changes of macrophages.

Venter Gerda G Oerlemans Frank T J J FT Willemse Marieke M Wijers Mietske M Fransen Jack A M JA Wieringa Bé B

PloS one 20140513 5

Functional morphodynamic behavior of differentiated macrophages is strongly controlled by actin cytoskeleton rearrangements, a process in which also metabolic cofactors ATP and NAD(H) (i.e. NAD+ and NADH) and NADP(H) (i.e. NADP+ and NADPH) play an essential role. Whereas the link to intracellular ATP availability has been studied extensively, much less is known about the relationship between actin cytoskeleton dynamics and intracellular redox state and NAD+-supply. Here, we focus on the role of ...[more]

PMID: 24824795

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Project description:Abstract BACKGROUND Current treatment of glioblastoma (GBM) with surgery and chemoRT yields an average survival of ~1.5 years, highlighting the need for more effective therapies. We have previously reported that PAK4 is a key modulator of radioresistance in GBM. Additionally, pathways that regulate differential energy metabolism in gliomas and circumvent tumor heterogeneity have recently emerged as promising therapeutic targets. We hypothesized that inhibition of NAMPT, the rate-limiting enzyme of the NAD+ salvage pathway, a key pathway preferentially used in glioma energy metabolism, would be effective against GBM. METHODS We tested the efficacy of KPT9274, a potent first-in-class dual inhibitor of PAK4 and NAMPT, currently in human trials against solid tumors and lymphomas (NCT02702492), on NAD levels and cell viability in glioma cell lines and patient-derived glioma stem-like cells (GSC). We also examined enzyme-kinetics of various components of the NAD salvage pathway and effects of NADH rescue by nicotinamide, NMN and NAD. Lastly, we examined the biological relevance of NAMPT inhibition in glioma cells and GSC using a combination of cell adhesion, wound-healing, transwell-migration and microtubule formation assays. RESULTS Treatment with KPT9274 resulted in potent depletion of NAD in glioma cells which was rescued by nicotinamide, NMN and NAD demonstrating its specificity against NAMPT. KPT-9274 treatment resulted in potent inhibition of cell adhesion, migration, cell invasion, endothelial tube formation and proliferation in glioma cells and GSC. In vivo studies in mouse bioluminescent intracranial glioma PDX model as well as PK studies are ongoing to confirm the pre-clinical significance of targeting NAMPT in gliomas and will be presented. CONCLUSIONS Our study demonstrates a key role for NAMPT in NAD generation in gliomas as seen by the potent biological effects of KPT-9274 against these tumors and supports the potential for targeting the NAD salvage pathway as a novel therapeutic strategy for treatment of GBM.

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NAMPT-mediated salvage synthesis of NAD+ controls morphofunctional changes of macrophages.

Publications

NAMPT-mediated salvage synthesis of NAD+ controls morphofunctional changes of macrophages.

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