We describe the fabrication and characterization of tungsten oxide nanofibers using the electrospinning technique and sol-gel chemistry. Tungsten isopropoxide sol-gel precursor was incorporated into poly(vinyl acetate)(PVAc)/DMF solutions and electrospun to form composite nanofibers. The as-spun composite nanofibers were subsequently calcinated to obtain pure tungsten oxide nanofibers with controllable diameters of around 100 nm. SEM and TEM were utilized to investigate the structure and morphology of tungsten oxide nanofibers before and after calcination. The relationship between solution concentration and ceramic nanofiber morphology has been studied. A synchrotron-based in situ XRD method was employed to study the dynamic structure evolution of the tungsten oxide nanofibers during the calcination process. It has been shown that the as-prepared tungsten oxide ceramic nanofibers have a quick response to ammonia with various concentrations, suggesting potential applications of the electrospun tungsten oxide nanofibers as a sensor material for gas detection.

SUMMARY AMPA receptors (AMPARs) mediate fast excitatory synaptic transmission and are crucial for synaptic plasticity, learning and memory. However, the molecular control of AMPAR stability and its neurophysiological significance remain unclear. Here we report that AMPARs are subject to lysine acetylation at their C-termini. Acetylation reduces AMPAR internalization and degradation, leading to increased cell-surface localization and prolonged receptor half-life. Through competition for the same lysine residues, acetylation intensity is inversely related to the levels of AMPAR ubiquitination. We find that sirtuin 2 (SIRT2) acts as an AMPAR deacetylase regulating AMPAR trafficking and proteostasis. SIRT2 knockout mice (Sirt2−/−) show marked up-regulation in AMPAR acetylation and protein accumulation. Both Sirt2−/− mice and mice expressing acetylation mimetic GluA1 show aberrant synaptic plasticity, accompanied with impaired learning and memory. These findings establish SIRT2-regulated lysine acetylation as a form of AMPAR post-translational modification that regulates its turnover, as well as synaptic plasticity and cognitive function.

BACKGROUND: Previous studies suggested that mdivi-1 (mitochondrial division inhibitor), a putative inhibitor of dynamin-related protein (DRP1), decreased cancer cell proliferation through inducing mitochondrial fusion and altering oxygen consumption. However, the metabolic reprogramming underlying the DRP1 inhibition is still unclear in cancer cells. METHODS: To better understand the metabolic effect of DRP1 inhibition, [U-13 C]glucose isotope tracing was employed to assess mdivi-1 effects in several cancer cell lines, DRP1-WT (wild-type) and DRP1-KO (knockout) H460 lung cancer cells and mouse embryonic fibroblasts (MEFs). RESULTS: Mitochondrial staining confirmed that mdivi-1 treatment and DRP1 deficiency induced mitochondrial fusion. Surprisingly, metabolic isotope tracing found that mdivi-1 decreased mitochondrial oxidative metabolism in the lung cancer cell lines H460, A549 and the colon cancer cell line HCT116. [U-13 C]glucose tracing studies also showed that the TCA cycle intermediates had significantly lower enrichment in mdivi-1-treated cells. In comparison, DRP1-WT and DRP1-KO H460 cells had similar oxidative metabolism, which was decreased by mdivi-1 treatment. Furthermore, mdivi-1-mediated effects on oxidative metabolism were independent of mitochondrial fusion. CONCLUSIONS: Our data suggest that, in cancer cells, mdivi-1, a putative inhibitor of DRP1, decreases oxidative metabolism to impair cell proliferation.