White NM, Jiang D, Burgess JD, Bederman IR, Previs SF, Kelley TJ. Altered cholesterol homeostasis in cultured and in vivo models of cystic fibrosis.

The voltammetry of cytochrome c oxidase immobilized in lipid bilayer membranes on gold electrodes and amperometric data of cytochrome c reacting at these electrodes under flow conditions are reported. A submonolayer of octadecyl mercaptan formed on electrodeposited silver anchors and becomes a part of the lipid bilayer membrane on the gold electrode. The supported lipid bilayer membrane containing cytochrome c oxidase is formed during a deoxycholate dialysis procedure. Slow scan rate cyclic voltammograms (20 mV/s) taken at the oxidase-modified electrodes show well-defined anodic waves. Fast scan rate cyclic voltammograms (200 mV/s) taken at the oxidase-modified electrodes show well-defined anodic and cathodic waves. Cyclic voltammograms taken at the oxidase-modified electrodes under 0.1 mM sodium cyanide show an increase (ca. 300%) in electrode capacitance and well-defined anodic and cathodic waves irrespective of scan rate. The voltammetric data are consistent with electron transfer of cytochrome c oxidase coupled with changes in nonfaradaic current and possibly diffusion of cytochrome c oxidase in a lipid multilayer structure. Quartz crystal microbalance data of cytochrome c binding to lipid bilayer membranes containing no cytochrome c oxidase under flow conditions are presented.

Dysfunctional cystic fibrosis transmembrane conductance regulator (CFTR) leads to many cellular consequences, including perinuclear accumulation of free cholesterol due to impaired endosomal transport. The hypothesis being tested is that CF-related perinuclear cholesterol accumulation due to disrupted endocytic trafficking occurs as a result of reduced microtubule (MT) acetylation. Here, it is identified that acetylated-α-tubulin (Ac-tub) content is reduced by ∼40% compared with respective wild-type controls in both cultured CF cell models (IB3) and primary Cftr-/- mouse nasal epithelial tissue. Histone deacetylase 6 (HDAC6) has been shown to regulate MT acetylation, which provides reasonable grounds to test its impact on reduced Ac-tub content on CF cellular phenotypes. Inhibition of HDAC6, either through tubastatin treatment or HDAC6 knockdown in CF cells, increases Ac-tub content and results in redistributed free cholesterol and reduced stimulation of NF-κB activity. Mechanistically, endoplasmic reticulum stress, which is widely reported in CF and leads to aggresome formation, is identified as a regulator of MT acetylation. F508del CFTR correction with C18 in primary airway epithelial cells restores MT acetylation and cholesterol transport. A significant role for phosphatidyl inositol-3 kinase p110α is also identified as a regulator of MT acetylation.

SignificanceThe quantification of protein activity in individual lysosomes in living cells is realized using a nanocapillary designed to electrochemically analyze internal solution, in which a single lysosome is sorted from the cell and the target protein is reacted with the corresponding kit components to generate hydrogen peroxide for measurement. The ability to sort and assay multiple lysosomes from the same cell allows direct study of protein function at subcellular resolution and provides unprecedented information about the homogeneity within the lysosomal population of a single cell.

Size, shape, and compositional control are at the heart of nanochemistry.[1] Herein, we present a novel method that allows control over all three variables in a simple one-step, wet-chemical procedure. One-dimensional (1D) nanomaterials are of great interest for the construction of highperformance thermoelectric (TE) devices. Theoretical calculations indicate that improvement in TE efficiency can be achieved as the diameter of the 1D structures approaches a few nanometers. [2,3] To date, the most successful synthesis of 1D TE materials has been achieved by electrodeposition within alumina templates. A series of Bi 2 Te 3 , [4,5] Bi 2Àx Sb x Te 3 , [6] Bi 2 Te 3Ày Se y , [7] and Bi 1Àx Sb x [8,9] nanowires were prepared by using the template-based method. The advantages of the electrodeposition method include high efficiency, ease of control over composition, highly crystalline products, and room-temperature reaction conditions. However, the diameters of the nanowires synthesized by the template method are well above 10 nm. To get into the sub-10-nm regime, one needs to obtain templates with very narrow channel diameters, which is currently the limiting factor of this technique.However, advances in combining sonochemistry and electrochemistry have provided a new strategy for the synthesis of nanomaterials. [10][11][12][13] The synthesis of quite sophisticated 1D nanomaterials has recently been demonstrated [14] to be possible through careful control of the electrochemistry, sonochemistry, and initial composition of the precursor solutions. As observed, the advantage of the sonoelectrochemical method is that it achieves 1D control without any template, thereby practically overcoming the limitation of generating nanorods with diameters below 10 nm. This diameter is the size regime in which TE properties become enhanced and a controlled synthesis can produce technologically relevant nanomaterials. Herein, we report the first synthesis of monodispersed PbTe nanorods that are sub-10 nm in diameter through a sonoelectrochemical technique.Furthermore, we present the effect of changing the concentration of the coordinating ligand on the resulting composition of the synthesized nanomaterials. Changing the metal/ ligand ratio enabled us to tune the composition of the product from pure Te to pure PbTe nanorods.Lead telluride is the material of choice because of its great potential in high-performance TE devices.[15] Furthermore, it allows the mechanisms that lead to control over the resulting nanorod size and composition to be studied. Basically, the synthesis of PbTe nanorods consists of two steps: First, the electrodeposition of PbTe on the surface of the Ti sonication horn, and second, the dispersion of the PbTe nuclei into solution by pulsed sonication. Control over the electrodeposition process is crucial in obtaining pure and highly crystalline PbTe nanoparticles. Interestingly, we found that the Pb 2+