Highly reactive layer-by-layer (LbL) films have been developed as protective coatings intended for application on fibers worn by military personnel. In this work, the anionic species are titanium dioxide nanoparticles ranging from 5 to 10 nm in size, which are prepared in a stable colloidal solution specifically designed for this application, while the cationic species can be one of several traditional synthetic polycations, including weak and strong polyelectrolytes. The resulting coatings are mechanically stable and offer selective protection when the wearer is exposed to UV radiation (e.g.,sunlight); whereas the inherent water transmissive nature of the multilayers allows for much greater water vapor transport rates as compared to an inert rubber barrier material. Permeation tests of coated materials were conducted in a specially engineered cell by exposing the materials to a CWA simulant. In the extreme case, when a coated material is subjected to a saturated vapor of the CWA simulant, UV exposure resulted in a 95% decrease in toxic agent permeation. Furthermore, the coating can be deposited via a spray-LbL technique developed specifically for rapid, uniform deposition over large areas of textile materials at ambient temperatures and moderate pressures.

Stimulation of Na+/K+-ATPase activity in alveolar epithelial cells by cAMP involves its recruitment from intracellular compartments to the plasma membrane. Here, we studied the role of the actin molecular motor myosin-V in this process. We provide evidence that, in alveolar epithelial cells, cAMP promotes Na+/K+-ATPase recruitment to the plasma membrane by increasing the average speed of Na+/K+-ATPase-containing vesicles moving to the cell periphery. We found that three isoforms of myosin-V are expressed in alveolar epithelial cells; however, only myosin-Va and Vc colocalized with the Na+/K+-ATPase in intracellular membrane fractions. Overexpression of dominant-negative myosin-Va or knockdown with specific shRNA increased the average speed and distance traveled by the Na+/K+-ATPase-containing vesicles, as well as the Na+/K+-ATPase activity and protein abundance at the plasma membrane to similar levels as those observed with cAMP stimulation. These data show that myosin-Va has a role in restraining Na+/K+-ATPase-containing vesicles within intracellular pools and that this restrain is released after stimulation by cAMP allowing the recruitment of the Na+/K+-ATPase to the plasma membrane and thus increased activity.

Recruitment of the Na,K-ATPase to the plasma membrane of alveolar epithelial cells results in increased active Na(+) transport and fluid clearance in a process that requires an intact microtubule network. However, the microtubule motors involved in this process have not been identified. In the present report, we studied the role of kinesin-1, a plus-end microtubule molecular motor that has been implicated in the movement of organelles in the Na,K-ATPase traffic. We determined by confocal microscopy and biochemical assays that kinesin-1 and the Na,K-ATPase are present in the same membranous cellular compartment. Knockdown of kinesin-1 heavy chain (KHC) or the light chain-2 (KLC2), but not of the light chain-1 (KLC1), decreased the movement of Na,K-ATPase-containing vesicles when compared to sham siRNA-transfected cells (control group). Thus, a specific isoform of kinesin-1 is required for microtubule-dependent recruitment of Na,K-ATPase to the plasma membrane, which is of physiological significance.

Cancer cell-derived micro-particles (MPs) play important regulatory roles on cellular and system levels. These activities are attributed in part to protein factors carried by MPs. However, recruitment strategies for sequestering certain protein factors in MPs are poorly understood. In the current study, using exogenous and endogenously expressed phospholipid-binding probes, we investigated the distribution of membrane phospholipids in MPs as a potential mechanism for electrostatically enriching cationic protein factors in MPs. We detected a significant level of externalised phosphatidylethanolamine (PE) at the outer surface of MPs. This was accompanied, in the inner leaflet of the MP membrane, by a greater density of negatively charged phospholipids, particularly phosphatidylserine (PS). The local enrichment of PS in the inner surface of MPs was correlated with an elevated presence of small GTPases in a polybasic region (PBR)-dependent fashion. By employing a series of RhoA derivatives, including constitutively active and RhoA derivatives lacking a PBR, we could demonstrate that the congregation of RhoA in MPs was dependent on the presence of the PBR. A chimer with the fusion of PBR sequence alone to GFP significantly enhanced GFP localisation in MPs, indicative of a positive contribution of electrostatic interactions in RhoA recruitment to MPs. Using in silico thermodynamic simulations, we characterised the electrostatic interactions between PBR and anionic lipid membrane surface. In summary, the redistribution of membrane phospholipids in MPs has an impact on the local ionic density, and is likely a contributing factor in the electrostatic recruitment of membrane-associated proteins to MPs in a PBR-dependent fashion.

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