The intermediate conductance, Ca2+-activated K+ channel (KCa3.1) targets to the basolateral (BL) membrane in polarized epithelia where it plays a key role in transepithelial ion transport. However, there are no studies defining the anterograde and retrograde trafficking of KCa3.1 in polarized epithelia. Herein, we utilize Biotin Ligase Acceptor Peptide (BLAP)-tagged KCa3.1 to address these trafficking steps in polarized epithelia, using MDCK, Caco-2 and FRT cells. We demonstrate that KCa3.1 is exclusively targeted to the BL membrane in these cells when grown on filter supports. Following endocytosis, KCa3.1 degradation is prevented by inhibition of lysosomal/proteosomal pathways. Further, the ubiquitylation of KCa3.1 is increased following endocytosis from the BL membrane and PR-619, a deubiquitylase inhibitor, prevents degradation, indicating KCa3.1 is targeted for degradation by ubiquitylation. We demonstrate that KCa3.1 is targeted to the BL membrane in polarized LLC-PK1 cells which lack the μ1B subunit of the AP-1 complex, indicating BL targeting of KCa3.1 is independent of μ1B. As Rabs 1, 2, 6 and 8 play roles in ER/Golgi exit and trafficking of proteins to the BL membrane, we evaluated the role of these Rabs in the trafficking of KCa3.1. In the presence of dominant negative Rab1 or Rab8, KCa3.1 cell surface expression was significantly reduced, whereas Rabs 2 and 6 had no effect. We also co-immunoprecipitated KCa3.1 with both Rab1 and Rab8. These results suggest these Rabs are necessary for the anterograde trafficking of KCa3.1. Finally, we determined whether KCa3.1 traffics directly to the BL membrane or through recycling endosomes in MDCK cells. For these studies, we used either recycling endosome ablation or dominant negative RME-1 constructs and determined that KCa3.1 is trafficked directly to the BL membrane rather than via recycling endosomes. These results are the first to describe the anterograde and retrograde trafficking of KCa3.1 in polarized epithelia cells.

Multifunctional nanoparticles are increasingly employed to improve biological efficiency in medical imaging, diagnostics, and treatment applications. However, even the most well-established nanoparticle platforms rely on multiple-step wet-chemistry approaches for functionalization often with linkers, substantially increasing complexity and cost, while limiting efficacy. Plasma dust nanoparticles are ubiquitous in space, commonly observed in reactive plasmas, and long regarded as detrimental to many manufacturing processes. As the bulk of research to date has sought to eliminate plasma nanoparticles, their potential in theranostics has been overlooked. Here we show that carbon-activated plasma-polymerized nanoparticles (nanoP 3 ) can be synthesized in dusty plasmas with tailored properties, in a process that is compatible with scale up to high throughput, low-cost commercial production. We demonstrate that nanoP 3 have a long active shelf life, containing a reservoir of long-lived radicals embedded during their synthesis that facilitate attachment of molecules upon contact with the nanoparticle surface. Following synthesis, nanoP 3 are transferred to the bench, where simple one-step incubation in aqueous solution, without the need for intermediate chemical linkers or purification steps, immobilizes multiple cargo that retain biological activity. Bare nanoP 3 readily enter multiple cell types and do not inhibit cell proliferation. Following functionalization with multiple fluorescently labeled cargo, nanoP 3 retain their ability to cross the cell membrane. This paper shows the unanticipated potential of carbonaceous plasma dust for theranostics, facilitating simultaneous imaging and cargo delivery on an easily customizable, functionalizable, cost-effective, and scalable nanoparticle platform.

Visual Abstract

Visual AbstractElectrospinning of silk to create nanofibers, which deposit onto a rotating collector. This results in the formation of a pure silk conduit of 1.5 mm internal diameter. These conduits are then implanted into the descending abdominal aorta of Sprague Dawley Rats with end-to-end suturing, and left for 3, 6, 12, and 24 weeks. Endpoint histologic analysis of the explanted grafts demonstrate hyperplasia stabilization, complete endothelialization and excellent blood compatibility.