Essential functions of mosquito ecdysone importers in development and reproduction

ABSTRACTThe primary insect steroid hormone ecdysone requires a membrane transporter to enter its target cells. Although an organic anion-transporting polypeptide (OATP) named Ecdysone Importer (EcI) serves this role in the fruit fly Drosophila melanogaster and most likely in other arthropod species, this highly conserved transporter is apparently missing in mosquitoes. Here we report three additional OATPs that facilitate cellular incorporation of ecdysone in Drosophila and the yellow fever mosquito Aedes aegypti. These additional ecdysone importers (EcI-2, 3, and 4) are dispensable for development and reproduction in Drosophila, consistent with the predominant role of EcI. In contrast, in Aedes, EcI-2 is indispensable for ecdysone-mediated development, whereas EcI-4 is critical for vitellogenesis induced by ecdysone in adult females. Altogether, our results indicate unique and essential functions of these additional ecdysone importers in mosquito development and reproduction, making them attractive molecular targets for species- and stage-specific control of ecdysone signaling in mosquitoes.

Onion (Allium cepa L.)-Derived Nanoparticles Inhibited LPS-Induced Nitrate Production, however, Their Intracellular Incorporation by Endocytosis Was Not Involved in this Effect on RAW264 Cells

The aim of this study was to evaluate the involvement of nanoparticles prepared from Allium cepa L. as anti-inflammatory agents. In the present study, we identified nanoparticles from Allium cepa L. using the ultracentrifugation exosome purification method. The nanoparticles were referred to as 17,000× g and 200,000× g precipitates, and they contained quercetins, proteins, lipids, and small-sized RNA. The nanoparticles inhibited nitric oxide production from lipopolysaccharide (LPS)-stimulated RAW264 cells without cytotoxic properties. Cellular incorporation was confirmed by laser microscopic observation after PKH26 staining. The inhibition of caveolae-dependent endocytosis and macropinocytosis significantly prevented the incorporation of the nanoparticles but had no effect on the inhibition of nitric oxide in RAW264 cells. Collectively, the identified nanoparticles were capable of inhibiting the LPS response via extracellular mechanisms. Taken together, the way of consuming Allium cepa L. without collapsing the nanoparticles is expected to provide an efficient anti-inflammatory effect.

Peroxynitrite Production Induced by LPS and X-ray Treatment Enhances Cellular Incorporation of Porphyrin in Mouse RAW264 Macrophages

Photodynamic therapy (PDT) is a minimally invasive cancer therapy that combines the accumulation of photosensitizers such as porphyrins in cancer cells with laser irradiation. I have previously reported that mitochondrially derived reactive oxygen species (ROS) regulate the expression of a porphyrin transporter, heme carrier protein 1 (HCP1), and increase porphyrin accumulation in cancer cells. Tumors that contain activated macrophages, referred to as tumor-associated macrophages (TAMs), have been reported to have increased malignancy. TAMs produce nitric oxide (NO), via the expression of inducible NO synthase (iNOS), and the highly reactive nitrogen species, peroxynitrite, which is produced by the reaction of NO with superoxide. Here, I examined the relationship between peroxynitrite, HCP1 expression, and intracellular porphyrin uptake in the murine macrophage cell line RAW264. RAW264 cells were activated by lipopolysaccharide (LPS) treatment which resulted in increased iNOS expression and NO production. Additional X-ray irradiation resulted in the generation of ROS and the subsequent generation of peroxynitrite. Importantly, LPS and X-ray co-treatment significantly enhanced HCP1 expression and porphyrin accumulation in cells, suggesting that the peroxynitrite upregulates the porphyrin transporter, HCP1. Therefore, TAMs may be effectively targeted with PDT, and tumor progression may be suppressed in general by agents that target the activation of macrophages.