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Mascuch, SJ, Boudreau PD, Carland TM, Pierce NT, Olson J, Hensler ME, Choi H, Campanale J, Hamdoun A, Nizet V, Gerwick WH, Gaasterland T, Gerwick L.  2018.  Marine natural product honaucin A attenuates inflammation by activating the Nrf2-ARE pathway. Journal of Natural Products. 81:506-514.   10.1021/acs.jnatprod.7b00734   AbstractWebsite

The cyanobacterial marine natural product honaucin A inhibits mammalian innate inflammation in vitro and in vivo. To decipher its mechanism of action, RNA sequencing was used to evaluate differences in gene expression of cultured macrophages following honaucin A treatment. This analysis led to the hypothesis that honaucin A exerts its anti-inflammatory activity through activation of the cytoprotective nuclear erythroid 2-related factor 2 (Nrf2)-antioxidant response element/electrophile response element (ARE/EpRE) signaling pathway. Activation of this pathway by honaucin A in cultured human MCF7 cells was confirmed using an Nrf2 luciferase reporter assay. In vitro alkylation experiments with the natural product and N-acetyl-L-cysteine suggest that honaucin A activates this pathway through covalent interaction with the sulfhydryl residues of the cytosolic repressor protein Keapl. Honaucin A presents a potential therapeutic lead for diseases with an inflammatory component modulated by Nrf2-ARE.

Nicklisch, SCT, Bonito LT, Sandin S, Hamdoun A.  2017.  Mercury levels of yellowfin tuna (Thunnus albacares) are associated with capture location. Environmental Pollution. 229:87-93.   10.1016/j.envpol.2017.05.070   AbstractWebsite

Mercury is a toxic compound to which humans are exposed by consumption of fish. Current fish consumption advisories focus on minimizing the risk posed by the species that are most likely to have high levels of mercury. Less accounted for is the variation within species, and the potential role of the geographic origin of a fish in determining its mercury level. Here we surveyed the mercury levels in 117 yellowfin tuna caught from 12 different locations worldwide. Our results indicated significant variation in yellowfin tuna methylmercury load, with levels that ranged from 0.03 to 0.82 mu g/g wet weight across individual fish. Mean mercury levels were only weakly associated with fish size (R-2 < 0.1461) or lipid content (R-2 < 0.00007) but varied significantly, by a factor of 8, between sites. The results indicate that the geographic origin of fish can govern mercury load, and argue for better traceability of fish to improve the accuracy of exposure risk predictions. (C)2017 Elsevier Ltd. All rights reserved.

Campanale, JP, Gokirmak T, Espinoza JA, Oulhen N, Wessel GM, Hamdoun A.  2014.  Migration of sea urchin primordial germ cells. Developmental Dynamics. 243:917-927.   10.1002/dvdy.24133   AbstractWebsite

Background: Small micromeres are produced at the fifth cleavage of sea urchin development. They express markers of primordial germ cells (PGCs), and are required for the production of gametes. In most animals, PGCs migrate from sites of formation to the somatic gonad. Here, we investigated whether they also exhibit similar migratory behaviors using live-cell imaging of small micromere plasma membranes. Results: Early in gastrulation, small micromeres transition from non-motile epithelial cells, to motile quasi-mesenchymal cells. Late in gastrulation, at 43 hr post fertilization (HPF), they are embedded in the tip of the archenteron, but remain motile. From 43-49 HPF, they project numerous cortical blebs into the blastocoel, and filopodia that contact ectoderm. By 54 HPF, they begin moving in the plane of the blastoderm, often in a directed fashion, towards the coelomic pouches. Isolated small micromeres also produced blebs and filopodia. Conclusions: Previous work suggested that passive translocation governs some of the movement of small micromeres during gastrulation. Here we show that small micromeres are motile cells that can traverse the archenteron, change position along the left-right axis, and migrate to coelomic pouches. These motility mechanisms are likely to play an important role in their left-right segregation. (C) 2014 Wiley Periodicals, Inc.

Bosnjak, I, Uhlinger KR, Heim W, Smital T, Franekic-Colic J, Coale K, Epel D, Hamdoun A.  2009.  Multidrug Efflux Transporters Limit Accumulation of Inorganic, but Not Organic, Mercury in Sea Urchin Embryos. Environmental Science & Technology. 43:8374-8380.   10.1021/es901677r   AbstractWebsite

Mercuric compounds are persistent global pollutants that accumulate in marine organisms and in humans who consume them. While the chemical cycles and speciation of mercury in the oceans are relatively well described, the cellular mechanisms that govern which forms of mercury accumulate in cells and why they persist are less understood. In this study we examined the role of multidrug efflux transport in the differential accumulation of inorganic (HgCl(2)) and organic (CH(3)HgCl) mercury in sea urchin (Strongylocentrotus purpuratus) embryos. We found that inhibition of MRP/ABCC-type transporters increases intracellular accumulation of inorganic mercury but had no effect on accumulation of organic mercury. Similarly, pharmacological inhibition of metal conjugating enzymes by ligands GST/GSH significantly increases this antimitotic potency of inorganic mercury, but had no effect on the potency of organic mercury. Our results point to MRP-mediated elimination of inorganic mercury conjugates as a cellular basis for differences in the accumulation and potency of the two major forms of mercury found in marine environments.