The defensive skin secretions of many amphibians constitute of rich mixtures of peptide toxins that are thought to play a role in deterring predators. In order for these molecules to arrive at their target sites (in most cases hormone receptors), skin secreted compounds rely on epithelial absorption for toxin administration. However, exactly how defensive peptides manage to overcome epithelial barriers in order to be adaptive for an amphibian being preyed upon, remains an understudied aspect of their functional biology. Here we show that in vitro transepithelial passage of the hormone-like toxin caerulein is mediated by the co-secreted AMP (antimicrobial peptide) CPF-Xl5. We found that treatment of model epithelia with CPF-Xl5 resulted in steep drops in epithelial electrical resistance (a measure for epithelial integrity). Membrane damage assays showed that CPF-Xl5 causes cell membrane permeation within one minute, indicating that the membrane damaging capacity of CPF-Xl5 underlied the observed drops in epithelial resistance. Furthermore, we found that passage of caerulein across model epithelia was strongly enhanced in the presence of CPF-Xl5, suggesting a pivotal role of CPF-Xl5 in transepithelial transport. Our results demonstrate an AMP-mediated transport mechanism of peptides across epithelial barriers. Moreover, our results lend in vitro support to the hypotheses that amphibian AMPs accelerate the epithelial absorption of co-secreted toxins, serving in antipredator defence. Our findings may change prevailing concepts regarding amphibian poisons, and suggest that we might have to change our view on the adaptive function of skin-secreted peptides.
Date of Award | 25 Jun 2014 |
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Original language | English |
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Supervisor | Kim Roelants (Promotor) & Frank Pasmans (Co-promotor) |
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- amphibians
- antipredator defense
- antimicrobial peptide
Elucidating the Adaptive Role of Amphibian Antimicrobial Peptides in Antipredator Defence: An in vitro study.
Raaymakers, C. ((PhD) Student), Roelants, K. (Promotor), Pasmans, F. (Co-promotor). 25 Jun 2014
Student thesis: Master's Thesis