Journal of Drug Metabolism & Toxicology
Open Access

Unraveling the mechanisms of hBD3 internalization and trafficking in the A549 epithelial airway type of cells: A key role for the complex CD98 membrane protein

2^nd World Congress and Exhibition on Antibiotics and Antibiotic Resistance

October 13-15, 2016 Manchester, UK

Ersilia Nigro

CEINGE-Biotecnologie Avanzate, Italy

Posters & Accepted Abstracts: J Drug Metab Toxicol

Abstract :

Human beta defensins (hBDs) are small cationic peptides that play a pivotal role in the innate immune response. They exert direct antimicrobial activity against a wide spectrum of bacteria and viruses; their expression is up-regulated during infection and inflammation. All hBDs are secreted by epithelia, which represent their natural site of action. However, little is known about their interaction with human epithelial cells. Here, we used a functional proteomic approach to search for cell surface receptors that could play a role in the interaction and internalization of hBD3 in A549 cells. Out of the proteins identified through this analysis we focused on CD98, a type II transmembrane protein involved in amino acid transport, cell adhesion, inflammation, immune response and attachment of enteric bacterial pathogens. Through confocal microscopy we found that CD98 and hBD3 extensively colocalize on the basolateral domain of A549 cells. We then confirmed their direct binding by fluorescence resonance energy transfer and surface Plasmon resonance and mapped the region of interaction to residues 304-414 of CD98. Finally, we found that knockdown of CD98 expression in A549 cells impairs both hBD3 cell surface binding and internalization and conversely treatment of A549 cells with hBD3 dramatically reduces the expression of CD98. Overall, these data provide evidence that CD98 plays a specific role in hBD3 membrane trafficking, assisting the ready entry and internalization of the peptide in epithelial cells. The interaction of hBD3 with CD98 and in particular the down-regulation of its expression might have a functional role in the activity of hBD3.

Biography :

Email: nigro@ceinge.unina.it