Expression pattern of arenicins—the antimicrobial peptides of polychaete Arenicola marina

Abstract

Immune responses of invertebrate animals are mediated through innate mechanisms, among which production of antimicrobial peptides play an important role. Although evolutionary Polychaetes represent an interesting group closely related to a putative common ancestor of other coelomates, their immune mechanisms still remain scarcely investigated. Previously our group has identified arenicins—new antimicrobial peptides of the lugworm Arenicola marina, since then these peptides were thoroughly characterized in terms of their structure and inhibitory potential. In the present study we addressed the question of the physiological functions of arenicins in the lugworm body. Using molecular and immunocytochemical methods we demonstrated that arencins are expressed in the wide range of the lugworm tissues—coelomocytes, body wall, extravasal tissue and the gut. The expression of arenicins is constitutive and does not depend on stimulation of various infectious stimuli. Most intensively arenicins are produced by mature coelomocytes where they function as killing agents inside the phagolysosome. In the gut and the body wall epithelia arenicins are released from producing cells via secretion as they are found both inside the epithelial cells and in the contents of the cuticle. Collectively our study showed that arenicins are found in different body compartments responsible for providing a first line of defense against infections, which implies their important role as key components of both epithelial and systemic branches of host defense.

Novel Antimicrobial Peptides from the Arctic Polychaeta Nicomache minor Provide New Molecular Insight into Biological Role of the BRICHOS Domain

“…Polychaeta species are strictly dependent on epithelial barrier continuity and efficacy of the innate immune system, which are vitally important for their protection against pathogenic microorganisms. The BRICHOS-related peptides, arenicins and alvinellacin, are constitutively expressed both in coelomocytes and in the tegument of hosts, thus indicating involvement of the peptides in both systemic and local epithelial immunity [ 8 , 50 ]. Localization of the nicomicins needs further elucidation with the use of immunohistochemistry approaches.…”

Marine antimicrobial peptide arenicin adopts a monomeric twisted β‐hairpin structure and forms low conductivity pores in zwitterionic lipid bilayers

“…Second, the mature arenicins are stored within cytosolic granules of celomocytes, which undergo fusion with phagosome. Arenicins functioning this way participate in inactivation of the phagocytized pathogens, instead of being secreted into celomic cavity . Molecular insight into mechanisms responsible for the arenicin cytotoxicity is needed for design of new antibacterial compounds.…”

Potential chemical defenses of Antarctic benthic organisms against marine bacteria

“…Among all phyla tested in this study, Annelida presented the highest percentage of bacterial inhibition effect but with only four representatives, three of which were active. The production of natural compounds with antimicrobial properties by annelids is well known at different geographic latitudes but not in the Antarctic region (Chain & Anderson 1983;Elayaraja et al 2010;Maltseva et al 2014). Bryozoa, Echinodermata, Hemichordata and Chordata were better sampled, with a percentage of active organisms 1.7 (1-2) ++ a int, internal; ext, external; api, apical; bas, basal.…”