Identifying Components of the NF-κB Pathway in the Beneficial Euprymna scolopes - Vibrio fischeri Light Organ Symbiosis

Abstract

The Toll/NF-B pathway is a common, evolutionarily conserved innate immune pathway that modulates the responses of animal cells to microbe-associated molecular patterns (MAMPs). Because MAMPs have been implicated as critical elements in the signaling of symbiont-induced development, an expressed sequence tag library from the juvenile light organ of Euprymna scolopes was used to identify members of the Toll/NF-B pathway. Full-length transcripts were identified by using 5 and 3 RACE PCR. Seven transcripts critical for MAMP-induced triggering of the Toll/NF-B phosphorylation cascade have been identified, including receptors, signal transducers, and a transcription factor. Further investigations should elucidate the role of the Toll/NF-B pathway in the initiation of the beneficial symbiosis between E. scolopes and Vibrio fischeri.

Characteristic and functional analysis of Toll-like receptors (TLRs) in the lophotrocozoan, Crassostrea gigas, reveals ancient origin of TLR-mediated innate immunity

“…Such structural organization is also found in other mollusk TLR families; most members possess sccTLRtype structures but minorities are mccTLRs, e.g. only three out of 23 TLRs from Mytilus galloprovincialis, one out of 7 TLRs from Euprymna scolopes and four out of 70 TLRs from Pinctada fucata are mccTLRs [17,27]. All of these findings challenge previous assumptions that the distribution of sccTLR and mccTLR have corresponding relationships with deuterostomes and protostomes; most sccTLRs are found in deuterostomes, while most mccTLRs are found in protostomes such as insects, nematodes and mollusca [15][16][17]27].…”

“…only three out of 23 TLRs from Mytilus galloprovincialis, one out of 7 TLRs from Euprymna scolopes and four out of 70 TLRs from Pinctada fucata are mccTLRs [17,27]. All of these findings challenge previous assumptions that the distribution of sccTLR and mccTLR have corresponding relationships with deuterostomes and protostomes; most sccTLRs are found in deuterostomes, while most mccTLRs are found in protostomes such as insects, nematodes and mollusca [15][16][17]27]. Moreover, recent genomic analysis showed the co-existence of two TLR types in the ancient invertebrate deuterostome, S. purpuratus and B. lanceolatum [28], which strongly implies that both sccTLR and mccTLR have already presented in the bilateria ancestor, but have independently evolved and preferentially expanded, either respectively, or in individual species after deuterostome-protostome divergence.…”

Toll-like receptors — taking an evolutionary approach

“…They represent the sister group of ecdysozoans (that is, arthropods and nematodes) and, therefore, studies on TLRs in this group might shed light on the ancestral function of TLRs in the bilaterian ancestor. Multiple cysteine cluster TLRs (mccTLRs) have been identified in cephalopod molluscs, including the Hawaiian squid (Euprymna scolopes) 125 and in a divergent marine bivalve, the Zhikong scallop (Chlamys farreri) 126 . TLRs are also present in the annelid phylum as several mccTLRs have been identified in genomic traces of the polychaete annelid Capitella sp.…”

“…Given the molecular divergence of lophotrocozoan TLRs, it is evident that they have evolved independently from arthropod and nematode TLRs 125 . However, contrary to nematodes, nuclear factor-kappa B (NF-κB) factors have been identified in molluscs 125 and annelids 127,128 (G. Balavoine, personal communication), suggesting that lophotrochozoan TLRs might have retained the ability to control NF-κB signalling (FIG. 2).…”

Functional characterization of a short peptidoglycan recognition protein, PGRP5 in grass carp Ctenopharyngodon idella

“…The first PGRP was discovered in 1996 in silkworm (Bombyx mori) as a 19-kDa protein, which bound to PGN and activated prophenoloxidase cascade, an antimicrobial host defense mechanism in insects [1]. Subsequently, PGRPs have been identified in insects such as Drosophila melanogaster [2] and Anopheles gambiae [3], and in other invertebrates such as molluscs and echinoderms [4,5], as well as in vertebrates, including fish, amphibians, birds and mammals [6e9].…”