Structural studies of molecules involved in the bacterial defense in Atlantic salmon

---

Project leader: Professor Trond Ø. Jørgensen

Toll-like receptors (TLR) recognize conserved pathogen-associated molecular patterns (PAMPs) and are involved in the immune system of both invertebrates and vertebrates. In mammals there are at least 10 different TLR which recognizes different classes of microbial molecules. Examples of TLR ligands are LPS, glucan, dobbelstranded RNA and unmethylated Cpg oligonucleotides. The NF- kB activation pathway and type I IFN-producing pathway are usually activated in response to these PAMPs. All of the TLRs studied so far share the same overall structure. They consists of an extracellular Leucine rich domain (LRR), a transmembrane helix (TM), and a intercellular signaling domain called TIR. Although TLRs have been extensively studied in mammals, only a few studies of these genes have been conducted in fish.
We have cloned and sequenced several TLRs from Atlantic salmon and cod and studied their expression patterns in different fish tissues. They show in general low expression but can be found in most tissues. Further we aim to study the functional properties of these TLRs in fish and compare them to their mammalian counterparts.