[Teleost Type 2 Interleukin-1 Receptor (IL-1R2) from the Spotted Halibut (Verasper variegatus): 3D Structure and a Role in Immune Response].

The type 2 interleukin-1 receptor (IL-1R2) is one of natural IL-1ß singling inhibitors in mammals. We cloned and sequenced the IL-1R2 gene in V. variegatus (VvIL-1R2). The phylogenetic analysis showed that the molecular structure VvIL-1R2 is similar to that of its orthologues in other vertebrates. The expression levels of VvIL-1R2 are relatively high in the peripheral blood leukocytes (PBLs), gill, and spleen. In addition, peculiar expression patterns for his molecule were detected at various developmental stages, implying that in flatfishes the IL-1R2 may have be important for embryonic development and metamorphosis. In PBLs, the treatment with pathogen-associated molecular patterns (PAMPs) induced a significant and rapid up-regulation of VvIL-1R2, pointing at its involvement in the immune responses against bacterial and viral pathogens.

Development of 'Redox Arrays' for identifying novel glutathionylated proteins in the secretome.

Proteomics techniques for analysing the redox status of individual proteins in complex mixtures tend to identify the same proteins due to their high abundance. We describe here an array-based technique to identify proteins undergoing glutathionylation and apply it to the secretome and the proteome of human monocytic cells. The method is based on incorporation of biotinylated glutathione (GSH) into proteins, which can then be identified following binding to a 1000-protein antibody array. We thus identify 38 secreted and 55 intracellular glutathionylated proteins, most of which are novel candidates for glutathionylation. Two of the proteins identified in these experiments, IL-1 sRII and Lyn, were then confirmed to be susceptible to glutathionylation. Comparison of the redox array with conventional proteomic methods confirmed that the redox array is much more sensitive, and can be performed using more than 100-fold less protein than is required for methods based on mass spectrometry. The identification of novel targets of glutathionylation, particularly in the secretome where the protein concentration is much lower, shows that redox arrays can overcome some of the limitations of established redox proteomics techniques.

Stabilization by urea during thermal unfolding-mediated aggregation of recombinant human interleukin-1 receptor (type II): does solvation entropy play a role?

The protein denaturing properties of urea are well-known and still the subject of debate. It has been noted that in some cases where urea concentrations are relatively low stabilization is afforded against aggregation. An explanation for this unusual effect has seemingly remained elusive. Evidence is offered to propose urea stabilization is related to its influence on the solvation property of the protein molecules when in contact with an unfolded hydrophobic surface that tends to increase the entropy of the local aqueous solvent. This property of urea is expected to lower the entropic driving force of unfolded-mediated aggregation despite the increase in enthalpy. The data presented from toluene transfer experiments into 2 M urea + 0.1 M sodium phosphate solutions showed that the solvation free energy change was negative up to ∼75 °C. The associated ΔΔH was positive, leading to the conclusion that entropy drives the solvation process within the temperature domain from ∼20° to 75 °C. Using thermodynamic parameters from the toluene solvation experiments, it was possible to accurately determine the T(m) shift of recombinant human interleukin-1 receptor type II (rhuIL-1R(II)). Heating experiments above the apparent T(m) in the same urea/phosphate solution support the thesis that urea inhibits the entropy-driven aggregation process of rhuIL-1R(II), adding yet another molecule to the list of low urea concentration stabilized molecules.

Structural insights into the assembly and activation of IL-1ß with its receptors.

Interleukin 1ß (IL-1ß) is a key orchestrator of inflammation and host defense that exerts its effects through IL-1 receptor type I (IL-1RI) and IL-1 receptor accessory protein (IL-1RAcP). How IL-1RAcP is recruited by IL-1ß-IL-1RI to form the signaling-competent complex remains elusive. Here we present the crystal structure of IL-1ß bound to IL-1 receptor type II (IL-1RII) and IL-1RAcP. IL-1ß-IL-1RII generated a composite binding surface to recruit IL-1RAcP. Biochemical analysis demonstrated that IL-1ß-IL-1RI and IL-1ß-IL-1RII interacted similarly with IL-1RAcP. It also showed the importance of two loops of IL-1 receptor antagonist (IL-1Ra) in determining its antagonism. Our results provide a structural basis for assembly and activation of the IL-1 receptor and offer a general cytokine-receptor architecture that governs the IL-1 family of cytokines.

Cloning and characterization of type II interleukin-1 receptor cDNA from Japanese flounder (Paralichthys olivaceus).

The type II interleukin-1 receptor (IL-1RII) cDNA was cloned from Japanese flounder (Paralichthys olivaceus) by mRNA differential display (DD-PCR) and rapid amplification of cDNA ends (RACE). The full-length cDNA is 1793 bp in length, including a 100 bp 5'-terminal untranslated region (UTR), a 430 bp 3'-terminal UTR, and a 1263 bp open reading frame (ORF). The ORF encodes 420 amino acid residues with an estimated molecular mass of 46.65 kDa. The protein possesses signature features of the IL-R family, consisting of one N-terminal signal peptide, one transmembrane (TM) domain, two Ig-like domains in its extracellular region, one short cytoplasmic tail of 17 amino acids and four conserved proline residue sites. The predicted amino acid sequence has 65.3%, 52.5% and 51.6% identity with gilthead seabream, rainbow trout and Atlantic salmon IL-1RII, respectively. Phylogenetic analysis supported a close relation to mammalian IL-1RII. Reverse Transcription Polymerase Chain Reaction (RT-PCR) analysis indicated that the IL-1RII gene expression of Japanese flounder was weakly up-regulated and reached the peak expression in the kidney, spleen, and gill at 6 h after infection with Vibrio anguillarum, at 1.9, 2.0 and 1.5 times relative to the uninfected fish, respectively. These results suggest that IL-1RII has a signal transduction function and possibly plays a minor role in immune regulation against bacterial(s) infection in Japanese flounder.