MIF from mussel: Coding sequence, phylogeny, polymorphism, 3D model and regulation of expression

Abstract

a b s t r a c tThree macrophage migration inhibitory factor (MIF)-related sequences were identified from a Mytilus galloprovincialis EST library. The consensus sequence included a 5 0 -UTR of 32 nucleotides, the complete ORF of 345 nucleotides, and a 3 0 -UTR of 349 nucleotides. As for other MIFs, M. galloprovincialis ORF does not include any signal or C-terminus extensions. The translated sequence of 115 amino acids possesses a molecular mass of 12,681.4, a pI of 6.27 and a stability index of 21.48. Its 3D structure resembles human MIF except for one shorter a-helix. Although evolutionary separated from ticks and vertebrates, Mg-MIF appeared to be closely related to Pinctada fucata and Haliotis, but not to Chlamys farreri and Biomphalaria glabrata. Numerous mutation points were observed within the Mg-MIF ORF, defining 11 amino acid variants within the mussels from Palavas-France and 14 amino acid variants within the mussels from Palermo-Italy. The 2 major variants from Palavas were identical to 2 of the 4 major variants from Palermo. In all the 18 Mg-MIF variants, residues involved in tautomerase and in oxidoreductase activities were conserved. Generally, one mussel expressed 2 Mg-MIF amino acid sequences but with different frequencies of occurrence. Mg-MIF is constitutively expressed principally in hemocytes and in the mantle. In contrast to other animal models, Mg-MIF expression was always down regulated following challenge by bacteria and fungi, confirming previous data obtained with microarray. Down regulation started as soon as 1 h and Mg-MIF expression returned to background 9-48 h after the challenge. Exception was regarding the yeast, Candida albicans, down-regulation between 9 and 72 h, suggesting yeast and bacteria-filamentous fungi trigger different mechanisms of elimination.

An updated molecular basis for mussel immunity

“…Two other inflammatory cytokines have been identified by similarity searches in bivalves: the macrophage migration inhibitory factor (MIF), which is present with at least three distinct gene products in M. galloprovincialis [213], and the allograft 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 inflammatory factor (AIF), able to stimulate the phagocytic activity of granulocytes, which has been identified in different bivalve species [214e216] and is now confirmed also in M. galloprovincialis.…”

Proteomic characterization of mucosal secretions in the eastern oyster, Crassostrea virginica

“…In this study, a macrophage migration inhibitory factor (ADU19847) was identified and suggested to be a proinflammatory cytokine with the ability to induce various immunomodulatory and proinflammatory responses in vertebrates and invertebrates [143][144][145]. Transcripts of MIF have been shown to be expressed and regulated in response to microbial stimuli in different organs including pallial or digestive tissues in mussels [146] and oysters [147].…”

Responses of marine mussel Mytilus galloprovincialis (Bivalvia: Mytilidae) after infection with the pathogen Vibrio splendidus

“…Previous researches have demonstrated a great diversity in the immune responses of mussels, both at inter and intra-population level, in relation to the microorganism to which they are exposed . In mussel M. galloprovincialis, widely used as an experimental model species of bacterial infection, it has been demonstrated a recruitment of hemocytes containing antimicrobial peptides (AMPs), including mytilins, towards the site of injection within hours following bacterial challenge, along with a prominent role of mytilins in killing intracellular bacteria after phagocytosis (Mitta et al, 2000a;Parisi et al, 2012;Sonthi et al, 2012). Furthermore, an increase of soluble AMPs in the plasma of mussels suggests the occurrence of secondary systemic responses to microbial challenges (Mitta et al, 2000b;Toubiana et al, 2014).…”