A weird MIF coming out the blue

Abstract

The cytokines MIF (Macrophage migration inhibitory factor) have been discovered for the first time 50 years ago. MIF is a pleiotropic protein involved cell cycle regulation, modulation of immunity response, inhibition of apoptosis, as well as in infectious and immune diseases including septic shock, colitis, malaria, rheumatoid arthritis, and atherosclerosis, and tumorigenesis. Recent studies showed that these proteins play a major role in invertebrate immunity and are secreted by parasites to inhibit host defense responses, raising the question of MIF diversity, their evolutionary history and functional differences.

So far, MIFs are described as small single domain proteins from 12 to 15kDa conserved across kingdoms (plants, fungi, protists, metazoan…). Unexpectedly, we identified a longer MIF protein harboring a transmembrane domain in autotrophic marine protists raising exciting functional questions. The aim of this explorative study was to validate the existence of such transmembrane MIF, explore their transmembrane location and potential function(s).