New insights on macrophage migration inhibitory factor: based on molecular and functional analysis of its homologue of Chinese amphioxus.

Macrophage migration inhibitory factor (MIF) is an intricate cytokine. Many questions about it are not fully resolved. In order to identify the role of MIF in Chinese amphioxus, its genomic organization, transcription pattern and enzymatic activity were studied. It's found that MIF has multi-copy gene number in the Chinese amphioxus genome and special transcription pattern in reproductive organs. Interestingly, the recombinant Bbt-MIF has tantomerase and redox activity, but fails to utilize GSH to reduce insulin instead of DTT, strikingly different from MIF in mammalian. All these results indicate that MIF gene must have undergone important changes in structure and function during the transition of invertebrate/vertebrate and might exert important role in this primitive species, which may be quite different from those found in vertebrate.