OBJECTIVETo clone and express a homologue of human macrophage migration inhibitory factor (MIF) from P. falciparum 3D7--PfMIF.

METHODSThe nucleotide sequence of PfMIF was found through blast P. falciparum genomic sequence databases with the amino acid sequence of human MIF (HuMIF). RT-PCR, DNA sequencing, and bioinformatics analysis were used for the cloning of Pfmif gene. The recombinant protein was expressed in E. coli and purified through the affinity column.

RESULTSThe full length of Pfmif gene was cloned and sequenced. It was composed of 351 nucleotides and encoded 116 amino acids with the typical characteristic of MIF family. The recombinant protein was successfully expressed and purified.

CONCLUSIONSThe Pfmif gene and recombinant protein were successfully isolated and PfMIF was preliminarily identified as a novel member of MIF family.

Amino Acid Sequence ; Animals ; Base Sequence ; Cloning, Molecular ; Escherichia coli ; genetics ; Humans ; Macrophage Migration-Inhibitory Factors ; biosynthesis ; genetics ; isolation & purification ; Molecular Sequence Data ; Plasmodium falciparum ; genetics ; metabolism ; Protozoan Proteins ; biosynthesis ; genetics ; isolation & purification ; Recombinant Proteins ; biosynthesis ; genetics ; Sequence Homology, Amino Acid

OBJECTIVETo investigate the interaction domains between macrophage migration inhibitory factors (MIF) and the extracellular segment of type-II trans-membrane protein CD74 using a yeast two-hybrid system.

METHODSBy using molecular cloning techniques, the DNA fragments encoding MIF, MIF(50-65) and MIF(1-50/65-115) were introduced into the pGBKT7 vector to construct the corresponding recombinant bait plasmids, and the DNA fragments encoding CD74(73-232), CD74(73-109), CD74(1109-149) and CD74(149-232) into the pGADT7 vector to construct the recombinant activation domain (AD) plasmids. PEG/LiAC method was employed to transform the above 3 recombinant bait plasmids paired with each of the 4 recombinant AD plasmids into the chemical competent yeast AH109 cells. The transformed yeast AH109 cells were screened consecutively on SD/-Trp-Leu and SD/-Trp-Leu-Ade-His/X-alpha-gal nutritional media.

RESULTSThe results of restriction endonuclease digestion and DNA sequencing verified the correct construction of all the recombinant plasmids. The yeast AH109 cells transformed with each of the 3 recombinant bait plasmids could grow on SD/-trp nutritional media without autonomous activation effect on the reporter gene MEL1. The cells transformed with each of the 4 recombinant AD plasmids could also grow on SD/-leu nutritional media without activation of the reporter gene MEL1. Only the yeast AH109 cells co-transformed with MIF, MIF(50-65), or MIF(1-50/65-115) plasmid and CD74(73-232) plasmid could grow on SD/-Trp-Leu-Ade-His nutritional media with transcription activation of the reporter gene MEL1.

CONCLUSIONMIF interacts with the intact extracellular segment of CD74 (CD74(73-232)) independent of the functional domain of MIF(50-65).

Antigens, Differentiation, B-Lymphocyte ; genetics ; metabolism ; Cloning, Molecular ; Escherichia coli ; genetics ; metabolism ; Extracellular Matrix ; metabolism ; Histocompatibility Antigens Class II ; genetics ; metabolism ; Macrophage Migration-Inhibitory Factors ; genetics ; metabolism ; Peptide Fragments ; genetics ; Protein Interaction Domains and Motifs ; genetics ; Recombinant Proteins ; biosynthesis ; genetics ; Two-Hybrid System Techniques

BACKGROUND/AIMS: This study was undertaken to identify the intracellular signaling pathway involved in induction of macrophage migration inhibitory factor (MIF) in human rheumatoid arthritis (RA) synovial fibroblasts. METHODS: Human RA synovial fibroblasts were treated with concanavalin A (ConA), various cytokines, and inhibitors of signal transduction molecules. The production of MIF by synovial fibroblasts was measured in culture supernatants by ELISA. The expression of MIF mRNA was determined using reverse transcriptase polymerase chain reaction (RT-PCR) and real-time PCR. Phosphorylation of p38 mitogen-activated protein (MAP) kinase in synovial fibroblasts was confirmed using Western blotting. The expression of MIF and p38 MAP kinase in RA synovium was determined using dual immunohistochemistry. RESULTS: The production of MIF by RA synovial fibroblasts increased in a dose-dependent manner after ConA stimulation. MIF was also induced by interferon-gamma, CD40 ligand, interleukin-15, interleukin-1beta, tumor necrosis factor-alpha, and transforming growth factor-beta. The production of MIF by RA synovial fibroblasts was significantly reduced after inhibition of p38 MAP kinase. The expression of MIF and p38 MAP kinase was upregulated in the RA synovium compared with the osteoarthritis synovium. CONCLUSIONS: These results suggest that MIF production was induced through a p38 MAP-kinase-dependent pathway in RA synovial fibroblasts.
Arthritis, Rheumatoid/genetics/*metabolism ; Base Sequence ; Cells, Cultured ; Concanavalin A/pharmacology ; Cytokines/pharmacology ; DNA Primers/genetics ; Fibroblasts/drug effects/metabolism ; Humans ; Macrophage Migration-Inhibitory Factors/*biosynthesis/genetics ; RNA, Messenger/genetics/metabolism ; Signal Transduction/drug effects ; Synovial Membrane/drug effects/metabolism ; p38 Mitogen-Activated Protein Kinases/metabolism