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MIF-induced augmentation of melatonin functions: possible relevance to mechanisms of action of MIF-1 in movement disorders.

MIF-1, a synthetic tripeptide with MSH-release inhibitory properties, has been reported to improve symptoms of Parkinson's disease, attenuate levodopa-related dyskinesias and diminish the dyskinetic movements of Tardive dyskinesia. More recently, MIF-1 has been reported partially to protect against the nigro-striatal dopamine depleting effects of MPTP in mice, raising the possibility that it may exert protective effects against the development of Parkinson's disease. There is evidence to suggest that MIF-1 increases nigro-striatal dopaminergic activity, but its ability to improve symptoms in patients with Parkinson's disease, levodopa-related dyskinesias and Tardive dyskinesia cannot be explained solely on the basis of the drug's effect on striatal dopaminergic neurons. MIF-1 has been reported to potentiate the melanocyte-lightening effect of melatonin in rats and its effects in patients with Parkinson's disease and Tardive dyskinesia are associated with marked mood elevation. It is, therefore, possible that the effects of MIF-1 in movement disorders are associated with increased melatonin secretion. Thus, hypothalamic MIF may modulate nigro-striatal dopaminergic functions in part via pineal melatonin. Such an interaction represents a novel mechanism by which hypothalamic peptides act to modulate the expression of movement disorders.

Affect↗

Effects of Tyr-MIF-1 and MIF-1 at the GABAA receptor chloride channel site.

The peptides Tyr-MIF-1 (Tyr-Pro-Leu-Gly-NH2) and, to a lesser extent, MIF-1 (Pro-Leu-Gly-NH2) recently have been found to augment the effects of gamma-aminobutyric acid (GABA) on benzodiazepine receptor binding at the GABAA receptor complex. To assess their interaction with the chloride channel binding site on the GABAA receptor, we evaluated the effects of these two peptides on [35S]-t-butylbicyclophosphorothionate (TBPS) binding in mouse brain membranes. In cortex, neither peptide altered [35S]-TBPS binding over a broad dose range, but Tyr-MIF-1 significantly augmented displacement of radioligand binding by the GABA analog muscimol at peptide concentrations of 10(-10) to 10(-7) M; MIF-1 had little effect on muscimol displacement of [35S]-TBPS binding. In cerebellum and brainstem, neither peptide was active in altering muscimol displacement of binding. Thus, Tyr-MIF-1 augments the displacement of [35S]-TBPS binding by the GABA analog muscimol in mouse brain cortical membranes, indicating that this peptide enhances the effects of GABA at the chloride channel as well as at the benzodiazepine receptor.

Animals↗

Regional differences in the metabolism of Tyr-MIF-1 and Tyr-W-MIF-1 by rat brain mitochondria.

Tyr-MIF-1 (Tyr-Pro-Leu-Gly-NH2) and Tyr-W-MIF-1 (Tyr-Pro-Trp-Gly-NH2) are endogenous neuropeptides with opiate modulating and other CNS effects. After incubation of the tritiated tetrapeptides with fractions of tissue from different areas of rat brain, formation of the metabolites was determined by HPLC. Marked regional differences in degradation were found for both peptides. The metabolism of Tyr-MIF-1, resulting in the formation of the biologically active MIF-1 (Pro-Leu-Gly-NH2), was greater in the mitochondrial than in the synaptosomal fractions. In the mitochondrial fraction, about twice as much MIF-1 was formed in brain cortex than in striatum, diencephalon, or midbrain/pons medulla. These results, showing differential metabolism in various areas of the brain, indicate another means for regulation of the concentrations of neuropeptides.

Animals↗

Macrophage-lymphocyte interaction in migration inhibition factor (MIF) production against soluble or cellular tumor-associated antigens. I. Characteristics and genetic control of two different mechanisms of stimulating MIF production.

For MIF production in response to 3 M KCl extracts of tumor, viable and metabolically active macrophages have been shown to be required to interact with the soluble tumor antigens and then come in contact with immune lymphocytes. The Mphi-lymphocyte interaction for MIF production was found to be under the control of genes mapping in the IA subregion of the H-2 complex. However, when intact tumor cells were used as antigen, Mphi were not required for immune lymphocytes to produce MIF. In addition, the interaction of immune lymphocytes with tumor cells for MIF production did not require H-2 compatibility. These and other observations strongly suggest that there are two different mechanisms for MIF production and that these may be mediated by two separate subpopulations of immune lymphocytes.

Animals↗

A monoclonal antibody against migration inhibitory factor (MIF) obtained by immunization with MIF from the human lymphoblast cell line Mo.

A monoclonal antibody-secreting hybrid cell line, E7, was constructed from myeloma cells and spleen cells from BALB/c mice immunized with partially purified human MIF from culture fluid of the human T-lymphoblast cell line Mo. The hybrid cell line E7 was selected by screening hybridoma cultures for their capacity to adsorb added MIF activity when assayed together with rabbit anti-mouse IgG-coupled to protein A-Sepharose. The monoclonal antibody produced by the cloned hybridoma E7 also directly neutralized MIF activity from Mo cells and two species of MIF from the culture fluid of human peripheral blood lymphocytes, but did not neutralize IFN-gamma from Mo cells and from human peripheral blood lymphocytes. This antibody reacted also with a component in phytohemagglutinin preparations with an apparent molecular weight of 60,000; however, it did not react with the active tetramer of phytohemagglutinin.

Animals↗

Differential inhibitory effects of MIF-1, Tyr-MIF-1, naloxone and beta-funaltrexamine on body rotation-induced analgesia in the meadow vole, Microtus pennsylvanicus.

The effects of body rotation in a horizontal plane and various opiate antagonists on the nociceptive responses of a day-active microtine rodent, the meadow vole, Microtus pennsylvanicus, were examined. Intermittent rotation (70 rpm, schedule of 30 sec on, 30 sec off) for 30 min induced significant analgesic responses in the voles for 15 min after rotation. These increases in thermal response latency were blocked by intraperitoneal pretreatment with either naloxone or the irreversible mu opiate receptor antagonist beta-funaltrexamine (beta-FNA; 10 mg/kg; 24 hr pretreatment). This antagonistic effect of beta-FNA indicates mu opioid involvement in the mediation of rotation-induced analgesia. The antiopiate peptides MIF-1 (Pro-Leu-Gly-NH2) and Tyr-MIF-1 also significantly reduced, though did not completely block, body rotation-induced opiate analgesia. This suggests that Tyr-MIF-1 and MIF-1 have significant antagonistic effects on mu opioid systems that are involved in the mediation of stress (rotation)-induced analgesia.

Analgesia↗

Human B cells secrete migration inhibition factor (MIF) and present a naturally processed MIF peptide on HLA-DRB1*0405 by a FXXL motif.

A better knowledge of peptide structures interacting with major histocompatibility complex (MHC) molecules is of great interest for better understanding of the molecular basis of immune recognition. We have isolated naturally processed peptides from a continuously growing antigen-presenting Epstein-Barr virus-transformed human B-cell line. HLA-DR complexes were purified by specific affinity chromatography and complexed peptides were released by acid treatment. The isolated peptides were separated by reversed phase chromatography and fractions were analysed by Edman degradation at picomolar ranges. From 30 fractions that were examined seven peptides bound to the HLA-DRB1*0405 and two peptides from the human leucocyte antigen (HLA) class II associated invariant chain bound to HLA-DRB1*1302. In addition, a N-terminal beta-chain peptide of the 0405 allele was identified. Evaluation of amino acid sequences revealed a refined FXXL motif for the 0405 allele, in which F (phenylalanine) stands for any aromatic amino acid and L (leucine) can be exchanged by either I (isoleucine) or V (valine). In total, three fractions contained a peptide derived from the human migration inhibition factor (MIF), a pro-inflammatory cytokine that is normally produced by activated T lymphocytes and monocytes/macrophages. Indeed, cytokine analysis revealed high amounts of MIF secreted by the B-cell line, confirming that MHC class II expressing cells can present any intrinsic peptide that contains the distinct motif for HLA-binding. For MIF, the amino acid sequence Y36IAV39 represents the required binding motif for HLA-DRB1*0405. Nevertheless, it is the first time that cytokine fragments were found to bind to HLA molecules on human B cells.

Alleles↗

Macrophage migration inhibitory factor (mif) transcription is significantly elevated in Caenorhabditis elegans dauer larvae.

Macrophage migration inhibitory factor (MIF) from vertebrate species is a molecule that exerts a wide-range of effects in inflammatory responses, cell activation and cell differentiation. Several species of parasitic nematodes have been shown to express genes encoding orthologues of the mammalian MIF that appear to play a key role in immune evasion by modifying the activity of host cells. In addition, MIF accumulates in nematode somatic cells where its role has not yet been defined. In order to identify the role that MIF plays in the cell biology of nematodes, we have characterized the members of the mif gene family in the free-living species Caenorhabditis elegans. Unlike the single mif gene found in humans and mice, C. elegans expresses four distinct mif genes: Ce-mif-1, Ce-mif-2, Ce-mif-3 and Ce-mif-4. The Ce-MIF proteins are between 15-30% identical to each other, 34-38% identical to the MIFs from the parasitic nematode Brugia malayi, and 22-35% identical to mammalian MIFs. The transcription of Ce-mif-2 and Ce-mif-3, but not Ce-mif-1, was upregulated >100-fold compared to L2 levels when the worms entered the dauer stage. The transcription levels of Ce-mif-2 and Ce-mif-3 fell to near baseline a few hours after exit from dauer. Ce-MIF/GFP transgenic animals and immunostaining were used to demonstrate that the main sites of MIF production are in the hypodermis, body wall muscles and in the nuclei of developing embryos. The results suggest a role for C. elegans MIF in cellular maintenance during periods of adverse conditions that lead to developmental arrest.

Amino Acid Sequence↗