The polyclonal antibody responses of Lewis rats to the synthetic encephalitogenic neuropeptide S55S (residues 72-84 of guinea pig myelin basic protein) and its analogs

The yeast RME1 gene encodes a putative zinc finger protein that is directly repressed by a1-alpha 2

In the yeast Saccharomyces cerevisiae, a/alpha cells can enter meiosis whereas a and alpha cells cannot. The a/alpha cell type is determined by presence of a repressor, a1-alpha 2. Previous studies indicate that a/alpha cells lack an inhibitor of meiosis, the RME1 gene product, and that a and alpha cells express RME1. We report here the sequence of RME1 and functional analysis of its regulatory and coding regions. The 5'-region of RME1 includes a sequence resembling a1-alpha 2 repression sites. Deletion of this site at RME1 relieves repression by a1-alpha 2, and insertion of the site into a heterologous regulatory region (CYC1) confers weak repression in a/alpha cells. These observations indicate that RME1 is directly repressed by a1-alpha 2. The RME1 product has three regions that resemble C2H2 zinc fingers, which are characteristic of a class of nucleic-acid-binding proteins. Substitution of serine for cysteine in each of the putative fingers abolishes RME1 function; serine substitutions in the second and third putative fingers do not affect RME1 stability. These findings indicate that at least two putative zinc fingers are critical for RME1 structure or activity. Therefore RME1, which is formally a negative regulator of the meiotic gene IME1, may act directly as a repressor.

Defective T helper cell epitope responsible for the failure of region 69-84 of the human myelin basic protein to induce experimental allergic encephalomyelitis in the Lewis rat

Studies from our laboratory have shown that region 69-84 (synthetic peptide S49S) of myelin basic protein (MBP) defines an encephalitogenic sequence for experimental allergic encephalomyelitis (EAE) in Lewis rats. The most potent EAE inducers are the guinea pig MBP (Gp-MBP) and region 69-84, known as synthetic peptide Gp-S49S: (See text: formula). Human (H-MBP) was considerably less potent than Gp-MBP, and region 69-84 (H-S49S) of H-MBP did not induce hind leg paralysis or any histological signs of EAE. Since the development of EAE requires the expression of specific T and B cell epitopes, sequence analysis of H-S49S and Gp-S49S revealed phylogenetic variations in the H-S49S sequence, characterized by positions 77 and 78, and substitution of Ser with Thr at position 80: (See text: formula). Like Gp-S49S, peptide H-S49S induced the formation of antibodies with specificities directed against the C-terminal of the H-S49S, Gp-S49S, and homologous sequences. In contrast to Gp-S49S, neither II-S49S nor shorter peptides induced clonal T cell expansion when either of the peptides was added to encephalitogenic T cell clone D in culture. Clone D, which expresses T helper phenotype, was selected from encephalitogenic peptide-primed Lewis rats. The results of the study show that the failure of H-S49S to induce EAE is related to sequence alterations in the T helper cell epitope but not in the B cell epitope located in the N- and C-terminal portions of the S49S sequence, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Role of antibodies in T cell-mediated experimental allergic encephalomyelitis

The role of the humoral phase of the immune response in development of T cell-mediated experimental allergic encephalomyelitis (EAE) had not been clearly defined previously even though studies of the myelin basic protein (MBP) molecule had demonstrated the presence not only of T cell but also B cell epitopes capable of inducing cell-mediated immunity and antibody formation. Particularly relevant to this report are the immunological expressions of the region which induces EAE in the Lewis rat. The development of primary demyelination in Lewis rats is preceded by a cell-mediated immune response as well as antibody formation, both of which are highly specific to the encephalitogenic 14-residue peptide that defines the 69-84 region of the parent MBP. Our results are consistent with the dogma that EAE is a T cell-mediated disease, but they also clearly demonstrate an important role for specific antibodies in the development of these T cells responsible for demyelination. The antibody response, which may be heteroclitic, is necessary for T cells to develop into an effector T cell subset. Without this B cell response the subsequent T cell response does not lead to demyelination. In this report we shall discuss these findings and further show that the T cell and B cell epitopes, which are located within the 14-residue sequence, are physically separated and dependent upon the form of synthetic peptides known to induce T cell-mediated and/or humoral immunity.(ABSTRACT TRUNCATED AT 250 WORDS)