Characterization of highly frequent epitope-specific CD45RA(+)/CCR7(+/- )T lymphocyte responses against p53-binding domains of the human polyomavirus BK large tumor antigen in HLA-A*0201+ BKV-seropositive donors

Human polyomavirus BK (BKV) has been implicated in oncogenic transformation. Its ability to replicate is determined by the binding of its large tumor antigen (LTag) to products of tumor-suppressor genes regulating cell cycle, as specifically p53. We investigated CD8+ T immune responses to BKV LTag portions involved in p53 binding in HLA-A*0201+ BKV LTag experienced individuals. Peptides selected from either p53-binding region (LTag(351–450 )and LTag(533–626)) by current algorithms and capacity to bind HLA-A*0201 molecule were used to stimulate CD8+ T responses, as assessed by IFN-γ gene expression ex vivo and detected by cytotoxicity assays following in vitro culture. We observed epitope-specific immune responses in all HLA-A*0201+ BKV LTag experienced individuals tested. At least one epitope, LTag(579–587); LLLIWFRPV, was naturally processed in non professional antigen presenting cells and induced cytotoxic responses with CTL precursor frequencies in the order of 1/20'000. Antigen specific CD8+ T cells were only detectable in the CD45RA+ subset, in both CCR7+ and CCR7- subpopulations. These data indicate that widespread cellular immune responses against epitopes within BKV LTag-p53 binding regions exist and question their roles in immunosurveillance against tumors possibly associated with BKV infection

Effects of halothane on transport of 5-hydroxytryptamine by platelet membranes.

Na+-dependent uptake of 5-HT (5-hydroxytryptamine) into plasma membrane vesicles derived from bovine blood platelets and ATP-dependent 5-HT uptake into storage vesicles in platelet lysates were measured. Na+-dependent uptake was temperature-dependent, inhibited by imipramine and exhibited Michaelis-Menten kinetics (apparent Km, 0.12 +/- 0.02 microM; Vmax. 559 +/- 54 pmol/min per mg of protein. Halothane had no effect on Na+-dependent transport of 5-HT in plasma-membrane vesicles. ATP-dependent 5-HT transport into storage granules also exhibited Michaelis-Menten kinetics (apparent Km 0.34 +/- 0.03 microM; Vmax. 34.3 +/- 1.7 pmol/min per mg of protein) and was inhibited by noradrenaline (norepinephrine), but not by imipramine. Exposure of the granules to halothane resulted in a progressive decrease in Vmax. The results demonstrate a possible site for disruption of platelet function by anaesthetics

Sequence conservation in the Saccharomyces and Kluveromyces GAL11 transcription activators suggests functional domains.

Efficient transcription of many Saccharomyces cerevisiae genes requires the GAL11 Protein. GAL11 belongs to a class of transcription activator that lacks a DNA-binding domain. Such proteins are thought to activate specific genes by complexing with DNA-bound proteins. To begin to understand the domain structure-function relationships of GAL11 we cloned and sequenced a homologue from the yeast Kluyveromyces lactis, Kl-GAL11. The two predicted GAL11 proteins show high overall amino acid conservation and an unusual amino acid composition including 18% glutamine, 10% asparagine (S. cerevisiae) or 7% (K. lactis), and 8% proline (K. lactis) or 5% (S. cerevisiae) residues. Both proteins have runs of pure glutamines. Sc-GAL11 has glutamine-alanine runs but in Kl-GAL11 the alanines in such runs are replaced by proline and other residues. The primary sequence similarity is reflected in functional similarity since a gal11 mutation in K. lactis creates phenotypes similar to those seen previously in gal11-defective S. cerevisiae. In addition, Kl-GAL11 complements a gal11-defect in S. cerevisiae by partially restoring induction of GAL1 expression, growth on nonfermentable carbon sources, and phosphorylation of GAL4

A molecular basis for how a single TCR interfaces multiple ligands.

CD8+ T cells respond to Ags when their clonotypic receptor, the TCR, recognizes nonself peptides displayed by MHC class I molecules. The TCR/ligand interactions are degenerate because, in its life time, the TCR interacts with self MHC class I-self peptide complexes during ontogeny and with self class I complexed with nonself peptides to initiate Ag-specific responses. Additionally, the same TCR has the potential to interact with nonself class I complexed with nonself peptides. How a single TCR interfaces multiple ligands remains unclear. Combinatorial synthetic peptide libraries provide a powerful tool to elucidate the rules that dictate how a single TCR engages multiple ligands. Such libraries were used to probe the requirements for TCR recognition by cloned CD8+ T cells directed against Ags presented by H-2Kb class I molecules. When H-2Kb contact residues were examined, position 3 of the peptides proved more critical than the dominant carboxyl-terminal anchor residue. Thus, secondary anchor residues can play a dominant role in determining the antigenicity of the epitope presented by class I molecules. When the four solvent-exposed potential TCR contact residues were examined, only one or two of these positions required structurally similar residues. Considerable structural variability was tolerated at the remaining two or three solvent-exposed residues of the Kb-binding peptides. The TCR, therefore, requires close physico-chemical complementarity with only a few amino acid residues, thus explaining why TCR/MHC interactions are of low affinity and degenerate

Sip1 Is a Catabolite Repression-Specific Negative Regulator of Gal Gene Expression

The yeast Snflp kinase is required for normal expression of amny genes involved in utilization of non-glucose carbon. Snflp is known to associate with several proteins. One is Sip1p, a protein that becomes phosphorylated in the presence of Snflp and thus is a candidate Snflp kinase substrate. We have isolated the SIP1 gene as a multicopy suppressor of the gal83-associated defect in glucose repression of GAL gene expression. Multicopy SIP1 also suppressed the gal82-associated defect in glucose repression, suggesting that SIP1, GAL83 and GAL82 function interdependently. Multicopy SIP1 gene reduces GAL1, GAL2, GAL7 and GAL10 gene expression three- to fourfold in cells grown in the presence of glucose but has no effect in cells grown on nonrepressing carbon. Sip1-deletion cells exhibited a two- to threefold increase in GAL gene expression compared to wild-type cells when grown on glucose. These studies show that SIP1 is a catabolite repression-specific negative regulator of GAL gene expression. Northern analysis revealed two SIP1 transcripts whose relative abundance changed with carbon source. Western blots revealed that Sip1p abundance is not markedly affected by carbon source, suggesting that Sip1p may be regulated post-translationally

Report: Analysis of beta-2 microglobulin (b2M), free HLA class I heavy chain (FHC) and the associated protein pattern in multiple myeloma (MM) patients from the Nordic Myeloma Group Study.

Background. Autologous stem cell transplantation is now considered the standard of care in young patients with multiple myeloma (MM) and the most consistent prognostic factor described at diagnosis has been blood levels of beta-2 microglobulin ((32m). Recently, the levels of (32mfree HLA class I heavy chain (FHC) has been shown to correlate with P2m but as expected not influenced by renal failure seen in MM. These data indicate that serum FHC may be a more useful disease marker than P2m in MM. The aim of this study was to evaluate the prognostic impact of FHC in a cohorde of 102 patients included in the NMSG study #5/94 and to identify B2m and/or FHC associated protein expression patterns identified by global array analysis by surface-enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI-TOF-MS). Methods. Serum samples from 102 patients with MM undergoing high dose therapy and autologous stem cell transplantation were retrospectively analyzed for concentration of B2m and FHC. The serum specimens were further evaluated by surface-enhanced laser desorption/ionization time-offlight mass spectrometry (SELDI-TOF-MS) to profile protein expression up to 20 kDa. Results. Serum 02m and FHC was correlated and B2rn but not FHC was found to be a most significant predictor ot overall survival. Using the SELDI technique with prefractiortation of samples before profiling, we identified mass spectrometry peaks significantly correlated to 132m and FHC and such circulating biomarkers with a likely pathophysiological role may be used as predictors of outcome. Conchtsiort. Data from this study did not confirm FHC as a prognostic variable indicating that the prognostic impact ot turn levels is not only a tumour marker but also an indirect consequence of other disease ielateci events including impaired kidney or other organ function as well as host-tumour interactions. The feasibility of a chip-based proteomic profiling technique to identify plasma proteins of prognostic significance will be demonstrated