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PubMedDate not supplied

Prothymosin alpha-receptor associates with lipid rafts in PHA-stimulated lymphocytes.

Lipid rafts are specialized plasma membrane microdomains in which glycosphingolipids and cholesterol are major structural components. Their relative insolubility to nonionic detergents is the most widely used method to purify these structures. Several signalling proteins are associated with these microdomains in T lymphocytes, including receptors for growth factors and cytokines. ProTalpha is a highly conserved and widely distributed protein whose physiological functions remain elusive. In previous works we identified, by means of affinity cross-linking, affinity chromatography and fluorescence microscopy, a set of binding proteins for ProTalpha in human lymphoblasts. Now, this work goes deeply in that ProTalpha receptor description revealing, by different experimental approaches, its presence in lipid rafts. Moreover, our results fit a model in which a tyrosine phosphorylation signalling cascade confined to rafts is initiated upon ProTalpha receptor recognition, which represents an important and promising finding in the research for elucidating the molecular mechanisms underlying the immunomodulatory functions of ProTalpha.

Antigens, CD↗
PubMed1990

Defective uptake of alpha-fetoprotein (AFP) and transferrin (Tf) by PHA-activated peripheral blood lymphocytes from patients with AIDS and related syndromes.

Serum alpha-fetoprotein (AFP) and transferrin (Tf) are actively endocytosed by many growing cells during ontogenic and neoplastic growth, but also by peripheral T lymphocytes upon mitogen activation. AFP and Tf uptake occurs through receptor-mediated endocytosis. The purpose of the present work was to assess whether the expression and functional activity of AFP and Tf receptors are impaired in mitogen-activated T cells from several groups of HIV-1 seropositive (HIV+) individuals. Forty HIV+ cases were studied, including 12 patients with AIDS, 12 with lymphoadenopathy syndrome (LAS), as well as 16 asymptomatic homosexuals (As). Quantification of AFP and Tf uptake was carried out by fluorescence-activated cell sorting (FACS) using fluoresceinated derivatives of these proteins. Compared with healthy blood donors, the three HIV-1 seropositive groups exhibited clear impairment in the ability of their peripheral blood mononuclear cells (PBMC) to internalize AFP and Tf. The decrease in mean values of AFP uptake correlates roughly with the severity of the clinical status. Although these observations need to be confirmed after a much wider study groups, the AFP-Tf-endocytosis assay presented here clearly reveals early defective functions of mitogen-responsive T cells in disease-free subjects and may provide the basis for a prognostic test. The pathophysiological implications of these facts are discussed in relation to the structural and/or metabolic activities of fatty acids and iron, the ligands carried by AFP and Tf, respectively.

AIDS-Related Complex↗
PubMed1994

Effect of four i.v. induction agents on T-lymphocyte proliferations to PHA in vitro.

Anaesthetic agents are believed to have an adverse effect on human immunity. We have studied the effects of four i.v. induction agents, thiopentone, methohexitone, etomidate and propofol, on T-lymphocyte proliferations to phytohaemagglutinin in vitro. We found that at plasma concentrations similar to those obtained after induction doses, all drugs, with the exception of propofol, caused depression of T-lymphocyte function.

Anesthetics, Intravenous↗
PubMedDate not supplied

Organization of rodent auditory cortex: anterograde transport of PHA-L from MGv to temporal neocortex.

In the present study we analyzed the organization of the thalamocortical projections of the specific auditory relay nucleus of the thalamus, the ventral division of the medial geniculate body (MGv), using the anterograde axonal tracer Phaseolus vulgaris leucoagglutinin. All injections of MGv produced dense labeling of axonal fibers in temporal cortex. In all cases, labeled axons were predominantly concentrated in cortical layers III and IV and, to a lesser extent, at the junction of layers V and VI. Injections confined to the medial regions of MGv, and specifically to the ovoid nucleus of MGv (OV, pars ovoidea), resulted in anterograde labeling of TE1, with minor labeling of the ventral quarter of TE1, designated subarea TE1v. Injections placed in lateral regions of MGv and occupying the lateral ventral subnucleus (LV), or injections in the mediolateral center of MGv and occupying parts of LV and OV, also resulted in labeling of area TE1 and minor labeling of TE1v. However, these injections also produced labeling in areas TE2 and TE3. Thus, area TE1 (excluding subarea TE1v) receives heavy projections from all aspects of MGv and appears to be the core target of MGv. While regions of MGv also project to surrounding cortical belt areas, these projections tend to be lighter and to vary depending on the region of MGv examined. These results, together with other connectional findings, and cytoarchitectonic and physiological studies, suggest that TE1 (possibly excluding subarea TE1v) is the primary auditory cortex in the rat.

Animals↗
PubMed2005

Influence of homologous phasins (PhaP) on PHA accumulation and regulation of their expression by the transcriptional repressor PhaR in Ralstonia eutropha H16.

Phasins play an important role in the formation of poly(3-hydroxybutyrate) [poly(3HB)] granules and affect their size. Recently, three homologues of the phasin protein PhaP1 were identified in Ralstonia eutropha strain H16. The functions of PhaP2, PhaP3 and PhaP4 were examined by analysis of R. eutropha H16 deletion strains (DeltaphaP1, DeltaphaP2, DeltaphaP3, DeltaphaP4, DeltaphaP12, DeltaphaP123 and DeltaphaP1234). When cells were grown under conditions permissive for poly(3HB) accumulation, the wild-type strain and all single-phasin negative mutants (DeltaphaP2, DeltaphaP3 and DeltaphaP4), with the exception of DeltaphaP1, showed similar growth and poly(3HB) accumulation behaviour, and also the size and number of the granules were identical. The single DeltaphaP1 mutant and the DeltaphaP12, DeltaphaP123 and DeltaphaP1234 mutants showed an almost identical growth behaviour; however, they accumulated poly(3HB) at a significantly lower level than wild-type and the single DeltaphaP2, DeltaphaP3 or DeltaphaP4 mutants. Gel-mobility-shift assays and DNaseI footprinting experiments demonstrated the capability of the transcriptional repressor PhaR to bind to a DNA region +36 to +46 bp downstream of the phaP3 start codon. The protected sequence exhibited high similarity to the binding sites of PhaR upstream of phaP1, which were identified recently. In contrast, PhaR did not bind to the upstream or intergenic regions of phaP2 and phaP4, thus indicating that the expression of these two phasins is regulated in a different way. Our current model for the regulation of phasins in R. eutropha strain H16 was extended and confirmed.

Bacterial Proteins↗