Effects of N-glycan processing inhibitors on signaling events and induction of apoptosis in galectin-1-stimulated Jurkat T lymphocytes.

To elucidate the role of N-linked glycans in triggering T-cell functions, the effects of the N-glycan processing inhibitors 1-deoxymannojirimycin (1-DMM) and swainsonine (SW) were investigated on signaling events and induction of apoptosis in galectin-1 (gal-1)-stimulated Jurkat T lymphocytes. The treatment of Jurkat E6.1 cells with 1-DMM and SW strongly reduced the cell binding of gal-1-biotin, conjugate binding to cell lysate glycoproteins, and to cluster of differentiation (CD) 3 immunoprecipitates on blots as well as the binding of CD2 and CD3 to immobilized gal-1.

Profiling of early gene expression induced by erythropoietin receptor structural variants.

The development of erythroid progenitor cells is triggered via the expression of the erythropoietin receptor (EPOR) and its activation by erythropoietin. The function of the resulting receptor complex depends critically on the presence of activated JAK2, and the complex contains a large number of signaling molecules recruited to eight phosphorylated tyrosine residues. Studies using mutant receptor forms have demonstrated that truncated receptors lacking all tyrosines are able to support red blood cell development with low efficiency, whereas add-back mutants containing either Tyr343 or Tyr479 reconstitute EPOR signaling and erythropoiesis in vivo.

Phosphoprotein profiling of erythropoietin receptor- dependent pathways using different proteomic strategies.

Proteomic techniques provide new tools for the global analysis of protein profiles but also for the investigation of specific protein functions. The analysis of signaling cascades has traditionally been performed by the determination of enzymatic or transcription factor activities representing a certain pathway. Functional proteomics now allows more comprehensive approaches to study cellular responses induced during ligand/receptor interactions.

Effects of galectin-1 on regulation of progesterone production in granulosa cells from pig ovaries in vitro.

The detection of galectin-1 (gal-1) in pig granulosa cell lysates by immunoblotting and its cytosolic as well as membrane-associated localization prompted us to study its effects on cell proliferation and regulation of progesterone synthesis. The lectin stimulated the proliferation of granulosa cells from pig ovaries cultured in serum-free medium. Gal-1 inhibited the FSH-stimulated progesterone synthesis of granulosa cells.

FTY720 prevents anti-CD4 mAb-induced tolerance but cannot reverse established tolerance in a rat kidney transplantation model.

FTY720 is highly effective in various models of transplantation and autoimmunity. In order to find drugs that act synergistically with a tolerance-inducing nondepleting anti-CD4 mAb we studied this combination in a strong DA to LEW kidney transplantation model. Rats were treated with 0.

Bag-1 up-regulation in anti-CD4 mAb-treated allo-activated T cell confers resistance to activation-induced cell death (AICD).

The non-depleting anti-CD4 monoclonal antibody (mAb) RIB5/2 is a powerful inducer of tolerance to major histocompatibility complex (MHC)-incompatible allografts in rat recipients. The unresponsiveness induced is characterized by the persistence (over 300 days) of donor-reactive regulatory T cells within the graft. We applied differential-display reverse-transcription polymerase chain reaction (RT-PCR) to identify differences at the mRNA level between graft-infiltrating cells of anti-CD4 mAb-treated and non-treated control rats at day 5 after kidney transplantation.

Galectin-induced activation of the transcription factors NFAT and AP-1 in human Jurkat T-lymphocytes.

Galectin-mediated ligation of glycoepitopes on T-cell activation markers induces an increase in the cytosolic calcium concentration ([Ca(2+)](i)) originating from a transient Ca(2+) release of internal stores as well as a sustained influx across the plasma membrane. In transiently transfected Jurkat T-lymphocytes, galectins [galectin-1 (gal-1), recombinant human galectin-1 (rec gal-1), nematode 32-kDa galectin (LEC-1), nematode 16-kDa galectin (LEC-6)] differentially stimulate the expression of the luciferase reporter gene constructs pNFAT-TA-Luc and pAP1(PMA)-TA-Luc, which are activated by the nuclear factor of activated T-cells (NFAT) or the transcription factor, activator protein 1 (AP-1), respectively. The galectin-stimulated expression of the reporter constructs is completely inhibited by lactose (30 mM) and asialofetuin (30 microM) carrying Galbeta1-4GlcNAc sequences.

Interferon-alpha inhibits cell cycle progression by Ba/F3 cells through the antagonisation of interleukin-3 effects on key regulators of G(1)/S transition.

The molecular mechanisms of interferon-alpha (IFN-alpha)-mediated cell growth inhibition are incompletely understood. Here, we have analysed how IFN-alpha interferes with the interleukin-3 (IL-3)-stimulated cell cycle progression by Ba/F3 cells. The antiproliferative cytokine caused a delay in cell cycle progression, which correlated with a diminished activation of the cyclin-dependent kinases 2 and 4 in IL-3-stimulated cells.

Bone morphogenetic protein-7 (OP1) and transforming growth factor-beta1 modulate 1,25(OH)2-vitamin D3-induced differentiation of human osteoblasts.

Bone morphogenetic proteins (BMPs) and transforming growth factor-beta (TGFbeta) are potent regulators of osteoblast differentiation and proliferation, processes that are crucial in bone remodeling. BMPs and TGFbeta act in concert with other local factors and hormones, among them 1,25(OH)2-vitamin D3 and insulin. Here we show that BMP7 inhibits 1,25(OH)2-vitamin D3-induced differentiation of human osteoblasts, whereas TGFbeta1 stimulates it, as assessed by assays for alkaline phosphatase (ALP) induction, matrix mineralization, and morphology changes.

Bag-1 up-regulation in anti-CD4 mAb treated allo-activated T cells confers resistance to apoptosis.

The non-depleting anti-CD4 mAb RIB5/2 is a powerful inducer of tolerance to MHC-incompatible renal and heart allografts in rat recipients. In vitro the mAb blocks the proliferation and cytokine production of alloreactive T cells. To learn more about the mechanism of anti-CD4-mediated suppression, we applied differential display reverse transcription-PCR to identify differences at mRNA level between T cells stimulated by alloantigen in the presence or absence of anti-CD4 mAb.