Expression and pharmacological characterization of the human μ-opioid receptor in the methylotrophic yeast Pichia pastoris

AbstractThe human μ-opioid receptor cDNA from which the 32 amino-terminal codons were substituted by the Saccharomyces cerevisiae α-mating factor signal sequence has been expressed in the methylotrophic yeast Pichia pastoris using the host promoter of the alcohol oxidase-1 gene. Cell membranes exhibited specific and saturable binding of the opioid antagonist [3H]diprenorphine (Kd = 0.2 nM and Bmax = 400 fmol/mg protein or 800 sites/cell). Competition studies with non-selective, and μ-, δ- and κ-selective opioid agonists and antagonists revealed a typical μ-opioid receptor binding profile, suggesting proper folding of the protein in yeast membranes

Lipid-restricted recognition of mycobacterial lipoglycans by human pulmonary surfactant protein A: a surface-plasmon-resonance study.

The human pulmonary surfactant protein A (hSP-A), a member of the mammalian collectin family, is thought to play a key defensive role against airborne invading pulmonary pathogens, among which is Mycobacterium tuberculosis, the aetiologic agent of tuberculosis. hSP-A has been shown to promote the uptake and the phagocytosis of pathogenic bacilli through the recognition and the binding of carbohydrate motifs on the invading pathogen surface. Recently we identified lipomannan and mannosylated lipoarabinomannan (ManLAM), two major mycobacterial cell-wall lipoglycans, as potential ligands for binding of hSP-A. We demonstrated that both the terminal mannose residues and the fatty acids are critical for binding, whereas the inner arabinosyl and mannosyl domains do not participate. In the present study we developed a surface-plasmon-resonance assay to analyse the molecular basis for the recognition of ManLAM by hSP-A and to try to define further the role of the lipidic aglycone moiety. Binding of ManLAM to immobilized hSP-A was consistent with the simplest one-to-one interaction model involving a single class of carbohydrate-binding site. This observation strongly suggests that the lipid moiety of ManLAM does not directly interact with hSP-A, but is rather responsible for the macromolecular organization of the lipoglycan, which may be necessary for efficient recognition of the terminal mannosyl epitopes. The indirect, structural role of the lipoglycan lipidic component is further supported by the complete lack of interaction with hSP-A in the presence of a low concentration of mild detergent

Mouse Vα14i natural killer T cells are resistant to cytokine polarization in vivo

Under different circumstances, natural killer T (NKT) cells can cause a T helper (Th) 1 or a Th2 polarization of immune responses. We show here, however, that mouse NKT cells with an invariant Vα14 rearrangement (Vα14i NKT cells) rapidly produce both IL-4 and IFN-γ, and this pattern could not be altered by methods that polarize naive CD4(+) T cells. Surprisingly, although cytokine protein was detected only after activation, resting Vα14i NKT cells contained IL-4 and IFN-γ mRNAs. Despite this finding, in vivo priming of mice with the glycolipid antigen recognized by Vα14i NKT cells resulted in a more Th2-oriented response upon antigen re-exposure. The Vα14i NKT cells from primed mice retain the ability to produce IL-4 and IFN-γ, but they are less effective at activating NK cells to produce IFN-γ. Our data therefore indicate that Vα14i NKT cells have a relatively inflexible immediate cytokine response, but that changes in their ability to induce IFN-γ secretion by NK cells may determine the extent to which they promote Th1 responses

CD1d-restricted peripheral T cell lymphoma in mice and humans

International audiencePeripheral T cell lymphomas (PTCLs) are a heterogeneous entity of neoplasms with poor prognosis, lack of effective therapies, and a largely unknown pathophysiology. Identifying the mechanism of lymphomagenesis and cell-of-origin from which PTCLs arise is crucial for the development of efficient treatment strategies. In addition to the well-described thymic lymphomas, we found that p53-deficient mice also developed mature PTCLs that did not originate from conventional T cells but from CD1d-restricted NKT cells. PTCLs showed phenotypic features of activated NKT cells, such as PD-1 up-regulation and loss of NK1.1 expression. Injections of heat-killedStreptococcus pneumonia, known to express glycolipid antigens activating NKT cells, increased the incidence of these PTCLs, whereasEscherichia coliinjection did not. Gene expression profile analyses indicated a significant down-regulation of genes in the TCR signaling pathway in PTCL, a common feature of chronically activated T cells. Targeting TCR signaling pathway in lymphoma cells, either with cyclosporine A or anti-CD1d blocking antibody, prolonged mice survival. Importantly, we identified human CD1d-restricted lymphoma cells within Vδ1 TCR-expressing PTCL. These results define a new subtype of PTCL and pave the way for the development of blocking anti-CD1d antibody for therapeutic purposes in human