A monoclonal antibody, 3G12, reacts with a novel surface molecule, Hal-1, with high expression in CD30-positive anaplastic large cell lymphomas

Localization and function in endoplasmic reticulum stress tolerance of ERdj3, a new member of Hsp40 family protein

Heat shock protein 40 (Hsp40) family proteins are known to bind to Hsp70 through their J-domain and regulate the function of Hsp70 by stimulating its adenosine triphosphatase activity. In the endoplasmic reticulum (ER), there are 5 Hsp40 family proteins known so far, 3 of which were recently identified. In this report, one of the novel Hsp40 cochaperones, ERdj3, was characterized in terms of its subcellular localization, stress response, and stress tolerance of cells. By using ERdj3-specific polyclonal antibody, endogenous ERdj3 protein was shown to reside in the ER as gene transfer-mediated exogenous ERdj3. Analysis of the expression level of endogenous ERdj3 protein revealed its moderate induction in response to various ER stressors, indicating its possible action as a stress protein in the ER. Subsequently, we analyzed whether this molecule was involved in ER stress tolerance of cells, as was the case with the ER-resident Hsp70 family protein BiP. Although overexpression of ERdj3 by gene transfection could not strengthen ER stress tolerance of neuroblastoma cells, reduction of ERdj3 expression by small interfering ribonucleic acid decreased the tolerance of cells, indicating that ERdj3 might have just a marginal role in the ER stress resistance of neuroblastoma cells. In contrast, overexpression of ERdj3 notably suppressed vero toxin-induced cell death. These data suggest that ERdj3 might have diverse roles in the ER, including that of the molecular cochaperone of BiP and an as yet unknown protective action against vero toxin.

The expression of a novel natural killer inhibitory molecule, Cho-1, on the chorionic cytotrophoblast cells of successful pregnancy, but not of spontaneous abortion

The regulatory mechanism of the recognition and cytotoxicity by natural killer (NK) cells in placental tissue remains unclarified. Previous reports indicated that monoclonal antibody Cho-1-defined molecule (Cho-1 molecule) may act as the negative regulator in the cytotoxicity by human NK cells. The Cho-1 molecule is composed of non-covalently associated cell surface molecules of approximately 200 kDa and 40 kDa. In the present study we analyzed the expression of this novel molecule in extravillous cytotrophoblast cells, which are presumed to be exposed to the cytotoxic action by maternal NK cells, from clinical cases of successful pregnancy and spontaneous abortion. By using monoclonal antibody Cho-1, our immunohistochemical data indicated that the Cho-1 molecule is clearly expressed in the cytotrophoblast cells of the early phase of successful pregnancy, but only weakly expressed in those from spontaneous abortion. The cytotrophoblast cells in the late phase (9-10 months) of pregnancy also expressed this molecule. Fluorescence-activated cell sorter analysis also showed that it is expressed on the cytotrophoblast cell surface of successful pregnancy but not on that of spontaneous abortion, suggesting that Cho-1 antigen may act as a negative regulator of the cytotoxicity by NK cells in successful pregnancy of the fetus.