Wild-type estrogen receptor beta expression in normal and neoplastic paraffin-embedded tissues.

Recently, several antibodies have allowed the detection of estrogen receptor beta (ER-beta) in paraffin-embedded tissue; however, these attempts have failed to specifically identify the wild-type form and revealed technical difficulties such as the necessity for alterations to standard staining protocols and amplification detection systems. The aim of this study was to generate a monoclonal antibody that could provide enhanced sensitivity for detection of ER-beta in paraffin embedded tissues. A 130-amino acid region of the C-terminus of ER-beta was expressed as a fusion protein and used as an antigen to generate monoclonal antibodies. Immunohistochemical analysis of ER-beta using clone EMR02 in normal and inflamed tissues demonstrated nuclear staining. In benign and malignant tumors, variable intensities of staining and patterns of nuclear reactivity were observed between cases. Intense ER-beta positivity was also observed in tumor-infiltrating lymphocytes. Mapping studies by ELISA and Western blotting have identified specific reactivity of EMR02 to a 17-amino acid sequence of the full-length wild-type ER-beta protein (ERbetawt). Our results show that clone EMR02 is a sensitive tool for the detection of ERbetawt in paraffin-embedded tissues. This preliminary study also supports its use in immunohistochemical studies to determine the role of ERbetawt as a tumor prognostic marker and a possible therapeutic target.

Production of Bacillus anthracis protective antigen is dependent on the extracellular chaperone, PrsA.

Protective antigen (PA) is a component of the Bacillus anthracis lethal and edema toxins and the basis of the current anthrax vaccine. In its heptameric form, PA targets host cells and internalizes the enzymatically active components of the toxins, namely lethal and edema factors. PA and other toxin components are secreted from B. anthracis using the Sec-dependent secretion pathway. This requires them to be translocated across the cytoplasmic membrane in an unfolded state and then to be folded into their native configurations on the trans side of the membrane, prior to their release from the environment of the cell wall. In this study we show that recombinant PA (rPA) requires the extracellular chaperone PrsA for efficient folding when produced in the heterologous host, B. subtilis; increasing the concentration of PrsA leads to an increase in rPA production. To determine the likelihood of PrsA being required for PA production in its native host, we have analyzed the B. anthracis genome sequence for the presence of genes encoding homologues of B. subtilis PrsA. We identified three putative B. anthracis PrsA proteins (PrsAA, PrsAB, and PrsAC) that are able to complement the activity of B. subtilis PrsA with respect to cell viability and rPA secretion, as well as that of AmyQ, a protein previously shown to be PrsA-dependent.