The influence of maternally transmitted immunoglobulins on the development of autoimmune diabetes mellitus in genetically susceptible human progeny remains unknown. Given the presence of islet beta cell-reactive autoantibodies in prediabetic nonobese diabetic (NOD) mice, we abrogated the maternal transmission of such antibodies in order to assess their influence on the susceptibility of progeny to diabetes. First, we used B cell-deficient NOD mothers to eliminate the transmission of maternal immunoglobulins. In a complementary approach, we used immunoglobulin transgenic NOD mothers to exclude autoreactive specificities from the maternal B-cell repertoire. Finally, we implanted NOD embryos in pseudopregnant mothers of a non-autoimmune strain. The NOD progeny in all three groups were protected from spontaneous diabetes. These findings demonstrate that the maternal transmission of antibodies is a critical environmental parameter influencing the ontogeny of T cell-mediated destruction of islet beta cells in NOD mice. It will be important to definitively determine whether the transmission of maternal autoantibodies in humans affects diabetes progression in susceptible offspring.

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We have produced bcl-2 transgenic mice by using a construct which mimics the t(14;18) translocation in human follicular lymphomas. Although lymphoid tissues from all transgenic mice contained hih levels of human Bd-2 protein, transgene expression was differentially regulated within the B-and T-cell compartments of ies derived from various founder mice. We have characterized the phenotypes of two lines of bcI-2 transgenic mice ie 2 and line 6) in which bcl-2 transgene expression was restricted primarily to the T-or B-cell lineages, respectively. Analysis of line 6 lymphocytes revealed a polyclonal expansion of B cells, and these B cells exhibited prolonged survival in vitro. In line 2 mice, numbers of T cells in the peripheral lymphoid tissues were more moderately elevated despite enhanced T-cell survial in vitro. Line 2 transgenic mice also showed significantly increased proportions of thymocytes with a mature phenotype. Taken together, these findings suggest different roles for bdl-2 in the in vivo regulation of B-and T-cell development and homeostasis.The t(14;18)(q32;q21) chromosomal translocation is one of the most common cytogenetic abnormalities in lymphoid malignancies, and it occurs in the majority of non-Hodgkin B-cell lymphomas (1, 2). This translocation juxtaposes the BCL2 protooncogene at chromosome 18q21 with the immunoglobulin heavy-chain (IGH) locus at 14q32, resulting in abnormally high levels of BCL2 gene transcription, probably due to the influence of an enhancer located within the IGH J-C intron. The 26-kDa product of the BCL2 gene has been reported to be localized to the inner mitochondrial membrane (3), but it may also bind to other, as-yet-undefined, structures in a cell-cycle-dependent manner. Bcl-2 is unique among oncogene products in that it appears to enhance lymphoid cell survival by interfering with programmed cell death (also known as apoptosis), rather than promoting cell proliferation (4-7). Though originally discovered because of its involvement in B-cell lymphomas, the BCL2 gene is normally expressed in both mature B and T cells. As a first step toward defining the in vivo functions of BCL2 in B and T cells, we created several lines of transgenic mice containing a construct that resembles the t(14;18) translocation. Here we describe the effects of bcl-2 transgene expression on T-and B-cell homeostasis and survival in two strains of bcl-2 transgenic mice which display T-or B-cell-restricted transgene expression. MATERIALS AND METHODSConstruction of Human BCL2/IGH Minilocus. A DNA construct for microinjection was subcloned from human genomic sequences ofBCL2 and the IGH loci (8-10) (Fig. 1).For production of transgenic mice, a 13-kb DNA fragment was isolated from the final plasmid by BssHII digestion, gel-purified, and dialyzed against modified TE buffer (0.1 mM EDTA/10 mM Tris-HCl, pH 7.5).Production of Transgenic Mice. Approximately 250-500 copies of the construct were microinjected into the male pronucleus of(SWR/J x SJL/J)Fl fertilized eggs by standard methods (11). Int...

The HER2 gene encodes the receptor tyrosine kinase HER2 and is often over-expressed or amplified in breast cancer. Up-regulation of HER2 contributes to tumor progression. Many aspects of tumor growth are favorably affected through activation of HER2 signaling. Indeed, HER2 plays a role in increasing proliferation and survival of the primary tumor and distant lesions which upon completion of full transformation cause metastases. P185HER2/neu receptors and signaling from them and associated molecules lead to increase motility of both intravasating and extravasating cells, decreasing apoptosis, enhancing signaling interactions with the microenvironment, regulating adhesion, as well as a multitude of other functions. Recent experimental and clinical evidence supports the view that spread of incompletely transformed cells occurs at a very early stage in tumor progression. This review concerns the identification and characterization of HER2, the evolution of the metastasis model, and the more recent cancer stem cell model. In particular, we review the evidence for an emerging mechanism of HER2+ breast cancer progression, whereby the untransformed HER2-expressing cell shows characteristics of stem/progenitor cell, metastasizes, and then completes its final transformation at the secondary site.

The bcI-2 gene, which is overexpressed in human follicular B-cell lymphomas, has been found to extend ceflular lifespan through Inhibition of apoptosis, or programmed cell death. However, the physiological role of the Bcd-2 protein In lymphocyte development is unclear. We have established a transgenic mouse line that expresses high levels of the Bcd-2 protein in both cortical and medulary thymocytes, disrupting the normal pattern of expression of this gene. We found that in these mice, immature thymocytes became resistant to apoptosis mediated by corticosterolds and calcium ionophores. Untreated thymocytes also exhibited a survival advantage in suspension cultures compared with controls. In addition, overexpression of bcI-2 enabled a proportion of thymocytes and peripheral T cells to escape the process of clonal deletion, which normally eliminates self-reactive T cells during thymocyte maturation. These findings implicate the Bcl-2 protein in regulating the lifespan of maturing thymocytes and in the antigenic-selection process.In most human follicular lymphomas, the BCL2 gene is overexpressed as a result of chromosomal translocation into the immunoglobulin heavy chain locus (1-3). The p26 Bcl-2 protein is expressed in intracellular membranes, particularly within mitochondria (4). Overexpression of bcl-2 in cell lines has been found to extend cellular survival without inducing proliferation by inhibiting programmed cell death, also termed apoptosis (4, 5). During T-cell development, thymocytes mature from short-lived, steroid-sensitive CD4+CD8+ cells into very long-lived, steroid-resistant CD4-CD8+ or CD4+CD8-mature T cells. CD4+CD8' thymocytes that are not selected to mature rapidly disappear from the thymus, probably as a result of programmed cell death (6-8). Although bcl-2 expression is normally restricted to the mature T cells in the thymic medulla that have survived thymic selection (9, 10), it is not known whether this pattern of expression contributes to the lifespan changes during thymocyte development. To better understand the contribution of bcl-2 to T-cell development, we studied the phenotype of transgenic mice expressing high levels of the human Bcl-2 protein in thymocytes and peripheral T cells.MATERIALS AND METHODS Transgenic Mice. The transgene construct contained portions of the human BCL2 gene and a t(14;18) breakpoint region with the immunoglobulin heavy chain enhancer. (SWR x SJL) F1 transgenic mice were generated as described (11) and propagated on an SWR background. Transgenic status was routinely determined by PCR analysis of tail lysates using bcl-2-and joining region of the heavy chain-specific primers (12). The expression of the bcl-2 transgene was monitored by immunoblot and immunohistochemical assays (12, 13).Induction and Analysis of Thymocyte Apoptosis. Mice were injected i.p. with dexamethasone (Dex) at 50 mg/kg in phosphate-buffered saline, or phosphate-buffered saline alone. Forty-eight hours later, thymocyte cell suspensions were prepared for fluorescence-activated cell ...