Expression of vav proto-oncogene by nonhematopoietic trophoblast cells at the human uteroplacental interface

Comparison of c-DNA microarray analysis of gene expression between eutopic endometrium and ectopic endometrium (endometriosis)

PROBLEM

As recent studies have suggested abnormalities in the regulation of specific genes in the development of endometriosis, we investigated differentially expressed genes in endometriosis compared to endometrium.

METHOD OF STUDY

Gene expression profiles using the Atlas microarray were performed in endometriotic tissue and endometrium. Nine of the 13 genes of endometriotic tissue showed an up-regulation in relation to endometrium and four of the 13 genes a down-regulation.

RESULTS

Of the 1176 genes on the Atlas Human 1,2 array, only 13 differentially expressed identical genes were detected after repeating the gene analysis three times.

CONCLUSION

According to our c-DNA analysis some differentially expressed genes may be involved in the pathogenesis of endometriosis. An imbalance in the genes responsible for the reproductive process may lead to a decrease in embryo implantation in patients with endometriosis.

Placental endogenous retrovirus (ERV): structural, functional, and evolutionary significance

That endogenous retrovirus (ERV) is present within the placenta of humans and other mammals has been known for the past 25 years, but the significance of this observation is still not fully understood. Much molecular biological data have emerged in recent years to support the earlier electron microscopic data on the presence of placental ERV. The evidence for ERV in animal and human placental tissue is presented, then integrated with data on the presence of ERV in a range of other tissues, in particular teratocarcinoma cells. Placental invasiveness and maternal immunosuppression are then discussed in relation to metalloproteinase secretion, the immunosuppressive potential of retroviruses, and placental growth factors, while the evidence for a functional link between placental protooncogenes and trophoblast malignancy is reviewed. Finally, placental development, structure, and life span are discussed within an evolutionary context. The hypothesis that one or more ancient trophoblastic ERVs could have played a role in the evolution and divergence of all placental mammals is evaluated.

Genes in the pX region of human T cell leukemia virus I influence Vav phosphorylation in T cells

Human T cell leukemia virus I (HTLV-I) causes acute leukemic disease in a low percentage of infected individuals through obscure mechanisms. Our studies compare two rabbit HTLV-I-infected T cell lines: one, RH/K34, causes lethal experimental leukemia and the other, RH/K30, mediates asymptomatic infection. We show herein that the product of the protooncogene vav is constitutively Tyr-phosphorylated in RH/K34 but not in RH/K30. A role for the retrovirus in phosphorylation of Vav was assigned by transfection experiments with molecular clones of HTLV-I derived from the two lines. The HTLV-I molecular clone from RH/K30, but not that from RH/K34, down-regulates Vav phosphorylation in a Herpesvirus ateles-transformed T cell line. Use of recombinant virus clones revealed that a pX region sequence differing by two nucleotides between the two clones mediates this down-regulation. Because Vav is involved in T cell signaling and Vav phosphorylation occurs upon activation of T cells, control of the activation state of Vav by viral proteins may relate to the leukemogenic potential of certain HTLV-I-infected cells.

Expression of the vav oncogene in somatic cell hybrids

The vav oncogene is expressed primarily in tissues of hematopoietic origin. While much effort has been focused on determining the role of vav in various signal transduction pathways, little is known about the mechanism by which vav is regulated in a tissue-selective manner. This issue was examined by developing somatic cell hybrids between human U937 cells, which express vav, and mouse Balb/c 3T3 cells, which do not. If vav is primarily regulated by the presence of positive acting transcription factors, then vav expression should be maintained in hybrid cells. In contrast, if the regulation of vav is primarily negative in nature, then vav expression should be extinguished in most of the somatic cell hybrids. Of the hybrid cells that were obtained, 64% were positive by reverse transcriptase-polymerase chain reaction for the expression of the vav oncogene. Differences in the pattern of restriction enzyme cleavage sites between the mouse and human PCR products were used to determine that 6 of 11 of the positive clones expressed the normally dormant mouse gene. The other positive clones were found to express the human vav gene. In all cases, the hybrid cells preferentially retained the chromosomes and the cellular morphological appearance of the mouse Balb/c 3T3 fusion partner, which does not express the vav oncogene. Since vav is able to be transiently expressed by hybrid cells with a predominately mouse phenotype, these results support the hypothesis that vav is regulated primarily by the presence of transactivating factors which stimulate transcription, rather than by a gene silencing mechanism.