The gammac-cytokine regulated transcription factor, STAT5, increases HIV-1 production in primary CD4 T cells.

Although HIV-1 (HIV) replicates poorly in non-dividing CD4 lymphocytes, resting T cells contribute to the latent reservoir. The gammac-related cytokines reverse this block to HIV infection; however, the molecular mechanisms controlling this process are not understood. We asked whether the gammac-cytokine regulated transcription factor, signal transducer and activator of transcription 5 (STAT5), activates HIV transcription. We identified three regions in the long terminal repeat (LTR) as close matches to the STAT5 consensus-binding site and show that STAT5 binds the LTR during HIV infection. Expression of Janus kinase 3 (JAK3) or STAT5 in primary human CD4 T cells activated LTR transcription, while transactivation-incompetent dominant-negative STAT5 inhibited JAK3-induced LTR activity and infection of activated HIV-producing CD4 T-cells. In addition, overexpression of STAT5 increased virus production in unstimulated primary T cells - both the number of p24+ cells and their level of p24 production - suggesting that STAT5 promotes a permissive state for HIV infection. These data may have implications for regulation of latency and therapeutic strategies for control of HIV disease.

Chronic graft-versus-host reaction is associated with a decrease in Ig light chain receptor editing in bone marrow self-reactive B cells.

The encounter of developing B cells in the bone marrow with soluble hen egg lysozyme (sHEL) self antigen induces anergy and endogenous kappa light chain rearrangements ('receptor editing'). We have previously shown that induction of chronic graft-versus-host reaction (GVH) in tolerant Ig/sHEL mice results in prevention of B cell anergy in the bone marrow and the spleen. We now report that in chronic GVH, immature self-reactive B cells also show reduced levels of receptor editing in the bone marrow. This is evidenced by the following observations: (a) a small population of'receptor-edited' B cells, which is found in tolerant mice, is markedly reduced in mice that have lost tolerance in chronic GVH; (b) self-reactive B cells in GVH mice have reduced levels of endogenous kappa chain rearrangements; and (c) recombinase-activating gene (RAG)-2 expression is markedly decreased in immature self-reactive B cells in the bone marrow of chronic GVH mice. These results suggest that in chronic GVH newly emerging B cells escape tolerance, in part because of decreased receptor editing in the bone marrow. Thus, the autoimmunity induced by chronic GVH may ultimately result from the failure of B cell tolerance at multiple checkpoints.

Cloning and characterization of porcine ovarian estrogen receptor beta isoforms.

The cDNA for the full-length porcine estrogen receptor beta (ER beta) and an alternatively spliced transcript with a deletion of exon 5 (ER beta delta 5) was cloned from pig ovary. RNase protection assays revealed that ER beta mRNA was expressed in the preovulatory follicles and early, midluteal, and regressing corpora lutea (CL) of eCG +/- hCG-primed gilts. ER beta and ER beta delta 5 transcripts were shown by semiquantitative reverse transcription polymerase chain reaction to be expressed at a ratio of approximately 2:1 in granulosa cells, small, medium, and large antral follicles, and midluteal phase corpora lutea of unprimed animals. Immunoreactive ER beta proteins corresponding to the size of in vitro translated ER beta and ER beta delta 5 were detected by immunoblot. Full-length ER beta was detected in granulosa, small, medium, and large antral follicles, and midluteal phase CL of unprimed animals. Putative ER beta delta 5 immunoreactive bands were abundant only in granulosa cell extracts. In COS-1 cells, transfected ER beta delta 5 had no effect on basal transcription of an estrogen-responsive reporter construct but did repress wild-type ER beta transactivation when cotransfected at 10-fold excess plasmid. No repression of ER alpha transactivation was observed. In primary granulosa cell cultures, transfected ER beta delta 5 plasmid did not inhibit basal reporter activation. ER beta delta 5 was shown by immunofluorescence to localize to the nucleus in transfected COS-1 cells. In vitro translated ER beta delta 5 proteins bound estrogen response elements in DNA in electrophoretic mobility shift assays, as indicated by supershift analysis. ER beta is abundant in porcine ovary, and a naturally occurring splice variant missing exon 5 may have biological function.