Definition of T-cell specific DNA-binding factors that interact with a 3'-silencer in the CD4+ T-cell gene Rpt-1

Analysis of the region 3' to the CD4+ T-cell gene Rpt-1 (encoding regulatory protein T-lymphocyte 1) led to the definition of a silencer element that inhibits heterologous gene expression in certain CD4+ T-cell lines but not in B-cell or non-lymphoid cell lines. Functional silencer activity in vivo was associated with the presence of a specific silencer-DNA-protein complex in electrophoretic mobility shift assays with T-cell extracts. Formation of this complex was selectively inhibited by the region in HIV-1 containing a silencer element. We discuss the possibility that DNA-binding factors may coregulate HIV-1 and Rpt-1 gene expression through a common transcriptional silencer element.