EXPRESSION AND TRANSCRIPTIONAL REGULATION OF THE HUMAN ALPHA-3 NEURONAL NICOTINIC RECEPTOR SUBUNIT IN T-LYMPHOCYTE CELL-LINES

The expression of neurotransmitter receptors on the surface of immunoc ompetent cells is generally accepted as evidence that the nervous syst em can influence immune responses, even though many aspects of these i nteractions remain to be elucidated. In this article, we analyzed the expression of the alpha 3 nicotinic receptor subunit in human cell lin es of myeloid and lymphoid origin and show that the alpha 3 mRNA and t he receptor mo:ecules containing this subunit are specifically express ed in T lymphocyte cell lines. We have previously characterized the st ructural properties of the human alpha 3 nicotinic subunit gene promot er and defined its functional profile in neuronal cells; in this study , we analyzed the activity of the alpha 3 promoter in T lymphocytes an d found that the same minimal promoter located in the 0.16-kb Bg/II-Ac cIII fragment is responsible for the expression of the alpha 3 mRNA in both neuronal and T lymphocyte cell lines. However, the alpha 3 trans cription initiation patterns in the two cell types were both qualitati vely and quantitatively different, and the minimal promoter was differ entially modulated by downstream and upstream regulatory elements. The se findings suggest that distinct transcriptional mechanisms allow the same promoter to be regulated in a tissue-specific fashion, according to the different functional needs of the two cell types.