Evidence for a calcium regulated, bidirectional intronic promoter in the murine TCR V{alpha}1 gene |
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Authors: | Maeda, Toshiro Devens, Bruce H. Fukuse, Satoshi Turck, Christoph Webb, David R. |
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Affiliation: | Center for Inflammation Research, Syntex Research 3401 Hillview Avenue, Palo Alto, CA 94304, USA 1 Howard Hughes Medical Institute, Department of Medicine, University of California San Francisco Medical Center San Francisco, CA 94143, USA |
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Abstract: | Previous studies of the TCR chain gene have located promoterelements 5' to the start of the various V genes. The only fullycharacterized enhancer for the entire chain gene (V, J andC genes) has been located {small tilde}3 kb from the 3' endof C . We now report the existence of additional regulatory elementslocated in the introns of several murine V genes (V 1, V 3 andV B6.2.16). In the case of V 1, this element appears to be a promoterwith bidirectional activity that is not T cell specific. Interestingly,upstream of the promoter in the antisense strand, an open readingframe has been found that codes for a small molecular weightprotein ({small tilde}60 amino acids) that contains a prollne-richregion and a tyrosine-isoleucine motif that has homology toIgß (the B29 gene product). A rabbit antiserum madeagainst this sequence has confirmed its existence by Westernblot and immunoprecipitation. Thus this V 1 intronic promoterhas the potential not only to induce the formation of a truncatedV 1 gene product, but also regulates the expression of a smallmolecular weight protein that may be involved in lymphocyteantigen receptor signaling. The activity of this promoter isregulated by changes in intracellular calcium. In the presenceof ionomycin the promoter is down-regulated in the sense directionand its activity is enhanced in the antisense direction. Thisresult suggests that this promoter can act differentially toproduce two very different gene products. The bidirectionalV 1 promoter appears to be the first in the Ig superfamily toinduce potentially functional proteins in both directions. |
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Keywords: | enhancer element, dyad symmetry, Igß , serum response element, V /math/alpha.gif" ALT=" {alpha}" BORDER=" 0" >3, V /math/alpha.gif" ALT=" {alpha}" BORDER=" 0" >B6.2.16 |
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