We recently discovered an opposing initiator promoter (Inr) downstream of the sense promoter region of the eIF-2α gene (Silverman, T., Noguchi, M., and Safer, B. (1992) J. Biol. Chem. 267, 9738-9742). By reverse transcriptase/polymerase chain reaction analysis of G0 and activated (G1) T-lymphocyte RNAs, overlapping sense and antisense transcripts are now identified. Sense transcription of the eIF-2α gene proceeds from left to right to generate α-mRNA; antisense transcription proceeds from right to left to generate RNA, having a sequence complementary to eIF-2α mRNA. Upstream indicates a position 5' relative to the transcription start site. Using DNase I footprint analysis and EMSA, we have found a potential cis- regulatory sequence immediately upstream of the Inr which binds a 43-kDa protein. In addition to conferring protection against DNase I (+457 to +474), the factor also generates hypersensitive sites directly over the Inr (+447 to +457). Insertion of the Inr footprint region into a luciferase reporter gene construct increases expression 150-fold. While mutation of the Inr conserved sequence decreases luciferase activity by 50%, mutation of the 43-kDa factor binding site inhibits luciferase activity by 20%. Sense orientation of the Inr footprint region decreases activity by 80%. The 43-kDa Inr-associated binding protein may be involved in allowing access of RNA polymerase II transcription complexes to the initiation site of this TATA-less gene. A model for the regulation of eIF-2α expression involving the rapid degradation of dsRNA generated by the relative activities of the two overlapping and opposing promoters is proposed.
|Original language||English (US)|
|Number of pages||7|
|Journal||Journal of Biological Chemistry|
|State||Published - Nov 18 1994|
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