Previous studies have shown that transcription of the gene encoding bovine
calpastatin, an inhibitor of the calcium-activated cysteine protease calpai
n, is upregulated following activation of cAMP-dependent signaling pathways
. In this study, deletion and site-directed mutagenesis experiments were pe
rformed to identify cis elements conferring cAMP responsiveness. Heterologo
us promoter assays demonstrated that all cAMP-responsive cis elements were
located within -102 nucleotides (nt) of transcription initiation. Deletion
of an element (GTCA) at nt +13 that is identical to half of the palindromic
cAMP-responsive element (TGACGTCA) identified in other cAMP-responsive gen
e promoters had no effect on the response of the calpastatin promoter to di
butyryl-cAMP, although a 67% reduction in basal promoter activity was obser
ved. In contrast, two point mutations in a cis element at nt -76 (GTCA to a
TCt) abolished cAMP responsiveness. These results demonstrate that the calp
astatin promoter sequence between nt -1653 and +130 contains a single cAMP-
responsive element (GTCA) located at nt -76, and suggest a direct molecular
pathway by which activation of cAMP signaling could lead to increased calp
astatin gene transcription and reduction in calpain-mediated proteolysis. (
C) 1998 Elsevier Science B.V. All rights reserved.