CHOP gene expression in response to endoplasmic-reticular stress requires NFY interaction with different domains of a conserved DNA-binding element

The transcription factor CHOP/GADD153 gene is induced by cellular stress an d is involved in mediating apoptosis. We report the identification of a con served region in the promoter of the CHOP gene responsible for its inducibi lity by endoplasmic reticulum (ER) stress, Deletion mutants of the human CH OP promoter Identify a region comprising nucleotides -75 to -104 required f or both constitutive and ER-stress-inducible expression. This region of the promoter, the ER-stress element (ERSE) is sufficient to confer both increa sed basal activity and PH-stress inducibility to an otherwise inactive hete rologous promoter. The CHOP ERSE is a novel Variant of the ERSE as it conta ins two different functional domains, and a GA- instead of CC-rich interven ing sequence, The CCAAT-box domain occupied by the constitutive transcripti onal activator nuclear factor Y (NFY) is required for constitutive activati on whereas the variant GCACG 'inducible' domain uniquely mediates ER-stress inducibility. By UV-crosslinking analysis NFY makes contact not only with the constitutive activator CCAAT box but also with the inducible GCACG doma in. Deletions and nucleotide substitutions in the CCAAT box as well as its replacement by an SP1 site failed to support ER inducibility, These finding s support the notion that NFY is not only required for constitutive activat ion of CHOP gene transcription, but is also an active and essential element for the assembly of an ER-stress-inducible enhanceosome that activates CHO P gene expression in response to cellular stress.