Activation of the human asparagine synthetase gene by the amino acid response and the endoplasmic reticulum stress response pathways occurs by commongenomic elements

The human asparagine synthetase (AS) gene is transcriptionally regulated by amino acid deprivation (amino acid response, AAR) and the endoplasmic reti culum stress response (ERSR), also known as the unfolded protein response p athway. The results reported here document the novel observation that induc tion of the AS gene by the AAR and ERSR pathways occurs via the same set of genomic elements. Data supporting this conclusion include transient transf ection of AS promoter/reporter gene constructs that illustrate that the tra nscriptional control elements used by both pathways are contained with nucl eotides -111 to -34 of the AS pro meter. In vivo footprinting analysis of t his region identified six specific protein-binding sites. Within two of the se sites, altered footprinting was observed following amino acid or glucose deprivation, but the patterns were identical for both the AAR and the ERSR pathway. Site-directed mutation of individual nucleotides within these two binding sites confirmed their importance for regulated transcription, and none of the mutations resulted in loss of response of only one pathway, Nei ther of these two sites corresponds to a recently identified ERSR cis-eleme nt, nor do they contain consensus sequences for known transcription factors , Collectively, the data document that there are at least two independent t ranscriptional mechanisms for gene activation by the ERSR pathway, one of w hich terminates at the same genomic elements used by the AAR pathway.