Characterization of the 5′-Flanking Region of the Human Preprogalanin Gene

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Abstract
Expression of the human galanin gene was analysed using a 3.5-kb DNA fragment comprising the 5′-flanking sequence of the gene. This sequence contains a TATA box (ATATATA) preceded by numerous potential binding sites for transcription factors such as SP1, AP2, and NFκB. Three half-palindromic estrogen response elements (EREs, GGTCA) are also found at positions −1,162, −361, and −122 bp relative to the transcription start site. To localize functionally important portions of the promoter region, several shorter fragments of the galanin 5′-flanking region were placed upstream from the chloramphenicol acetyltransferase (CAT) reporter gene. In transient transfection assays, all constructs demonstrated substantial transcriptional activity in both rat glioma/mouse neuroblastoma hybrid cells (NG108-15) and Chinese hamster ovary (CHO-K1) cells. Comparison of the basal expression levels of the different constructs suggests the presence of a negative modulator between positions −1,891 and −207. When cotransfected into NG108-15 cells with the human estrogen receptor cDNA, estrogen did not induce transcription of the human galanin gene at physiological levels of estrogen receptor, although transcription was induced up to 30-fold in the presence of high levels of receptor.