An improved growth hormone reporter gene shows a different pattern of transactivation by promoter fragments

Granulocytic differentiation of myeloid NB4 cells was noted to transactivate the genomic human growth hormone (hGH) reporter construct in the absence of a driving test promoter. Such spurious hGH transactivation also occurred upon co-transfection of plasmids expressing the transactivators c-Myb and C/EBPalpha into undifferentiated NB4 cells. Modifications to the reporter gene and the vector resulted in a reporter construct unaffected by such stimuli. When human neutrophil peptide 1 (hnp-1) gene promoter fragments were tested using both the original and modified reporter constructs, a clear difference in the pattern of transactivation was noted. This suggests that promoter and enhancer elements in the reporter construct plasmid DNA can effect the analysis of the test promoter.