Objective:To construct luciferase reporter plasmids of full-length and truncated promotors of rat Caspase 8 gene and detect their activity in HEK293 cells in response to interferon regulatory factor-1(IRF-1) overexpression,screening the possible binding sites for IRF-1. Methods:Rat Caspase 8 promoter(-1136~+101 nt) was amplified by PCR and cloned into the luciferase reporter plasmid(pGL3-basic). The recombinant plasmid(pGL3-Caspase 8-FL) and rat interferon regulatory factor-1(IRF-1) expression plasmid(pcDNA3.1-IRF-1) were co-transfected into HEK-293 cells and then the luciferase activity was detected to determine the role of IRF-1 in Caspase 8 gene transcription. Meanwhile,the potential IRF-1 binding sites within Caspase 8 promoter were predicted by bioinformatics software. Based on the predicted results,different luciferase reporter plasmids of truncated Caspase 8 gene promotor that named pGL3-Caspase 8-1~4 were constructed. The promoter luciferase reporter plasmids of pGL3-Caspase 8-FL or pGL3-Caspase 8-1~4 and the plasmid of pcDNA3.1-IRF-1 were co-transfected into HEK293 cells. Then,the luciferase activity was detected to screen the IRF-1 binding sites. Results:It was verified that different kinds of plasmids were all constructed correctly by PCR analysis and nucleotide sequencing. The plasmids of pGL3-Caspase 8-FL and pcDNA3.1-IRF-1 were also co-transfected into HEK293 cells,and then the luciferase activity was detected. The results showed that the transcriptional activity of Caspase 8 gene was increased markedly in response to IRF-1 overexpression. In addition,the plasmids of pGL3-Caspase 8-FL or pGL3-Caspase 8-1~4 and pcDNA3.1-IRF-1 were co-transfected into HEK293 cells,and then the luciferase activity in different groups was determined. The result displayed that the activity of pGL3-Caspase 8-4 was much lower than that in pGL3-Caspase 8-2 and pGL3-Caspase 8-3,indicating that the region of rat Caspase 8 promoter (-336~ -136 nt) might contain IRF-1 binding element. Conclusion:The rat full-length and truncated rat Caspase 8 promotor luciferase reporter plasmids were constructed successfully,and the IRF-1 binding region was identified.