Functional Significance of the C-Terminal Domain of Human Interferon Regulatory Factor-1 (IRF-1) in Gene Expression and Cell Cycle Regulation

Interferon regulatory factor-1 (IRF-1) is a transcription factor in humans that plays a crucial role in creating an antiviral state in infected cells and regulating cell cycle progression. Human IRF-1 is a modular protein with different functional domains. To investigate its functionality, we generated a truncated mutant version of human IRF-1, containing amino acids 1 to 233, compared to the wild-type IRF-1 with 325 amino acids (aa). We employed semi-nested PCR and techniques of cloning genes in both E. coli and mammalian expression vectors to produce the recombinant truncated Glutathione S-transferases tagged IRF-1 protein of molecular weight approximately 52 kDa. 12.5% SDS-PAGE was used to verify the expression of the protein. We introduced the truncated and wild-type IRF-1 into Human Embryonic Kidney cell lines HEK293 and HEK293T and detected the recombinant proteins using immunoblotting. Interestingly, the truncated IRF-1 ( increment IRF-1) version had no impact on the chromosomal genes including Bax, Bcl-2, and Cyclin D1. Furthermore, the MTT experiment showed that HEK293 and HEK293T cells were unaffected by the mutant IRF-1 in terms of proliferation and division. These results emphasize the importance of human IRF-1's amino acids 234-325 for the expression of the Bax, Bcl-2, and Cyclin D1 genes in this experimental paradigm. Consequently, this research offers significant information regarding the role of the human IRF-1 C-terminal domain.