Absence of the type I IFN system in EC cells: Transcriptional activator (IRF-1) and repressor (IRF-2) genes are developmentally regulated

MyD genes in negative growth control

“…Interferon regulatory factor 1 (IRF-1) in negative growth control MyD32, highly expressed in normal myeloblast enriched bone-marrow cells, was found to encode for interferon regulatory factor-1 (IRF-1), (Abdollahi et al, 1991b), a transcriptional activator of the interferonb (IFNb) gene (Fugita et al, 1989;Harada et al, 1990;Miyamoto et al, 1988). Using M1 cells, induced for terminal di erentiation by either IL6 or LIF, it was shown that IRF-1 expression is rapidly induced in the absence of de novo protein synthesis.…”

“…IRF-1, is expressed in many cell types (Fugita et al, 1989;Harada et al, 1990;Miyamoto et al, 1988;Reis et al, 1992;Yu-Lee et al, 1990), where it appears to play a role as a tumor suppresser gene, whose loss of function leads to malignant transformation. Consistent with this notion, Harada et al (1993) have shown that balanced expression of IRF-1 and IRF-2, an antagonistic repressor of IRF-1 and IFNb transcription, is critical for normal cell growth.…”

Co-occupancy of the interferon regulatory element of the class II transactivator (CIITA) Type IV promoter by interferon regulatory factors 1 and 2

“…IRF-1 and IRF-2 are generally regarded as a pair of mutually antagonizing transcription factors. IRF-1 functions as a transcriptional activator of Type I IFNs and other IFN stimulated genes (ISGs), whereas IRF-2 antagonizes IRF-1 activation by competing with IRF-1 for its DNA binding site (Harada et al, 1989(Harada et al, , 1990Tanaka et al, 1993;Taniguchi et al, 1995Taniguchi et al, , 1997. IRF-1 and IRF-2 are also implicated in cell growth control with IRF-1 displaying tumor suppressor activity (Willman et al, 1993;Kirchho et al, 1993;Harada et al, 1993Harada et al, , 1994Tanaka et al, 1996;Taniguchi et al, 1995Taniguchi et al, , 1997 and IRF-2 having oncogenic potential Taniguchi et al, 1995Taniguchi et al, , 1997.…”

Activation and repression of the 2-5A synthetase and p21 gene promoters by IRF-1 and IRF-2

“…IRF-1 and IRF-2 exhibit 62% homology in the N-terminal region which confers DNA binding speci®city but are functionally distinct factors; IRF-1 acts as a transcriptional activator, whereas IRF-2 functions as a repressor of IRF-1-activated gene expression (Miyamoto et al, 1988;Harada et al, 1989Harada et al, , 1990.…”