Feb 14, 2006

Activating transcription factor 3, a stress-inducible gene, suppresses Ras-stimulated tumorigenesis

The Journal of Biological Chemistry
Dan LuT Hai


ATF3 is a stress-inducible gene that encodes a member of the ATF/CREB family of transcription factors. Current literature indicates that ATF3 affects cell death and cell cycle progression. However, controversies exist, because it has been demonstrated to be a negative or positive regulator of these processes. We sought to study the roles of ATF3 in both cell death and cell cycle regulation in the same cell type using mouse fibroblasts. We show that ATF3 promotes apoptosis and cell cycle arrest. Fibroblasts deficient in ATF3 (ATF3(-/-)) were partially protected from UV-induced apoptosis, and fibroblasts ectopically expressing ATF3(-/-) under the tet-off system exhibited features characteristic of apoptosis upon ATF3 induction. Furthermore, ATF3(-/-) fibroblasts transitioned from G(2) to S phase more efficiently than the ATF3(+/+) fibroblasts, suggesting a growth arrest role of ATF3. Consistent with the growth arrest and pro-apoptotic roles of ATF3, ATF3(-) fibroblasts upon Ras transformation exhibited higher growth rate, produced more colonies in soft agar, and formed larger tumor upon xenograft injection than the ATF3(+/+) counterparts. ATF3(-/-) cells, either with or without Ras transformation, had increased Rb phosphorylation...Continue Reading

Mentioned in this Paper

Cell Cycle Progression
ATF3 gene
Cyclic AMP-Responsive DNA-Binding Protein
Gene Expression Regulation, Neoplastic
Immunoblotting, Reverse
Specimen Type - Fibroblasts
Apoptosis, Intrinsic Pathway
S Phase
Transcription, Genetic

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