TY - JOUR AU - 이영식 DA - 2006/03 PY - 2006 UR - https://www.embopress.org/doi/full/10.1038/sj.emboj.7600987 UR - https://repository.hanyang.ac.kr/handle/20.500.11754/107787 AB - The transcription factor Egr-1 functions as a key regulator in cellular growth, differentiation, and apoptosis. The loss of Egr-1 expression is closely associated with tumor development, although the molecular mechanism behind the suppression of Egr-1 is largely unknown. In this report, we show that growth factor-induced transcriptional activation of Egr-1 gene is downregulated by chronic expression of oncogenic H-Ras in NIH3T3 fibroblasts. Our results demonstrate that phosphoinositide 3-kinase (PI3K) signaling is necessary for oncogenic H-Ras-mediated reduction of Egr-1 gene expression. Aberrant activation of PI3K signaling by oncogenic Ras decreased the level of serum response factor (SRF) protein through the acceleration of proteolysis, which resulted in decreased SRF binding to the serum response element (SRE) sites within the Egr-1 promoter, leading to the suppression of Egr-1 transcription. Inhibition of PI3K signaling restored the downregulation of SRF and Egr-1 expression caused by oncogenic Ras. Our findings suggest a novel signaling mechanism by which prolonged activation of oncogenic H-Ras can trigger the loss of tumor suppressor Egr-1 through the PI3K pathway in NIH3T3 fibroblast model cell lines. PB - OXFORD UNIV PRESS KW - Egr-1 KW - oncogenic H-Ras KW - phosphoinositide 3-kinase KW - serum response element KW - serum response factor TI - Suppression of Egr-1 transcription through targeting of the serum response factor by oncogenic H-Ras DO - 10.1038/sj.emboj.7600987 T2 - EMBO JOURNAL ER -