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Cell Death Differ. 2006 Sep;13(9):1495-505. Epub 2005 Dec 9.

Notch1 confers thymocytes a resistance to GC-induced apoptosis through Deltex1 by blocking the recruitment of p300 to the SRG3 promoter.

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  • 1Department of Biological Sciences, Institute of Molecular Biology of Genetics, and Center for Functional Cellulomics, Seoul National University, Seoul 151-742, Korea.


One notable phenotypic change during the differentiation of immature thymocytes into either mature CD4 or CD8 single-positive lineages is the acquisition of a resistance to glucocorticoid (GC)-induced apoptosis. We have previously reported that SRG3 is critical in determining the sensitivity for the GC-induced apoptosis in developing thymocytes. We report here that Notch signaling downregulates the transcriptional activation of SRG3 through N-box and/or E-box elements on its promoter. RBP-J represses SRG3 transcription through the N-box motif. On the other hand, Deltex1 competitively inhibits the binding of p300 to E2A/HEB protein bound to the E-box elements and represses the SRG3 promoter activity. Moreover, enforced expression of Deltex1 restored double-positive (DP) thymocyte survival from the GC-induced apoptosis. Our results suggest that Notch signaling confers differentiating DP thymocytes resistance to GCs by regulating the SRG3 expression through Deltex1, and that Deltex1 and SRG3 may play a significant role during DP thymocyte maturation.

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