BRCA1 activation of the GADD45 promoter
Authors: Q Zhan
H Zhao
W Fan
P Blanck
A J Fornace Jr
A B Colchagie
S Jin
F Fan
Journal: Oncogene (2000)
Discipline: MOLECULAR BIOLOGY & GENETICS
Keywords: BRCA1; gene regulation; GADD45; transactivation; promoter
Affiliations: Department of Radiation Oncology, Cancer Institute, University of Pittsburgh School of Medicine, BST W-945, 200 Lothrop Street, Pittsburgh, Pennsylvania, PA 15213, USA.

Abstract:  Breast cancer susceptibility gene BRCA1 has been implicated in the control of gene regulation and such regulated genes are thought to mediate the biological role of BRCA1. Overexpression of BRCA1 induces GADD45, a p53-regulated and stress-inducible gene. However, the molecular mechanism by which BRCA1 induces the expression GADD45 remains unclear. In this report, we have shown that the GADD45 promoter is strongly activated following expression of wild-type BRCA1. In contrast, both the tumor-derived BRCA1 mutants (p1749R and Y1853insA) and truncated BRCA1 mutant protein (Delta500 - 1863 BRCA1), which lack transactivation activity, were unable to activate the GADD45 promoter, indicating that the BRCA1-mediated activation of the GADD45 promoter requires normal transcriptional properties of BRCA1. BRCA1 did not induce the c-Jun and c-fos promoters, which rules out a general effect of BRCA1 on other immediate-responsive genes. Expression of the human papillomavirus E6 and the dominant-negative mutant p53 proteins had no effect on the induction of the GADD45 promoter by BRCA1, suggesting that activation of the GADD45 promoter by BRCA1 is independent of cellular p53 function. With the 5'-deletion analysis, the BRCA1-responsive element of the GADD45 promoter was mapped at the region from -121 to -75. Disruption of this region resulted in the abrogation of BRCA1 activation of the GADD45 promoter. Taken together, these results demonstrate that the mechanism by which BRCA1 induces GADD45 is mainly through the transactivation of the GADD45 promoter, further demonstrating the evidence that GADD45 acts as one of the BRCA1-regulated genes. Oncogene (2000) 19, 4050 - 4057. 

Retracted: No

PubPeer comments:
 CAT assay image in Figure 1A reappeared (red box). Could authors re-check the original data? See figure below. ![file] , 
 Dear Cicindela Chrysippe, Thank you for your interest of our study and pointing this mistake out. In Figure 1A, CAT assay was performed in MCF-7 and HCT116 cell lines to determine whether Gadd45 was transcriptionally regulated by BRCA1. Regrettably, we put the same picture for MCF-7 pHG45-CAT2 group and HCT116 pHG45-CAT2 group by mistake. We have checked the original data of these assays, and corrected the Figure 1A in the following figure. We have contacted with the editor office of Oncogene to make correction of this figure. Again many thanks for your comment. Corrected Figure 1A ![file] Figure 1 Activation of the GADD45 promoter following expression of BRCA1. (A) 4 u03bcg of the GADD45 promoter CAT reporter constructs (pHG45-CAT1 and pHG45-CAT2) were cotransfected with 4 u03bcg of either pCR3.BRCA1 (BRCA1) and pCMV neo expression vectors into MCF-7 and HCT116 cells via the calcium phosphate method. Forty- eight hours later, cells were collected for the CAT assay (see Materials and methods). To determine transfection efficiency, 4 u03bcg of GFP (green fluorescence protein) expression vector was co-transfected with each tested plasmid and the expression of GFP protein was detected as the internal control of transfection. ,