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Identification of a p53-dependent negative response element in the Bcl-2 gene

La Jolla Cancer Research Foundation, Cancer Research Center, California 92037.
Cancer Research (Impact Factor: 9.28). 07/1994; 54(12):3131-5.
Source: PubMed

ABSTRACT Recently, we have shown that the p53 tumor suppressor gene product can inhibit expression of the bcl-2 gene. In this report, we explored the molecular basis for p53-mediated down-regulation of bcl-2 gene expression using a cotransfection approach involving p53 expression plasmids and chloramphenicol acetyltransferase (CAT) reporter gene constructs containing regions from the bcl-2 gene. When transfected into a p53-deficient human lung cancer cell line H358, reporter gene constructs containing only the promoter region of bcl-2 and upstream sequences were not suppressed by p53. Inclusion of bcl-2 gene sequences corresponding to the 5' untranslated region in bcl-2/CAT constructs, however, resulted in p53-dependent down-regulation. A 195-base pair segment from the bcl-2 gene 5' untranslated region was found to be capable of conferring p53-dependent repression on a heterologous expression plasmid containing CAT under the control of an SV40 immediate early-region promoter. This p53-negative response element functioned in an orientation-independent manner when placed either upstream or downstream of the SV40-CAT transcription unit. The results demonstrate the existence of a negative response element in the bcl-2 gene through which p53 may either directly or indirectly transcriptionally down-regulate expression of this gene involved in the regulation of programmed cell death.

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    • "These results suggest that the anterior hindbrain truncation in gbx2 morphants may arise from a combination of decreased proliferation and increased cell death. It has been shown that non-specific cell death caused by morpholinos can be due to an upregulation of p53, which modulates a variety of pro-apoptotic genes (Miyashita et al., 1994; Roperch et al., 1998; Robu et al., 2007). To test whether the cell death in r2, r3, and r5 is specific to gbx2 knockdown, we co-injected embryos with p53-MO to minimize non-specific apoptosis. "
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    • "In contrast, Bcl-2 is one of the key genes known to downregulate BAX and certain tumour suppressor proteins , and therefore has the potency to inhibit the intrinsic mitochondrial pathway of apoptosis (Hockenbery 1992; Miyashita et al. 1994). Previous studies have demonstrated that a decreased expression of Bcl-2 is associated with LEC apoptosis and Fig. 5. Bcl-2 mRNA expression of untreated Lens epithelial cells after illumination with plain white light (black columns) and after preincubation with coQ10 (grey columns), as investigated by quantitative RT-PCR. "
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