Abstract
Recent data suggest that the transcription factor Zfp148 represses activation of the tumor suppressor p53 in mice and that therapeutic targeting of the human orthologue ZNF148 could activate the p53 pathway without causing detrimental side effects. We have previously shown that Zfp148 deficiency promotes p53-dependent proliferation arrest of mouse embryonic fibroblasts (MEFs), but the underlying mechanism is not clear. Here, we showed that Zfp148 deficiency downregulated cell cycle genes in MEFs in a p53-dependent manner. Proliferation arrest of Zfp148-deficient cells required increased expression of ARF, a potent activator of the p53 pathway. Chromatin immunoprecipitation showed that Zfp148 bound to the ARF promoter, suggesting that Zfp148 represses ARF transcription. However, Zfp148 preferentially bound to promoters of other transcription factors, indicating that deletion of Zfp148 may have pleiotropic effects that activate ARF and p53 indirectly. In line with this, we found no evidence of genetic interaction between TP53 and ZNF148 in CRISPR and siRNA screen data from hundreds of human cancer cell lines. We conclude that Zfp148 deficiency, by increasing ARF transcription, downregulates cell cycle genes and cell proliferation in a p53-dependent manner. However, the lack of genetic interaction between ZNF148 and TP53 in human cancer cells suggests that therapeutic targeting of ZNF148 may not increase p53 activity in humans.
Highlights
Recent data suggest that the transcription factor Zfp[148] represses activation of the tumor suppressor p53 in mice and that therapeutic targeting of the human orthologue ZNF148 could activate the p53 pathway without causing detrimental side effects
The analysis revealed a set of more than 300 genes that were downregulated in Zfp148gt/gt mouse embryonic fibroblasts (MEFs) compared to wild-type controls, and rescued in Zfp148gt/gt MEFs after adenoviral expression of Zfp[148] cDNA compared to empty vector (Fig. 1A and Supplementary Data S1)
Overrepresentation analysis showed strong enrichment of cell cycle-related genes (Fig. 1B). Since this category of genes is regulated by E2F transcription factors, we identified known E2F targets from earlier p ublications[17,19] and investigated their rank in the gene list
Summary
Recent data suggest that the transcription factor Zfp[148] represses activation of the tumor suppressor p53 in mice and that therapeutic targeting of the human orthologue ZNF148 could activate the p53 pathway without causing detrimental side effects. Deletion of one copy of Zfp[148] reduced proliferation of macrophages and atherosclerosis in Apoe−/− mice by increasing p53 activity[15]. These results indicate that deletion of one copy of Zfp[148] is sufficient to induce therapeutically meaningful p53 activation. We investigate mechanisms behind cell cycle arrest of Zfp148-deficient (Zfp148gt/gt) MEFs by using global gene expression analysis, targeted inactivation of Cdkn2a genes, genome-wide chromatin immunoprecipitation, and public CRISPR and siRNA screen data
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