Rabbit Anti-Human ZFP42 (C-terminal) Polyclonal antibody

Rex1 (zfp42) was identified by our laboratory because of its reduced expression in F9 teratocarcinoma stem cells after retinoic acid (RA) treatment. The Rex1 (Zfp42) gene is currently widely used as a marker of embryonic stem cells. We compared the transcriptional regulation of the human Rex1 gene in NTera-2 (NT-2) human teratocarcinoma, normal human prostate epithelial cells (PrEC), and prostate cancer cells (PC-3) by promoter/luciferase analyses. Oct4, Sox2, Nanog, and Dax1 transcripts are expressed at higher levels in NT-2 and PrEC cells than in PC-3 cells. Co-transfection analyses showed that YY1 and Rex1 are positive regulators of hRex1 transcription in NT-2 and PrEC cells, whereas Nanog is not. Serial deletion constructs of the hRex1 promoter were created and analyzed, by which we identified a potential negative regulatory site that is located between -1 and -0.4 kb of the hRex1 promoter. We also delineated regions of the hRex1 promoter between -0.4 kb and the TSS that, when mutated, reduced transcriptional activation; these are putative Rex1 binding sites. Mutation of a putative Rex1 binding site in electrophoretic mobility shift assays (EMSA) resulted in reduced protein binding. Taken together, our results indicate that hRex1 binds to the hRex1 promoter region at 298 bp and positively regulates hRex1 transcription, but that this regulation is lost in PC-3 human prostate cancer cells. This lack of positive transcriptional regulation by the hRex1 protein may be responsible for the lack of Rex1 expression in PC-3 prostate cancer cells. J. Cell. Physiol. 224: 17-27, 2010. (C) 2010 Wiley-Liss, Inc.

Zfp42/Rex1 (reduced expression gene 1) is a well-known stem-cell marker that has been duplicated from YY1 in the eutherian lineage. In the current study, we characterized the in vivo roles of Rex1 using a mutant mouse line disrupting its transcription. In contrast to the ubiquitous expression of YY1, Rex1 is expressed only during spermatogenesis and early embryogenesis and also in a very limited area of the placenta. Yet, the gene dosage of Rex1 is very critical for the survival of the late-stage embryos and neonates. This delayed phenotypic consequence suggests potential roles for Rex1 in establishing and maintaining unknown epigenetic modifications. Consistently, Rex1-null blastocysts display hypermethylation in the differentially methylated regions (DMRs) of Peg3 and Gnas imprinted domains, which are known to contain YY1 binding sites. Further analyses confirmed in vivo binding of Rex1 only to the unmethylated allele of these two regions. Thus, Rex1 may function as a protector for these DMRs against DNA methylation. Overall, the functional connection of Rex1 to genomic imprinting represents another case where newly made genes have co-evolved with lineage-specific phenomena.