Zinc-finger structure, in which a Zn2+ ion binds to four cysteines or histidines in a tetrahedral structure, is a very common motif of nucleic acid-binding proteins. The corresponding interaction model is present in 3% of the genes in the human genome. As a result, the zinc finger has been extremely useful in various therapeutic and research capacities and in biotechnology. In a stable configuration of the zinc finger, the cysteine amino acids are deprotonated and become negatively charged. Thus, the Zn2+ ion is overscreened by four cysteine charges (overcharged). Whether this overcharged configuration is also stable when such a negatively charged zinc finger binds to a negatively charged DNA molecule is unknown. We investigated how the deprotonated state of cysteine influences its structure, dynamics, and function in binding to DNA molecules by using an all-atom molecular dynamics simulation up to the microsecond range of an androgen receptor protein dimer. Our results showed that the deprotonated state of cysteine residues is essential for the mechanical stabilization of the functional, folded conformation. This state stabilizes not only the protein structure but also the protein–DNA binding complex. The differences in the structural and energetic properties of the two sequence-identical monomers are also investigated and show the strong influence of DNA on the structure of the zinc-finger protein dimer upon complexation. Our result can potentially lead to a better molecular understanding of one of the most common classes of zinc fingers.

The pro-oncogenic function of TR3, an orphan nuclear receptor, has been reported in prostate cancer. However, the roles of TR3 in androgen receptor (AR) expression and signaling in prostate cancer cells are poorly understood. Database analysis revealed that TR3 expression level is elevated in prostate tumors, and is positively, although weakly, correlated with that of AR. TR3 overexpression increased the production of AR splice variants in addition to general upregulation of AR expression. TR3 interacted with some spliceosomal complex components and AR precursor mRNA, altering the splice junction rates between exons. TR3 also enhanced androgen-independent AR function. Furthermore, TR3 overexpression increased cell proliferation and mobility of AR-positive prostate cancer cells and stimulated tumorigenesis of androgen-independent prostate cancer cells in mouse xenograft models. This is the first study to report that TR3 is a multifunctional regulator of AR signaling in prostate cancer cells. TR3 alters AR expression, splicing process, and activity in prostate cancer cells, increasing the androgen independence of AR signaling. Therefore, TR3 may play a crucial role in the progression of prostate cancer to an advanced castration-resistant form.

JAG1 expression is upregulated in high-grade metastatic prostate carcinomas and associated with poor disease-free survival of patients with prostate cancer. Intriguingly, all JAG1-positive prostate carcinomas express JICD although JICD function in prostate cancer (PC) cells is poorly understood. In this study, we found that JICD overexpression increased the expression levels of AR, especially AR-Vs, in PC cell lines and significantly enhanced androgen-independent and androgen-dependent function of ARs. Interestingly, JICD overexpression upregulated the expression of the PCSC marker CD133 in PC cells as the expression of self-renewal markers; namely, NANOG and OCT3/4 increased. In addition, JICD overexpression highly increased the expression of anti-apoptotic BCL-XL protein, while it little affected the expression of apoptotic BIM protein. In 3D cell culture assays, the spheres formed by JICD-overexpressing PC subline cells (C4-2 and CWR22Rv1) were larger than those formed by control (EV) subline cells with undifferentiated morphology. Although JICD overexpression caused quiescence in cell proliferation, it activated the expression of components in PCSC-related signaling pathways, increased PC cell mobility, and promoted in vivo xenograft mouse tumorigenesis. Therefore, JICD may play a crucial role in enhancing androgen independence and promoting stem-like properties in PC cells and should be considered a novel target for CRPC and PCSC diagnostic therapy.

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