Nuclear trafficking of the POZ-ZF protein Znf131

Abstract

Znf131 is a member of the BTB/POZ family of transcription factors with roles in development and carcinogenesis. Like many members of this protein family, Znf131 displays robust nuclear localization in cultured cells, but the mechanism(s) of Znf131 nuclear trafficking is unknown. Here, we report the mechanism of Znf131 nuclear localization. Visual inspection of the Znf131 amino acid sequence revealed three basic regions (BR-1, -2 and -3) with the potential to serve as nuclear localization signals (NLS). Of the three basic regions, only BR-1 functioned independently to efficiently target heterologous beta-gal-GFP fusion proteins to HeLa cell nuclei. However, a Znf131 truncation mutant containing BR-2 and BR-3 efficiently targeted heterologous beta-gal-GFP fusion proteins to HeLa cell nuclei. Mutational analysis of full-length GFP-tagged Znf131 revealed that loss of any one BR alone did not prevent Znf131 nuclear localization. This apparent redundancy in NLS activity was due to the fact that intact BR-1 or BR-2 alone could target full-length Znf131 to nuclei. Consequently, simultaneous mutation of BR-1 and BR-2 abolished full-length Znf131 nuclear localization. Therefore, BR-1 and BR-2 are functional NLSs for Znf131 and as such are designated NLS-1 and NLS-2. Finally, wild type Znf131, and not a Znf131 NLS-defective mutant (NLS-1m/NLS-2m) interacted preferentially with the nuclear import receptor Importin-alpha3 in vitro.

UHRF2, a Ubiquitin E3 Ligase, Acts as a Small Ubiquitin-like Modifier E3 Ligase for Zinc Finger Protein 131

“…1C, top and middle panels). This finding is consistent with previous reports that both UHRF2 and ZNF131 are nuclear proteins (24,31). Moreover, when cells co-express UHRF2 and ZNF131, the proteins are co-localized within the nucleoplasm (Fig.…”

Small Ubiquitin-like Modifier (SUMO) Modification of Zinc Finger Protein 131 Potentiates Its Negative Effect on Estrogen Signaling

“…1C, middle panels). This confirms previous findings that ZNF131 is a nuclear protein (34), and that hPc2 is a component of polycomb nuclear bodies (19). Interestingly, when cells co-express ZNF131 and hPc2, the proteins co-localize within the polycomb bodies (Fig.…”

High-throughput cell-based screening reveals a role for ZNF131 as a repressor of ERalpha signaling

“…ZNF131 protein has been placed in the superfamily of POK (BTB/POZ and krüppel) proteins, which contain a BTB/POZ domain in their N-terminal region as well as 5 typical C2H2 zinc fingers, and an additional C2HC zinc finger structure, in their C-terminus [ 28 ]. In POK proteins, including ZNF131, the BTB/POZ domain putatively confers a specific nuclear localization pattern and mediates transcriptional repression [ 34 ]. We confirmed the nuclear localization of human ZNF131 in HeLa cells using a ZNF131-GFP expression construct (data not shown).…”