Identification of a functional nuclear localization signal mediating nuclear import of the zinc finger transcription factor ZNF24

PLoS One. 2013 Nov 1;8(11):e79910. doi: 10.1371/journal.pone.0079910. eCollection 2013.

Abstract

ZNF24 is a member of the SCAN domain family of Krüppel-like zinc finger (ZF) transcription factors, which plays a critical role in cell proliferation and differentiation. However, how ZNF24 enters the nucleus in order to exert its function remains unclear since its nuclear localization signal(s) (NLS) has not been identified. Here, we generated a series of GFP-tagged deletion and point mutants and assessed their subcellular localization. Our results delimit the NLS to ZF1-2. Deletion of ZF1-2 caused cytoplasmic accumulation of ZNF24. Fusion of the ZF1-2 to green fluorescent protein (GFP) targeted GFP to the nucleus, demonstrating that the ZF1-2 is both necessary and sufficient for nuclear localization. ZNF24 containing histidine to leucine mutations that disrupt the structure of ZF1 or/and ZF2 retains appropriate nuclear localization, indicating that neither the tertiary structure of the zinc fingers nor specific DNA binding are necessary for nuclear localization. K286A and R290A mutation led to partial cytoplasmic accumulation. Co-immunoprecipitation demonstrated that ZNF24 interacted with importin-β and this interaction required the ZF motifs. The β-Catenin (CTNNB1) luciferase assays showed that the ZNF24 mutants defective in nuclear localization could not promote CTNNB1 promoter activation as the wild-type ZNF24 did. Taken together, these results suggest that consecutive ZF1-2 is critical for the regulation of ZNF24 nuclear localization and its transactivation function.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Blotting, Western
  • Cell Line
  • Cell Nucleus / metabolism*
  • HeLa Cells
  • Humans
  • Immunoprecipitation
  • Kruppel-Like Transcription Factors / genetics
  • Kruppel-Like Transcription Factors / metabolism*
  • Promoter Regions, Genetic / genetics
  • Protein Binding
  • Protein Transport / genetics
  • Protein Transport / physiology
  • Transcription Factors / genetics
  • Transcription Factors / metabolism
  • beta Karyopherins / genetics
  • beta Karyopherins / metabolism

Substances

  • Kruppel-Like Transcription Factors
  • Transcription Factors
  • ZNF24 protein, human
  • beta Karyopherins

Grants and funding

This work was supported by grants from the National Natural Science Foundation of China (No. 30871353 and No.30901322). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.