title: ZSCAN4 and TRF1: A functionally indirect interaction in cancer cells independent of telomerase activity.
abstract: OBJECTIVE
  Recently, the newly identified embryonic stem cell marker, Zinc finger and SCAN domain containing 4 gene (ZSCAN4), which plays a key role in genomic stability by regulating telomere elongation, was shown to co-localize with TRF1 foci. This suggests that the interaction of ZSCAN4 with TRF1 functions in regulation of telomere elongation in ESC. Based on these studies, we hypothesized that ZSCAN4 binds to TRF1 in cancer cells to function in regulating telomere length. The purpose of this study was to determine whether this interaction occurred across different cell lineage-derived cancers and whether telomerase status impacted this relationship. To that end, telomerase positive cervical cancer cells (HeLa) and breast cancer cells (MCF7), and telomerase negative osteosarcoma cells (SaOS2), were analyzed for ZSCAN4 and TRF1 interactions.
  
  
  RESULTS
  Immunocytochemistry demonstrated co-localization of ZSCAN4 and TRF1 to the nucleus. This functional relationship was confirmed using BiFC imaging analysis based on distance in situ. Co-immunoprecipitation and pull-down assay results demonstrated that ZSCAN4 binds with TRF1 in vitro indirectly. All three cell types showed similar results.
  
  
  CONCLUSIONS
  In this study, we revealed, for the first time, that ZSCAN4 indirectly interacts with TRF1 (functional association protein) in cancer cells. Furthermore, we show that ZSCAN4 plays an important role independent of telomere maintenance pathways (telomerase positive and ALT) or cell lineage.
authors.affiliation: Department of Biological Sciences, Texas Tech University, Lubbock, TX, 79409, USA. Electronic address: Kyungwoo.Lee@cchmc.org.
authors.forename: Kyungwoo
authors.initials: K
authors.lastname: Lee
authors.affiliation: Department of Biological Sciences, Texas Tech University, Lubbock, TX, 79409, USA; Texas Tech University Imaging Center, Lubbock, TX, 79409, USA. Electronic address: lauren.gollahon@ttu.edu.
authors.forename: Lauren S
authors.initials: LS
authors.lastname: Gollahon
mesh_terms: D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism*; D005260:Female; D006367:HeLa Cells; D006801:Humans; D007150:Immunohistochemistry; D061986:MCF-7 Cells; D009369:Neoplasms / Q000378:metabolism* / Q000473:pathology; D011485:Protein Binding; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D019098:Telomerase / Q000378:metabolism*; D059505:Telomere Homeostasis / Q000502:physiology; D035321:Telomeric Repeat Binding Protein 1 / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism*
chemical_list: D004268:DNA-Binding Proteins; D011993:Recombinant Fusion Proteins; D035321:Telomeric Repeat Binding Protein 1; D014157:Transcription Factors; C582979:ZSCAN4 protein, human; D019098:Telomerase
keywords: ALT pathway; Cancer; TRF1; Telomerase; Telomeres; ZSCAN4