Transcriptional Activation of TINF2, a Gene Encoding the Telomere-Associated Protein TIN2, by Sp1 and NF-κB Factors

• Type of Material: Article
• Authors: Zhong-Tao Xin, Emory University; Kathryn A. Carroll, Emory University; Naveen Kumar, Emory University; Kui Song, Emory University; Hinh Ly, Emory University
• Language: English
• Date: 2011-06-23
• Publisher: Public Library of Science
• Publication Version: Final Published Version
• Copyright Statement: © 2011 Xin et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
• License: Creative Commons Attribution 2.5 Generic
• Final Published Version (URL): http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0021333
• Title of Journal or Parent Work: PLoS ONE
• ISSN: 1932-6203
• Volume: 6
• Issue: 6
• Start Page: 1
• End Page: 11
• Grant/Funding Information: K.A.C was supported in part by the NIH pre-doctoral training grant (T32 GM008490). This work was funded in part by a research scholar grant from the American Cancer Society (RSG-06-162-01-GMC) and seed grants from the Emory Winship Cancer Institute (NCI-P30CA138292) and the Atlanta Clinical and Translational Science Institute and Emory University Research Committee (ACTSI-URC) (UL1RR025008) to H.L.
• Research Categories: Biology, Genetics; Health Sciences, Pathology

Abstract

The expression of the telomere-associated protein TIN2 has been shown to be essential for early embryonic development in mice and for development of a variety of human malignancies. Recently, germ-line mutations in TINF2, which encodes for the TIN2 protein, have been identified in a number of patients with bone-marrow failure syndromes. Yet, the molecular mechanisms that regulate TINF2 expression are largely unknown. To elucidate the mechanisms involved in human TINF2 regulation, we cloned a 2.7 kb genomic DNA fragment containing the putative promoter region and, through deletion analysis, identified a 406 bp region that functions as a minimal promoter. This promoter proximal region is predicted to contain several putative Sp1 and NF-κB binding sites based on bioinformatic analysis. Direct binding of the Sp1 and NF-κB transcription factors to the TIN2 promoter sequence was demonstrated by electrophoretic mobility shift assay (EMSA) and/or chromatin immunoprecipitation (ChIP) assays. Transfection of a plasmid carrying the Sp1 transcription factor into Sp-deficient SL2 cells strongly activated TIN2 promoter-driven luciferase reporter expression. Similarly, the NF-κB molecules p50 and p65 were found to strongly activate luciferase expression in NF-κB knockout MEFs. Mutating the predicted transcription factor binding sites effectively reduced TIN2 promoter activity. Various known chemical inhibitors of Sp1 and NF-κB could also strongly inhibit TIN2 transcriptional activity. Collectively, our results demonstrate the important roles that Sp1 and NF-κB play in regulating the expression of the human telomere-binding protein TIN2, which can shed important light on its possible role in causing various forms of human diseases and cancers.