摘要：SummaryMost tumor cells reactivate telomerase to ensure unlimited proliferation, whereas the expression of human telomerase reverse transcriptase (hTERT) is tightly regulated and rate-limiting for telomerase activity maintenance. Several general transcription factors (TFs) have been found in regulatinghTERTtranscription; however, a systematic study is lacking. Here we performed an inducible CRISPR/Cas9 KO screen using anhTERTcore promoter-driven reporter. We identified numerous positive regulators including an E3 ligase DTX2. In telomerase-positive cancer cells, DTX2 depletion downregulatedhTERTtranscription and telomerase activity, contributing to progressive telomere shortening, growth arrest, and increased apoptosis. Utilizing BioID, we characterized multiple TFs as DTX2 proximal proteins, among which NFIC functioned corporately with DTX2 in promotinghTERTtranscription. Further analysis demonstrated that DTX2 mediated K63-linked ubiquitination of NFIC, which facilitated NFIC binding to thehTERTpromoter and enhancedhTERTexpression. These findings highlight a newhTERTregulatory pathway that may be exploited for potential cancer therapeutics.Graphical abstractDisplay OmittedHighlights•An inducible CRISPR/Cas9 screen identifies regulators forhTERTtranscription•DTX2 deficiency leads to telomere shortening and cell growth arrest•DTX2 mediates ubiquitination on NFIC, stabilizing NFIC binding onhTERTpromoter•DTX2-NFIC functions corporately to promotehTERTtranscription and tumorigenesisBiological sciences; Human Physiology; Molecular biology; Cancer
