The Shelterin TIN2 Subunit Mediates Recruitment of Telomerase to Telomeres |
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| Authors: | Amanda K. Frank Duy C. Tran Roy W. Qu Bradley A. Stohr David J. Segal Lifeng Xu |
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| Affiliation: | 1. Department of Microbiology and Molecular Genetics, University of California, Davis, Davis, California, United States of America.; 2. Department of Pathology, University of California, San Francisco, San Francisco, California, United States of America.; 3. Genome Center and Department of Biochemistry and Molecular Medicine, University of California, Davis, Davis, California, United States of America.; Chinese Academy of Sciences, CHINA, |
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| Abstract: | Dyskeratosis Congenita (DC) is a heritable multi-system disorder caused by abnormally short telomeres. Clinically diagnosed by the mucocutaneous symptoms, DC patients are at high risk for bone marrow failure, pulmonary fibrosis, and multiple types of cancers. We have recapitulated the most common DC-causing mutation in the shelterin component TIN2 by introducing a TIN2-R282H mutation into cultured telomerase-positive human cells via a knock-in approach. The resulting heterozygous TIN2-R282H mutation does not perturb occupancy of other shelterin components on telomeres, result in activation of telomeric DNA damage signaling or exhibit other characteristics indicative of a telomere deprotection defect. Using a novel assay that monitors the frequency and extension rate of telomerase activity at individual telomeres, we show instead that telomerase elongates telomeres at a reduced frequency in TIN2-R282H heterozygous cells; this recruitment defect is further corroborated by examining the effect of this mutation on telomerase-telomere co-localization. These observations suggest a direct role for TIN2 in mediating telomere length through telomerase, separable from its role in telomere protection. |
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