TIN2-tethered TPP1 recruits human telomerase to telomeres in vivo.
نویسندگان
چکیده
Recruitment to telomeres is a pivotal step in the function and regulation of human telomerase; however, the molecular basis for recruitment is not known. Here, we have directly investigated the process of telomerase recruitment via fluorescence in situ hybridization (FISH) and chromatin immunoprecipitation (ChIP). We find that depletion of two components of the shelterin complex that is found at telomeres--TPP1 and the protein that tethers TPP1 to the complex, TIN2--results in a loss of telomerase recruitment. On the other hand, we find that the majority of the observed telomerase association with telomeres does not require POT1, the shelterin protein that links TPP1 to the single-stranded region of the telomere. Deletion of the oligonucleotide/oligosaccharide binding fold (OB-fold) of TPP1 disrupts telomerase recruitment. In addition, while loss of TPP1 results in the appearance of DNA damage factors at telomeres, the DNA damage response per se does not account for the telomerase recruitment defect observed in the absence of TPP1. Our findings indicate that TIN2-anchored TPP1 plays a major role in the recruitment of telomerase to telomeres in human cells and that recruitment does not depend on POT1 or interaction of the shelterin complex with the single-stranded region of the telomere.
منابع مشابه
Insight into the Regulation of Telomerase Access to Telomeres by Shelterin Proteins.docx
Recruitment to telomeres is a pivotal step in the function and regulation of human telomerase. Impaired telomerase function can lead to premature organismal aging, development of cancer and multisystem disorders such as dyskeratosis congenita. Telomerase access to telomeres may be regulated by a telomere-binding complex termed shelterin, which is composed of TRF1, TRF2, RAP1, TIN2, TPP1 and POT...
متن کاملTRF2-tethered TIN2 can mediate telomere protection by TPP1/POT1.
The shelterin protein TIN2 is required for the telomeric accumulation of TPP1/POT1 heterodimers and for the protection of telomeres by the POT1 proteins (POT1a and POT1b in the mouse). TIN2 also binds to TRF1 and TRF2, improving the telomeric localization of TRF2 and its function. Here, we ask whether TIN2 needs to interact with both TRF1 and TRF2 to mediate the telomere protection afforded by ...
متن کاملTPP1 OB-Fold Domain Controls Telomere Maintenance by Recruiting Telomerase to Chromosome Ends
Telomere synthesis in cancer cells and stem cells involves trafficking of telomerase to Cajal bodies, and telomerase is thought to be recruited to telomeres through interactions with telomere-binding proteins. Here, we show that the OB-fold domain of the telomere-binding protein TPP1 recruits telomerase to telomeres through an association with the telomerase reverse transcriptase TERT. When tet...
متن کاملIn vivo stoichiometry of shelterin components.
Human telomeres bind shelterin, the six-subunit protein complex that protects chromosome ends from the DNA damage response and regulates telomere length maintenance by telomerase. We used quantitative immunoblotting to determine the abundance and stoichiometry of the shelterin proteins in the chromatin-bound protein fraction of human cells. The abundance of shelterin components was similar in p...
متن کاملBinding of TPP1 protein to TIN2 protein is required for POT1a,b protein-mediated telomere protection.
The single-stranded DNA binding proteins in mouse shelterin, POT1a and POT1b, accumulate at telomeres as heterodimers with TPP1, which binds TIN2 and thus links the TPP1/POT1 dimers with TRF1 and TRF2/Rap1. When TPP1 is tethered to TIN2/TRF1/TRF2, POT1a is thought to block replication protein A binding to the single-stranded telomeric DNA and prevent ataxia telangiectasia and Rad3-related kinas...
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ورودعنوان ژورنال:
- Molecular and cellular biology
دوره 30 12 شماره
صفحات -
تاریخ انتشار 2010