title: LIM-domain proteins TRIP6 and LPP associate with shelterin to mediate telomere protection.
abstract: POT1 is the single stranded telomeric overhang binding protein, and is part of the shelterin complex, a group of six proteins essential for proper telomere function. The reduction or abrogation of POT1 DNA binding activity in mammalian cells results in telomere elongation, or activation of the ATR DNA damage response at telomeres. Therefore, overhang binding represents the functionally relevant activity of POT1. To better understand the roles of POT1, we sought to isolate proteins that interact with the DNA binding domain of the protein. A yeast two-hybrid screen was implemented using a C-terminal truncation termed POT1DeltaC, retaining the DNA binding domain. This screen yielded a partial cDNA corresponding to TRIP6, a member of the LIM domain protein family. TRIP6 could co-immunoprecipitate with POT1, TRF2 and TIN2 in human cells, arguing for association with the whole shelterin complex, and was detected at telomeres by ChIP. TRIP6 depletion by siRNA led to the induction of telomere dysfunction induced foci (TIFs), indicating a role in telomere protection. A closely related LIM domain protein, LPP, was also found at telomeres and was also important for repressing the DNA damage response. We propose that TRIP6 and LPP are both required for telomere protection.
authors.affiliation: Department of Biological Sciences Hunter College, New York, NY 10065, USA.
authors.forename: Samantha A
authors.initials: SA
authors.lastname: Sheppard
authors.forename: Diego
authors.initials: D
authors.lastname: Loayza
mesh_terms: D000074183:ATPases Associated with Diverse Cellular Activities; D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism*; D003598:Cytoskeletal Proteins / Q000378:metabolism*; D004249:DNA Damage; D004268:DNA-Binding Proteins / Q000502:physiology; D006801:Humans; D060588:LIM Domain Proteins; D046988:Proteasome Endopeptidase Complex; D011485:Protein Binding; D000089804:Shelterin Complex; D016615:Telomere / Q000473:pathology / Q000502:physiology; D034501:Telomere-Binding Proteins / Q000378:metabolism* / Q000502:physiology; D014157:Transcription Factors / Q000378:metabolism*; D015003:Yeasts / Q000235:genetics
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D003598:Cytoskeletal Proteins; D004268:DNA-Binding Proteins; D060588:LIM Domain Proteins; C103594:LPP protein, human; C440849:POT1 protein, human; C092282:PSMC5 protein, human; D000089804:Shelterin Complex; D034501:Telomere-Binding Proteins; D014157:Transcription Factors; D046988:Proteasome Endopeptidase Complex; D000074183:ATPases Associated with Diverse Cellular Activities