RESUMEN
Telomere associations have been observed during key cellular processes such as mitosis, meiosis, and carcinogenesis and must be resolved before cell division to prevent genome instability. Here we establish that telomeric repeat-binding factor 1 (TRF1), a core component of the telomere protein complex, is a mediator of telomere associations in mammalian cells. Using live-cell imaging, we show that expression of TRF1 or yellow fluorescent protein (YFP)-TRF1 fusion protein above endogenous levels prevents proper telomere resolution during mitosis. TRF1 overexpression results in telomere anaphase bridges and aggregates containing TRF1 protein and telomeric DNA. Site-specific protein cleavage of YFP-TRF1 by tobacco etch virus protease resolves telomere aggregates, indicating that telomere associations are mediated by TRF1. This study provides novel insight into the formation and resolution of telomere associations.
Asunto(s)
Células Madre Embrionarias/ultraestructura , Telómero/metabolismo , Proteína 1 de Unión a Repeticiones Teloméricas/metabolismo , Animales , Proteínas Bacterianas/metabolismo , Ciclo Celular , Supervivencia Celular , Células Madre Embrionarias/metabolismo , Endopeptidasas/biosíntesis , Proteínas Luminiscentes/metabolismo , Ratones de la Cepa 129 , Mitosis , Proteolisis , Proteínas Recombinantes de Fusión/metabolismo , Telómero/ultraestructuraRESUMEN
Telomere maintenance and DNA repair are important processes that protect the genome against instability. mRtel1, an essential helicase, is a dominant factor setting telomere length in mice. In addition, mRtel1 is involved in DNA double-strand break repair. The role of mRtel1 in telomere maintenance and genome stability is poorly understood. Therefore we used mRtel1-deficient mouse embryonic stem cells to examine the function of mRtel1 in replication, DNA repair, recombination, and telomere maintenance. mRtel1-deficient mouse embryonic stem cells showed sensitivity to a range of DNA-damaging agents, highlighting its role in replication and genome maintenance. Deletion of mRtel1 increased the frequency of sister chromatid exchange events and suppressed gene replacement, demonstrating the involvement of the protein in homologous recombination. mRtel1 localized transiently at telomeres and is needed for efficient telomere replication. Of interest, in the absence of mRtel1, telomeres in embryonic stem cells appeared relatively stable in length, suggesting that mRtel1 is required to allow extension by telomerase. We propose that mRtel1 is a key protein for DNA replication, recombination, and repair and efficient elongation of telomeres by telomerase.
Asunto(s)
ADN Helicasas/genética , ADN Helicasas/metabolismo , Reparación del ADN , Replicación del ADN , Homeostasis del Telómero , Telómero/fisiología , Animales , Células Cultivadas , ADN/genética , Daño del ADN , Células Madre Embrionarias/citología , Células Madre Embrionarias/metabolismo , Femenino , Técnicas de Sustitución del Gen , Inestabilidad Genómica , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Intercambio de Cromátides Hermanas , Telomerasa/metabolismoRESUMEN
Telomere maintenance and DNA repair are crucial processes that protect the genome against instability. RTEL1, an essential iron-sulfur cluster-containing helicase, is a dominant factor that controls telomere length in mice and is required for telomere integrity. In addition, RTEL1 promotes synthesis-dependent strand annealing to direct DNA double-strand breaks into non-crossover outcomes during mitotic repair and in meiosis. Here, we review the role of RTEL1 in telomere maintenance and homologous recombination and discuss models linking RTEL1's enzymatic activity to its function in telomere maintenance and DNA repair.