title: Distinct roles of TRF1 in the regulation of telomere structure and lengthening.
abstract: The telomere is a functional chromatin structure that consists of G-rich repetitive sequences and various associated proteins. Telomeres protect chromosomal ends from degradation, provide escape from the DNA damage response, and regulate telomere lengthening by telomerase. Multiple proteins that localize at telomeres form a complex called shelterin/telosome. One component, TRF1, is a double-stranded telomeric DNA binding protein. Inactivation of TRF1 disrupts telomeric localization of other shelterin components and induces chromosomal instability. Here, we examined how the telomeric localization of shelterin components is crucial for TRF1-mediated telomere-associated functions. We found that many of the mTRF1 deficient phenotypes, including chromosomal instability, growth defects, and dysfunctional telomere damage response, were suppressed by the telomere localization of shelterin components in the absence of functional mTRF1. However, abnormal telomere signals and telomere elongation phenotypes were either not rescued or only partially rescued, respectively. These data suggest that TRF1 regulates telomere length and function by at least two mechanisms; in one TRF1 acts through the recruiting/tethering of other shelterin components to telomeres, and in the other TRF1 seems to play a more direct role.
authors.affiliation: Experimental Research Center for Infectious Diseases, Institute for Virus Research, and Graduate School of Biostudies, Kyoto University, 53 Shogoin, Kawara-cho, Sakyo-ku, Kyoto, Japan.
authors.forename: Keiji
authors.initials: K
authors.lastname: Okamoto
authors.forename: Tomohiko
authors.initials: T
authors.lastname: Iwano
authors.forename: Makoto
authors.initials: M
authors.lastname: Tachibana
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Shinkai
mesh_terms: D000818:Animals; D002460:Cell Line; D002645:Chickens; D043171:Chromosomal Instability / Q000235:genetics; D033481:Chromosomes, Mammalian / Q000235:genetics / Q000378:metabolism*; D004249:DNA Damage / Q000235:genetics; D051379:Mice; D016615:Telomere / Q000235:genetics / Q000378:metabolism*; D035321:Telomeric Repeat Binding Protein 1 / Q000235:genetics / Q000378:metabolism*
chemical_list: D035321:Telomeric Repeat Binding Protein 1