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Pif1 regulates telomere length by preferentially removing telomerase from long telomere ends.

ABSTRACT: Telomerase, a ribonucleoprotein complex, is responsible for maintaining the telomere length at chromosome ends. Using its RNA component as a template, telomerase uses its reverse transcriptase activity to extend the 3'-end single-stranded, repetitive telomeric DNA sequence. Pif1, a 5'-to-3' helicase, has been suggested to regulate telomerase activity. We used single-molecule experiments to directly show that Pif1 helicase regulates telomerase activity by removing telomerase from telomere ends, allowing the cycling of the telomerase for additional extension processes. This telomerase removal efficiency increases at longer ssDNA gaps and at higher Pif1 concentrations. The enhanced telomerase removal efficiency by Pif1 at the longer single-stranded telomeric DNA suggests a way of how Pif1 regulates telomerase activity and maintains telomere length.

SUBMITTER: Li JR

PROVIDER: S-EPMC4117769 | biostudies-literature | 2014 Jul

REPOSITORIES: biostudies-literature

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Pif1 regulates telomere length by preferentially removing telomerase from long telomere ends.

Li Jing-Ru JR Yu Tai-Yuan TY Chien I-Chieh IC Lu Chia-Ying CY Lin Jing-Jer JJ Li Hung-Wen HW

Nucleic acids research 20140630 13

Telomerase, a ribonucleoprotein complex, is responsible for maintaining the telomere length at chromosome ends. Using its RNA component as a template, telomerase uses its reverse transcriptase activity to extend the 3'-end single-stranded, repetitive telomeric DNA sequence. Pif1, a 5'-to-3' helicase, has been suggested to regulate telomerase activity. We used single-molecule experiments to directly show that Pif1 helicase regulates telomerase activity by removing telomerase from telomere ends, a ...[more]

PMID: 24981509

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Relationship between physical activity level, telomere length, and telomerase activity.

Project description:PurposeThe purpose of this study was to examine the relationship of exercise energy expenditure (EEE) with both telomere length and telomerase activity in addition to accounting for hTERT C-1327T promoter genotype.MethodsSixty-nine (n = 34 males; n = 35 females) participants 50-70 yr were assessed for weekly EEE level using the Yale Physical Activity Survey. Lifetime consistency of EEE was also determined. Subjects were recruited across a large range of EEE levels and separated into quartiles: 0-990, 991-2340, 2341-3540, and >3541 kcal x wk(-1). Relative telomere length and telomerase activity were measured in peripheral blood mononuclear cells (PBMC).ResultsThe second EEE quartile exhibited significantly longer telomere lengths [1.12 +/- 0.03 relative units (RU)] than both the first and fourth EEE quartiles (0.94 +/- 0.03 and 0.96 +/- 0.03 RU, respectively; P < 0.05) but was not different from the third quartile. Telomerase activity was not different among the EEE quartiles. An association was observed between telomerase enzyme activity and hTERT genotype with the TT genotype (1.0 x 10(-2) +/- 4.0 x 10(-3) attomoles (amol) per 10,000 cells; n = 19) having significantly greater telomerase enzyme activity than both the CT (1.3 x 10(-3) +/- 3.2 x 10(-3); n = 30) and CC groups (5.0 x 10(-4) +/- 3.9 x 10(-3); n = 20; P = 0.01).ConclusionThese results indicate that moderate physical activity levels may provide a protective effect on PBMC telomere length compared with both low and high EEE levels.

| S-EPMC2581416 | biostudies-literature

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