Do Telomeres Adapt to Physiological Stress? Exploring the Effect of Exercise on Telomere Length and Telomere-Related Proteins

Figure 2

Telomere-related proteins. Telomere DNA sequences are bound by and interact with several proteins. These proteins and the enzyme telomerase function to regulate telomere length and prevent inappropriate recognition of telomere DNA by the DNA damage response machinery. (A) Telomerase is a ribonucleoprotein consisting of two core components: a catalytically active reverse transcriptase component, TERT and a noncoding RNA template, TERC. Together with several other cofactors such as dyskerin, GAR1, NOP10, and NHP2, telomerase functions to add telomere repeats to the ends of telomeres. (B) A complex of six proteins termed “shelterin” binds to telomere DNA in a tightly regulated stoichiometry and functions to regulate telomere length by preventing inappropriate telomere elongation by telomerase. Telomere repeat binding factors (TRFs) 1 and 2 bind to telomere double-stranded DNA and function to regulate telomere length and T-loop formation. (C) Shelterin also functions to prevent the DNA damage machinery from recognizing telomeres. Both POT1 and TRF2 prevent the telomere from being recognized by DNA damage kinases.