Different Phase of Telomere Shortening with Age in Peripheral Blood Mononuclear Cells

Kang, Ji Seon; Kook, Hoon; Yoon, Won Sang; Kim, Chan Jong; Hwang, Tai Ju

Abstract

PURPOSE: Telomeres, special protein and tandem repeat DNA structure that cap the ends of linear eukaryotic chromosomes, are essential for chromosome structure and stability. Human telomeric DNA is known to shorten by 30~200 bp with each somatic cell division. However, the phase of telomere changes has not been studied extensively.
METHODS
Telomere length was analyzed in the peripheral blood mononuclear cells (PBMCs) of 39 normal controls aged from newborn to 72 years by Southern blot hybridization using PharMingen's TeloQunatTM Telomere Length Assay Kit (Becton Dickinson Co.).
RESULTS
The mean telomere length of the population was 9.68 kb (range, 5.65~14.40 kb). The length (kb) decreased with age (A) by the following regression: T=10.86 0.04 A (T=telomere length in kb; A=age in years) (r= 0.38; P=0.016). The mean telomere lengths according to age groups were: 10.26 kb for less than 15 years; 9.92 kb for 16 to 40 years; 8.03 kb for over 40 years. The telomere length of over 40 years was significantly shorter than that of less than 15 years (P=0.013), and than that of 16 to 40 years (P=0.011). The phase of telomere changes was evaluated by age subgroups. The shortening was fastest in individuals of age <5, while the length showed a plateau or slight increment in age group between 5 to 35. The length decreased steadily with age by the regression of 12.43+/-0.07 A (r= 0.500; P=0.034) in age group over 35.
CONCLUSION
Telomere length of PBMCs decreases with age, and the different phase of telomere length shortening may suggest that the shortening of telomere is not a constant process over lifespan, but a dynamic process that is differently regulated in age groups.