The Shortest Telomere, Not Average Telomere Length, Is Critical for Cell Viability and Chromosome Stability

Abstract

Loss of telomere function can induce cell cycle arrest and apoptosis. To investigate the processes that trig- ger cellular responses to telomere dysfunction, we crossed mTR����/���� G6 mice that have short telomeres with mice heterozygous for telomerase (mTR����/����) that have long telomeres. The phenotype of the telomerase null offspring was similar to that of the late generation parent, although only half of the chromosomes were short. Strikingly, spectral karyotyping (SKY) analysis revealed that loss of telomere function occurred pref- erentially on chromosomes with critically short telo- meres. Our data indicate that, while average telomere length is measured in most studies, it is not the aver- age but rather the shortest telomeres that constitute telomere dysfunction and limit cellular survival in the absence of telomerase.