Choreographing telomeres

A histone variant involved in DNA repair and phosphorylated in response to critically short telomeres is nonetheless not involved in most aspects of telomere maintenance, according to Fernandez-Capetillo et al. (page 15). Their results suggest that this histone, H2AX, instead choreographs meiotic telomere movements.Telomeres at the ends of DNA strands are protected by proteins that prevent chromosome fusions. If these proteins are perturbed or if telomeres are severely shortened, the DNA damage response is triggered, repair factors are recruited to telomeres, H2AX is phosphorylated, and chromosome fusions and cell senescence often ensue. H2AX is a target of the ATM kinase, which itself helps to protect shortened telomeres from fusion events.

Given this background, the authors expected that H2AX might also function in telomere maintenance. Instead they found that H2AX mutant cells had telomeres...