L1 drives HSC aging and affects prognosis of chronic myelomonocytic leukemia

Telomere(definition) attrition is one of the hallmark of aging. Lategeneration Terc knockout mice exhibit impaired hematopoiesis, 1 while the underling mechanisms remain poorly understood. Retrotransposon long interspersed element-1 (L1) is the only human retrotransposable elements capable of autonomous retrotransposition, and evolutionarily inactive. Recent studies reported that L1 is derepressed during the aging process with redistribution and reorganization of the heterochromatin. 2 Considering that telomere shortening can cause chromosome instability and rearrangements, 3 we speculate that L1 may play a role in impaired hematopoiesis in telomere dysfunctional mice.