Bioinformatics, Scientific Institute IRCCS E. MEDEA, 23842 Bosisio Parini, Italy.
Department of Physiopathology and Transplantation, University of Milan, 20090 Milan, Italy.
Nucleic Acids Res. 2018 Aug 21;46(14):7153-7168. doi: 10.1093/nar/gky494.
Telomeres protect the ends of eukaryotic chromosomes and are essential for cell viability. In mammals, telomere dynamics vary with life history traits (e.g. body mass and longevity), suggesting differential selection depending on physiological characteristics. Telomeres, in analogy to centromeric regions, also represent candidate meiotic drivers and subtelomeric DNA evolves rapidly. We analyzed the evolutionary history of mammalian genes implicated in telomere homeostasis (TEL genes). We detected widespread positive selection and we tested two alternative hypotheses: (i) fast evolution is driven by changes in life history traits; (ii) a conflict with selfish DNA elements at the female meiosis represents the underlying selective pressure. By accounting for the phylogenetic relationships among mammalian species, we show that life history traits do not contribute to shape diversity of TEL genes. Conversely, the evolutionary rate of TEL genes correlates with expression levels during meiosis and episodes of positive selection across mammalian species are associated with karyotype features (number of chromosome arms). We thus propose a telomere drive hypothesis, whereby (sub)telomeres and telomere-binding proteins are engaged in an intra-genomic conflict similar to the one described for centromeres.
端粒保护真核生物染色体的末端，对细胞存活至关重要。在哺乳动物中，端粒动力学随生命史特征（如体重和寿命）而变化，这表明根据生理特征存在差异选择。与着丝粒区域类似，端粒也代表候选减数分裂驱动因素，并且亚端粒 DNA 进化迅速。我们分析了参与端粒稳态的哺乳动物基因（TEL 基因）的进化历史。我们检测到广泛的正选择，并测试了两个替代假设：（i）生活史特征的变化驱动了快速进化；（ii）在雌性减数分裂中与自私 DNA 元件的冲突代表了潜在的选择压力。通过考虑哺乳动物物种之间的系统发育关系，我们表明生活史特征并不能导致 TEL 基因多样性的形成。相反，TEL 基因的进化率与减数分裂过程中的表达水平相关，并且哺乳动物物种之间的正选择事件与染色体组特征（染色体臂数量）相关。因此，我们提出了一个端粒驱动假说，即（亚）端粒和端粒结合蛋白参与类似于着丝粒描述的基因组内冲突。
