Department of Biology and Biotechnology "Lazzaro Spallanzani", University of Pavia, 27100 Pavia, Italy.
Oasi di Sant'Alessio, Sant'Alessio con Vialone, 27016 Pavia, Italy.
Int J Mol Sci. 2023 Feb 18;24(4):4134. doi: 10.3390/ijms24044134.
In mammals, centromeres are epigenetically specified by the histone H3 variant CENP-A and are typically associated with satellite DNA. We previously described the first example of a natural satellite-free centromere on chromosome 11 (ECA11) and, subsequently, on several chromosomes in other species of the genus . We discovered that these satellite-free neocentromeres arose recently during evolution through centromere repositioning and/or chromosomal fusion, after inactivation of the ancestral centromere, where, in many cases, blocks of satellite sequences were maintained. Here, we investigated by FISH the chromosomal distribution of satellite DNA families in (EPR), demonstrating a good degree of conservation of the localization of the major horse satellite families 37cen and 2PI with the domestic horse. Moreover, we demonstrated, by ChIP-seq, that 37cen is the satellite bound by CENP-A and that the centromere of EPR10, the ortholog of ECA11, is devoid of satellite sequences. Our results confirm that these two species are closely related and that the event of centromere repositioning which gave rise to EPR10/ECA11 centromeres occurred in the common ancestor, before the separation of the two horse lineages.
在哺乳动物中，着丝粒通过组蛋白 H3 变体 CENP-A 被表观遗传指定，通常与卫星 DNA 相关联。我们之前描述了第一个自然无卫星着丝粒的例子，即 11 号染色体（ECA11），随后在该属的其他物种的几个染色体上也发现了这种无卫星的新着丝粒。我们发现，这些无卫星的新着丝粒是在祖先着丝粒失活后，通过着丝粒重定位和/或染色体融合，在进化过程中最近产生的，在许多情况下，卫星序列块得以保留。在这里，我们通过 FISH 研究了 （EPR）中卫星 DNA 家族的染色体分布，证明了主要马卫星家族 37cen 和 2PI 与家马在定位上具有很好的保守性。此外，我们通过 ChIP-seq 证明 37cen 是被 CENP-A 结合的卫星，并且 EPR10 的着丝粒（ECA11 的同源物）没有卫星序列。我们的结果证实，这两个物种密切相关，导致 EPR10/ECA11 着丝粒的着丝粒重定位事件发生在两个马谱系分离之前的共同祖先中。
