Centromeres depend on chromatin containing the conserved histone H3 variant CENP-A for function and inheritance, while the role of centromeric DNA repeats remains unclear. Retroelements are prevalent at centromeres across taxa and represent a potential mechanism for promoting transcription to aid in CENP-A incorporation or for generating RNA transcripts to maintain centromere integrity. In this study, we probe into the transcription and RNA localization of the centromere-enriched retroelement G2/Jockey-3 (hereafter referred to as Jockey-3) in Drosophila melanogaster, currently the only in vivo model with assembled centromeres. We find that Jockey-3 is a major component of the centromeric transcriptome and produces RNAs that localize to centromeres in metaphase. Leveraging the polymorphism of Jockey-3 and a de novo centromere system, we show that these RNAs remain associated with their cognate DNA sequences in cis, suggesting they are unlikely to perform a sequence-specific function at all centromeres. We show that Jockey-3 transcription is positively correlated with the presence of CENP-A and that recent Jockey-3 transposition events have occurred preferentially at CENP-A-containing chromatin. We propose that Jockey-3 preferentially inserts at the centromere to ensure its own selfish propagation, while contributing to transcription across these regions. Given the conservation of retroelements as centromere components through evolution, our findings may offer a basis for understanding similar associations in other species.

中文翻译：

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富含着丝粒的逆转录元件的转录和其 RNA 的局部保留是 CENP-A 染色质景观的重要特征


着丝粒的功能和遗传依赖于含有保守组蛋白 H3 变体 CENP-A 的染色质，而着丝粒 DNA 重复序列的作用仍不清楚。逆转录元件普遍存在于各个分类群的着丝粒中，代表了促进转录以帮助 CENP-A 掺入或产生 RNA 转录本以维持着丝粒完整性的潜在机制。在这项研究中，我们探讨了黑腹果蝇中富含着丝粒的逆转录元件 G2/Jockey-3 （以下简称 Jockey-3） 的转录和 RNA 定位，这是目前唯一具有组装着丝粒的体内模型。我们发现 Jockey-3 是着丝粒转录组的主要组分，并产生定位于中期着丝粒的 RNA。利用 Jockey-3 的多态性和从头着丝粒系统，我们表明这些 RNA 在顺式中仍与它们的同源 DNA 序列相关，这表明它们不太可能在所有着丝粒上执行序列特异性功能。我们表明 Jockey-3 转录与 CENP-A 的存在呈正相关，并且最近的 Jockey-3 转座事件优先发生在含有 CENP-A 的染色质上。我们建议 Jockey-3 优先插入着丝粒以确保其自身的自私繁殖，同时有助于这些区域的转录。鉴于逆转录元件在进化过程中作为着丝粒成分的保守性，我们的研究结果可能为理解其他物种的类似关联提供基础。