Contrasting roles of transcription factors spineless and EcR in the highly dynamic chromatin landscape of butterfly wing metamorphosis

Background: We studied the chromatin accessibility landscsape in wings during butterfly metamorphosis, and investigate which transcription factors might be driving changes in accessibility Methods: We sequencing the Junonia coenia genome, and we studied chromatin accessibility using ATAC seq in multiple stages of wing development in both forewings and hindwings. For sites showing a large change in accessibility, we investigate which motifs are enriched, and correlate this with changes in gene expression of associated transcription factors. We confirm promising candidates with ChIP-seq Results: We find a highly dynamic landscape, with multiple peaks showing a double increase in accessibility throughout development. We show that transcription factor spineless, but not ecdysone receptor, is highly predictive of opening sites Conclusions: This work provides a characterization of the chromatin dynamics of insect wing metamorphosis, identifies novel candidate chromatin remodeling factors in insects, and provides the first genome assembly of the model butterfly Junonia coenia, with gene and cis-regulatory element annotations ChIP-seq from left and right hindwings at three developmental stages.

研究背景：本研究以蝴蝶变态发育过程中的翅膀为对象，解析其染色质开放景观（chromatin accessibility landscape），旨在探究介导染色质开放度变化的潜在转录因子（transcription factor）。
研究方法：本研究对模式蝴蝶蓖麻蛱蝶（Junonia coenia）的基因组开展测序，并利用ATAC测序（ATAC-seq）分析其前后翅在多个翅膀发育阶段的染色质开放度。针对开放度发生显著变化的染色质位点，我们鉴定其富集的结合基序（motif），并将该结果与相关转录因子的基因表达变化进行关联分析。此外，我们通过染色质免疫共沉淀测序（ChIP-seq）验证了具有潜力的候选调控因子。
研究结果：本研究揭示了高度动态的染色质开放景观，多个染色质峰在整个发育过程中呈现出开放度的双阶段提升。研究证实，转录因子spineless而非蜕皮激素受体（ecdysone receptor）可高度预测染色质开放位点的激活。
研究结论：本研究完成了昆虫翅膀变态发育过程中染色质动态变化的特征解析，鉴定出昆虫中潜在的新型染色质重塑因子；同时首次构建了模式蝴蝶蓖麻蛱蝶（Junonia coenia）的基因组组装，并完成了其基因与顺式调控元件（cis-regulatory element）的注释，此外还提供了三个发育阶段下左右后翅的染色质免疫共沉淀测序（ChIP-seq）数据集。