用Transformer生成特定细胞类型的调控DNA序列,效率更高且更少记忆训练数据。
Continuous Diffusion Transformers for Designing Synthetic Regulatory Elements
- 用2D CNN编码器+Transformer去噪器替代U-Net,提升生成效率
- 13轮训练即达最优损失,记忆率从5.3%降至1.7%
- 结合奖励模型微调,预测活性提升38倍,效果真实可靠
我们提出一种参数高效的扩散Transformer(DiT),用于生成200bp的细胞类型特异性调控DNA序列。通过将DNA-Diffusion中的U-Net主干替换为配备2D CNN输入编码器的Transformer去噪器,模型在13个训练周期内达到U-Net的最佳验证损失(减少60倍),收敛误差降低39%,同时通过BLAT比对将生成序列对训练数据的记忆率从5.3%降至1.7%。消融实验表明,CNN编码器至关重要:无此结构时,无论使用何种位置编码,验证损失均上升70%。我们进一步采用基于Enformer的DDPO微调方法,使预测调控活性提升38倍。在独立预测任务中与DRAKES交叉验证的结果表明,性能提升反映的是真实的调控信号,而非奖励模型过拟合。
原文摘要 · Abstract (English)
We present a parameter-efficient Diffusion Transformer (DiT) for generating 200bp cell-type-specific regulatory DNA sequences. By replacing the U-Net backbone of DNA-Diffusion with a transformer denoiser equipped with a 2D CNN input encoder, our model matches the U-Net's best validation loss in 13 epochs (60$\times$ fewer) and converges 39% lower, while reducing memorization from 5.3% to 1.7% of generated sequences aligning to training data via BLAT. Ablations show the CNN encoder is essential: without it, validation loss increases 70% regardless of positional embedding choice. We further apply DDPO finetuning using Enformer as a reward model, achieving a 38$\times$ improvement in predicted regulatory activity. Cross-validation against DRAKES on an independent prediction task confirms that improvements reflect genuine regulatory signal rather than reward model overfitting.
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