Fixed-tissue ChIP-seq for H3K27 acetylation (H3K27ac) profiling (FiTAc-seq) is an epigenetic method for profiling active enhancers and promoters in formalin-fixed, paraffin-embedded (FFPE) tissues. We previously developed a modified ChIP-seq protocol (FiT-seq) for chromatin profiling in FFPE. FiT-seq produces high-quality chromatin profiles particularly for methylated histone marks but is not optimized for H3K27ac profiling. FiTAc-seq is a modified protocol that replaces the proteinase K digestion applied in FiT-seq with extended heating at 65 °C in a higher concentration of detergent and a minimized sonication step, to produce robust genome-wide H3K27ac maps from clinical samples. FiTAc-seq generates high-quality enhancer landscapes and super-enhancer (SE) annotation in numerous archived FFPE samples from distinct tumor types. This approach will be of great interest for both basic and clinical researchers. The entire protocol from FFPE blocks to sequence-ready library can be accomplished within 4 d.

用于H3K27乙酰化（H3K27ac）分析（FiTAc-seq）的固定组织ChIP-seq是在福尔马林固定，石蜡包埋（FFPE）组织中分析活性增强子和启动子的表观遗传方法。我们以前开发了一种改进的ChIP-seq协议（FiT-seq），用于FFPE中的染色质分析。FiT-seq可以产生高质量的染色质图谱，特别是用于甲基化的组蛋白标记，但并未针对H3K27ac分析进行优化。FiTAc-seq是一种经过修改的方案，可通过在65°C下以较高浓度的去污剂延长加热时间并以最小化的超声处理步骤取代FiT-seq中应用的蛋白酶K消化，从而从临床样品中生成完整的全基因组H3K27ac图。FiTAc-seq在来自不同肿瘤类型的许多FFPE存档样本中生成高质量的增强子图谱和超增强器（SE）注释。对于基础研究人员和临床研究人员而言，这种方法都将引起极大的兴趣。从FFPE块到序列就绪库的整个协议可在4天内完成。