Dysregulated H3K27 Acetylation Is Implicated in Fatty Liver Hemorrhagic Syndrome in Chickens

Figures

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  FIGURE 1. Anatomical and histopathological images of the liver in chickens. (A) Liver tissue of healthy chickens. (B) Liver tissue of FLHS chickens. (C) Histopathological section of the liver from the healthy group. (D) Histopathological section of the liver of the FLHS group. Scale bars = 100 μm.

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  FIGURE 2. Distinct transcriptional signature between healthy and FLHS chickens. (A) Pearson correlation coefficient for each pair of biological replicates in RNA-Seq. (B) Volcano plot of top significant differentially expressed genes between healthy and FLHS chickens. The red and blue dot indicates upregulated gene and downregulated gene, respectively.

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  FIGURE 3. Mapping in vivo H3K27ac mark across genomic features via ChIP-Seq. (A) Pearson correlation coefficient for each pair of biological replicates in ChIP-Seq. (B) Breakdown on proximal and distal enrichment across genome in the healthy and FLHS. (C) The distribution of the H3K27ac peaks among each intron.

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  FIGURE 4. Differential H3K27ac peaks associated with FLHS in the liver. (A) Top 10 significant differential H3K27ac peaks between healthy and FLHS chickens. (B) Representative validation of differential peaks exhibiting distinct activity of the H3K27ac signal across healthy and FLHS chickens.

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  FIGURE 5. Functional annotation of H3K27ac ChIP-Seq and RNA-Seq between healthy and FLHS groups. (A) Functional enrichment of biological processes of putative target genes associated with differentially poorly and highly acetylated peaks. (B) Regulation terms of putative target genes of differentially poorly and highly acetylated peaks.

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  FIGURE 6. ChIP-qPCR and RT-PCR validation of peak-associated target genes. (A–E) ChIP-qPCR fold enrichment of PCK1, APOA1, ANGPTL4, FABP1, and KIT genes in FLHS pathological chickens relative to control individuals. (F–J) The mRNA expression levels of PCK1, APOA1, ANGPTL4, FABP1, and KIT genes in FLHS pathological chickens relative to control individuals. Expression levels were determined as the fold change in 2–Δ Δ Ct levels relative to the control group with median expression set to 1. Significance was assessed by t-test, *P ≤ 0.05, **P ≤ 0.01.

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  FIGURE 7. A proposed model on the epigenetic regulation mechanisms of histone H3K27 acetylation causing the FLHS in laying hens. Mediated by histone-modifying enzyme, HELP could have an impact on histone modification of H3K27ac and chromatin structure, leading to the dysregulation of genes related to lipid and energy metabolism (PCK1, APOA1, ANGPTL4, and FABP1) and immune response (FGF7, PDGFRA, and KIT), and PPAR signaling pathway, which may cause the excessive accumulation of fat in liver tissue and induce the development of the FLHS.