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. 2015 Apr 1;29(7):718–731. doi: 10.1101/gad.254144.114

Figure 6.

Figure 6.

Global reduction in H3K36me3 marking significantly increases gene expression change during aging and shortens life span. (A) H3K36me3 reduction in the met-1 mutant. Western blotting demonstrated a global reduction of H3K36me3 levels in met-1(n4337); glp-1(e2141) worms compared with glp-1(e2141). Quantifications of Western blot results are shown at the right. The Y-axis shows relative levels of H3K36me3 based on quantification of Western signals using a LiCor instrument. (B) Venn diagram representation of transcripts that show significant age-dependent mRNA expression change in control glp-1(e2141) or met-1(n4337); glp-1(e2141). Age-dependent mRNA expression change was computed using CuffDiff (Q-value < 0.05) based on RNA-seq data from two biological replicates. Two different statistical tests indicate that met-1(n4337); glp-1(e2141) worms showed significantly more gene expression change through aging compared with control worms (Z-test: 95% confidence interval: 0.26 ± 0.02; NcNemar's test: 811; P-value < 0.001). RNA-seq data are listed in Supplemental Tables S1 and S5. (C) Genes exhibiting age-dependent mRNA abundance change in glp-1(e2141) and met-1(n4337); glp-1(e2141) worms. Heat maps were generated using log2 values of age-dependent mRNA abundance fold change (D12/D2) in glp-1(e2141) and met-1(n4337); glp-1(e2141) worms from two independent biological experiments. Genes exhibiting significant age-dependent mRNA abundance change in both glp-1(e2141) and met-1(n4337); glp-1(e2141) worms (left), uniquely in met-1(n4337); glp-1(e2141) worms (middle), or uniquely in glp-1(e2141) worms (right) are shown. (D) Box plot comparing mRNA fold change of commonly identified transcripts in glp-1 and met-1; glp-1. The met-1; glp-1 strain showed a more dramatic change of mRNA levels in both the age-dependent decreased transcript group (left) and the age-dependent increased transcript group (right). Boxes represent the 25th, 50th (median), and 75th percentiles; whiskers are the 5th and 95th percentiles. (***) P-value < 2.2 × 10−16 (Wilcoxon signed-rank test). (E) Reduction of global H3K36me3 levels shortened life span. Survival curves of met-1(n4337); glp-1(e2141) and glp-1(e2141) worms fed with control L4440 or met-1 RNAi bacteria are shown. Quantitative data are presented in Supplemental Table S7. met-1 mutation shortened mean life span by ∼14%–22% (isolates 1 and 2) and maximum life span by ∼24%. met-1 RNAi treatment reduced mean life span by ∼13% (P-value < 0.001).