Review Volume 11, Issue 21 pp 9932—9946

Emerging roles of piRNAs in cancer: challenges and prospects

Figure 3. piRNA function. (A) Transposon silencing. At TGS level, Lsd1 removes activating H3K4me2 marks from promoter regions, Egg and Wde H3K9me3 marks to the target DNA, HP1 lead to heterochromatin formation, DNMT methylate genic CpG sites. After the mature piRNA-piwi complex is formed in the cytoplasm. (B) piRNAs/piwi complex-protein interaction. The interaction between piRNAs/piwi and proteins alter the subcellular localization of proteins and facilitate the interaction of multiple proteins. (C) At PTGS level, the piRNAs/piwi complex bind to targeted RNAs and impede their function by sequence complementary. Abbreviations: TGS: transcription gene silencing; PTGS: post-transcription gene silencing; H3K9me3: histone 3 lysine 9 trimethylation; H3K4me2: histone 3 lysine 4 dimethylation; Lsd1: Lysine-specific demethylase1; Egg: Eggless; Wde: Windei; HP1: heterochromatin protein 1; DNMT: DNA methyltransferase.