GSE131658
Cis- and trans-regulation of alternative splicing by Adenosine Deaminase Acting on the double-stranded RNA (ADAR) proteins
RNA editing and splicing are the two major processes that dynamically regulate human transcriptome diversity. Despite growing evidence of crosstalk between RNA editing enzymes (mainly ADAR1) and splicing machineries, detailed mechanistic explanations and their biological importance in diseases, such as cancer are still lacking. Herein, we identify approximately a hundred high-confidence splicing events altered by ADAR1 and/or ADAR2, and ADAR1 or ADAR2 protein can regulate cassette exons in both directions. We unravel a binding tendency of ADARs to dsRNAs that involves GA-rich sequences for editing and splicing regulation. ADAR1 edits an intronic splicing silencer, leading to recruitment of SRSF7 and repression of exon inclusion. We also present a mechanism through which ADAR2 binds to dsRNA formed between GA-rich sequences and polypyrimidine (Py)-tract and precludes access of U2AF65 to 3' splice site. Furthermore, we find these ADARs-regulated splicing changes per se influence tumorigenesis, not merely byproducts of ADARs editing and binding. Overall design: We constructed strand-specific cDNA libraries of 8 total RNA samples and sequenced the libraries using Illumina Hiseq4000 platform achieving over 200 millions of mappable reads per sample. Then we examined alternative splicing in EC109 cells after depletion or overexpression of ADAR1 or ADAR2.