Divergence in alternative polyadenylation between humans and chimpanzees contributes to gene regulatory differences between species

Differences in gene regulation contribute to phenotypic differences between humans and other primates. While co-transcriptional gene regulatory mechanisms such as alternative polyadenylation (APA) can help explain how variation in gene regulation manifests, such mechanisms remain understudied. We measured polyadenylation site (PAS) usage in a panel of 6 human and 6 chimpanzee lymphoblastoid cell lines (LCLs). While APA is largely conserved between humans and chimpanzees, genes with divergent APA patterns are enriched among differentially expressed and differentially translated genes. Differential usage of 3’ UTR and intronic PAS are both significantly correlated with differential mRNA expression effect sizes but in opposite directions. For many genes, there is one PAS dominant, meaning it is used much more often than others. The dominant PAS for these gene is overwhelmingly shared between species, however, differences in dominant PAS are enriched for genes with expression differences. Finally, through post-translational mechanisms, we believe APA contributes to genes differentially expressed at the protein level but not in mRNA. As this is the first primate comparative study of APA, our study establishes APA as a key mechanism underlying the genetic regulation of gene and protein expression levels in primates. We measured polyadenylation site (PAS) usage in a panel of 6 human and 6 chimpanzee lymphoblastoid cell lines (LCLs). We collected 3' Seq on total and nuclear mRNA using the Lexogen Rev Quant Seq protocol. We collected RNA sequencing on the total mRNA using the Illumina TruSeq kit.