Turnover of mRNA in the cytoplasm of human cells is thought to be redundantly 
conducted by the monomeric 5'-3' exoribonuclease hXRN1 and the 3'-5' 
exoribonucleolytic RNA exosome complex. However, in addition to the 
exosome-associated 3'-5' exonucleases hDIS3 and hDIS3L, the human genome encodes 
another RNase II/R domain protein-hDIS3L2. Here, we show that hDIS3L2 is an 
exosome-independent cytoplasmic mRNA 3'-5' exonuclease, which exhibits 
processive activity on structured RNA substrates in vitro. hDIS3L2 associates 
with hXRN1 in an RNA-dependent manner and can, like hXRN1, be found on 
polysomes. The impact of hDIS3L2 on cytoplasmic RNA metabolism is revealed by an 
increase in levels of cytoplasmic RNA processing bodies (P-bodies) upon hDIS3L2 
depletion, which also increases half-lives of investigated mRNAs. Consistently, 
RNA sequencing (RNA-seq) analyses demonstrate that depletion of hDIS3L2, like 
downregulation of hXRN1 and hDIS3L, causes changed levels of multiple mRNAs. We 
suggest that hDIS3L2 is a key exosome-independent effector of cytoplasmic mRNA 
metabolism.