Type II tRNA cleavage by SLFN14 endoribonuclease variants linked to inherited thrombocytopenia drives global translational repression

Schlafens proteins (SLFNs) are interferon-inducible regulators of RNA metabolism that influence antiviral defense and cell fate. Human SLFN14 is a ribosome-associated endoribonuclease whose pathogenic variants cause autosomal dominant inherited thrombocytopenia (IT), but the molecular basis of this disorder remains unclear. Here, using HEK293T cells expressing human SLFN14 variants, we show that SLFN14 represses global protein synthesis through selective cleavage of type II tRNAs. IT-linked mutations alter SLFN14 RNA substrate specificity, enhancing depletion of type II tRNAs while reducing rRNA cleavage. This shift promotes ribosome stalling at codons decoded by type II tRNAs, triggering global translational arrest, stress signaling, and cell death. These findings reveal how altered RNA targeting by SLFN14 can drive disease and highlight selective tRNA targeting as a mechanism than regulates translation and cell fate.