The role of angiogenin in tRNA cleavage during Kaposi sarcoma-associated herpesvirus reactivation.

Kaposi sarcoma-associated herpesvirus (KSHV) is a human gammaherpesvirus and the etiological agent of several human cancers, including Kaposi sarcoma and primary effusion lymphoma. KSHV reprograms gene expression in the infected host, leading to gene dysregulation that promotes oncogenesis. We explored how KSHV reactivation leads to the alteration of host transfer RNA (tRNA) expression and the mechanisms by which these changes occur. Here, we present data indicating that tRNAs undergo cleavage into tRNA fragments (tRFs) upon KSHV reactivation in latently infected TREX-BCBL-1-RTA B-cells. tRFs are gaining recognition as inducible effector RNAs that appear during stress, cancer, and infection. KSHV reactivation primarily induced 5’ tRNA halves (tiRNAs). KSHV reactivation primarily induced 5’ tRNA halves (tiRNAs). tiRNAs are formed by cleavage at the tRNA anticodon loop, typically by angiogenin (ANG) in response to cellular stress. We used stem-loop RT-qPCR to validate one of the highest upregulated tRFs, 5’ tiRNA-Gly-GCC, and demonstrated that its biogenesis is independent of ANG. We also found that knockdown or knockout of ANG did not impact viral gene expression despite its published role in supporting latency. Overall, we found no evidence to support the idea that tRNA cleavage by ANG plays a role in KSHV reactivation. This work lends insight into the role of ANG in tRF biogenesis and the KSHV lytic cycle.