The Role of tRNA Fragments on Neurogenesis Alteration by H₂O₂-induced Oxidative Stress.

Transfer RNAs (tRNAs) are small non-coding RNA molecules transcribed from tRNA genes. tRNAs cleaved into a diverse population tRNA fragments (tRFs) ranging in length from 18 to 40 nucleotides, they interact with RNA binding proteins and influence the stability and translation. Stress is one of the reasons for tRFs cleavage. In our study, we modeled oxidative stress conditions with hydrogen peroxide (H(2)O(2)) exposure and dealt with one of the frequently expressed tRF in the hippocampus region of the brain, which is tRF-Glu-CTC. For this purpose, neural stem cells (NSCs) were exposed to H(2)O(2), and tRF-Glu-CTC levels were increased in various H(2)O(2) concentrations. A decrease was seen in microtubule-associated protein 2 (MAP2) marker expression. To understand the H(2)O(2) oxidative stress condition on the expression of tRNA fragments, 72 hpf zebrafish embryos exposed to different H(2)O(2) concentrations, an increase in the level of tRF-Glu-CTC was observed in all concentrations of H(2)O(2) compared to control. Subsequently, neurogenesis markers were figured out via Calb2a (calbindin 2a) in situ hybridization (ISH) and HuC/D immunofluorescence staining (IF) staining experiments. Under H(2)O(2) exposure, a decline was observed in Calb2a and HuC/D markers. To understand the inhibitory role of tRF-Glu-CTC on neurogenesis, NSCs were transfected via tRF-Glu-CTC inhibitor, and neurogenesis markers (ßIII-tubulin, MAP2, and GFAP) were determined with qRT-PCR and IF staining. tRF-Glu-CTC inhibitor reversed the diminished neuronal markers expression under the exposure of H(2)O(2). Gene Ontology (GO) enrichment analysis showed us that targets of tRF-Glu-CTC are generally related to neuronal function and synaptic processes.