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Updated: Oct 28, 2026
The Mammalian Ocular Lens in Focus: Development, Anatomy, Physiology, Transparency, Biomechanics, and Age-Related Challenges
Published on: May 29, 2026
Biphasic tRF-31 dynamics regulate HIPK2-mediated dual-track lens epithelial injury under oxidative stress in
Zicai Pan1, Yuchen Jin1, Chengshou Zhang2
1Eye Center of Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310009, Zhejiang, China.
Abstract:
Age-related cataract (ARC) develops through cumulative oxidative stress and progressive loss of lens epithelial homeostasis, but the small-RNA mechanisms that distinguish an adaptive response from sustained injury remain unclear. Using a time-resolved H2O2 model in HLEC-B3 cells, we identified tRF-31, a 31-nt 5' tRNA-Ala-derived small RNA, as a biphasic stress-responsive regulator that increased during an early oxidative-response state with preserved viability but declined during sustained sublethal injury. N-acetylcysteine blunted the early increase and counteracted the later decrease in tRF-31, whereas the full-length parental tRNA-Ala pool remained stable and quantitative immunofluorescence showed stress-dependent angiogenin redistribution that was temporally associated with tRF-31 expression. Functionally, tRF-31 replenishment reduced apoptosis and mitochondrial depolarization while supporting post-stress epithelial recovery and DNA synthesis, whereas tRF-31 inhibition aggravated apoptotic and mitochondrial injury after endogenous tRF-31 had declined. Transcriptomic profiling, target prediction, quantitative PCR validation, and wild-type and mutant 3'untranslated region reporter assays supported homeodomain-interacting protein kinase 2 (HIPK2) as a direct target of tRF-31. tRF-31 suppressed HIPK2 and p53 Ser46 phosphorylation, reduced BAX, BAD, p21, and cleaved caspase-3, and preserved Bcl-2, RB phosphorylation, CCNE2, and PCNA. HIPK2 overexpression counteracted the anti-apoptotic and pro-recovery effects of tRF-31 mimic. In 92 ARC anterior capsule specimens, lower tRF-31, higher HIPK2 and CDKN1A expression, and a higher BAX/Bcl-2 ratio were associated with greater nuclear hardness and poorer preoperative visual acuity after adjustment for age. These findings identify a temporally regulated tRF-31/HIPK2-p53 axis that links oxidative stress responses to lens epithelial injury and impaired recovery in ARC.
