tRF-AspGTC promotes intracranial aneurysm formation by regulating TRIM29-mediated galectin-3 ubiquitination

Background

Intracranial aneurysm (IA) is a common cerebrovascular disorder characterized by abnormal dilation of the cerebral arterial wall, with an estimated prevalence of approximately 3.2% in the general population. The rupture of IA can lead to subarachnoid hemorrhage, which carries a high mortality rate of up to 40% and a disability rate of up to 50%, posing a significant public health threat. Transfer RNA-derived small RNAs (tsRNAs) are a newly identified class of small non-coding RNAs generated from precursor or mature transfer RNAs (tRNAs) through cleavage mediated by ribonucleases. TsRNAs possess several intrinsic advantages, including high stability and abundant expression levels, making them promising candidates for regulating various biological processes and serving as potential biomarkers. However, the role of tsRNAs in IA remains largely unexplored.

Results

First, the study explored the most significantly differentially expressed tsRNA in IA. Through sequencing and experimental validation, the research team found that tRF-AspGTC was significantly upregulated in IA tissues and was primarily localized to vascular smooth muscle cells (VSMCs). Multivariate logistic regression analysis further indicated that tRF-AspGTC is an independent risk factor for IA development. ROC analysis confirmed its high efficiency in diagnosing IA. Knockdown and overexpression experiments in VSMCs demonstrated that tRF-AspGTC promotes VSMC phenotypic transformation, enhances the expression of MMP9 and IL-1β, and facilitates ROS generation.

Subsequently, the study revealed the molecular mechanism by which tRF-AspGTC regulates the function of VSMCs. Through RNA pulldown combined with mass spectrometry analysis, the researchers identified that tRF-AspGTC specifically binds to galectin-3. Moreover, tRF-AspGTC was found to regulate the protein level of galectin-3 without affecting its mRNA expression, suggesting that it may modulate galectin-3 expression through influencing protein degradation pathways. Further investigation revealed that tRF-AspGTC regulates the ubiquitination of galectin-3 via the ubiquitin ligase TRIM29, thereby affecting its stability and ultimately activating the TLR4/MyD88/NF-κB signaling pathway.

Finally, in vivo studies confirmed the impact of tRF-AspGTC on IA formation. The research team found that silencing tRF-AspGTC expression significantly inhibited elastase-induced disruption of the elastic lamina and collagen fiber disarray in the murine intracranial arteries, thereby reducing the incidence of intracranial aneurysms and extending the survival of the mice.

Future Perspectives

This study unveils the pathological mechanism by which tsRNAs are involved in IA development, revealing that tRF-AspGTC enhances the stability of galectin-3 by inhibiting its ubiquitination mediated by TRIM29, thereby activating the TLR4/MyD88/NF-κB signaling pathway. The activation of this pathway promotes VSMC phenotypic transformation, MMP9 expression, oxidative stress, and inflammatory responses, ultimately facilitating IA formation. These findings suggest that tRF-AspGTC holds potential as a reliable clinical therapeutic target and diagnostic biomarker in the future.