WTAP affects intracranial aneurysm progression by regulating m6A methylation modification

Intracranial aneurysm (IA) is a type of cerebrovascular disease that mainly occurs in the circle of Willis. Abnormalities in RNA methylation at the N6-methyladenosine (m6A) site have been associated with numerous types of human diseases. WTAP recruits the m6A methyltransferase complexes to the mRNA targets, and its expression is positively correlated with m6A methylation levels. This research aimed to explore the potential mechanisms of m6A methylation in IA. A selective arterial ligation method was used to establish an IA rat model; thereafter, the m6A methylation level and m6A methylation-related genes were determined in blood and circle of Willis samples using a commercial kit and real-time quantitative PCR, respectively. Subsequently, rat brain microvascular endothelial cells (rBMVECs) were treated with TNF-α, and the expression of m6A methylation-related genes within the cells were assessed. Lastly, the effects of WTAP on TNF-α-induced rBMVECs were further investigated through in vitro experiments. In result, the m6A RNA methylation level evidently declined in the blood and circle of Willis’ samples of the IA rats, as compared to the corresponding samples from the control rats (P < 0.05). Compared to the results in the control rats/cells, WTAP expression was significantly downregulated, whereas ALKBH1 expression was evidently upregulated in the blood and circle of Willis samples of the TNF-α-induced rBMVECs of IA rats. Consequently, TNF-α-induced rBMVECs and rBMVECs with WTAP overexpression were successfully established. TNF-α inhibited the viability of the rBMVECs, promoted apoptosis, and significantly upregulated cleaved-caspase3 and downregulated WTAP expression. In contrast, WTAP overexpression significantly reversed these changes caused by TNF-α (P < 0.05). In conclusion, WTAP overexpression may modulate the growth of TNF-α-induced rBMVECs by enhancing WTAP expression and its m6A methylation.