ALKBH5 as a therapeutic target for hypertension: Inhibiting vascular smooth muscle cell phenotypic switch via the TEAD3/PDZK1 axis.

Hypertension is a chronic disease accompanied by vascular remodeling. As an m6A demethylase, ALKBH5 is implicated in cardiovascular diseases. Herein, we demonstrated that ALKBH5 expression was upregulated in the aortic tissues of spontaneously hypertensive rats (SHR), with predominant localization in vascular smooth muscle cells (VSMCs). To define ALKBH5 function, we generated an SM22α-driven, VSMC-specific Alkbh5-knockdown AAV9 vector and administered a single tail-vein injection (11 × 10¹² v.g./rat) to 4-week-old male SHRs. Alkbh5 knockdown markedly lowered arterial pressure in SHRs, ameliorated left ventricular remodeling, attenuated aortic media thickening and extracellular matrix deposition, and suppressed the contractile-to-synthetic/proliferative phenotypic switch of VSMCs. Primary thoracic aortic VSMCs were isolated from 16-week-old SHRs and Wistar-Kyoto (WKY) rats, with Alkbh5 knockdown achieved via adenoviral transduction. Separately, primary human aortic smooth muscle cells were pretreated with 1 μM angiotensin II for 24 h prior to adenoviral infection. In vitro assays further verified that ALKBH5 knockdown suppressed proliferation and the contractile-to-synthetic/proliferative phenotypic switch in VSMCs in hypertensive context. Subsequent mechanistic studies revealed that ALKBH5 knockdown enhanced the stability of TEAD3 mRNA by increasing its m6A modification; the upregulated TEAD3 could directly bind to the PDZK1 promoter and promote its transcription. Moreover, PDZK1 knockdown reversed the inhibitory effect of ALKBH5 knockdown on the abnormal proliferation of VSMCs. In conclusion, ALKBH5 knockdown inhibits the abnormal phenotypic switch of VSMCs through the TEAD3/PDZK1 axis, thereby alleviating vascular remodeling caused by hypertension. These findings suggest that ALKBH5 may serve as a potential therapeutic target for hypertension.