METTL7B Mitigates Hypertension and Vascular Remodeling

Hypertension is a major risk factor for cardiovascular diseases. RNA N6-methyladenosine (m⁶A) modification is closely linked to hypertension pathogenesis, but key m⁶A-related factors that regulate blood pressure remain unclear. This study aims to identify these regulators and evaluate their therapeutic potential.

We assessed RNA m⁶A changes and METTL (methyltransferase-like) expression in hypertensive aortas via methylated RNA immunoprecipitation sequencing and RNA sequencing (RNA-seq). Global Mettl7b knockout mice and vascular smooth muscle cell (VSMC)-specific Mettl7b knockin and knockout mice were used to evaluate its in vivo role. Downstream target genes were identified via methylated RNA immunoprecipitation sequencing, enhanced cross-linking and immunoprecipitation sequencing, and RNA-seq. METTL7B activators were screened using molecular docking and surface plasmon resonance and validated in vivo via intraperitoneal injection.

Under hypertensive stress, METTL7B expression positively correlated with global RNA m⁶A content, exhibiting concurrent depletion in VSMCs. In vitro biochemical assays revealed that recombinant METTL7B significantly increased RNA m⁶A levels. Crucially, METTL7B overexpression in METTL3 knockout cells robustly upregulated m⁶A levels, definitively establishing METTL7B as a novel, METTL3-independent RNA m⁶A methyltransferase. Physiologically, VSMC-specific Mettl7b ablation exacerbated angiotensin II-induced hypertensive pathogenesis, structural arterial remodeling, and vascular tone, whereas its overexpression exerted potent vasoprotective effects. Mechanistically, METTL7B recruited HNRNPH1 to catalyze m⁶A deposition at the 3' untranslated region of FILIP1L mRNA, facilitating its maturation. Importantly, the expression of FILIP1L was positively correlated with blood pressure reduction in humans and mice. Elevated FILIP1L downregulated the expression of its binding protein FLNA (Filamin A), reducing F-actin polymerization, attenuating VSMC contractility, and ultimately lowering blood pressure. Furthermore, FILIP1L overexpression reversed the detrimental effects of Mettl7b knockout on hypertension and vascular remodeling, whereas these effects were not rescued by the mutation of FILIP1L's m⁶A site. Elucidating the upstream pathology, we found that stress-induced KLF4 directly bound the METTL7B promoter, transcriptionally repressing its expression. Finally, the Food and Drug Administration-approved drug netarsudil exerted preventive and therapeutic effects on hypertension and vascular remodeling by activating METTL7B; notably, these therapeutic benefits were completely abolished in VSMC-specific Mettl7b knockout mice.

Collectively, our study identifies a novel RNA m⁶A methyltransferase, METTL7B. The METTL7B-HNRNPH1-FILIP1L axis mitigates hypertension by regulating VSMC dedifferentiation and vascular tone. Targeted activation of METTL7B may emerge as a promising strategy for hypertension.