March2 Alleviates Aortic Aneurysm/Dissection by Regulating PKM2 Polymerization.

Background: Aortic aneurysm/dissection (AAD) is a life-threatening disease lacking effective pharmacological treatment. Protein ubiquitination plays a pivotal role in cardiovascular diseases. However, the possible contribution of the E3 ubiquitin ligase March2 (membrane-associated RING finger protein 2) to the cause of AAD remains elusive.

Methods: Integrated single-cell RNA sequencing analysis was conducted in human AAD tissues. Based on the screening results, we generated a mouse line of smooth muscle cell-specific March2 knockout. β-Aminopropionitrile monofumarate was used to establish AAD. Cleavage under targets and tagmentation and cleavage under targets and tagmentation-quantitative polymerase chain reaction were performed to identify possible target genes for histone H3K18 lactylation.

Results: March2 expression was downregulated in aorta from patients with AAD or β-aminopropionitrile monofumarate-induced AAD mice. β-Aminopropionitrile monofumarate-induced AAD was significantly accentuated in March2 global (March2) and vascular smooth muscle cell-specific deletion (March2; Tagln) mice, whereas the AAD pathology was rescued by rAAV9-SM22α-March2 (recombinant adeno-associated virus serotype 9 expressing Flag-tagged March2 under SM22α promoter). March2 interacted with PKM2 (pyruvate kinase M2) to promote K33-linked polyubiquitination. Deficiency of March2 lessened PKM2 dimer-to-tetramer conversion in AAD and overtly exacerbated AAD-induced histone H3K18 lactylation in vascular smooth muscle cells by fostering glucose metabolism reprogramming, thereby promoting p53-driven apoptotic transcriptional response-a hallmark of AAD pathogenesis. TEPP-46, a PKM2-specific activator, pronouncedly alleviated March2 deficiency-deteriorated AAD pathology.

Conclusions: Our findings demonstrated that March2 is a novel endogenous defender that prevents AAD by inhibiting vascular smooth muscle cell apoptosis, suggesting that March2 represents a potential therapeutic target for AAD.