ALDH2 deficiency aggravates vascular injury-induced restenosis by enhancing vascular smooth muscle cell proliferation through SLC38A2-mediated upregulation of glutamine uptake

Background and aims

Vascular injury-induced restenosis is an important cause of poor long-term prognosis in patients with coronary artery disease (CAD). Although aldehyde dehydrogenase 2 (ALDH2) deficiency has been linked to poor outcomes in CAD patients, the precise mechanisms through which ALDH2 influences vascular injury-induced restenosis remain elusive. Herein, we attempted to explore the role of ALDH2 in modulating vascular smooth muscle cell (VSMC) proliferation and vascular injury-induced restenosis.

Methods and results

Immunofluorescence and immunoblotting revealed that ALDH2 expression was significantly decreased in VSMCs in human stenotic coronary segments and injured mouse femoral and carotid arteries. Global ALDH2 knockout and VSMC-specific ALDH2 knockout exacerbated injury-induced neointima formation, whereas VSMC-specific ALDH2 overexpression reduced neointima formation. Endothelial cell (EC)-specific ALDH2 knockout had little effect on injury-induced neointima formation. Mechanistic studies revealed that ALDH2 deficiency facilitated VSMC proliferation by upregulating the expression of the glutamine transporter SLC38A2, which is a novel ALDH2 target gene. Further bioinformatics analysis, luciferase assays, and ChIP–qPCR revealed that ALDH2 deficiency increased SLC38A2 expression via activating transcription factor 4 (ATF4) and that ATF4 knockdown largely reversed the ability of ALDH2 deficiency to promote VSMC proliferation. Moreover, ALDH2 deficiency promoted the accumulation of 4-HNE adducted proteins, thereby activating ATF4, which subsequently increased SLC28A2 transcriptional activity in VSMCs. Importantly, downregulation of SLC38A2 by adeno-associated virus serotype 2 (AAV2) shRNA or by the inhibitor MeAIB has promising therapeutic potential in limiting VSMC proliferation and neointima formation. Finally, we demonstrated that VSMC proliferation was aggravated and that neointima formation occurred in ALDH2^E506k mutant mice.

Conclusion

Our study elucidates a novel mechanism through which ALDH2 deficiency aggravates neointimal formation by enhancing VSMC proliferation through an increase in glutamine uptake, suggesting a promising translational strategy for the prevention of vascular injury-induced restenosis.