Macrophage ALDH2 (Aldehyde Dehydrogenase 2) Stabilizing Rac2 Is Required for Efferocytosis Internalization and Reduction of Atherosclerosis Development

Abstract

BACKGROUND: Clinical studies show that the most common single-point mutation in humans, ALDH2 (aldehyde dehydrogenase 2) rs671 mutation, is a risk factor for the development and poor prognosis of atherosclerotic cardiovascular diseases, but the underlying mechanism remains unclear. Apoptotic cells are phagocytosed and eliminated by macrophage efferocytosis during atherosclerosis, and enhancement of arterial macrophage efferocytosis reduces atherosclerosis development. METHODS: Plaque areas, necrotic core size, apoptosis, and efferocytosis in aortic lesions were investigated in APOE −/− mice with bone marrow transplanted from APOE − /− ALDH2 − /− and APOE − /− mice. RNA-seq, proteomics, and immunoprecipitation experiments were used to screen and validate signaling pathways affected by ALDH2. Efferocytosis and protein levels were verified in human macrophages from wild-type and rs671 mutation populations. RESULTS: We found that transplanting bone marrow from APOE − /− ALDH2 − /− to APOE − /− mice significantly increased atherosclerosis plaques compared with transplanting bone marrow from APOE − /− to APOE − /− mice. In addition to defective efferocytosis in plaques of APOE − /− mice bone marrow transplanted from APOE − /− ALDH2 − /− mice in vivo, macrophages from ALDH2 − /− mice also showed significantly impaired efferocytotic activity in vitro. Subsequent RNA-seq, proteomics, and immunoprecipitation experiments showed that wild-type ALDH2 directly interacted with Rac2 and attenuated its degradation due to decreasing the K48-linked polyubiquitination of lysine 123 in Rac2, whereas the rs671 mutant markedly destabilized Rac2. Furthermore, Rac2 played a more crucial role than other Rho GTPases in the internalization process in which Rac2 was up-regulated, activated, and clustered into dots. Overexpression of wild-type ALDH2 in ALDH2 − /− macrophages, rather than the rs671 mutant, rescued Rac2 degradation and defective efferocytosis. More importantly, ALDH2 rs671 in human macrophages dampened the apoptotic cells induced upregulation of Rac2 and subsequent efferocytosis. CONCLUSIONS: Our study has uncovered a pivotal role of the ALDH2-Rac2 axis in mediating efferocytosis during atherosclerosis, highlighting a potential therapeutic strategy in cardiovascular diseases, especially for ALDH2 rs671 mutation carriers.

Exercise Mitigates Endothelial Pyroptosis and Atherosclerosis by Downregulating NEAT1 Through N6-Methyladenosine Modifications

“…24 Additionally, estrogen has an inhibitory effect on diet-induced atherosclerosis formation. [25][26][27] Therefore, to accelerate lesion formation, only male animals were used in our study. To establish atherosclerotic lesions, 6-to 8-week-old male ApoE −/− , ApoE −/− NEAT1 −/− , and ApoE −/− METTL14 +/− mice were fed a high-fat diet (HFD) containing 10% lard, 4% milk powder, 2% cholesterol, and 0.5% sodium cholate for 12 weeks.…”

Applying multi-omics techniques to the discovery of biomarkers for acute aortic dissection

“…However, inactivating mutations in ALDH2 (called ALDH2*2 or rs671 mutants) are risk factors for the development and poor prognosis of atherosclerotic cardiovascular disease. By using RNA-seq, proteomics, and immunoprecipitation experiments, we later discovered and verified Rac2 as its downstream target, demonstrating the crucial function of the ALDH2-Rac2 axis in mediating cytokinesis during atherosclerosis ( 170 ). As a result, many genes are present in the body as a “double-edged sword,” and even in diseases that are linked to specific mutations, they can have opposing effects.…”

RAC-king up Efferocytosis in Atherosclerotic Plaques With Aldehyde Dehydrogenase 2 Deficiency

“…Possibly, detailed knowledge on ALDH2 downstream targets might positively alter this gloomy outlook. Nevertheless, Zhang et al 17 have elegantly elucidated yet another piece of the complicated biological puzzle of dead cell removal in atherosclerosis.…”

“…18 The role of RAC1-dependent actin dynamics has been studied before in foam cell macrophages, yet it was unknown if and how RAC2 was involved. Zhang et al 17 now show that ALDH2 protects RAC2 from ubiquitin-mediated degradation and hence improves efferocytosis. With loss- and gain-of-function experiments, the authors confirmed that the ALDH2-RAC2 axis was crucial for efferocytosis.…”

“…In this issue, Zhang et al 17 actually uncovered a causal role of ALDH2 (aldehyde dehydrogenase 2) in dead cell uptake by plaque macrophages, while aiming to understand the molecular pathways explaining the association of the rs671 SNP (single nucleotide polymorphism) in ALDH2 with acute coronary syndromes. In vivo, ALDH2 (ALDH2 − /− ) bone marrow transplantation resulted in aggravated atherosclerosis, and defective efferocytosis in ALDH2 −/− /ApoE −/− double knockout mice.…”