Acetaldehyde-driven mRNA methylation and expression changes in ethanol-metabolizing enzyme genes

Abstract

This study examines how the alcohol metabolite acetaldehyde modulates mRNA methylation and expression of ethanol-metabolizing genes, uncovering its epigenetic role in ethanol metabolism. Using neuron-like (SH-SY5Y) and non-neuronal (SW620) cellular models, we examined the effects of chronic intermittent acetaldehyde (CIA) exposure and subsequent withdrawal (CIA+WD) on global RNA m6A modifications and the methylation and expression of three brain ethanol-metabolizing genes: CAT (catalase), CYP2E1 (cytochrome P450 2E1), and ALDH2 (aldehyde dehydrogenase 2). A 3-week CIA exposure, with or without 24-hour withdrawal, did not significantly alter global m6A methylation levels in either cell line. However, acetaldehyde exposure/withdrawal induced hypermethylation at the mRNA stop codon regions of ALDH2 (CIA: p = 0.002; CIA+WD: p = 0.055) and CAT (CIA: p = 0.077; CIA+WD: p = 0.036) in SH-SY5Y cells, but not in SW620 cells. Furthermore, ALDH2 mRNA expression was significantly upregulated in both cell types following exposure (SH-SY5Y: p = 0.073 [CIA] and 0.00002 [CIA+WD]; SW620: p = 0.0009 [CIA] and 0.00008 [CIA+WD]). In contrast, CYP2E1 mRNA methylation and the expression of CYP2E1 and CAT remained unchanged. These findings highlight the cell-specific epigenetic effects of acetaldehyde, particularly its role in modulating mRNA methylation and expression of ALDH2, a key enzyme in alcohol metabolism.

Keywords: Global m6A RNA methylation; MazF-RT-qPCR; adenocarcinoma cell line SW620; alcohol-metabolizing enzyme genes; chronic intermittent acetaldehyde exposure; mRNA stop codon region m6A modifications; neuroblastoma cell line SH-SY5Y.

Figure 1.

Alcohol metabolizing enzymes and alcohol metabolism in the brain. Alcohol in the brain is mainly metabolized to acetaldehyde by catalase, and acetaldehyde is converted to acetate by aldehyde dehydrogenases (ALDH).

Figure 2.

A 3-week chronic intermittent acetaldehyde (CIA) exposure followed by a 24-hr withdrawal (WD). The figure illustrates the study design, which includes three groups of SH-SY5Y and SW620 cells, respectively: (1) control cells (without acetaldehyde treatment); (2) cells with chronic intermittent acetaldehyde (CIA) exposure; and (3) cell with CIA exposure followed by a 24-hour withdrawal (WD).

Figure 3.

Forward and reverse primers designed for amplifying cDNA sequences around mRNA stop codons of three alcohol-metabolizing enzyme genes and the reference gene ACTB. CAT: the catalase gene; CYP2E1: the cytochrome P450 2E1 gene; ALDH2: the aldehyde dehydrogenase gene; ACTB: the beta-actin gene. Forward and reverse primers are highlighted in magenta, while m6ACA motifs are marked in green. TGA or TAA represents the stop codon of the mRNA.

Figure 4.

Chronic intermittent acetaldehyde (CIA) exposure/withdrawal-induced mRNA methylation and expression changes in the aldehyde dehydrogenase 2 gene (ALDH2). CTL: Control SH-SY5Y or SW620 cells (without acetaldehyde exposure). CIA: a 3-week chronic intermittent acetaldehyde (CIA) exposure. CIA+WD: a 3-week CIA exposure followed by a 24-hr acetaldehyde withdrawal.

Figure 5.

Chronic intermittent acetaldehyde (CIA) exposure/withdrawal-induced mRNA methylation and expression changes in the catalase gene (CAT). CTL:Control SH-SY5Y or SW620 cells (without acetaldehyde exposure). CIA:a 3-week chronic intermittent acetaldehyde (CIA) exposure. CIA+WD:a 3-week CIA exposure followed by a 24-hr acetaldehyde withdrawal.