The N⁶-methyladenosine modification posttranscriptionally regulates hepatic UGT2B7 expression

Area of Science:

• Biochemistry
• Molecular Biology
• Pharmacology

Background:

• UDP-glucuronosyltransferases (UGTs) are crucial enzymes for metabolizing endogenous and exogenous compounds.
• N⁶-methyladenosine (m⁶A) is a key RNA modification influencing gene expression.
• The role of m⁶A in regulating hepatic UGT expression, particularly UGT2B7, remains largely unexplored.

Purpose of the Study:

• To investigate the impact of m⁶A modification on hepatic UGT expression.
• To elucidate the specific mechanisms by which m⁶A affects UGT2B7 regulation.
• To identify potential therapeutic targets for modulating UGT2B7 activity.

Main Methods:

• HepaRG and Huh-7 cell lines were used to study UGT expression.
• RNA methylation inhibitors (3-deazaadenosine) and demethylase inhibitors (entacapone) were employed.
• Gene knockdown of key m⁶A regulators (METTL3, METTL14, FTO, ALKBH5) was performed.
• Methylated RNA immunoprecipitation, actinomycin D assays, and luciferase reporter assays were utilized.

Main Results:

• Inhibition of RNA methylation increased UGT mRNA levels, notably UGT2B7.
• m⁶A modification was found on UGT2B7 mRNA, primarily in the 5'UTR.
• Knockdown of m⁶A 'writers' (METTL3/14) increased UGT2B7, while knockdown of 'erasers' (FTO/ALKBH5) decreased it, indicating m⁶A downregulates UGT2B7.
• FTO knockdown reduced UGT2B7 transactivity via decreased HNF4α expression.
• Entacapone, an FTO inhibitor, decreased HNF4α and UGT2B7 expression.

Conclusions:

• RNA methylation, specifically m⁶A modification, is a critical posttranscriptional regulator of hepatic UGT2B7 expression.
• m⁶A modification downregulates UGT2B7 expression through mechanisms involving mRNA stability and transactivity modulation.
• These findings highlight the potential of targeting RNA methylation pathways for controlling drug metabolism.