The BDNF Val66Met variant affects gene expression through miR-146b

Area of Science:

• Neurogenetics
• Molecular Psychiatry
• Gene Expression Regulation

Background:

• Genetic variation, particularly single nucleotide polymorphisms (SNPs), significantly influences gene expression and susceptibility to complex diseases.
• The BDNF Val66Met SNP is linked to various psychiatric disorders, including depression, anxiety, and schizophrenia.
• Mechanisms by which trans-acting variants modulate gene expression and disease risk remain largely unclear.

Purpose of the Study:

• To investigate the impact of the BDNF Val66Met SNP on microRNA (miRNA) expression in the hippocampus.
• To elucidate the downstream effects of SNP-induced miRNA dysregulation on target genes.
• To understand the role of trans effects of common variants on miRNA-mediated gene expression in complex traits.

Main Methods:

• Global microRNA expression profiling in the hippocampus of humanized BDNF Val66Met knock-in mice.
• Quantitative analysis of specific miRNA (miR-146b) and downstream target gene (Per1, Npas4, Irak1) expression.
• In vitro validation of molecular interactions.

Main Results:

• The BDNF Val66Met SNP dysregulates at least one microRNA, specifically reducing miR-146b levels.
• Reduced miR-146b correlates with increased Per1 and Npas4 mRNA, and Irak1 protein levels.
• These molecular changes are observed in vitro and mirrored in the hippocampus of hBDNF(Met/Met) mice.

Conclusions:

• Common variants, like BDNF Val66Met, exert trans effects influencing miRNA-mediated gene expression.
• Dysregulation of miR-146b by the BDNF Val66Met SNP is a key mechanism affecting downstream gene targets.
• These findings contribute to understanding the genetic architecture of complex disorders and traits through miRNA pathways.