Sex differences in gene expression patterns associated with the APOE4 allele

Area of Science:

• Neuroscience
• Genetics
• Systems Biology

Background:

• The APOE gene, specifically the APOE4 allele, is a significant risk factor for late-onset Alzheimer's disease (AD).
• Sex differences in AD prevalence and progression suggest underlying biological variations, potentially linked to genetic factors like APOE.
• Apolipoprotein E (ApoE) plays a crucial role in lipid transport and is encoded by the APOE gene, with alleles APOE2, APOE3, and APOE4.

Purpose of the Study:

• To investigate sex-specific gene expression patterns in the brain associated with the APOE4 allele.
• To identify potential molecular mechanisms underlying sex differences in Alzheimer's disease susceptibility and progression.

Main Methods:

• A systems biology approach was employed to analyze brain gene expression data.
• Correlation analysis was used to identify genes with expression patterns similar to APOE in APOE4-positive individuals.
• Gene Ontology (GO) term classification, pathway enrichment, and differential expression analysis were performed.

Main Results:

• A substantial number of genes showed expression patterns correlated with APOE in APOE4-positive individuals, with significantly more identified in females than males.
• APOE4-positive males exhibited more such genes than APOE4-negative controls.
• Significant sex*genotype interactions were observed for the CNTNAP2 gene and brain area*sex*genotype interactions for the PSEN2 gene.

Conclusions:

• The findings suggest that APOE influences gene transcription in a sex-dependent manner, contributing to observed sex differences in Alzheimer's disease.
• The study supports a role for APOE in mediating transcriptional differences relevant to Alzheimer's disease risk and progression in a sex-specific context.