The MLH1 -93 promoter variant influences gene expression

Area of Science:

• Genetics
• Molecular Biology
• Cancer Research

Background:

• The MLH1 gene plays a crucial role in DNA mismatch repair.
• Aberrant MLH1 methylation is implicated in various cancers, including endometrial and colorectal types.
• A single nucleotide polymorphism (SNP) at position -93 of the MLH1 promoter has been associated with altered gene methylation.

Purpose of the Study:

• To investigate the functional impact of the MLH1 -93 SNP on MLH1 gene expression.
• To determine if the -93 SNP influences the binding of nuclear proteins to the MLH1 promoter.

Main Methods:

• Luciferase reporter assay was employed to quantify gene expression driven by different MLH1 promoter variants.
• Electrophoretic mobility shift assay (EMSA) was used to assess the binding affinity of nuclear proteins to probes containing the -93A and -93G alleles.

Main Results:

• Luciferase activity was significantly lower for the -93A allele compared to the -93G allele, indicating reduced gene expression.
• EMSA demonstrated differential binding affinities of nuclear proteins to the -93A and -93G probes, suggesting altered transcription factor interactions.

Conclusions:

• The MLH1 -93 SNP influences MLH1 gene expression.
• This effect is mediated by the SNP's impact on the binding of nuclear proteins to the MLH1 promoter region.
• The findings provide a molecular mechanism linking the -93 SNP to altered MLH1 expression and potentially cancer development.