Creb1-Mecp2-(m)CpG complex transactivates postnatal murine neuronal glucose transporter isoform 3 expression

Area of Science:

• Neuroscience
• Molecular Biology
• Epigenetics

Background:

• Neuronal glucose transporter isoform 3 (Glut3) expression is developmentally regulated in mice, peaking at postnatal day 14.
• DNA methylation patterns in the 5'-flanking region of the glut3 gene are associated with developmental changes.

Purpose of the Study:

• To investigate the role of CpG island methylation in the 5'-flanking region of the murine glut3 gene.
• To elucidate the molecular mechanisms by which methylation influences glut3 gene transcription during neuronal development.

Main Methods:

• Methylation-specific PCR and bisulfite sequencing to analyze CpG island methylation.
• Luciferase reporter assays in HT22 hippocampal neurons to assess transcriptional activity.
• Chromatin immunoprecipitation (ChIP) and co-immunoprecipitation (Co-IP) to study protein-DNA and protein-protein interactions.

Main Results:

• CpG island methylation of the glut3 gene increases with postnatal age and inhibits transcription in reporter assays.
• Methyl-CpG binding protein 2 (Mecp2) binds to methylated CpGs in the glut3 gene.
• Creb1 recruitment to the glut3 promoter facilitates Mecp2 binding and enhances glut3 transcription, overcoming methylation-induced suppression.

Conclusions:

• Glut3 is a methylation-sensitive neuronal gene.
• The interaction between Mecp2 and Creb1 at the glut3 promoter facilitates gene transactivation, enabling developmental expression despite DNA methylation.
• This mechanism provides an escape from CpG-induced gene suppression, promoting neuronal Glut3 expression.