Transcriptional Inhibition of the Mecp2 Promoter by MeCP2E1 and MeCP2E2 Isoforms Suggests Negative Auto-Regulatory Feedback that can be Moderated by Metformin

AbstractThe epigenetic factor Methyl-CpG-Binding Protein 2 (MeCP2) is a nuclear protein that binds methylated DNA molecules (both 5-methylcytosine and 5-hydroxymethylcytosine) and controls gene transcription. MeCP2 is an important transcription factor that acts in a dose-dependent manner in the brain; thus, its optimal expression level in brain cells is important. As such, its deregulated expression, as well as gain- or loss-of-function mutation, lead to impaired neurodevelopment, and  compromised structure and function of brain cells, particularly in neurons. Studies from others and us have characterized two well-recognized MeCP2 isoforms: MeCP2E1 and MeCP2E2. We have reported that in Daoy medulloblastoma brain cells, MeCP2E2 overexpression leads to MeCP2E1 protein degradation. Whether MeCP2 isoforms regulate theMecp2 promoter regulatory elements remains unexplored. We previously showed that in Daoy cells, metformin (an anti-diabetic drug) inducesMECP2E1 transcripts. However, possible impact of metformin on theMecp2 promoter activity was not studied. Here, we generated stably transduced Daoy cell reporters to express EGFP driven by theMecp2 promoter. Transduced cells were sorted into four EGFP-expressing groups (R4-to-R7) with different intensities of EGFP expression. Our results confirm that theMecp2 promoter is active in Daoy cells, and that overexpression of either isoform inhibits theMecp2 promoter activity, as detected by flow cytometry and luciferase reporter assays. ...
Source: Journal of Molecular Neuroscience - Category: Neuroscience Source Type: research