Transcriptional Regulation of MECP2E1-E2 Isoforms and BDNF by Metformin and Simvastatin through Analyzing Nascent RNA Synthesis in a Human Brain Cell Line

Abstract

Methyl CpG binding protein 2 (MeCP2) is the main DNA methyl-binding protein in the brain that binds to 5-methylcytosine and 5-hydroxymethyl cytosine. MECP2 gene mutations are the main origin of Rett Syndrome (RTT), a neurodevelopmental disorder in young females. The disease has no existing cure, however, metabolic drugs such as metformin and statins have recently emerged as potential therapeutic candidates. In addition, induced MECP2-BDNF homeostasis regulation has been suggested as a therapy avenue. Here, we analyzed nascent RNA synthesis versus steady state total cellular RNA to study the transcriptional effects of metformin (an anti-diabetic drug) on MECP2 isoforms (E1 and E2) and BNDF in a human brain cell line. Additionally, we investigated the impact of simvastatin (a cholesterol lowering drug) on transcriptional regulation of MECP2E1/E2-BDNF. Metformin was capable of post-transcriptionally inducing BDNF and/or MECP2E1, while transcriptionally inhibiting MECP2E2. In contrast simvastatin significantly inhibited BDNF transcription without significantly impacting MECP2E2 transcripts. Further analysis of ribosomal RNA transcripts confirmed that the drug neither individually nor in combination affected these fundamentally important transcripts. Experimental analysis was completed in conditions of the presence or absence of serum starvation that showed minimal impact for serum deprival, although significant inhibition of steady state MECP2E1 by simvastatin was only detected in non-serum starved cells. Taken together, our results suggest that metformin controls MECP2E1/E2-BDNF transcriptionally and/or post-transcriptionally, and that simvastatin is a potent transcriptional inhibitor of BDNF. The transcriptional effect of these drugs on MECP2E1/E2-BDNF were not additive under these tested conditions, however, either drug may have potential application for related disorders.

MeCP2 Is an Epigenetic Factor That Links DNA Methylation with Brain Metabolism

“…In this regard, MeCP2 binding to methylated DNA resulted in a reduced rate of RNA polymerase II at the transcription start sites, which may lead to suppressed transcriptional initiation [ 100 ]. Of note, MeCP2 homeostasis regulation is through a regulatory network that involves BDNF-MeCP2 regulation [ 101 , 102 , 103 , 104 , 105 ]. The regulatory link of BDNF-MeCP2, in part, involves MeCP2 phosphorylation at specific serine residues that contribute in response to certain drugs [ 106 , 107 ].…”

“…Overall, MeCP2 harbors a robust role in brain function and progression towards neural developmental milestones, at the beginning of neuronal differentiation, and in mature neurons. Furthermore, MeCP2 is differentially expressed in a region-dependent manner and is cell type-specific-dependent in both human and murine brain/brain cells [ 42 , 43 , 44 , 45 , 46 , 47 , 73 , 101 , 102 , 104 , 114 ]. Given that MeCP2 participates in regulating dynamic gene expression, researchers have highlighted its vital involvement in neurobehavioral abnormalities that are linked to many complications such as metabolic impairments.…”

“…Although a direct link between MeCP2 and brain metabolism remains to be fully explored, emerging studies that focus on DNA methylation/MeCP2 and metabolism in the context of neuronal pathologies provide insight about this relationship. Accordingly, commonly used drugs that are administered in patients to control glucose and cholesterol metabolism are subjects of study for MeCP2-associated disorders such as Rett Syndrome and other diseases of the brain such as brain tumors [ 18 , 20 , 104 , 232 , 233 , 234 , 235 ].…”

New insights on the potential anti‐epileptic effect of metformin: Mechanistic pathway

“…Different studies revealed that metformin improves expression and BDNF levels in experimental cerebral ischaemia in animal models via an AMPK‐dependent pathway 113,114 . Likewise, metformin improves age‐mediated neurocognitive impairment through the activation of BDNF/TrkB signalling 115 . Metformin has been shown to enhance neurogenesis and spatial memory formation in adult mice through increased phosphorylation of atypical protein kinase C (aPKC), activation of CREB binding protein (CBP) and activation of BDNF signalling 115 .…”

The Chromatin Structure at the MECP2 Gene and In Silico Prediction of Potential Coding and Non-Coding MECP2 Splice Variants

“…The reason for this might be a longer period of developmental plasticity in humans, suggesting that MeCP2 might alter the expression of the genes important for neuronal development [ 30 , 39 ]. MECP2 is regulated both transcriptionally and post-transcriptionally [ 27 , 37 , 40 ].…”