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Updated: May 17, 2026
An Electrochemiluminescence-Based Assay for MeCP2 Protein Variants
Published on: May 22, 2020
Phosphorylation of MeCP2 at Ser421 contributes to chronic antidepressant action
Ashley N Hutchinson1, Jay V Deng, Sonia Cohen
1Department of Neurobiology, Duke University Medical Center, Durham, North Carolina 27710, USA.
Abstract:
Although tricyclic antidepressants rapidly activate monoaminergic neurotransmission, these drugs must be administered chronically to alleviate symptoms of depression. This observation suggests that molecular mechanisms downstream of monoamine receptor activation, which include the induction of gene transcription, underlie chronic antidepressant-induced changes in behavior. Here we show that methyl-CpG-binding protein 2 (MeCP2) regulates behavioral responses to chronic antidepressant treatment. Imipramine administration induces phosphorylation of MeCP2 at Ser421 (pMeCP2) selectively in the nucleus accumbens and the lateral habenula, two brain regions important for depressive-like behaviors. To test the role of pMeCP2 in depressive-like behaviors, we used male mice that bear a germ-line mutation knocked into the X-linked Mecp2 locus that changes Ser421 to a nonphosphorylatable Ala residue (S421A). MeCP2 S421A knock-in (KI) mice showed increased immobility in forced-swim and tail-suspension tests compared with their wild-type (WT) littermates. However, immobility of both MeCP2 WT and KI mice in forced swim was reduced by acute administration of imipramine, demonstrating that loss of pMeCP2 does not impair acute pharmacological sensitivity to this drug. After chronic social defeat stress, chronic administration of imipramine significantly improved social interaction in the MeCP2 WT mice. In contrast, the MeCP2 KI mice did not respond to chronic imipramine administration. These data suggest novel roles for pMeCP2 in the sensitivity to stressful stimuli and demonstrate that pMeCP2 is required for the effects of chronic imipramine on depressive-like behaviors induced by chronic social defeat stress.
Insights
Chronic antidepressant treatment requires molecular changes, not just neurotransmitter activation. Methyl-CpG-binding protein 2 (MeCP2) phosphorylation is crucial for antidepressant efficacy, particularly after stress. This highlights MeCP2
Area of Science:
- Neuroscience
- Molecular Biology
- Pharmacology
Background:
- Antidepressants require chronic administration for therapeutic effects, suggesting downstream molecular mechanisms are involved.
- Gene transcription induction is a key molecular event following monoamine receptor activation by antidepressants.
- Methyl-CpG-binding protein 2 (MeCP2) is implicated in regulating gene expression and neuronal function.
Purpose of the Study:
- To investigate the role of MeCP2 phosphorylation in behavioral responses to chronic antidepressant treatment.
- To determine if MeCP2 phosphorylation at Ser421 is necessary for the therapeutic effects of imipramine.
- To explore the involvement of MeCP2 in mediating the impact of chronic social defeat stress on depressive-like behaviors.
Main Methods:
- Utilized male mice with a germ-line mutation in the Mecp2 locus (S421A knock-in) to study non-phosphorylatable MeCP2.
- Administered imipramine acutely and chronically to wild-type (WT) and MeCP2 S421A knock-in (KI) mice.
- Assessed depressive-like behaviors using forced-swim and tail-suspension tests, and social interaction tests after chronic social defeat stress.
Main Results:
- MeCP2 S421A KI mice exhibited increased immobility in behavioral despair tests compared to WT littermates.
- Acute imipramine administration reduced immobility in both WT and KI mice, indicating preserved acute drug sensitivity.
- Chronic imipramine treatment improved social interaction in WT mice but not in MeCP2 S421A KI mice following social defeat stress.
Conclusions:
- Phosphorylation of MeCP2 at Ser421 (pMeCP2) is selectively induced in brain regions relevant to depression by imipramine.
- pMeCP2 is essential for the behavioral effects of chronic imipramine treatment, particularly in response to chronic stress.
- These findings identify pMeCP2 as a critical molecular player in the long-term efficacy of antidepressants and stress resilience.
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