Myocyte enhancer factor-2 and p300 interact to regulate the expression of homeostatic regulator Pumilio in Drosophila

Area of Science:

• Neuroscience
• Molecular Biology
• Genetics

Background:

• Pumilio (Pum) protein is crucial for neuron firing-rate homeostasis, stabilizing neural circuit activity across species.
• Regulation of Pum expression by synaptic excitation in the central nervous system (CNS) is poorly understood.

Purpose of the Study:

• To investigate the molecular mechanisms underlying activity-dependent regulation of Drosophila Pumilio (dpum) gene expression.
• To identify transcription factors and co-regulators involved in dpum promoter activity.

Main Methods:

• Characterization of the Drosophila dpum promoter, identifying myocyte enhancer factor-2 (Mef2)-binding elements.
• Cloning and functional analysis of 12 dmef2 splice variants using a luciferase reporter assay.
• Investigating the role of p300 as a regulator of dpum transcription in response to synaptic excitation.

Main Results:

• All 12 dmef2 splice variants enhanced dpum promoter activity, with exon 10-containing variants showing greater transactivation.
• Synaptic excitation (picrotoxin) did not alter dmef2 transcript levels, suggesting additional regulatory mechanisms.
• p300 binds to dMef2, repressing dpum transactivation; p300 transcript is downregulated by enhanced synaptic excitation, leading to increased dpum transcription via derepression of dMef2.

Conclusions:

• Activity-dependent expression of dpum is regulated by the interplay between p300 and dMef2.
• This interaction provides a novel mechanism for maintaining neuron firing-rate homeostasis.
• Findings advance the understanding of gene regulation in response to neural activity.