Non-cell Autonomous OTX2 Homeoprotein Regulates Visual Cortex Plasticity Through Gadd45b/g

Area of Science:

• Neuroscience
• Developmental Biology
• Epigenetics

Background:

• The transcription factor OTX2 plays a role in brain development and neuronal function.
• Visual cortex plasticity, particularly ocular dominance, is crucial for visual system development and is typically restricted to a critical period.
• Understanding the molecular mechanisms regulating critical period plasticity and its closure is essential.

Purpose of the Study:

• To investigate the role of OTX2 in regulating visual cortex plasticity and critical period timing.
• To identify genes involved in OTX2-dependent visual cortex plasticity.
• To elucidate the molecular mechanisms by which OTX2 influences plasticity.

Main Methods:

• Gene expression analysis in mouse visual cortex at different developmental ages.
• In vivo manipulation of OTX2 levels via cortical infusion and viral expression.
• Analysis of Gadd45b/g expression, MeCP2 foci, and DNA methylation states.

Main Results:

• OTX2 infusion in juvenile mice upregulated Gadd45b/g, while reducing OTX2 in adults caused Gadd45b/g upregulation.
• Viral Gadd45b expression in adult visual cortex induced ocular dominance plasticity.
• Changes in MeCP2 foci and promoter methylation were observed in parvalbumin interneurons, suggesting epigenetic regulation.

Conclusions:

• OTX2 acts as a molecular switch, promoting critical period plasticity in juveniles and suppressing adult plasticity.
• Gadd45b is a key mediator in OTX2's regulation of plasticity, potentially through epigenetic mechanisms.
• This study reveals a novel molecular pathway for controlling the timing and closure of critical periods in the visual cortex.