Cell-cell coupling and DNA methylation abnormal phenotypes in the after-hours mice

Area of Science:

• Neuroscience
• Epigenetics
• Chronobiology

Background:

• DNA methylation is a key epigenetic regulator of brain functions, including circadian rhythms.
• The precise role of DNA methylation in mediating environmental signals, like light, to the cellular clock's molecular mechanisms remains unclear.
• The after-hours (Afh) mouse model, characterized by a point mutation in the Fbxl3 gene, exhibits a prolonged circadian period.

Purpose of the Study:

• To investigate how the Afh mutation affects DNA methylation and its downstream consequences on the circadian clock.
• To explore the interplay between environmental light signals, epigenetic modifications, and the molecular machinery of the cellular clock in the Afh mouse model.
• To understand the electrophysiological and molecular phenotypes associated with the Afh mutation.

Main Methods:

• In vivo, ex vivo, and in vitro approaches were employed.
• Retinal responses, gene expression, and DNA methylation patterns (using RRBS and pyrosequencing) were analyzed in various brain tissues.
• Primary neuronal cultures with microelectrode array (MEA) technology were utilized for in vitro assessments.

Main Results:

• Mutant Afh neuronal networks showed functional impairments and reduced retinal responses to light.
• Abnormalities in photoreceptive melanopsin (OPN4) expression were observed.
• Alterations in DNA methylation pathways within the retinohypothalamic tract and connections between Rev-Erbα and Fbxl3 were identified.

Conclusions:

• The Afh mutation impacts the epigenetic landscape of circadian biology, affecting neuronal network function and light responsiveness.
• This study contributes to understanding the electrophysiological and molecular responses to external stimuli in the Afh model.
• The findings highlight the significance of DNA methylation as a regulator of neuronal networks and circadian behavior.