Cell-specific exon methylation and CTCF binding in neurons regulate calcium ion channel splicing and function

Area of Science:

• Neuroscience
• Molecular Biology
• Epigenetics

Background:

• Cell-specific alternative splicing regulates cell functions and is implicated in disease.
• The mechanisms controlling alternative splicing are often linked to RNA splicing factors.
• In sensory neurons, alternative splicing of the Cacna1b gene affects opioid sensitivity.

Purpose of the Study:

• To investigate the regulatory mechanisms of cell-specific alternative splicing of the Cacna1b gene in sensory neurons.
• To understand how DNA methylation influences alternative splicing and CTCF binding.
• To explore the role of this splicing in normal conditions and following nerve injury.

Main Methods:

• Utilized a DRG-derived cell line to study DNA hypomethylation and CTCF binding.
• Performed in vivo studies in mice to examine exon methylation and splicing in nociceptors.
• Investigated changes in methylation and splicing following nerve injury.

Main Results:

• Cell and exon-specific DNA hypomethylation enables CTCF binding, which controls alternative splicing.
• In vivo, hypomethylation of an alternative exon in nociceptors leads to CaV2.2 channel isoforms with higher opioid sensitivity.
• Nerve injury increases exon methylation and disrupts splicing patterns.

Conclusions:

• Defined the molecular mechanisms of cell-specific alternative splicing for a functionally validated exon in sensory neurons.
• Identified DNA hypomethylation and CTCF binding as key regulators of Cacna1b alternative splicing.
• Revealed that disrupted splicing due to increased methylation after nerve injury presents a potential therapeutic target for chronic pain.