Single-cell methylomes identify neuronal subtypes and regulatory elements in mammalian cortex.

Area of Science:

• Neuroscience
• Epigenetics
• Genomics

Background:

• The mammalian brain exhibits remarkable neuronal diversity, but comprehensive single-cell characterization remains challenging.
• DNA methylation serves as a stable epigenetic marker crucial for cell type identification and regulatory element definition.

Purpose of the Study:

• To develop and apply single-nucleus epigenomic assays for identifying and characterizing diverse neuronal populations.
• To investigate cell type-specific DNA methylation patterns and their role in neuronal diversity.

Main Methods:

• Generation of over 6000 single-nucleus methylomes from mouse and human frontal cortex.
• Analysis of CG and non-CG methylation distributions across neuronal subtypes.
• Identification of differentially methylated regulatory elements.

Main Results:

• Discovery of 16 mouse and 21 human neuronal subpopulations based on methylation signatures.
• Identification of a specific layer 6 excitatory neuron subtype and a unique human parvalbumin-expressing inhibitory neuron subtype.
• Observation of greater cross-species conservation of regulatory elements in inhibitory neurons compared to excitatory neurons.

Conclusions:

• Single-nucleus methylomes provide an expanded atlas of brain cell types.
• Epigenomic signatures reveal regulatory elements driving conserved brain cell diversity.
• This approach enhances our understanding of neuronal heterogeneity and evolution.