A scheduler for rhythmic gene expression.

Area of Science:

• Developmental Biology
• Genetics
• Molecular Biology

Background:

• Genetic oscillators are fundamental for precise gene expression timing during development and physiology.
• The C. elegans molting clock serves as a model system to understand how oscillators orchestrate gene expression.
• Understanding the regulatory mechanisms of timed gene expression is crucial for various biological processes.

Purpose of the Study:

• To investigate how genetic oscillators schedule the expression of thousands of genes.
• To identify key regulators and mechanisms controlling rhythmic gene expression.
• To develop a predictive model for chromatin and gene expression dynamics.

Main Methods:

• Single-cell RNA sequencing to analyze gene expression patterns.
• Time-resolved ATAC-seq to map chromatin accessibility dynamics.
• Development of a linear model integrating transcription factor binding data.
• Perturbation experiments (GRH-1/Grainyhead) to validate model predictions.

Main Results:

• Broad peak phase dispersion observed in individual tissues.
• Rhythmic changes in chromatin accessibility at thousands of regulatory elements.
• Identification of nine key transcription factors regulating peak phase and amplitude.
• Demonstration that these factors can generate non-rhythmic activity via destructive interference.
• Accurate prediction of gene expression and chromatin dynamics upon GRH-1 perturbation.

Conclusions:

• Combinatorial, non-cooperative transcription factor binding provides a framework for scheduling complex gene expression patterns.
• The identified regulatory principles are applicable to dynamic biological processes beyond development.
• This study offers insights into the quantitative control of gene expression by transcription factors.