Dynamic patterns of gene expression match extracellular signals through push-pull regulation

Area of Science:

• Molecular Biology
• Systems Biology
• Cellular Regulation

Background:

• Cells exhibit remarkable ability to adjust gene expression in response to environmental signals.
• Budding yeast, for instance, utilizes at least seven hexose transporter genes, each tuned to specific extracellular glucose concentration ranges.

Purpose of the Study:

• To elucidate the mechanistic basis of how budding yeast matches hexose transporter ([Formula: see text]) gene expression to varying extracellular glucose levels.
• To investigate the role of a novel "push-pull" regulatory network in this process.

Main Methods:

• Time-lapse microscopy
• Microfluidics
• Dynamic glucose perturbation experiments
• Mathematical modeling
• Analysis of transcription factor activity

Main Results:

• A push-pull regulatory mechanism involving Mth1, Std1, Mig1, and Mig2 was identified. Rising glucose weakens repression by Mth1/Std1 while strengthening repression by Mig1/Mig2, and vice-versa for falling glucose.
• The combined activity of these regulators effectively reports extracellular glucose concentrations.
• Specific coupling between [Formula: see text] promoters and these regulators, based on transporter affinity (low, medium, high), enables precise expression matching.
• Experimental rewiring of transcription demonstrated the ability to alter transporter gene response characteristics.

Conclusions:

• The identified push-pull regulation is a key mechanism for matching gene expression to environmental signals like glucose concentration.
• This regulatory strategy allows cells to fine-tune transporter expression for optimal nutrient uptake.
• The principle of push-pull regulation is likely a widespread biological phenomenon with broad implications for gene expression control.