Single-cell NF-kappaB dynamics reveal digital activation and analogue information processing

Area of Science:

• Cellular Biology
• Immunology
• Systems Biology

Background:

• Cell-to-cell communication is vital for multicellular organisms, particularly in the mammalian immune response.
• Cells must interpret diverse signaling molecule concentrations, forming spatiotemporal gradients.
• Tumor necrosis factor-alpha (TNF-alpha) is a key signaling molecule in cellular communication.

Purpose of the Study:

• To investigate single mammalian cell responses to varying TNF-alpha concentrations.
• To understand how cells relay information via nuclear factor kappa-light-chain-enhancer of activated B cells (NF-kappaB) signaling.
• To characterize the digital and analog aspects of NF-kappaB activation at the single-cell level.

Main Methods:

• High-throughput microfluidic cell culture and fluorescence microscopy.
• Quantitative gene expression analysis.
• Stochastic mathematical modeling of NF-kappaB signaling dynamics.

Main Results:

• NF-kappaB activation exhibits single-cell heterogeneity, acting as a digital process with dose-dependent cell activation.
• Cells encode analog parameters, including NF-kappaB peak intensity, response time, and oscillation number.
• A stochastic model accurately reproduced observed digital and analog dynamics across various conditions.

Conclusions:

• Single-cell resolution reveals a digital nature of TNF-alpha-induced NF-kappaB signaling, challenging population-level observations.
• Analog parameters fine-tune cellular responses, adding complexity to signal interpretation.
• The developed model offers a broadly applicable framework for understanding TNF-alpha signaling in diverse cell types.