Extracellular ATP hydrolysis in Caco-2 human intestinal cell line

Area of Science:

• Gastrointestinal Physiology
• Cellular Biology
• Biochemistry

Background:

• Extracellular nucleotides are key signaling molecules in the gastrointestinal tract.
• Ectonucleotidases hydrolyze extracellular nucleotides, regulating purinergic receptor signaling.
• Caco-2 cells serve as a model for human intestinal epithelial cells.

Purpose of the Study:

• Investigate ectonucleotidase expression, localization, and activity in Caco-2 cells.
• Analyze the regulation of extracellular ATP (eATP) by ATP release and hydrolysis.
• Quantify the dynamic balance between ATP release and consumption.

Main Methods:

• Kinetic characterization of ectoenzymes on intact Caco-2 cells.
• Confirmation of enzyme presence using gels, Western blot, and cytoimmunofluorescence.
• Monitoring of intracellular ATP release and eATP hydrolysis rates.

Main Results:

• Caco-2 cells express and utilize ecto-nucleoside triphosphate diphosphohydrolase-1 and -2, a neutral ecto-phosphatase, and ecto-5'-nucleotidase.
• Mechanical and hypotonic stimuli induce transient intracellular ATP release, increasing eATP.
• EctoATPase activity effectively reduces elevated eATP concentrations.

Conclusions:

• Caco-2 cells actively regulate extracellular ATP metabolism through a dynamic interplay of release and hydrolysis.
• Ectonucleotidases play a critical role in controlling eATP levels at the cell surface.
• A data-driven algorithm can predict ATP release and consumption rates.