Development of a Genetically Encoded Sensor for Arginine.

Area of Science:

• Biochemistry
• Cell Biology
• Medical Diagnostics

Background:

• L-arginine (Arg) is crucial for metabolic and physiological functions, with altered levels linked to diseases.
• Current Arg sensors lack specificity, often cross-reacting with l-ornithine or l-lysine.
• Accurate, real-time Arg measurement is vital for understanding its role in health and disease.

Purpose of the Study:

• To develop and validate a novel sensor, ArgS1, for specific and real-time detection of l-arginine.
• To investigate the role of Arg in MDA-MB-231 breast cancer cells using the ArgS1 sensor.
• To correlate Arg levels with cell viability in the context of arginino-succinate synthetase 1 (ASS1) expression.

Main Methods:

• Development of ArgS1, a sensor exhibiting concentration-dependent fluorescence changes for Arg.
• Characterization of ArgS1's affinity (∼64 μM) and dynamic range (ΔR/R0 of 3).
• Application of ArgS1 to monitor intracellular Arg levels in MDA-MB-231 cells under varying Arg availability and ASS1 expression.

Main Results:

• ArgS1 demonstrated specific and sensitive detection of Arg in both cytoplasm and organelles.
• Arg levels in MDA-MB-231 cells decreased upon extracellular Arg depletion, correlating with reduced cell viability.
• Overexpression of ASS1 led to increased Arg levels and enhanced cell viability.

Conclusions:

• ArgS1 is an effective tool for real-time monitoring of Arg in human cells across physiological and pathological ranges.
• Arg levels significantly influence MDA-MB-231 breast cancer cell viability.
• ArgS1 provides valuable insights for developing Arg-targeted cancer therapies.