Quantitative Mass Spectrometry Imaging of Intact Proteins in Tissues

Area of Science:

• Biochemistry
• Analytical Chemistry
• Molecular Biology

Background:

• Quantitative imaging of endogenous proteins is crucial for understanding cellular signaling and metabolism.
• Mass spectrometry imaging (MSI) offers label-free protein mapping but faces quantification challenges due to signal suppression.

Purpose of the Study:

• To develop a quantitative nano-DESI MSI approach for accurate protein mapping in biological tissues.
• To address signal suppression issues in nano-DESI MSI for reliable protein quantification.

Main Methods:

• Incorporation of protein internal standards (IS) into the extraction solvent for nano-DESI MSI.
• Utilizing iFAMS deconvolution software for efficient isolation of protein-specific signals.
• Implementing charge-weighted signal normalization to the IS signal for pixel-wise quantification.

Main Results:

• Accurate quantification of endogenous proteins was achieved in each pixel using the developed method.
• The approach demonstrated successful quantitative imaging of proteins with a single internal standard.
• Validation was performed using immunofluorescence imaging and bulk analysis, confirming the robustness of the method.

Conclusions:

• The quantitative nano-DESI MSI approach enables accurate protein mapping and quantification in complex biological systems.
• This method provides deeper insights into protein function by overcoming previous limitations in MSI quantification.
• The developed technique is a robust tool for MSI experiments requiring precise protein abundance measurements.