Imaging phosphorylated peptide distribution in human lens by MALDI MS

Area of Science:

• Biochemistry
• Proteomics
• Analytical Chemistry

Background:

• Phosphorylation is crucial for cellular functions like growth, division, and signal transduction.
• Analyzing phosphorylated peptides via imaging mass spectrometry is challenging due to low ionization efficiency.

Purpose of the Study:

• To develop a method for on-tissue analysis of phosphorylated peptides.
• To map the region-specific phosphoproteome distribution in human lenses.

Main Methods:

• Utilized a graphene oxide-immobilized enzyme reactor for in situ digestion.
• Applied dephosphorylation treatment to enhance signal intensity of phosphorylated peptides.
• Employed imaging mass spectrometry for phosphoproteome mapping.

Main Results:

• Successfully mapped the phosphoproteome of a human lens.
• Phosphorylated peptides were predominantly found in the nucleus of healthy lenses.
• Cataractous lenses showed dominant localization of phosphorylated peptides in the outer cortex.

Conclusions:

• The developed method enables improved on-tissue analysis of phosphorylated peptides.
• Significant differences in phosphoproteome distribution exist between healthy and cataractous human lenses.
• This approach provides insights into lens pathophysiology and potential biomarkers.