Multivariate proteomic profiling identifies novel accessory proteins of coated vesicles

Area of Science:

• Cell Biology
• Proteomics
• Molecular Biology

Background:

• Characterizing transport vesicles, particularly clathrin-coated vesicles (CCVs), presents significant challenges in proteomics.
• Advances in mass spectrometry have improved proteomic analysis, yet comprehensive vesicle profiling remains difficult.

Purpose of the Study:

• To develop and validate a multivariate proteomics approach for detailed analysis of CCVs.
• To identify and characterize proteins associated with CCVs, including novel components.
• To investigate the role of CCVs in cellular processes like mitosis and endocytosis.

Main Methods:

• Utilized siRNA knockdown of coat components and varied fractionation protocols to enrich CCV fractions.
• Employed stable isotope labeling of amino acids in cell culture (SILAC)-based quantitative mass spectrometry for comparative analysis.
• Integrated 10 datasets using principal component analysis for "profiling" cluster analysis.

Main Results:

• Successfully identified 136 CCV-associated proteins, including 36 novel proteins.
• Achieved identification of >93% of established CCV coat proteins with >91% correct intracellular or endocytic localization.
• Identified and characterized tepsin, the first accessory protein for AP-4 vesicles, and explained TACC3 sequestration in mitotic defects.

Conclusions:

• The developed multivariate proteomics approach is effective for comprehensive CCV characterization.
• This method enhances the identification and localization of CCV proteins and can be applied to other coated vesicle types.
• The findings provide insights into CCV function, mitotic regulation, and potential therapeutic targets.