Single Cell-Type Spatial Proteomics Uncovers Regional Heterogeneity of Astrocytes

Area of Science:

• Neuroscience
• Proteomics
• Cell Biology

Background:

• Astrocytes are crucial glial cells in the central nervous system (CNS), supporting brain function through diverse subpopulations.
• Understanding astrocyte heterogeneity is vital, but mRNA levels from sequencing don't always reflect protein function due to post-transcriptional regulation.

Purpose of the Study:

• To develop and apply a spatial proteomics platform for direct protein profiling of astrocytes in intact brain tissue.
• To identify region-specific astrocyte proteomic signatures and novel protein markers in the mouse brain.

Main Methods:

• Utilized Microscoop Mint, a microscopy-guided spatial proteomics platform.
• Integrated subcellular, region-specific sample preparation with LC-MS/MS mass spectrometry.
• Analyzed astrocyte protein profiles in paraformaldehyde-fixed, OCT-embedded mouse cerebral cortex and hippocampus.

Main Results:

• Uncovered distinct region-associated astrocyte proteomic signatures in the cerebral cortex and hippocampus.
• Identified MINK1 and PLEKHB1 as novel candidate protein markers with preferential expression in hippocampal and cortical astrocytes, respectively.
• Demonstrated the platform's capability for high-precision, unbiased spatial proteomic discovery at subcellular resolution.

Conclusions:

• Spatial proteomics provides essential protein-level insights into astrocyte heterogeneity, complementing transcriptomic data.
• The developed platform enables precise mapping of astrocyte molecular diversity and functional specialization.
• Identified potential region-specific markers (MINK1, PLEKHB1) for distinguishing astrocyte populations in different brain regions.