posted on 2021-08-26, 21:03authored byBocheng Yin, Laura R. Caggiano, Rung-Chi Li, Emily McGowan, Jeffrey W. Holmes, Sarah E. Ewald
Tissue
microenvironment properties like blood flow, extracellular
matrix, or proximity to immune-infiltrate are important regulators
of cell biology. However, methods to study regional protein expression
in the native tissue environment are limited. To address this need,
we developed a novel approach to visualize, purify, and measure proteins in situ using automated spatially targeted optical microproteomics
(AutoSTOMP). Here, we report custom codes to specify regions of heterogeneity
in a tissue section and UV-biotinylate proteins within those regions.
We have developed liquid chromatography–mass spectrometry (LC–MS)/MS-compatible
biochemistry to purify those proteins and label-free quantification
methodology to determine protein enrichment in target cell types or
structures relative to nontarget regions in the same sample. These
tools were applied to (a) identify inflammatory proteins expressed
by CD68+ macrophages in rat cardiac infarcts and (b) characterize
inflammatory proteins enriched in IgG4+ lesions in human
esophageal tissues. These data indicate that AutoSTOMP is a flexible
approach to determine regional protein expression in situ on a range of primary tissues and clinical biopsies where current
tools and sample availability are limited.