High-throughput in situ mapping of phosphorylated protein complexes across the cell cycle and in response to drugs

• Interactions and posttranslational modifications (PTMs) of proteins orchestrate cellular responses to cytokines, drugs or other agents, but it has been difficult to monitor and characterize these dynamic events at high-throughput. Here, we have established a semi-automated system for large-scale in situ proximity ligation assays (isPLA). The protocol combines isPLA in microtiter wells with automated microscopy and computer-based image analysis whereby specific protein phosphorylations and interactions are digitally recorded in cells, along with measurements of morphological features. We demonstrate how this platform can improve analysis of cellular signaling by investigating TGF-b responsive Smad2 linker phosphorylations and complex formations over time and across millions of individual cells. We depict single cell responses in relation to e.g. local cell crowding and cell cycle progression via measurements of DNA content and nuclear size. Finally, we illustrate the application of the protocol for demonstrating drug effects by screening a library of phosphatase inhibitors. In summary, our approach expands the scope for image-based single cell analyses by combining observations of protein interactions and modifications with morphological details of individual cells at high throughput.

Nyckelord

Biokemi

Biochemistry

Molekylär cellbiologi

Molecular Cellbiology

Molecular Biotechnology

Molekylär bioteknik

Publikations- och innehållstyp

vet (ämneskategori)

ovr (ämneskategori)