High-Throughput Mapping of a Dynamic Signaling Network in Mammalian Cells

Signaling pathways transmit information through protein interaction networks that are dynamically regulated by complex extracellular cues. We developed LUMIER (for luminescence-based mammalian interactome mapping), an automated high-throughput technology, to map protein-protein interaction networks systematically in mammalian cells and applied it to the transforming growth factor–β (TGFβ) pathway. Analysis using self-organizing maps and k -means clustering identified links of the TGFβ pathway to the p21-activated kinase (PAK) network, to the polarity complex, and to Occludin, a structural component of tight junctions. We show that Occludin regulates TGFβ type I receptor localization for efficient TGFβ-dependent dissolution of tight junctions during epithelial-to-mesenchymal transitions.