title: Parallel visualization of multiple protein complexes in individual cells in tumor tissue.
abstract: Cellular functions are regulated and executed by complex protein interaction networks. Accordingly, it is essential to understand the interplay between proteins in determining the activity status of signaling cascades. New methods are therefore required to provide information on different protein interaction events at the single cell level in heterogeneous cell populations such as in tissue sections. Here, we describe a multiplex proximity ligation assay for simultaneous visualization of multiple protein complexes in situ. The assay is an enhancement of the original proximity ligation assay, and it is based on using proximity probes labeled with unique tag sequences that can be used to read out which probes, from a pool of probes, have bound a certain protein complex. Using this approach, it is possible to gain information on the constituents of different protein complexes, the subcellular location of the complexes, and how the balance between different complex constituents can change between normal and malignant cells, for example. As a proof of concept, we used the assay to simultaneously visualize multiple protein complexes involving EGFR, HER2, and HER3 homo- and heterodimers on a single-cell level in breast cancer tissue sections. The ability to study several protein complex formations concurrently at single cell resolution could be of great potential for a systems understanding, paving the way for improved disease diagnostics and possibilities for drug development.
authors: Department of Immunology, Genetics and Pathology, Science for Life Laboratory, Rudbeck Laboratory, University of Uppsala, Uppsala, Sweden. leuchowius@wehi.edu.au
authors: Karl-Johan
authors: KJ
authors: Leuchowius
authors: Carl-Magnus
authors: CM
authors: Clausson
authors: Karin
authors: K
authors: Grannas
authors: Yücel
authors: Y
authors: Erbilgin
authors: Johan
authors: J
authors: Botling
authors: Agata
authors: A
authors: Zieba
authors: Ulf
authors: U
authors: Landegren
authors: Ola
authors: O
authors: Söderberg
mesh_terms: D000818:Animals; D001706:Biopsy; D001943:Breast Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000648:ultrastructure*; D042783:Endothelial Cells / Q000378:metabolism / Q000473:pathology; D066246:ErbB Receptors / Q000235:genetics* / Q000378:metabolism; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D018796:Immunoconjugates / Q000737:chemistry; D057054:Molecular Imaging / Q000379:methods*; D015335:Molecular Probes / Q000737:chemistry; D011485:Protein Binding; D025941:Protein Interaction Mapping; D055503:Protein Multimerization; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000235:genetics* / Q000378:metabolism; D020893:Receptor, ErbB-3 / Q000235:genetics* / Q000378:metabolism; D015398:Signal Transduction; D059010:Single-Cell Analysis; D013552:Swine
chemical_list: D066246:ErbB Receptors; D018796:Immunoconjugates; D015335:Molecular Probes; D018719:Erb-b2 Receptor Tyrosine Kinases; D020893:Receptor, ErbB-3; C512478:EGFR protein, human; C508053:ERBB2 protein, human; C581292:ERBB3 protein, human