Posttranslational protein knockdown coupled to receptor tyrosine kinase activation with phosphoPROTACs

• Published in: Proceedings of the National Academy of Sciences - PNAS 2013-05, Vol.110 (22), p.8942-8947
• Main Authors: Hines, John, Gough, Jonathan D., Corson, Timothy W., Crews, Craig M.
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Analysis of Variance; Animals; Biological Sciences; Cell growth; Cell lines; Chromatography, High Pressure Liquid; Enzyme Activation - physiology; Female; Gene Knockdown Techniques; Growth factor receptors; Humans; Immunoblotting; MCF-7 Cells; Mice; Molecular Sequence Data; Molecular Structure; Molecules; Nerves; PC12 Cells; Peptides; Phosphatidylinositol 3-Kinases - metabolism; Phosphorylation; Protein Processing, Post-Translational - genetics; Protein Processing, Post-Translational - physiology; Proteins; Proteolysis; Rats; Receptor Protein-Tyrosine Kinases - metabolism; Receptor, ErbB-3 - metabolism; Receptor, Fibroblast Growth Factor, Type 2 - genetics; Receptor, Fibroblast Growth Factor, Type 2 - metabolism; Receptor, trkA - antagonists & inhibitors; Receptor, trkA - metabolism; Receptors; Ribonucleic acid; RNA; Signal Transduction - physiology; Streptavidin; Tumors; Viability; Von Hippel-Lindau Tumor Suppressor Protein - metabolism
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.1217206110

Posttranslational knockdown of a specific protein is an attractive approach for examining its function within a system. Here we introduce phospho-dependent proteolysis targeting chimeras (phosphoPROTACs), a method to couple the conditional degradation of targeted proteins to the activation state of particular kinase-signaling pathways. We generated two phosphoPROTACs that couple the tyrosine phosphorylation sequences of either the nerve growth factor receptor, TrkA (tropomyosin receptor kinase A), or the neuregulin receptor, ErbB3 (erythroblastosis oncogene B3), with a peptide ligand for the E3 ubiquitin ligase von Hippel Lindau protein. These phosphoPROTACs recruit either the neurotrophic signaling effector fibroblast growth factor receptor substrate 2α or the survival-promoting phosphatidylinositol-3-kinase, respectively, to be ubiquitinated and degraded upon activation of specific receptor tyrosine kinases and phosphorylation of the phosphoPROTACs. We demonstrate the ability of these phosphoPROTACs to suppress the short- and long-term effects of their respective activating receptor tyrosine kinase pathways both in vitro and in vivo. In addition, we show that activation of phosphoPROTACs is entirely dependent on their kinase-mediated phosphorylation, as phenylalanine-containing null variants are inactive. Furthermore, stimulation of unrelated growth factor receptors does not induce target protein knockdown. Although comparable in efficiency to RNAi, this approach has the added advantage of providing a degree of temporal and dosing control as well as cell-type selectivity unavailable using nucleic acid-based strategies. By varying the autophosphorylation sequence of a phosphoPROTAC, it is conceivable that other receptor tyrosine kinase/effector pairings could be similarly exploited to achieve other biological effects.