Sprouty is a negative regulator of RAS–ERK signalling, which controls cell growth and division. Due to its known functions as a tumour suppressor in various cancers, sprouty activity needs to be tightly controlled to prevent disease. In this work, Carolina Locatelli, Luke Chamberlain and co-workers (Locatelli et al., 2020) investigate the mechanisms and outcomes of the poorly studied S-acylation of sprouty-2 in its C-terminal cysteine-rich domain. They show that sprouty-2 is S-acylated by both the low-selectivity/high-activity enzymes zDHHC3 and zDHHC7 and the high-selectivity/low-activity zDHHC17, which specifically targets the C265 and C268 residues. Additionally, S-acylation by all three enzymes increases sprouty-2 stability. S-acylation also requires non-cysteine residues, namely D214, K223 and, to a lesser extent, N211. A mutant carrying alanine substitutions of these three residues (sprouty-2 NDK) displays reduced stability, and both stability and S-acylation of the NDK mutant are reduced upon co-expression of zDHHC17 or zDHHC7, suggesting that these residues play a general role in promoting sprouty-2 S-acylation. Lastly, the authors demonstrate that the sprouty-2 NDK or C265A/C268A mutants lose plasma membrane localisation, highlighting the requirement of S-acylation in successful sprouty-2 trafficking. Collectively, these results identify a novel mechanism regulating sprouty-2 levels and localisation with potential therapeutic implications for the treatment of cancer.
