(Phospho-)proteomics analysis of fission yeast cells during mating and cell-cell fusion

In fission yeast Schizosaccharomyces pombe, sexual reproduction is triggered by the absence of nitrogen (N), and relies on crosstalk between multiple signaling pathways, with the inactivation of the TORC1 complex playing a critical role. This process is further elicited by pheromone signaling between the two mating types, P (h+) and M (h-), through GPCR activation of a Ras-MAPK cascade. Once partners are selected, cell projections (shmoos) extend to bring the cells together. Upon pairing, actin fusion foci at the contact site, concentrate hydrolases to digest the cell wall and ensure coordinated fusion. While several kinases and phosphatases are known to promote sexual differentiation and cell fusion, their specific substrates remain largely unknown. To address those questions, we have developed methods to synchronize cell populations during mating and cell-cell fusion and used time course phospho-proteomics to identify dynamic phosphorylation changes. The aim was to uncover the phosphorylation events driving differentiation and morphogenetic changes necessary for cell projection and cell fusion.