Regulation of polarised growth in fission yeast by the Stress-Activated Protein Kinase pathway
Item statusRestricted Access
Embargo end date31/07/2022
Rodríguez Rodríguez, Ana Isabel
Cell polarity is a critical feature of cells and refers to the spatial differences in their shape, structure, and function. Most cells are polarised, with structurally and functionally distinct regions. This polarisation facilitates processes such as asymmetric cell division, differentiation and morphogenesis, directional cell migration, nerve impulse transmission, and transport of molecules across tissues. In fission yeast, the stress-activated protein kinase Sty1, homologous of human p38, is a regulator of the major polarity regulator Cdc42. The activation of Sty1 affects the dynamics of the Cdc42 polarity module, by inducing its dispersal from the sites of growth. However, the link between cell stress and cell polarity is still poorly understood. To identify the targets of Sty1 that are part of the novel polarity regulation pathway, I used a phosphoproteomics approach. I optimised a new triple SILAC protocol to analyse the changes in the whole phosphoproteome of the cells upon Sty1 activation. The implemented protocol allows the identification of up to 50,000 total phosphopeptides per experiment. Interestingly, many of the identified phosphosites that show a significant Sty1-dependent change in phosphorylation belong to proteins that are important for polarity establishment and maintenance. However, the role of Sty1 in controlling cell polarity seems not to be restricted to the regulation of Cdc42: my results suggest that the Sty1 might be a regulator of cell polarity at multiple levels, by controlling the dynamics of proteins that are involved in diverse polarity establishment and maintenance pathways, including the MOR pathway component Sog2, and the eisosome proteins Eis1 and Pil1.