My second mini-project was undertaken in the Shäfer lab with Dr Patrick Schäfer and Dr Ruth Eichmann whose research revolves around mutualistic symbioses in adaptive stress signalling, particularly endoplasmic reticulum stress signalling. (More information can be found here)
'Regulation of endoplasmic reticulum stress - A key in the adaption of cells to environmental stress'
'The mutualistic fungus Piriformospora indica colonizes Arabidopsis thaliana roots in a biotrophic manner by suppressing plant immunity. Following this the fungus induces individual cell death through an ER stress-induced caspase-dependent cell death pathway. This project aimed to further demonstrate the molecular principles behind this crucial colonization-associated cell death. Under certain stress conditions eukaryotic cells accumulate a large number of misfolded proteins in their endoplasmic reticulum (ER), this is know as ER-stress. Cells respond by initiating the unfolded protein response (UPR), which can resolve ER homeostasis through an increase in protein folding quality control proteins. However under prolonged or severe ER stress mammalian cells have been shown to induce an apoptosis-like programmed cell death (ER-PCD). Through molecular analyses we demonstrated that P. indica colonization suppresses the splicing of ER stress sensor bZIP60 an Arabidopsis thaliana basic leucine zipper (bZIP) transcription factor for UPR genes, as well as the ER stress response pathway marker binding protein 3 (BiP3), whose suppression is indicative of UPR inhibition. We also demonstrate the absence of altered gene expression for a number of general transcription factors of the Nuclear Factor Y-As (NF-YAs) family during fungal colonization. Additionally to this, we tried to adapt an Arabidopsis root transformation assay to constitutively express a GFP-tagged bZIP60 transcription factor protein. Plant cells were successfully co-transformed with a pRedRoot vector allowing identification of successful chimeric root cells. This assay will help identify the role of bZIP60 in fungal colonization through direct visualisation of P. indica’s interaction with transformed cells.'