The Arabidopsis NPK1-related protein kinases regulate responses triggered by the endoplasmic reticulum stress

The endoplasmic reticulum (ER) is involved in the biosynthesis and folding of secreted and plasma membrane proteins among which there are elements involved in cell wall (CW) deposition. In presence of adverse conditions, unfolded/misfolded proteins accumulate in the ER leading to a condition known as ER stress which is mitigated by the activation of unfolded protein response (UPR). In Arabidopsis, treatment with ER stress inducer tunicamycin (Tm) or with the cellulose biosynthesis inhibitor isoxaben (ISX), causes cellulose reduction triggering the CW damage syndrome, ER stress and the concomitant activation of UPR pathways. The MAP triple kinases (MAP3K) named ARABIDOPSIS NPK1-RELATED PROTEIN KINASES (ANP1-3) are involved in this process since their loss phenocopies ISX and Tm responses and their overexpression confer resistance to prolonged ER stress. ANPs are critical components of intracellular transduction in biotic stress responses and localized in different subcellular compartments in response to CW-derived signals. The aim of this study is providing knowledge of the role of ANPs on ER stress response and cell wall deposition and how different organelles contribute to the perception and adaptation to environmental clues.