Disordered regions in the IRE1α ER lumenal domain mediate its stress-induced clustering

article Disordered regions in the IRE1α ER lumenal domain mediate its stress-induced clustering published yes Paulina Kettel author Laura Marosits author Elena Spinetti author Michael Rechberger author Caterina Giannini author e3fdddd5-f6e0-11ea-865d-ca99ee6367f4 Philipp Radler author 40136C2A-F248-11E8-B48F-1D18A9856A870000-0001-9198-2182 Isabell Niedermoser author Irmgard Fischer author Gijs A. Versteeg author Martin Loose author 462D4284-F248-11E8-B48F-1D18A9856A870000-0001-7309-9724 Roberto Covino author G. Elif Karagöz author MaLo department JiFr department Conserved signaling cascades monitor protein-folding homeostasis to ensure proper cellular function. One of the evolutionary conserved key players is IRE1, which maintains endoplasmic reticulum (ER) homeostasis through the unfolded protein response (UPR). Upon accumulation of misfolded proteins in the ER, IRE1 forms clusters on the ER membrane to initiate UPR signaling. What regulates IRE1 cluster formation is not fully understood. Here, we show that the ER lumenal domain (LD) of human IRE1α forms biomolecular condensates in vitro. IRE1α LD condensates were stabilized both by binding to unfolded polypeptides as well as by tethering to model membranes, suggesting their role in assembling IRE1α into signaling-competent stable clusters. Molecular dynamics simulations indicated that weak multivalent interactions drive IRE1α LD clustering. Mutagenesis experiments identified disordered regions in IRE1α LD to control its clustering in vitro and in cells. Importantly, dysregulated clustering of IRE1α mutants led to defects in IRE1α signaling. Our results revealed that disordered regions in IRE1α LD control its clustering and suggest their role as a common strategy in regulating protein assembly on membranes. https://research-explorer.ista.ac.at/download/18073/18827/2024_Embo_Kettel.pdf application/pdfno https://creativecommons.org/licenses/by/4.0/ Embo Press2024 eng EMBO Journal 0261-4189 1460-2075 39232130 00130628610000210.1038/s44318-024-00207-0 43204668-4698 Kettel P, Marosits L, Spinetti E, Rechberger M, Giannini C, Radler P, Niedermoser I, Fischer I, Versteeg GA, Loose M, Covino R, Karagöz GE. 2024. Disordered regions in the IRE1α ER lumenal domain mediate its stress-induced clustering. EMBO Journal. 43(20), 4668–4698. P. Kettel et al., “Disordered regions in the IRE1α ER lumenal domain mediate its stress-induced clustering,” EMBO Journal, vol. 43, no. 20. Embo Press, pp. 4668–4698, 2024. Kettel, Paulina, et al. “Disordered Regions in the IRE1α ER Lumenal Domain Mediate Its Stress-Induced Clustering.” EMBO Journal, vol. 43, no. 20, Embo Press, 2024, pp. 4668–98, doi:<a href="https://doi.org/10.1038/s44318-024-00207-0">10.1038/s44318-024-00207-0</a>. Kettel, Paulina, Laura Marosits, Elena Spinetti, Michael Rechberger, Caterina Giannini, Philipp Radler, Isabell Niedermoser, et al. “Disordered Regions in the IRE1α ER Lumenal Domain Mediate Its Stress-Induced Clustering.” EMBO Journal. Embo Press, 2024. <a href="https://doi.org/10.1038/s44318-024-00207-0">https://doi.org/10.1038/s44318-024-00207-0</a>. Kettel P, Marosits L, Spinetti E, et al. Disordered regions in the IRE1α ER lumenal domain mediate its stress-induced clustering. EMBO Journal. 2024;43(20):4668-4698. doi:<a href="https://doi.org/10.1038/s44318-024-00207-0">10.1038/s44318-024-00207-0</a> Kettel, P., Marosits, L., Spinetti, E., Rechberger, M., Giannini, C., Radler, P., … Karagöz, G. E. (2024). Disordered regions in the IRE1α ER lumenal domain mediate its stress-induced clustering. EMBO Journal. Embo Press. <a href="https://doi.org/10.1038/s44318-024-00207-0">https://doi.org/10.1038/s44318-024-00207-0</a> P. Kettel, L. Marosits, E. Spinetti, M. Rechberger, C. Giannini, P. Radler, I. Niedermoser, I. Fischer, G.A. Versteeg, M. Loose, R. Covino, G.E. Karagöz, EMBO Journal 43 (2024) 4668–4698. 180732024-09-15T22:01:42Z2025-09-08T09:22:11Z