The ER Stress Sensor PERK Coordinates ER-Plasma Membrane Contact Site Formation through Interaction with Filamin-A and F-Actin Remodeling

• DOI: 10.1016/j.molcel.2017.01.020
• Publication Date: 2017-02-23T19:25:07Z
• Authors: Alexander R. van ...; Francesca Giordano; Sarah Gerlo; Inmaculada Segura; Sofie Van Eygen; Geert Molenberghs; Susana Rocha; Audrey Houcine; Rita Derua; Tom Verfaillie; Jeroen Vangindertael; Herlinde De Keers...; Etienne Waelkens; Jan Tavernier; Johan Hofkens; Wim Annaert; Peter Carmeliet; Afshin Samali; Hideaki Mizuno; Patrizia Agostinis
• Keywords: 0301 basic medicine; Filamins; Cell Membrane; Endoplasmic Reticulum; Endoplasmic Reticulum Stress; Actins; Neoplasm Proteins; Actin Cytoskeleton; Mice; Protein Transport; 03 medical and health sciences; HEK293 Cells; Synaptotagmin I; Animals; Humans; Calcium; RNA Interference; Calcium Signaling; Stromal Interaction Molecule 1; Protein Multimerization; HeLa Cells; Signal Transduction

Loss of ER Ca2+ homeostasis triggers endoplasmic reticulum (ER) stress and drives ER-PM contact sites formation in order to refill ER-luminal Ca2+. Recent studies suggest that the ER stress sensor and mediator of the unfolded protein response (UPR) PERK regulates intracellular Ca2+ fluxes, but the mechanisms remain elusive. Here, using proximity-dependent biotin identification (BioID), we identified the actin-binding protein Filamin A (FLNA) as a key PERK interactor. Cells lacking PERK accumulate F-actin at the cell edges and display reduced ER-PM contacts. Following ER-Ca2+ store depletion, the PERK-FLNA interaction drives the expansion of ER-PM juxtapositions by regulating F-actin-assisted relocation of the ER-associated tethering proteins Stromal Interaction Molecule 1 (STIM1) and Extended Synaptotagmin-1 (E-Syt1) to the PM. Cytosolic Ca2+ elevation elicits rapid and UPR-independent PERK dimerization, which enforces PERK-FLNA-mediated ER-PM juxtapositions. Collectively, our data unravel an unprecedented role of PERK in the regulation of ER-PM appositions through the modulation of the actin cytoskeleton.