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

Mol Cell. 2017 Mar 2;65(5):885-899.e6. doi: 10.1016/j.molcel.2017.01.020. Epub 2017 Feb 23.


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.

Keywords: ER-PM contact sites; FLNA; PERK; SOCE; STIM1; actin cytoskeleton; actin relocalization; calcium signaling; endoplasmic reticulum; extended-Synaptotagmin 1; plasma membrane; unfolded protein response.

MeSH terms

  • Actin Cytoskeleton / enzymology*
  • Actins / metabolism*
  • Animals
  • Calcium / metabolism
  • Calcium Signaling
  • Cell Membrane / enzymology*
  • Endoplasmic Reticulum / enzymology*
  • Endoplasmic Reticulum Stress*
  • Filamins / genetics
  • Filamins / metabolism*
  • HEK293 Cells
  • HeLa Cells
  • Humans
  • Mice
  • Neoplasm Proteins / metabolism
  • Protein Multimerization
  • Protein Transport
  • RNA Interference
  • Signal Transduction
  • Stromal Interaction Molecule 1 / metabolism
  • Synaptotagmin I / metabolism
  • Time Factors
  • Transfection
  • Unfolded Protein Response
  • eIF-2 Kinase / genetics
  • eIF-2 Kinase / metabolism*


  • Actins
  • FLNA protein, human
  • Filamins
  • FlnA protein, mouse
  • Neoplasm Proteins
  • STIM1 protein, human
  • SYT1 protein, human
  • Stromal Interaction Molecule 1
  • Synaptotagmin I
  • EIF2AK3 protein, human
  • PERK kinase
  • eIF-2 Kinase
  • Calcium