Phosphorylation of STIM1 at ERK/CDK sites is dispensable for cell migration and ER partitioning in mitosis

Cell Calcium. 2021 Dec:100:102496. doi: 10.1016/j.ceca.2021.102496. Epub 2021 Oct 23.

Abstract

Store-operated Ca2+ entry (SOCE) is a ubiquitous Ca2+ influx pathway required for multiple physiological functions including cell motility. SOCE is triggered in response to depletion of intracellular Ca2+ stores following the activation of the endoplasmic reticulum (ER) Ca2+ sensor STIM1, which recruits the plasma membrane (PM) Ca2+ channel Orai1 at ER-PM junctions. STIM1 is phosphorylated dynamically, and this phosphorylation has been implicated in several processes including SOCE inactivation during M-phase, maximal SOCE activation, ER segregation during mitosis, and cell migration. Human STIM1 has 10 Ser/Thr residues in its cytosolic domain that match the ERK/CDK consensus phosphorylation. We recently generated a mouse knock-in line where wild-type STIM1 was replaced by a non-phosphorylatable STIM1 with all ten S/Ts mutated to Ala (STIM1-10A). Here, we generate mouse embryonic fibroblasts (MEF) from the STIM1-10A mouse line and a control MEF line (WT) that express wild-type STIM1 from a congenic mouse strain. These lines offer a unique model to address the role of STIM1 phosphorylation at endogenous expression levels in contrast to previous studies that relied mostly on overexpression. We show that STIM1 phosphorylation at ERK/CDK sites is not required for SOCE activation, cell migration, or ER partitioning during mitosis. These results rule out STIM1 phosphorylation as a regulator of SOCE, migration, and ER distribution in mitosis.

Keywords: Calcium Signaling; Cell migration; Endoplasmic reticulum; Mitosis; STIM1; Store-operated calcium entry.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Calcium Signaling
  • Calcium* / metabolism
  • Cell Movement
  • Endoplasmic Reticulum / metabolism
  • Fibroblasts / metabolism
  • Membrane Proteins* / genetics
  • Membrane Proteins* / metabolism
  • Mice
  • Mitosis
  • ORAI1 Protein / metabolism
  • Phosphorylation
  • Stromal Interaction Molecule 1 / genetics
  • Stromal Interaction Molecule 1 / metabolism

Substances

  • Membrane Proteins
  • ORAI1 Protein
  • Stim1 protein, mouse
  • Stromal Interaction Molecule 1
  • Calcium