fr
Article scientifique
Anglais

STIM1 knockdown reveals that store-operated Ca2+ channels located close to sarco/endoplasmic Ca2+ ATPases (SERCA) pumps silently refill the endoplasmic reticulum

Publié dansThe Journal of biological chemistry, vol. 282, no. 15, p. 11456-11464
Date de publication2007
Résumé

Stromal interaction molecule (STIM) proteins are putative ER Ca2+ sensors that recruit and activate store-operated Ca2+ (SOC) channels at the plasma membrane, a process triggered by the Ca2+ depletion of the endoplasmic reticulum (ER). To test whether STIM1 is required for ER refilling, we used RNA interference and measured Ca2+ signals in the cytosol, the ER, and the mitochondria of HeLa cells. Knockdown of STIM1 (mRNA levels, 73%) reduced SOC entry by 73% when sarco/endoplasmic Ca2+ ATPases (SERCA) were inhibited by thapsigargin but did not prevent Ca2+ stores refilling when cells were stimulated by physiological agonists. Stores could be fully refilled by increasing the external Ca2+ concentration above physiological values, but no cytosolic Ca2+ signals were detected during store refilling even at very high Ca2+ concentrations. [Ca2+](ER) measurements revealed that the basal activity of SERCA was not affected in STIM1 knockdown cells and that [Ca2+](ER) levels were restored within 2 min in physiological saline following store depletion. Mitochondrial inhibitors reduced ER refilling in wild-type but not in STIM1 knockdown cells, indicating that ER refilling does not require functional mitochondria at low STIM1 levels. Our data show that ER refilling is largely preserved at reduced STIM1 levels, despite a drastic reduction of store-operated Ca2+ entry, because Ca2+ ions are directly transferred from SOC channels to SERCA. These findings are consistent with the formation of microdomains containing not only SOC channels on the plasma membrane and STIM proteins on the ER but also SERCA pumps and mitochondria to refill the ER without perturbing the cytosol.

Mots-clés
  • Endoplasmic Reticulum
  • Hela Cells
  • Homeostasis
  • Humans
  • Membrane Proteins
  • Mitochondria
  • Neoplasm Proteins
  • RNA
  • Small Interfering
  • Sarcoplasmic Reticulum Calcium-Transporting ATPases
Citation (format ISO)
JOUSSET, Hélène, FRIEDEN, Maud, DEMAUREX, Nicolas. STIM1 knockdown reveals that store-operated Ca2+ channels located close to sarco/endoplasmic Ca2+ ATPases (SERCA) pumps silently refill the endoplasmic reticulum. In: The Journal of biological chemistry, 2007, vol. 282, n° 15, p. 11456–11464. doi: 10.1074/jbc.M609551200
Fichiers principaux (1)
Article (Published version)
accessLevelRestricted
Identifiants
ISSN du journal0021-9258
514vues
67téléchargements

Informations techniques

Création21.11.2008 16:18:00
Première validation21.11.2008 16:18:00
Heure de mise à jour14.03.2023 14:59:22
Changement de statut14.03.2023 14:59:22
Dernière indexation18.01.2024 07:25:34
All rights reserved by Archive ouverte UNIGE and the University of GenevaunigeBlack