Role of the store-operated calcium entry proteins Stim1 and Orai1 in muscarinic cholinergic receptor-stimulated calcium oscillations in human embryonic kidney cells

J Physiol. 2007 Mar 15;579(Pt 3):679-89. doi: 10.1113/jphysiol.2006.125641. Epub 2007 Jan 11.


We have investigated the nature of the Ca2+ entry supporting [Ca2+]i oscillations in human embryonic kidney (HEK293) cells by examining the roles of recently described store-operated Ca2+ entry proteins, Stim1 and Orai1. Knockdown of Stim1 by RNA interference (RNAi) reduced the frequency of [Ca2+]i oscillations in response to a low concentration of methacholine to the level seen in the absence of external Ca2+. However, knockdown of Stim1 did not block oscillations in canomical transient receptor potential 3 channel (TRPC3)-expressing cells and did not affect Ca2+ entry in response to arachidonic acid. The effects of knockdown of Stim1 could be reversed by inhibiting Ca2+ extrusion with a high concentration of Gd3+, or by rescuing the knockdown by overexpression of Stim1. Similarly, knockdown of Orai1 abrogated [Ca2+]i oscillations, and this was reversed by use of high concentrations of Gd3+; however, knockdown of Orai1 did not affect arachidonic acid-activated entry. RNAi targeting 34 members of the transient receptor potential (TRP) channel superfamily did not reveal a role for any of these channel proteins in store-operated Ca2+ entry in HEK293 cells. These findings indicate that the Ca2+ entry supporting [Ca2+]i oscillations in HEK293 cells depends upon the Ca2+ sensor, Stim1, and calcium release-activated Ca2+ channel protein, Orai1, and provide further support for our conclusion that it is the store-operated mechanism that plays the major role in this pathway.

Publication types

  • Research Support, N.I.H., Intramural

MeSH terms

  • Bacterial Proteins / genetics
  • Calcium / metabolism
  • Calcium Channels / genetics
  • Calcium Channels / physiology*
  • Calcium Signaling / drug effects
  • Calcium Signaling / physiology*
  • Cells, Cultured
  • Enzyme Inhibitors / pharmacology
  • Humans
  • Kidney / cytology*
  • Luminescent Proteins / genetics
  • Membrane Proteins / genetics
  • Membrane Proteins / physiology*
  • Methacholine Chloride / pharmacology
  • Muscarinic Agonists / pharmacology
  • Neoplasm Proteins / genetics
  • Neoplasm Proteins / physiology*
  • ORAI1 Protein
  • RNA Interference
  • Receptors, Muscarinic / genetics
  • Receptors, Muscarinic / physiology*
  • Stromal Interaction Molecule 1
  • Thapsigargin / pharmacology
  • Transfection


  • Bacterial Proteins
  • Calcium Channels
  • Enzyme Inhibitors
  • Luminescent Proteins
  • Membrane Proteins
  • Muscarinic Agonists
  • Neoplasm Proteins
  • ORAI1 Protein
  • ORAI1 protein, human
  • Receptors, Muscarinic
  • STIM1 protein, human
  • Stromal Interaction Molecule 1
  • yellow fluorescent protein, Bacteria
  • Methacholine Chloride
  • Thapsigargin
  • Calcium