Physiological roles of STIM1 and Orai1 homologs and CRAC channels in the genetic model organism Caenorhabditis elegans

Cell Calcium. 2007 Aug;42(2):193-203. doi: 10.1016/j.ceca.2007.02.007. Epub 2007 Mar 21.

Abstract

The nematode Caenorhabditis elegans provides numerous experimental advantages for developing an integrative molecular understanding of physiological processes and has proven to be a valuable model for characterizing Ca(2+) signaling mechanisms. This review will focus on the role of Ca(2+) release activated Ca(2+) (CRAC) channel activity in function of the worm gonad and intestine. Inositol 1,4,5-trisphosphate (IP(3))-dependent oscillatory Ca(2+) signaling regulates contractile activity of the gonad and rhythmic posterior body wall muscle contraction (pBoc) required for ovulation and defecation, respectively. The C. elegans genome contains a single homolog of both STIM1 and Orai1, proteins required for CRAC channel function in mammalian and Drosophila cells. C. elegans STIM-1 and ORAI-1 are coexpressed in the worm gonad and intestine and give rise to robust CRAC channel activity when coexpressed in HEK293 cells. STIM-1 or ORAI-1 knockdown causes complete sterility demonstrating that the genes are essential components of gonad Ca(2+) signaling. Knockdown of either protein dramatically inhibits intestinal cell CRAC channel activity, but surprisingly has no effect on pBoc, intestinal Ca(2+) oscillations or intestinal ER Ca(2+) store homeostasis. CRAC channels thus do not play obligate roles in all IP(3)-dependent signaling processes in C. elegans. Instead, we suggest that CRAC channels carry out highly specialized and cell specific signaling roles and that they may function as a failsafe mechanism to prevent Ca(2+) store depletion under pathophysiological and stress conditions.

Publication types

  • Research Support, N.I.H., Extramural
  • Review

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Caenorhabditis elegans / genetics
  • Caenorhabditis elegans / physiology
  • Caenorhabditis elegans Proteins / chemistry
  • Caenorhabditis elegans Proteins / genetics
  • Caenorhabditis elegans Proteins / physiology*
  • Calcium Channels / chemistry
  • Calcium Channels / genetics
  • Calcium Channels / physiology*
  • Calcium Signaling
  • Gonads / physiology
  • Intestines / physiology
  • Membrane Proteins / chemistry
  • Membrane Proteins / genetics
  • Membrane Proteins / physiology*
  • Models, Genetic
  • Molecular Sequence Data
  • ORAI1 Protein
  • Stromal Interaction Molecule 1

Substances

  • Caenorhabditis elegans Proteins
  • Calcium Channels
  • Membrane Proteins
  • ORAI-1 protein, C elegans
  • ORAI1 Protein
  • Stromal Interaction Molecule 1
  • stim-1 protein, C elegans