J Neurogastroenterol Motil.
2018 Jan;24(1):128-137. 10.5056/jnm16212.
Regulation of Intracellular Calcium by Endoplasmic Reticulum Proteins in Small Intestinal Interstitial Cells of Cajal
- Affiliations
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- 1Department of Internal Medicine, College of Medicine, Chosun University, Gwangju, Korea.
- 2Department of Medicine, Graduate School, Chosun University, Gwangju, Korea. choiseok@chosun.ac.kr
- 3Department of Physiology, College of Medicine, Chosun University, Gwangju, Korea.
- KMID: 2417280
- DOI: http://doi.org/10.5056/jnm16212
Abstract
- BACKGROUND/AIMS
We investigated the role of representative endoplasmic reticulum proteins, stromal interaction molecule 1 (STIM1), and store-operated calcium entry-associated regulatory factor (SARAF) in pacemaker activity in cultured interstitial cells of Cajal (ICCs) isolated from mouse small intestine.
METHODS
The whole-cell patch clamp technique applied for intracellular calcium ions ([Ca²+]i) analysis with STIM1 or SARAF overexpressed cultured ICCs from mouse small intestine.
RESULTS
In the current-clamping mode, cultured ICCs displayed spontaneous pacemaker potentials. External carbachol exposure produced tonic membrane depolarization in the current-clamp mode, which recovered within a few seconds into normal pacemaker potentials. In STIM1-overexpressing cultured ICCs pacemaker potential frequency was increased, and in SARAF-overexpressing ICCs pacemaker potential frequency was strongly inhibited. The application of gadolinium (a non-selective cation channel inhibitor) or a Ca2+-free solution to understand Orai channel involvement abolished the generation of pacemaker potentials. When recording intracellular Ca²+ concentration with Fluo 3-AM, STIM1-overexpressing ICCs showed an increased number of spontaneous intracellular Ca²+ oscillations. However, SARAF-overexpressing ICCs showed fewer spontaneous intracellular Ca2+ oscillations.
CONCLUSION
Endoplasmic reticulum proteins modulated the frequency of pacemaker activity in ICCs, and levels of STIM1 and SARAF may determine slow wave patterns in the gastrointestinal tract.
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