Endoplasmic reticulum (ER) stress and oxidative stress have recently been linked to the pathogenesis of inflammatory bowel diseases. Under physiological conditions, intestinal epithelial cells are exposed to ER and oxidative stress affecting the cellular ionic homeostasis. However, these altered ion flux ‘signatures’ during these stress conditions are poorly characterized. We investigated the kinetics of K⁺, Ca²⁺ and H⁺ ion fluxes during ER and oxidative stress in a colonic epithelial cell line LS174T using a non-invasive microelectrode ion flux estimation technique. ER and oxidative stress were induced by cell exposure to tunicamycin (TM) and copper ascorbate (CuAsc), respectively, from 1 to 24 h. Dramatic K⁺ efflux was observed following acute ER stress with peak K⁺ efflux being
306 and
1387 nmolm
^-2s
^-1 for 10 and 50μgml
^-1, respectively (p<0.01). TM-dependent Ca²⁺ uptake was more prolonged with peak values of 085 and 268 nmolm
^-2s
^-1 for 10 and 50 mgml^-1 TM, respectively (p<0.02). Ion homeostasis was also affected by the duration of ER stress. Increased duration of TM treatment from 0 to 18 h led to increases in both K⁺ efflux and Ca²⁺ uptake. While K⁺ changes were significantly higher at each time point tested, Ca²⁺ uptake was significantly higher only after prolonged treatment (18 h). CuAsc also led to an increased K⁺ efflux and Ca²⁺ uptake. Functional assays to investigate the effect of inhibiting K⁺ efflux with tetraethylammonium resulted in increased cell viability. We conclude that ER/oxidative stress in colonic epithelial cells cause dramatic K⁺, Ca²⁺ and H⁺ ion flux changes, which may predispose this lineage to poor stress recovery reminiscent of that seen in inflammatory bowel diseases.

Item Type:	Refereed Article
Keywords:	ER stress, inflammatory bowel disease, ion flux, oxidative stress, colonic epithelial cells
Research Division:	Medical and Health Sciences
Research Group:	Medical Biochemistry and Metabolomics
Research Field:	Medical Biochemistry and Metabolomics not elsewhere classified
Objective Division:	Expanding Knowledge
Objective Group:	Expanding Knowledge
Objective Field:	Expanding Knowledge in the Medical and Health Sciences
Author:	Shabala, L (Dr Lana Shabala)
Author:	Walker, EJ (Mrs Emma Walker)
Author:	Eklund, A (Miss Anne Eklund)
Author:	Randall-Demllo, S (Mr Sarron Randall-Demllo)
Author:	Shabala, S (Professor Sergey Shabala)
Author:	Guven, N (Dr Nuri Guven)
Author:	Cook, AL (Dr Tony Cook)
Author:	Eri, RD (Associate Professor Raj Eri)
ID Code:	81846
Year Published:	2013 (online first 2012)
Web of Science® Times Cited:	6
Deposited By:	Pharmacy
Deposited On:	2013-01-09
Last Modified:	2017-11-06
Downloads:	0