TY - JOUR
T1 - NHERF3 is necessary for Escherichia coli heat-stable enterotoxin-induced inhibition of NHE3
T2 - Differences in signaling in mouse small intestine and Caco-2 cells
AU - Chen, Tiane
AU - Lin, Ruxian
AU - Avula, Leela
AU - Sarker, Rafiquel
AU - Yang, Jianbo
AU - Cha, Boyoung
AU - Tse, Chung Ming
AU - McNamara, George
AU - Seidler, Ursula
AU - Waldman, Scott
AU - Snook, Adam
AU - Bijvelds, Marcel J.C.
AU - De Jonge, Hugo R.
AU - Li, Xuhang
AU - Donowitz, Mark
N1 - Funding Information:
This work was supported, in part, by National Institutes of Health National Institute of Diabetes and Digestive and Kidney Diseases Grants R01-DK- 26523, R01-DK-61765, P01-DK-072084, R24-DK-64388, and P30-DK- 89502, The Hopkins Digestive Diseases Basic and Translational Research Core Center, the Hopkins Center for Epithelial Disorders, and the Deutsche Forschungsgemeinschaft (DFG) Sachbihilfe Se460/21-1
Funding Information:
This work was supported, in part, by National Institutes of Health National Institute of Diabetes and Digestive and Kidney Diseases Grants R01-DK-26523, R01-DK-61765, P01-DK-072084, R24-DK-64388, and P30-DK-89502, The Hopkins Digestive Diseases Basic and Translational Research Core Center, the Hopkins Center for Epithelial Disorders, and the Deutsche Forschungsgemeinschaft (DFG) Sachbihilfe Se460/21-1.
Publisher Copyright:
Copyright © 2019 the American Physiological Society.
PY - 2019
Y1 - 2019
N2 - Enterotoxigenic Escherichia coli (ETEC) is a leading cause of childhood death from diarrhea and the leading cause of Traveler's diarrhea. E. coli heat-stable enterotoxin (ST) is a major virulence factor of ETEC and inhibits the brush border Na/H exchanger NHE3 in producing diarrhea. NHE3 regulation involves multiprotein signaling complexes that form on its COOH terminus. In this study, the hypothesis was tested that ST signals via members of the Na/H exchanger regulatory factor (NHERF) family of scaffolding proteins, NHERF2, which had been previously shown to have a role, and now with concentration on a role for NHERF3. Two models were used: mouse small intestine and Caco-2/BBe cells. In both models, ST rapidly increased intracellular cGMP, inhibited NHE3 activity, and caused a quantitatively similar decrease in apical expression of NHE3. The transport effects were NHERF3 and NHERF2 dependent. Also, mutation of the COOH-terminal amino acids of NHERF3 supported that NHERF3-NHERF2 heterodimerization was likely to account for this dual dependence. The ST increase in cGMP in both models was partially dependent on NHERF3. The intracellular signaling pathways by which STcGMP inhibits NHE3 were different in mouse jejunum (activation of cGMP kinase II, cGKII) and Caco-2 cells, which do not express cGKII (elevation of intracellular Ca2+ concentration [Ca2+]i). The ST elevation of [Ca2+]i was from intracellular stores and was dependent on NHERF3-NHERF2. This study shows that intracellular signaling in the same diarrheal model in multiple cell types may be different; this has implications for therapeutic strategies, which often assume that models have similar signaling mechanisms.
AB - Enterotoxigenic Escherichia coli (ETEC) is a leading cause of childhood death from diarrhea and the leading cause of Traveler's diarrhea. E. coli heat-stable enterotoxin (ST) is a major virulence factor of ETEC and inhibits the brush border Na/H exchanger NHE3 in producing diarrhea. NHE3 regulation involves multiprotein signaling complexes that form on its COOH terminus. In this study, the hypothesis was tested that ST signals via members of the Na/H exchanger regulatory factor (NHERF) family of scaffolding proteins, NHERF2, which had been previously shown to have a role, and now with concentration on a role for NHERF3. Two models were used: mouse small intestine and Caco-2/BBe cells. In both models, ST rapidly increased intracellular cGMP, inhibited NHE3 activity, and caused a quantitatively similar decrease in apical expression of NHE3. The transport effects were NHERF3 and NHERF2 dependent. Also, mutation of the COOH-terminal amino acids of NHERF3 supported that NHERF3-NHERF2 heterodimerization was likely to account for this dual dependence. The ST increase in cGMP in both models was partially dependent on NHERF3. The intracellular signaling pathways by which STcGMP inhibits NHE3 were different in mouse jejunum (activation of cGMP kinase II, cGKII) and Caco-2 cells, which do not express cGKII (elevation of intracellular Ca2+ concentration [Ca2+]i). The ST elevation of [Ca2+]i was from intracellular stores and was dependent on NHERF3-NHERF2. This study shows that intracellular signaling in the same diarrheal model in multiple cell types may be different; this has implications for therapeutic strategies, which often assume that models have similar signaling mechanisms.
KW - GC-C
KW - Guanylate cyclase C
KW - Heat-stable E. coli enterotoxin (ST)
KW - Intracellular calcium
KW - NHE3
KW - NHERF2
KW - NHERF3
UR - http://www.scopus.com/inward/record.url?scp=85072717482&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85072717482&partnerID=8YFLogxK
U2 - 10.1152/ajpcell.00351.2018
DO - 10.1152/ajpcell.00351.2018
M3 - Article
C2 - 31365292
AN - SCOPUS:85072717482
SN - 0363-6143
VL - 317
SP - C737-C748
JO - American Journal of Physiology - Cell Physiology
JF - American Journal of Physiology - Cell Physiology
IS - 4
ER -