A Macromolecular Complex of CFTR, NHERF2, and LPA2 in Intestinal Epithelium and Its Role in the Pathological Process of Secretory Diarrhea

Authors: Zhang, Weiqiang; KONG, SHANSHAN - University Of Tennessee; ZHANG, YANHUI - University Of Tennessee; NAREN, ANJAPARAVANDA - Cedars-Sinai Medical Center

Submitted to: American Society for Cell Biology (ASCB)
Publication Type: Abstract Only
Publication Acceptance Date: 9/26/2022
Publication Date: 1/13/2023
Citation: Zhang, W., Kong, S., Zhang, Y., Naren, A.P. 2023. A Macromolecular Complex of CFTR, NHERF2, and LPA2 in Intestinal Epithelium and Its Role in the Pathological Process of Secretory Diarrhea. American Society for Cell Biology (ASCB). 34(2):1279-1280. https://doi.org/10.1091/mbc.E22-12-0555.
DOI: https://doi.org/10.1091/mbc.E22-12-0555

Interpretive Summary: Diarrhea is the second leading cause of death in children under five years old and the leading cause of malnutrition in this age group. The hyper-activation of a protein called the cystic fibrosis transmembrane conductance regulator (CFTR) in the gastrointestinal tract plays a central role in the pathogenic process of some secretory diarrheas. CFTR forms a protein complex with two other partners, Na+/H+ exchanger regulatory factor 2 (NHERF2) and lysophosphatidic acid receptor 2 (LPA2), at the cell membrane of intestinal epithelial cells. This study aimed to investigate the roles of CFTR-NHERF2-LPA2 complex in fluid homeostasis and inflammatory responses in the gut. Our results showed that CFTR-NHERF2-LPA2 complex plays a critical role in the pathological process of certain secretory diarrheas. In addition to modulating the CFTR-mediated fluid secretion, it also regulates the secretion of a molecule called IL-8 from intestinal epithelial cells, which could contribute to the recruitment and excessive infiltration of immune cells in the gut and cause excessive inflammatory responses and tissue damage. Specific and potent anti-secretory agents can be useful additions to oral rehydration therapy for secretory diarrheas.

Technical Abstract: Background: Diarrhea is the second leading cause of death in children under five years old and the leading cause of malnutrition in this age group. The hyperactivation of the cystic fibrosis transmembrane conductance regulator (CFTR) channels in the gastrointestinal tract plays a central role in the pathogenic process of some secretory diarrheas. CFTR forms a macromolecular complex with Na+/H+ exchanger regulatory factor 2 (NHERF2) and lysophosphatidic acid receptor 2 (LPA2) at the apical plasma membrane of intestinal epithelial cells. This study aimed to investigate the roles of CFTR-NHERF2-LPA2 complex in fluid homeostasis and inflammatory responses in the gut. Methods: (1) Study models: Intestinal epithelial cells (human HT29-CL19A cells, mouse m-ICc12 cells), mouse intestinal epithelial tissues, mouse intestine fluid secretion models. (2) Techniques: immunofluorescence imaging, Western blotting, PCR, proximity ligation assay, ELISA, Ussing chamber, etc. Results: (1) LPA2 is a major LPA receptor in human and mouse intestinal epithelial cells. (2) CFTR complexes with NHERF2 and LPA2 at the plasma membrane of HT29-CL19A cells and m-ICc12 cells. (3) LPA inhibits CFTR channel function through an LPA2-mediated Gi pathway. LPA substantially reduced the cholera toxin (CTX)-induced and CFTR-mediated intestinal fluid secretion in mice. (4) GRI977143 (a specific LPA2 agonist) inhibited the forskolin-induced CFTR channel activity in polarized HT29-CL19A cells and mouse intestinal epithelial tissues. GRI977143 significantly decreased the CTX-induced closed-loop intestinal fluid secretion in mice. (5) Knock-down of LPA2 in HT29-CL19A cells and m-ICc12 cells significantly reduced the gene and protein level of IL-8. GRI977143 also inhibited IL-8 secretion. (6) IL-8 level is decreased in the intestines of LPA2 knockout mice compared to wild type mice. Conclusion: CFTR-NHERF2-LPA2 complex plays a critical role in the pathological process of certain secretory diarrheas. In addition to modulating the CFTR-mediated fluid secretion, it also regulates IL-8 secretion from intestinal epithelial cells which could contribute to excessive inflammatory responses in the gut. Specific and potent anti-secretory agents can be useful additions to oral rehydration therapy for secretory diarrheas. Acknowledgment: Supported in part by ARS project 6066-21000-001-013-R.