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Balasubramaniam A, Tedbury PR, Mwangi SM, Liu Y, Li G, Merlin D, Gracz AD, He P, Sarafianos SG, Srinivasan S. SARS-CoV-2 Induces Epithelial-Enteric Neuronal Crosstalk Stimulating VIP Release. Biomolecules 2023; 13:207. [PMID: 36830577 PMCID: PMC9953368 DOI: 10.3390/biom13020207] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Revised: 01/06/2023] [Accepted: 01/13/2023] [Indexed: 01/22/2023] Open
Abstract
BACKGROUND Diarrhea is present in up to 30-50% of patients with COVID-19. The mechanism of SARS-CoV-2-induced diarrhea remains unclear. We hypothesized that enterocyte-enteric neuron interactions were important in SARS-CoV-2-induced diarrhea. SARS-CoV-2 induces endoplasmic reticulum (ER) stress in enterocytes causing the release of damage associated molecular patterns (DAMPs). The DAMPs then stimulate the release of enteric neurotransmitters that disrupt gut electrolyte homeostasis. METHODS Primary mouse enteric neurons (EN) were exposed to a conditioned medium from ACE2-expressing Caco-2 colonic epithelial cells infected with SARS-CoV-2 or treated with tunicamycin (ER stress inducer). Vasoactive intestinal peptides (VIP) expression and secretion by EN were assessed by RT-PCR and ELISA, respectively. Membrane expression of NHE3 was determined by surface biotinylation. RESULTS SARS-CoV-2 infection led to increased expression of BiP/GRP78, a marker and key regulator for ER stress in Caco-2 cells. Infected cells secreted the DAMP protein, heat shock protein 70 (HSP70), into the culture media, as revealed by proteomic and Western analyses. The expression of VIP mRNA in EN was up-regulated after treatment with a conditioned medium of SARS-CoV-2-infected Caco-2 cells. CD91, a receptor for HSP70, is abundantly expressed in the cultured mouse EN. Tunicamycin, an inducer of ER stress, also induced the release of HSP70 and Xbp1s, mimicking SARS-CoV-2 infection. Co-treatment of Caco-2 with tunicamycin (apical) and VIP (basolateral) induced a synergistic decrease in membrane expression of Na+/H+ exchanger (NHE3), an important transporter that mediates intestinal Na+/fluid absorption. CONCLUSIONS Our findings demonstrate that SARS-CoV-2 enterocyte infection leads to ER stress and the release of DAMPs that up-regulates the expression and release of VIP by EN. VIP in turn inhibits fluid absorption through the downregulation of brush-border membrane expression of NHE3 in enterocytes. These data highlight the role of epithelial-enteric neuronal crosstalk in COVID-19-related diarrhea.
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Affiliation(s)
- Arun Balasubramaniam
- Division of Digestive Diseases, Department of Medicine, Emory University, Atlanta, GA 30322, USA
- VA Medical Center Atlanta, Decatur, GA 30033, USA
| | | | - Simon M. Mwangi
- Division of Digestive Diseases, Department of Medicine, Emory University, Atlanta, GA 30322, USA
- VA Medical Center Atlanta, Decatur, GA 30033, USA
| | - Yunshan Liu
- Division of Digestive Diseases, Department of Medicine, Emory University, Atlanta, GA 30322, USA
- VA Medical Center Atlanta, Decatur, GA 30033, USA
| | - Ge Li
- Division of Digestive Diseases, Department of Medicine, Emory University, Atlanta, GA 30322, USA
- VA Medical Center Atlanta, Decatur, GA 30033, USA
| | - Didier Merlin
- VA Medical Center Atlanta, Decatur, GA 30033, USA
- Institute for Biomedical Sciences, Center for Inflammation, Immunity and Infection, Digestive Disease Research Group, Georgia State University, Atlanta, GA 30302, USA
| | - Adam D. Gracz
- Division of Digestive Diseases, Department of Medicine, Emory University, Atlanta, GA 30322, USA
| | - Peijian He
- Division of Digestive Diseases, Department of Medicine, Emory University, Atlanta, GA 30322, USA
| | | | - Shanthi Srinivasan
- Division of Digestive Diseases, Department of Medicine, Emory University, Atlanta, GA 30322, USA
- VA Medical Center Atlanta, Decatur, GA 30033, USA
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Ran L, Yan T, Zhang Y, Niu Z, Kan Z, Song Z. The recycling regulation of sodium-hydrogen exchanger isoform 3(NHE3) in epithelial cells. Cell Cycle 2021; 20:2565-2582. [PMID: 34822321 DOI: 10.1080/15384101.2021.2005274] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
Abstract
As the main exchanger of electroneutral NaCl absorption, sodium-hydrogen exchanger isoform 3 (NHE3) circulates in the epithelial brush border (BB) and intracellular compartments in a multi-protein complex. The size of the NHE3 complex changes during rapid regulation events. Recycling regulation of NHE3 in epithelial cells can be roughly divided into three stages. First, when stimulated by Ca2+, cGMP, and cAMP-dependent signaling pathways, NHE3 is converted from an immobile complex found at the apical microvilli (MV) into an easily internalized and mobile form that relocates to a compartment near the base of the MV. Second, NHE3 is internalized by clathrin and albumin-dependent pathways into cytoplasmic endosomal compartments, where the complex is reprocessed and reassembled. Finally, NHE3 is translocated from the recycling endosomes (REs) to the apex of epithelial cells, a process that can be stimulated by an increase in sodium-glucose cotransporter 1 (SGLT1) activity, epidermal growth factor receptor (EGFR) signaling, Ca2+ signaling, and binding to βPix and SH3 and multiple ankyrin repeat domains 2 (Shank2) proteins. This review describes the molecular steps and protein interactions involved in the recycling movement of NHE3 from the apex of epithelial cells, into vesicles, where it is reprocessed and reassembled, and returned to its original location on the plasma membrane, where it exerts its physiological function.
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Affiliation(s)
- Ling Ran
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Southwest University, Rongchang, China
| | - Tao Yan
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Xinjiang Agricultural University, Urumqi, China
| | - Yiling Zhang
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Southwest University, Rongchang, China
| | - Zheng Niu
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Southwest University, Rongchang, China
| | - Zifei Kan
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Southwest University, Rongchang, China
| | - Zhenhui Song
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Southwest University, Rongchang, China
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Control of Intestinal Epithelial Permeability by Lysophosphatidic Acid Receptor 5. Cell Mol Gastroenterol Hepatol 2021; 12:1073-1092. [PMID: 33975030 PMCID: PMC8350072 DOI: 10.1016/j.jcmgh.2021.05.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Revised: 05/03/2021] [Accepted: 05/04/2021] [Indexed: 12/10/2022]
Abstract
BACKGROUND & AIMS Epithelial cells form a monolayer at mucosal surface that functions as a highly selective barrier. Lysophosphatidic acid (LPA) is a bioactive lipid that elicits a broad range of biological effects via cognate G protein-coupled receptors. LPA receptor 5 (LPA5) is highly expressed in intestinal epithelial cells, but its role in the intestine is not well-known. Here we determined the role of LPA5 in regulation of intestinal epithelial barrier. METHODS Epithelial barrier integrity was determined in mice with intestinal epithelial cell (IEC)-specific LPA5 deletion, Lpar5ΔIEC. LPA was orally administered to mice, and intestinal permeability was measured. Dextran sulfate sodium (DSS) was used to induce colitis. Human colonic epithelial cell lines were used to determine the LPA5-mediated signaling pathways that regulate epithelial barrier. RESULTS We observed increased epithelial permeability in Lpar5ΔIEC mice with reduced claudin-4 expression. Oral administration of LPA decreased intestinal permeability in wild-type mice, but the effect was greatly mitigated in Lpar5ΔIEC mice. Serum lipopolysaccharide level and bacterial loads in the intestine and liver were elevated in Lpar5ΔIEC mice. Lpar5ΔIEC mice developed more severe colitis induced with DSS. LPA5 transcriptionally regulated claudin-4, and this regulation was dependent on transactivation of the epidermal growth factor receptor, which induced localization of Rac1 at the cell membrane. LPA induced the translocation of Stat3 to the cell membrane and promoted the interaction between Rac1 and Stat3. Inhibition of Stat3 ablated LPA-mediated regulation of claudin-4. CONCLUSIONS This study identifies LPA5 as a regulator of the intestinal barrier. LPA5 promotes claudin-4 expression in IECs through activation of Rac1 and Stat3.
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Rao MC. Physiology of Electrolyte Transport in the Gut: Implications for Disease. Compr Physiol 2019; 9:947-1023. [PMID: 31187895 DOI: 10.1002/cphy.c180011] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
We now have an increased understanding of the genetics, cell biology, and physiology of electrolyte transport processes in the mammalian intestine, due to the availability of sophisticated methodologies ranging from genome wide association studies to CRISPR-CAS technology, stem cell-derived organoids, 3D microscopy, electron cryomicroscopy, single cell RNA sequencing, transgenic methodologies, and tools to manipulate cellular processes at a molecular level. This knowledge has simultaneously underscored the complexity of biological systems and the interdependence of multiple regulatory systems. In addition to the plethora of mammalian neurohumoral factors and their cross talk, advances in pyrosequencing and metagenomic analyses have highlighted the relevance of the microbiome to intestinal regulation. This article provides an overview of our current understanding of electrolyte transport processes in the small and large intestine, their regulation in health and how dysregulation at multiple levels can result in disease. Intestinal electrolyte transport is a balance of ion secretory and ion absorptive processes, all exquisitely dependent on the basolateral Na+ /K+ ATPase; when this balance goes awry, it can result in diarrhea or in constipation. The key transporters involved in secretion are the apical membrane Cl- channels and the basolateral Na+ -K+ -2Cl- cotransporter, NKCC1 and K+ channels. Absorption chiefly involves apical membrane Na+ /H+ exchangers and Cl- /HCO3 - exchangers in the small intestine and proximal colon and Na+ channels in the distal colon. Key examples of our current understanding of infectious, inflammatory, and genetic diarrheal diseases and of constipation are provided. © 2019 American Physiological Society. Compr Physiol 9:947-1023, 2019.
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Affiliation(s)
- Mrinalini C Rao
- Department of Physiology and Biophysics, University of Illinois at Chicago, Chicago, Illinois, USA
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Jenkin KA, He P, Yun CC. Expression of lysophosphatidic acid receptor 5 is necessary for the regulation of intestinal Na +/H + exchanger 3 by lysophosphatidic acid in vivo. Am J Physiol Gastrointest Liver Physiol 2018; 315:G433-G442. [PMID: 29792531 PMCID: PMC6230692 DOI: 10.1152/ajpgi.00130.2018] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Lysophosphatidic acid (LPA) is a bioactive lipid molecule, which regulates a broad range of pathophysiological processes. Recent studies have demonstrated that LPA modulates electrolyte flux in the intestine, and its potential as an antidiarrheal agent has been suggested. Of six LPA receptors, LPA5 is highly expressed in the intestine. Recent studies by our group have demonstrated activation of Na+/H+ exchanger 3 (NHE3) by LPA5. However, much of what has been elucidated was achieved using colonic cell lines that were transfected to express LPA5. In the current study, we engineered a mouse that lacks LPA5 in intestinal epithelial cells, Lpar5ΔIEC, and investigated the role of LPA5 in NHE3 regulation and fluid absorption in vivo. The intestine of Lpar5ΔIEC mice appeared morphologically normal, and the stool frequency and fecal water content were unchanged compared with wild-type mice. Basal rates of NHE3 activity and fluid absorption and total NHE3 expression were not changed in Lpar5ΔIEC mice. However, LPA did not activate NHE3 activity or fluid absorption in Lpar5ΔIEC mice, providing direct evidence for the regulatory role of LPA5. NHE3 activation involves trafficking of NHE3 from the terminal web to microvilli, and this mobilization of NHE3 by LPA was abolished in Lpar5ΔIEC mice. Dysregulation of NHE3 was specific to LPA, and insulin and cholera toxin were able to stimulate and inhibit NHE3, respectively, in both wild-type and Lpar5ΔIEC mice. The current study for the first time demonstrates the necessity of LPA5 in LPA-mediated stimulation of NHE3 in vivo. NEW & NOTEWORTHY This study is the first to assess the role of LPA5 in NHE3 regulation and fluid absorption in vivo using a mouse that lacks LPA5 in intestinal epithelial cells, Lpar5ΔIEC. Basal rates of NHE3 activity and fluid absorption, and total NHE3 expression were not changed in Lpar5ΔIEC mice. However, LPA did not activate NHE3 activity or fluid absorption in Lpar5ΔIEC mice, providing direct evidence for the regulatory role of LPA5.
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Affiliation(s)
- Kayte A. Jenkin
- 1Division of Digestive Diseases, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia
| | - Peijian He
- 1Division of Digestive Diseases, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia
| | - C. Chris Yun
- 1Division of Digestive Diseases, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia,2Atlanta Veterans’ Affairs Medical Center, Decatur, Georgia,3Winship Cancer Institute, Emory University School of Medicine, Atlanta, Georgia
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Rieg T, Dominguez Rieg JA. Reply to “Reduced NHE3 activity results in congenital diarrhea and can predispose to inflammatory bowel disease”. Am J Physiol Regul Integr Comp Physiol 2017; 312:R312. [DOI: 10.1152/ajpregu.00550.2016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2016] [Accepted: 01/08/2017] [Indexed: 11/22/2022]
Affiliation(s)
- Timo Rieg
- Division of Nephrology-Hypertension, Department of Medicine, University of California San Diego, La Jolla, California
- Veterans Affairs San Diego Healthcare System, San Diego, California; and
| | - Jessica A. Dominguez Rieg
- Veterans Affairs San Diego Healthcare System, San Diego, California; and
- Department of Basic Sciences, Bastyr University California, San Diego, California
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