This application for continued support will focus on studying how protein-protein interactions among the cystic fibrosis transmembrane conductance regulator (CFTR), multidrug resistance protein 4 (MRP4) and inducible nitric oxide synthase (iNOS) contribute to the diarrheal symptom observed in Ulcerative Colitis (UC). Our unifying hypothesis is that CFTR, NHERF2, MRP4 and iNOS form a macromolecular complex at or near the plasma membrane in gut epithelial in UC and this macromolecular complex is required for the pathogenic process of diarrhea observed in UC. Specifically, we proposed that iNOS is overexpressed at the plasma membrane of gut epithelia in UC, resulting in the production of sustained high level of nitric oxide (NO) which triggers NO-cGMP pathway and generates compartmentalized cGMP. Since iNOS forms a macromolecular complex with CFTR, NHERF2 and MRP4 at or near the plasma membrane, this NO-dependent compartmentalized cGMP triggers the hyperactivation of CFTR chloride channels and thus causes diarrhea phenotype. Disruption of the macromolecular complex will abolish the functional coupling of iNOS-dependent cGMP generation and CFTR Cl- channel function.
The specific aims of this proposal are:
Specific Aim 1. To test the hypothesis that iNOS is overexpressed in UC-affected human gut epithelia and to test whether it is coupled to CFTR and MRP4 and upregulates CFTR Cl- channel function Specific Aim 2. To test the hypothesis that iNOS, CFTR, and MRP4 form a macromolecular complex at or near the plasma membrane of gut epithelial cells and that this macromolecular complex is required for the pathogenic process of diarrhea observed in UC. The proposed studies will not only help us better understand the mechanisms underlying the diarrhea symptom commonly observed in UC, but probably provide novel targets and methods for therapeutic interventions of the disease. Therefore, the studies proposed in this application will have clinical relevance for many individuals suffering from UC and also for those suffering from certain forms of secretory diarrheas.

Public Health Relevance

In this grant proposal, we will address a novel mechanism of how protein-protein interactions can contribute to the progression of ulcerative colitis (UC)-related diarrhea. We hypothesize that the macromolecular complex of iNOS (the inducible Nitric Oxide Synthase), CFTR (Cystic Fibrosis Transmembrane Conductance Regulator), NHERF2 (Na+/H+ exchanger regulatory Factor 2) and MRP4 (Multiple drug related protein 4) is spatially and temporally coupled to cGMP (cyclic guanosine monophosphate) generation which causes CFTR-dependent chloride secretion and thus diarrhea in UC. By targeting this macromolecular complex, we may find ways to control fluid secretion and thereby control or cure the disease.

National Institute of Health (NIH)
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Research Project (R01)
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Clinical, Integrative and Molecular Gastroenterology Study Section (CIMG)
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Grey, Michael J
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Thomas, Andrew; Ramananda, Yashaswini; Mun, KyuShik et al. (2018) AC6 is the major adenylate cyclase forming a diarrheagenic protein complex with cystic fibrosis transmembrane conductance regulator in cholera. J Biol Chem 293:12949-12959
Zhang, Weiqiang; Zhang, Zhihong; Zhang, Yanhui et al. (2017) CFTR-NHERF2-LPA? Complex in the Airway and Gut Epithelia. Int J Mol Sci 18:
Arora, Kavisha; Huang, Yunjie; Mun, Kyushik et al. (2017) Guanylate cyclase 2C agonism corrects CFTR mutants. JCI Insight 2:
Arora, Kavisha; Yarlagadda, Sunitha; Zhang, Weiqiang et al. (2016) Personalized medicine in cystic fibrosis: genistein supplementation as a treatment option for patients with a rare S1045Y-CFTR mutation. Am J Physiol Lung Cell Mol Physiol 311:L364-74
Sinha, Chandrima; Arora, Kavisha; Naren, Anjaparavanda P (2016) Methods to Study Mrp4-containing Macromolecular Complexes in the Regulation of Fibroblast Migration. J Vis Exp :53973
Zhang, W; Zhang, X; Zhang, Y H et al. (2016) Lumacaftor/ivacaftor combination for cystic fibrosis patients homozygous for Phe508del-CFTR. Drugs Today (Barc) 52:229-37
Giridhar, Premkumar Vummidi; Bell, Sheila M; Sridharan, Anusha et al. (2016) Airway Epithelial KIF3A Regulates Th2 Responses to Aeroallergens. J Immunol 197:4228-4239
Sinha, Chandrima; Zhang, Weiqiang; Moon, Chang Suk et al. (2015) Capturing the Direct Binding of CFTR Correctors to CFTR by Using Click Chemistry. Chembiochem 16:2017-22
Riazanski, Vladimir; Gabdoulkhakova, Aida G; Boynton, Lin S et al. (2015) TRPC6 channel translocation into phagosomal membrane augments phagosomal function. Proc Natl Acad Sci U S A 112:E6486-95
Moon, Changsuk; Zhang, Weiqiang; Ren, Aixia et al. (2015) Compartmentalized accumulation of cAMP near complexes of multidrug resistance protein 4 (MRP4) and cystic fibrosis transmembrane conductance regulator (CFTR) contributes to drug-induced diarrhea. J Biol Chem 290:11246-57

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