Mechanisms of CFTR Functional Variants That Impair Regulated Bicarbonate Permeation and Increase Risk for Pancreatitis but Not for Cystic Fibrosis

• Autores: LaRusch, Jessica; Jung, Jinsei; General, Ignacio; Lewis, Michele D.; Park, Hyun Woo; Brand, Randall E.; Gelrud, Andres; Anderson, Michelle A.; Banks, Peter A.; Conwell, Darwin; Lawrence, Christopher; Romagnuolo, Joseph; Baillie, John; Alkaade, Samer; Cote, Gregory; Gardner, Timothy B.; Amann, Stephen T.; Slivka, Adam; Sandhu, Bimaljit; Aloe, Amy; Kienholz, Michelle L.; Yadav, Dhiraj; Barmada, M. Michael; Bahar, Ivet; Lee, Min Goo; Whitcomb, David C.; North American Pancreatitis Study Group
• Año de publicación: 2014
• Idioma: inglés
• Tipo de recurso: artículo
• Materia: CYSTIC FIBROSIS; PANCREATITIS; MOLECULAR MODELLING; ION CHANNEL
• Institución: Consejo Nacional de Investigaciones Científicas y Técnicas

CFTR is a dynamically regulated anion channel. Intracellular WNK1-SPAK activation causes CFTR to change permeability and conductance characteristics from a chloride-preferring to bicarbonate-preferring channel through unknown mechanisms. Two severe CFTR mutations (CFTRsev) cause complete loss of CFTR function and result in cystic fibrosis (CF), a severe genetic disorder affecting sweat glands, nasal sinuses, lungs, pancreas, liver, intestines, and male reproductive system. We hypothesize that those CFTR mutations that disrupt the WNK1-SPAK activation mechanisms cause a selective, bicarbonate defect in channel function (CFTRBD) affecting organs that utilize CFTR for bicarbonate secretion (e.g. the pancreas, nasal sinus, vas deferens) but do not cause typical CF. To understand the structural and functional requirements of the CFTR bicarbonate-preferring channel, we (a) screened 984 well-phenotyped pancreatitis cases for candidate CFTRBD mutations from among 81 previously described CFTR variants; (b) conducted electrophysiology studies on clones of variants found in pancreatitis but not CF; (c) computationally constructed a new, complete structural model of CFTR for molecular dynamics simulation of wild-type and mutant variants; and (d) tested the newly defined CFTRBD variants for disease in non-pancreas organs utilizing CFTR for bicarbonate secretion. Nine variants (CFTR R74Q, R75Q, R117H, R170H, L967S, L997F, D1152H, S1235R, and D1270N) not associated with typical CF were associated with pancreatitis (OR 1.5, p = 0.002). Clones expressed in HEK 293T cells had normal chloride but not bicarbonate permeability and conductance with WNK1-SPAK activation. Molecular dynamics simulations suggest physical restriction of the CFTR channel and altered dynamic channel regulation. Comparing pancreatitis patients and controls, CFTRBD increased risk for rhinosinusitis (OR 2.3, p<0.005) and male infertility (OR 395, p<<0.0001). WNK1-SPAK pathway-activated increases in CFTR bicarbonate permeability are altered by CFTRBD variants through multiple mechanisms. CFTRBD variants are associated with clinically significant disorders of the pancreas, sinuses, and male reproductive system.
Fil: LaRusch, Jessica. Univeristy of Pittsburgh. School of Medicine; Estados Unidos
Fil: Jung, Jinsei. Yonsei University College of Medicine; Corea del Sur
Fil: General, Ignacio. University of Pittsburgh; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina
Fil: Lewis, Michele D.. Mayo Clinic. Division of Gastroenterology and Hepatology; Estados Unidos
Fil: Park, Hyun Woo. Yonsei University College of Medicine; Corea del Sur
Fil: Brand, Randall E.. Univeristy of Pittsburgh. School of Medicine; Estados Unidos
Fil: Gelrud, Andres. Univeristy of Pittsburgh. School of Medicine; Estados Unidos
Fil: Anderson, Michelle A.. University of Michigan; Estados Unidos
Fil: Banks, Peter A.. Brigham and Women’s Hospital. Division of Gastroenterology; Estados Unidos
Fil: Conwell, Darwin. Brigham and Women’s Hospital. Division of Gastroenterology; Estados Unidos
Fil: Lawrence, Christopher. Medical University of South Carolina; Estados Unidos
Fil: Romagnuolo, Joseph. Medical University of South Carolina; Estados Unidos
Fil: Baillie, John. University of Duke; Estados Unidos
Fil: Alkaade, Samer. St. Louis University. School of Medicine; Estados Unidos
Fil: Cote, Gregory. Indiana University; Estados Unidos
Fil: Gardner, Timothy B.. Dartmouth-Hitchcock Medical Center; Estados Unidos
Fil: Amann, Stephen T.. North Mississippi Medical Center; Estados Unidos
Fil: Slivka, Adam. Univeristy of Pittsburgh. School of Medicine; Estados Unidos
Fil: Sandhu, Bimaljit. Virginia Commonwealth University Medical Center; Estados Unidos
Fil: Aloe, Amy. Univeristy of Pittsburgh. School of Medicine; Estados Unidos
Fil: Kienholz, Michelle L.. Univeristy of Pittsburgh. School of Medicine; Estados Unidos
Fil: Yadav, Dhiraj. Univeristy of Pittsburgh. School of Medicine; Estados Unidos
Fil: Barmada, M. Michael. Univeristy of Pittsburgh. School of Medicine; Estados Unidos
Fil: Bahar, Ivet. Univeristy of Pittsburgh. School of Medicine; Estados Unidos
Fil: Lee, Min Goo. Yonsei University College of Medicine; Corea del Sur
Fil: Whitcomb, David C.. Univeristy of Pittsburgh. School of Medicine; Estados Unidos
Fil: North American Pancreatitis Study Group. No especifica;