title: Function and regulation of TRPP2 ion channel revealed by a gain-of-function mutant.
abstract: Mutations in polycystin-1 and transient receptor potential polycystin 2 (TRPP2) account for almost all clinically identified cases of autosomal dominant polycystic kidney disease (ADPKD), one of the most common human genetic diseases. TRPP2 functions as a cation channel in its homomeric complex and in the TRPP2/polycystin-1 receptor/ion channel complex. The activation mechanism of TRPP2 is unknown, which significantly limits the study of its function and regulation. Here, we generated a constitutively active gain-of-function (GOF) mutant of TRPP2 by applying a mutagenesis scan on the S4-S5 linker and the S5 transmembrane domain, and studied functional properties of the GOF TRPP2 channel. We found that extracellular divalent ions, including Ca(2+), inhibit the permeation of monovalent ions by directly blocking the TRPP2 channel pore. We also found that D643, a negatively charged amino acid in the pore, is crucial for channel permeability. By introducing single-point ADPKD pathogenic mutations into the GOF TRPP2, we showed that different mutations could have completely different effects on channel activity. The in vivo function of the GOF TRPP2 was investigated in zebrafish embryos. The results indicate that, compared with wild type (WT), GOF TRPP2 more efficiently rescued morphological abnormalities, including curly tail and cyst formation in the pronephric kidney, caused by down-regulation of endogenous TRPP2 expression. Thus, we established a GOF TRPP2 channel that can serve as a powerful tool for studying the function and regulation of TRPP2. The GOF channel may also have potential application for developing new therapeutic strategies for ADPKD.
authors.affiliation: Department of Biological Sciences, St. John's University, Queens, NY 11439;
authors.forename: Mahmud
authors.initials: M
authors.lastname: Arif Pavel
authors.affiliation: Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, CT 06520;
authors.forename: Caixia
authors.initials: C
authors.lastname: Lv
authors.affiliation: Department of Biological Sciences, St. John's University, Queens, NY 11439;
authors.forename: Courtney
authors.initials: C
authors.lastname: Ng
authors.affiliation: Department of Physiology and Biophysics, Weill Cornell Medical College, New York, NY 10065;
authors.forename: Lei
authors.initials: L
authors.lastname: Yang
authors.affiliation: Department of Biological Sciences, St. John's University, Queens, NY 11439;
authors.forename: Parul
authors.initials: P
authors.lastname: Kashyap
authors.affiliation: Department of Biological Sciences, St. John's University, Queens, NY 11439;
authors.forename: Clarissa
authors.initials: C
authors.lastname: Lam
authors.affiliation: Department of Biological Sciences, St. John's University, Queens, NY 11439;
authors.forename: Victoria
authors.initials: V
authors.lastname: Valentino
authors.affiliation: Department of Biological Sciences, St. John's University, Queens, NY 11439;
authors.forename: Helen Y
authors.initials: HY
authors.lastname: Fung
authors.affiliation: Department of Biological Sciences, St. John's University, Queens, NY 11439;
authors.forename: Thomas
authors.initials: T
authors.lastname: Campbell
authors.affiliation: Department of Biological Sciences, St. John's University, Queens, NY 11439;
authors.forename: Simon Geir
authors.initials: SG
authors.lastname: Møller
authors.affiliation: Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, CT 06520;
authors.forename: David
authors.initials: D
authors.lastname: Zenisek
authors.affiliation: Department of Biology, Queens College, City University of New York, Queens, NY 11367; The Graduate Center, City University of New York, New York, NY 10016.
authors.forename: Nathalia G
authors.initials: NG
authors.lastname: Holtzman
authors.affiliation: Department of Biological Sciences, St. John's University, Queens, NY 11439; yuy2@stjohns.edu.
authors.forename: Yong
authors.initials: Y
authors.lastname: Yu
mesh_terms: D000584:Amiloride / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism; D055785:Gene Knockdown Techniques; D006801:Humans; D009154:Mutation / Q000235:genetics; D017354:Point Mutation / Q000235:genetics; D016891:Polycystic Kidney, Autosomal Dominant / Q000235:genetics; D012430:Ruthenium Red / Q000494:pharmacology; D050396:TRPP Cation Channels / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D015027:Zebrafish / Q000196:embryology
chemical_list: D000584:Amiloride; D002118:Calcium; D012430:Ruthenium Red; D050396:TRPP Cation Channels
keywords: TRP channels; TRPP2; autosomal dominant polycystic kidney disease; gain of function; polycystin