title: BESTROPHIN1 mutations cause defective chloride conductance in patient stem cell-derived RPE.
abstract: Bestrophin1 (BEST1) is expressed in human retinal pigment epithelium (RPE) and mutations in the BEST1 gene commonly cause retinal dysfunction and macular degeneration. BEST1 is presumed to assemble into a calcium-activated chloride channel and be involved in chloride transport but there is no direct evidence in live human RPE cells to support this idea. To test whether BEST1 functions as a chloride channel in living tissue, BEST1-mutant RPE (R218H, L234P, A243T) were generated from patient-derived induced pluripotent stem cells and compared with wild-type RPE in a retinal environment, using a biosensor that visualizes calcium-induced chloride ion flux in the cell. Calcium stimulation elicited chloride ion export in normal RPE but not in RPE derived from three patients with BEST1 mutations. These data, along with three-dimensional modeling, provide evidence that BEST1 assembles into a key calcium-sensing chloride channel in human RPE.
authors.affiliation: Barbara & Donald Jonas Laboratory of Regenerative Medicine, and Bernard & Shirlee Brown Glaucoma Laboratory, Department of Pathology & Cell Biology, Institute of Human Nutrition, College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA.|Edward S. Harkness Eye Institute, New York-Presbyterian Hospital, New York, NY 10032, USA.
authors.forename: Yasmin
authors.initials: Y
authors.lastname: Moshfegh
authors.affiliation: Omics Lab.|Department of Ophthalmology and Visual Sciences.|Medical Scientist Training Program.
authors.forename: Gabriel
authors.initials: G
authors.lastname: Velez
authors.affiliation: Edward S. Harkness Eye Institute, New York-Presbyterian Hospital, New York, NY 10032, USA.
authors.forename: Yao
authors.initials: Y
authors.lastname: Li
authors.affiliation: Department of Pediatrics, University of Iowa, Iowa City, IA, USA.
authors.forename: Alexander G
authors.initials: AG
authors.lastname: Bassuk
authors.affiliation: Department of Ophthalmology and Visual Sciences.|Medical Scientist Training Program.
authors.forename: Vinit B
authors.initials: VB
authors.lastname: Mahajan
authors.affiliation: Barbara & Donald Jonas Laboratory of Regenerative Medicine, and Bernard & Shirlee Brown Glaucoma Laboratory, Department of Pathology & Cell Biology, Institute of Human Nutrition, College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA sht2@columbia.edu.|Edward S. Harkness Eye Institute, New York-Presbyterian Hospital, New York, NY 10032, USA.
authors.forename: Stephen H
authors.initials: SH
authors.lastname: Tsang
mesh_terms: D000075002:Bestrophins; D020013:Calcium Signaling; D018118:Chloride Channels / Q000235:genetics* / Q000378:metabolism*; D002712:Chlorides; D005136:Eye Proteins / Q000235:genetics* / Q000378:metabolism*; D006801:Humans; D057026:Induced Pluripotent Stem Cells / Q000378:metabolism; D009154:Mutation; D055213:Retinal Pigment Epithelium / Q000378:metabolism; D057826:Vitelliform Macular Dystrophy / Q000235:genetics
chemical_list: C113133:BEST1 protein, human; D000075002:Bestrophins; D018118:Chloride Channels; D002712:Chlorides; D005136:Eye Proteins