Bestrophin 1 is indispensable for volume regulation in human retinal pigment epithelium cells.
In response to cell swelling, volume-regulated anion channels (VRACs) participate in a process known as regulatory volume decrease (RVD). Only recently, first insight into the molecular identity of mammalian VRACs was obtained by the discovery of the leucine-rich repeats containing 8A (LRRC8A) gene. Here, we show that bestrophin 1 (BEST1) but not LRRC8A is crucial for volume regulation in human retinal pigment epithelium (RPE) cells. Whole-cell patch-clamp recordings in RPE derived from human-induced pluripotent stem cells (hiPSC) exhibit an outwardly rectifying chloride current with characteristic functional properties of VRACs. This current is severely reduced in hiPSC-RPE cells derived from macular dystrophy patients with pathologic BEST1 mutations. Disruption of the orthologous mouse gene (Best1(-/-)) does not result in obvious retinal pathology but leads to a severe subfertility phenotype in agreement with minor endogenous expression of Best1 in murine RPE but highly abundant expression in mouse testis. Sperm from Best1(-/-) mice showed reduced motility and abnormal sperm morphology, indicating an inability in RVD. Together, our data suggest that the molecular identity of VRACs is more complex--that is, instead of a single ubiquitous channel, VRACs could be formed by cell type- or tissue-specific subunit composition. Our findings provide the basis to further examine VRAC diversity in normal and diseased cell physiology, which is key to exploring novel therapeutic approaches in VRAC-associated pathologies.
Institute of Human Genetics.
Andrea
A
Milenkovic
Institute of Human Genetics, University Eye Clinic, 93053 Regensburg, Germany;
Caroline
C
Brandl
Department of Psychiatry and Psychotherapy, Molecular Neurosciences, and.
Vladimir M
VM
Milenkovic
Department of Psychiatry and Psychotherapy, Molecular Neurosciences, and.
Thomas
T
Jendryke
Department of Physiology, University of Regensburg, 93053 Regensburg, Germany;
Lalida
L
Sirianant
Department of Physiology, University of Regensburg, 93053 Regensburg, Germany;
Potchanart
P
Wanitchakool
Institute of Human Genetics.
Stephanie
S
Zimmermann
Eye Center, Albert-Ludwigs-University of Freiburg, 79106 Freiburg, Germany; and.
Charlotte M
CM
Reiff
Institute of Human Genetics.
Franziska
F
Horling
Department of Developmental Genetics, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany.
Heinrich
H
Schrewe
Department of Physiology, University of Regensburg, 93053 Regensburg, Germany;
Rainer
R
Schreiber
Department of Physiology, University of Regensburg, 93053 Regensburg, Germany;
Karl
K
Kunzelmann
Department of Psychiatry and Psychotherapy, Molecular Neurosciences, and.
Christian H
CH
Wetzel
Institute of Human Genetics, bweb@klinik.uni-regensburg.de.
Bernhard H F
BH
Weber
D000595:Amino Acid Sequence; D000818:Animals; D000075002:Bestrophins; D048429:Cell Size; D018118:Chloride Channels / Q000378:metabolism*; D005136:Eye Proteins / Q000235:genetics / Q000378:metabolism*; D005260:Female; D005455:Fluorescent Antibody Technique; D055785:Gene Knockdown Techniques; D006801:Humans; D007473:Ion Channels / Q000172:deficiency / Q000235:genetics; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D008954:Models, Biological; D008969:Molecular Sequence Data; D009865:Oocytes / Q000378:metabolism; D018408:Patch-Clamp Techniques; D055213:Retinal Pigment Epithelium / Q000166:cytology*; D013094:Spermatozoa / Q000166:cytology; D018709:Statistics, Nonparametric; D014982:Xenopus laevis
C113133:BEST1 protein, human; C491856:Best1 protein, mouse; D000075002:Bestrophins; D018118:Chloride Channels; D005136:Eye Proteins; D007473:Ion Channels; C000589080:LRRC8A protein, mouse; D008565:Membrane Proteins
bestrophin 1; induced pluripotent stem cell; mouse sperm; retinal pigment epithelium; volume-regulated anion channel