Best vitelliform macular dystrophy (BD), autosomal dominant vitreoretinochoroidopathy (ADVIRC), and the autosomal recessive bestrophinopathy (ARB), together known as the bestrophinopathies, are caused by mutations in the bestrophin-1 (BEST1) gene affecting anion transport through the plasma membrane of the retinal pigment epithelium (RPE). To date, while no treatment exists a better understanding of BEST1-related pathogenesis may help to define therapeutic targets. Here, we systematically characterize functional consequences of mutant BEST1 in thirteen RPE patient cell lines differentiated from human induced pluripotent stem cells (hiPSCs). Both BD and ARB hiPSC-RPEs display a strong reduction of BEST1-mediated anion transport function compared to control, while ADVIRC mutations trigger an increased anion permeability suggesting a stabilized open state condition of channel gating. Furthermore, BD and ARB hiPSC-RPEs differ by the degree of mutant protein turnover and by the site of subcellular protein quality control with adverse effects on lysosomal pH only in the BD-related cell lines. The latter finding is consistent with an altered processing of catalytic enzymes in the lysosomes. The present study provides a deeper insight into distinct molecular mechanisms of the three bestrophinopathies facilitating functional categorization of the more than 300 known BEST1 mutations that result into the distinct retinal phenotypes.

One of the fundamental principles of social organization, age polyethism, describes behavioral maturation of workers leading to switches in task preference. Here we present a system that allows for studying division of labor (DOL) by taking advantage of the relative short life of Cardiocondyla obscurior workers and thereby the pace of behavioral transitions. By challenging same-age young and older age cohorts to de novo establish DOL into nurse and foraging tasks and by forcing nurses to precociously become foragers and vice versa we studied expression patterns of one of the best known candidates for social insect worker behavior, the foraging gene. Contrary to our expectations we found that foraging gene expression correlates with age, but not with the task foraging per se. This suggests that this nutrition-related gene, and the pathways it is embedded in, correlates with physiological changes over time and potentially primes, but not determines task preference of individual workers.

ZusammenfassungDas Bestrophin-1-Gen (BEST1) codiert für ein integrales Membranprotein und findet sich im basolateralen Aspekt des retinalen Pigmentepithels. Mutationen im BEST1 sind mit einer heterogenen Gruppe von erblichen Netzhautdystrophien assoziiert, den sog. Bestrophinopathien, die schon in jüngerem Alter zu einer Beeinträchtigung des Sehvermögens führen können. Die einzelnen Krankheitsbilder sind anhand ihrer phänotypischen Merkmale und Erbgänge abgrenzbar. Während die meisten BEST1-Mutationen einem autosomal-dominanten Erbgang folgen, bei dem bereits eine defekte Genkopie zur Erkrankung führt, sind bei der autosomal-rezessiven Bestrophinopathie heterozygote Mutationsträger i. d. R. symptomfrei. In diesem Übersichtsartikel soll am Beispiel der Bestrophinopathien die Bedeutung der Kenntnis von mutationsabhängigen Mechanismen für das Verständnis der Pathogenese, aber auch für die Entwicklung von zukünftigen Therapieansätzen, hervorgehoben werden.