Neither 4PBA nor 2-NOAA had a significant effect on the Cl? conductance of wild-type bestrophin 1 (Figs
Neither 4PBA nor 2-NOAA had a significant effect on the Cl? conductance of wild-type bestrophin 1 (Figs. bestrophin 1 associated with autosomal dominant disease (Best vitelliform macular dystrophy [BVMD]) and autosome recessive bestrophinopathy (ARB), and these small molecules have different modes of action. Both 4PBA and 2-NOAA significantly increased the channel function of mutant BVMD and ARB bestrophin 1 in HEK293T and iPSC-RPE cells derived from patients with BVMD and ARB. For 4PBA, the increased mutant channel function in BVMD and ARB iPSC-RPE was equal to that of wild-type iPSC-RPE bestrophin 1. Conclusions The MHP 133 restoration of bestrophin 1 function in patient-derived RPE confirms the US Food and Drug AdministrationCapproved drug 4PBA as a promising therapeutic treatment for bestrophinopathies. result in distinct ocular phenotypes of different inheritance patterns collectively referred to as bestrophinopathies, including Best vitelliform macular dystrophy (BVMD, OMIM#153700) and autosomal recessive bestrophinopathy (ARB, OMIM#611809).4C7 More than 250 pathogenic mutations have been identified, most being missense variants associated with BVMD. Most of the mutant bestrophin 1 proteins studied are mislocalized to the cytoplasm, although around one-third correctly traffic?to the plasma membrane. All bestrophin 1 mutants studied so far have decreased or absent Cl? current. These data suggest that different?disease mechanisms impair function leading to bestrophinopathy phenotypes. The small molecule sodium phenylbutyrate (4PBA) acts as a chemical chaperone to enhance protein folding in the endoplasmic reticulum (ER), and may also be a histone deacetylase inhibitor (HDACi) that increases stress response gene transcription8.8 A number of studies have demonstrated that 4PBA can rescue the function of mutant proteins associated with diseases including 1-anti-trypsin deficiency, cystic fibrosis, glaucoma, retinitis pigmentosa, and ARB, implying a general mechanism.9C12 In this study, we show that small molecules are able to rescue the function of mutant bestrophin 1 proteins that cause autosomal dominant (p.Y85H, p.R218C, p.L234V, p.N296S, p.K30R) as well as recessive (p.M325T, p.R255Q) retinal phenotypes. Importantly, we also demonstrate, through the generation of disease-specific patient-derived RPE generated from induced pluripotent stem cells (iPSC-RPEs) (p.K30R, p.R255Q), that such small molecules can functionally rescue mutant bestrophin 1 channel conductivity in human disease-relevant tissue. Given the cost of gene-specific therapies, compounds that can target multiple dominant and recessive diseases resulting from different mechanistic pathologies are of significant interest. Methods Cell Culture MDCKII cell lines were cultured in Dulbecco’s modified Eagle’s medium (DMEM) containing 10% (v/v) heat-inactivated fetal bovine serum (FBS), 2 mM L-glutamine, and MEM nonessential amino acid. HEK293T cells were cultured in DMEM containing 10% (v/v) FBS and 2 mM L-glutamine. All cells were incubated at 37C, 5% CO2. Generation of Mouse monoclonal to CD9.TB9a reacts with CD9 ( p24), a member of the tetraspan ( TM4SF ) family with 24 kDa MW, expressed on platelets and weakly on B-cells. It also expressed on eosinophils, basophils, endothelial and epithelial cells. CD9 antigen modulates cell adhesion, migration and platelet activation. GM1CD9 triggers platelet activation resulted in platelet aggregation, but it is blocked by anti-Fc receptor CD32. This clone is cross reactive with non-human primate Stable Cell Lines The Flp-in T-Rex system (Life Technologies, Paisley, UK) was used to generate stable MDCKII cell lines expressing wild-type, BVMD (p.L234V and p.N296S), and ARB (p.M325T) bestrophin 1. A reverse transfection protocol was used to improve the transfection efficiency. Bestrophin 1 constructs in pcDNA5/FRT/TO were cotransfected with pOG44 into MDCKII Flp-in T-Rex host cells using Lipofectamine LTX and Plus reagent (Life Technologies). Cells were selected with 400 g/mL hygromycin and 4 g/mL blasticidin for 2 weeks. Generation of iPSCs iPSCs were derived from the peripheral blood of a patient with ARB who had MHP 133 the homozygous mutation p.R255Q using Sendai virusCmediated gene transfer.13 Full details are in the Supplementary Material. Differentiation of iPSCs MHP 133 Into Retinal Pigment Epithelium p.R255Q iPSCs were differentiated to RPE as previously reported14.14 Full details are in the Supplementary Material. Wild-type iPSC-RPE was purchased from LAgen Laboratories (Rochester, MN, USA). p.K30R iPSC-RPE was a gift from Prof. Marmorstein (Mayo Clinic, Rochester, MN, USA). Transient Transfection HEK293T cells were cotransfected with wild-type or mutant bestrophin 1 and green fluorescent protein (GFP) in a 4:1 ratio using Fugene HD transfection reagent (Promega, Southampton, UK). The transfection medium was replaced with culture medium, with or without treatment, after 24 hours and incubated a further 24 hours before use. Small-Molecule Treatment Compounds were purchased from Sigma-Aldrich (Gillingham, Dorset, UK). Then, 2.5 mM of each was added to cell culture media 24 hours prior to harvesting for Western blot, immunofluorescence fixation, or patch-clamp analysis. Real-Time Quantitative RT-PCR Total RNA was extracted from stably transfected MDCKII cell lines expressing bestrophin 1.