RESUMO
Retinitis pigmentosa (RP) is a degenerative retinal disease, often caused by mutations in the G-protein-coupled receptor rhodopsin. The majority of pathogenic rhodopsin mutations cause rhodopsin to misfold, including P23H, disrupting its crucial ability to respond to light. Previous screens to discover pharmacological chaperones of rhodopsin have primarily been based on rescuing rhodopsin trafficking and localization to the plasma membrane. Here, we present methods utilizing a yeast-based assay to screen for compounds that rescue the ability of rhodopsin to activate an associated downstream G-protein signaling cascade. We engineered a yeast strain in which human rhodopsin variants were genomically integrated, and were able to demonstrate functional coupling to the yeast mating pathway, leading to fluorescent protein expression. We confirmed that a known pharmacological chaperone, 9-cis retinal, could partially rescue light-dependent activation of a disease-associated rhodopsin mutation (P23H) expressed in yeast. These novel yeast strains were used to perform a phenotypic screen of 4280 compounds from the LOPAC1280 library and a peptidomimetic library, to discover novel pharmacological chaperones of rhodopsin. The fluorescence-based assay was robust in a 96-well format, with a Z' factor of 0.65 and a signal-to-background ratio of above 14. One compound was selected for additional analysis, but it did not appear to rescue rhodopsin function in yeast. The methods presented here are amenable to future screens of small-molecule libraries, as they are robust and cost-effective. We also discuss how these methods could be further modified or adapted to perform screens of more compounds in the future.
Assuntos
Descoberta de Drogas , Avaliação Pré-Clínica de Medicamentos , Bibliotecas de Moléculas Pequenas , Leveduras/efeitos dos fármacos , Descoberta de Drogas/métodos , Avaliação Pré-Clínica de Medicamentos/métodos , Expressão Gênica , Regulação da Expressão Gênica/efeitos dos fármacos , Genes Reporter , Humanos , Mutação , Receptores Acoplados a Proteínas G/genética , Retinose Pigmentar/tratamento farmacológico , Retinose Pigmentar/etiologia , Rodopsina/genética , Transdução de Sinais/efeitos dos fármacos , Leveduras/genética , Leveduras/metabolismoRESUMO
BACKGROUND: Patients who suffer from ocular genetic diseases have special needs in terms of diagnosis and management of rare entities, low-vision needs, genetic counselling, and psychosocial adjustments that are usually not addressed by an ophthalmologist alone. The Ocular Genetics Program (OGP) at the Hospital for Sick Children, Toronto, was established in 1994 to provide comprehensive, multidisciplinary care of patients with inherited eye disorders. We now assess the benefits of such a program and of integrating research into the care of patients. METHODS: We report our experience in developing a multidisciplinary ocular genetics program and the results of a pilot patient satisfaction survey that involved 61 patients. RESULTS: The OGP multidisciplinary aspects are described. Of the 61 patients surveyed, 98% stated that they were satisfied with the OGP; 93%-96% of patients were content with "one day of appointments", "understanding of eye problem", and "coordination of ancillary tests such as visual fields test, electrophysiology, and others"; and for 70%-86% of respondents "waiting time to get an appointment", "information received on current research", and "primary health care provider adequately informed" were satisfactory. INTERPRETATION: The OGP is a unique service in Canada, which strives to provide the comprehensive care needed by ocular genetic patients. High patient satisfaction is an indicator of the success of this approach. Long waiting times for appointments and application of laboratory research in clinical care remain challenging.