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Description
Retinal dystrophies are a heterogeneous group of inherited diseases that lead to a progressive, severe and irreversible loss of vision by altering the anatomy and/or function of the retina. There is currently no causative cure, but research is being carried out to find ways of treating it with gene and cell therapies. These diseases can cause damage to the photoreceptor cells. The most common retinal ciliopathy, Retinitis Pigmentosa is the leading cause of inherited blindness worldwide. Retinal ciliopathies are often not evident until their advanced stages, when their symptoms become apparent. The genetic information contained in the DNA of every person determines whether a retinal ciliopathy will develop, and, consequently, these hereditary conditions cannot be prevented. However, the modern science attempt to edit genetic information in our DNA to repair or erase damaged genes. In retinal ciliopathies, the symptoms of disease can be unfortunately determined by more than one gene, which makes the gene therapy approach difficult. These different genes involved into pathogenesis of retinal ciliopathies code certain proteins, which interact with each other’s. Identifying the interactions between these proteins may help to propose a novel causative treatment. The aim of the project is to experimentally simulate the retinal ciliopathy symptoms in cultured cells and in animal model by introducing mutant proteins, and to track interactions of these proteins with other protein networks. After we will recognize which interactions are altered, we hope to be able to propose targeted treatment that will repair protein network and alleviate symptoms of the disease. Although there are different genes involved in the pathogenesis of retinal ciliopathies, they may have common protein interactions, which would become one target for treatment of these diverse diseases. The project will employ the most advanced tools in proteomic and experimental ophthalmology research.
Summary of project results
The retina is the neural part of the eye responsible for detecting light and converting it into visual information, which is then transmitted to the brain. Retinal photoreceptors are the actual light-sensitive cells that respond to light. We distinguish two types of photoreceptors, rods, and cones, which are the initial part of the visual pathway. These cells have developed very complex and advanced structures, and the cilium is one of them. Since the pathogenesis of retinal dystrophies is mainly associated with photoreceptor cilia, they are often referred to as retinal ciliopathies. Gene expression is a chain of processes leading to protein synthesis. Proteins in a cell do not act independently but rather as part of a network of protein-protein interactions. Therefore, disease symptoms may result from abnormal protein-protein interaction networks at the molecular level. This is an original and proprietary theory formulated and currently being tested in the context of retinal dystrophies by members of the ProteoRetina team. Retinal dystrophies are a heterogeneous group of inherited diseases that lead to progressive, severe, and irreversible vision loss through alterations in the structure and/or function of the retina. Retinal ciliopathies encompass genetically and phenotypically diverse groups of diseases, caused by mutations in almost 200 genes. To be more specific for our project, we focused on genes that are shared by different retinal ciliopathy phenotypes and we aimed to build the protein-protein interaction landscape for these genes. The results we obtained will facilitate us to identified therapeutic targets for further treatment. To achieve this, we applied cloning and cell culture techniques followed by Mass Spectrometry analysis to generate protein interaction data. Parallelly, we conducted in vivo study using transgenic retinal ciliopathy mice to characterize retinal ciliopathy phenotypes and to assess retinal function using electroretinography.
The major goal of our project was to elucidate mechanisms of retinal ciliopathies via system and molecular biology approaches, the findings of which in turn can suggest new targets for diagnosis and treatment of these diseases. Specific goals were to construct protein-protein interaction networks of retinal ciliopathy genes to associate with the phenotype of retinal ciliopathies, and to understand disease relevant protein-protein interaction in vitro, ex vivo and in vivo.
Currently, there is no widely available causative treatment for these diseases, but research is being conducted to find new therapies using gene and cell therapies. The only therapy still undergoing evaluation, Luxturna®, may be applied to patients with one of over 300 known mutations responsible for the development of the disease, specifically mutations in the Rpe65 gene; however, its use is limited due to its high cost. During the ProteoRetina project, we have conducted complex research activities in Katowice, Poland and Helsinki, Finland that included advance in vitro and in vivo work leading to identification of target genes and creation of complex protein-protein interaction data of these genes’ products. All these allowed us to identify “hot spot” proteins that we believe could become future treatment targets. Except in vitro tests, we have conducted extensive in vivo research using GMO mice suffering from various types of retinitis pigmentosa, to characterize phenotype of these variants. Finally, we use genetic engineering methods to tests one of identified “hot spot” proteins, to verify hypothesis of its importance in retinitis pigmentosa development.
Except research activities, we have conducted and participated in various scientific and promotion events. We organized two press conferences, with participation of national press, in order to promote and disseminate project ideas and early results. We also built project website www.proteoretina.com and we actively attended in several scientific meetings, presenting ideas and results from ProteoRetina project.
The most common retinal dystrophy, retinitis pigmentosa, occurring at a frequency of 1:3500, is a leading cause of inherited blindness worldwide, affecting up to 2.5 million people, often from childhood, leading to irreversible disability. The information contained in the DNA of everyone determines whether they will develop retinal dystrophy, and thus, it is not possible to prevent the development of these inherited diseases in the presence of genetic information damage. However, modern science attempts to edit genetic information in our DNA to repair, replace, or remove damaged genes. In retinal dystrophies, disease symptoms can be caused by mutations in more than one gene, making it difficult to create effective gene therapy. These various genes involved in the pathogenesis of retinal dystrophies encode proteins that interact with each other within intracellular protein networks. Identifying interactions between these proteins can help understand the complex mechanisms associated with retinal dystrophies and propose new causative treatments. The aim of the project was to experimentally induce retinal dystrophy in cell culture and in an animal model in mice by introducing mutated proteins into cells and tracking the interactions of these proteins with other protein networks. During the conducted research, we identified which protein interactions are altered and common in over 160 analyzed known mutations. Based on advanced bioinformatic analyses, we identified 9 proteins that we hope to propose, as part of the next project, targeted treatments to alleviate disease symptoms. Our hypothesis is that although various genes are important in the pathogenesis of retinal dystrophies, they may have common interactions with proteins that would become a common target for treating these diverse diseases. Mapping the common protein interactions in retinal ciliopathies will possibly create a way to apply more profiled, targeted, and causative treatments. Successful treatment of these diseases would also decrease socio-economic burden since patients with retinal ciliopathies require extensive medical attention during the whole life. This project may indicate the direction of treatment strategy development for patients suffering from retinal dystrophies. In our opinion, due to the lack of causative treatment, any attempt to approach retinal dystrophies with novel ideas brings new hopes for researchers to find a more efficient cure and for patients to preserve their vision.