The role of small molecules and their effect on the molecular mechanisms of early retinal organoid development

Early in vivo embryonic retinal development is a well-documented and evolutionary conserved process. The specification towards eye development is temporally controlled by consecutive activation or inhibition of multiple key signaling pathways, such as the Wnt and hedgehog signaling pathways. Recently, with the use of retinal organoids, researchers aim to manipulate these pathways to achieve better human representative models for retinal development and disease. To achieve this, a plethora of different small molecules and signaling factors have been used at various time points and concentrations in retinal organoid differentiations, with varying success. Additions differ from protocol to protocol, but their usefulness or efficiency has not yet been systematically reviewed. Interestingly, many of these small molecules affect the same and/or multiple pathways, leading to reduced reproducibility and high variability between studies. In this review, we make an inventory of the key signaling pathways involved in early retinogenesis and their effect on the development of the early retina in vitro. Further, we provide a comprehensive overview of the small molecules and signaling factors that are added to retinal organoid differentiation protocols, documenting the molecular and functional effects of these additions. Lastly, we comparatively evaluate several of these factors using our established retinal organoid methodology.Ophthalmic researc

A review of treatment modalities in gyrate atrophy of the choroid and retina (GACR)

Gyrate atrophy of the choroid and retina (GACR) is a rare inborn error of amino acid metabolism caused by bi-allelic variations in OAT. GACR is characterised by vision decline in early life eventually leading to complete blindness, and high plasma ornithine levels. There is no curative treatment for GACR, although several therapeutic modalities aim to slow progression of the disease by targeting different steps within the ornithine pathway. No international treatment protocol is available. We systematically collected all international literature on therapeutic interventions in GACR to provide an overview of published treatment effects. Methods: Following the PRISMA guidelines, we conducted a systematic review of the English literature until December 22nd 2020. PubMed and Embase databases were searched for studies related to therapeutic interventions in patients with GACR. Results: A total of 33 studies (n = 107 patients) met the inclusion criteria. Most studies were designed as case reports (n = 27) or case series (n = 4). No randomised controlled trials or large cohort studies were found. Treatments applied were protein-restricted diets, pyridoxine supplementation, creatine or creatine precursor supplementation, L-lysine supplementation, and proline supplementation. Protein-restricted diets lowered ornithine levels ranging from 16.0-91.2%. Pyridoxine responsiveness was reported in 30% of included mutations. Lysine supplementation decreased ornithine levels with 21-34%. Quality assessment showed low to moderate quality of the articles. Conclusions: Based primarily on case reports ornithine levels can be reduced by using a protein restricted diet, pyridoxine supplementation (variation-dependent) and/or lysine supplementation. The lack of pre-defined clinical outcome measures and structural follow-up in all included studies impeded conclusions on clinical effectiveness. Future research should be aimed at 1) Unravelling the OAT biochemical pathway to identify other possible pathologic metabolites besides ornithine, 2) Pre-defining GACR specific clinical outcome measures, and 3) Establishing an international historical cohort. (c) 2021 The Authors. Published by Elsevier Inc. This is an open access article under the CC BY license (http:// creativecommons.org/licenses/by/4.0/).Ophthalmic researc

Supplementary Material for: Oncogenic Properties of Candidate Oncogenes in Chromosome Region 17p11.2p12 in Human Osteosarcoma

<p>Osteosarcomas are primary tumors of bone that most often develop in adolescents. They are characterized by complex genomic changes including amplifications, deletions, and translocations. The chromosome region 17p11.2p12 is frequently amplified in human high grade osteosarcomas (25% of cases), suggesting the presence of one or more oncogenes. In previous studies, we identified 9 candidate oncogenes in this region <i>(GID4</i>,<i> ARGHAP44</i>,<i> LRRC75A-AS1</i>, <i>TOP3A</i>,<i> COPS3</i>,<i> SHMT1</i>,<i> PRPSAP2</i>,<i> PMP22</i>, and<i> RASD1)</i>. The aim of the present study was to determine their oncogenic properties. Therefore, we generated osteosarcoma cell lines overexpressing these genes, except for <i>LRRC75A-AS1</i> and <i>PRPSAP2</i>, and subjected these to functional oncogenic assays. We found that <i>TOP3A</i>, <i>SHMT1</i>, and <i>RASD1</i> overexpression provided increased proliferation and that <i>ARGHAP44</i>, <i>COPS3</i>, and <i>PMP22</i> overexpression had a stimulatory effect on migration and invasion of the cells. <i>COPS3</i> and <i>PMP22</i> overexpression additionally improved the ability of the cells to form new colonies. No oncogenic effect could be demonstrated for <i>GID4</i> overexpression. We conclude that the concerted amplification-mediated overexpression of these genes in 17p11.2p12 may contribute to the oncogenic process in malignant osteosarcoma.</p