Browsing by Subject "Retinal degeneration"
Now showing 1 - 8 of 8
Results Per Page
Sort Options
Item Differentiation and characterization of cell types associated with retinal degenerative diseases using human induced pluripotent stem cells(2014-07-31) Gupta, Manav; Meyer, Jason S.; Belecky-Adams, Teri; Randall, Stephen Karl, 1953-Human induced pluripotent stem (iPS) cells have the unique ability to differentiate into 200 or so somatic cell types that make up the adult human being. The use of human iPS cells to study development and disease is a highly exciting and interdependent field that holds great promise in understanding and elucidating mechanisms behind cellular differentiation with future applications in drug screening and cell replacement studies for complex and currently incurable cellular degenerative disorders. The recent advent of iPS cell technology allows for the generation of patient-specific cell lines that enable us to model the progression of a disease phenotype in a human in vitro model. Differentiation of iPS cells toward the affected cell type provides an unlimited source of diseased cells for examination, and to further study the developmental progression of the disease in vitro, also called the “disease-in-a-dish” model. In this study, efforts were undertaken to recapitulate the differentiation of distinct retinal cell affected in two highly prevalent retinal diseases, Usher syndrome and glaucoma. Using a line of Type III Usher Syndrome patient derived iPS cells efforts were undertaken to develop such an approach as an effective in vitro model for studies of Usher Syndrome, the most commonly inherited disorder affecting both vision and hearing. Using existing lines of iPS cells, studies were also aimed at differentiation and characterization of the more complex retinal cell types, retinal ganglion cells (RGCs) and astrocytes, the cell types affected in glaucoma, a severe neurodegenerative disease of the retina leading to eventual irreversible blindness. Using a previously described protocol, the iPS cells were directed to differentiate toward a retinal fate through a step-wise process that proceeds through all of the major stages of neuroretinal development. The differentiation process was monitored for a period of 70 days for the differentiation of retinal cell types and 150 days for astrocyte development. The different stages of differentiation and the individually derived somatic cell types were characterized by the expression of developmentally associated transcription factors specific to each cell type. Further approaches were undertaken to characterize the morphological differences between RGCs and other neuroretinal cell types derived in the process. The results of this study successfully demonstrated that Usher syndrome patient derived iPS cells differentiated to the affected photoreceptors of Usher syndrome along with other mature retinal cell types, chronologically analogous to the development of the cell types in a mature human retina. This study also established a robust method for the in vitro derivation of RGCs and astrocytes from human iPS cells and provided novel methodologies and evidence to characterize these individual somatic cell types. Overall, this study provides a unique insight into the application of human pluripotent stem cell biology by establishing a novel platform for future studies of in vitro disease modeling of the retinal degenerative diseases: Usher syndrome and glaucoma. In downstream applications of this study, the disease relevant cell types derived from human iPS cells can be used as tools to further study disease progression, drug screening and cell replacement strategies.Item In Vivo Identification and Manipulation of the Ca2+ Selectivity Filter in the Drosophila Transient Receptor Potential Channel(Society for Neuroscience, 2007-01-17) Liu, Che H.; Wang, Tao; Postma, Marten; Obukhov, Alexander G.; Montell, Craig; Hardie, Roger C.; Cellular and Integrative Physiology, School of MedicineNull mutations in the transient receptor potential (trp) gene eliminate the major, Ca2+-selective component of the light-sensitive conductance in Drosophila photoreceptors. Although it is the prototypical member of the TRP ion channel superfamily, conclusive evidence that TRP is a pore-forming channel subunit in vivo is lacking. We show here that mutating a specific acidic residue (Asp621) in the putative pore virtually eliminated Ca2+ permeation in vivo and altered other biophysical properties of the native TRP conductance. The results identify Asp621 as a critical residue of the TRP Ca2+ selectivity filter, provide the first rigorous demonstration that a TRP protein is a pore-forming subunit in any native system, and point to the likely location of the pore in mammalian canonical TRP channels. The specific elimination of Ca2+ permeation in TRP also provided a unique opportunity to address the roles of Ca2+ influx in vivo. We found that Asp621 mutations profoundly affected several key aspects of the light response and caused light-dependent retinal degeneration.Item Mks6 mutations reveal tissue- and cell type-specific roles for the cilia transition zone(Federation of American Society of Experimental Biology (FASEB), 2019-01) Lewis, Wesley R.; Bales, Katie L.; Revell, Dustin Z.; Croyle, Mandy J.; Engle, Staci E.; Song, Cheng Jack; Malarkey, Erik B.; Uytingco, Cedric R.; Shan, Dan; Antonellis, Patrick J.; Nagy, Tim R.; Kesterson, Robert A.; Mrug, Michal M.; Martens, Jeffrey R.; Berbari, Nicolas F.; Gross, Alecia K.; Yoder, Bradley K.; Biology, School of ScienceThe transition zone (TZ) is a domain at the base of the cilium that is involved in maintaining ciliary compartment-specific sensory and signaling activity by regulating cilia protein composition. Mutations in TZ proteins result in cilia dysfunction, often causing pleiotropic effects observed in a group of human diseases classified as ciliopathies. The purpose of this study is to describe the importance of the TZ component Meckel-Grüber syndrome 6 (Mks6) in several organ systems and tissues regarding ciliogenesis and cilia maintenance using congenital and conditional mutant mouse models. Similar to MKS, congenital loss of Mks6 is embryonic lethal, displaying cilia loss and altered cytoskeletal microtubule modifications but only in specific cell types. Conditional Mks6 mutants have a variable cystic kidney phenotype along with severe retinal degeneration with mislocalization of phototransduction cascade proteins. However, other phenotypes, such as anosmia and obesity, which are typically associated with cilia and TZ dysfunction, were not evident. These data indicate that despite Mks6 being a core TZ component, it has tissue- or cell type-specific functions important for cilia formation and cilia sensory and signaling activities.Item Morphological and Molecular Defects in Human Three-Dimensional Retinal Organoid Model of X-Linked Juvenile Retinoschisis(Elsevier, 2019-11-12) Huang, Kang-Chieh; Wang, Mong-Lien; Chen, Shih-Jen; Kuo, Jean-Cheng; Wang, Won-Jing; Nguyen, Phan Nguyen Nhi; Wahlin, Karl J.; Lu, Jyh-Feng; Tran, Audrey A.; Shi, Michael; Chien, Yueh; Yarmishyn, Aliaksandr A.; Tsai, Ping-Hsing; Yang, Tien-Chun; Jane, Wann-Neng; Chang, Chia-Ching; Peng, Chi-Hsien; Schlaeger, Thorsten M.; Chiou, Shih-Hwa; Biology, School of ScienceX-linked juvenile retinoschisis (XLRS), linked to mutations in the RS1 gene, is a degenerative retinopathy with a retinal splitting phenotype. We generated human induced pluripotent stem cells (hiPSCs) from patients to study XLRS in a 3D retinal organoid in vitro differentiation system. This model recapitulates key features of XLRS including retinal splitting, defective retinoschisin production, outer-segment defects, abnormal paxillin turnover, and impaired ER-Golgi transportation. RS1 mutation also affects the development of photoreceptor sensory cilia and results in altered expression of other retinopathy-associated genes. CRISPR/Cas9 correction of the disease-associated C625T mutation normalizes the splitting phenotype, outer-segment defects, paxillin dynamics, ciliary marker expression, and transcriptome profiles. Likewise, mutating RS1 in control hiPSCs produces the disease-associated phenotypes. Finally, we show that the C625T mutation can be repaired precisely and efficiently using a base-editing approach. Taken together, our data establish 3D organoids as a valid disease model.Item Restoring retinal polyunsaturated fatty acid balance and retina function by targeting ceramide in AdipoR1-deficient mice(Elsevier, 2024) Lewandowski, Dominik; Gao, Fangyuan; Imanishi, Sanae; Tworak, Aleksander; Bassetto, Marco; Dong, Zhiqian; Pinto, Antonio F. M.; Tabaka, Marcin; Kiser, Philip D.; Imanishi, Yoshikazu; Skowronska-Krawczyk, Dorota; Palczewski, Krzysztof; Ophthalmology, School of MedicineMutations in the adiponectin receptor 1 gene (AdipoR1) lead to retinitis pigmentosa and are associated with age-related macular degeneration. This study explores the effects of AdipoR1 gene deficiency in mice, revealing a striking decline in ω3 polyunsaturated fatty acids (PUFA), an increase in ω6 fatty acids, and elevated ceramides in the retina. The AdipoR1 deficiency impairs peroxisome proliferator-activated receptor α signaling, which is crucial for FA metabolism, particularly affecting proteins associated with FA transport and oxidation in the retina and retinal pigmented epithelium. Our lipidomic and proteomic analyses indicate changes that could affect membrane composition and viscosity through altered ω3 PUFA transport and synthesis, suggesting a potential influence of AdipoR1 on these properties. Furthermore, we noted a reduction in the Bardet-Biedl syndrome proteins, which are crucial for forming and maintaining photoreceptor outer segments that are PUFA-enriched ciliary structures. Diminution in Bardet-Biedl syndrome-proteins content combined with our electron microscopic observations raises the possibility that AdipoR1 deficiency might impair ciliary function. Treatment with inhibitors of ceramide synthesis led to substantial elevation of ω3 LC-PUFAs, alleviating photoreceptor degeneration and improving retinal function. These results serve as the proof of concept for a ceramide-targeted strategy to treat retinopathies linked to PUFA deficiency, including age-related macular degeneration.Item Systemic Injection of RPE65-Programmed Bone Marrow-Derived Cells Prevents Progression of Chronic Retinal Degeneration(Elsevier, 2017-04-05) Qi, Xiaoping; Pay, S. Louise; Yan, Yuanqing; Thomas, James, Jr.; Lewin, Alfred S.; Chang, Lung-Ji; Grant, Maria B.; Boulton, Michael E.; Ophthalmology, School of MedicineBone marrow stem and progenitor cells can differentiate into a range of non-hematopoietic cell types, including retinal pigment epithelium (RPE)-like cells. In this study, we programmed bone marrow-derived cells (BMDCs) ex vivo by inserting a stable RPE65 transgene using a lentiviral vector. We tested the efficacy of systemically administered RPE65-programmed BMDCs to prevent visual loss in the superoxide dismutase 2 knockdown (Sod2 KD) mouse model of age-related macular degeneration. Here, we present evidence that these RPE65-programmed BMDCs are recruited to the subretinal space, where they repopulate the RPE layer, preserve the photoreceptor layer, retain the thickness of the neural retina, reduce lipofuscin granule formation, and suppress microgliosis. Importantly, electroretinography and optokinetic response tests confirmed that visual function was significantly improved. Mice treated with non-modified BMDCs or BMDCs pre-programmed with LacZ did not exhibit significant improvement in visual deficit. RPE65-BMDC administration was most effective in early disease, when visual function and retinal morphology returned to near normal, and less effective in late-stage disease. This experimental paradigm offers a minimally invasive cellular therapy that can be given systemically overcoming the need for invasive ocular surgery and offering the potential to arrest progression in early AMD and other RPE-based diseases.Item Utilizing Zebrafish Visual Behaviors in Drug Screening for Retinal Degeneration(MDPI, 2017-06-02) Ganzen, Logan; Venkatraman, Prahatha; Pang, Chi Pui; Leung, Yuk Fai; Zhang, Mingzhi; Biochemistry and Molecular Biology, School of MedicineZebrafish are a popular vertebrate model in drug discovery. They produce a large number of small and rapidly-developing embryos. These embryos display rich visual-behaviors that can be used to screen drugs for treating retinal degeneration (RD). RD comprises blinding diseases such as Retinitis Pigmentosa, which affects 1 in 4000 people. This disease has no definitive cure, emphasizing an urgency to identify new drugs. In this review, we will discuss advantages, challenges, and research developments in using zebrafish behaviors to screen drugs in vivo. We will specifically discuss a visual-motor response that can potentially expedite discovery of new RD drugs.Item β-secretase 1 overexpression by AAV-mediated gene delivery prevents retina degeneration in a mouse model of age-related macular degeneration(Elsevier, 2023) Qi, Xiaoping; Francelin, Carolina; Mitter, Sayak; Boye, Sanford L.; Gu, Hongmei; Quigley, Judith; Grant, Maria B.; Boulton, Michael E.; Ophthalmology, School of MedicineWe reported previously that β-site amyloid precursor protein cleaving enzyme (BACE1) is strongly expressed in the normal retina and that BACE1−/− mice develop pathological phenotypes associated with age-related macular degeneration (AMD). BACE1 expression is increased within the neural retina and retinal pigment epithelium (RPE) in AMD donor eyes suggesting that increased BACE1 is compensatory. We observed that AAV-mediated BACE1 overexpression in the RPE was maintained up to 6 months after AAV1-BACE1 administration. No significant changes in normal mouse visual function or retinal morphology were observed with low-dose vector while the high-dose vector demonstrated some early pathology which regressed with time. No increase in β-amyloid was observed. BACE1 overexpression in the RPE of the superoxide dismutase 2 knockdown (SOD2 KD) mouse, which exhibits an AMD-like phenotype, prevented loss of retinal function and retinal pathology, and this was sustained out to 6 months. Furthermore, BACE1 overexpression was able to inhibit oxidative stress, microglial changes, and loss of RPE tight junction integrity (all features of AMD) in SOD2 KD mice. In conclusion, BACE1 plays a key role in retina/RPE homeostasis, and BACE1 overexpression offers a novel therapeutic target in the treatment of AMD.