Retinal Proteomics of a Mouse Model of Dystroglycanopathies Reveals Molecular Alterations in Photoreceptors.
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ABSTRACT:
SUBMITTER: Uribe ML
PROVIDER: S-EPMC8280732 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Mutations in the POMT1 gene, encoding a protein O-mannosyltransferase essential for alpha-dystroglycan (α-DG) glycosylation, are frequently observed in a group of rare congenital muscular dystrophies, collectively known as dystroglycanopathies. However, it is hitherto unclear whether the effects seen in affected patients can be fully ascribed to α-DG hypoglycosylation. To study this, we here used comparative mass spectrometry-based proteomics and immunofluorescence microscopy, in order to investigate the changes in retina of mice in which Pomt1 is specifically knocked out in photoreceptor cells. Our results demonstrate significant proteomic changes and associated structural alteration in photoreceptor cells of Pomt1 cKO mice. In addition to effects related to impaired α-DG O-mannosylation, we observed morphological impairments in the outer segment that are associated with dysregulation of a relatively understudied POMT1 substrate (KIAA1549), BBSome proteins and retinal stress markers. In conclusion, our study provides new hypotheses to explain the phenotypic changes that are observed in the retina of patients with dystroglycanopathies.
2021-09-10 | PXD023704 | Pride
Project description:Aims/hypothesisDiabetic retinopathy is a major complication of type 2 diabetes and the leading cause of blindness in adults of working age. Neuronal defects are known to occur early in disease, but the source of this dysfunction is unknown. The aim of this study was to examine differences in the retinal membrane proteome among non-diabetic mice and mouse models of diabetes either with or without metformin treatment.MethodsAlterations in the retinal membrane proteome of 10-week-old diabetic db/db mice, diabetic db/db mice orally treated with the anti-hyperglycaemic metformin, and congenic wild-type littermates were examined using label-free mass spectrometry. Pathway enrichment analysis was completed with Genomatix and Ingenuity. Alterations in Slc17a7 mRNA and vesicular glutamate transporter 1 (VGLUT1) protein expression were evaluated using real-time quantitative PCR and IMMUNOFLUORESCENCE.ResultsA total of 98 proteins were significantly differentially abundant between db/db and wild-type animals. Pathway enrichment analysis indicated decreases in levels of proteins related to synaptic transmission and cell signalling. Metformin treatment produced 63 differentially abundant proteins compared with untreated db/db mice, of which only 43 proteins were found to occur in both datasets, suggesting that treatment only partially normalises the alterations induced by diabetes. VGLUT1, which is responsible for loading glutamate into synaptic vesicles, was found to be differentially abundant in db/db mice and was not normalised by metformin. The decrease in Slc17a7/VGLUT1 was confirmed by transcriptomic and immunocytochemical analysis.Conclusions/interpretationThese findings expand the knowledge of the protein changes in diabetic retinopathy and suggest that membrane-associated signalling proteins are susceptible to changes that are partially ameliorated by treatment
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Project description:The defective glycosylation of α-dystroglycan is associated with a group of muscular dystrophies that are collectively referred to as the secondary dystroglycanopathies. Mutations in the gene encoding fukutin-related protein (FKRP) are one of the most common causes of secondary dystroglycanopathy in the UK and are associated with a wide spectrum of disease. Whilst central nervous system involvement has a prenatal onset, no studies have addressed prenatal muscle development in any of the mouse models for this group of diseases. In view of the pivotal role of α-dystroglycan in early basement membrane formation, we sought to determine if the muscle formation was altered in a mouse model of FKRP-related dystrophy.Mice with a knock-down in FKRP (FKRP(KD)) showed a marked reduction in α-dystroglycan glycosylation and reduction in laminin binding by embryonic day 15.5 (E15.5), relative to wild type controls. In addition, the total number of Pax7(+) progenitor cells in the FKRP(KD) tibialis anterior at E15.5 was significantly reduced, and myotube cluster/myofibre size showed a significant reduction in size. Moreover, myoblasts isolated from the limb muscle of these mice at E15.5 showed a marked reduction in their ability to form myotubes in vitro.These data identify an early reduction of laminin α2, reduction of myogenicity and depletion of Pax7(+) progenitor cells which would be expected to compromise subsequent postnatal muscle growth and its ability to regenerate postnatally. These findings are of significance to the development of future therapies in this group of devastating conditions.
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Project description:BackgroundRetinitis pigmentosa (RP) is an inherited retinal disease that results in photoreceptor degeneration, leading to severe vision loss or blindness. Due to its genetic heterogeneity, developing a new gene therapy to correct every genetic mutation contributing to its progression is infeasible. Photoreceptor transplantation can be harnessed to restore vision; however, this approach is limited by poor cell survival and synaptic integration into the neural retina. Thus, we developed a combined cell and gene therapy that is expected to protect photoreceptors in most, if not all, cases of RP.MethodsHuman embryonic stem cells (hESCs) modified with our FailSafe™ system were genetically engineered to overexpress sCX3CL1, an inhibitor of microglia activation that has been shown to preserve photoreceptor survival and function in mouse models of RP, independent of the genetic cause. These cells were differentiated into human retinal pigment epithelium (hRPE) cells and used as therapeutic cells due to their longevity and safety, both of which have been demonstrated in preclinical and clinical studies. Transgenic hRPE were delivered into the subretinal space of immunodeficient mice and the rd10 mouse model of RP to evaluate donor cell survival and retention of transgene expression. The outer nuclear layer was quantified to assess photoreceptor protection.ResultsTransgenic FailSafe™ hRPE (FS-hRPE) cells can survive for at least four months in the retina of immunodeficient mice and retain transgene expression. However, these cells do not persist beyond two weeks post-injection in the retina of immunocompetent rd10 recipients, despite Cyclosporine A treatment. Nevertheless, sCX3CL1-expressing FailSafe™ hRPE cells prevented photoreceptor degeneration in a local acting manner during the duration of their presence in the subretinal space.ConclusionsTransgenic hESCs differentiate into hRPE cells and retain sCX3CL1 transgene expression both in vitro and in vivo. Moreover, hRPE cells delivered to the subretinal space of rd10 mice prevented photoreceptor degeneration in a local-acting manner, suggesting that this approach could have applications for preserving photoreceptors in specific subregions of the retina, such as the macula. Overall, our study not only reveals the potential of a combined cell and gene therapy for the treatment of RP, but also the possibility of using hRPE cells to deliver therapeutic biologics in situ to treat diseases over long-term.
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Project description:Titanium dioxide as a food additive (E171) has been demonstrated to facilitate growth of chemically induced colorectal tumours in vivo and induce transcriptomic changes suggestive of an immune system impairment and cancer development. The present study aimed to investigate the molecular mechanisms behind the tumour stimulatory effects of E171 in combination with azoxymethane (AOM)/dextran sodium sulphate (DSS) and compare these results to a recent study performed under the same conditions with E171 only. BALB/c mice underwent exposure to 5?mg/kgbw/day of E171 by gavage for 2, 7, 14, and 21 days. Whole genome mRNA microarray analyses on the distal colon were performed. The results show that E171 induced a downregulation of genes involved in the innate and adaptive immune system, suggesting impairment of this system. In addition, over time, signalling genes involved in colorectal cancer and other types of cancers were modulated. In relation to cancer development, effects potentially associated with oxidative stress were observed through modulation of genes related to antioxidant production. E171 affected genes involved in biotransformation of xenobiotics which can form reactive intermediates resulting in toxicological effects. These transcriptomics data reflect the early biological responses induced by E171 which precede tumour formation in an AOM/DSS mouse model.
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Project description:Benign prostatic hyperplasia and related lower urinary tract symptoms remain common, costly, and impactful issues for aging males. The etiology and pathogenesis are multifactorial and include steroid hormone changes and inflammation. Noninvasive markers could one day inform personalized medicine, but interindividual variation and lack of healthy age-matched controls hamper research. Experimental models are appealing for insight into disease mechanisms. Here, we present a spatiotemporal proteomics study in a mouse model of hormone-induced urinary dysfunction. Urine samples were collected noninvasively across time: before, during, and after disease onset. A microcomputed tomography analysis implicated the prostate as a spatially relevant contributor to bladder outlet obstruction. Prostates were collected after disease onset and compared with control mice. Notable changes in urine include proteins representing oxidative stress defense and acute phase inflammatory response processes. In the prostate, hormone treatment led to perturbations related to an oxidative stress response and H2O2 metabolism. Several protein changes coincided in both urine and the prostate tissue, including glutathione peroxidase 3, glutathione hydrolase 1 proenzyme, and vitamin D-binding protein. This study supports the concept of noninvasive urinary biomarkers for prostate disease diagnostics. Oxidative stress and acute phase inflammatory processes were identified as key consequences of hormone-induced bladder outlet obstruction. Future research into antioxidants and anti-inflammatories in prostate diseases appears promising.
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