Project description:Contribution of Nrf2 overexpression to the rescue of the RPE and/or photoreceptors in the PDEb (rd1 and rd10) model of retinal degeneration
Project description:The rd1 mouse retina is a well-studied model of retinal degeneration where rod photoreceptors undergo cell death beginning at postnatal day P10 until P21. This period coincides with photoreceptor terminal differentiation in a normal retina. We have used the rd1 retina as a model to investigate early molecular defects in developing rod photoreceptors prior to the onset of degeneration. Using a microarray approach, we performed gene profiling comparing rd1 and wild type retinas at four time points starting at P2, prior to any obvious biochemical or morphological differences, and concluding at P8, prior to the initiation of cell death. We have identified genes that are differentially regulated in the rd1 retina at early time points, which may give insights into developmental defects that precede photoreceptor cell death. This is the first report of PRA1 expression in the retina. Our data support the hypothesis that PRA1 plays an important role in vesicular trafficking between the Golgi and cilia in differentiating and mature rod photoreceptors. Retinal samples were harvested from both rd1/le and wt animals at postnatal days 2, 4, 6, and 8 for microarray. Each sample included 8-14 retinas and experiments were performed in quadruplicate. Ten micrograms of total RNA was used for cDNA systhesis in target molecule production.
Project description:The rd10 mouse is a model of retinitis pigmentosa characterized by the dysfunction of a rod-photoreceptor-specific phosphodiesterase. Compared to the rd1 mouse, retinal degeneration in the rd10 mouse begins later in age with a milder phenotype, making it ideal for investigating cell death and neuroprotective mechanisms. Alterations in the rd10 retina proteome at pre-, peak-, and post-degenerative time points were examined using a modified high-recovery filter-aided sample preparation (FASP) method and label-free mass spectrometry, generating a unique proteomic dataset on almost 3000 proteins. Our data confirmed a period of protein expression similar to age-matched wild-type mice pre-degeneration, with decreases in proteins associated with phototransduction and increases in signaling proteins at peak- and post-degenerative stages. 123 proteins were differentially expressed the rd10 retinae during peak-degeneration compared to wild-type mice. Network analysis separated these proteins into a cluster of downregulated photoreceptor proteins, and one of upregulated signaling proteins centered around GFAP, STAT3, and STAT1. This is the first study to identify alterations in STAT1 in the rd10 mouse, which were confirmed with gene expression and immunoblotting experiments. This finding proves the efficacy of our approach, and that this dataset could serve as an information source for protein alterations in retinal degeneration.
Project description:Retinal diseases exhibit extensive genetic heterogeneity and complex etiology with varying onset and severity. Mutations in over 200 genes can lead to photoreceptor dysfunction and/or cell death in retinal neurodegeneration. To deduce molecular pathways that initiate and/or drive cell death, we adopted a temporal multi-omics approach and examined molecular and cellular events in newborn and developing photoreceptors before the onset of degeneration in a widely-used Pde6brd1/rd1 (rd1) mouse, a model of autosomal recessive retinitis pigmentosa caused by PDE6B mutations. Transcriptome profiling of neonatal and developing rods from the rd1 retina revealed early downregulation of genes associated with anabolic pathways and energy metabolism. Quantitative proteomics of rd1 retina showed early changes in calcium signaling and oxidative phosphorylation, with specific partial bypass of complex I electron transfer, which precede the onset of cell death. Concurrently, we detected alterations in central carbon metabolism, including dysregulation of components associated with glycolysis, pentose phosphate and purine biosynthesis. Ex vivo assays of oxygen consumption and transmission electron microscopy validated early and progressive mitochondrial stress and abnormalities in mitochondrial structure and function of rd1 rods. These data uncover mitochondrial over-activation and related metabolic alterations as determinants of early pathology and implicate aberrant calcium signaling as an initiator of higher mitochondrial stress. Our studies thus provide a mechanistic framework with mitochondrial damage and metabolic disruptions as early drivers of photoreceptor cell death in retinal degeneration.
Project description:Retinitis Pigmentosa (RP) is a progressive retinal degeneration in which the retina loses nearly all of its photoreceptor cells and undergoes major structural changes. Little is known regarding the role the resident glia, the Müller glia, play in the progression of the disease. Here we define gene expression changes in Müller glial cells (MGCs) from two different mouse models of RP, the retinal degeneration 1 (rd1) and rhodopsin knock-out (Rhod-ko) models. The RNA repertoire of 28 single MGCs was comprehensively profiled, and a comparison was made between MGC from wild type (WT) and mutant retinas. Two time points were chosen for analysis, one at the peak of rod photoreceptor death and one during the period of cone photoreceptor death. MGCs have been shown to respond to retinal degeneration by undergoing gliosis, a process marked by the upregulation of GFAP. In this data, many additional transcripts were found to change. These can be placed into functional clusters, such as retinal remodeling, stress response, and immune related response. It is noteworthy that a high degree of heterogeneity among the individual cells was observed, possibly due to their different spatial proximities to dying cells, and/or inherent heterogeneity among MGCs.
Project description:Retinitis pigmentosa is an inherited disease with sequential retinal degeneration of rod then cone photoreceptors leading to blindness. As in this human syndrome the rd1 mouse model carries a recessive mutation in the rod-specific cGMP phosphodiesterase beta subunit gene leading to rod followed by cone photoreceptor death. The cascade of early events leading to the induction of rod cell death through apoptosis remains unknown. We report a differential whole-genome expression profiling analysis of the wild-type and rd1 mouse retinal transcriptional program using high-density oligonucleotide microarrays with a time series experiment spanning the entire rod photoreceptor degeneration process. Among the 1252 genes found to be significantly differentially expressed, a key group of 19 loci showed distinct differences in expression early in development, suggesting that these genes of clinical interest may play a fundamental role in the induction of the rod photoreceptor degeneration.
Project description:Retinitis Pigmentosa (RP) is a progressive retinal degeneration in which the retina loses nearly all of its photoreceptor cells and undergoes major structural changes. Little is known regarding the role the resident glia, the MM-CM-<ller glia, play in the progression of the disease. Here we define gene expression changes in MM-CM-<ller glial cells (MGCs) from two different mouse models of RP, the retinal degeneration 1 (rd1) and rhodopsin knock-out (Rhod-ko) models. The RNA repertoire of 28 single MGCs was comprehensively profiled, and a comparison was made between MGC from wild type (WT) and mutant retinas. Two time points were chosen for analysis, one at the peak of rod photoreceptor death and one during the period of cone photoreceptor death. MGCs have been shown to respond to retinal degeneration by undergoing gliosis, a process marked by the upregulation of GFAP. In this data, many additional transcripts were found to change. These can be placed into functional clusters, such as retinal remodeling, stress response, and immune related response. It is noteworthy that a high degree of heterogeneity among the individual cells was observed, possibly due to their different spatial proximities to dying cells, and/or inherent heterogeneity among MGCs. Retinas were dissociated and single Muller Glial Cells were picked under a dissecting microscope using a micropipette based on their distinct morphological shape. Single cell cDNAs were generated and genome wide profiles were obtained by hybridization to Affymetrix 430 2.0 microarrays. Data was normalized using MAS5.0 software. A total of 28 Muller Glial Cells were analyzed and confirmed post hoc by expression of known marker genes.