Cellular Responses to Photoreceptor Death in therd1Mouse Model of Retinal Degeneration (original) (raw)
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Cellular responses to photoreceptor death in the rd1 mouse model of retinal degeneration
2007
Retinal degeneration is a disease that typically involves the loss of photoreceptors. Murine models have been established for such degenerations, and a variety of methods have been used to follow the progression of the disease. In the present study in situ hybridization was used to analyze gene expression responses in the different retinal cell types during the period of cone death in the rd1 mouse model. METHODS. A preliminary microarray analysis led to the selection of 169 candidate genes that might change in level of expression during degeneration. Probes corresponding to these genes were used for in situ hybridization on tissue during the period of cone death. Expression values were assigned to the intensities of in situ hybridization signals and were compared between mutant and wild-type tissue. RESULTS. During the peak of cone death, the in situ hybridization signals were typically higher in the mutant. This signal change was often true of genes with a wild-type pattern of expression in ganglion cells, bipolar cells, and/or Müller glia. In such cases, the upregulation was highest in bipolar cells and/or Müller glia. CONCLUSIONS. All retinal cell types responded during the process of retinal degeneration, as revealed by changes in gene expression. Genes that showed changes in the in situ hybridization signals during the period of cone death were typically higher in the mutant, with many of them expressed in both the ganglion cell layer and the inner nuclear layer.
Isolation of a candidate cDNA for the gene causing retinal degeneration in the rd mouse
Proceedings of the National Academy of Sciences, 1989
The inherited retinal degeneration of the rd mouse results in the exclusive loss of one cell type, the photoreceptors. We took advantage of this visual-cell loss to devise a strategy for the isolation of photoreceptor-specific cDNAs based on the use of subtractive and differential hybridizations. The resulting pool of photoreceptor-specific cDNAs was screened for a candidate cDNA for the rd gene, and a putative rd cDNA that maps to mouse chromosome 5, the chromosome to which the rd gene has been assigned, was identified. On Northern blots the candidate rd cDNA hybridizes a 3.3-kilobase RNA species from 9-to 11-day-old developing normal retina and, much more faintly, a 3.6-kb RNA species from agematched rd retina. The 0.3-kilobase difference in the size of the mRNAs hybridized suggests that a structural alteration in the gene corresponding to the candidate rd cDNA has occurred in the rd mouse. This was further supported by the detection of polymorphisms between rd/rd and +/+ mouse genomic DNA after digestion with restriction endonucleases and probing with the candidate rd cDNA. Expression of mRNAs hybridized by the candidate rd cDNA is detected in normal and diseased retinas at postnatal day 1 but the signal intensity is considerably lower in the rd retina. To our knowledge, this is the earliest molecular defect reported in the rd retina that is observed prior to any phenotypic signs of photoreceptor degeneration.
Photoreceptor Cell Death Mechanisms in Inherited Retinal Degeneration
Molecular Neurobiology, 2008
Photoreceptor cell death is the major hallmark of a group of human inherited retinal degenerations commonly referred to as retinitis pigmentosa (RP). Although the causative genetic mutations are often known, the mechanisms leading to photoreceptor degeneration remain poorly defined. Previous research work has focused on apoptosis, but recent evidence suggests that photoreceptor cell death may result primarily from non-apoptotic mechanisms independently of AP1 or p53 transcription factor activity, Bcl proteins, caspases, or cytochrome c release. This review briefly describes some animal models used for studies of retinal degeneration, with particular focus on the rd1 mouse. After outlining the major features of different cell death mechanisms in general, we then compare them with results obtained in retinal degeneration models, where photoreceptor cell death appears to be governed by, among other things, changes in cyclic nucleotide metabolism, downregulation of the transcription factor CREB, and excessive activation of calpain and PARP. Based on recent experimental evidence, we propose a putative non-apoptotic molecular pathway for photoreceptor cell death in the rd1 retina. The notion that inherited photoreceptor cell death is driven by non-apoptotic mechanisms may provide new ideas for future treatment of RP.
Investigative Ophthalmology & Visual Science
To define the nature and estimate the molecular weight range of soluble endogenous retinal trophic activities on cone photoreceptor survival in two models of cone degeneration. METHODS. Diffusible factors from dissociated retinal cell cultures of 8-day normal-sighted (C57BL/6J) mice were tested for cone-survival-promoting activity by two approaches and by using two independent photoreceptor degeneration models. In the first approach, mouse retinal cells were cultured on semipermeable membranes apposed to dissociated cultures of chick embryo retina. In the second approach, conditioned medium was collected from normal mouse retinal cultures and added to embryonic chicken retina cultures or to retinal explants obtained from 5-week retinal degeneration (rd1) mice.
Changes in gene expression associated with retinal degeneration in the rd3 mouse
Molecular Vision, 2013
To identify and characterize changes in gene expression associated with photoreceptor degeneration in the rd3 mouse model of Leber congenital amaurosis (LCA) type 12. Methods: Global genome expression profiling using microarray technology was performed on total RNA extracts from rd3 and wild-type control mouse retinas at postnatal day 21. Quantitative PCR analysis of selected transcripts was performed to validate the microarray results. Results: Functional annotation of differentially regulated genes in the rd3 mouse defined key canonical pathways, including phototransduction, glycerophospholipid metabolism, tumor necrosis factor receptor 1 signaling, and endothelin signaling. Overall, 1,140 of approximately 55,800 transcripts were differentially represented. In particular, a large percentage of the upregulated transcripts encode proteins involved in the immune response; whereas the downregulated transcripts encode proteins involved in phototransduction and lipid metabolism. Conclusions: This analysis has elucidated several candidate genes and pathways, thus providing insight into the pathogenic mechanisms underlying the photoreceptor degeneration in the rd3 mouse retina and indicating directions for future studies.
Retinal degeneration in cone photoreceptor cell-ablated transgenic mice
Molecular vision, 2000
To examine the effect of loss of cone photoreceptor cells on retinal degeneration. We previously identified a cone photoreceptor cell-specific promoter of human cone transducin a-subunit (GNAT2) gene. In this report, a minigene, Trc-Tox176, that contains the GNAT2 promoter, an attenuated diphtheria toxin A-chain gene, and an enhancer element from human interphotoreceptor retinoid-binding protein (IRBP) was used to generate coneless transgenic mice. Transgenic mice were identified by PCR and the copy number of the transgene was determined by Southern hybridization, and examined by histology. The results of immunostaining with anti-mouse GNAT2 antibodies and reverse transcription-PCR (RT-PCR) analysis with mRNA from the retinas of transgenic mice showed that cone photoreceptor cells were ablated in one of four transgenic mouse lines. The ablation of cone cells began at postnatal day 8, at the same time as the expression of endogenous GNAT2. An age-related rod degeneration was also fou...
Cell, 2001
S1 at http://www.cell.com/cgi/content/full/107/5/579/ DC1). This feature appears to be a common property of photoreceptor disorders, also holding true for rd mutations in Drosophila (Ranganathan et al., 1995) and other organisms (Semple-Rowland et al., 1998; Suber et al., ), although the reason for this selective vulnerability is poorly understood. Even in retinal diseases where an Boston, Massachusetts 02115 2 Center of Developmental Biology inner retinal phenotype is observed, such as X-linked retinoschisis, a rod-specific expression pattern of the The University of Texas Southwestern Medical Center at Dallas disease gene is seen (Reid et al., 1999). So high is this correlation between tissue specificity of expression and 5323 Harry Hines Boulevard Dallas, Texas 75235 clinical phenotype that gene expression profiles could in principle be an important tool for identification of retinal disease genes. Thus, a major limiting factor in cloning additional retinal disease genes has been the Summary lack of a full catalog of genes that are selectively expressed in photoreceptors. While approaches such as To identify the full set of genes expressed by mammasubtractive hybridization (Bascom et al., 1993; Guillonlian rods, we conducted serial analysis of gene expresneau et al., 1999) and examination of EST databases sion (SAGE) by using libraries generated from mature (Sohocki et al., 2000)
PLoS ONE, 2011
A homozygous mutation in STK38L in dogs impairs the late phase of photoreceptor development, and is followed by photoreceptor cell death (TUNEL) and proliferation (PCNA, PHH3) events that occur independently in different cells between 7-14 weeks of age. During this period, the outer nuclear layer (ONL) cell number is unchanged. The dividing cells are of photoreceptor origin, have rod opsin labeling, and do not label with markers specific for macrophages/microglia (CD18) or Mü ller cells (glutamine synthetase, PAX6). Nestin labeling is absent from the ONL although it labels the peripheral retina and ciliary marginal zone equally in normals and mutants. Cell proliferation is associated with increased cyclin A1 and LATS1 mRNA expression, but CRX protein expression is unchanged. Coincident with photoreceptor proliferation is a change in the photoreceptor population. Prior to cell death the photoreceptor mosaic is composed of L/M-and Scones , and rods. After proliferation, both cone types remain, but the majority of rods are now hybrid photoreceptors that express rod opsin and, to a lesser extent, cone S-opsin, and lack NR2E3 expression. The hybrid photoreceptors renew their outer segments diffusely, a characteristic of cones. The results indicate the capacity for terminally differentiated, albeit mutant, photoreceptors to divide with mutations in this novel retinal degeneration gene.