Molecular Profiling of Small and Large Retinal Ganglion Cells
ABSTRACT: Different sub-types of ganglion cells existing in mammalian retinas possessing distinct function in processing the visual information. In primates, RGC are commonly divided into midget cells, which are relatively small, and parasol cells, with a larger soma size. Rodents also possess morphologically distinct populations, but their physiological properties are less characterized. The two types of mammalian RGCs differ in their response to pathological conditions such as retinal ischemia, diabetic retinopathy and glaucoma. In this work, we compared gene expression profiles of large (LRGCs) and small (SRGCs) ganglion cells isolated from rat retina in attempt to identify molecular determinants underlying differences in function and tolerance to stress. Keywords: comparative hybridization Overall design: Rat RGCs retrogradely labeled with 4DI-10ASP were purified from freshly dissected retinas and subjected to fluorescent-activated cell sorting (FACS) in order to separate the SRGC and LRGC sub-populations. Actinomycin D was added to prevent new transcription during experimental procedures. Purified cells were used for RNA isolation. Following two rounds of linear amplification aRNA probes were hybridized with two-color Agilent Rat Genomic Oligo Arrays. We utilized the dye swap experimental design to eliminate the dye bias effects and make data from different experiments available for the cross-comparison.
INSTRUMENT(S): Agilent-013162 Whole Rat Genome Microarray G4131A (Feature Number version)
Project description:Different sub-types of ganglion cells existing in mammalian retinas possessing distinct function in processing the visual information. In primates, RGC are commonly divided into midget cells, which are relatively small, and parasol cells, with a larger soma size. Rodents also possess morphologically distinct populations, but their physiological properties are less characterized. The two types of mammalian RGCs differ in their response to pathological conditions such as retinal ischemia, diabetic retinopathy and glaucoma. In this work, we compared gene expression profiles of large (LRGCs) and small (SRGCs) ganglion cells isolated from rat retina in attempt to identify molecular determinants underlying differences in function and tolerance to stress. Experiment Overall Design: Rat RGCs retrogradely labeled with 4DI-10ASP were purified from freshly dissected retinas and subjected to fluorescent-activated cell sorting (FACS) in order to separate the SRGC and LRGC sub-populations. Actinomycin D was added to prevent new transcription during experimental procedures. Purified cells were used for RNA isolation. Following two rounds of linear amplification aRNA probes were hybridized with two-color Agilent Rat Genomic Oligo Arrays. We utilized the dye swap experimental design to eliminate the dye bias effects and make data from different experiments available for the cross-comparison.
Project description:At least 30 types of retinal ganglion cell (RGC) send distinct messages through the optic nerve to the brain. Strategies for promoting regeneration of RGC axons following injury act on only some of these types. Here we tested the hypothesis that over-expressing developmentally important transcription factors in adult RGCs could reprogram them to a “youthful” growth-competent state and promote regeneration of other types. From a screen of transcription factors expressed by developing RGCs, we found one, Sox11, that induced substantial axon regeneration. Transcriptome profiling confirmed that Sox11 activates genes involved in cytoskeletal remodeling and axon growth. Remarkably, alpha-RGCs, which preferentially regenerate following treatments such as PTEN deletion, were killed by Sox 11. Thus, Sox 11 promotes regeneration of non-alpha RGCs, which are refractory to PTEN. We conclude that Sox11 can reprogram adult RGCs to a growth-competent state and that different growth-promoting interventions act on distinct neuronal types. Overall design: We compared transcriptomes of retinal ganglion cells between AAV-Control retinas, and retinas treated with AAV-Sox11 overexpression. We then performed optic nerve crush, and 3 days later purified RGCs using FACS. RGCs were marked with Thy1-PE-Cy7 antibody and with live/dead cell staining. We performed sample preparations in full triplicate, and in each replicate we always performed Control and Sox11 on the same day, in alternating order.
Project description:The retinal projection neurons, retinal ganglion cells (RGCs), can be categorized into distinct morphological and functional subtypes and by the laterality of their projections. Here, we used a new method for purifying the sparse population of ipsilaterally projecting RGCs in mouse retina from their contralaterally-projecting counterparts during embryonic development through rapid retrograde labeling followed by fluorescence-activated cell sorting (FACS). Through microarray analysis, we have uncovered the distinct molecular signatures that define and distinguish ipsilateral and contralateral RGCs during the critical period of axonal outgrowth and decussation, with over three hundred genes differentially experienced within these two cell populations. Amongst the genes upregulated in ipsilateral RGCs are many that are known to be expresed in progenitors cells and mark “immaturity," including Math5 (Atoh7), Sox2, and cyclin D2. Many of these differentially regulated genes were subsequently validated via in vivo expression analysis. Thus, the molecular signatures of ipsilateral and contralateral RGCs and the mechanisms that regulate their differentiation are more diverse than previously expected. Overall design: Embryonic day (E16) mouse RGCs were labeled with tetramethylrhodamine-conjugated dextran from the optic tract ex vivo. Ipsilateral and contralateral retinas from 2 litters of embryos were dissected 2 hours following dye application and subsequently dissociated using papain. Rhodamine-positive RGCs were isolated using fluorescence-activated cell sorting (FACS) for microarray studies.
Project description:A growing body of evidence suggests that the vasoactive peptides endothelins (ETs) and their receptors (primarily the ETB receptor) are contributors to neurodegeneration in glaucoma. However, ET’s actions in retinal ganglion cells (RGCs) are not fully understood. The purpose of this study was to determine ETs effects on gene expression in primary RGCs. Primary RGCs treated with 100nM of ET-1, ET-2 or ET-3 for 24 hours was used as cell model to investigation the role of endothelins in gene expression. Overall design: Primary RGCs isolated from rat pups were treated with 100nM of ET-1, ET-2 or ET-3 for 24 hours. Total RNA was extracted followed by cDNA synthesis. Changes in gene expression in RGCs was detected using Affymetrix Rat Genome 230 2.0 microarray and categorized by DAVID analysis.
Project description:Adult mammalian CNS neurons undergo a developmental switch in intrinsic axon growth ability associated with their failure to regenerate axons after injury. Krüppel-like transcription factors (KLF) regulate intrinsic axon growth ability, but signaling regulation upstream and downstream is poorly understood. Here we find that suppressing expression of KLF9, an axon growth suppressor normally upregulated 250-fold in retinal ganglion cell (RGC) development, promotes long-distance optic nerve regeneration in vivo. We identify a novel binding partner, MAPK10/JNK3, critical for KLF9’s axon growth suppressive activity. Additionally, by screening genes regulated by KLFs in RGCs, we identify dual-specificity phosphatase 14 (Dusp14) as key to limiting axon growth and regenerative ability downstream of KLF9, associated with its dephosphorylation of MAPKs critical to neurotrophic signaling of RGC axon elongation. These results now link intrinsic and extrinsic regulation of axon growth and suggest new therapeutic strategies to promote axon regeneration in the adult CNS. Overall design: RGCs from early postnatal rats were purified and KLF9, -16, -7, and -11 genes and control, FLAG-tagged mCherry gene were transduced using lentivirus. RNA was then extracted using RNEasy (Qiagen) and processed for hybridization onto Affymetrix Rat Genome 230 2.0 Arrays.
Project description:Diabetic retinopathy is one of the leading causes of blindness in diabetic patients. Emerging evidence suggests that retinal neurodegeneration is an early event in the pathogenesis of diabetic retinopathy, but the underlying causes of neuronal loss are unknown. To unravel potential mechanisms underlying early retinal neurodegeneration in diabetic retinopathy, a gene expression profiling study was undertaken to compare the gene expression in retinas of 8-week db/db diabetic mice with that of lean non-diabetic littermates. Retinas were obtained from 8-week db/db diabetic mice and age-matched lean non-diabetic controls. Total RNA was extracted and processed for being hybridized onto affymetrix DNA microarrays.
Project description:Rbfox1 is a splicing regulator that has been associated with various neurological conditions such as autism spectrum disorder, mental retardation, epilepsy, attention-deficit/hyperactivity disorder, and schizophrenia. We show that in adult rodent retinas, Rbfox1 is expressed in all types of retinal ganglion cells (RGCs) as well as in certain subsets of amacrine cells (ACs) within the inner nuclear and ganglion cell layers. In developing retinas, Rbfox1 can be detected as early as E12. At that age, Rbfox1 is localized in the cytoplasm of differentiated RGCs. Between P0 and P5, strong expression of Rbfox1 in the inner plexiform layer was observed. This coincided with switching of Rbfox1 localization in RGC somas from cytoplasmic to a predominantly nuclear. Dynamic changes in Rbfox1 expression during first 10 postnatal days are correlated with the stage II spontaneous retinal waves of excitation, which in mice begins around the time of birth and continues for as long as two weeks. By P10, dendritic staining of Rbfox1 was dramatically reduced and remained so in the fully developed retina. In Rbfox1 knockout (KO) animals no detectable changes in retinal gross morphology were observed two months after Rbfox1 downregulation. However, the visual cliff test revealed marked abnormalities of depth perception of these animals. Retinal transcriptome analysis of Rbfox1 KO mice identified a number of genes that are involved in establishing neural circuits and synaptic transmission, including Vamp1, Vamp2, Snap25, Trak2, and Slc1A7, suggesting a role of Rbfox1 in the regulation of genes that facilitate AC and RGC synaptic communication. Overall design: Retinal RNRetinal RNA-seq analysis was performed with 3 biological replicates representing Rbfox1-/- and 3 biological replicates representing control animals to identify differentially expressed and alternatively spliced genes. Rbfox1-/- animals were generated by crossing Rbfox1loxP/loxP(B6.129S2-Rbfox1tm1.1Dblk/J) mice with Tg(UBC-cre/ERT2)1Ejb mice. Cre expression was induced with tamoxifen in adult homozygous Rbfox1loxP/loxP; UBC-Cre+/- mice. Mice used in this study were maintained on the C57BL/6J background.
Project description:Visual information is conveyed from the eye to the brain by distinct types of Retinal Ganglion Cells (RGCs). It is largely unknown how RGCs acquire their defining morphological and physiological features and connect to upstream and downstream synaptic partners. The three Brn3/Pou4f transcription factors (TFs) participate in the combinatorial code for RGC type specification but their exact molecular roles are still unclear. We use deep sequencing to define (i) transcriptomes of Brn3a and/or Brn3b positive RGCs, (ii) Brn3a and/or Brn3b dependent RGC transcripts and (iii) transcriptomes of retinorecipient areas of the brain at developmental stages relevant for axon guidance, dendrite formation and synaptogenesis. We reveal a combinatorial code of transcription factors, adhesion molecules and determinants of neuronal morphology that are differentially expressed in specific RGC populations and selectively regulated by Brn3a and/or Brn3b. This comprehensive molecular code provides a basis for understanding neuronal cell type specification in RGCs. Overall design: For retinal ganglion cells (RGCs) alkaline phosphatase (AP) positive and negative cells from Brn3aAP/WT, Brn3aAP/KO, Brn3bAP/WT, and Brn3bAP/KO from dissociated mouse retina at embryonic day 15 and post-natal day 3 were isolated by magnetic beads coupled to anti-AP mouse monoclonal antibodies. Lateral geniculate nucleus (LGN), superior colliculus (SC) and pretectal area (PTA) retinorecipient nuclei from wild type post-natal day 3 mice were visualized by anterograde tracing, microdissected, and processed for RNA isolation. Total RNA was extracted by Qiagen RNeasy using on-column DNase treatment (Qiagen) and analyzed by 2100 Bioanalyzer (Agilent Technologies Genomics). High quality of total RNA (RIN: >8.0) was subjected to sequencing library construction using 20 ng of total RNA as input. Libraries were constructed using a stranded modification of the Illumina TruSeq mRNA (Brooks, et al. Meth Mol Biol 2012). Each RGC library was single-end sequenced in an independent lane of a GAIIx at a length of 76 bases. Brain samples were paired-end sequenced to 125 bases on an Illumina HiSeq2500. Fastq files were generated from reads passing chastity filter.
Project description:Photoreceptor disorders are collectively known as retinal degeneration (RD), and include retinitis pigmentosa (RP), cone-rod dystrophy and age related macular degeneration (AMD). These disorders are largely genetic in origin; individual mutations in any one of >200 genes cause RD, making mutation specific therapies prohibitively expensive. A better treatment plan, particularly for late stage disease, may involve stem cell transplants into the photoreceptor or ganglion cell layers of the retina. Stem cells from young mouse retinas can be transplanted, and can form photoreceptors in adult retinas. These cells can be grown in tissue culture, but can no longer form photoreceptors. We have used microarrays to investigate differences in gene expression between cultured retinal progenitor cells (RPCs) that have lost photoreceptor potential, postnatal day 1 (pn1) retinas and the postnatal day 5 (pn5) retinas that contain transplantable photoreceptors. We have also compared FACS sorted Rho-eGFP expressing rod photoreceptors from pn5 retinas with Rho-eGFP negative cells from the same retinas. We have identified over 300 genes upregulated in rod photoreceptor development in multiple comparisons, 37 of which have been previously identified as causative of retinal disease when mutated. It is anticipated that this research should bring us closer to growing photoreceptors in culture and therefore better treatments for RD. This dataset is also a resource for those seeking to identify novel retinopathy genes in RD patients. We extracted whole retinas from postnatal day 1 (Pn1) and postnatal day 5 (Pn5) mice, and compared them with cultured RPCs derived from pn5 retinas, using Affymetrix mouse 430A_2 arrays. We also extracted cells from Rho-eGFP Pn5 retinas and FACS sorted them. GFP+ve cells represent immature rod photoreceptors, as they express the Rho-eGFP fusion protein, which is only expressed in rods. GFP-ve cells represent all other retinal neurons. These samples were amplified and compared using Affymetrix mouse 430A_2arrays, by Source Biosciences GMBH, Berlin, Germany. Results from immature rods were then compared with those from other retinal neurons, while results from whole Pn5 retinas were compared with Pn1 retinas (which don't yet express rod specific genes), and RPCs, which are glial precursors. RPCs were also compared with Pn1 retinas. Genes which showed changed expression profiles in at least 3/4 of comparisons were prioritised for further investigation.
Project description:In mammalian albinism, disrupted melanogenesis in the retinal pigment epithelium (RPE) is associated with fewer retinal ganglion cells (RGCs) projecting ipsilaterally to the brain, resulting in numerous abnormalities in the retina and visual pathway, especially binocular vision. To further understand the molecular link between disrupted RPE and a reduced ipsilateral RGC projection in albinism, we compared gene expression in the embryonic albino and pigmented mouse RPE. Overall design: Embryonic day (E) 13.5 mouse RPE was detached from the eyes. Three biological replicates were analyzed. For each biological replicate (pigmented and albino), RPE tissues of three - four littermate embryos were pooled.