Unknown,Transcriptomics,Genomics,Proteomics

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Transcription profiling of zebrafish embryonic retinal pigment epithelium in vivo

ABSTRACT: Eye development and photoreceptor maintenance requires the retinal pigment epithelium (RPE), a thin layer of cells that underlies the neural retina. Despite its importance, RPE development has not been studied by a genomic approach. A microarray expression profiling methodology was established in this study for studying RPE development. The intact retina with RPE attached was dissected from developing embryos, and differentially expressed genes in RPE were inferred by comparing the dissected tissues with retinas without RPE using microarray and statistical analyses. We found 8810 probesets to be significantly expressed in RPE at 52 hours post-fertilization (hpf), of which 1443 might have biologically meaningful expression levels. Further, 78 and 988 probesets were found to be significantly over- or under-expressed in RPE respectively compared to retina. Also, 79.2% (38/48) of the known over-expressed probesets have been independently validated as RPE-related transcripts. The results strongly suggest that this methodology can obtain in vivo RPE specific gene expression from the zebrafish embryos and identify novel RPE markers. Experiment Overall Design: The gene expression levels of three independent replicates of retina with RPE attached consisting of ten samples each at 52hpf (WRR52) were compared with three independent pure retinal samples consisting of ten retinas each at 52hpf (WR52). The yield-adjusted WR52 expression values were assumed to be equivalent to the retinal contribution in WRR52 samples and deducted from WRR52 expression values to obtain estimations of RPE gene expression at 52hpf (RPE52). Differential gene expressions between RPE and retina were inferred by comparing the RPE52 estimates and WR52 expression values.

ORGANISM(S): Danio rerio

SUBMITTER: Yuk Fai Leung

PROVIDER: E-GEOD-5048 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Gene expression profiling of zebrafish embryonic retinal pigment epithelium in vivo.

Leung Yuk Fai YF Ma Ping P Dowling John E JE

Investigative ophthalmology & visual science 20070201 2

<h4>Purpose</h4>Eye development and photoreceptor maintenance is dependent on the retinal pigment epithelium (RPE), a thin layer of cells that underlies the neural retina. Despite its importance, development of RPE has not been studied by a genomic approach. In this study, a microarray expression-profiling methodology was established for studying RPE development.<h4>Methods</h4>The intact retina with RPE attached was dissected from developing embryos, and differentially expressed genes in RPE we ...[more]

PMID: 17251491

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Project description:Retinal cells are specified in a zebrafish recessive mutant called young (yng) but they fail to terminally differentiate; i.e. extend neurites and make synaptic contacts. A point mutation in a brahma-related gene 1 (brg1) is responsible for this phenotype. In this microarray study, a three-factor factorial design was utilized to investigate the effects of 1) mutation, 2) change in time (36 vs. 52hpf), and 3) change in tissue (retina vs. whole embryos), and their interactions on gene expression. Significant probesets were inferred by using both specific contrasts of the fitted Analysis of Variance (ANOVA) models and a corresponding 2-fold expression cutoff. The probesets were grouped into three broad categories: 1) Brg1-regulated retinal differentiation genes (731 probsets), 2) Retinal specific genes but independent of Brg1 regulation (3038 probesets) and 3) Genes regulated by Brg1 but outside the retina (107 probesets). Four gene groups/pathways including neurite outgrowth regulators, Delta-Notch signalling molecules, Irx family members and specific cell cycle regulators were identified in the first group, and their relevance for retinal differentiation functionally validated. This study demonstrates that an approach such as ours can identify relevant genes and pathways involved in retinal development as well as the development of other tissues at the same time. Experiment Overall Design: The gene expression levels of three independent replicates of retina consisting of ten samples each at 36 and 52hpf retinas from WT (WR36 & WR52) and yng (YR36 & YR52) larvae, and stage-matched whole embryos: WT at 36hpf (WA36), WT at 52hpf (WA52), yng at 36hpf (YA36), and yng at 52hpf (YA52) were measured by Affymetrix Zebrafish Whole Genome Arrays. We analyzed the effects of these factors on gene expression levels: 1) mutation (M), 2) tissue (R), and 3) time (T). Each of these factors have two levels: mutant and WT (M); retinas and whole body (R); and 36 and 52 hpf (T). As a result, there are totally eight conditions for all the comparisons and the design is called a 2x2x2 factorial design. The aim of a factorial analysis is to delineate the effects of each factor and their combinations (interaction) on gene expression. The overall analysis strategy is to first fit a full Analysis of Variance (ANOVA) model with all possible main effects (T, M, R) and their interactions (T*M, M*R, R*M, T*M*R) to the gene expression data for each probeset. The estimates of the model are obtained through a maximum likelihood estimation method. Then a backward elimination strategy is used to remove insignificant main effects and interactions to get the most parsimonious models. Finally, a group of contrasts and their corresponding fold changes are used to infer whether that probeset is significantly associated with a particular biological process.

Project description:Purpose: The purpose of this study was to develop a framework for analyzing RPE expression profiles from zebrafish eye mutants. Methods: The fish model we used was smarca4 (SWI/SNF related, matrix associated, actin dependent regulator of chromatin, subfamily a, member 4), a retinal dystrophic mutant that the retinal phenotype and expression profiles were previously characterized. Histological and Affymetrix GeneChip analyses were conducted to define the RPE defects and underlying differential expression respectively. Results: Histological analysis indicates that smarca4 RPE was formed but its differentiation was abnormal. In particular, ultra-structural analysis of smarca4 RPE by transmission electron microscopy showed a number of defects in melanogenesis, suggesting that the cytoskeletal dynamics was impaired. To compare the expression profile of normal wild-type (WT) and smarca4 RPE, their retinas and RPE-attached retinas were microdissected and the gene expression values of these tissues measured by Affymetrix GeneChip analysis. The RPE expression values were then estimated from these samples using an approach previously established by us. A factorial analysis was conducted using the expression values of RPE, retinal as well as the whole-embryo samples. Specific rules (contrasts) were built using the coefficients of the resulting fitted model to select for three groups of genes: 1) Smarca4-regulated RPE genes, 2) Smarca4-regulated retinal genes, and 3) Smarca4-regulated RPE genes that are not differentially expressed in the retina. The latter group consists of 39 genes that are highly related to cytoskeletal dynamics, melanogenesis, paracrine and intracellular signal transduction. Conclusions: Our analytical framework can potentially identify genes in zebrafish mutants that both retina and RPE are affected by the underlying mutation. The gene expression levels of three independent replicates of WT whole embryos (WA52), WT retinas (WR52), WT RPE-attached retinas (WRR52), smarca4/yng retinas (YR52), smarca4 RPE-attached retinas (YRR52) and smarca4 whole embryos (YA52) were measured by Affymetrix Zebrafish Whole Genome Arrays. All samples were collected at 52 hpf. The probe-level data of these sample groups were background adjusted, normalized and summarized by a robust multiarray average (RMA) algorithm. RPE expression values were estimated from the comparison between the retinal and RPE-attached retinal samples of the same genotype based on a method we previously developed (Leung et al., Invest Ophthalmol Vis Sci. 2007; 48:881). Then, a 3x2 factorial design was used to analyze the expression values of three kinds of tissue (T): whole embryo, retina and RPE in two kinds of mutation (M) background: WT and smarca4. Using the coefficients from the fitted models, contrasts were built to identify candidate genes that fulfilled specific criteria. The false discovery rate (FDR) q-value cutoff for a contrast was 0.001. Several contrasts were ultimately combined to allow for selection of genes that were regulated by Smarca4 in the retina and RPE. These include 1) Smarca4-regulated RPE genes, 2) Smarca4-regulated retinal genes, and 3) Smarca4-regulated RPE genes that are not differentially expressed in the retina.

Project description:<p>Proper spatial differentiation of retinal cell types is necessary for normal human vision. Many retinal diseases, such as Best disease and male germ cell associated kinase (MAK)-associated retinitis pigmentosa, preferentially affect distinct topographic regions of the retina. While much is known about the distribution of cell types in the retina, the distribution of molecular components across the posterior pole of the eye has not been well-studied. To investigate regional difference in molecular composition of ocular tissues, we assessed differential gene expression across the temporal, macular, and nasal retina and retinal pigment epithelium (RPE)/choroid of human eyes using RNA-Seq. RNA from temporal, macular, and nasal retina and RPE/choroid from four human donor eyes was extracted, poly-A selected, fragmented, and sequenced as 100 bp read pairs. Digital read files were mapped to the human genome and analyzed for differential expression using the Tuxedo software suite. Retina and RPE/choroid samples were clearly distinguishable at the transcriptome level. Numerous transcription factors were differentially expressed between regions of the retina and RPE/choroid. Photoreceptor-specific genes were enriched in the peripheral samples, while ganglion cell and amacrine cell genes were enriched in the macula. Within the RPE/choroid, RPE-specific genes were upregulated at the periphery while endothelium associated genes were upregulated in the macula. Consistent with previous studies, BEST1 expression was lower in macular than extramacular regions. The MAK gene was expressed at lower levels in macula than in extramacular regions, but did not exhibit a significant difference between nasal and temporal retina. The regional molecular distinction is greatest between macula and periphery and decreases between different peripheral regions within a tissue. Datasets such as these can be used to prioritize candidate genes for possible involvement in retinal diseases with regional phenotypes. </p> <p>Reprinted from <a href="https://www.ncbi.nlm.nih.gov/pubmed/?term=25446321">Whitmore, S.S., Wagner, A.H., DeLuca, A.P., Drack, A.V., Stone, E.M., Tucker, B.A., Zeng, S., Braun, T.A., Mullins, R.F., Scheetz, T.E., 2014. Transcriptomic analysis across nasal, temporal, and macular regions of human neural retina and RPE/choroid by RNA-Seq. Experimental Eye Research</a>. Used under <a href="http://creativecommons.org/licenses/by-nc-sa/3.0/">Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported </a>license.</p> <p>Additional RNA sequencing was performed on temporal, macular, nasal, inferior, and superior retina from a fifth subject and is included in this dataset. See original publication for details.</p>

Project description:Purpose: The aim of this study was to give a comprehensive overview on spatial distribution of gene expression in the adult mouse retina and integrate this information into existing retinal gene expression databases. Methods: Total RNA was collected by laser capture microdissection from the ganglion cell layer, inner nuclear layer, photoreceptors and the retinal pigmented epithelium of adult mice and was analyzed by oligonucleotide microarrays. The results were validated by quantitative real time PCR and in situ hybridization. Results: The applied method resulted in good separation of cells of different retinal layers. The spatial distribution of gene expression was determined on a global scale in the retina and the RPE. Our results show good correlation with previously reported retinal gene expression and describe genes not yet characterized in the context of the retina. Conclusions: The complexity of the vertebrate retina makes it necessary to determine not only temporal but spatial distributions of gene expression .Our work expands the already significant but still incomplete knowledge of retinal gene expression and hopefully facilitates functional characterization of key factors of retinal development and maintenance. Laser capture microdissected regions of the adult mouse neuronal retina and retinal pigmented epithelium were subjected to microarray analysis. 5 conditions were investigated: ganglion cell layer (GCL, 3 biological replicates), innner nuclear layer (INL, 3 biological replicates), photoreceptor layer from Blk6 (PR-WT, 3 biological replicates) and NrlKO animals (PR-Nrl, 2 biological replicates) and retinal pigmented epithelium (RPE, 1 biological replicate). All samples are co-hybridized with a reference sample (retina). 2 or 3 technical replicates were used for each biological sample. technical replicate - labeled-extract: GC1-1, GC1-2, GC1-3 technical replicate - labeled-extract: GC2-1, GC2-2, GC2-3 technical replicate - labeled-extract: GCpool-1, GCpool-2, GCpool-3 technical replicate - labeled-extract: INL1-1, INL1-2, INL1-3 technical replicate - labeled-extract: INL2-1, INL2-2, INL2-3 technical replicate - labeled-extract: INLpool-1, INLpool-2, INLpool-3 technical replicate - labeled-extract: PR-Nrl1-1, PR-Nrl1-2 technical replicate - labeled-extract: PR-Nrl2-1, PR-Nrl2-2, PR-Nrl2-3 technical replicate - labeled-extract: PR-WT1-1, PR-WT1-2, PR-WT1-3 technical replicate - labeled-extract: PR-WT2-1, PR-WT2-2, PR-WT2-3 technical replicate - labeled-extract: PR-WTpool-1, PR-WTpool-2, PR-WTpool-3 technical replicate - labeled-extract: RPE-1, RPE-2, RPE-3