Project description:The retinal pigment epithelial (RPE) cell line ARPE-19 provides a widely-used alternative to native RPE. However, retention of the native RPE phenotype becomes problematic after multiple passages. We wished to determine if suitable culture conditions and differentiation could restore RPE-appropriate gene expression to ARPE-19. ARPE-19 cells at passages p9 to p12, grown in DMEM containing high glucose and pyruvate with 1% fetal bovine serum, were differentiated for up to 4 months. Using RNA-Seq, we compared the transcriptome of ARPE-19 cells kept in long-term culture with those cultured for 4 days. The 4 month cells developed the classic native RPE phenotype with heavy pigmentation. RNA-Seq analysis provided a comprehensive view of the relative abundance and differential expression of genes in the 4 month cells. Of the 16,757 genes with detectable signals, nearly 2435 genes were upregulated, and 931 genes were down-regulated with a fold change differences of 2 or more. Genes characteristic of RPE, including RPE65, RDH5 and RDH10, were greatly increased in ARPE-19 cells maintained at confluence for 4 months. Comparison with microarray data sets from human primary cell lines revealed important overall similarities in expression of "signature" genes. The results of this study demonstrate that ARPE-19 cells can express genes specific to native human RPE cells when appropriately cultured, and thus, can provide a relevant system to study differentiated cellular functions of RPE in vitro.
Project description:I. Exp Design 1. Type of experiment: Comparison of native versus cultured RPE cells 2. Experimental factors: Native RPE versus ARPE-19 cells grown on different matrices 3. How many hybridizations in exp: 21 4. If a common reference used for all the hybs: no 5. Quality control steps: three independent arrays for each condition 6. Description: The expression profile of ARPE-19 cells grown on different matrices were compared to morphologically normal native macular RPE cells that were laser capture microdissected from 3 donors. II. Samples used, extract prep, and labeling 1. Biosource: Human donor globes from NDRI (63, 71, 74 years old) and ARPE-19 cells. 2. Manipulations: Human donor globes were cryopreserved, and morphologically normal RPE cells from the macula were laser capture micodissected. ARPE-19 cells were grown on different matrices (plastic, Matrigel, collagen I, collagen IV, laminin, and fibronectin). 3. Extract preparation: Total RNA from cells were extracted with the RNeasy kit (Qiagen) using the manufacturerâs instructions. 4. Labeling protocol: Total RNA from cells was reverse transcribed with 33P-dCTP and 33P-dATP, and second strand cDNA was labeled with 33P-dCTP and 33P-dATP. 5. No external controls were added. III. Hybridization procedures and parameters 1. Sample, array type, batch and serial # used 2. Hybridization protocol: Hybridization was carried out using the manufacturerâs recommendations. Arrays were prehybridized with Microhyb solution containing denatured Cot-1 DNA and poly dA at 42oC for two hours. Hybridization was carried out at 42oC overnight using a hybridization oven set at 8-10 rpm. Arrays were washed twice at 50oC for 20 minutes using 2x SSC, 1%SDS and once at room temperature for 15 minutes using 0.5x SSC, 1%SDS. IV. Measurement data and specifications of data processing 1,2. Arrays were exposed to a phosphorimaging screen for 3 days and scanned at 50 mm resolution with a BioRad FX Pro-Plus phosphorimager. TIFF images from the phosphorimager were exported into ResGen Pathways 3 software for analysis. 3. Data processing: A gene was expressed if its background subtracted intensity was greater than 1.4 fold background. The data were normalized using a simple global scaling procedure, and Cluster/Treeview and Statistical Analysis of Microarrays (SAM version 1.12) programs were used for analysis.
Project description:Description I. Exp Design 1. Type of experiment: Comparison of native versus cultured RPE cells 2. Experimental factors: Native RPE versus ARPE-19 cells grown in different culture conditions 3. How many hybridizations in exp: 20 4. If a common reference used for all the hybs: no 5. Quality control steps: three independent arrays for each condition, and five different donor globes for native RPE 6. Description: The expression profile of ARPE-19 cells grown under different culture conditions were compared to morphologically normal native macular RPE cells that were laser capture microdissected from 5 donors. II. Samples used, extract prep, and labeling 1. Biosource: Human donor globes from NDRI and Sierra Eye and Tissue Bank, and ARPE-19 cells. 2. Manipulations: Human donor globes were cryopreserved, and morphologically normal RPE cells from the macula were laser capture micodissected. ARPE-19 cells were grown on different matrices (subconfluent culture density in presence of serum, confluent culture density in presence of serum, confluent culture density with serum withdrawn medium, differentiated (grown for 2.5 months) in serum, and differentiated (grown for 2.5 months) and then serum withdrawn medium). 3. Extract preparation: Total RNA from cells were extracted with the RNeasy kit (Qiagen) using the manufacturer's instructions. 4. Labeling protocol: Total RNA from cells was reverse transcribed with 33P-dCTP and 33P-dATP, and second strand cDNA was labeled with 33P-dCTP and 33P-dATP. 5. No external controls were added. III. Hybridization procedures and parameters 1. Sample, array type, batch and serial # used 2. Hybridization protocol: Hybridization was carried out using the manufacturer's recommendations. Arrays were prehybridized with Microhyb solution containing denatured Cot-1 DNA and poly dA at 42oC for two hours. Hybridization was carried out at 42oC overnight using a hybridization oven set at 8-10 rpm. Arrays were washed twice at 50oC for 20 minutes using 2x SSC, 1%SDS and once at room temperature for 15 minutes using 0.5x SSC, 1%SDS. IV. Measurement data and specifications of data processing 1,2. Arrays were exposed to a phosphorimaging screen for 3 days and scanned at 50 mm resolution with a BioRad FX Pro-Plus phosphorimager. TIFF images from the phosphorimager were exported into ResGen Pathways 3 software for analysis. 3. Data processing: A gene was expressed if its background subtracted intensity was greater than 1.4 fold background. The data were normalized using a simple global scaling procedure, and Cluster/Treeview and Statistical Analysis of Microarrays (SAM version 1.12) programs were used for analysis.
Project description:Gene expression profiling of immortalized human mesenchymal stem cells with hTERT/E6/E7 transfected MSCs. hTERT may change gene expression in MSCs. Goal was to determine the gene expressions of immortalized MSCs.
Project description:Kynureninase is a member of a large family of catalytically diverse but structurally homologous pyridoxal 5'-phosphate (PLP) dependent enzymes known as the aspartate aminotransferase superfamily or alpha-family. The Homo sapiens and other eukaryotic constitutive kynureninases preferentially catalyze the hydrolytic cleavage of 3-hydroxy-l-kynurenine to produce 3-hydroxyanthranilate and l-alanine, while l-kynurenine is the substrate of many prokaryotic inducible kynureninases. The human enzyme was cloned with an N-terminal hexahistidine tag, expressed, and purified from a bacterial expression system using Ni metal ion affinity chromatography. Kinetic characterization of the recombinant enzyme reveals classic Michaelis-Menten behavior, with a Km of 28.3 +/- 1.9 microM and a specific activity of 1.75 micromol min-1 mg-1 for 3-hydroxy-dl-kynurenine. Crystals of recombinant kynureninase that diffracted to 2.0 A were obtained, and the atomic structure of the PLP-bound holoenzyme was determined by molecular replacement using the Pseudomonas fluorescens kynureninase structure (PDB entry 1qz9) as the phasing model. A structural superposition with the P. fluorescens kynureninase revealed that these two structures resemble the "open" and "closed" conformations of aspartate aminotransferase. The comparison illustrates the dynamic nature of these proteins' small domains and reveals a role for Arg-434 similar to its role in other AAT alpha-family members. Docking of 3-hydroxy-l-kynurenine into the human kynureninase active site suggests that Asn-333 and His-102 are involved in substrate binding and molecular discrimination between inducible and constitutive kynureninase substrates.
Project description:Transcriptional profiling of human mesenchymal stem cells comparing normoxic MSCs cells with hypoxic MSCs cells. Hypoxia may inhibit senescence of MSCs during expansion. Goal was to determine the effects of hypoxia on global MSCs gene expression.