Abstract
Abstract: :
Purpose: To examine gene expression levels in the human lens epithelium using a microarray incorporating transcripts representative of most human genes. Methods: Human lenses from unidentifiable cadaver donors were obtained from tissue banks. Total RNA was isolated from epithelium–equatorial anterior fiber samples. After confirming RNA purity and integrity according to 260/280 nm ratios and Agilent biochip 28S/18S ratios, two independent pools derived from 8 donors were subjected to transcript profiling using Affymetrix HG–U133 Plus 2.0 GeneChip microarrays (∼ 54,675 probe sets representing essentially the full human genome). Data and cluster analyses were performed using Affymetrix Microarray Suite 5.0 (MAS5) and GeneSpring software. A set of connexin primers was used in real–time PCR to validate the gene expression levels identified by microarray analysis. Results: MAS5 identified the expression of over 25,000 transcripts (equivalent to ∼15,000 genes). Of those, 10,822 transcript displayed average signal intensities (SIs) exceeding 1% of the maximal SI (SImax; SI for beta B2 crystallin). Real time PCR indicated that these SIs are valid measures of relative gene expression levels. Clustering of the transcripts within all GO functional categories (GOCharts; DAVID GO database; NIAID), revealed that the lens expressed abundant levels of physiological processes genes (44.2 % of the 10,822 gene set and 32.2 % of all the physiological process genes represented in the HG–U133 Plus 2.0 array, respectively). Other highly represented gene types were those associated with cell components (40.9 % and 30.5 %), binding (32.1 % and 24.9 %), cellular processes (25.2 % and 21.1 %), catalytic activity (21.3 % and 15.8 %), transporter activity (7% and 5.2 % ), signal transducer activity (5.4 % and 7.2 %), development (5.2 % and 5.6 %) and transcription regulator activity (4.9 % and 4.4%). Conclusions: This microarray study provides the opportunity for extensive global gene analysis of the surface of the human lens.
Keywords: gene microarray • gene/expression • cataract