Transcriptional profiling of melanocytes from patients with vitiligo vulgaris.

Vitiligo is a complex, polygenic disorder characterized by patchy loss of skin pigmentation due to abnormal melanocyte function. Both genetic and environmental etiological factors have been proposed for vitiligo and lack of molecular markers renders difficulties to predict development and progression of the disease. Identification of dysregulated genes has the potential to unravel biological pathways involved in vitiligo pathogenesis, facilitating discovery of potential biomarkers and novel therapeutic approaches. In this study, we characterized the transcriptional profile of melanocytes from vitiligo patients. Oligonucleotide microarrays containing approximately 16,000 unique genes were used to analyse mRNA expression in melanocytes from vitiligo patients and age-matched healthy controls. In total, 859 genes were identified as differentially expressed. A substantial number of these genes were involved in (i) melanocyte development, (ii) intracellular processing and trafficking of tyrosinase gene family proteins, (iii) packing and transportation of melanosomes, (iv) cell adhesion and (v) antigen processing and presentation. In conclusion, our results show a significantly different transcription profile in melanocytes from vitiligo patients compared with controls. Several genes of potential importance for the pathogenesis and development of vitiligo were identified. Our data indicate that autoimmunity involving melanocytes may be a secondary event in vitiligo patients caused by abnormal melanocyte function.

Microarray analysis using disiloxyl 70mer oligonucleotides.

DNA microarray technology has evolved dramatically in recent years, and is now a common tool in researchers' portfolios. The scope of the technique has expanded from small-scale studies to extensive studies such as classification of disease states. Technical knowledge regarding solid phase microarrays has also increased, and the results acquired today are more reliable than those obtained just a few years ago. Nevertheless, there are various aspects of microarray analysis that could be improved. In this article we show that the proportions of full-length probes used significantly affects the results of global analyses of transcriptomes. In particular, measurements of transcripts in low abundance are more sensitive to truncated probes, which generally increase the degree of cross hybridization and loss of specific signals. In order to improve microarray analysis, we here introduce a disiloxyl purification step, which ensures that all the probes on the microarray are at full length. We demonstrate that when the features on microarrays consist of full-length probes the signal intensity is significantly increased. The overall increase in intensity enables the hybridization stringency to be increased, and thus enhance the robustness of the results.

A high-throughput strategy for protein profiling in cell microarrays using automated image analysis.

Advances in antibody production render a growing supply of affinity reagents for immunohistochemistry (IHC), and tissue microarray (TMA) technologies facilitate simultaneous analysis of protein expression in a multitude of tissues. However, collecting validated IHC data remains a bottleneck problem, as the standard method is manual microscopical analysis. Here we present a high-throughput strategy combining IHC on a recently developed cell microarray with a novel, automated image-analysis application (TMAx). The software was evaluated on 200 digital images of IHC-stained cell spots, by comparing TMAx annotation with manual annotation performed by seven human experts. A high concordance between automated and manual annotation of staining intensity and fraction of IHC-positive cells was found. In a limited study, we also investigated the possibility to assess the correlation between mRNA and protein levels, by using TMAx output results for relative protein quantification and quantitative real-time PCR for the quantification of corresponding transcript levels. In conclusion, automated analysis of immunohistochemically stained in vitro-cultured cells in a microarray format can be used for high-throughput protein profiling, and extraction of RNA from the same cell lines provides a basis for comparing transcription and protein expression on a global scale.

A human protein atlas for normal and cancer tissues based on antibody proteomics.

Antibody-based proteomics provides a powerful approach for the functional study of the human proteome involving the systematic generation of protein-specific affinity reagents. We used this strategy to construct a comprehensive, antibody-based protein atlas for expression and localization profiles in 48 normal human tissues and 20 different cancers. Here we report a new publicly available database containing, in the first version, approximately 400,000 high resolution images corresponding to more than 700 antibodies toward human proteins. Each image has been annotated by a certified pathologist to provide a knowledge base for functional studies and to allow queries about protein profiles in normal and disease tissues. Our results suggest it should be possible to extend this analysis to the majority of all human proteins thus providing a valuable tool for medical and biological research.