DNA microarray cluster analysis reveals tissue similarity and potential neuron-specific genes expressed in cranial...

Each of four cranial sensory ganglia, trigeminal, geniculate, petrosal, and nodose ganglia, contains multiple kinds of sensory neurons with different cell morphologies and neuronal properties that transmit information about sensory stimuli received peripherally. Here we analyze the complex properties of these neurons from the viewpoint of gene expression using DNA microarrays by cluster analysis. From a total of 8,740 genes, 498 genes were selected as showing tissue-dependent expression on the microarray by hierarchical cluster analysis, and their profiles indicated that, among the four sensory ganglia, the petrosal and trigeminal ganglia are intimately related. Tissue trees of 37 subclusters containing the 498 genes showed that the profiles of gene expression and the subclusters were classified into a smaller number of groups (18 groups) when information on the amounts of expression was added. In situ hybridization analysis of 21 genes selected from 13 different groups was carried out, and the gene expression patterns were classified into eight categories. The putative profiles postulated from the microarray data were essentially consistent with the patterns of expression at the cellular level as shown by in situ hybridization. In conclusion, from the overall analyses of gene expression by DNA microarray, we can identify a number of candidate genes showing neuron type-specific expression in the peripheral ganglia.