Gene discovery and expression profiling in porcine Peyerʹs patch

Peyerʹs patches of the intestinal mucosa are essential for host defense and immune regulation in the enteric system. To better understand molecular mechanisms of Peyerʹs patch function, we have screened for differentially expressed genes specific to Peyerʹs patch. cDNA libraries were created from normal Peyerʹs patch, immune stimulated Peyerʹs patch, and pooled cDNA subtracted with fibroblast RNA. From the subtracted library, 3687 expressed sequence tags (ESTs), representing 2414 unique nucleotide sequences, were isolated, identified by BLAST searches against public databases, and spotted onto a microarray for gene expression profiling. Approximately 30% of these ESTs BLAST to genes of unknown function and 20% have no known homology in the public databases (novel genes). Of the novel genes, 70% are expressed in normal immune tissues by microarray analysis, suggesting that at least 371 of the unidentified EST sequences from the subtracted library are novel porcine genes and can now be further characterized to determine their function in the porcine Peyerʹs patch. We surmise that the products of these genes participate in biochemical and cellular functions related to the unique immunological and gastroenterological functions of the small intestine. The BLAST and gene ontology information for each of the subtracted library EST sequences, the normal and immune stimulated libraries, and the microarray are all valuable resources that will facilitate further examination of the biological function of porcine Peyerʹs patch tissue.