Comparative analysis of an unusual gene arrangement in the human chromosome 1

Antisense transcripts are widespread phenomenon in eukaryotes. However, protein coding genes overlapping with other protein genes at both, ends are very rare in the human and other vertebrate genomes. Here, we report a comparative analysis of a region in the human chromosome 1 where two neighboring genes overlap with other genes at each end. The aim of this study was to analyze the evolution of this phenomenon and to identify relations, if any, in the expression patterns of the involved genes. We identified orthologs of six genes from the human region 1p34.3-1p34.1, MUTYH, TOE1, TESK2, LOC126661, MMACHC, and PRDX1, in vertebrates, insects, sea urchin, and Arabidopsis genomes and performed detailed analysis of their genomic arrangements. In addition we investigated expression of these genes in humans and mice. Presented data demonstrate that this specific arrangement of six genes is primate specific and involves both, genes conserved in all lineages as well as young, lineage specific genes. The overlap of these genes does not enforce any specific pattern of gene expression and no pair of overlapping genes showed negative correlation in the expression pattern. Additionally, this study shows that overlapping genes tend to have more splice variants then their non-overlapping orthologs and that there is a big dynamics in the gene structure evolution resulting in colossal differences in gene structure in closely related species.