Expression of somatic DNA repair genes in human testes.

Meiosis is the key process for recombination and reduction of the diploid chromosome set to a haploid one. Many genes that have been found in yeast or mouse models to play a role in meiosis are also important for the repair of DNA damage in somatic cells. To study the DNA repair gene transcriptome during male germ cell development, we have developed a specialized cDNA microarray with 181 human genes which are involved in different somatic DNA repair pathways and/or cell cycle control and 45 control house-keeping genes. This DNA repair gene chip was used to quantify the mRNA expression levels in three human testes samples versus a fibroblast RNA pool. Two hundred twenty genes on the chip (including house-keeping genes) showed detectable expression levels in adult testes. Sixty-four DNA repair- and cell cycle-associated genes showed higher expression levels in testicular cells than in mitotically dividing fibroblasts and, therefore, are likely to be implicated in meiosis. The microarray results of 17 genes with increased expression levels were validated with reverse Northern blots or real-time quantitative RT PCR. Systematic analyses of the meiotic DNA repair gene transcriptome may provide new insights into the genetics of male (in)fertility.