Aberrant mRNA expression of chromatin remodelling factors in round spermatid maturation arrest compared with normal human spermatogenesis

During human spermiogenesis, chromatin condensation is associated with replacement of histones by protamines. This exchange is supported by acetylated histones and chromatin remodelling factors. Ten chromatin remodelling factor protein families are known. This study aims to analyse whether a different chromatin remodelling factor expression pattern exists between normal spermatogenesis and round spermatid maturation arrest as potential reason for impaired spermatogenesis and idiopathic male infertility. Laser capture microdissection was used to excise seminiferous tubules from testicular biopsies with normal spermatogenesis and round spermatid maturation arrest. RNA was isolated, first strand cDNA synthesis and pre-amplification were performed using Epigenetic Chromatin Remodelling Factors PCR arrays with 84 genes. Applying hierarchical cluster analysis, three gene expression clusters with six subgroups were identified. The expression pattern ranges from a few high expressed genes in round spermatid maturation arrest to a multitude of genes (74) which are more highly expressed in normal spermatogenesis than in maturation arrest. A total of 22 genes showed a significant difference between normal spermatogenesis and round spermatid maturation arrest (1 gene was up-regulated and 21 genes were down-regulated in the developmental arrest). The significantly different expression of chromatin remodelling factors between normal spermatogenesis and round spermatid maturation arrest may lead to impaired epigenetic information and aberrant transcription during sperm development representing one possible reason for developmental arrest of round spermatids.