Detection of the activator cAMP responsive element modulator (CREM) isoform ortholog proteins in porcine spermatids and sperm

It is necessary to obtain basic information on transcription factors expressed in the spermatids of livestock to determine mechanisms of defective spermiogenesis. In this study, we characterized the activator cAMP responsive element modulator (CREM) ortholog isoforms in porcine testicular germ cells and ejaculated sperm. At least two kinds of porcine activator CREM τ family ortholog mRNAs were more strongly expressed in the testis than in kidney or liver. The activator CREM isoform ortholog proteins were localized in nuclei of round spermatids and around nuclei of elongated spermatids. Furthermore, approximately 34% of ejaculated sperm had the activator CREM isoform ortholog proteins at their connecting piece. This is apparently the first report demonstrating the expression and localization of the activator CREM isoform ortholog proteins in spermatids and ejaculated sperm of a livestock species.