GSE70198
The microRNA signature of mouse spermatozoa is dynamically modified during epididymal maturation
In recent years considerable effort has been devoted to understanding the epigenetic control of sperm development leading to an increased appreciation of the importance of RNA interference pathways, and in particular microRNAs (miRNAs), as key regulators of spermatogenesis and epididymal maturation. It has also been shown that sperm are endowed with an impressive array of miRNA that have been implicated in various aspects of fertilization and embryo development. However, to date there have been no reports on whether the sperm miRNA signature is static or whether it is influenced by their prolonged maturation within the male reproductive tract. To investigate this phenomenon we employed next generation sequencing to systematically profile the miRNA signature of maturing mouse spermatozoa. In so doing we have provided the first evidence for the dynamic post-testicular modification of the sperm miRNA profile under normal physiological conditions. Such modifications include the apparent loss and acquisition of an impressive cohort of some 113 and 115 miRNAs, respectively between the proximal and distal epididymal segments. Interestingly, the majority of these changes occur late in maturation and include the uptake of novel miRNA species in addition to a significant increase in many miRNAs natively expressed in immature sperm. Since sperm are not capable of de novo transcription these findings identify the epididymis as an important site in establishing the sperm epigenome with the potential to condition the peri-conceptual environment of the female reproductive tract, contribute to the inheritance of acquired characteristics, and/or alter the developmental trajectory of the resulting offspring. Overall design: Examination of the microRNA expression profile in sperm thoughout the mouse epididymis and mouse using next generation sequencing in duplicate.