Differential gene expression profiles of human efferent ducts and proximal epididymis.

BACKGROUND

Gene expression patterns along the epididymis are established by specific transcription factor networks that coordinate region-specific functions. In rodents, the epididymis can be divided in up to 19 segments. Based on gross anatomy, the human epididymis is divided into caput, corpus, and cauda segments together with efferent ducts that occupy the proximal part of this organ.

OBJECTIVES

To determine to which extent gene expression pattern is segmented along the efferent ducts and the proximal region of the epididymis in men of reproductive age.

MATERIALS AND

METHODS

Epididymal transcriptome profiling was performed on eight distinct regions from three donors. Microarray analysis was performed on a gene-chip microarray. Differentially expressed genes (DEGs)>2-fold change (P < .05) were clustered in relation to their intensity profiles. Overrepresented biological functions from gene ontology were searched using DAVID 6.8. Expression profiles were validated by qRT-PCR quantification of selected genes.

RESULTS

There were no DEGs among segments 1-3 of efferent ducts region neither among segments 4-6 of the caput epididymis. 1058 DEGs were identified between efferent ducts and the epididymis, whereas 444 and 846 DEGs distinguished the caput from the corpus (section 7) and cauda (section 8) epididymis, respectively. A total of 131 DEGs were detected between corpus (7) and cauda (8) transcriptomes. Up-regulated DEGs in the efferent ducts were predominantly related to cilium assembly/movement and cell differentiation. Fertilization, defense, and immune responses were associated with caput epididymis (4-6), while spermatogenesis and protein binding were found all along the epididymis (4-8).

DISCUSSION: The proximal human epididymis is exclusively occupied by efferent ducts with a distinct DEG profile compared with the downstream epididymal segments. Moreover, gene expression profiling revealed two regions in the human epididymis: the caput and the distal corpus/cauda region.

CONCLUSIONS

Human epididymal transcriptome reveals limited DEGs, and efferent ducts have a distinct DEGs profile.