The epididymis is divided into caput, corpus and cauda regions, organized into intraregional segments separated by connective tissue septa (CTS). In the adult rat and mouse these segments are highly differentiated. Regulation of these segments is by endocrine, lumicrine and paracrine factors, the relative importance of which remains under investigation. Here, the ability of the CTS to limit signaling in the interstitial compartment is reviewed as is the effect of 15 days of unilateral efferent duct ligation (EDL) on ipsilateral segmental transcriptional profiles. Inter-segmental microperifusions of epidermal growth factor (EGF), vascular endothelial growth factor (VEGFA) and fibroblast growth factor 2 (FGF2) increased phosphorylation of mitogen activated protein kinase (MAPK) in segments 1 and 2 of the rat epididymis and the effects of all factors were limited by the CTS separating the segments. Microarray analysis of segmental gene expression determined the effect of 15 days of unilateral EDL on the transcriptome-wide gene expression of rat segments 1-4. Over 11,000 genes were expressed in each of the four segments and over 2000 transcripts in segment 1 responded to deprivation of testicular lumicrine factors. Segments 1 and 2 of control tissues were the most transcriptionally different and EDL had its greatest effects there. In the absence of lumicrine factors, all four segments regressed to a transcriptionally undifferentiated state, consistent with the less differentiated histology. Deprivation of lumicrine factors could stimulate an individual gene's expression in some segments yet suppress it in others. Such results reveal a higher complexity of the regulation of rat epididymal segments than that is generally appreciated.
Animals ; Ejaculatory Ducts ; physiology ; Epididymis ; drug effects ; physiology ; Gene Expression Regulation ; drug effects ; Growth Substances ; pharmacology ; Male ; Mice ; Rats ; Reverse Transcriptase Polymerase Chain Reaction ; Signal Transduction

As part of our efforts to identify novel contraceptive targets in the epididymis we performed transcriptional profiling on each of the 10 and 19 segments of the mouse and rat epididymidis, respectively, using Affymetrix whole genome microarrays. A total of 17 096 and 16 360 probe sets representing transcripts were identified as being expressed in the segmented mouse and rat epididymal transcriptomes, respectively. Comparison of the expressed murine transcripts against a mouse transcriptional profiling database derived from 22 other mouse tissues identified 77 transcripts that were expressed uniquely in the epididymis. The expression of these genes was further evaluated by reverse transcription polymerase chain reaction (RT-PCR) analysis of RNA from 21 mouse tissues. RT-PCR analysis confirmed epididymis-specific expression of Defensin Beta 13 and identified two additional genes with expression restricted only to the epididymis and testis. Comparison of the 16 360 expressed transcripts in the rat epididymis with data of 21 other tissues from a rat transcriptional profiling database identified 110 transcripts specific for the epididymis. Sixty-two of these transcripts were further investigated by qPCR analysis. Only Defensin 22 (E3 epididymal protein) was shown to be completely specific for the epididymis. In addition, 14 transcripts showed more than 100-fold selective expression in the epididymis. The products of these genes might play important roles in epididymal and/or sperm function and further investigation and validation as contraceptive targets are warranted. The results of the studies described in this report are available at the Mammalian Reproductive Genetics (MRG) Database (http://mrg.genetics.washington.edu/).
Animals ; Epididymis ; physiology ; Gene Expression Profiling ; methods ; Male ; Mice ; Organ Specificity ; RNA ; genetics ; isolation & purification ; Rats ; Reverse Transcriptase Polymerase Chain Reaction ; Transcription, Genetic

Cysteine-rich secretory protein-1 (CRISP-1) is a glycoprotein secreted by the epididymal epithelium. It is a member of a large family of proteins characterized by two conserved domains and a set of 16 conserved cysteine residues. In mammals, CRISP-1 inhibits sperm-egg fusion and can suppress sperm capacitation. The molecular mechanism of action of the mammalian CRISP proteins remains unknown, but certain non-mammalian CRISP proteins can block ion channels. In the rat, CRISP-1 comprises two forms referred to as Proteins D and E. Recent work in our laboratory demonstrates that the D form of CRISP-1 associates transiently with the sperm surface, whereas the E form binds tightly. When the spermatozoa are washed, the E form of CRISP-1 persists on the sperm surface after all D form has dissociated. Cross-linking studies demonstrate different protein-protein interaction patterns for D and E, although no binding partners for either protein have yet been identified. Mass spectrometric analyses revealed a potential post-translational modification on the E form that is not present on the D form. This is the only discernable difference between Proteins D and E, and presumably is responsible for the difference in behavior of these two forms of rat CRISP-1. These studies demonstrate that the more abundant D form interacts with spermatozoa transiently, possibly with a specific receptor on the sperm surface, consistent with a capacitation-suppressing function during sperm transit and storage in the epididymis, and also confirm a tightly bound population of the E form that could act in the female reproductive tract.
Amino Acid Sequence ; Animals ; Conserved Sequence ; Humans ; Male ; Mammals ; Membrane Glycoproteins ; genetics ; metabolism ; Molecular Sequence Data ; Rats ; Spermatozoa ; physiology