KATP channel subunits are expressed in the epididymal epithelium in several mammalian species.
Adenosine triphosphate-sensitive K(++) (K(ATP)) channels are poorly characterized in the reproductive tract. The present study was designed to evaluate the putative expression of K(ATP) channel subunits (Kir6.x and SURx) in the epididymis from different mammalian species. Immunohistochemical, Western blot, and RT-PCR techniques were used. A positive immunostaining for Kir6.2 (KCNJ11) and SUR2 (ABCC9) was observed by immunoenzymatic and immunofluorescent approaches in the principal epithelial cells throughout all regions of the rat and mouse epididymis. Double labeling with anti-aquaporin 9 (AQP9) and anti-Kir6.2 (KCNJ11) confirmed their colocalization in the principal cells. No immunostaining could be demonstrated for Kir6.1 (KCNJ8) and SUR1 (ABCC8) subunits. Under higher magnification, the immunostaining for Kir6.2 (KCNJ11) exhibited a cytoplasmic labeling that was more intense at the level of the Golgi apparatus along the whole epididymis. A similar pattern was observed for SUR2 (ABCC9), although in the latter case, the Golgi labeling appeared to be region specific. Spermatozoa in epididymal tubules from rodents also immunostained for Kir6.2 (KCNJ11) and SUR2 (ABCC9). Western blot analysis of epididymal total protein and crude membrane extracts from adult and prepubertal rats confirmed the presence of Kir6.2 (KCNJ11). SUR2 (ABCC9) protein expression was detected in adult epididymal extracts. Furthermore, RT-PCR established the presence of Kir6.2 (KCNJ11) and SUR2 (ABCC9) mRNA in prepubertal and adult mouse epididymis. Indirect immunofluorescence also documented the presence of Kir6.2 (KCNJ11) and SUR2 (ABCC9) in the epididymal epithelium, as well as in spermatozoa, of canine, feline, bovine, and human origin. These data demonstrate the presence of the K(ATP) channel subunits, Kir6.2 (KCNJ11) and SUR2 (ABCC9), in epididymal epithelial cells and spermatozoa from several mammalian species. Although their physiological roles need to be fully characterized, it is tempting to propose that such types of K(++) channels might be involved in protein secretion and fluid-electrolyte transport occurring along the epididymal epithelium, leading to spermatozoa maturation.
Lybaert
Pascale
P
Laboratory of Experimental Hormonology, Faculty of Medicine, Université Libre de Bruxelles (ULB), B-1070 Brussels, Belgium. plybaert@ulb.ac.be
Vanbellinghen
Anne Marie
AM
Quertinmont
Eric
E
Petein
Michel
M
Meuris
Sylvain
S
Lebrun
Philippe
P
D018528:ATP-Binding Cassette Transporters / Q000235:genetics / Q000378:metabolism; D000818:Animals; D002415:Cats; D002417:Cattle; D004285:Dogs; D004822:Epididymis / Q000378:metabolism*; D004848:Epithelium / Q000378:metabolism*; D006801:Humans; D054086:KATP Channels / Q000235:genetics / Q000378:metabolism*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D024661:Potassium Channels, Inwardly Rectifying / Q000235:genetics / Q000378:metabolism; D021122:Protein Subunits / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D011955:Receptors, Drug / Q000235:genetics / Q000378:metabolism; D013045:Species Specificity; D064233:Sulfonylurea Receptors; D000099161:Kcnj11 Channel
D018528:ATP-Binding Cassette Transporters; D054086:KATP Channels; D024661:Potassium Channels, Inwardly Rectifying; D021122:Protein Subunits; D011955:Receptors, Drug; D064233:Sulfonylurea Receptors; D000099161:Kcnj11 Channel; C577507:ABCC8 protein, human; C577510:ABCC9 protein, human; C577508:Abcc8 protein, mouse; C577509:Abcc8 protein, rat; C577512:Abcc9 protein, rat