Prominin‐1 deletion results in spermatogenic impairment, sperm morphological defects, and infertility in mice

Abstract

PurposeSpermatogenesis is a complex process orchestrated by several essential genes. Prominin‐1 (Prom1/PROM1) is a gene that is expressed in the testis but with a poorly understood role in spermatogenesis.MethodsWe used Prom1 knockout (Prom1 KO) mice to assess the role of Prom1 in spermatogenesis. To this end, we performed immunohistochemistry, immunofluorescence, western blotting, β‐galactosidase staining, and apoptosis assay. Additionally, we analyzed the morphology of sperm and assessed litter sizes.ResultsWe observed that PROM1 is localized to the dividing spermatocytes in seminiferous epithelial cells, sperm, and columnar epithelium in the epididymis. In the Prom1 KO testis, an aberrant increase in apoptotic cells and a decrease in proliferating seminiferous epithelial cells were observed. Cellular FLICE‐like inhibitory protein (c‐FLIP) and extracellular signal‐regulated kinase 1/2 (ERK1/2) expression were also significantly decreased in Prom1 KO testis. In addition, a significantly increased number of epididymal spermatozoa with abnormal morphology and less motility was found in Prom1 KO mice.ConclusionsPROM1 maintains spermatogenic cell proliferation and survival via c‐FLIP expression in the testis. It is also involved in sperm motility and fertilization potential. The mechanism underlying the effect of Prom1 on sperm morphology and motility remains to be identified.

Prominin‐1 expression in the testis/epididymis and fertility

“…Prominin‐1 transcripts were later mapped in the luminal zone of the contorted seminiferous tubules containing spermatids and in the epididymal duct by in situ hybridization (Table 1). 4 Matsukuma and colleagues confirmed this last observation by β‐galactosidase staining of heterozygote animals of a knock‐in mouse model carrying the LacZ gene in the Prom1 locus 1 . Strikingly, while neither Prominin‐1 transcript expression 4 nor LacZ staining 1 were detected in the basal portion of seminiferous tubules containing actively dividing spermatogonia, the immunodetection in the latter study contradicted these findings and also failed to detect Prominin‐1 protein in developing spermatozoa 1 .…”

“…4 these findings and also failed to detect Prominin-1 protein in developing spermatozoa. 1 The reason for these discrepancies was not discussed by the authors and remains to be determined. The use of an anti-Prominin-1 antibody (HPA004922; Sigma-Aldrich), which is directed against a sequence of human Prominin-1 sharing only 56% identity with its mouse counterpart, may be part of the answer.…”

“…Of note, Karim and colleagues were the first to observe compromised spermatogenesis in some (without indicating in which proportion) Prom1 −/ − males on a less characterized 129SvEv background, although they reported no interference with development or fertility in general 10 . It appears therefore that the drastic effect on male fertility reported by Matsukuma and colleagues may be influenced by factors other than the sole absence of Prominin‐1 1 . One cannot exclude that a substrain of Prom1 −/ − may have been derived given that the original publication in 2009 of these engineered animals did not report fertility issues and the distributor (Strain Data Sheet, BRC No.…”

“…Actually, most anti‐Prominin‐1 antibodies do not cross‐react between mouse and human counterparts 5 . As this antibody is not reported to react with species other than human, its cross‐reactivity with murine Prominin‐1 needs to be demonstrated first 1 . As for the antibody (18470‐1‐AP, Proteintech) used for the immunoblot of testicular samples, 1 although presented as reactive against mouse Prominin‐1 despite being also raised against human Prominin‐1, it is specifically directed against the C‐terminal region of the 120‐kDa kidney form that is partly absent in the 100‐kDa variant expressed in the testis (Table 1).…”

“…Matsukuma and colleagues have recently reported that Prominin‐1 deletion results in spermatogenic impairment, sperm morphological defects, and infertility in mice 1 . Prominin‐1 (alias CD133) has been, for more than two decades, the subject of intensive research in various organ systems due to its expression in stem (cancer stem) cells.…”