Localization of Aquaporin-7 in Human Testis and Ejaculated Sperm: Possible Involvement in Maintenance of Sperm Quality

Saito, Kazutaka; Kageyama, Yukio; Okada, Yohei; Kawakami, Satoru; Kihara, Kazunori; Ishibashi, Keiichiro; Sasaki, Sei

doi:10.1097/01.ju.0000141499.08650.ab

Cited by 74 publications

(68 citation statements)

References 18 publications

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“…The presence of glycerol in the rat epididymis and its metabolism by spermatozoa has been reported [75]. In a study of 22 infertile men, sperm AQP7 was nondetectable in five of them who showed slightly lower sperm motility than the other patients [76]. In a cohort of 50 men, AQP7 expression in ejaculated sperm was correlated with their progressive motility, with low values for both parameters in infertile patients compared with donors [58].…”

Section: Aqp7mentioning

confidence: 97%

Aquaporins in spermatozoa and testicular germ cells: identification and potential role

Yeung¹

2010

Asian J Androl

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Mammalian spermatozoa have relatively high water permeability and swell readily, as in the hypo-osmotic swelling test used in the andrology clinic. Physiologically, spermatozoa experience changes in the osmolality of the surrounding fluids in both the male and the female tracts on their journey from the testis to the ovum. Sperm volume regulation in response to such osmotic challenges is important to maintain a stable cell size for the normal shape and function of the sperm tail. Alongside ion channels for the fluxes of osmolytes, water channels would be crucial for sperm volume regulation. In contrast to the deep knowledge and numerous studies on somatic cell aquaporins (AQPs), the understanding of sperm AQPs is limited. Among the 13 AQPs, convincing evidence for their presence in spermatozoa has been confined to AQP7, AQP8 and AQP11. Overall, current findings indicate a major role of AQP8 in water influx and efflux for sperm volume regulation, which is required for natural fertilization. The preliminary data suggestive of a role for AQP7 in sperm glycerol metabolism needs further substantiation. The association of AQP11 with the residual cytoplasm of elongated spermatids and the distal tail of spermatozoa supports the hypothesis of more than just a role in conferring water permeability and also in the turnover and recycling of surplus cellular components made redundant during spermiogenesis and spermiation. This would be crucial for the maintenance of a germinal epithelium functioning efficiently in the production of spermatozoa.

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Section: Aqp7mentioning

confidence: 97%

Aquaporins in spermatozoa and testicular germ cells: identification and potential role

Yeung¹

2010

Asian J Androl

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“…It is well established that the testis expresses AQP7 and AQP8 both at the mRNA and protein levels. AQP7, which was first cloned from the testis (Ishibashi et al 1997), is expressed initially in the round spermatids (Kageyama et al 2001) and is also localised to the sperm tail in the rat (Ishibashi et al 1997, Suzuki-Toyota et al 1999, Kageyama et al 2001, mouse (Skowronski et al 2007) and human (Saito et al 2004). The role of AQP7 in male reproductive physiology is unclear as knockout mice are fertile, producing normal functional spermatozoa , whereas an association with sperm motility has been suggested in infertile men (Saito et al 2004).…”

Section: Introductionmentioning

confidence: 99%

“…AQP7, which was first cloned from the testis (Ishibashi et al 1997), is expressed initially in the round spermatids (Kageyama et al 2001) and is also localised to the sperm tail in the rat (Ishibashi et al 1997, Suzuki-Toyota et al 1999, Kageyama et al 2001, mouse (Skowronski et al 2007) and human (Saito et al 2004). The role of AQP7 in male reproductive physiology is unclear as knockout mice are fertile, producing normal functional spermatozoa , whereas an association with sperm motility has been suggested in infertile men (Saito et al 2004). Although there are many studies on AQP8 in the testis, reports on the cellular localisation are inconsistent, ranging from spermatogenic cells in general (Elkjaer et al 2001, Kageyama et al 2001, Yang et al 2005, in elongated spermatids (ES), residual bodies and primary spermatocytes (Calamita et al 2001) and exclusively in Sertoli cells (Badran & Hermo 2002).…”

Section: Introductionmentioning

confidence: 99%

Aquaporin AQP11 in the testis: molecular identity and association with the processing of residual cytoplasm of elongated spermatids

Yeung

Cooper²

2010

Reproduction

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AQP11 is one of the latest aquaporin (AQP) family members found, which differs from the other AQPs by its intracellular localisation and unusual water pore nucleotides with unclear function. Despite the highest mRNA expression among organs having been reported in the testis, the testicular molecule has not been studied in detail. Immunohistochemistry of rat adult testis localised AQP11 to the elongated spermatids (ES) and no other cell types except residual bodies inside Sertoli cells. It was absent from early ES at least until stage 13, and after a first diffuse appearance in the caudal cytoplasm became concentrated in intracellular organelles by stage 17, was strongest in vesicles in the anterior cytoplasm at the final ES stages and appeared in residual bodies. Staining was detected on the distal quarter of the sperm tail only immediately before spermiation. A similar localisation was found in the mouse and developmental profiles for both the open reading frame mRNA and protein expression in 8-50 dpp testis pinpointed its first appearance coinciding with late stage ES. Sequencing of PCR products of testicular Aqp11 containing the open reading frames confirmed a full match with GenBank databases for rat, mouse and human. Western blotting revealed two or more molecular forms with the 26/27 kDa species dominating in the rat/mouse testis and the 33/34 kDa form selectively allocated to the spermatozoa. In view of intracellular vacuolation leading to polycystic kidney in Aqp11-null mice, a possible role of testicular AQP11 in the recycling of surplus cytoplasmic components of the ES and sustaining Sertoli cell capacity in the support of spermatogenesis was discussed.

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“…In addition, Hermo and Smith [2011] observed an AQP7 immunoreaction over the whole cytoplasm of late elongating spermatids located near the lumen of rat seminiferous epithelium. AQP7 is expressed in human spermatids and sperm at the tail level [Saito et al 2004;. In human ejaculated sperm, Saito et al [2004] reported immunolabeling in the midpiece region and the anterior portion of the tail, whereas showed the presence of AQP7 along the entire flagellum, with an intensity that varied from cell to cell.…”

Section: Introductionmentioning

confidence: 99%

“…AQP7 is expressed in human spermatids and sperm at the tail level [Saito et al 2004;. In human ejaculated sperm, Saito et al [2004] reported immunolabeling in the midpiece region and the anterior portion of the tail, whereas showed the presence of AQP7 along the entire flagellum, with an intensity that varied from cell to cell. Although this protein seems to play a role in late spermatogenesis and to be involved in mechanisms of male fertility, the function of AQP7 in the male reproductive Figure 1.…”

Section: Introductionmentioning

confidence: 99%

Immunolocalization of aquaporin 7 in human sperm and its relationship with semen parameters

Moretti

Terzuoli²,

Mazzi³

et al. 2011

Systems Biology in Reproductive Medicine

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Aquaporins (AQPs) are a family of 13 small hydrophobic transmembrane proteins expressed in numerous tissues and cells. Some AQPs work as strict water channels, others are permeable to a range of substances, including glycerol. In the male reproductive system their localization in testis, efferent ducts, epididymis, and spermatozoa has been described. We studied the distribution of AQP7 in ejaculated human sperm and the relationship between AQP7 labeling and sperm characteristics. Semen samples from 33 men were examined by light and transmission electron microscopy (TEM). TEM data were quantified using a mathematical formula that calculates a fertility index (FI) and the percentages of sperm apoptosis, immaturity, and necrosis. Immunocytochemistry with a polyclonal antibody anti-AQP7 was performed on the sperm samples. Normal sperm were labeled in the pericentriolar area, midpiece, equatorial segment, and weakly in the tail (grade 1). Abnormal sperm showed a diffuse low intensity of fluorescence evident in the cytoplasmic residues, coiled tails, in the entire head, and acrosome (grade 2). A high number of motile sperm obtained by swim up were labeled in a dotted manner in the mitochondria. A significant positive correlation was found between the spermatozoa with AQP7 grade 1 labeling and the percentage of normal form (P < 0.008), progressive motility and FI (P < 0.005); a negative correlation was noted with the percentages of cytoplasmic residues (P < 0.010) and immaturity (P < 0.006) and coiled tails (P < 0.012). The link between AQP7 distribution and sperm morphology and the particular dotted labeling in swim up selected motile sperm are novel and deserve additional studies.

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Localization of Aquaporin-7 in Human Testis and Ejaculated Sperm: Possible Involvement in Maintenance of Sperm Quality

Abstract: AQP7 shows a spatial expression pattern in the human testis. AQP7 may be involved in the maintenance of sperm motility. Furthermore, a lack of AQP7 expression in sperm may be an underlying mechanism of male infertility.

Cited by 74 publications

References 18 publications

Aquaporins in spermatozoa and testicular germ cells: identification and potential role

Aquaporins in spermatozoa and testicular germ cells: identification and potential role

Aquaporin AQP11 in the testis: molecular identity and association with the processing of residual cytoplasm of elongated spermatids

Immunolocalization of aquaporin 7 in human sperm and its relationship with semen parameters

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