Channels for water efflux and influx involved in volume regulation of murine spermatozoa

Callies, Chiara; Cooper, Trevor G.; Yeung, Ching‐Hei

doi:10.1530/rep-08-0149

Cited by 8 publications

(5 citation statements)

References 67 publications

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“…Despite early reports of the absence of AQP1 from ovine and human spermatozoa by western blotting [44,55], a positive finding was claimed in canine spermatozoa, although there was no report on the localization of the protein [56]. In addition to localization in vascular endothelial cells, the presence of AQP1 on the germ cell membrane and in the cytoplasm of elongated spermatids was observed in the testis of high-grade varicocele patients, but not on their ejaculated spermatozoa [57].…”

Section: Aqp0-6mentioning

confidence: 88%

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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: Aqp0-6mentioning

confidence: 88%

“…Therefore the identities of AQPs in a cell type have to be validated at multiple levels including the encoding mRNA, the specific protein, as well as its cellular localization. To date, AQP7, 8 and 11 are the three AQPs identified in regulation is blocked [44].…”

Section: Evidence For the Identities Of Sperm Aqpsmentioning

confidence: 99%

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

Yeung¹

2010

Asian J Androl

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“…Aquaporin 8 (AQP8) is also relevant in osmoregulation, as its levels in human sperm have been found to be inversely correlated with the presence of sperm with coiled tails, which is indicative of osmotic stress [ 45 ]. The importance of AQP8 in osmoregulation has also been explored through its inhibition through HgCl 2 , which blocks quinine-induced swelling in both human [ 45 ] and mouse sperm [ 47 , 74 ]. In addition, Yeung et al described the importance of AQP8 in water outflow associated with RVD, as its inhibition in mouse sperm through HgCl 2 reduces cell shrinkage in response to osmolyte currents [ 47 ].…”

Section: Aquaporins In Mammalian Spermmentioning

confidence: 99%

Relevance of Aquaporins for Gamete Function and Cryopreservation

Delgado-Bermúdez

Ribas-Maynou

Yeste

2022

Animals

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The interaction between cells and the extracellular medium is of great importance, and drastic changes in extracellular solute concentrations drive water movement across the plasma membrane. Aquaporins (AQPs) are a family of transmembrane channels that allow the transport of water and small solutes across cell membranes. Different members of this family have been identified in gametes. In sperm, they are relevant to osmoadaptation after entering the female reproductive tract, which is crucial for sperm motility activation and capacitation and, thus, for their fertilizing ability. In addition, they are relevant during the cryopreservation process, since some members of this family are also permeable to glycerol, one of the most frequently used cryoprotective agents in livestock. Regarding oocytes, AQPs are very important in their maturation but also during cryopreservation. Further research to define the exact sets of AQPs that are present in oocytes from different species is needed, since the available literature envisages certain AQPs and their roles but does not provide complete information on the whole set of AQPs. This is of considerable importance because, in sperm, specific AQPs are known to compensate the role of non-functional members.

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“…To counteract this negative impact, mammalian sperm have acquired mechanisms to drive rapid transmembrane water movement for efficient cell volume regulation [10]. Indeed, high water permeability has long been found in mammalian sperm [11][12][13], and ion channel-controlled water influx/efflux has been shown to be involved in postcopulatory sperm volume regulation [14][15][16]. However, the sperm protein(s) (such as plasma membrane channels) responsible for this trait have not been identified.…”

Section: Introductionmentioning

confidence: 99%

Aquaporin3 is a sperm water channel essential for postcopulatory sperm osmoadaptation and migration

et al. 2010

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In the journey from the male to female reproductive tract, mammalian sperm experience a natural osmotic decrease (e.g., in mouse, from ~415 mOsm in the cauda epididymis to ~310 mOsm in the uterine cavity). Sperm have evolved to utilize this hypotonic exposure for motility activation, meanwhile efficiently silence the negative impact of hypotonic cell swelling. Previous physiological and pharmacological studies have shown that ion channel-controlled water influx/efflux is actively involved in the process of sperm volume regulation; however, no specific sperm proteins have been found responsible for this rapid osmoadaptation. Here, we report that aquaporin3 (AQP3) is a sperm water channel in mice and humans. Aqp3-deficient sperm show normal motility activation in response to hypotonicity but display increased vulnerability to hypotonic cell swelling, characterized by increased tail bending after entering uterus. The sperm defect is a result of impaired sperm volume regulation and progressive cell swelling in response to physiological hypotonic stress during male-female reproductive tract transition. Time-lapse imaging revealed that the cell volume expansion begins at cytoplasmic droplet, forcing the tail to angulate and form a hairpin-like structure due to mechanical membrane stretch. The tail deformation hampered sperm migration into oviduct, resulting in impaired fertilization and reduced male fertility. These data suggest AQP3 as an essential membrane pathway for sperm regulatory volume decrease (RVD) that balances the "trade-off" between sperm motility and cell swelling upon physiological hypotonicity, thereby optimizing postcopulatory sperm behavior.

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Channels for water efflux and influx involved in volume regulation of murine spermatozoa

Cited by 8 publications

References 67 publications

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

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

Relevance of Aquaporins for Gamete Function and Cryopreservation

Aquaporin3 is a sperm water channel essential for postcopulatory sperm osmoadaptation and migration

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