Cloning and Functional Expression of a Second New Aquaporin Abundantly Expressed in Testis

Ishibashi, Keiichiro; Kuwahara, Michio; Kageyama, Yukio; Tohsaka, Akira; Marumo, Fumiaki; Sasaki, Sei

doi:10.1006/bbrc.1997.7219

Cited by 180 publications

(105 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Ag ϩ acts by binding to cysteine or histidine residues in proteins. Both hAQP8 and AtTIP1;1 contain cysteine residues in their pore region that have been identified as targets for inhibition by mercury when water permeability was investigated in oocyte swelling assays (30,31). Ag ϩ is also a biocide with various negative effects on organisms.…”

Section: Expression Of Aquaporins Increase the Sensitivity Of Yeast Cmentioning

confidence: 99%

Specific Aquaporins Facilitate the Diffusion of Hydrogen Peroxide across Membranes

Bienert

Møller

Kristiansen

et al. 2007

Journal of Biological Chemistry

1,120

775

View full text Add to dashboard Cite

The metabolism of aerobic organisms continuously produces reactive oxygen species. Although potentially toxic, these compounds also function in signaling. One important feature of signaling compounds is their ability to move between different compartments, e.g. to cross membranes. Here we present evidence that aquaporins can channel hydrogen peroxide (H 2 O 2 ). Twenty-four aquaporins from plants and mammals were screened in five yeast strains differing in sensitivity toward oxidative stress. Expression of human AQP8 and plant Arabidopsis TIP1;1 and TIP1;2 in yeast decreased growth and survival in the presence of H 2 O 2 . Further evidence for aquaporin-mediated H 2 O 2 diffusion was obtained by a fluorescence assay with intact yeast cells using an intracellular reactive oxygen species-sensitive fluorescent dye. Application of silver ions (Ag ؉ ), which block aquaporin-mediated water diffusion in a fast kinetics swelling assay, also reversed both the aquaporindependent growth repression and the H 2 O 2 -induced fluorescence. Our results present the first molecular genetic evidence for the diffusion of H 2 O 2 through specific members of the aquaporin family.Hydrogen peroxide (H 2 O 2 ) 2 belongs to the group of reactive oxygen species (ROS). ROS are generated in a number of key metabolic processes in cells like the electron transport chain in the inner mitochondrial membrane (1) and, specific for plants, the chloroplast thylakoid membrane (2).Because ROS can potentially damage proteins, lipids, and nucleic acids, cells have a number of ROS-scavenging systems that are able to remove these molecules and to maintain a relatively low and constant ROS concentration (3). However, ROS are also intermediates in various signal transduction pathways and have been shown to initiate responses to various stresses and disorders (for recent reviews, see Refs. 4 and 5). Arabidopsis mutants lacking an NADPH oxidase were not able to respond adequately to potassium deficiency (6) and were impaired in stomatal closure (7), providing genetic evidence for a role of NADPH oxidase in signaling.ROS are interconvertible molecules including singlet oxygen, superoxide, hydroxyl radical, and H 2 O 2 . H 2 O 2 has a distinctive set of features compared with other ROS. (i) It is not charged, (ii) it is not a radical, (iii) it possesses an intermediate oxidation number, (iv) it is relatively stable under physiological conditions, and (v) catalase can disproportionate it into water and molecular oxygen without the expense of reduction equivalents.Although substantial progress has been made regarding the formation and scavenging of ROS, little is known about their transport from the site of origin to the place of action or detoxification. Recently three studies from mammalian systems have provided evidence that H 2 O 2 , in addition to the well studied role in intracellular signaling, is also used as an intercellular signal molecule (8 -10). This implies that a necessary step within these signal transduction pathways is the transport of H 2 O 2 ...

show abstract

Section: Expression Of Aquaporins Increase the Sensitivity Of Yeast Cmentioning

confidence: 99%

Specific Aquaporins Facilitate the Diffusion of Hydrogen Peroxide across Membranes

Bienert

Møller

Kristiansen

et al. 2007

Journal of Biological Chemistry

1,120

775

View full text Add to dashboard Cite

show abstract

“…Similar to AQP7, AQP8 was first identified through its cloning from testicular cDNA [60]. In contrast to AQP7, however, cellular localization of this AQP in the testis is most controversial.…”

Section: Aqp8mentioning

confidence: 99%

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

Yeung¹

2010

Asian J Androl

View full text Add to dashboard Cite

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.

show abstract

“…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%

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

Yeung

Cooper²

2010

Reproduction

View full text Add to dashboard Cite

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.

show abstract

Cloning and Functional Expression of a Second New Aquaporin Abundantly Expressed in Testis

Cited by 180 publications

References 12 publications

Specific Aquaporins Facilitate the Diffusion of Hydrogen Peroxide across Membranes

Specific Aquaporins Facilitate the Diffusion of Hydrogen Peroxide across Membranes

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

Contact Info

Product

Resources

About