Aquaporin channels (AQPs) are known to play an important role in the development of ovarian follicles through their function in water transport pathways. Compared to other AQPs, research on the role of AQP4 in female reproductive physiology, particularly in cattle, remains limited. In our previous study, gene chip microarray data showed a downregulation of AQP4 in bovine cystic follicles. This study was performed to validate the AQP4 expression level at the protein level in bovine follicles using immunohistochemistry, Western blotting, and immunoprecipitation assays. Immunostaining data showed that AQP4 was expressed in granulosa and theca cells of bovine ovarian follicles. The ovarian follicles were classified according to size as small (< 10 mm) or large (> 25 mm) in diameter. Consistent with earlier microarray data, semi-quantitative PCR data showed a decrease in AQP4 mRNA expression in large follicles. Western blot analysis showed a downregulation of the AQP4 protein in large follicles. In addition, AQP4 was immunoprecipitated and blotted with anti-AQP4 antibody in small and large follicles. Accordingly, AQP4 exhibited a low expression in large follicles. These results show that AQP4 is downregulated in bovine ovarian large follicles, suggesting that the downregulation of AQP4 expression may interfere with follicular water transport, leading to bovine follicular cysts.

Molecular mimicry is the most common mechanism that breaches self-tolerance. We previously identified autoantibodies to aquaporin-5 (AQP5) in the sera of patients with Sjögren’s syndrome and found that the aquaporin of Prevotella melaninogenica (PmAqp), an oral commensal, is highly homologous to human AQP5. This study aimed to test whether PmAqp can induce anti-AQP5 autoantibodies via molecular mimicry. From the amino acid sequence of PmAqp, an immunizing peptide; i.e., PmE-L, was designed, which contained both the B cell epitope “E” and T cell epitope. C57BL/6 and BALB/c mice were subcutaneously immunized with linear or cyclic forms of PmE-L emulsified in incomplete Freund’s adjuvant. The concentrations of the antibodies in sera were measured using enzymelinked immunosorbent assays. Both linear and cyclic PmE-L induced high levels of antibodies against not only the immunized peptides but also autoantibodies against AQP5E and antibodies against PmE, a Pm homolog of AQP5E. In C57BL/6 mice; however, the cyclic form of PmE-L was more efficient than the linear form in inducing autoantibodies against AQP5E that contained a cyclic epitope. The levels of anti-PmE antibodies and anti-AQP5E autoantibodies showed a strong positive correlation (r = 0.95, p < 0.0005), suggesting molecular mimicry. Collectively, the mice produced anti-AQP5E autoantibodies in response to a PmAqp-derived peptide. This model proved to be useful for studying the mechanisms of autoantibody production by molecular mimicry.

Alcohol intake is known to affect various organs in the human body, causing reduction of salivation in the oral cavity. Hypo-salivation effect of alcohol is a common feature, but the mechanism in salivary glands is still poorly studied. Therefore, in this study, the changes in salivary secretion and water channel protein (aquaporin5, AQP5) in salivary glands of mice were investigated after ethanol administration. Animals were divided in to 4 groups with the control, 4 g/kg ethanol, 8 g/kg ethanol and 16 g/kg ethanol administration groups. One hour after ethanol administration, saliva was collected from the oral cavity, and the animals were killed and parotid and submandibular glands were extracted to analyze the histopathology, AQP5 immunihistochemistry and AQP5 protein level. According to the results, the salivation rate decreased irrespective of the ethanol dose in mice, and viscosities increased with increase in ethanol dose. However, there were no pathological changes in parotid and submandibular glands due to ethanol administration. Expression of AQP5 in parotid and submandibular glands decreased with increase ethanol administration These results indicate that the reduction of salivary secretion due to acute alcohol intake is closely related to decrease of the water channel protein such as AQP5 in parotid glands and submandibular glands, rather than the damage of salivary glands.

Aquaporin Z and bacteriorhodopsin known as membrane protein transport water molecules and protons, respectively, in and out of the cell in highly selective manner. The selective character of these biomolecules can be applied to water filtration or other industry. However, transmembrane protein like as aquaporin Z and bacteriorhodopsin has many problems for using associated with expression, purification, and activation of protein character. To solve these problems, we developed purification system and characterization method for transmembrane protein. Green Fluorescence Protein (GFP)-fused aquaporin Z were expressed in inducible expression vector system, and purified by Ni-NTA affinity chromatography. GFP-fused aquaporin Z proteins were incorporated into the liposome for optical observation of water flux, and tested in hypertonic external condition by osmotic pressure to check water molecule selective transport. Bacteriorhodopsin was acquired by same method for aquaporin Z purification, but need to activation process by retinal cofactor because Escherichia coli has not retinal synthesis system. According to the absorbance spectra analysis, we confirmed that the purified bacteriorhodopsin was activated by retinal. This study will help to understanding of aquaporin Z and bacteriorhodopsin character and industrial application of transmembrane protein.

Alteration in ion channel or transporter expression levels affects cell volume which is produced by movement of water and ion across the plasma membrane. In particular, aquaporin (AQP) channels among ion channels play a crucial role in movement of water across the cell membrane. This study was performed to identify whether AQP expression is changed in bovine follicular cystic follicles using microarray, RT-PCR and Western blotting analyses. In microarray data, AQP4 expression was decreased, whereas AQP7 was increased in cystic follicles. Additional experiments were focused on the AQP7 expression increased in cystic follicles. The microarray data was confirmed by semi-quantitative polymerase chain reaction (PCR) and Western blot analysis. AQP7 mRNA and protein expressions were significantly increased in the cystic follicles (p<0.05). Application of estrogen (10 μg/ml) to bovine ovarian cells showed a trend of increase in AQP7 expression. From these results, we suggest that the increase in AQP7 expression in cystic follicles may play an important role in movement of water in bovine ovary. In addition, AQP7, a aquaglyceroporin permeating water and glycerol, could be a good target in development of methods for the cryopreservation of bovine ovary.

The epididymis in the male reproductive tract is the site where spermatozoa produced from the testis become mature. The epididymis is divided into 4 different segments, initial segment and caput, corpus, and caudal epididymis, depending upon functional and morphological features. Aquaporins (Aqps) are water channel molecules, which are present in the epididymis and play a major role in removal of epididymal water, resulting in creation of microenvironment for sperm maturation and concentration of sperms. Nandrolone decanoate (ND) is a synthetic anabolic-androgenic steroid, which is used to treat clinical diseases and improve physical ability and appearance. Even though it is well determined that the ND causes the male infertility by affecting the testis, little is known the effect of the ND on the epididymis. The present study was focused to examine the effect of ND at different treatment doses and periods on expression of Aqp1 and Aqp9 genes in the epididymis of pubertal rats. Results showed that mRNA expression of Aqp1 and Aqp9 genes among the parts of the epididymis was differentially regulated by ND treatment doses. In addition, treatment periods of ND caused differential expression of Aqp1 and Aqp9 mRNAs among segments of the epididymis. Therefore, it is believed that male infertility induced by ND could be resulted not only from malfunction of the testis but also from aberrant gene expression of Aqp1 and Aqp9 in the epididymis.

Aquaporin (AQP) 3, a facilitated transporter of water and glycerol, expresses in placenta and fetal membranes, but the detailed localization and function of AQP3 in placenta remain unclear. To elucidate a role of AQP3 in placenta, we defined the expression and cellular localization of AQP3 in placenta and fetal membranes, and investigated the structural and functional differences between wild-type and AQP3 null mice. Gestational sacs were removed during mid-gestational period and amniotic fluid was aspirated for measurements of volume and composition. Fetuses with attached placenta and fetal membranes were weighed and processed for histological assessment. AQP3 strongly expressed in basolateral membrane of visceral yolk sac cells of fetal membrane, the syncytiotrophoblasts of the labyrinthine placenta and fetal nucleated red blood cell membrane. Mice lacking AQP3 did not exhibit a significant defect in differentiation of trophoblast stem cells and normal placentation. However, AQP3 null fetuses were smaller than their control litter mates in spite of a decrease in litter size. The total amniotic fluid volume per gestational sac was reduced, but the amniotic fluid-to-fetal weight ratio was increased in AQP3 null mice compared with wild-type mice. Glycerol, free fatty acid and triglyceride levels in amniotic fluid of AQP3 null mice were significantly reduced, whereas lactate level increased when compared to those of wild-type mice. These results suggest a role for AQP3 in supplying nutrients from yolk sac and maternal blood to developing fetus by facilitating transport of glycerol in addition to water, and its implication for the fetal growth in utero.

Efficient infiltration of water through cell membranes is arbitrated by a family of transmembrane water channels called aquaporins (AQPs). Aquaporin belongs to a highly conserved group of membrane proteins called major intrinsic proteins that facilitate the transport of water and a variety of low molecular weight solutes across biological membranes,which is essential for plants to survive in stress conditions. This study identified 59 BrAQP genes from B. rapa database and Br135K microarray dataset, which was formed by applying low-temperature stresses to contrasting Chinese cabbage two inbreed lines, Chiifu and Kenshin. Based on phylogenetic analyses of BrAQPs revealed four distinct subfamilies, such as plasma membrane intrinsic proteins (PIP), tonoplast intrinsic proteins (TIP), NOD26-like intrinsic proteins (NIP), small basic intrinsic proteins (SIP) with aquaporin of Tomato and Arabidopsis thaliana. All BrAQP genes were firstly examined through homology study with existing biotic and abiotic stress resistance-related aquaporin genes of other plant species and found a high degree of homology. We selected PIP subfamily genes for expression analysis based on microarray data with high and differential transcript abundance levels and homology study with stress related aquaporin genes of other plant species. In our study, we characterized all B. rapa aquaporin genes and understanding the BrPIP subfamily gene function in plants under various environmental stimuli, the expressions of BrPIP genes under various abiotic stress conditions including cold, drought, salinity, water logging, ABA treatment and Fusarium oxysporum f. sp. Conglutinans infection were investigated by a quantitative real-time reverse transcription-PCR analysis. In our expression analysis, 4 BrPIP genes showed responsive expression against F. oxysporum f. sp. Conglutinans infection. The selected genes showed an organ-specific expression, and 12 out of 22 BrPIP genes were differentially expressed in Chiifu compared to Kenshin under cold stresses. Only 7 genes showed up regulation under drought stress and incase of salt stress 17 BrPIP genes were more responsiveness. Additionally, 18 BrPIP genes were up regulated by ABA treatment and all BrPIP genes showed down regulation under water logging stress. Together with expression and bioinformatic analyses, our results provides novel basis to allocate the stress-related biological function to each PIP gene.

Environmental conditions during early mammalian embryo development are critical and some adaptational phenomena are observed. However, the mechanisms underlying them remain largely masked. Previously, we reported that AQP5 expression is modified by the environmental condition without losing the developmental potency. In this study, AQP11 was examined instead. To compare expression pattern between in vivo and in vitro, we conducted quantitative RT-PCR and analyzed localization of the AQP11 by whole mount immunofluorescence. When the fertilized embryos were developed in the maternal tracts, the level of Aqp11 transcripts was decreased dramatically until 2-cell stage. Its level increased after 2-cell stage and peaked at 4-cell stage, but decreased again dramatically until morula stage. Its transcript level increased again at blastocyst stage. In contrast, the levels of Aqp11 transcript in embryos cultured in vitro were as follows. The patterns of expression were similar but the overall levels were low compared with those of embryos grown in the maternal tracts. AQP11 proteins were localized in submembrane cytoplasm of embryos collected from maternal reproductive tracts. The immune-reactive signals were detected in both trophectoderm and inner cell mass. However, its localization was altered in in vitro culture condition. It was localized mainly in the plasma membrane of the blastocysts contacting with external environment. The present study suggests that early stage embryo can develop successfully by themselves adapting to their environmental condition through modulation of the expression level and localization of specific genes like AQP11.

Adaptive development of early stage embryo is well established and recently it is explored that the mammalian embryos also have adaptive ability to the stressful environment. However, the mechanisms are largely unknown. In this study, to evaluate the possible role of aquaporin in early embryo developmental adaptation, the expression of aquaporin (AQP) 5 gene which is detected during early development were examined by the environmental condition. To compare expression patterns between in vivo and in vitro, we conducted quantitative RT-PCR and analyzed localization of the AQP5 by whole mount immunofluorescence. At in vivo condition, Aqp5 expressed in oocyte and in all the stages of preimplantation embryo. It showed peak at 2-cell stage and decreased continuously until morula stage. At in vitro condition, Aqp5 expression pattern was similar with in vivo embryos. It expressed both at embryonic genome activation phase and second mid-preimplantation gene activation phase, but the fold changes were modified between in vivo embryos and in vitro embryos. During in vivo development, AQP5 was mainly localized in apical membrane of blastomeres of 4-cell and 8-cell stage embryos, and then it was localized in cytoplasm. However, the main localization area of AQP5 was dramatically shifted after 8-cell stage from cytoplasm to nucleus by in vitro development. Those results explore the modification of Aqp5 expression levels and location of its final products by in vitro culture. It suggests that expression of Aqp5 and the roles of AQP5 in homeostasis can be modulated by in vitro culture, and that early stage embryos can develop successfully by themselves adapting to their condition through modulation of the specific gene expression and localization.

Water channel proteins, aquaporins (AQPs) contribute to transepithelial water movement in many tissues. To date, 13 mammalian AQPs have been identified. Of these, AQP5 plays an important role in the fluid homeostasis and cell volume control in epithelial cells. In an effort to understand the role of AQP5 in testis, we investigated the expression of AQP5 in developing mouse testis, its regulation by estrogen and LH, and the change of steroidogenesis by AQP5 knockdown. Testes and Leydig cells were isolated from male mice at postnatal day (PND) 1, 7, 14, 28, and 56 and estrogen receptor alpha knockout (ERαKO) mice. In mouse testis, AQP5 immunoreactivity was negligible by PND 14. From PND 28 onward, AQP5 immunoreactivity was found in Leydig cells. In ERαKO mouse Leydig cells, AQP5 mRNA level was significantly lower than wild type. In primary adult Leydig cell culture, the expression of AQP5 mRNA was increased by 17β-estradiol (E2) and human chorionic gonadotropin (hCG), but was not changed in ERαKO Leydig cells. Moreover, the expression of AQP5 mRNA was increased by E2 and ERα-selective agonist PPT, but was not changed by ERβ-selective agonist DPN in primary Leydig cells and mLTC-1. In silico analysis and chromatin immunoprecipitation (ChIP) assay revealed that there are putative estrogen response elements (EREs) and cAMP response elements (CRE) in AQP5 promoter region. Testosterone secretion and steroidogenic pathway genes (StAR, Cyp11a1, Cyp17a1, and 3β-HSD6) expression were decreased by AQP5 siRNA in primary Leydig cells. In conclusion, AQP5 expression was coupled with functional differentiation of adult Leydig cells. AQP5 may play an important role in the fluid homeostasis and cell volume control during development of adult Leydig cells. The expression of AQP5 in Leydig cells could be regulated by ERα and LH signaling and AQP5 may be involved in steroidogenesis.

Developing preimplantation embryos require appropriate energy source and express stage specific gene expression for proper development. During early stage embryo development, major energy sources were pyruvate and lactate, after then glucos is used as a main source. Aquaporins (AQPs), also, is suggested as key molecules for blastocoels formation, and energy and meytabolic homeostasis. In this study, we analyzed the expression profiles of AQPs and lactate dehydrogenase (LDH) which convet lacte to pyruvate and back. During development in vivo condition, the expression patterns can be classificed six clusters. AQP2,-3, -5, -8, -9, and -11 were detected at various stages but others were not. Cluster 1 is for an only express at blastocyst stage. Cluster 2 is for an incrase continuosuly from 4-cell stage. Cluster 3 is for a peak at both 4-cell and blastocyst stages. Cluster 4 is for a sharp decrease at morula stage. Cluster 5 is for a sharp decrase at 2-cell and morula stages. Cluster 6 is for continuous decrease after 4-cell stage. Cluster 7 is for no expression AQPs. LDHs expression has three patterns. First is for sharp decrase at both 2-cell stage and morula a stage. Second is for a continuous decrease from 4-cell stage. Third is for an existings until fertilized oocyte, 1-cell stage. Interestingly the expression profiles of AQPs and LDHs were totally changed by in vitro culture. All of the AQPs and LDHs were detected except AQP8. The leves of LDHA and LDHB were significantly decreased in vitro but those of LDHC and LDHD were increased. These results suggest that early stage embryos themselves adaptate to their conditon through modulation of the specific gene expression such as AQPs and LDHs.

Aquaporin5 (AQP5), a water channel plays an important role in the fluid homeostasis and cell volume control in epithelial cells. In an effort to understand fluid homeostasis in the oviduct, tissue specific expression of AQP 5 was examined together with hormonal regulation of AQP5 in the mouse oviduct. To understand the oviductal fluid homeostasis and its regulation by sex steroids, We examined AQP5 expression in mouse oviduct during developmental stage and estrous cycle, and in estrogen receptor α (ERα) knockout mice oviduct. In immature mouse oviduct, expression of AQP5 expression was examined after stimulation with gonadotropins. The effect of ERα agonist (PPT) and ERβ agonist (DPN) on the oviductal expression of AQP5 was examined in ovariectomized mouse. All samples were subjected to realtime-PCR and immunohistochemistry analysis. In oviduct epithelium, AQP5 was largely found in the apicolateral membrane and cytoplasm of ERα-positive non-ciliated cells but weakly expressed in the ciliated cells. Interstitial cells, muscle cells and blood vessels were also weakly positive for AQP5 immunoreactivity. In cyclic female mice oviductal AQP5 mRNA levels were the highest at estrous. In immature mouse oviduct AQP5 mRNA and epithelial immunoreactivity were increased by PMSG, and followed by a decrease after hCG. In ERα KO mice oviduct, AQP5 mRNA levels were significantly lower than those of WT females at diestrous stage. In immature and OVX mouse oviducts, AQP5 mRNA and epithelial immunoreactivity were significantly increased by E2 and PPT. Together, our results suggest the pivotal role of AQP5 in fluid secretion and absorption of water in non-ciliated cells in oviduct. AQP5 gene is tightly activated by estrogen – ERα signaling in non-ciliated cells in oviductal epithelium, mediating the effect of estrogen on gamete transport, fertilization and early embryo development via regulating the fluid homeostasis in oviduct.

It is suggested that carbohydrate metabolites may involve in the development of morula to blastocyst but many of the mechanisms are not unmasked. Two-cell stage embryos were collected and examined the effects of lactate on the development of blastocyst in vitro. The expression profiles of lactate dehydrognase (Ldh) genes and aquaporin (Aqp) genes were analyzed with RT-PCR. The successful development from morula to blastocyst was dependent on lactate concentrations. The expression profiles of Ldh genes were changed by the lactate concentration. Ldha was expressed in morula stage at 10 mM lactate, and in blastocyst stage at lactate free condition. Ldhb was expressed in morula stage at 10 mM and 20 mM lactate, and in blastocyst stage at 10 mM lactate. Aqp genes were also showed different expression patterns by the lactate concentrations. Aqp3 was expressed in hatching embryo at 120 hr post hCG administration (hph) which was cultured in BWW medium and lactate free condition. Aqp7 was expressed in hatching embryos at 120 hph which was cultured at 10 mM lactate condition. Also Aqp8 was expressed in hatching embryo at BWW and 20 mM lactate condition. Aqp9 was expressed in morula at BWW and 10 mM lactate condition, and in blastocyst at BWW. Based on these results, it is suggested that concentration of lactate in the medium and the level of lactate synthesis in embryo is critical factor for blastocoels formation. In addition it is suggested that LDH may involve the AQPs expression in embryos