Red ginseng polysaccharide promotes ferroptosis in gastric cancer cells by inhibiting PI3K/Akt pathway through down-regulation of AQP3.

OBJECTIVE: This study aims to investigate the effect of red ginseng polysaccharide (RGP) on gastric cancer (GC) development and explore its mechanism. METHODS: GC cell lines AGS were treated with varying concentrations of RGP (50, 100, and 200 µg/mL). AGS cells treated with 200 µg/mL RGP were transfected with aquaporin 3 (AQP3) overexpression vector. Cell proliferation, viability, and apoptosis were evaluated by MTT, colony formation assay, and flow cytometry, respectively. Real-time quantitative reverse transcription PCR (qRT-PCR) was used to detect the expression of AQP3. The levels of Fe2+, malondialdehyde, and lactate dehydrogenase were measured using their respective detection kits, and the reactive oxygen species levels was determined by probe 2',7'-dichlorodihydrofluorescein diacetate. The expression of ferroptosis-related protein and PI3K/Akt pathway-related protein were assessed by western blot. In vivo experiments in nude mice were performed and the mice were divided into four groups (n = 5/group) which gavage administrated with 150 mg/kg normal saline, and 75, 150, 300 mg/kg RGP, respectively. Their tumor weight and volume were recorded. RESULTS: RGP treatment effectively inhibited the proliferation and viability of AGS cells in a dosage-dependent manner and induced apoptosis. It induced ferroptosis in AGS cells, as well as inhibiting the expression of PI3K/Akt-related proteins. AQP3 overexpression could reversed the effect of RGP treatment on ferroptosis. Confirmatory in vivo experiments showed that RGP could reduce the growth of implanted tumor, with increased RGP concentration resulting in greater tumor inhibitory effects. CONCLUSION: RGP might have therapeutic potential against GC, effectively inhibiting the proliferation and viability of AGS cells.

Effect of Chimpi, dried citrus peel, on aquaporin-3 expression in HaCaT human epidermal keratinocytes.

BACKGROUND: Chimpi, the dried peel of Citrus unshiu or Citrus reticulata, has various pharmacological effects. Chimpi extract was recently shown to affect the skin, including its inhibitory effect against atopic dermatitis. In this study, we analyzed the effects of Chimpi extract on the functional molecule aquaporin-3 (AQP3), which is involved in water transport and cell migration in the skin. METHODS AND RESULTS: Chimpi extract was added to HaCaT human skin keratinocytes, and the AQP3 expression level was analyzed. A wound healing assay was performed to evaluate the effect of Chimpi extract on cell migration. The components of Chimpi extract and fractions obtained by liquid-liquid distribution studies were added to HaCaT cells, and AQP3 expression was analyzed. Chimpi extract significantly increased AQP3 expression in HaCaT cells at both the mRNA and protein levels. Immunocytochemical staining revealed that Chimpi extract also promoted the transfer of AQP3 to the cell membrane. Furthermore, Chimpi extract enhanced cell migration. Hesperidin, narirutin, and nobiletin did not increase AQP3 levels. Although the components contained in the fractions obtained from the chloroform, butanol, and water layer increased AQP3, the active components could not be identified. CONCLUSIONS: These results reveal that Chimpi extract may increase AQP3 levels in keratinocytes and increase the dermal water content. Therefore, Chimpi extract may be effective for the management of dry skin.

Cold atmospheric plasmas target breast cancer stemness via modulating AQP3-19Y mediated AQP3-5K and FOXO1 K48-ubiquitination.

Cold atmospheric plasma (CAP) is selective against many cancers with little side effect, yet its molecular mechanism remains unclear. Through whole transcriptome sequencing followed by assays in vitro, in vivo and using clinical samples, we propose CAP as a promising onco-therapy targeting cancer stemness via the AQP3/FOXO1 axis. CAP-generated reactive species penetrated cells via AQP3 and suppressed RPS6KA3, a shared kinase of AQP3 and FOXO1. Reduced AQP3-19Y phosphorylation suppressed SCAF11-mediated AQP3-5K K48-ubiquitination that led to sabotaged FOXO1 stability. Inhibited FOXO1 phosphorylation retarded its regulatory activities in maintaining cancer stemness including ALDH1 and IL6. Enhanced anti-cancer efficacy was observed through combining CAP with Atorvastatin in vitro and in vivo. We propose CAP as a 'selective' onco-therapeutic against cancer stemness, with the AQP3/FOXO1 axis being one molecular mechanism. We report SCAF11 as an E3 ubiquitin ligase of both AQP3 and FOXO1, identify AQP3-5K as an AQP3 K48-ubiquitination site, and emphasize the essential role of AQP3-19Y in this process. We reposition Atorvastatin into the onco-therapeutic portfolio by synergizing it with CAP towards enhanced efficacy. We anticipate the efficacy of CAP in targeting malignancies of high stemness alone or as an adjuvant therapy towards the hope of ultimate cancer cure.

Arginine Promotes the Expression of Aquaporin-3 and Water Transport in Porcine Trophectoderm Cells Through NO- and cAMP-Dependent Mechanisms.

BACKGROUND: Dietary supplementation with L-arginine (Arg) has been shown to increase the volume of fetal fluids in gestating swine. Aquaporins (AQPs), known as water channel proteins, are essential for embryonic growth and development. It was not known if Arg mediates water transport through AQPs in porcine conceptus trophectoderm (pTr2) cells. METHODS: pTr2 cells derived from pregnant gilts on day 12 of gestation were cultured in customized Arg-free Dulbecco's modified Eagle's Ham medium (DMEM) supplemented with either 0.00, 0.25, or 0.50 mM Arg. RESULTS: Arg treatment increased water transport and the expression of AQP3, which was abundantly expressed in pTr2 cells at both the mRNA and protein levels. Arg also increased the expression of iNOS and the synthesis of nitric oxide (NO) in pTr2 cells. The presence of Nω-nitro-L-arginine methyl ester hydrochloride (L-NAME; an inhibitor of NO synthase) significantly attenuated the Arg-induced expression of AQP3. Furthermore, 0.50 mM Arg increased the concentrations of cAMP and the abundances of phosphorylated cAMP-dependent protein kinase A (PKA), phosphorylated PKA α/ß/γ, and phosphorylated CREB. These effects of Arg were mimicked by Forskolin (a cell-permeable activator of adenylyl cyclase), but inhibited by H-89 (an inhibitor of cAMP-dependent protein kinase). CONCLUSIONS: The results of this study demonstrate that Arg regulates AQP3 expression and promotes water transport in pTr2 cells through NO- and cAMP-dependent signaling pathways.

Unsaturated fatty acid-enriched extract from Hippophae rhamnoides seed reduces skin dryness through up-regulating aquaporins 3 and hyaluronan synthetases 2 expressions.

BACKGROUND: Seed oil of sea buckthorn (SBT) is well known to contain high amount of polyunsaturated fatty acid (PUFA), and PUFA is generally acknowledged to promote skin hydration by reducing trans-epidermal water loss (TEWL). AIMS: The present study is aimed to investigate that skin hydration offered by SBT seed oil is whether through up-regulating AQP3 or HAS2 expression. METHODS: MTT assay was performed to detect cytotoxicity of SBT seed oil, and then, PCR was carried out to explore whether SBT seed oil can increase AQP3 mRNA expression in normal human epidermis keratinocytes (NHEK) cells or not. Immunofluorescence (IF) and Western blot analysis were used to test the protein level expression of AQP3 and HAS2 influenced by SBT seed oil in NHEK cells or in reconstructed epidermis skin model. RESULTS: According to the result of MTT assay, all test concentration of SBT seed oil showed no cytotoxicity to cells. 10 µg/mL SBT seed oil treatment evidently increased AQP3 mRNA level compared to negative control (NC). IF and Western blot analysis results demonstrated that AQP3 and HAS2 protein levels in NHEK cells treated with 10 µg/mL SBT seed oil were much higher than that of NC. Finally, treatment with 10 µg/mL SBT seed oil substantially up-regulated expression of AQP3 and HAS2 protein in reconstructed epidermis skin model in comparison to NC. CONCLUSIONS: In summary, our study first proved that SBT seed oil can improve skin hydration through increasing AQP3 and HAS2 expressions.

Aquaporin-3 is involved in NLRP3-inflammasome activation contributing to the setting of inflammatory response.

Inflammasomes are large immune multiprotein complexes that tightly regulate the production of the pro-inflammatory cytokines, being dependent on cell regulatory volume mechanisms. Aquaporins (AQPs) are protein channels that facilitate the transport of water and glycerol (aquaglyceroporins) through membranes, essential for cell volume regulation. Although these membrane proteins are highly expressed in monocytes and macrophages, their role in the inflammatory process is still unclear. Here, we investigated the role of aquaglyceroporin AQP3 in NLRP3-inflammasome activation by complementary approaches based either on shRNA silencing or on AQP3 selective inhibition. The latter has been achieved using a reported potent gold-based inhibitor, Auphen. AQP3 inhibition or silencing partially blocked LPS-priming and decreased production of IL-6, proIL-1ß, and TNF-α, suggesting the possible involvement of AQP3 in macrophage priming by Toll-like receptor 4 engagement. Moreover, AQP3-dependent cell reswelling increased IL-1ß release through caspase-1 activation. NLRP3-inflammasome activation induced by reswelling, nigericin, and ATP was also blocked when AQP3 was inhibited or silenced. Altogether, these data point towards AQPs as potential players in the setting of the inflammatory response.

Effects of Allium mongolicum Regel and Its Flavonoids on Constipation.

Constipation is a common bowel disease in adults with the symptoms of dry stool or difficulty passing stool. Compared with medication therapy, patients show more compliance with the diet therapy, and thus the diet therapy normally exhibits better therapeutic effect. Allium mongolicum Regel s a perennial herb of Liliaceae native to Mongolia, Kazakhstan, and China, which is traditionally used for constipation. In this paper, we partly clarify the effectiveness of A. mongolicum on constipation from two aspects, including maintaining colon water content and increasing intestinal transit. In loperamide-induced constipation mice model, nine days oral administration of A. mongolicum 50% ethanolic extract increased luminal side water content and regulated intestinal movement rhythm to normalize stools. The activity at least partly related to down-regulation of colon aquaporins 3 (AQP3) expression, and up-regulation and activation of G protein alpha (Gα) and phosphoinositide 3-kinases (PI3K). Further, activities on intestine movements were tested using compounds isolated from A. mongolicum. Three kinds of major flavonoids significantly increased cellular calcium flux in HCT116 cells and promoted mice intestine smooth muscle contraction. The activity may be related to M choline receptor, µ opioid receptor, 5-HT3 receptor, and inositol 1,4,5-trisphosphate (IP3) receptor.

Efficacy of High Specific Volume Polysaccharide - A New Type of Dietary Fiber - On Molecular Mechanism of Intestinal Water Metabolism in Rats With Constipation.

BACKGROUND The aim of this study was to evaluate the effects of a new type of dietary fiber - high specific volume polysaccharide (HSVP) - on fecal properties, serum vasoactive intestinal peptide (VIP) concentration, intestinal flora count, and expression of the VIP-cAMP-PKA-AQP3 signaling pathway. MATERIAL AND METHODS Compound diphenoxylate was used in 48 healthy Wistar rats to establish a constipation model. Rats were divided into a normal control group, a constipation model group, an HSVP low-dose group, an HSVP medium-dose group, an HSVP high-dose group, and a fructose control group. We used colony count method, ELISA, WB, and RT-PCR to determine fecal moisture content, fecal hardness, fecal passage time, serum VIP concentration, number of intestinal bacteria, and VIP-cAMP-PKA-AQP3 signal pathway protein expression. RESULTS The constipation model was established successfully. HSVP (the medium dose was 10% and the high dose was 15%) improved fecal moisture content, reduced hardness, shortened fecal emptying time, increased intestinal bacteria, reduced serum VIP concentration, downregulated cAMP and PKAm RNA transcription, reduced protein expression, and reduced intestinal AQP3 expression. CONCLUSIONS HSVP improved constipation, increased the number of intestinal bacteria, and elevated expression of the VIP-cAMP-PKA-AQP3 signaling pathway. The mechanism of HSVP in regulating intestinal water metabolism in constipated rats may occur through the VIP-cAMP-PKA-AQP3 signaling pathway, and be closely related to changes in intestinal bacteria. The important role of the brain-gut-microbiome axis in the pathogenesis of constipation has been confirmed in this study.

Circadian Expression of TIMP3 Is Disrupted by UVB Irradiation and Recovered by Green Tea Extracts.

The human skin is the outermost physical barrier and has its own circadian machinery that works either cooperatively with the central clock, or autonomously. Circadian rhythms have been observed in many functions related to epidermal homeostasis including hydration and inflammation, and this functional oscillation is disturbed by ultraviolet radiation (UVR), which is a strong environmental cue. Among the genes estimated to show circadian expression in the skin, metalloproteinase inhibitor 3 (TIMP3), has a rhythmic expression in synchronized human keratinocytes similar to that of the core clock gene PER1 and an epidermal circadian regulatory gene, aquaporin 3 (AQP3) but was antiphase to the core clock gene BMAL1. Tumor necrosis factor-α (TNF-α), the regulatory target of TIMP3 via a disintegrin and metalloproteinase domain 17 (ADAM17), was inversely regulated when TIMP3 expression was downregulated by ultraviolet B (UVB) treatment. When synthetic TIMP3 peptides were applied to the cells, the secretion of TNF-α did not increase following the UVB treatment. Similar to TIMP3 peptides, Camellia sinensis leaf-derived extracts showed a distinguishing efficacy in recovering TIMP3 expression, downregulated by UVB treatment. Together, our results suggest that TIMP3 reversely mediates UVR-induced inflammation by being highly expressed during the daytime; therefore, recovering the circadian expression of TIMP3 using synthetic TIMP3 peptides or bioactive natural ingredients could at least in part inhibit the UVR-induced cellular phenomena.

Honey-Mediated Wound Healing: H2O2 Entry through AQP3 Determines Extracellular Ca2+ Influx.

Since Biblical times, honey has been utilized in "folk medicine", and in recent decades the positive qualities of honey have been re-discovered and are gaining acceptance. Scientific literature states that honey has been successfully utilized on infections not responding to classic antiseptic and antibiotic therapy, because of its intrinsic H2O2 production. In our study, we demonstrated the involvement of H2O2 as a main mediator of honey regenerative effects on an immortalized human keratinocyte cell line. We observed that this extracellularly released H2O2 could pass across the plasma membrane through a specific aquaporin (i.e., AQP3). Once in the cytoplasm H2O2, in turn, induces the entry of extracellular Ca2+ through Melastatin Transient Receptor Potential 2 (TRPM2) and Orai1 channels. Honey-induced extracellular Ca2+ entry results in wound healing, which is consistent with the role played by Ca2+ signaling in tissue regeneration. This is the first report showing that honey exposure increases intracellular Ca2+ concentration ([Ca2+]i), due to H2O2 production and redox regulation of Ca2+-permeable ion channels, opening up a new horizon for the utilization of the honey as a beneficial tool.

Upregulation of aquaporin 3 expression by diterpenoids in Euphorbia pekinensis is associated with activation of the NF-κB signaling pathway in the co-culture system of HT-29 and RAW 264.7 cells.

This study was designed to evaluate the toxic effects of diterpenoids separated from the roots of Euphorbia pekinensis, a type of widely used traditional Chinese medicine. This herb has intestinal toxicity associated with its complex diterpenoids. In this study, the diterpenoids (pekinenin A, pekinenin C, pekinenin F, pekinenin G, yuexiandajisu A, (-)-(1S)-15-hydroxy-18-carboxycembrene) elevated the expression of interleukin 1 beta and tumor necrosis factor alpha in a dose-dependent manner at doses of 6.25, 12.5, and 25 µM in RAW264.7 monocultures. Pekinenin C increased the expression of phosphorylated IκB and phosphorylated p65 in RAW264.7 monocultures, indicating that it stimulated a substantial inflammatory response and activated the nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) signaling pathway. A co-culture model of RAW 264.7 mouse macrophage cells and HT-29 human intestinal epithelial cells was established to study the correlation between inflammation and aquaporin (AQP) expression and to evaluate the toxicity of different diterpenoids from E. pekinensis. Pekinenin C (6.25, 12.5, and 25 µM) increased AQP3 mRNA and protein expression of HT-29 cells in the co-culture system in a dose-dependent manner but not in HT-29 monocultures. AQP3 mRNA and protein expression peaked at 2 and 3 h of HT-29 cells in the co-culture system, respectively. In contrast, their expression peaked more slowly in the monoculture system. After the specific NF-κB inhibitor BAY11-7082 (5, 10, and 20 µM) was added to the co-culture system, the release of cytokines and increased AQP3 expression caused by pekinenin C were inhibited. Comparisons of the representative monomeric compound pekinenin C, diterpenoid monomer mixtures, and total diterpenoids from E. pekinensis showed that the monomer mixtures had the most toxicity. In conclusion, this study demonstrated that E. pekinensis induces inflammation and increases the expression of AQP3, causing disorders of water metabolism, which may lead to gastrointestinal side effects such as diarrhea.

Effect of Yupingfeng granules on the skin barrier in atopic dermatitis mice models.

OBJECTIVE: To investigate effect of Yupingfeng granules, prepared with Chinese Medicines, on the wound healing and on the expression of aquaporin 3 (AQP3) and the skin barrier in the animal models of atopic dermatitis (AD). METHODS: Acute skin lesions of AD models were prepared using 2,4-dinitrochlorobenzo (DNCB) in mice and animals were treated with either Yupingfeng granules or placebo for two weeks. Skin wound healing outcome was assessed by measuring skin thickness, weight (quality) of the skin, and trans-epidermal water loss (TEWL). Expression of AQP3 mRNA and protein was assessed by reverse transcriotion polymerase chain reaction (RT-PCR) and immunoblotting, respectively. RESULTS: Yupingfeng granule treatment resulted in significant acceleration of wound healing with 63.64% efficiency, which was significantly higher than that of placebo granule treatment (31.82%, P < 0.01 by Wilcoxon Rank-sum test). Skin thickness, weight of the wounded skin, and TEWL were significantly higher in the AD models compared to that of normal animals. Treatment with Yupingfeng granules resulted in significant decrease in skin thickness [(937 ± 31) vs (360 ± 21) urn, P < 0.01], weight of the wounded skin [(42 ± 4) vs (24 ± 5) mg, P < 0.01], and TEWL [(30 ± 4) vs (13 ± 4) g•h-1•m-2, P < 0.01]. Yupingfeng granules also significantly down-regulated mRNA and protein expression of AQP3 in the animal models. CONCLUSION: Our findings suggested that Yupingfeng granules could be used in AD treatment.

18ß-glycyrrhetinic acid derivative promotes proliferation, migration and aquaporin-3 expression in human dermal fibroblasts.

Licorice (Glycyrrhiza) species have been widely used as a traditional medicine and a natural sweetener in foods. The 18ß-glycyrrhetinic acid (18ß-GA) is a bioactive compound in licorice that exhibits potential anti-cancer, anti-inflammatory, and anti-microbial activities. Many synthesized derivatives of 18ß-GA have been reported to be cytotoxic and suggested for the treatment of malignant diseases. In this study, we explored the possible pharmacological roles of an 18ß-GA derivative in skin biology using primary human dermal fibroblasts and HaCaT keratinocytes as cell models. We found that this 18ß-GA derivative did not cause cell death, but significantly enhanced the proliferation of dermal fibroblasts and HaCaT keratinocytes. A scratch wound healing assay revealed that the 18ß-GA derivative promoted the migration of fibroblasts. Due to the important role of aquaporin-3 in cell migration and proliferation, we also investigated the expression of aquaporin-3 and found this compound up-regulated the expression of aquaporin-3 in dermal fibroblasts and HaCaT keratinocytes. In dermal fibroblasts, the 18ß-GA derivative induced the phosphorylation of Akt, ERK, and p38. The inhibitor of Akt predominantly suppressed the 18ß-GA derivative-induced expression of aquaporin-3. Collectively, this compound had a positive effect on the proliferation, migration, and aquaporin-3 expression of skin cells, implying its potential role in the treatment of skin diseases characterized by impaired wound healing or dermal defects.

MECHANISMS OF COIX SEED COMPOSITIONS IN THE TREATMENT OF SPLEEN DEFICIENCY AND WET DAMPNESS ZHENG.

BACKGROUND: Coix seed has the functions of fortifying the spleen and inhibiting the dampness. However, it remains unclear which Coix seed compositions is responsible for these functions. Previous investigations have revealed that the main compositions of Coix seed are proteins, polysaccharides, oils and starches. The objectives of this study are to explore which is the most effective compositions in fortifying the spleen and examine how Coix seed works in regulating the water transport on the spleen deficiency and wet dampness (SDWD) rat model. MATERIALS AND METHODS: The rats used were divided into (i) control group, (ii) model group, (iii) decoction group, (iv) protein group, (v) polysaccharide group, (vi) oil group and (vii) starch group. The urine volume, the drinking volume and the water loading index in each group were calculated. Agilent 8*60K array was used for microarray-based gene expression analysis. The differential mRNAs related to the transport activity were screened. qRT-PCR was used to validate the mRNA microarray. RESULTS: The results demonstrated that all treatment groups could decrease the dampness of SDWD rats. mRNA microarray had significant effect on the protein group and the polysaccharide group in regulating the water transport, among which the most significant mRNA was Fabp6, Slc51a, Slc51b, Slc11a2, Slc4a10 and AQP3 respectively. CONCLUSION: The compositions of proteins and polysaccharides had the most significant effect in regulating the water transport of SDWD rat model. The contributing mRNA focused on Fabp, Slc and AQP family.

Danshen extract regulates the expression of aquaporin 3 in human amniotic epithelial cells.

Danshen extract has been used in the treatment of oligohydramnios, however, the mechanism of its action has not been elucidated. Previously, we demonstrated that down-regulation of AQP3 in fetal membranes may contribute to the development of oligohydramnios. In this study, we investigated the effects of Danshen extract on AQP3 expression in human amniotic epithelial cells from term pregnancies with oligohydramnios or those with those with (those with) normovolemic amniotic fluid. Human amniotic epithelial cells from the oligohydramnios group expressed a lower level of AQP3 mRNA and protein than those with normovolemia. Tweleve hour (Twelvehours) of treatment with Danshen extract, in a dose dependent manner, significantly increased the expression of AQP3 in the two groups. However, human amniotic epithelial cells from the oligohydramnios patients showed a greater sensitivity to the treatment of Danshen extract. These data provide a molecular basis for the treatment of patients with oligohydraminos.

Aquaporin 3 Expression Induced by Salvia Miltiorrhiza via ERK1/2 Signal Pathway in the Primary Human Amnion Epithelium Cells from Isolated Oligohydramnios.

Salvia miltiorrhiza is one of the most common Chinese herbal drugs, which is effective to treat oligohydramnios. In this study, the aim was to investigate how Salvia miltiorrhiza regulate aquaporin 3 expression in the human amnion epithelial cells (hAECs) with normal amniotic fluid volume or isolated oligohydramnios, whether via extracellular signal regulated kinase1/2 (ERK1/2) signal transduction pathway or not. Primary hAECs cultures from 120 patients were incubated with Salvia miltiorrhiza or/and ERK1/2 inhibitor-- U0126. Localization of aquaporin 3 was detected by immunohistochemistry and the expression of total ERK1/2, phospho-ERK1/2 (p-ERK1/2) and aquaporin 3 was detected by Western blot. The results were: (1) In hAECs with normal amniotic fluid volume, treatment with 10 µmol/L of U0126 for 6 h resulted in the optimal inhibition of p-ERK1/2 (P<0.05). However, the expression of total ERK1/2 or aquaporin 3 did not significantly change after different concentrations or time of U0126 treatment. Salvia miltiorrhiza significantly up-regulated aquaporin 3 expression, which was not affected by U0126. (2) In hAECs with isolated oligohydramnios, treatment with 5 µmol/L of U0126 for 2 h resulted in the optimal inhibition of p-ERK1/2 and the lowest expression of aquaporin 3 (P<0.05). Moreover, Salvia miltiorrhiza significantly up-regulated aquaporin 3 expression, which was obviously blocked by U0126. These results suggest that Salvia miltiorrhiza may regulate aquaporin 3 expression in hAECs. In addition, in hAECs with isolated oligohydramnios, Salvia miltiorrhiza may regulate the expression of aquaporin 3 via the ERK1/2 signal transduction pathway, which provides a novel thread to the improved treatment for isolated oligohydramnios.

Effect of intense pulsed light on the expression of aquaporin 3 in rat skin.

Intense pulsed light (IPL) technology has been popularly employed in clinical treatments for dermatological and cosmetic purposes in recent years; yet, the underlying mechanisms of its functions are not fully elucidated. On the other hand, aquaporin (AQP) 3, a member of a subgroup of the aquaporin family that transports both water and small solutes, such as glycerol, has been documented to play an important role in the skin homeostasis. We thus examined the possible involvement of AQP3 in the functional mechanisms of IPL irradiation. Rat dorsal skin areas were irradiated one to three times with IPL at doses of 15, 25, and 35 J/cm2. Skin specimens were collected 7 days after the final irradiation and analyzed for changes in histology, skin hydration, mRNA, and protein expressions of AQP3. IPL induced no significant variations in the mRNA expression levels. Twice or thrice irradiation at the dose of 25 or 35 J/cm2 significantly enhanced AQP3 protein expression. Immunofluorescence study revealed that AQP3 was mainly localized to keratinocyte membranes in the basal layer of epidermis, and the localization was unaltered by IPL. In addition, the pattern of IPL-induced changes in skin hydration was generally coincided with the expression profile of AQP3. These results suggest the possibility that one of the functional mechanisms of IPL might be related to the regulation of AQP3 protein expression.

Profiles of hypothalamus-pituitary-interrenal axis gene expression in the parr and smolt stages of rainbow trout, Oncorhynchus mykiss: effects of recombinant aquaporin 3 and seawater acclimation.

The objective of this investigation was to quantify how the hypothalamus-pituitary-interrenal (HPI) axis in the rainbow trout, Oncorhynchus mykiss (parr/smolt), responds to salinity changes during transfer from freshwater (FW) to seawater (SW) and recombinant aquaporin 3 (rAQP3) injection. mRNA expression levels of HPI axis genes [corticotropic-releasing hormone (CRH) and adrenocorticotropic hormone (ACTHα and ACTHß)] significantly increased when the fish were transferred from FW to SW (parr: 16.4-, 13.2-, 21.4-, and 11.9-fold higher than FW; smolt: 2.3-, 2.7-, 13.6-, and 6.2-fold higher than FW, respectively). Furthermore, and the plasma ACTH, Na(+), Cl(-), and K(+) levels were the highest at 50% SW. Moreover, these parameters were significantly lower in the rAQP3-treated group than those in the control (parr: 2.0-, 2.4-, 2.1-, and 2.0-fold lower than SW; smolt: 4.2-, 1.9-, 2.4-, and 2.3-fold lower than SW, respectively). Hence, HPI axis genes may play a role in SW adaptation during migration from FW to SW environments. We showed that there was a negative correlation between rAQP3, HPI axis genes, and ion levels when the fish were transferred to SW, with levels being significantly lower in the rAQP3-injected group. Hence, cortisol appears to be a stress hormone and plasma Na(+) and Cl(-) levels significantly increased when the fish were transferred to SW, with levels being significantly lower in the rAQP3-treated group. These results indicate that rAQP3 modulates the HPI axis and ion transportation in rainbow trout.

Rhubarb tannins extract inhibits the expression of aquaporins 2 and 3 in magnesium sulphate-induced diarrhoea model.

Tannins, a group of major active components of Chinese rhubarb and widely distributed in nature, have a significant antidiarrhoeal activity. Aquaporins (AQPs) 2 and 3 play important roles in regulating water transfer during diarrhoea. The present study aims to determine the effect of the total tannins extract of rhubarb on aquaporins (AQPs) 2 and 3 in diarrhoea mice and HT-29 cells both induced by magnesium sulphate (MgSO4). Our results showed that rhubarb tannins extract (RTE) significantly decreased the faecal water content in colon and evaluation index of defecation of diarrhoea mice. Interestingly, RTE could markedly reduce the mRNA and protein expression levels of AQPs 2 and 3 in apical and lateral mucosal epithelial cells in the colons of diarrhoea mice and HT-29 cells both induced by MgSO4 in a dose-dependent manner. Furthermore, RTE suppressed the production of cyclic monophosphate- (cAMP-) dependent protein kinase A catalytic subunits α (PKA C-α) and phosphorylated cAMP response element-binding protein (p-CREB, Ser133) in MgSO4-induced HT-29 cells. Our data showed for the first time that RTE inhibit AQPs 2 and 3 expression in vivo and in vitro via downregulating PKA/p-CREB signal pathway, which accounts for the antidiarrhoeal effect of RTE.

The laxative effect of emodin is attributable to increased aquaporin 3 expression in the colon of mice and HT-29 cells.

Emodin (1,3,8-trihydroxy-6-methylanthraquinone) is a stimulant laxative and used to treat constipation. Aquaporin 3 (AQP3) plays an important role in regulating water transfer in the colon. In the study, we investigated whether the laxative effect of emodin is associated with the regulation of AQP3 in the colon. Our results showed that treatment with emodin increased the fecal water content in the colon of mice and evaluation index of defecation in a dose-dependent manner. More interestingly, emodin significantly increased the AQP3 protein and mRNA expression both in the colon of mice and in human intestinal epithelial cells (HT-29). Mechanistically, emodin obviously up-regulated the cyclic adenosine monophosphate (cAMP)-dependent protein kinase A catalytic subunits α (PKA C-α) and phosphorylated cAMP response element-binding protein (p-CREB Ser133) expression in HT-29 cells. These results suggest that the laxative effect of emodin is associated with the increased expression of AQP3 by up-regulating PKA/p-CREB signal pathway.