AQP1 Research Articles

Advanced Glycation End Products and Activation of Toll-like Receptor-2 and -4 Induced Changes in Aquaporin-3 Expression in Mouse Keratinocytes.

Prolonged inflammation and impaired re-epithelization are major contributing factors to chronic non-healing diabetic wounds; diabetes is also characterized by xerosis. Advanced glycation end products (AGEs), and the activation of toll-like receptors (TLRs), can trigger inflammatory responses. Aquaporin-3 (AQP3) plays essential roles in keratinocyte function and skin wound re-epithelialization/re-generation and hydration. Suberanilohydroxamic acid (SAHA), a histone deacetylase inhibitor, mimics the increased acetylation observed in diabetes. We investigated the effects of TLR2/TLR4 activators and AGEs on keratinocyte AQP3 expression in the presence and absence of SAHA. Primary mouse keratinocytes were treated with or without TLR2 agonist Pam3Cys-Ser-(Lys)4 (PAM), TLR4 agonist lipopolysaccharide (LPS), or AGEs, with or without SAHA. We found that (1) PAM and LPS significantly upregulated AQP3 protein basally (without SAHA) and PAM downregulated AQP3 protein with SAHA; and (2) AGEs (100 µg/mL) increased AQP3 protein expression basally and decreased AQP3 levels with SAHA. PAM and AGEs produced similar changes in AQP3 expression, suggesting a common pathway or potential crosstalk between TLR2 and AGEs signaling. Our findings suggest that TLR2 activation and AGEs may be beneficial for wound healing and skin hydration under normal conditions via AQP3 upregulation, but that these pathways are likely deleterious in diabetes chronically through decreased AQP3 expression.

Metabolomic Analysis of Stephania tetrandra-Astragalus membranaceus Herbal Pair-Improving Nephrotic Syndrome Identifies Activation of IL-13/STAT6 Signaling Pathway.

The Stephania tetrandra−Astragalus membranaceus herbal pair (FH) is a classic herbal pair widely used in the treatment of nephrotic syndrome (NS). The effects of Stephania tetrandra (FJ) and Astragalus membranaceus (HQ) on NS have been reported, but the mechanism of their combination on the improvement of NS are still unclear. The NS model was established by injecting adriamycin into the tail vein. FH intervention reduced the levels of serum triglyceride, total cholesterol, interleukin-6 (IL-6), blood urea nitrogen (BUN), urinary protein, and the gene expression levels of aquaporin 2 (AQP2) and arginine vasopressin (AVP) in NS rats. In addition, FH improved kidney injury in NS rats by inhibiting the expression of interleukin 13 (IL-13), phospho-signal transducers, and activators of transcription 6 (p-STAT6), Bax, cleaved-caspase3, while promoting the expression of Bcl-2. By comprehensive comparison of multiple indexes, the effects of FH on lipid metabolism, glomerular filtration rate, and inflammation were superior to that of FJ and HQ. Metabonomic studies showed that, compared with FJ and HQ, FH intervention significantly regulated tricarboxylic acid (TCA) cycle, cysteine and methionine metabolism, and alanine, aspartic acid and glutamic acid metabolism. Pearson correlation analysis showed that succinic acid and L-aspartic acid were negatively correlated with urinary protein, cystatin C (Cys C) and BUN (p < 0.05). In summary, FH could reduce renal injury and improve NS through inhibiting the IL-13/STAT6 signal pathway, regulating endogenous metabolic pathways, such as TCA cycle, and inhibiting the expression of AQP2 and AVP genes. This study provides a comprehensive strategy to reveal the mechanism of FH on the treatment of NS, and also provides a reasonable way to clarify the compatibility of traditional Chinese medicine.

Effects of Elevated Intraocular Pressure on Retinal Ganglion Cell Density and Expression and Interaction of Retinal Aquaporin 9 and Monocarboxylate Transporters

Introduction: Astrocyte-to-neuron lactate shuttle (ANLS) plays an important role in the energy metabolism of neurons, including retinal ganglion cells (RGCs). Aquaporin 9 (AQP9), which is an aquaglyceroporin that can transport lactate, may be involved in ANLS together with monocarboxylate transporters (MCTs) to maintain RGC function and survival. This study aimed to investigate the impact of elevated intraocular pressure (IOP) on AQP9-MCT interaction and RGC survival. Methods: IOP was elevated in Aqp9 knock-out (KO) mice and wild-type (WT) littermates by anterior chamber microbead injection. RGC density was measured by TUBB3 immunostaining on retinal flat mounts. Immunolabeling, immunoblot, and immunoprecipitation were conducted to identify and quantitate expressions of AQP9, MCT1, MCT2, and MCT4 in whole retinas and ganglion cell layer (GCL). Results: Aqp9 KO and WT mice had similar RGC density at baseline. Microbead injection increased cumulative IOP by approximately 32% up to 4 weeks, resulting in RGC density loss of 42% and 34% in WT and Aqp9 KO mice, respectively, with no statistical difference. In the retina of WT mice, elevated IOP decreased the amount of AQP9, MCT1, and MCT2 protein and changed the AQP9 immunoreactivity and reduced MCT1 and MCT2 immunoreactivities in GCL. Meanwhile, it decreased MCT1 and increased MCT2 that interact with AQP9, without affecting MCT4 expression. Aqp9 gene deletion increased baseline MCT2 expression in the GCL and counteracted IOP elevation regarding MCT1 and MCT2 expressions. Conclusion: The compensatory upregulation of MCT1 and MCT2 with Aqp9 gene deletion and ocular hypertension may reflect the need to maintain lactate transport in the retina for RGC survival.

Magnesium Compounds Increase Aquaporin‐3 in Human Epidermal Keratinocyte HaCaT Cells

Several studies have shown that magnesium can be a useful tool in preventing various skin disorders. However, the mechanism remains unclear. In this study, we analyzed the mechanism by which magnesium improves skin function, focusing on the water channel aquaporin‐3 (AQP3), which is a cutaneous functional molecule. Magnesium compounds (magnesium acetate, magnesium chloride, magnesium sulfate, and magnesium lactate) were added to human epidermal keratinocyte HaCaT cells, and the mRNA and protein expression levels of AQP3 were analyzed. We also investigated the mechanism by which magnesium acetate regulates AQP3 expression. Several magnesium compounds were individually added to HaCaT cells, and 6 hours later, the AQP3 mRNA expression level in the treated cells was significantly increased compared to that in the control cells. Among the magnesium compounds, magnesium acetate had a strong effect and markedly increased the AQP3 mRNA expression level by approximately 3.5 times and the protein expression level by approximately 3 times. Magnesium acetate also enhanced the phosphorylation of cAMP response element‐binding protein (CREB), which is involved in AQP3 transcription. Furthermore, the increase in AQP3 expression levels induced by magnesium acetate was suppressed by treatment with the protein kinase A (PKA) inhibitor H‐89. Magnesium compounds increased the expression level of AQP3 in epidermal keratinocytes and may have a skin‐moisturizing effect. The magnesium‐induced phosphorylation of CREB may be associated with the activation of the cAMP/PKA pathway. Overall, magnesium compounds may be useful for the prevention and treatment of age‐associated xeroderma.

Study on the Resolving Phlegm Effect of D-Limonene in Mice with Spleen Deficiency and Phlegm-Dampness Syndrome

Objective: According to Traditional Chinese Medicine theory, spleen deficiency and phlegm-dampness syndrome (SDPDS) are caused by abnormal water metabolism in the body because of spleen dysfunction. The purpose of this article was to evaluate the efficacy of D-limonene (DL) in resolving phlegm in mice with SDPDS from the perspective of regulating the level of aquaporin 3 (AQP3). Methods: The model of SDPDS was induced in mice using the multifactor modeling method, which combines internal and external dampness. An artificial climate box was used to create a humid environment, whereas the irregular diet was caused by different feeding methods on odd-even days. The mice were divided into blank control, model group, DL low-dose, DL high-dose, and positive groups. The mice were modeled and treated for 7 day. Levels of gastrin and amylase (AMS) in the serum, mucus secretion in the trachea, and AQP3 in the tissue near the gastric cardia. Results: DL significantly reduced mucus secretion in the trachea (P &lt; 0.001). It also increased the level of AMS in the serum (P &lt; 0.01) and decreased the level of AQP3 in the gastric tissue (P &lt; 0.01). Conclusions: Mice with SDPDS exhibited disturbed water metabolism and significantly increased AQP3 levels. DL can restore the levels of AQP3 and plays an important role in resolving phlegm. This study may also help expand the efficacy of natural drugs containing DL and improve the utilization of natural drug resources.

PS-BPB05-3: SERINE PROTEASE INHIBITION EXERTS AQUARETIC EFFECT AND DECREASES URINARY EXOSOMAL AQP2 LEVELS

Objective: Serine proteases (SPs) play pivotal roles in various physiological processes. In the kidney, it is reported that the epithelial sodium channel (ENaC) is activated via the proteolytic cleavage of α and γ subunits by SPs. We previously reported that a synthetic SP inhibitor camostat mesilate (CM) suppressed the cleavage of γENaC, thereby decreasing sodium reabsorption and blood pressure in aldosterone-infused rats. These results suggest the important roles of SPs within the kidney in the regulation of sodium homeostasis and blood pressure. Here, we aimed to identify novel physiological roles of SPs in the renal tubule and understand the mechanism of actions of SP inhibitors by administering CM into healthy rats. Design and method: Six-week-old male Sprague-Dawley rats were divided into control and CM groups. CM group rats were subcutaneously implanted with sustained-release pellets of CM (14 mg/day). After 24 h urine collection was performed, rats were sacrificed at day 7 to obtain blood and kidney samples. Urine volume was measured during the experimental period, and blood and urinary electrolytes, blood vasopressin, and renal tissue osmolality were measured. Protein expression of SPs and aquaporin-2 (AQP2) was analyzed by Western blotting. Results: CM significantly increased urine volume by approximately two-fold throughout the experimental period [urine volume (mL/day): control, 15.5 ± 2.4; CM, 30.6 ± 5.8], in a urinary sodium and osmolyte excretion-independent manner, which indicated that free water excretion had occurred. The vasopressin, potassium, and calcium levels in the blood and osmolality in the inner medulla, which affect free water reabsorption in the renal tubule, remained unchanged after CM administration. CM decreased urinary exosomal AQP2 excretion, suggesting that the AQP2 activity was suppressed in the collecting duct. These changes were reversed by the infusion of desmopressin. Such water diuretic action caused by CM was independent of its action on prostasin and TMPRSS4, which are serine proteases associated with sodium and water homeostasis, respectively. Conclusion: Our results revealed the association of SP inhibition with free water diuresis in the kidney and demonstrated that CM administration resulted in the downregulation of AQP2. The current findings suggest that SP inhibitors could become a new class of aquaretic drugs.

Blueberry Stem Extract Prevents Lacrimal Hyposecretion in Non-obese Diabetic Mice via Activation of AMPK.

Tears secreted from the lacrimal gland are essential for preserving the ocular surface. Thus, dysfunction of the lacrimal gland in Sjögren's syndrome (SS) can lead to dry eye, resulting in a reduced quality of life. We previously reported that blueberry 'leaf' water extract prevents lacrimal hyposecretion in male non-obese diabetic (NOD) mice in a SS-like model. In this study, we investigated the effect of blueberry 'stem' water extract (BStEx) on lacrimal hyposecretion in NOD mice. Male NOD mice were fed 1% BStEx or control (AIN-93G) for 2, 4, or 6 weeks from 4 weeks of age. Pilocarpine-induced tear secretion was measured using a phenol red-impregnated thread. The lacrimal glands were histologically evaluated by HE staining. Inflammatory cytokine levels in the lacrimal glands were measured using ELISA. Immunostaining was performed to examine aquaporin 5 (AQP5) localization. The expression levels of autophagy-related proteins, AQP5, and phosphorylated AMPK were measured using western blotting. After feeding BStEx to mice for 4 or 6 weeks, tear volume was observed to have increased in the BStEx group compared with that in the control group. There were no significant differences in inflammatory cell infiltration, autophagy-related protein expression, or the localization and expression of AQP5 in the lacrimal glands between the two groups. In contrast, AMPK phosphorylation increased in the BStEx group. BStEx prevented lacrimal hyposecretion in the SS-like model of male NOD mice, probably by opening tight junctions via the activation of AMPK in lacrimal acinar cells.

Protective effect of selenium and vitamin C on the fertility of male rats given penconazole.

Penconazole is used in agriculture and human and veterinary medicine applications. It has been included in the acute toxicity hazard category by the WHO. This study examines the protective effect of selenium and vitamin C on the fertility of male rats given penconazole. Nine groups of rats were given penconazole at concentrations of 50 and 75 mg/ml and selenium and vitamin C at concentrations of 0.5 and 100 mg/ml, respectively. Serum levels of LH and FSH were measured with ELISA kits; β-actin, GPX4, AQP7, PRM2, and BAX gene expression was evaluated with real-time PCR performed on the left testis of each rat. LH, FSH, and testosterone levels were lower in the groups given penconazole (50 and 75 mg/kg). Histopathology showed that the groups given penconazole had the lowest number of spermatogonia and primary spermatocytes; these numbers were greater in the groups receiving penconazole together with selenium or vitamin C; and the highest counts were observed in separate groups given Se and vitamin C. GPX4, AQP7, PRM2 and BAX gene expression in the groups receiving penconazole was different from controls and was modulated by treatment with selenium or vitamin C. This study showed that antioxidant compounds have a strengthening effect on the reproductive system and can mitigate the destructive effects of chemical fungicides.

Xuanhuang Runtong Tablets Relieve Slow Transit Constipation in Mice by Regulating TLR5/IL-17A Signaling Mediated by Gut Microbes.

This study aims to investigate the regulation effects of Xuanhuang Runtong tablets (XHRTs) on intestinal microbes and inflammatory signal toll receptor 5 (TLR5)/interleukin-17A (IL-17A) in STC mice. First, high-performance liquid chromatography (HPLC) was used to verify the composition of XHRT and quality control. Then, the defecation ability of STC mice was evaluated by measuring fecal water content and intestinal transit function. The pathological examination of colonic mucosa was observed by Alcian Blue and periodic acid Schiff (AB-PAS) staining. 16S ribosomal DNA (16S rDNA) genes were sequenced to detect the fecal microbiota. Western blotting, immunofluorescence, and real-time fluorescence quantitative PCR (qRT-PCR) were applied to detect the expression of aquaporin 3 (AQP3), connexin 43 (Cx43), TLR5, and IL-17A. The defecation function of the STC mice was significantly decreased. The amount of mucus secretion and the thickness of the colonic mucus layer were decreased, and the number of microbial species in the intestinal wall, such as Firmicutes/Bacteroidetes, anaerobic bacteria, and Alistipes, were also decreased. In addition, the expression of AQP3 and Cx43 was disordered, and the inflammatory factorsTLR5 and IL-17A were activated in the colon. The changes in the above indicators were significantly reversed by XHRT. This study demonstrates that XHRT provides a new strategy for the treatment of slow transit constipation by regulating the activation of the intestinal inflammatory signal TLR5/IL-17A mediated by gut microbes.

PS-B05-6: FABRY DISEASE MOUSE IS RESISTANT TO HIGH-SALT DIET-INDUCED HYPERTENSION PROBABLY VIA DYSFUNCTIONAL SODIUM TRANSPORTS AND AQUAPORIN 2

Background: Fabry disease is a rare X-linked lysosomal storage disorder resulting from an error in glycosphingolipid metabolism caused by the GLA gene mutation. Patients with Fabry disease often have near normal or even low systemic blood pressure although the mechanism underlying such observed finding remains unexplained. This study examined whether a high salt intake could affect transport of sodium and water and induce hypertension in mice with Fabry disease. Methods: Fabry disease model mice (B6;129-Glatm1Kul/J) and wild-type (WT) mice received 8% or normal NaCl salt diet for 2 weeks. Results: A high-salt diet for 2 weeks generated higher blood pressure in WT mice but not in Fabry disease mice. Free water clearance (FWC) and electrolyte free water clearance (EFWC) in groups fed with a high salt diet were lower than those in groups fed with a normal salt diet. Both high salt-fed WT and Fabry disease mice had decreased gamma-subunit of epithelial Na channel (ENaC) compared with normal salt-fed groups. In Fabry disease mice fed a high-salt diet, there was an decrease in renal expressions of Na+/H+ exchanger isoform 3 (NHE3) and Na+-Cl- cotransporter (NCC) compared with WT mice fed a high-salt diet. Although renal expression of vasopressin V2 receptor (V2R) was upregulated in Fabry mice fed with a high salt diet, renal aquaporin 2 (AQP2) level failed to increase up to the level in WT mice fed with a high salt diet. Conclusion: These findings suggest that the decreased expression of NHE3 and NCC and impaired response of AQP2 in kidneys of Fabry disease to a salt load could be one of mechanisms by which Fabry disease could have resistance to the development of hypertension.

Aquaporins in Diabetes Insipidus.

Disruption of water and electrolyte balance is frequently encountered in clinical medicine. Regulating water metabolism is critically important. Diabetes insipidus (DI) presented with excessive water loss from the kidney is a major disorder of water metabolism. To understanding the molecular and cellular mechanisms and pathophysiology of DI and rationales of clinical management of DI is important for both research and clinical practice. This chapter will first review various forms of DI focusing on central diabetes insipidus (CDI) and nephrogenic diabetes insipidus (NDI). This is followed by a discussion of regulatory mechanisms underlying CDI and NDI, with a focus on the regulatory axis of vasopressin, vasopressin receptor 2 (V2R) and the water channel molecule, aquaporin 2 (AQP2). The clinical manifestation, diagnosis, and management of various forms of DI will also be discussed with highlights of some of the latest therapeutic strategies that are developed from in vitro experiments and animal studies.

Effects of retinoid-loaded hyaluronic acid nanomicelles on vaginal epithelium in a murine menopause model.

This study aimed to develop hyaluronic acid (HA)-based, retinoic acid (RA)-containing nanomicelles and to investigate the effects of these newly developed nanomicelles on regeneration of the vaginal epithelium and aquaporin 3 (AQP3) expression in a murine menopause model. The HA-based, RA-loaded nanomicelles were developed, and the RA-loading rate, encapsulation efficiency, and hydrodynamic diameter were measured. Female BALB/c mice (8 weeks; n=30) were divided into control and experimental groups. Menopause was established in the experimental group by removing both ovaries. The experimental group was further divided into an ovariectomy group, an HA-C18 vehicle group, and an HA-C18-RA group (2.5 µg per mouse); vaginal administration of HA-C18 or HA-C18-RA was performed once daily. After 4 weeks of treatment, murine vaginal tissue was removed, and histological analysis was performed. Three drug-loaded nanomicelles were synthesized: the RA content in HA-C18-RA-10, HA-C18-RA-20, and HA-C18-RA-30 was 3.13%, 2.52%, and 16.67%, respectively, and the RA encapsulation efficiency was 95.57%, 83.92%, and 93.24%, respectively. In the experimental versus control group, serum estrogen levels were significantly reduced, and the vaginal mucosal epithelial layer was significantly thinner. After 4 weeks of treatment, the thickness of the vaginal mucosal epithelial layer and AQP3 expression was increased in the HA-C18-RA group compared with the HA-C18 vehicle group. The newly developed HA-based nanomicelles containing RA resulted in vaginal epithelial recovery and increased AQP3 expression. The results may contribute to the development of functional vaginal lubricants or moisturizers for the treatment of vaginal dryness.

New developments and concepts in the diagnosis and management of diabetes insipidus (AVP-deficiency and resistance).

Diabetes insipidus (DI) is a disorder characterised by the excretion of large amounts of hypotonic urine, with a prevalence of 1 per 25,000 population. Central DI (CDI), better now referred to as arginine vasopressin (AVP)-deficiency, is the most common form of DI resulting from deficiency of the hormone AVP from the pituitary. The less common nephrogenic DI (NDI) or AVP-resistance develops secondary to AVP resistance in the kidneys. The majority of causes of DI are acquired, with CDI developing when more than 80% of AVP-secreting neurons are damaged. Inherited/familial CDI causes account for approximately 1% of cases. Although the pathogenesis of NDI is unclear, more than 280 disease-causing mutations affecting the AVP2 protein or AVP V2 receptor, as well as in aquaporin 2 (AQP2), have been described. Although the cAMP/protein kinase A pathway remains the major regulatory pathway of AVP/AQP2 action, in vitro data have also revealed additional cAMP independent pathways of NDI pathogenesis. Diagnosing partial forms of DI, and distinguishing them from primary polydipsia, can be challenging, previously necessitating the use of the water deprivation test. However, measurements of circulating copeptin levels, especially after stimulation, are increasingly replacing the classical tests in clinical practice because of their ease of use and high sensitivity and specificity. The treatment of CDI relies on desmopressin administration, whereas NDI requires the management of any underlying diseases, removal of offending drugs and, in some cases, administration of diuretics. A better understanding of the pathophysiology of DI has led to novel evolving therapeutic agents that are under clinical trial.

The effect of kiwi berry (&lt;i&gt;Actinidia arguta&lt;/i&gt;) on preventing and alleviating loperamide-induced constipation

This research aimed to study the preventive and relieving outcomes of kiwi berry on constipation. The administration of kiwi berries to mice resulted in a significant increase in body weight gain of 148.2% compared to mice that were constipated. The number of stools and the water content of stools both increased by 138.5% and 106.5%, respectively. The gastrointestinal transit rate increased by 45.3%, and the time it took for the first dark stool to form decreased by 57.5%. The levels of the excitability neurotransmitters were found to be higher in the group that had been given kiwi berries in comparison to the group that had been given loperamide. The opposite results were produced by vasoactive intestinal peptide (VIP) and aquaporin-3 (AQP3). In addition, kiwi berry consumption may lessen epithelial cell apoptosis and promote colon health. All the results point to kiwi berries as an extremely promising food supplement for the prevention and relief of constipation in the future since they successfully prevent and alleviate constipation brought on by loperamide.

Overexpression of aquaporin-5 (AQP5) in pulmonary epithelial cells suppresses sepsis-induced edema by inhibiting epithelial apoptosis

Overexpression of aquaporin-5 (AQP5) in pulmonary epithelial cells suppresses sepsis-induced edema by inhibiting epithelial apoptosis

Ablation of AQP5 gene in mice leads to olfactory dysfunction caused by hyposecretion of Bowman's gland.

Smell detection depends on nasal airflow, which can make absorption of odors to the olfactory epithelium by diffusion through the mucus layer. The odors then act on the chemo-sensitive epithelium of olfactory sensory neurons (OSNs). Therefore, any pathological changes in the olfactory area, for instance, dry nose caused by Sjögren's Syndrome (SS) may interfere with olfactory function. SS is an autoimmune disease in which aquaporin (AQP) 5 autoantibodies have been detected in the serum. However, the expression of AQP5 in olfactory mucosa and its function in olfaction is still unknown. Based on the study of the expression characteristics of AQP5 protein in the nasal mucosa, the olfaction dysfunction in AQP5 knockout (KO) mice was found by olfactory behavior analysis, which was accompanied by reduced secretion volume of Bowman's gland by using in vitro secretion measure system, and the change of acid mucin in nasal mucus layer was identified. By excluding the possibility that olfactory disturbance was caused by changes in OSNs, the result indicated that AQP5 contributes to olfactory functions by regulating the volume and composition of OE mucus layer, which is the medium for the dissolution of odor molecules. Our results indicate that AQP5 can affect the olfactory functions by regulating the water supply of BGs and the mucus layer upper the OE that can explain the olfactory loss in the patients of SS, and AQP5 KO mice might be used as an ideal model to study the olfactory dysfunction.

Aquaporin 9 is involved in CRC metastasis through DVL2-dependent Wnt/β-catenin signaling activation.

Aquaporin 9 (AQP9) is permeable to water or other small molecules, and plays an important role in various cancers. We previously found that AQP9 was related to the efficacy of chemotherapy in patients with colorectal cancer (CRC). This study aimed to identify the role and regulatory mechanism of AQP9 in CRC metastasis. The clinical significance of AQP9 was analysed by using bioinformatics and tissue microarray. Transcriptome sequencing, Dual-Luciferase Reporter Assay, Biacore, and co-immunoprecipitation were employed to demonstrate the regulatory mechanism of AQP9 in CRC. The relationship between AQP9 and CRC metastasis was verified in vitro and in vivo by using real-time cell analysis assay, high content screening, and liver metastasis models of nude mice. We found that AQP9 was highly expressed in metastatic CRC. AQP9 overexpression reduced cell roundness and enhanced cell motility in CRC. We further showed that AQP9 interacted with Dishevelled 2 (DVL2) via the C-terminal SVIM motif, resulting in DVL2 stabilization and theWnt/β-catenin pathway activation. Additionally, we identified the E3 ligase neural precursor cell expressed developmentally downregulated 4-like (NEDD4L) as a modulator regulating the ubiquitination and degradation of AQP9. Collectively, our study revealed the important role of AQP9 in regulating DVL2 stabilization and Wnt/β-catenin signaling to promote CRC metastasis. Targeting the NEDD4L-AQP9-DVL2 axis might have therapeutic usefulness in metastatic CRC treatment.

SOX2-positive retinal stem cells are identified in adult human pars plicata by single-cell transcriptomic analyses.

Stem cell therapy is a promising strategy to rescue visual impairment caused by retinal degeneration. Previous studies have proposed controversial theories about whether in situ retinal stem cells (RSCs) are present in adult human eye tissue. Single-cell RNA sequencing (scRNA-seq) has emerged as one of the most powerful tools to reveal the heterogeneity of tissue cells. By using scRNA-seq, we explored the cell heterogeneity of different subregions of adult human eyes, including pars plicata, pars plana, retinal pigment epithelium (RPE), iris, and neural retina (NR). We identified one subpopulation expressing SRY-box transcription factor 2 (SOX2) as RSCs, which were present in the pars plicata of the adult human eye. Further analysis showed the identified subpopulation of RSCs expressed specific markers aquaporin 1 (AQP1) and tetraspanin 12 (TSPAN12). We, therefore, isolated this subpopulation using these two markers by flow sorting and found that the isolated RSCs could proliferate and differentiate into some retinal cell types, including photoreceptors, neurons, RPE cells, microglia, astrocytes, horizontal cells, bipolar cells, and ganglion cells; whereas, AQP1- TSPAN12- cells did not have this differentiation potential. In conclusion, our results showed that SOX2-positive RSCs are present in the pars plicata and may be valuable for treating human retinal diseases due to their proliferation and differentiation potential.

The Effects of Tribulus Terrestris on Aquaporin-1 (AQP1) Immunolocalization in Small and Large Intestines of Mice

This study aimed to examine the effects of Tribulus Terrestris on Aquaporin-1 (AQP1) immunolocalization in the small and large intestines of mice. A total of 16 male BALB/c mice were used in the study. The control and experiment groups consisted of randomly selected mice, with each group containing eight animals. Small and large intestine tissues of mice were taken under deep anesthesia at the end of the study. Routine histological and immunohistochemical methods were applied on the intestinal tissues obtained at the end of the study. The analyses indicated that the intestinal tissues of all groups had a normal histology, and there was a statistically significant difference between the numbers of goblet cells of the control and Tribulus Terrestris (TT) groups in the ileum, cecum, colon and rectum. AQP1immunoreactivity was detected in the small and large intestines of both groups. AQP1immunoreactivity increased in the apical cytoplasm of the intestinal villus and crypt epithelium cells in the small intestine of the TT group. Application of TT increased AQP1immunoreactivity and might have a role in absorption activities in the intestines.

Fasting influences aquaporin expression, water transport and adipocyte metabolism in the peritoneal membrane.

The water channels aquaporin-1 (AQP1) and AQP7 are abundantly expressed in the peritoneal membrane. While AQP1 facilitates water transport during peritoneal dialysis (PD), the role of AQP7, which mediates glycerol transport during fasting, remains unknown. We investigated the distribution of AQP7 and AQP1 and used a mouse model of PD to investigate the role of AQP7 in the peritoneal membrane at baseline and after fasting. Single nucleus RNA-sequencing revealed that AQP7 was mostly detected in mature adipocytes, whereas AQP1 was essentially expressed in endothelial cells. Fasting induced significant decreases in whole body fat, plasma glucose, insulin and triglycerides, as well as higher plasma glycerol and corticosterone levels in mice, paralleled by major decreases in adipocyte size and levels of fatty acid synthase and leptin, and increased levels of hormone-sensitive lipase mRNAs in the peritoneum. Mechanistically, fasting upregulated the expression of AQP1 and AQP7 in the peritoneum, with increased ultrafiltration but no change in small solute transport. Studies based on Aqp1 and Aqp7 knockout mice and RU-486 inhibition demonstrated that the glucocorticoid induction of AQP1 mediates the increase in ultrafiltration whereas AQP7 regulates the size of adipocytes in the peritoneum. Fasting induces a coordinated regulation of lipolytic and lipogenic factors and aqua(glycero)porins in the peritoneum, driving structural and functional changes. These data yield novel information on the specific roles of aquaporins in the peritoneal membrane and indicate that fasting improves fluid removal in a mouse model of PD.