Aquaporin-4 Protein Research Articles

Dynamics of Salivary Gland AQP5 under Normal and Pathologic Conditions.

Aquaporin 5 (AQP5) plays an important role in the salivary gland function. The mRNA and protein for AQP5 are expressed in the acini from embryonic days E13-16 and E17-18, respectively and for entire postnatal days. Ligation-reopening of main excretory duct induces changes in the AQP5 level which would give an insight for mechanism of regeneration/self-duplication of acinar cells. The AQP5 level in the submandibular gland (SMG) decreases by chorda tympani denervation (CTD) via activation autophagosome, suggesting that its level in the SMG under normal condition is maintained by parasympathetic nerve. Isoproterenol (IPR), a β-adrenergic agonist, raised the levels of membrane AQP5 protein and its mRNA in the parotid gland (PG), suggesting coupling of the AQP5 dynamic and amylase secretion-restoration cycle. In the PG, lipopolysaccharide (LPS) is shown to activate mitogen-activated protein kinase (MAPK) and nuclear factor-kappa B (NF-κB) signalings and potentially downregulate AQP5 expression via cross coupling of activator protein-1 (AP-1) and NF-κB. In most species, Ser-156 and Thr-259 of AQP5 are experimentally phosphorylated, which is enhanced by cAMP analogues and forskolin. cAMP-dependent phosphorylation of AQP5 does not seem to be markedly involved in regulation of its intracellular trafficking but seems to play a role in its constitutive expression and lateral diffusion in the cell membrane. Additionally, Ser-156 phosphorylation may be important for cancer development.

Uncoupling of the Astrocyte Syncytium Differentially Affects AQP4 Isoforms.

The water channel protein aquaporin-4 (AQP4) and the gap junction forming proteins connexin-43 (Cx43) and connexin-30 (Cx30) are astrocytic proteins critically involved in brain water and ion homeostasis. While AQP4 is mainly involved in water flux across the astrocytic endfeet membranes, astrocytic gap junctions provide syncytial coupling allowing intercellular exchange of water, ions, and other molecules. We have previously shown that mice with targeted deletion of Aqp4 display enhanced gap junctional coupling between astrocytes. Here, we investigate whether uncoupling of the astrocytic syncytium by deletion of the astrocytic connexins Cx43 and Cx30 affects AQP4 membrane localization and expression. By using quantitative immunogold cytochemistry, we show that deletion of astrocytic connexins leads to a substantial reduction of perivascular AQP4, concomitant with a down-regulation of total AQP4 protein and mRNA. Isoform expression analysis shows that while the level of the predominant AQP4 M23 isoform is reduced in Cx43/Cx30 double deficient hippocampal astrocytes, the levels of M1, and the alternative translation AQP4ex isoform protein levels are increased. These findings reveal a complex interdependence between AQP4 and connexins, which are both significantly involved in homeostatic functions and astrogliopathologies.

Interactive effects of iron and light limitation on the molecular physiology of the Southern Ocean diatom Fragilariopsis kerguelensis

AbstractThe polar diatom Fragilariopsis kerguelensis is ubiquitous in Southern Ocean waters and is a major responder to iron fertilization, encountering large gradients in iron concentrations and light availability. We performed a comparative transcriptomic analysis of F. kerguelensis grown under varying iron and light conditions in order to investigate the molecular underpinnings that may explain its physiological response to iron and light limitation. Low iron reduced growth rates more than low light, but there was not an additive effect of low iron and low light on growth rate. Low iron treatments (saturating and low light) had the largest transcriptomic response; however, expression patterns were more similar in low light treatments (high and low iron). Under iron and light limitation, carbon fixation and amino acid, ribosome, and sulfur metabolisms were overrepresented relative to the control (iron replete, saturating light). Transcripts of genes encoding for the proteins aquaporin, proteorhodopsin, plastocyanin, and flavodoxin were overrepresented to the greatest extent in the low iron/low light treatment, indicating there may be an additive effect of iron/light colimitation at the molecular level. Iron and light replete cells demonstrated increased expression of genes encoding for the proteins ferritin, carbonic anhydrase, and numerous iron‐dependent proteins relative to the growth‐limiting treatments. This transcriptome analysis reveals mechanisms that may underpin the ecological success of this diatom in low iron and light environments, highlighting the important role of diversified photosynthetic isoforms, iron acquisition, unique detoxification mechanisms of reactive oxygen species, and metabolic shifts in amino acid recycling and carbon metabolism.

Abstract TP115: Nrf2 Plays an Essential Role in Long-Term Neuroprotection of Ginseng in Permanent Cerebral Ischemia

Introduction: Cerebral ischemia is a devastating disease with a high incidence of death and disability; however, effective therapeutics remain limited. The transcriptional factor Nrf2 has been shown to play a pivotal role in the endogenous defense against brain oxidative stress and inflammation; therefore, it represents a promising target for stroke intervention. The natural potential Nrf2-inducer ginseng, extracted from the root of Panax ginseng C.A.Meyer, has been widely used in East Asia for thousands of years, exhibiting potent anti-inflammatory and antioxidative properties. However, the long-term effects of Nrf2 and the standardized Korean red ginseng extract (ginseng) on permanent cerebral ischemic damage have not yet been reported. Methods: Wildtype (WT) and Nrf2 –/– adult mice were treated with either vehicle (water) or ginseng for 7 days and subjected to the permanent distal middle cerebral artery occlusion (pdMCAO). The infarct volume, the reactive astrogliosis and microgliosis, and water regulatory protein aquaporin 4 (AQP4) were examined 28 days after the initiation of stroke. Data acquisition and analyses were performed by an observer blinded to the treatment. Results: When compared with the WT matched controls, the Nrf2 disruption significantly enlarged the infarct volume by 40.4±10.1% (n=7 per group; p<0.05), increased levels of reactive gliosis and AQP4 protein after pdMCAO. Interestingly, ginseng significantly reduced the infarct volume and attenuated the reactive gliosis and AQP4 in the ischemic WT mice (47.3±6.9%, n=12; p<0.01), but not in the Nrf2 -/- mice (25.5±5.6%, n=11; p=0.241). Conclusion: Nrf2 plays an important role in the long-term recovery of permanent cerebral ischemic damage and neuroprotection of ginseng.

Abstract WP160: Conivaptan (Combined Vasopressin Receptor Antagonism) Attenuates Cerebral Edema Following Ischemic Stroke in Rodent Model

Objective: To study the potential role of Conivaptan on cerebral edema, infarct volume, neurological deficit and survival. Introduction: Although vasopressin has a significant detrimental role in stroke-related cerebral edema, the effect of mixed vasopressin antagonism in stroke has not been well studied. We studied the effects of conivaptan on the course of cerebral edema, severity of neurological deficit, infarct volume, aquaporin-4 (AQP4) protein levels and survival after experimental stroke. Methods: Animals were randomized to receive either conivaptan or vehicle after reperfusion of experimental middle cerebral artery occlusion. The severity of neurological deficit, edema, and infarct volume assessments were performed by an investigator blinded to group assignment. All assessments were performed at either 12h or 24h and Western blot was subsequently used to investigate AQP4 levels. Results: At 12h, conivaptan-treated mice (n=16) had 6.64±6.50% ipsilateral hemispheric enlargement compared to 16.55±7.05% in control mice (n=16, p=0.0003). Similarly, at 24h, conivaptan-treated mice (n=12) had 6.81±4.63% ipsilateral hemispheric enlargement in comparison to 13.93±5.43% in control mice (n=12, p=0.0023). At 24h, the conivaptan-treated mice had lower neurological deficits in comparison to control (p=0.04). There was no significant effect of conivaptan on infarct size or AQP4 levels in comparison to vehicle, naïve and sham group. Conclusions: The present study highlights the role of mixed vasopressin receptor antagonism in reducing cerebral edema secondary to brain ischemia. This data suggests the possibility of developing vasopressin antagonism as a new adjuvant in treatment of stroke-related brain edema.

Abstract TP285: Dimethyl Fumarate Protects Against Hypoxic-Ischemic Brain Damage and Attenuates Reactive Gliosis in an Nrf2-Dependent Manner: Focus on Hippocampal Injury

Introduction: Recently, based on the purported antioxidative and anti-inflammatory properties, dimethyl fumarate (DMF) has exhibited protective potential in various acute and chronic neurological conditions. Its effect on cerebral ischemia and underlying mechanisms remain inconclusive; furthermore, increasing evidence indicates the involvement of the transcriptional factor Nrf2. Hypothesis: DMF plays a beneficial role on hippocampal neuronal loss and reactive gliosis induced by hypoxia-ischemia (HI) through an Nrf2-dependent mechanism. Methods: Adult wildtype (WT) and Nrf2 -/- mice were pretreated with DMF for 7 days prior to HI. Results: At 24h after HI, DMF significantly reduced infarct volume (52.5±12.3%), brain edema (61.5±17.4%), and hippocampal CA1 neuronal degeneration, and induced expressions of Nrf2 target proteins in the WT (p<0.01), but not in the Nrf2 -/- mice. Such hippocampal neuroprotective benefits were also observed at 6h and 7 days after HI. The dynamic attenuation of reactive gliosis in microglia and astrocytes correlated well with this sustained neuroprotection in an Nrf2-dependent manner. In both early and late stages of HI, the astrocytic water transport channel protein aquaporin 4 was also attenuated after HI in WT, but not Nrf2 -/- , mice treated with DMF. Conclusion: Together, DMF confers robust and prolonged Nrf2-dependent neuroprotection against ischemic hippocampal damage. The salutary Nrf2-dependent attenuation of reactive gliosis may contribute to this neuroprotection, offering new insights into the cellular basis of an Nrf2-targeting strategy for stroke prevention and/or treatment. As DMF is already clinically approved for multiple sclerosis, it makes it a unique potential prototypical example of drug repurposing for treatment and/or prevention of stroke damage.

Effects of sinomenine on brain edema and expression of aquaporins in rats with acute brain injury

Objective To investigate the effects of sinomenine on brain edema and the expression of aquaporin 4 (AQP-4) and aquaporin 5 (AQP-5) in rats with acute brain injury. Methods According to random number table method, rats were divided into sham operation group, model group, low-dose sinomenine group, high-dose sinomenine group, 20 in each group. In addition to the sham operation group, the rat brain injury model was established by Feeney free falling impact method. Rats in low and high dose of sinomenine group were given sinomenine 30, 60 mg/kg by intraperitoneal injection, and the sham operation group and model group were injected intraperitoneally with the same volume of normal saline, once per day for 7 days. Histopathological changes in each group were observed by HE staining and electron microscope. Western blot and RT-PCR were used to detect AQP-4 and AQP-5 protein and gene expression in brain tissue. Results The pathological results showed that the nerve cells in the model group were loosely arranged, disordered in hierarchy, some cells appear to have degenerated. The degeneration and necrosis of nerve cells in the low and high dose sinomenine group were less than those in the model group. Compared to the model group, the expression of AQP-4 (0.74 ± 0.13, 0.49 ± 0.11 vs. 1.30 ± 0.21), AQP-5 (0.98 ± 0.07, 0.45 ± 0.10 vs. 1.47 ± 0.18) in the low dose and high dose sinomenine group significantly decreased (P<0.05). The expression of AQP-4 (1.48 ± 0.18, 1.26 ± 0.12 vs. 2.04 ± 0.14), AQP-5 (1.31 ± 0.17, 1.20 ± 0.11 vs. 1.87 ± 0.15) mRNA in the low dose and high dose sinomenine group significantly decreased (P<0.05). Conclusions Sinomenine could alleviate cerebral injury by lowering the expression of AQP-4 and AQP-5. Key words: Sinomenine; Brain injuries; Brain edema; Aquaporin 4; Aquaporin 5; Rats

Investigation of the relationship cellular and physiological degeneration in the mandible with AQP1 and AQP3 membrane proteins

Abstract Objective In this study, we aimed to investigate the changes in the levels of oxidative stress and antioxidant enzymes on the mandibular bone caused by the expression of aquaporin-1 and aquaporin-3 proteins. Material and method 14 Balb/C white mice were divided into two groups of seven, based on whether they are young or old. Mandibular tissue samples were taken for biochemical and histological analysis. Results Findings of our study has shown that, AQP-1 and AQP-3 immunoreactivity significantly decreased in mandibular bone tissues of aged mice in comparison to younger mice (p &lt; 0.05). MDA and AOPP levels, which are the indicators of oxidative stress, increased in elderly mice and antioxidant defense system SOD enzyme activity was decreased (p &lt; 0.05). The TNF-α cytokine level, which is the indicator for inflammations, was found to be higher in older mice than in young mice (p &lt; 0.05). Conclusion As a result, it was observed that cellular damage, disruption in water – electrolyte balance and increased inflammation that occur during the natural process of aging had caused serious and irreversible disturbances.

Localization of aquaporin-3 proteins in the bovine rumen

Urea nitrogen salvaging is a crucial mechanism that ruminants have evolved to conserve nitrogen. Facilitative urea transporter-B proteins are known to be involved in urea transport across the rumen epithelium and thus efficiently facilitate the urea nitrogen salvaging process. Recently, functional studies have suggested that aquaglyceroporin transporters might also play a significant role in ruminal urea transport and aquaporin-3 (AQP3) protein has previously been detected in rumen tissue. In this current study, we investigated the specific localization of AQP3 transporters in the bovine rumen. First, end-point reverse-transcription PCR experiments confirmed strong AQP3 expression in both bovine rumen and kidney. Immunoblotting analysis using 2 separate anti-AQP3 antibodies detected AQP3 protein signals at 25, 32, and 42-45 kDa. Further immunolocalization studies showed AQP3 protein located in all the layers of rumen epithelium, especially in the stratum basale, and in the basolateral membranes of kidney collecting duct cells. These data confirm that AQP3 transporters are highly abundant within the bovine rumen and appear to be located throughout the ruminal epithelial layers. The physiological significance of the multiple AQP3 proteins detected and their location is not yet clear, hence further investigation is required to determine their exact contribution to ruminal urea transport.

Exosomes co-expressing AQP5-targeting miRNAs and IL-4 receptor-binding peptide inhibit the migration of human breast cancer cells.

Aquaporin-5 (AQP5) plays a role in breast cancer cell migration. This study aimed to identify AQP5-targeting miRNAs and examine their effects on breast cancer cell migration through exosome-mediated delivery. Bioinformatic analyses identified miR-1226-3p, miR-19a-3p, and miR-19b-3p as putative regulators of AQP5 mRNA. Immunoblotting revealed a decrease of AQP5 protein abundance when each of these miRNAs was transfected into human breast cancer MDA-MB-231 cells. Quantitative real-time PCR demonstrated the reduction of AQP5 mRNA expression by the transfection of miR-1226-3p and a luciferase reporter assay revealed the reduction of AQP5 translation after the transfection of miR-19b-3p in MDA-MB-231 cells. Consistently, the transfection of each miRNA impeded cell migration. Pathway enrichment analyses showed that these three miRNAs regulate target genes, which were predominantly enriched in the gap junction pathway. For the efficient delivery of AQP5-targeting miRNAs to breast cancer cells, exosomes expressing both miRNAs and a peptide targeting interleukin-4 receptor, which is highly expressed in breast cancer cells, were bioengineered and their inhibitory effects on AQP5 protein expression and cell migration were demonstrated in MDA-MB-231 cells. Taken together, AQP5-regulating miRNAs are identified, which could be exploited for the inhibition of breast cancer cell migration via the exosome-mediated delivery.

Aquaporin 4 knockout increases complete freund's adjuvant-induced spinal central sensitization

Growing evidence suggests a critical role of astrocytes for pain regulation. The water channel protein aquaporin 4 (AQP4), a functional regulator of astrocytes, is involved in various neurological disorders. However, the pathophysiological roles of AQP4 in pain conditions remain unclear. In the present study, we investigated the effect of AQP4 gene knockout in central sensitization induced by complete Freund's adjuvant (CFA). The behavioral analysis revealed that mechanical allodynia and thermal hyperalgesia were more severe in AQP4 null mice than those of wild-type controls over the course of 11 days following CFA intraplantar injection. CFA caused activation of astrocytes with upregulated expression levels of AQP4 and glutamate transporter 1 (GLT1) in the dorsal horn of the spinal cord. AQP4 deficiency reduced GLT1 up-regulation, causing persistent expression of the neuronal activation marker Fos within superficial dorsal horn neurons, including glutamatergic neurons. However, AQP4 deletion did not affect CFA-evoked proinflammatory cytokine expression in the spinal cord. Together, these results have shown that AQP4 absence intensifies CFA-induced spinal central sensitization, which is associated with reduced compensatory up-regulation of GLT1, subsequently increasing glutamatergic overexcitation. Therefore, targeting spinal cord AQP4 may serve as a potential strategy for treatment of peripheral inflammation-evoked hyperalgesia.

Hepatic glycerol metabolism is early reprogrammed in rat liver cancer development

Evidence shows that oral glycerol supplementation during the early stages of rat liver cancer reduces the growth of preneoplastic lesions. Besides, human hepatocellular carcinoma (HCC) cells display decreased expression of glycerol channel aquaporin 9 (AQP9) and also diminished glycerol-3-phosphate (G3P) content. According to this, we analyzed glycerol metabolism during the initial stages of rat liver carcinogenesis. Wistar rats were subjected to a 2-phase model of hepatocarcinogenesis (initiated-promoted, IP group) or left untreated (control, C group). Different features of glycerol metabolism were compared between both groups. IP animals showed increased plasma free glycerol levels and liver AQP9 protein expression. Also, IP rats showed increased glycerol kinase (GK) and glycerol-3-phosphate dehydrogenase (GPDH) hepatic activities. Gluconeogenesis from glycerol both in vivo and in isolated perfused liver was higher in rats having liver preneoplasia. Nevertheless, preneoplastic foci notably reduced AQP9 and GK protein expressions, displaying a reduced ability to import glycerol and to convert it into G3P, as a way to preserve preneoplastic hepatocytes from the deleterious effect of G3P. In conclusion, the metabolic shift that takes place in the initial stages of liver cancer development comprises an increased hepatic utilization of glycerol for gluconeogenesis. Enhanced glucose production from glycerol is mostly carried out by the surrounding non-preneoplastic tissue and can be used as an energy source for the early transformed liver cells.

The Tonoplast Intrinsic Protein Gene KvTIP3 is Responsive to Different Abiotic Stresses in Kosteletzkya virginica.

In higher plants, aquaporin proteins (AQPs) play important roles in the uptake of water across cell membranes. However, their functions in halophytes are still largely unknown. In this work, we isolated, cloned, and identified KvTIP3, a tonoplast intrinsic protein gene from Kosteletzkya virginica. Bioinformatic analyses demonstrated that KvTIP3 encoded a tonoplast protein with the common properties of AQPs. Further multiple sequence alignment and phylogenetic analyses showed that KvTIP3 shared 65%–82% homology with other AQPs from Arabidopsis, cotton, polar, and cocoa. Quantitative real-time PCR (qPCR) analyses revealed that KvTIP3 was ubiquitously expressed in various tissues such as leaves, stems, and roots, with a predominant expression in roots. In addition, KvTIP3 transcript was strongly induced by NaCl, low temperature, and ABA in K. virginica. Our findings suggest that KvTIP3 encodes a new AQP possibly involved in multiple abiotic stress responses in K. virginica, and KvTIP3 could be used as a potential candidate gene for the improvement of plants resistant to various abiotic stresses.

Statins ameliorate cholesterol-induced inflammation and improve AQP2 expression by inhibiting NLRP3 activation in the kidney.

Background: Chronic kidney diseases (CKD) are usually associated with dyslipidemia. Statin therapy has been primarily recommended for the prevention of cardiovascular risk in patients with CKD; however, the effects of statins on kidney disease progression remain controversial. This study aims to investigate the effects of statin treatment on renal handling of water in patients and in animals on a high-fat diet.Methods: Retrospective cohort patient data were reviewed and the protein expression levels of aquaporin-2 (AQP2) and NLRP3 inflammasome adaptor ASC were examined in kidney biopsy specimens. The effects of statins on AQP2 and NLRP3 inflammasome components were examined in nlrp3-/- mice, 5/6 nephroectomized (5/6Nx) rats with a high-fat diet (HFD), and in vitro.Results: In the retrospective cohort study, serum cholesterol was negatively correlated to eGFR and AQP2 protein expression in the kidney biopsy specimens. Statins exhibited no effect on eGFR but abolished the negative correlation between cholesterol and AQP2 expression. Whilst nlrp3+/+ mice showed an increased urine output and a decreased expression of AQP2 protein after a HFD, which was moderately attenuated in nlrp3 deletion mice with HFD. In 5/6Nx rats on a HFD, atorvastatin markedly decreased the urine output and upregulated the protein expression of AQP2. Cholesterol stimulated the protein expression of NLRP3 inflammasome components ASC, caspase-1 and IL-1β, and decreased AQP2 protein abundance in vitro, which was markedly prevented by statins, likely through the enhancement of ASC speck degradation via autophagy.Conclusion: Serum cholesterol level has a negative correlation with AQP2 protein expression in the kidney biopsy specimens of patients. Statins can ameliorate cholesterol-induced inflammation by promoting the degradation of ASC speck, and improve the expression of aquaporin in the kidneys of animals on a HFD.

Neural crest cells bulldoze through the microenvironment using Aquaporin 1 to stabilize filopodia

Neural crest migration requires cells to move through an environment filled with dense extracellular matrix and mesoderm to reach targets throughout the vertebrate embryo. Here, we use high-resolution microscopy, computational modeling, and in vitro and in vivo cell invasion assays to investigate the function of Aquaporin 1 (AQP-1) signaling. We find that migrating lead cranial neural crest cells express AQP-1 mRNA and protein, implicating a biological role for water channel protein function during invasion. Differential AQP-1 levels affect neural crest cell speed and direction, as well as the length and stability of cell filopodia. Furthermore, AQP-1 enhances matrix metalloprotease activity and colocalizes with phosphorylated focal adhesion kinases. Colocalization of AQP-1 with EphB guidance receptors in the same migrating neural crest cells has novel implications for the concept of guided bulldozing by lead cells during migration.

Urinary Concentration Defect and Renal Glycosuria in Cyclosporine-treated Rats.

BackgroundUrinary concentration impairment is a major feature of cyclosporine nephrotoxicity.MethodsWe explored two possible mechanisms that may underlie cyclosporine-induced polyuria; water, and/or osmotic diuresis. Cyclosporine was subcutaneously injected to normal salt-fed Sprague-Dawley rats at a daily dose of 25mg/kg for 2 weeks (Experiment I) and 7.5mg/kg for 6 weeks (Experiment II).ResultsIn Experiment I, cyclosporine treatment caused an increase in urine volume (2.7±0.5 vs. 10.3±1.13mL/d/100 g BW, p<0.001) and a decrease in urine osmolality (2,831±554 vs. 1,379±478mOsm/kg H2O, p<0.05). Aquaporin-2 (AQP2) protein expression decreased in cyclosporine-treated rat kidneys (cortex, 78±8%, p<0.05; medulla, 80±1%, p<0.05). Experiment II also showed that urine volume was increased by cyclosporine treatment (4.97±0.66 vs. 9.65±1.76mL/d/100 g BW, p<0.05). Whereas urine osmolality was not affected, urinary excretion of osmoles was increased (7.5±0.4 vs. 14.9±1.4mosmoles/d/100 g BW, p<0.005). Notably, urinary excretion of glucose increased in cyclosporine-treated rats (7±1 vs. 10,932±2,462 mg/d/100 g BW, p<0.005) without a significant elevation in plasma glucose. In both Experiment I and II, GLUT2 protein expression in the renal cortex was decreased by cyclosporine treatment (Experiment I, 55±6%, p<0.005; Experiment II, 88±3%, p<0.05).ConclusionBoth water diuresis and osmotic diuresis are induced by cyclosporine nephrotoxicity. AQP2 and GLUT2 downregulation may underlie water and osmotic diuresis, respectively.

Calcium sensing receptor exerts a negative regulatory action toward vasopressin-induced aquaporin-2 expression and trafficking in renal collecting duct.

Vasopressin (AVP) plays a major role in the regulation of water homeostasis by its antidiuretic action on the kidney, mediated by V2 receptors. An increase in plasma sodium concentration stimulates AVP release, which in turn promotes water reabsorption. Upon binding to the V2 receptors in the renal collecting duct, AVP induces the expression and apical membrane insertion of the aquaporin-2 (AQP2) water channels and subsequent water reabsorption. AVP regulates two independent mechanisms: the short-term regulation of AQP2 trafficking and long-term regulation of the total abundance of the AQP2 protein in the cells. On the other hand, several hormones, acting through specific receptors, have been reported to antagonize AVP-mediated water transport in kidney. In this respect, we previously described that high luminal Ca2+ in the renal collecting duct attenuates short-term AVP-induced AQP2 trafficking through activation of the Ca2+-sensing receptor (CaSR). This effect is due to reduction of AVP-dependent cAMP generation and possibly hydrolysis. Moreover, CaSR signaling reduces AQP2 abundance both via AQP2-targeting miRNA-137 and the proteasomal degradation pathway. This chapter summarizes recent data elucidating the molecular mechanisms underlying the physiological role of the CaSR-dependent regulation of AQP2 expression and trafficking.

Nanobiotechnology Model Arising from Coronavirus Interacting with the AQP Channels Along the Respiratory Regions and Estimating the Infectivity Rate of the COVID19 Outbreak Based on Temperature and Direct Contact Rate

Coronavirus (COVID19) is an infectious disease that attacks the human body, particularly within the respiratory regions, e.g., nasal and lung tissues. COVID19 infection is classified into three different stages: mild, moderate, and severe. Recovery from the first two stages can mostly be achieved without special treatment, but these stages can lead to death for older people and those who have underlying medical conditions, such as diabetes, chronic-respiratory disease, HIV, and cardiovascular disease. COVID19 prefers to attack the tissues and membranes of the respiratory system, especially those found in the nose, throat, and on the external surface of the lungs. Aquaporins (AQPs) are a large family of integral biomembranes that facilitate transport of water and small biomolecules between cells. The current work develops two scientific sub-models, i.e., biological and statistical. The biological model is aimed at investigating the realistic mechanism of bio-interaction between the two types of COV and different AQP protein channels. This model is obtained mathematically by evaluating the magnitude of the potential energy arising from SARSCOV and COVID19 penetrating the cavity of the AQP protein channels located on the external surface of human cells. We use an exponential function to estimate the transmission rate of COVID19 with respect to time in different territories. Additionally, we observe that temperature and direct contact play major roles in determining the number of infected cases, and consider relative humidity as a secondary factor. Our results show that AQP1, AQP3, and AQP4 are the most favorable tissues for COVID19 spread because their pH exceeds 6.5. A mathematical model is developed that describes the behavior of the COVID19 outbreak in terms of temperature (μ) and direct contact (α) rate.

Prognostic Role of mRNA-Expression of Aquaporins (AQP) 3, 4, 7 and 9 in Stage pT1 Non-Muscle-Invasive Bladder Cancer.

AQP proteins show a variety of functions in human cell metabolism. The role of different AQP subtypes in tumor metabolism and prognosis are subject of ongoing research. To investigate the mRNA expression of Aquaporin (AQP) 3, 4, 7 and 9 in pT1 non-muscle-invasive bladder cancer (NMIBC) and its prognostic value in therapeutic decision making. Formalin-fixed-paraffin-embedded (FFPE) tissues from transurethral resection of the bladder (TURB) from 112 patients with initial diagnosis of stage pT1 NMIBC were analyzed retrospectively together with clinical data and therapeutic approaches. mRNA expression of AQP3, 4, 7 and 9 was measured and quantified using RT-qPCR. Of the 112 patients (83.9%male, median age 72 years), 40 had a recurrence (35.7%), 16 a progression (14.3%) and 14 patients (12.5%) died tumor-related. mRNA expression for AQP3 was detected in 99.1%, AQP4 in 46.4%, AQP7 in 86.6%and AQP9 in 97.3%. Spearman analysis revealed statistically significant correlations between AQP3, AQP7 and AQP9 mRNA expression with adverse clinical and histopathological parameters (WHO1973 grade 3, concomitant Cis or multifocality). High AQP9 mRNA expression was associated with worse PFS in the total cohort (p = 0.034) and in Grade 3 tumors (p = 0.003) in Kaplan-Meier analysis. In patients with bladder sparing approach, high AQP3 mRNA expression was significantly associated with worse CSS in patients receiving BCG therapy (p = 0.029). mRNA expression of AQP3, 7 and 9 correlates with adverse clinical and pathological parameters. AQP3 and 9 may help to identify a subgroup of highest risk patients who may be considered for early cystectomy.

Edaravone Exerts Brain Protective Function by Reducing the Expression of AQP4, APP and Aβ Proteins.

This study aims to investigate the changes of aquaporin-4 (AQP4), β-amyloid precursor proteins (APP) and β-amyloid (Aβ) in brain tissues after cerebral ischemiareperfusion injury (CIRI), and evaluate the effect of edaravone. The Middle Cerebral Artery Occlusion was used to establish CIRI in rats. Rats were divided into control, model and edaravone groups. The neurological deficits in the model group were obvious and the neurological score increased compared to the control group, while the neurological deficits of the edaravone group were improved as the neurological score decreased compared to the model group. The number of pyramidel cells in the hippocampus of the model group was significantly decreased whereas edaravone could reverse this decrease. The model group had significantly higher levels of Aβ, APP and AQP4 than the control group and edaravone group, suggesting that they might be involved in the neuronal cell damage. Meanwhile, the increased AQP4 might enhance the permeability of cells, and thus cause cell damage and neurological deficit. Conclusively, edaravone could reduce brain edema, protect neuronal cells and improve the neurological impairment of rats possibly by decreasing the expression of Aβ, APP and AQP4. Therefore, edaravone may have the potential to treat neurodegenerative diseases (such as Alzheimer's disease).