Altered Cell Clusters and Upregulated Aqp1 in Connexin 50 Knockout Lens Epithelium.

Purpose: To characterize the heterogeneity and cell clusters of postnatal lens epithelial cells (LECs) and to investigate the downstream targets of connexin 50 (Cx50) in the regulation of lens homeostasis and lens growth. To determine differentially expressed genes (DEGs) in the connexin 50 knockout (Cx50KO) lens epithelial cells that shed light on novel mechanism underlying the cataract and small size of the Cx50KO lenses. Methods: Single-cell RNA sequencing (scRNA-seq) of lens epithelial cells isolated from one-month-old Cx50KO and wild-type (WT) mice were performed. Differentially expressed genes were identified, and selected DEGs were further studied by quantitative real-time PCR (RT-qPCR) analysis and Western blot analysis. Results: The expression profiles of several thousand genes were identified by scRNA-seq data analysis. In comparison to the WT control, many DEGs were identified in the Cx50KO lens epithelial cells, including growth regulating transcriptional factors and genes encoding water channels. Significantly upregulated aquaporin 1 (Aqp1) gene expression was confirmed by RT-qPCR, and upregulated AQP1 protein expression was confirmed by Western blot analysis and immunostaining both in vivo and in vitro. Conclusions: Lens epithelial cells exhibit an intrinsic heterogeneity of different cell clusters in regulating lens homeostasis and lens growth. Upregulated Aqp1 in Cx50KO lens epithelial cells suggests that both connexin 50 and AQP1 likely play important roles in regulating water homeostasis in lens epithelial cells.

Aquaporin 1 is renoprotective in septic acute kidney injury by attenuating inflammation, apoptosis and fibrosis through inhibition of P53 expression.

Sepsis associated Acute kidney injury (AKI) is a common clinical syndrome characterized by suddenly decreased in renal function and urinary volume. This study was designed to investigate the role of Aquaporin 1 (AQP1) and P53 in the development of sepsis-induced AKI and their potential regulatory mechanisms. Firstly, transcriptome sequencing analysis of mice kidney showed AQP1 expression was reduced and P53 expression was elevated in Cecal ligation and puncture (CLP)-induced AKI compared with controls. Bioinformatics confirmed that AQP1 expression was remarkably decreased and P53 expression was obviously elevated in renal tissues or peripheral blood of septic AKI patients. Moreover, we found in vivo experiments that AQP1 mRNA levels were dramatically decreased and P53 mRNA significantly increased following the increased expression of inflammation, apoptosis, fibrosis, NGAL and KIM-1 at various periods in septic AKI. Meanwhile, AQP1 and P53 protein levels increased significantly first and then decreased gradually in kidney tissue and serum of rats in different stages of septic AKI. Most importantly, in vivo and vitro experiments demonstrated that silencing of AQP1 greatly exacerbates renal or cellular injury by up-regulating P53 expression promoting inflammatory response, apoptosis and fibrosis. Overexpression of AQP1 prevented the elevation of inflammation, apoptosis and fibrosis by down-regulating P53 expression in Lipopolysaccharide (LPS)-induced AKI or HK-2 cells. Therefore, our results suggested that AQP1 plays a protective role in modulating AKI and can attenuate inflammatory response, apoptosis and fibrosis via downregulating P53 in septic AKI or LPS-induced HK-2cells. The pharmacological targeting of AQP1 mediated P53 expression might be identified as potential targets for the early treatment of septic AKI.

Aquaporin 1 aggravates lipopolysaccharide-induced macrophage polarization and pyroptosis.

Acute respiratory infections (ARIs) are associated with high mortality and morbidity. Acute lung injury (ALI) is caused by the activation of immune cells during ARIs caused by viruses such as SARS-CoV-2. Aquaporin 1 (AQP1) is distributed in a variety of immune cells and is related to the occurrence of ALI, but the mechanism is not clear. A reference map of human single cells was used to identify macrophages in COVID-19 patients at the single-cell level. "FindMarkers" was used to analyze differentially expressed genes (DEGs), and "clusterProfiler" was used to analyze the functions of the DEGs. An M1 macrophage polarization model was established with lipopolysaccharide (LPS) in vitro, and the relationships among AQP1, pyroptosis and M1 polarization were examined by using an AQP1 inhibitor. Transcriptome sequencing and RT-qPCR were used to examine the molecular mechanism by which AQP1 regulates macrophage polarization and pyroptosis. Antigen presentation, M1 polarization, migration and phagocytosis are abnormal in SARS-CoV-2-infected macrophages, which is related to the high expression of AQP1. An M1 polarization model of macrophages was constructed in vitro, and an AQP1 inhibitor was used to examine whether AQP1 could promote M1 polarization and pyroptosis in response to LPS. Transcriptome and cell experiments showed that this effect was related to a decrease in chemokines caused by AQP1 deficiency. AQP1 participates in M1 polarization and pyroptosis in macrophages by increasing the levels of chemokines induced by LPS, which provides new insights for the diagnosis and treatment of ALI.

Aquaporin 1 confers apoptosis resistance in pulmonary arterial smooth muscle cells from the SU5416 hypoxia rat model.

Pulmonary hypertension (PH) arises from increased pulmonary vascular resistance due to contraction and remodeling of the pulmonary arteries. The structural changes include thickening of the smooth muscle layer from increased proliferation and resistance to apoptosis. The mechanisms underlying apoptosis resistance in PH are not fully understood. In cancer cells, high expression of aquaporin 1 (AQP1), a water channel, is associated with apoptosis resistance. We showed AQP1 protein was expressed in pulmonary arterial smooth muscle cells (PASMCs) and upregulated in preclinical PH models. In this study, we used PASMCs isolated from control male rats and the SU5416 plus hypoxia (SuHx) model to test the role of AQP1 in modulating susceptibility to apoptosis. We found the elevated level of AQP1 in PASMCs from SuHx rats was necessary for resistance to apoptosis and that apoptosis resistance could be conferred by increasing AQP1 in control PASMCs. In exploring the downstream pathways involved, we found AQP1 levels influence the expression of Bcl-2, with enhanced AQP1 levels corresponding to increased Bcl-2 expression, reducing the ratio of BAX to Bcl-2, consistent with apoptosis resistance. These results provide a mechanism by which AQP1 can regulate PASMC fate.

CRISPR-CasRx-mediated disruption of Aqp1/Adrb2/Rock1/Rock2 genes reduces intraocular pressure and retinal ganglion cell damage in mice.

Glaucoma affects approximately 80 million individuals worldwide, a condition for which current treatment options are inadequate. The primary risk factor for glaucoma is elevated intraocular pressure. Intraocular pressure is determined by the balance between the secretion and outflow of aqueous humor. Here we show that using the RNA interference tool CasRx based on shH10 adenovirus-associated virus can reduce the expression of the aqueous humor circulation related genes Rock1 and Rock2, as well as aquaporin 1 and ß2 adrenergic receptor in female mice. This significantly reduced intraocular pressure in female mice and provided protection to the retina ganglion cells, ultimately delaying disease progression. In addition, we elucidated the mechanisms by which the knockdown of Rock1 and Rock2, or aquaporin 1 and ß2 adrenergic receptor in female mice, reduces the intraocular pressure and secures the retina ganglion cells by single-cell sequencing.

Aquaporin 2 in Cerebral Edema: Potential Prognostic Marker in Craniocerebral Injuries.

Despite continuous medical advancements, traumatic brain injury (TBI) remains a leading cause of death and disability worldwide. Consequently, there is a pursuit for biomarkers that allow non-invasive monitoring of patients after cranial trauma, potentially improving clinical management and reducing complications and mortality. Aquaporins (AQPs), which are crucial for transmembrane water transport, may be significant in this context. This study included 48 patients, with 27 having acute (aSDH) and 21 having chronic subdural hematoma (cSDH). Blood plasma samples were collected from the participants at three intervals: the first sample before surgery, the second at 15 h, and the third at 30 h post-surgery. Plasma concentrations of AQP1, AQP2, AQP4, and AQP9 were determined using the sandwich ELISA technique. CT scans were performed on all patients pre- and post-surgery. Correlations between variables were examined using Spearman's nonparametric rank correlation coefficient. A strong correlation was found between aquaporin 2 levels and the volume of chronic subdural hematoma and midline shift. However, no significant link was found between aquaporin levels (AQP1, AQP2, AQP4, and AQP9) before and after surgery for acute subdural hematoma, nor for AQP1, AQP4, and AQP9 after surgery for chronic subdural hematoma. In the chronic SDH group, AQP2 plasma concentration negatively correlated with the midline shift measured before surgery (Spearman's ρ -0.54; p = 0.017) and positively with hematoma volume change between baseline and 30 h post-surgery (Spearman's ρ 0.627; p = 0.007). No statistically significant correlation was found between aquaporin plasma levels and hematoma volume for AQP1, AQP2, AQP4, and AQP9 in patients with acute SDH. There is a correlation between chronic subdural hematoma volume, measured radiologically, and serum AQP2 concentration, highlighting aquaporins' potential as clinical biomarkers.

AQP1 Deficiency Drives Phthalate-Induced Epithelial Barrier Disruption through Intestinal Inflammation.

Di-2-ethylhexyl phthalate (DEHP) is frequently used as a plasticizer to enhance the plasticity and durability of agricultural products, which pose adverse effects to human health and the environment. Aquaporin 1 (AQP1) is a main water transport channel protein and is involved in the maintenance of intestinal integrity. However, the impact of DEHP exposure on gut health and its potential mechanisms remain elusive. Here, we determined that DEHP exposure induced a compromised duodenum structure, which was concomitant with mitochondrial structural injury of epithelial cells. Importantly, DEHP exposure caused duodenum inflammatory epithelial cell damage and strong inflammatory response accompanied by activating the TLR4/MyD88/NF-κB signaling pathway. Mechanistically, DEHP exposure directly inhibits the expression of AQP1 and thus leads to an inflammatory response, ultimately disrupting duodenum integrity and barrier function. Collectively, our findings uncover the role of AQP1 in phthalate-induced intestinal disorders, and AQP1 could be a promising therapeutic approach for treating patients with intestinal disorders or inflammatory diseases.

Leptin Promotes Vasculogenic Mimicry in Breast Cancer Cells by Regulating Aquaporin-1.

Leptin is an obesity-related hormone that plays an important role in breast cancer progression. Vasculogenic mimicry (VM) refers to the formation of vascular channels lined by tumor cells. This study aimed to investigate the relationship between leptin and VM in human breast cancer cells. VM was measured by a 3D culture assay. Signal transducers and activators of transcription 3 (STAT3) signaling, aquaporin-1 (AQP1), and the expression of VM-related proteins, including vascular endothelial cadherin (VE-cadherin), twist, matrix metalloproteinase-2 (MMP-2), and laminin subunit 5 gamma-2 (LAMC2), were examined by Western blot. AQP1 mRNA was analyzed by a reverse transcriptase-polymerase chain reaction (RT-PCR). Leptin increased VM and upregulated phospho-STAT3, VE-cadherin, twist, MMP-2, and LAMC2. These effects were inhibited by the leptin receptor-blocking peptide, Ob-R BP, and the STAT3 inhibitor, AG490. A positive correlation between leptin and AQP1 mRNA was observed and was confirmed by RT-PCR. Leptin upregulated AQP1 expression, which was blocked by Ob-R BP and AG490. AQP1 overexpression increased VM and the expression of VM-related proteins. AQP1 silencing inhibited leptin-induced VM and the expression of VM-related proteins. Thus, these results showed that leptin facilitates VM in breast cancer cells via the Ob-R/STAT3 pathway and that AQP1 is a key mediator in leptin-induced VM.

A Dual-Gene Reporter-Amplifier Architecture for Enhancing the Sensitivity of Molecular MRI by Water Exchange.

The development of genetic reporters for magnetic resonance imaging (MRI) is essential for investigating biological functions in vivo. However, current MRI reporters have low sensitivity, making it challenging to create significant contrast against the tissue background, especially when only a small fraction of cells express the reporter. To overcome this limitation, we developed an approach for amplifying the sensitivity of molecular MRI by combining a chemogenetic contrast mechanism with a biophysical approach to increase water diffusion through the co-expression of a dual-gene construct comprising an organic anion transporting polypeptide, Oatp1b3, and a water channel, Aqp1. We first show that the expression of Aqp1 amplifies MRI contrast in cultured cells engineered to express Oatp1b3. We demonstrate that the contrast amplification is caused by Aqp1-driven increase in water exchange, which provides the gadolinium ions internalized by Oatp1b3-expressing cells with access to a larger water pool compared with exchange-limited conditions. We further show that our methodology allows cells to be detected using approximately 10-fold lower concentrations of gadolinium than that in the Aqp1-free scenario. Finally, we show that our approach enables the imaging of mixed-cell cultures containing a low fraction of Oatp1b3-labeled cells that are undetectable on the basis of Oatp1b3 expression alone.

Overexpression of aquaporin-1 plays a vital role in proliferation, apoptosis, and pyroptosis of Wilms' tumor cells.

BACKGROUND: Nephroblastoma, also known as Wilms' tumor (WT), is an embryonic malignant tumor and one of the most common malignant tumors in the abdominal region of children. The exact role and underlying mechanisms of aquaporin-1 (AQP1) in the occurrence and development of nephroblastoma remain unclear. METHODS: After overexpression of AQP1, cell proliferation was assessed using the CCK-8 proliferation assay and EdU staining. Flow cytometry was employed to assess cell apoptosis, and Western blotting (WB) analysis was conducted to validate the expression of relevant protein markers. mRNA sequencing (mRNA-Seq) was performed on WT cells overexpressing AQP1 to predict and characterize the associated mechanisms. Transmission electron microscopy was utilized to observe changes in the ultrastructure of WT cells undergoing apoptosis and pyroptosis following AQP1 overexpression. Functional in vivo validation was conducted through animal experiments. RESULTS: We validated that overexpression of AQP1 inhibited cell proliferation and promoted cell apoptosis and pyroptosis both in vitro and in vivo. mRNA-Seq analysis of WT cells with AQP1 overexpression suggested that these effects might be mediated through the inhibition of the JAK-STAT signaling pathway. Additionally, we discovered that overexpression of AQP1 activated the classical pyroptosis signaling pathway dependent on caspase-1, thereby promoting pyroptosis in WT. CONCLUSION: These findings highlight the important functional role of AQP1 in the pathobiology of nephroblastoma, providing novel insights into the development of this disease. Moreover, these results offer new perspectives on the potential therapeutic targeting of AQP1 as a treatment strategy for nephroblastoma.

The Expression and Role of Aquaporin 4 in Colon Cancer.

BACKGROUND/AIM: Aquaporins (AQPs) were initially discovered as water channel proteins that facilitate transcellular water movements. Recent studies have shown that AQPs are expressed and play an oncogenic role in various cancers. However, the expression and role of Aquaporin 4 (AQP4) in colon cancer have not been investigated. This study aimed to examine the clinical and pathophysiologic significance of AQP4 in colon cancer. PATIENTS AND METHODS: Immunohistochemistry (IHC) of AQP4 for 145 primary tumor samples obtained from patients with stage II or III colon cancer was performed, and the relationship between AQP4 expression and patients' prognoses was analyzed. Knockdown experiments with AQP4 small interfering RNA using human colon cancer cells were conducted to analyze the effects on cell invasiveness. RESULTS: IHC revealed that AQP4 was scarcely expressed in the noncancerous colonic mucosa. Of the 145 patients who enrolled in this study, 109 (75.2%) and 36 (24.8%) patients were classified as negative and positive for AQP4 expression, respectively. A high level of AQP4 expression is significantly associated with deeper tumors with lymph node metastasis and venous invasion. A 5-year progression-free survival rate of AQP4-positive patients was significantly worse than that of AQP-4 negative patients (70.7% vs. 87.0%, p=0.049). Furthermore, AQP4 knockdown significantly inhibited cell migration and invasion in HCT116 cells. CONCLUSION: AQP4 may be a novel biomarker and therapeutic target for colon cancer.

Molecular basis for human aquaporin inhibition.

Cancer invasion and metastasis are known to be potentiated by the expression of aquaporins (AQPs). Likewise, the expression levels of AQPs have been shown to be prognostic for survival in patients and have a role in tumor growth, edema, angiogenesis, and tumor cell migration. Thus, AQPs are key players in cancer biology and potential targets for drug development. Here, we present the single-particle cryo-EM structure of human AQP7 at 3.2-Å resolution in complex with the specific inhibitor compound Z433927330. The structure in combination with MD simulations shows that the inhibitor binds to the endofacial side of AQP7. In addition, cancer cells treated with Z433927330 show reduced proliferation. The data presented here serve as a framework for the development of AQP inhibitors.

Anethole mitigates H2 O2 -induced inflammation in HIG-82 synoviocytes by suppressing the aquaporin 1 expression and activating the protein kinase A pathway.

Rheumatoid arthritis (RA) is an autoimmune inflammatory disease affecting approximately 1% of the global population, with a higher prevalence in women than in men. Chronic inflammation and oxidative stress play pivotal roles in the pathogenesis of RA. Anethole, a prominent compound derived from fennel (Foeniculum vulgare), possesses a spectrum of therapeutic properties, including anti-arthritic, anti-inflammatory, antioxidant, and tumor-suppressive effects. However, its specific impact on RA remains underexplored. This study sought to uncover the potential therapeutic value of anethole in treating RA by employing an H2 O2 -induced inflammation model with HIG-82 synovial cells. Our results demonstrated that exposure to H2 O2 induced the inflammation and apoptosis in these cells. Remarkably, anethole treatment effectively countered these inflammatory and apoptotic processes triggered by H2 O2 . Moreover, we identified the aquaporin 1 (AQP1) and protein kinase A (PKA) pathway as critical regulators of inflammation and apoptosis. H2 O2 stimulation led to an increase in the AQP1 expression and a decrease in p-PKA-C, contributing to cartilage degradation. Conversely, anethole not only downregulated the AQP1 expression but also activated the PKA pathway, effectively suppressing cell inflammation and apoptosis. Furthermore, anethole also inhibited the enzymes responsible for cartilage degradation. In summary, our findings highlight the potential of anethole as a therapeutic agent for mitigating H2 O2 -induced inflammation and apoptosis in synovial cells, offering promising prospects for future RA treatments.

Blood-nerve barrier enhances chronic postsurgical pain via the HIF-1α/ aquaporin-1 signaling axis.

BACKGROUND: Blood nerve barrier (BNB) participates in the development of neuropathic pain. AQP1 is involved in peripheral pain perception and is negatively correlated with HIF-1α phenotype, which regulates endothelial permeability. However, the role of HIF-1α-AQP1-mediated BNB dysfunction in Chronic Postsurgical Pain (CPSP) has not been reported. METHODS: Male Sprague-Dawley rats were randomized into 5 groups: (i) Naive group; (ii) Sham group; (iii) SMIR group: skin/muscle incision and retraction for one hour. Behavioral tests were performed for the three groups, BNB vascular permeability and western blotting were conducted to determine HIF-1α and AQP1 protein expression. (iv) The SMIR + HIF-1α inhibitor group; (v) SMIR + DMSO group. Rats in the two groups were administered with HIF-1α inhibitor (2ME2) or DMSO intraperitoneally on the third day post-SMIR surgery followed by performance of behavioral tests, BNB permeability assessment, and determination of HIF-1α, AQP1 and NF200 protein levels. RESULTS: The permeability of BNB was significantly increased and the expression of AQP1 was downregulated on the 3rd and 7th days post-operation. AQP1 is mainly located in neurons and NF200, CGRP-positive nerve fibers. HIF-1α was highly expressed on the third day post-operation. HIF-1α inhibitor reversed the decrease in AQP1 expression and increase in NF200 expression, barrier permeability and hyperalgesia induced by SMIR on the 3rd day post-surgery. CONCLUSIONS: Early dysfunction of BNB mediated by HIF-1α/AQP1 activated by SMIR may be an important mechanism to promote acute postoperative painful transformation of CPSP. Preadaptive protection of endothelial cells around nerve substructures may be an important countermeasure to inhibit CPSP transformation. Early impairment of BNB function mediated by HIF-1α/AQP1 activated by SMIR may be an important mechanism for promoting acute postoperative pain transformation of CPSP.

Identification of key genes and validation of key gene aquaporin 1 on Wilms' tumor metastasis.

Background: Wilms' tumor (WT) is one of the most common solid tumors in children with unsatisfactory prognosis, but few molecular prognostic markers have been discovered for it. Many genes are associated with the occurrence and prognosis of WT. This study aimed to explore the key genes and potential molecular mechanisms through bioinformatics and to verify the effects of aquaporin 1 (AQP1) on WT metastasis. Methods: Differentially expressed genes (DEGs) were generated from WT gene expression data sets from the Gene Expression Omnibus (GEO) database. Gene functional enrichment analysis was carried out with the Database for Annotation, Visualization and Integrated Discovery (DAVID). A protein-protein interaction network (PPI) was constructed and visualized by the Search Tool for the Retrieval of Interacting Genes/Proteins (STRING) database and Cytoscape software. Minimal Common Oncology Data Elements (MCODE) was used to detect the important modules in the PPI network, and the important nodes (genes) in the PPI module were sorted by CytoHubba. RT-qPCR was performed to validate the expression of the key genes in WT. Wound healing and Transwell assays were used to detect the cell migration and invasion abilities of AQP1-overexpressing cells. Phalloidin-iFlour 488 was used to stain the cytoskeleton to observe how AQP1 overexpression affects cytoskeletal microfilament structure. Results: A total of 73 co-expressed DEGs were chosen for further investigation. The importance of homeostasis and transmembrane transport of ions and water were highlighted by functional analysis. Gene regulatory network and PPI network were predicted. MCODE plug identified two important modules. Finally, top five key genes were identified using CytoHubba, including Renin (REN), nephrosis 2 (NPHS2), Solute Carrier Family 12 Member 3 (SLC12A3), Solute Carrier Family 12 Member 1 (SLC12A1) and AQP1. The five key genes were mainly enriched in cell volume and ion homeostasis. RT-qPCR confirmed the expression of the five key genes in WT. AQP1 was validated to be expressed at significantly lower levels in WT than in normal tissue. AQP1 overexpression significantly reduced the migratory and invasive capacity of Wit-49 cells, as evidenced by reducing the scratch healing rate and the number of perforated control cells by Wit-49 cells. AQP1 overexpression also reduced the expression of biomarkers of epithelial-mesenchymal transformation, decreased levels of vimentin and N-cadherin and increased expression of E-cadherin, resulting in decreased formation of conspicuous lamellipodial protrusions, characteristic of diminished WT cell invasion and migration. Conclusion: Our study reveals the key genes of WT. These key genes may provide novel insight for the mechanism and diagnosis of WT. AQP1 overexpression inhibited invasion, migration, EMT, and cytoskeletal rearrangement of WT cells, indicating that AQP1 plays a role in the pathogenesis of WT.

Endotoxin induced acute kidney injury modulates expression of AQP1, P53 and P21 in rat kidney, heart, lung and small intestine.

This study was designed to explore whether aquaporin 1(AQP1), P53 and P21 can be used as diagnostic biomarkers of lipopolysaccharide (LPS)-induced acute kidney injury (AKI) and potential indicators of sepsis-induced multiple organ injury. Bioinformatics results demonstrated that AQP1, P53, P21 was dramatically elevated 6h after Cecal ligation and puncture (CLP)-AKI in rat renal tissue. The expression of AQP1, P53, P21, NGAL and KIM-1 in kidney were increased significantly at first and then decreased gradually in LPS-induced AKI rats. Histopathological sections showed swelling of tubular epithelial cells and destruction of basic structures as well as infiltration of numerous inflammatory cells in LPS-induced AKI. Moreover, the expressions of AQP1, P53 and P21 in heart were significantly increased in LPS treatment rats, while the AQP1 expressions in lung and small intestine were significantly decreased. The level of NGAL mRNA in heart, lung and small intestine was firstly increased and then decreased during LPS treatment rats, but the expression of KIM-1 mRNA was not affected. Therefore, our results suggest that AQP1, P53 and P21 is remarkably upregulated in LPS-induced AKI, which may be considered as a potential novel diagnostic biomarker of Septic AKI. NGAL may serve as a biomarker of sepsis-induced multiple organ damage during the process of LPS-induced AKI.

The Role of Aquaporin 1 in Water Retention Mechanism of Arachnoid Cysts: Insights from 3 Case Reports.

BACKGROUND Although arachnoid cysts are common lesions, the pathogenesis of their continuous growth remains unclear. We aimed to identify the role of aquaporins in arachnoid cyst specimens. CASE REPORT We selected 3 cases from our own facility and examined arachnoid cyst wall specimens, which were sampled intraoperatively. Patients presented with variable symptoms, a 52-year-old man with a "heavy sensation" in the head and dysesthesia on the left hand, a 68-year-old man with unsteady gait, and finally a 26-year-old woman with a history of intermittent headaches for 10 years. Intraoperative specimens were obtained and examined. Evaluation techniques were light microscopy, immunohistochemical staining for aquaporin, and electron microscopy. Light microscopy showed that cells were arranged in epithelium-like structures forming several thick lamellae, with visible connective tissue among them. Under electron microscopic examination, cells with many or few cell organelles and with spindle-like nuclei were arranged in lamellar or flattened structures. Many vacuolizations were seen in between. Interdigitation of cells and many desmosomes were observed. All 3 cases were positive for aquaporin 1. CONCLUSIONS Our study showed that water transportation through aquaporin 1 has a potential role in the formation and expansion of arachnoid cysts.

Aquaporin 1 Facilitates Ferroptosis, M1 Polarization, Mitochondrial Dysfunction, and Autophagy Damage on Lipopolysaccharide-Induced Macrophage Through Down-Regulation of P53 Signaling Pathway.

This study was designed to investigate the role of aquaporin 1 (AQP1) in ferroptosis, macrophage polarization, mitochondrial dysfunction, and impaired autophagy of lipopolysaccharide (LPS)-stimulated RAW264.7 cells and explored the underlying mechanisms. Si-AQP1-mediated AQP1 silencing RAW264.7 cells was constructed. Si-P53-mediated P53 silencing or pcDNA-P53 overexpression RAW264.7 cells was constructed. Assays of ATP, reverse transcription-quantitative polymerase chain reaction (RT-qPCR), and Mitochondrial membrane potential (JC-1) staining were performed to evaluate mitochondrial biological function. Assays of flow cytometry, reactive oxygen species (ROS) staining, western blot (WB), RT-qPCR, malondialdehyde (MDA), glutathione (GSH), and total superoxide dismutase (SOD) were performed to detect cell ferroptosis, macrophage polarization, and impaired autophagy. The involvement of the P53 pathway was revealed by WB. The results showed that LPS (30 µg/mL) could induce ferroptosis, M1 polarization, mitochondrial dysfunction, and autophagy damage in RAW264.7 cells. Meanwhile, the expression of AQP1 was increased and the expression of P53 was decreased. In addition, Pifithrin-α (PIF; 15 µM), a P53 inhibitor, significantly aggravated ferroptosis, M1 polarization, mitochondrial dysfunction, and autophagy damage as well as up-regulation of AQP1 protein expression in LPS-induced RAW264.7 cells. Interestingly, this phenomenon was markedly alleviated by Kevetrin hydrochloride (70 µM), a P53 agonist. Mechanistically, silencing AQP1 significantly alleviated ferroptosis, M1 polarization, mitochondrial dysfunction, and autophagy damage by up-regulating the expression of P53 in LPS-stimulated RAW264.7 cells. Indeed, inhibition of P53 expression by PIF treatment dramatically reversed this effect on the basis of LPS+si-AQP1. Therefore, we concluded for the first time that AQP1 can promote ferroptosis, M1 polarization, mitochondrial dysfunction, and autophagy impairment by inhibiting the expression of P53 in LPS-stimulated RAW264.7 cells, and AQP1 or P53 may be considered as a crucial determiner that can regulate the biological behavior of RAW264.7 cells stimulated by LPS.