Search Results (81)

Corneal problems, such as delayed and incomplete wound repair, are frequent in diabetes, affecting up to 70% of diabetic patients. In skin, histone deacetylases (HDACs) have been previously found to repress expression of the glycerol channel aquaporin-3 (AQP3), the deficiency of which delays corneal wound healing. We hypothesized that the pan-HDAC inhibitor suberoylanilide hydroxamic acid (SAHA) would improve corneal healing in diabetic mice. Diabetic and normoglycemic C57BL/6J male and female mice were subjected to corneal debridement. Wounds were treated topically with vehicle or SAHA every four hours until they healed. Treatment with SAHA improved wound healing in both normoglycemic and hyperglycemic male mice but, unexpectedly, no changes were detected in female mice. In male mice interleukin-1beta (IL-1β) and tumor necrosis factor (TNF) were significantly increased in diabetic corneas, and SAHA reduced their expression, returning IL-1β and TNF to levels comparable to those in normoglycemic mice regardless of treatment. In normoglycemic male mice, AQP3 levels were not changed in the cornea with SAHA treatment but the expression of AQP3 was increased in the wound’s edge relative to the rest of the cornea. In vitro SAHA treatment of human corneal epithelial cells (HCECs) significantly increased protein expression of AQP3, important for corneal wound healing, but had no effect on ROS production. In conclusion, treatment with SAHA improved corneal wound healing, not only in male mice with diabetes and delayed wound healing but also in normoglycemic male mice; therefore, SAHA could potentially be repurposed as a topical treatment clinically to improve corneal wound healing. Full article

This study investigated how exogenous 2,4-epibrassinolide (EBR) and nitric oxide (NO) enhance the tolerance of cucumber (Cucumis sativus L.) seedlings to NaHCO₃-induced alkaline stress under hydroponic conditions. NaHCO₃ exposure caused severe sodium toxicity, reactive oxygen species (ROS) accumulation, and photosynthetic inhibition, which, together, suppressed plant growth. Treatments with either EBR or NO significantly improved plant performance by alleviating these adverse effects. Both regulators enhanced the ROS scavenging system, maintained ionic homeostasis, and alleviated sodium toxicity. They also stimulated the activities of vacuolar H⁺-ATPase, H⁺-PPase, and plasma membrane H⁺-ATPase, and increased the accumulation of citric and malic acids, thereby sustaining higher photosynthetic efficiency under stress conditions. qRT-PCR analysis further revealed that EBR and NO upregulated SOS1 and NHX2 (sodium transporters) as well as PIP1;2 and PIP2;4 (aquaporins), confirming their involvement in ionic and osmotic regulation. Pharmacological experiments showed that application of NO synthesis inhibitors, including tungstate and L-NAME, as well as the NO scavenger cPTIO, markedly weakened the protective effects of EBR. In contrast, application of the brassinosteroid biosynthesis inhibitor brassinazole (BRz) only had a limited effect on NO-mediated stress tolerance. Collectively, these findings demonstrate that NO functions as a downstream signaling mediator of EBR, coordinating multiple defense pathways including photosynthetic regulation, antioxidant protection, ion balance, aquaporin activity, and organic acid metabolism to enhance cucumber resistance to alkaline stress. Full article

Background: Neuromyelitis optica spectrum disorder (NMOSD) causes severe optic nerve (ON) inflammation and vision loss. Current treatments remain limited, prompting exploration of new therapeutic strategies. This study evaluated the efficacy of ITRI-E-(S)4046 (ITRI-ES), a dual ROCK1/2 and MYLK4 kinase inhibitor, in a rat model of NMOSD optic neuritis. Methods: NMOSD-like optic neuritis was induced in rats by applying NMOSD patient serum-soaked sponges around the ON. Rats received intravitreal injections of either 0.2% ITRI-ES, phosphate-buffered saline (PBS), or intraperitoneal methylprednisolone (MP). Visual function was assessed using flash visual-evoked potentials (fVEP). Retinal ganglion cell (RGC) survival and apoptosis were quantified using FluoroGold retrograde labeling and TUNEL assay. ON inflammation and demyelination were evaluated via immunohistochemistry and Western blot analysis of aquaporin-4 (AQP4), myelin basic protein (MBP), glial fibrillary acidic protein (GFAP), and inflammatory markers. Results: ITRI-ES significantly preserved visual function, restoring fVEP amplitudes (~36 μV vs. ~21 μV in PBS-treated, p < 0.05) and RGC density (~85% of normal vs. ~37% PBS). RGC apoptosis was reduced (~2.3-fold lower vs. PBS, p < 0.05). PBS-treated rats showed decreased AQP4 and MBP (2.5–2.8-fold vs. sham) and increased GFAP (2.8-fold). ITRI-ES maintained higher AQP4 (~3.5-fold) and MBP (~1.5-fold) levels, suppressed GFAP (~5.5-fold vs. PBS), reduced NF-κB, IL-1β, TNF-α, microglia activation, and macrophage infiltration, and increased anti-inflammatory Arg1 and CD206 markers (~3-fold vs. PBS). Conclusions: ITRI-ES alleviates optic nerve inflammation, preserves retinal integrity, and maintains visual function in NMOSD-associated optic neuritis, underscoring kinase inhibition as a promising therapeutic strategy. Full article

Stroke is a leading global cause of mortality and long-term disability, with cerebral edema constituting a major contributor to early neurological deterioration and poor outcomes. Aquaporin-4 (AQP4), the predominant water channel in the central nervous system, plays a paradoxical role in stroke-related brain edema, facilitating both the formation and clearance of excess fluid depending on the pathological context. This review explores the biphasic function of AQP4 across cytotoxic and vasogenic edema, emphasizing its dynamic regulation, subcellular localization, and implications for therapeutic intervention. Evidence from rodent models shows that AQP4 exacerbates cytotoxic edema in acute ischemia by promoting intracellular water influx into astrocytes, whereas in vasogenic edema, it supports fluid reabsorption and glymphatic clearance, thereby alleviating brain swelling. Human studies corroborate AQP4 upregulation in infarcted regions and suggest a potential role for AQP4 polymorphisms and circulating levels as biomarkers of stroke severity and outcome, although larger cohorts and more robust methodological designs are needed. This review also discusses emerging pharmacological strategies to modulate AQP4 activity, including inhibitors, trafficking modulators, and gene-targeted delivery systems, while highlighting challenges in achieving phase-specific modulation. Given its central role in both injury and recovery, AQP4 emerges as a promising yet complex therapeutic target for personalized management of stroke-induced brain edema. Future directions include real-time imaging of AQP4 function, genotype-stratified clinical trials, and integration of AQP4 modulation with current stroke treatment protocols. Full article

Background/Objectives: Cellular oxidative stress is crucial for GV stage oocyte vitrification quality. PI3K and the aquaporin family have been shown to facilitate various cellular processes related to redox homeostasis and energy balance; yet, the mechanisms underlying the involvement of aquaporin 7 (AQP7) in vitrified oocyte oxidative stress remain unclear. The purpose of the present investigation was to evaluate the role of AQP7 in vitrified oocytes and the mechanisms involved. Methods: AQP7 inhibitors were employed to investigate the effect of AQP7 on oxidative stress in mouse-vitrified oocytes, whereas PI3K activators were harnessed to ascertain whether AQP7 serves as a functional molecule involved in this process. Results: Our results indicate that AQP7 inhibition in vitrified oocytes results in a significant decrease in glutathione (GSH) levels associated with cellular oxidation and an elevation in H₂O₂ levels. This was accompanied by exacerbated mitochondrial dysfunction, weakened cytoskeletal proteins, accelerated early apoptosis. Consequently, both survival and maturation rates were markedly reduced. Interestingly, PI3K/AKT activation increased AQP7 expression, restored abnormal mitochondrial distribution, as well as calcium homeostasis, and rescued the oocyte survival/maturation rate. Conclusions: Our results provide new insights indicating that PI3K/AKT/AQP7 decreases oxidative stress by regulating mitochondrial morphology, function, and distribution, thereby rescuing oocyte maturation in vitrification. Full article

This study investigated the potential cosmetic properties of the ethyl acetate (EtOAc) fraction obtained from the roots of Astilboides tabularis (Hemsl.) Engl., focusing on skin-whitening, antiwrinkle, and moisturizing effects using cell-based assays and three-dimensional (3D) artificial skin models (Neoderm-ED and Neoderm-ME). The EtOAc fraction showed significant dose-dependent inhibitory activity against tyrosinase (TYR) (72.0% inhibition at 50 µg/mL), comparable to that of kojic acid. In α-melanocyte-stimulating hormone (α-MSH)-stimulated Neoderm-ME artificial skin containing melanocytes, the EtOAc fraction reduced melanin synthesis at concentrations of 50 and 75 µg/mL and decreased melanogenesis-related gene expression, including TYR, microphthalmia-associated transcription factor (MITF), tyrosinase-related protein-1 (TRP-1) and TRP-2. In the antiwrinkle assays, the EtOAc fraction effectively inhibited elastase activity (41.5% inhibition at 10 µg/mL), exceeding the efficacy of ursolic acid. In the Neoderm-ED artificial skin model, the EtOAc fraction reversed structural damage induced by particulate matter (PM10), restoring epidermal thickness and dermal density. This improvement was supported by the increased expression of skin barrier and antiwrinkle genes, including filaggrin, hyaluronic acid synthase-1 (HAS-1), HAS-2, aquaporin-3 (AQP-3), collagen type I alpha 1 chain (COL1A1), elastin, tissue inhibitor of metalloproteinases-1 (TIMP-1), and TIMP-2, as well as decreased expression of matrix metalloproteinases (MMP-1, MMP-3, and MMP-9). Our results indicate that the EtOAc fraction from A. tabularis root has considerable potential as a multifunctional cosmetic. Full article

Peripheral blood leukocytes are able to migrate to the inflamed tissue, and to engulf and kill invading microbes. This requires rapid modifications of cell morphology and volume through fast movements of osmotic water into or out of the cell. In this process, membrane water channels, aquaporins (AQPs), are critical for cell shape changes as AQP-mediated water movement indirectly affects the cell cytoskeleton and, thereby, the signaling cascades. Recent studies have shown that the deletion or gating of two immune cell AQPs, AQP3 and AQP9, impairs inflammation and improves survival in microbial sepsis. Here, we assessed the expression and distribution of AQP3 and AQP9 in human leukocytes and investigated their involvement in the phagocytosis and killing of the Gram-negative pathogenic bacterium Klebsiella pneumoniae, and their role in lipopolysaccharide (LPS)-induced cell migration. By RT-qPCR, AQP3 mRNA was found in peripheral blood mononuclear cells (PBMCs) but it was undetectable in polymorphonuclear white blood cells (PMNs). AQP9 was found both in PBMCs and PMNs, particularly in neutrophil granulocytes. Immunofluorescence confirmed the AQP3 expression in monocytes and, to a lesser degree, in lymphocytes. AQP9 was expressed both in PBMCs and neutrophils. Specific inhibitors of AQP3 (DFP00173) and AQP9 (HTS13286 and RG100204) were used for bacterial phagocytosis and killing studies. No apparent involvement of individually blocked AQP3 or AQP9 was observed in the phagocytosis of K. pneumoniae by neutrophils or monocytes after 10, 30, or 60 min of bacterial infection. A significant impairment in the phagocytic capacity of monocytes but not neutrophils was observed only when both AQPs were inhibited simultaneously and when the infection lasted for 60 min. No impairment in bacterial clearance was found when AQP3 and AQP9 were individually or simultaneously blocked. PBMC migration was significantly impaired after exposure to the AQP9 blocker RG100204 in the presence or absence of LPS. The AQP3 inhibitor DFP00173 reduced PBMC migration only under LPS exposure. Neutrophil migration was considerably reduced in the presence of RG100204 regardless of whether there was an LPS challenge or not. Taken together, these results indicate critical but distinct involvements for AQP3 and AQP9 in leukocyte motility, while no roles are played in bacterial killing. Further studies are needed in order to understand the precise ways in which these two AQPs intervene during bacterial infections. Full article

Cerebral ischemic stroke is a major cause of death worldwide due to brain cell death resulting from ischemia-reperfusion injury. However, effective treatment approaches for patients with ischemic stroke are still lacking in clinical practice. This study investigated the potential neuroprotective effects of sildenafil, a phosphodiesterase-5 inhibitor, in a gerbil model of global brain ischemia. We investigated the effects of sildenafil on the expression of glial fibrillary acidic protein and aquaporin-4, which are markers related to astrocyte activation and water homeostasis, respectively. Immunofluorescence analysis showed that the number of cells co-expressing these markers, which was elevated in the ischemia-induced group, was significantly reduced in the sildenafil-treated groups. This suggests that sildenafil may have a potential mitigating effect on astrocyte activation induced by ischemia. Additionally, we performed various behavioral tests, including the open-field test, novel object recognition, Barnes maze, Y-maze, and passive avoidance tests, to evaluate sildenafil’s effect on cognitive function impaired by ischemia. Overall, the results suggest that sildenafil may serve as a neuroprotective agent, potentially alleviating delayed neuronal cell death and improving cognitive function impaired by ischemia. Full article

Spermatozoon volume regulation is an essential determinant of male fertility competence in mammals and oviparous fishes. In mammals, aquaporin water channels (AQP3, -7 and -8) have been suggested to play a role in spermatozoon cell volume regulatory responses in the hypotonic female oviduct. In contrast, the ejaculated spermatozoa of marine teleosts, such as the gilthead seabream (Sparus aurata), experience a high hypertonic shock in seawater, initially resulting in an Aqp1aa-mediated water efflux, cell shrinkage and the activation of motility. Further regulatory recovery of cell volume in post-activated spermatozoa is mediated by Aqp4a in cooperation with the Trpv4 Ca²⁺ channel and other ion channels and transporters. Using a paralog-specific antibody, here, we show that seabream spermatozoa also express the aquaglyceroporin AQP3 ortholog Aqp3a, which is highly accumulated in the mid posterior region of the spermatozoon flagella, in a similar pattern to that described in mouse and human sperm. To investigate the role of Aqp3a in seabream sperm motility, we used a recently developed AQP3 antagonist (DFP00173), as well as the seabream Aqp3a-specific antibody (α-SaAqp3a), both of which specifically inhibit Aqp3a-mediated water conductance when the channel was heterologously expressed in Xenopus laevis oocytes. Inhibition with either DFP00173 or α-SaAqp3a did not affect sperm motility activation but did impair the spermatozoon motion kinetics at 30 s post activation in a dose-dependent manner. Interestingly, in close resemblance to the phenotypes of AQP3-deficient murine sperm, electron microscopy image analysis revealed that both Aqp3a inhibitors induce abnormal sperm tail morphologies, including swelling and angulation of the tail, with complete coiling of the flagella in some cases. These findings suggest a conserved role of Aqp3a as an osmosensor that regulates cell volume in fish spermatozoa under a high hypertonic stress, thereby controlling the efflux of water and/or solutes in the post-activated spermatozoon. Full article

To elucidate the possible biological roles of fatty acid-binding protein 5 (FABP5) in the intraocular environment, the cells from which FABP5 originates were determined by using four different intraocular tissue-derived cell types including human non-pigmented ciliary epithelium (HNPCE) cells, retinoblastoma (RB) cells, adult retinal pigment epithelial19 (ARPE19) cells and human ocular choroidal fibroblast (HOCF) cell lines, and the effects of FABP ligand 6, a specific inhibitor for FABP5 and FABP7 were analyzed by RNA sequencing and seahorse cellular metabolic measurements. Among these four different cell types, qPCR analysis showed that FABP5 was most prominently expressed in HNPCE cells, in which no mRNA expression of FABP7 was detected. In RNA sequencing analysis, 166 markedly up-regulated and 198 markedly down-regulated differentially expressed genes (DEGs) were detected between non-treated cells and cells treated with FABP ligand 6. IPA analysis of these DEGs suggested that FABP5 may be involved in essential roles required for cell development, cell survival and cell homeostasis. In support of this possibility, both mitochondrial and glycolytic functions of HNPCE cells, in which mRNA expression of FABP5, but not that of FABP7, was detected, were shown by using a Seahorse XFe96 Bioanalyzer to be dramatically suppressed by FABP ligand 6-induced inhibition of the activity of FABP5. Furthermore, in IPA upstream analysis, various unfolded protein response (UPR)-related factors were identified as upstream and causal network master regulators. Analysis by qPCR analysis showed significant upregulation of the mRNA expression of most of UPR-related factors and aquaporin1 (AQP1). The findings in this study suggest that HNPCE is one of intraocular cells producing FABP5 and may be involved in the maintenance of UPR and AQP1-related functions of HNPCE. Full article

AQPs contribute to breast cancer progression and metastasis. We previously found that genetic inhibition of Aqp7 reduces primary tumor burden and metastasis in breast cancer. In this study, we utilized two AQP inhibitors, Auphen and Z433927330, to evaluate the efficacy of therapeutic inhibition of AQPs in breast cancer treatment. The inhibitors were evaluated in breast cancer for both cytotoxicity and metabolic stability assays across both murine and human breast cancer cell lines. Both AQP inhibitors also affected the expression of other AQP transcripts and proteins, which demonstrates compensatory regulation between AQP family members. As a single agent, Auphen treatment in vivo extended overall survival but did not impact primary or metastatic tumor burden. However, Auphen treatment made cells more responsive to chemotherapy (doxorubicin) or endocrine treatment (tamoxifen, fulvestrant). In fact, treatment with Tamoxifen reduced overall AQP7 protein expression. RNA-seq of breast cancer cells treated with Auphen identified mitochondrial metabolism genes as impacted by Auphen and may contribute to reducing mammary tumor progression, lung metastasis, and increased therapeutic efficacy of endocrine therapy in breast cancer. Interestingly, we found that Auphen and tamoxifen cooperate to reduce breast cancer cell viability, which suggests that Auphen treatment makes the cells more susceptible to Tamoxifen. Together, this study highlights AQPs as therapeutic vulnerabilities of breast cancer metastasis that are promising and should be exploited. However, the pharmacologic results suggest additional chemical refinements and optimization of AQP inhibition are needed to make these AQP inhibitors appropriate to use for therapeutic benefit in overcoming endocrine therapy resistance. Full article

Aquaporins (AQPs) are a family of integral membrane proteins that selectively transport water and glycerol across the cell membrane. Because AQPs are involved in a wide range of physiological functions and pathophysiological conditions, AQP-based therapeutics may have the broad potential for clinical utility, including for disorders of water and energy balance. However, AQP modulators have not yet been developed as suitable candidates for clinical applications. In this study, to identify potential modulators of AQPs, we screened 31 natural products by measuring the water and glycerol permeability of mouse erythrocyte membranes using a stopped-flow light scattering method. None of the tested natural compounds substantially affected the osmotic water permeability. However, several compounds considerably affected the glycerol permeability. Stichoposide C increased the glycerol permeability of mouse erythrocyte membranes, whereas rhizochalin decreased it at nanomolar concentrations. Immunohistochemistry revealed that AQP7 was the main aquaglyceroporin in mouse erythrocyte membranes. We further verified the effects of stichoposide C and rhizochalin on aquaglyceroporins using human AQP3-expressing keratinocyte cells. Stichoposide C, but not stichoposide D, increased AQP3-mediated transepithelial glycerol transport, whereas the peracetyl aglycon of rhizochalin was the most potent inhibitor of glycerol transport among the tested rhizochalin derivatives. Collectively, stichoposide C and the peracetyl aglycon of rhizochalin might function as modulators of AQP3 and AQP7, and suggests the possibility of these natural products as potential drug candidates for aquaglyceroporin modulators. Full article

Triple-negative breast cancer (TNBC) remains one of the most challenging subtypes since it is initially characterized by the absence of specific biomarkers and corresponding targeted therapies. Advances in methodology, translational informatics, genomics, and proteomics have significantly contributed to the identification of therapeutic targets. The development of innovative treatments, such as antibody–drug conjugates and immune checkpoint inhibitors, alongside chemotherapy, has now become the standard of care. However, the quest for biomarkers defining therapy outcomes is still ongoing. Peroxiporins, which comprise a subgroup of aquaporins, which are membrane pores facilitating the transport of water, glycerol, and hydrogen peroxide, have emerged as potential biomarkers for therapy response. Research on peroxiporins reveals their involvement beyond traditional channeling activities, which is also reflected in their cellular localization and roles in cellular signaling pathways. This research on peroxiporins provides fresh insights into the mechanisms of therapy resistance in tumors, offering potential avenues for predicting treatment outcomes and tailoring successful TNBC therapies. Full article

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. Full article

Erythritol has shown excellent insecticidal performance against a wide range of insect species, but the molecular mechanism by which it causes insect mortality and sterility is not fully understood. The mortality and sterility of Drosophila melanogaster were assessed after feeding with 1M erythritol for 72 h and 96 h, and gene expression profiles were further compared through RNA sequencing. Enrichment analysis of GO and KEGG revealed that expressions of the adipokinetic hormone gene (Akh), amylase gene (Amyrel), α-glucosidase gene (Mal-B1/2, Mal-A1-4, Mal-A7/8), and triglyceride lipase gene (Bmm) were significantly up-regulated, while insulin-like peptide genes (Dilp2, Dilp3 and Dilp5) were dramatically down-regulated. Seventeen genes associated with eggshell assembly, including Dec-1 (down 315-fold), Vm26Ab (down 2014-fold) and Vm34Ca (down 6034-fold), were significantly down-regulated or even showed no expression. However, there were no significant differences in the expression of three diuretic hormone genes (DH44, DH31, CAPA) and eight aquaporin genes (Drip, Big brain, AQP, Eglp1, Eglp2, Eglp3, Eglp4 and Prip) involved in osmolality regulation (all p value > 0.05). We concluded that erythritol, a competitive inhibitor of α-glucosidase, severely reduced substrates and enzyme binding, inhibiting effective carbohydrate hydrolysis in the midgut and eventually causing death due to energy deprivation. It was clear that Drosophila melanogaster did not die from the osmolality of the hemolymph. Our findings elucidate the molecular mechanism underlying the mortality and sterility in Drosophila melanogaster induced by erythritol feeding. It also provides an important theoretical basis for the application of erythritol as an environmentally friendly pesticide. Full article