The Evolutionary Aspects of Aquaporin Family

Membrane tension-dependent conformational change of Isoleucine 106 of loop B diminishes water permeability in FaPIP2;1

Aquaporins (AQPs) are membrane proteins specialized in facilitating water transport across membranes. Mechanical stress is one of the various stimuli that regulate AQPs. Briefly, there are several studies that report a decrease in permeability upon an increase in membrane tension. However, the molecular details of this mechanosensitive (MS) response are still a matter of debate. Our work attempts to close that gap in knowledge by providing evidence of a conformational change that occurs inside the pore of the strawberry aquaporin FaPIP2;1. Via osmotic shock experiments and molecular dynamics (MD) simulations, we found that a residue of loop B, I106, is key to the blocking of the permeation pathway and such a change is almost exclusively found under membrane tensile stress. In detail, osmotic shock experiments exhibited a nonlinear increment in water fluxes for increasing osmolarities, evidencing a decrease in the FaPIP2;1 permeability. MD simulations under membrane tension showed the same trend, with a significant increase in states with a low water permeability. The latter was correlated with a conformational change in I106 that generates a permeation barrier of around 18 kJ mol-1, effectively closing the pore. This work constitutes the first report of a PIP type aquaporin reacting to tensile stress in the membrane. Our findings could pave the way to test whether this conformational change is also responsible for mechanical gating in the other MS aquaporins, both those already reported and those still waiting to be found.

Aquaporins in Biliary Function: Pathophysiological Implications and Therapeutic Targeting

Aquaporins (AQPs) are transmembrane proteins permeable to water and a series of small solutes. AQPs play a key role in pathways of hepatobiliary secretion at the level of the liver, bile ducts, and gallbladder. AQP8 and -9 are pivotal in facilitating the osmotic water movement of hepatic bile, which is composed of 95% water. In the biliary tract, AQP1 and -4 are involved in the rearrangement of bile composition by mechanisms of reabsorption/secretion of water. In the gallbladder, AQP1 and -8 are also involved in trans-epithelial bidirectional water flow with the ultimate goal of bile concentration. Pathophysiologically, AQPs have been indicated as players in several hepatobiliary disorders, including cholestatic diseases and cholesterol cholelithiasis. Research on AQP function and the modulation of AQP expression is in progress, with the identification of potent and homolog-specific compounds modulating the expression or inhibiting these membrane channels with promising pharmacological developments. This review summarizes the contribution of AQPs in physiological and pathophysiological stages related to hepatobiliary function.

Aquaporin (AQP) gene family in Buffalo and Goat: Molecular characterization and their expression analysis

Aquaporins (AQPs) are essential membrane proteins facilitating water and small solute transport across cell membranes. Mammals have approximately 13 paralogs of AQPs that may have evolved through gene duplication events. These genes are present in two separate clusters within the genome. In the present study, comprehensive 13 AQP genes (AQP0-12) were cloned and characterized in buffalo and goat. The protein coding region of AQPs in both species ranged from 729 to 990 bps, corresponding to 263-330 amino acid residues. Two important residues including NPA motifs and ar/R selectivity filter were found conserved in all AQPs, except for AQP7, 11 and 12. AQP0, 2, 4, 5, 7, 9, 12 showed tissue-restricted expression, whereas AQP1, 3, 8, and 11 exhibited ubiquitous expression across several tissues. AQP10 was identified as a pseudogene in all artiodactyls. Transcript variants were identified in buffalo and goat, where some variants of goat AQP5 and 6 lacked important motifs. Evolutionary analysis indicated positive selection at or near the NPA motifs and ar/R selectivity filter of AQP0, 3, 6, 7, and 10 that may alter its structure and function. This study is crucial for future investigations aiming to study the molecular mechanisms of AQPs in response to various physiological conditions.

Aquaporin Channels in Skin Physiology and Aging Pathophysiology: Investigating Their Role in Skin Function and the Hallmarks of Aging

This study examines the critical role of aquaporins (AQPs) in skin physiology and aging pathophysiology. The skin plays a vital role in maintaining homeostasis by acting as a protective barrier against external pathogens and excessive water loss, while also contributing to the appearance and self-esteem of individuals. Key physiological features, such as elasticity and repair capability, are essential for its proper function. However, with aging, these characteristics deteriorate, reducing the skin's ability to tolerate environmental stressors which contribute to external aging as well as internal aging processes, which negatively affect barrier function, immune response, and overall well-being. AQPs, primarily known for facilitating water transport, are significant for normal skin functions, including hydration and the movement of molecules like glycerol and hydrogen peroxide, which influence various cellular processes and functions. In this context, we categorized aquaporin dysfunction into several hallmarks of aging, including mitochondrial dysfunction, cellular senescence, stem cell depletion, impaired macroautophagy, dysbiosis, and inflamm-aging. Eight aquaporins (AQP1, 3, 5, 7, 8, 9, 10, and 11) are expressed in various skin cells, regulating essential processes such as cell migration, proliferation, differentiation, and also immune response. Dysregulation or altered expression of these proteins can enhance skin aging and related pathologies by activating these hallmarks. This study provides valuable insights into the potential of targeting aquaporins to mitigate skin aging and improve skin physiologic functions.

Stichoposide C and Rhizochalin as Potential Aquaglyceroporin Modulators

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.

A novel aquaporin Aagp contributes to Streptococcus suis H2O2 efflux and virulence

Streptococcus suis is a bacterium that can cause infections in pigs and humans. Although oxidative stress is common occurrence during bacterial growth and infection, the regulation networks of S. suis under oxidative stress remain poorly understood. To address this, we utilized RNA-Seq to reveal the transcriptional landscape of S. suis in response to H2O2 stress. We identified novel genes responsible for S. suis resistance to oxidative stress, including those involved in DNA repair or protection, and essential for the biosynthesis of amino acids and nucleic acids. In addition, we found that a novel aquaporin, Aagp, belonging to atypical aquaglyceroporins and widely distributed in diverse S. suis serotypes, plays a crucial role during H2O2 stress. By performing oxidative stress assays and measuring the intracellular H2O2 concentrations of the wild-type strain and Aagp mutants during H2O2 stress, we found that Aagp facilitated H2O2 efflux. Additionally, we found that Aagp might be involved in glycerol transport, as shown by the growth inhibition and H2O2 production in the presence of glycerol. Mice infection experiments indicated that Aagp contributed to S. suis virulence. This study contributes to understanding the mechanism of S. suis oxidative stress response, S. suis pathogenesis, and the function of aquaporins in prokaryotes.

Ion Channels and Ionotropic Receptors in Astrocytes: Physiological Functions and Alterations in Alzheimer's Disease and Glioblastoma

The human brain is composed of nearly one hundred billion neurons and an equal number of glial cells, including macroglia, i.e., astrocytes and oligodendrocytes, and microglia, the resident immune cells of the brain. In the last few decades, compelling evidence has revealed that glial cells are far more active and complex than previously thought. In particular, astrocytes, the most abundant glial cell population, not only take part in brain development, metabolism, and defense against pathogens and insults, but they also affect sensory, motor, and cognitive functions by constantly modulating synaptic activity. Not surprisingly, astrocytes are actively involved in neurodegenerative diseases (NDs) and other neurological disorders like brain tumors, in which they rapidly become reactive and mediate neuroinflammation. Reactive astrocytes acquire or lose specific functions that differently modulate disease progression and symptoms, including cognitive impairments. Astrocytes express several types of ion channels, including K+, Na+, and Ca2+ channels, transient receptor potential channels (TRP), aquaporins, mechanoreceptors, and anion channels, whose properties and functions are only partially understood, particularly in small processes that contact synapses. In addition, astrocytes express ionotropic receptors for several neurotransmitters. Here, we provide an extensive and up-to-date review of the roles of ion channels and ionotropic receptors in astrocyte physiology and pathology. As examples of two different brain pathologies, we focus on Alzheimer's disease (AD), one of the most diffuse neurodegenerative disorders, and glioblastoma (GBM), the most common brain tumor. Understanding how ion channels and ionotropic receptors in astrocytes participate in NDs and tumors is necessary for developing new therapeutic tools for these increasingly common neurological conditions.

The Role of Aquaporins in Epileptogenesis-A Systematic Review

Aquaporins (AQPs) are a family of membrane proteins involved in the transport of water and ions across cell membranes. AQPs have been shown to be implicated in various physiological and pathological processes in the brain, including water homeostasis, cell migration, and inflammation, among others. Epileptogenesis is a complex and multifactorial process that involves alterations in the structure and function of neuronal networks. Recent evidence suggests that AQPs may also play a role in the pathogenesis of epilepsy. In animal models of epilepsy, AQPs have been shown to be upregulated in regions of the brain that are involved in seizure generation, suggesting that they may contribute to the hyperexcitability of neuronal networks. Moreover, genetic studies have identified mutations in AQP genes associated with an increased risk of developing epilepsy. Our review aims to investigate the role of AQPs in epilepsy and seizure onset from a pathophysiological point of view, pointing out the potential molecular mechanism and their clinical implications.

Xerostomia and Its Cellular Targets

Xerostomia, the subjective feeling of a dry mouth associated with dysfunction of the salivary glands, is mainly caused by radiation and chemotherapy, various systemic and autoimmune diseases, and drugs. As saliva plays numerous essential roles in oral and systemic health, xerostomia significantly reduces quality of life, but its prevalence is increasing. Salivation mainly depends on parasympathetic and sympathetic nerves, and the salivary glands responsible for this secretion move fluid unidirectionally through structural features such as the polarity of acinar cells. Saliva secretion is initiated by the binding of released neurotransmitters from nerves to specific G-protein-coupled receptors (GPCRs) on acinar cells. This signal induces two intracellular calcium (Ca2+) pathways (Ca2+ release from the endoplasmic reticulum and Ca2+ influx across the plasma membrane), and this increased intracellular Ca2+ concentration ([Ca2+]i) causes the translocation of the water channel aquaporin 5 (AQP5) to the apical membrane. Consequently, the GPCR-mediated increased [Ca2+]i in acinar cells promotes saliva secretion, and this saliva moves into the oral cavity through the ducts. In this review, we seek to elucidate the potential of GPCRs, the inositol 1,4,5-trisphosphate receptor (IP3R), store-operated Ca2+ entry (SOCE), and AQP5, which are essential for salivation, as cellular targets in the etiology of xerostomia.

Uptake of Selenite by Rahnella aquatilis HX2 Involves the Aquaporin AqpZ and Na+/H+ Antiporter NhaA

Microbial transformation of selenite [Se(IV)] to elemental selenium nanoparticles (SeNPs) is known to be an important process for removing toxic soluble selenium (Se) oxyanions and recovery of Se from the environment as valuable nanoparticles. However, the mechanism of selenite uptake by microorganisms, the first step through which Se exerts its cellular function, remains not well studied. In this study, the effects of selenite concentration, time, pH, metabolic inhibitors, and anionic analogues on selenite uptake in Rahnella aquatilis HX2 were investigated. Selenite uptake by R. aquatilis HX2 was concentration- and time-dependent, and its transport activity was significantly dependent on pH. In addition, selenite uptake in R. aquatilis HX2 was significantly inhibited by the aquaporin inhibitor AgNO₃ and sulfite (SO₃^2-), and partially inhibited by carbonyl cyanide m-chlorophenyl hydrazone (CCCP) and 2,4-dinitrophenol (2,4-DNP) treatments. Three mutants with in-frame deletions of aqpZ, glpF, and nhaA genes were constructed. The transport assay showed that the water channel protein AqpZ, and not GlpF, was a key channel of selenite uptake by R. aquatilis HX2, and sulfite and selenite had a common uptake pathway. In addition, the Na⁺/H⁺ antiporter NhaA is also involved in selenite uptake in R. aquatilis HX2.

Aquaporins Display a Diversity in their Substrates

Aquaporins constitute a family of transmembrane proteins that function to transport water and other small solutes across the cell membrane. Aquaporins family members are found in diverse life forms. Aquaporins share the common structural fold consisting of six transmembrane alpha helices with a central water-transporting channel. Four such monomers assemble together to form tetramers as their biological unit. Initially, aquaporins were discovered as water-transporting channels, but several studies supported their involvement in mediating the facilitated diffusion of different solutes. The so-called water channel is able to transport a variety of substrates ranging from a neutral molecule to a charged molecule or a small molecule to a bulky molecule or even a gas molecule. This article gives an overview of a diverse range of substrates conducted by aquaporin family members. Prime focus is on human aquaporins where aquaporins show a wide tissue distribution and substrate specificity leading to various physiological functions. This review also highlights the structural mechanisms leading to the transport of water and glycerol. More research is needed to understand how one common fold enables the aquaporins to transport an array of solutes.

Aquaporins in Cardiovascular System

Recent studies have shown that aquaporins (AQPs) are involved in the regulation of cardiovascular function and the development of related diseases, especially in cerebral ischemia, congestive heart failure, hypertension, and angiogenesis. Therefore, further studies are needed to elucidate the mechanism accounting for the association between AQPs and vascular function-related diseases, which may lead to novel approaches to the prevention and treatment of those diseases. Here we will discuss the expression and physiological roles of AQPs in vascular tissues and summarize recent progress in the research on AQPs related cardiovascular diseases.

Evolutionary Overview of Aquaporin Superfamily

Aquaporins (AQPs) are present not only in three domains of life, bacteria, eukaryotes, and archaea, but also in viruses. With the accumulating arrays of AQP superfamily, the evolutional relationship has attracted much attention with multiple publications on "the genome-wide identification and phylogenetic analysis" of AQP superfamily. A pair of NPA boxes forming a pore is highly conserved throughout the evolution and renders key residues for the classification of AQP superfamily into four groups: AQP1-like, AQP3-like, AQP8-like, and AQP11-like. The complexity of AQP family has mostly been achieved in nematodes and subsequent evolution has been directed toward increasing the number of AQPs through whole-genome duplications (WGDs) to extend the tissue specific expression and regulation. The discovery of the intracellular AQP (iAQP: AQP8-like and AQP11-like) and substrate transports by the plasma membrane AQP (pAQP: AQP1-like and AQP3-like) have accelerated the AQP research much more toward the transport of substrates with complex profiles. This evolutionary overview based on a simple classification of AQPs into four subfamilies will provide putative structural, functional, and localization information and insights into the role of AQP as well as clues to understand the complex diversity of AQP superfamily.

Protein Structure and Modification of Aquaporins

Aquaporins (AQPs) allow water molecules and other small, neutral solutes to quickly pass through membrane. The protein structures of AQPs solved by crystallographic methods or cryo-electron microscopy technology show that AQP monomer consists of six membrane-spanning alpha-helices that form the central water-transporting pore. AQP monomers assemble to form tetramers, forming the functional units in the membrane, to transport water or other small molecules. The biological functions of AQPs are regulated by posttranslational modifications, e.g., phosphorylation, ubiquitination, glycosylation, subcellular distribution, degradation and protein interactions. Modifications of AQP combined with structural properties contribute to a better functional mechanism of AQPs. Insight into the molecular mechanisms responsible for AQP modifications as well as gating and transport properties proved to be fundamental to the development of new therapeutic targets or reliable diagnostic and prognostic biomarkers.

The Hidden Intricacies of Aquaporins: Remarkable Details in a Common Structural Scaffold

Evolution turned aquaporins (AQPs) into the most efficient facilitators of passive water flow through cell membranes at no expense of solute discrimination. In spite of a plethora of solved AQP structures, many structural details remain hidden. Here, by combining extensive sequence- and structural-based analysis of a unique set of 20 non-redundant high-resolution structures and molecular dynamics simulations of four representatives, key aspects of AQP stability, gating, selectivity, pore geometry, and oligomerization, with a potential impact on channel functionality, are identified. The general view of AQPs possessing a continuous open water pore is challenged and it is depicted that AQPs' selectivity is not exclusively shaped by pore-lining residues but also by the relative arrangement of transmembrane helices. Moreover, this analysis reveals that hydrophobic interactions constitute the main determinant of protein thermal stability. Finally, a numbering scheme of the conserved AQP scaffold is established, facilitating direct comparison of, for example, disease-causing mutations and prediction of potential structural consequences. Additionally, the results pave the way for the design of optimized AQP water channels to be utilized in biotechnological applications.

SP1-Induced Upregulation of lncRNA LINC00659 Promotes Tumour Progression in Gastric Cancer by Regulating miR-370/AQP3 Axis

Growing evidence demonstrates that long noncoding RNAs (lncRNAs) play critical roles in various human tumors. LncRNA LINC00659 (LINC00659) is a newly identified lncRNA and its roles in tumors remain largely unclear. In this study, we elucidated the potential functions and molecular mechanisms of LINC00659 on the biological behaviors of gastric cancer (GC), and also explored its clinical significance. We firstly demonstrated that LINC00659 levels were distinctly up-regulated in both GC specimens and cells using bioinformatics analysis and RT-PCR. The results of ChIP assays and luciferase reporter assays confirmed that upregulation of LINC00659 was activated by SP1 in GC. Clinical assays revealed that higher levels of LINC00659 were associated with TNM stage, lymphatic metastasis, and poorer prognosis. Moreover, LINC00659 was confirmed to be an independent prognostic marker for the patients with GC using multivariate assays. Lost-of-function assays indicated that knockdown of LINC00659 suppressed the proliferation, metastasis, and EMT progress of GC cells in vitro. Mechanistic investigation indicated that LINC00659 served as a competing endogenous RNA (ceRNA) for miR-370, thereby resulting in the upregulation of leading to the depression of its endogenous target gene AQP3. Overall, our present study revealed that the LINC00659/miR-370/AQP3 axis contributes to GC progression, which may provide clues for the exploration of cancer biomarkers and therapeutic targets for GC.

Midbody-Localized Aquaporin Mediates Intercellular Lumen Expansion During Early Cleavage of an Invasive Freshwater Bivalve

Intercellular lumen formation is a crucial aspect of animal development and physiology that involves a complex interplay between the molecular and physical properties of the constituent cells. Embryos of the invasive freshwater mussel Dreissena rostriformis are ideal models for studying this process due to the large intercellular cavities that readily form during blastomere cleavage. Using this system, we show that recruitment of the transmembrane water channel protein aquaporin exclusively to the midbody of intercellular cytokinetic bridges is critical for lumenogenesis. The positioning of aquaporin-positive midbodies thereby influences the direction of cleavage cavity expansion. Notably, disrupting cytokinetic bridge microtubules impairs not only lumenogenesis but also cellular osmoregulation. Our findings reveal a simple mechanism that provides tight spatial and temporal control over the formation of luminal structures and likely plays an important role in water homeostasis during early cleavage stages of a freshwater invertebrate species.

An aquaporin gene MdPIP1;2 from Malus domestica confers salt tolerance in transgenic Arabidopsis

Aquaporins are known as water channel proteins. In this study, an aquaporin gene MdPIP1;2 was cloned from Malus domestica cv. Qinguan encoding a protein of 289 amino acids that formed the typical structure of aquaporin by six transmembrane domains, two asparagine-proline-alanine motifs, aromatic/arginine filter, and Forger's position. MdPIP1;2 was highly expressed in the water-sensitive or water-requiring tissues, and upregulated by salt and PEG stresses. MdPIP1;2 transgenic Arabidopsis exhibited enhanced salt stress tolerance with less Na ⁺ accumulation, lower malondialdehyde (MDA) content, lower electrolyte leakage (EL) level, and higher superoxide dismutase (SOD) and peroxidase (POD) activities compared with WT plants. Additionally, transcriptome analysis indicated MdPIP1;2 transgenic Arabidopsis could present healthier growth and development condition probably through regulating morphological structures and accumulating specific secondary metabolites under salt stress. Our results are a useful reference for better understanding the biological function of aquaporin in apple tree, especially in plant response to abiotic stress.

Human Norovirus Induces Aquaporin 1 Production by Activating NF-κB Signaling Pathway

Human norovirus (HuNoV) is one of the major pathogens of acute nonbacterial gastroenteritis. Due to the lack of a robust and reproducible in vitro culture system and an appropriate animal model, the mechanism underlying HuNoV-caused diarrhea remains unknown. In the current study, we found that HuNoV transfection induced the expression of aquaporin 1 (AQP1), which was further confirmed in the context of virus infection, whereas the enterovirus EV71 (enterovirus 71) did not have such an effect. We further revealed that VP1, the major capsid protein of HuNoV, was crucial in promoting AQP1 expression. Mechanistically, HuNoV induces AQP1 production through the NF-κB signaling pathway via inducing the expression, phosphorylation and nuclear translocation of p65. By using a model of human intestinal epithelial barrier (IEB), we demonstrated that HuNoV and VP1-mediated enhancement of small molecule permeability is associated with the AQP1 channel. Collectively, we revealed that HuNoV induced the production of AQP1 by activating the NF-κB signaling pathway. The findings in this study provide a basis for further understanding the significance of HuNoV-induced AQP1 expression and the potential mechanism underlying HuNoV-caused diarrhea.

Diversification of the aquaporin family in geographical isolated oyster species promote the adaptability to dynamic environments

BACKGROUND

The diversified aquaporin (AQP) family that was derived from gene duplication and subsequent functional differentiation play critical roles in multiple physiological processes and in adaptation to the dynamic environments during the evolutionary process. Oysters are a group of bivalve fauna in Mollusca that were widely distributed around the world and show extraordinary adaptation to harsh environments. However, knowledge is lacking with the diversity and evolution of the AQP family in oysters, even in molluscs.

RESULTS

Here, we performed a comprehensive analysis of the AQP family in three geographical isolated oyster species that are native to different environments. Genome distribution and phylogenetic analysis revealed that the expansion of the AQP family in oysters were attributed to tandem duplication. Synteny analysis indicated that large-scale inversions lead to the independent duplication or deletion of the AQPs after speciation. As a consequence, these independent duplication events contributed to the diversification of the AQP family in different oysters. Pore pattern analysis suggested that the duplicated AQPs in oysters were highly diversified in inner surface profiles, implying the subsequent functional differentiation. The comparison conducted based on the transcriptome data demonstrated that the functional differentiated AQP family members in oysters may play critical roles in maintaining the balance between the stationary homeostasis and dynamic environments.

CONCLUSIONS

Our observation provides evidence for the correlation between the duplicated and functional differentiated AQP family and the adaptation to stationary life under dynamic environments in oysters. Additionally, it also broadens our knowledge of the evolution of AQP family in molluscs.

Mitogen-Activated Protein Kinase and Aquaglyceroporin Gene Expression in Treatment Failure Leishmania major

PURPOSE

Leishmaniasis comprises various clinical forms mainly including cutaneous, muco-cutaneous, and visceral leishmaniasis; caused by Leishmania species. Antimoniate is the first-line treatment but some cases showed no response to treatment in the worldwide. In this study, mitogen-activated protein kinase (MAPK) and aquaglyceroporin 1 (AQP1) gene expressions were assessed in treatment failure clinical isolates of Leishmania major. Also, molecular and phylogenic analyses of the mentioned isolates were performed.

METHODS

Samples were obtained from the patients with suspicious CL referred to the laboratory of Diagnosis Center, Gorgan Province, Iran, from October 2016 to December 2019. Detection and identification of the parasite was performed. The genes expressions of MAPK1 and AQP1 were done using SYBR Green real-time PCR. The AQP1 gene from the isolates with treatment failure was sequenced and analyzed using BLAST and multiple alignments. The phylogenic analysis was done using MEGA7. The statistical analysis was done using SPSS 16.0 by non-parametric Mann-Whitney U test.

RESULTS

All clinical isolates were detected L. major. The mean AQP1 and MAPK1 gene expressions in treatment failure isolates were 58.71 and 6.139 fold less than the ones in treatment response isolates, respectively. Based on the AQP1 gene sequence, a nucleotide change of aspartic acid with asparagine at the site 234 was observed. Phylogenic tree analysis showed three groups with the minimum dissimilarity of 0.008 between TF isolates with the standard L. major strains.

CONCLUSION

We showed that MAPK1 and AQP1 may have critical roles in response to antimoniate in clinical isolates L. major in this study.

Effects of a Chinese herbal extract on the intestinal tract and aquaporin in Adriamycin-induced nephropathy

Wuling Decoction is a traditional Chinese medicine that has been used to open knots, benefit water, transform Qi, return fluid, and has a significant effect on strengthening the spleen and removing dampness. To explore the effects of Wuling Decoction on the intestinal tract and aquaporin in Adriamycin-induced nephropathy, 45 specific pathogen free (SPF) Wistar rats were randomly divided into a blank control group (5 rats), Dosing control group (10 rats), Adriamycin nephropathy model group (10 rats), diarrhea group (10 rats), and an Adriamycin nephropathy diarrhea model group (10 rats). The tissue localization of aquaporin (AQP) was determined by immunohistochemistry. The expression of AQP mRNA and protein was measured by RT-PCR and western blot analysis, respectively. The results indicated that Wuling Decoction causes excretion of AQP2 through the urine, regulates AQP2 levels, and exerts diuretic and anti-diarrheal effects. It also regulates the levels of antidiuretic hormone (ADH) and arginine vasopressin (AVP), affects water absorption rate, and reduces the level of cyclic adenosine monophosphate (cAMP) in each tissue, thus reducing the absorption of AQP2 to water. Wuling Decoction promoted AQP2 expression in the nephropathy model group and inhibited AQP2 expression in the diarrhea group. Wuling Decoction increased the expression of aquaporin in the intestinal tract, reduced the water content of stool by promoting the absorption of water in the intestinal tract, inhibited the expression of aquaporin and its regulatory factors in nephridia tissue, and reduced the reabsorption of water to increase urine volume, to decrease the occurrence of diarrhea.

A Novel Aquaporin Subfamily Imports Oxygen and Contributes to Pneumococcal Virulence by Controlling the Production and Release of Virulence Factors

Aquaporins, integral membrane proteins widely distributed in organisms, facilitate the transport of water, glycerol, and other small uncharged solutes across cellular membranes and play important physiological roles in eukaryotes. However, characterizations and physiological functions of the prokaryotic aquaporins remain largely unknown. Here, we report that Streptococcus pneumoniae (pneumococcus) AqpC (Pn-AqpC), representing a new aquaporin subfamily possessing a distinct substrate-selective channel, functions as an oxygen porin by facilitating oxygen movement across the cell membrane and contributes significantly to pneumococcal virulence. The use of a phosphorescent oxygen probe showed that Pn-AqpC facilitates oxygen permeation into pneumococcal and Pn-AqpC-expressing yeast cells. Reconstituting Pn-AqpC into liposomes prepared with pneumococcal and Escherichia coli cellular membranes further verified that Pn-AqpC transports O₂ but not water or glycerol. Alanine substitution showed that Pro232 in the substrate channel is key for Pn-AqpC in O₂ transport. The deletion of Pn-aqpC significantly reduced H₂O₂ production and resistance to H₂O₂ and NO of pneumococci, whereas low-H₂O₂ treatment helped the ΔPn-aqpC mutant resist higher levels of H₂O₂ and even NO, indicating that Pn-AqpC-facilitated O₂ permeation contributes to pneumococcal resistance to H₂O₂ and NO. Remarkably, the lack of Pn-aqpC alleviated cell autolysis, thus reducing pneumolysin (Ply) release and decreasing the hemolysis of pneumococci. Accordingly, the ΔPn-aqpC mutant markedly reduced survival in macrophages, decreased damage to macrophages, and significantly reduced lethality in mice. Therefore, the oxygen porin Pn-AqpC, through modulating H₂O₂ production and pneumolysin release, the two major pneumococcal virulence factors, controls the virulence of pneumococcus. Pn-AqpC orthologs are widely distributed in various pneumococcal serotypes, highlighting that the oxygen porin is important for pneumococcal pathogenicity.

Bird aquaporins: Molecular machinery for urine concentration

Water conservation is one of the most challenging processes for terrestrial vertebrates and is necessary for their survival. Birds are the only vertebrate animals other than mammals that have the ability to concentrate their urine. Previously, we identified and characterized aquaporins (AQP)1-4 responsible for urine concentration in Japanese quail kidneys. Today, a total of 13 orthologs for these genes have been reported in birds. Bird AQPs can be classified into four subfamilies: 1) Classical AQPs (AQP0-5 and novel member, AQP4-like) that conserve the selectivity filter; 2) aquaglyceroporins (AQP3, 7, 9 and 10) that retain an aspartic acid residue in the second NPA box and expand the pore to accept larger molecules; 3) unorthodox AQPs (AQP11-12) which structurally resemble their mammalian counterparts; 4) AQP8-type, a subfamily that differs from mammalian AQP8. Interestingly, over the course of time, birds lost their mammalian counterpart AQP6 but obtained a novel AQP4-like aquaporin member. In quail and/or chicken kidneys, at least six AQPs are expressed. Quail AQP1 (qAQP1) is expressed in both cortical and medullary proximal tubules but is absent in the descending limb (DL) and the thick ascending limb (TAL), supporting our previous finding that the DL and TAL are water impermeable. AQP2, an arginine vasotocin (AVT)-sensitive water channel, is exclusively expressed in the principal cells of the collecting duct (CD). AQP4 is unlikely to participate in free water resorption from the collecting duct (CD), and only AQP3 may represent an exit pathway for water reabsorbed apically via AQP2. While AQP9 is not expressed in mammalian kidneys, AQP9 was recently found in chicken kidneys. This review summarizes the current knowledge of the structure, function and expression of bird AQPs.

Skin aquaporins as druggable targets: Promoting health by addressing the disease

Skin is the most vulnerable organ of the human body since it is the first line of defense, covering the entire external body surface. Additionally, skin has a critical role in thermoregulation, sensation, immunological surveillance, and biochemical processes such as Vitamin D₃ production by ultraviolet irradiation. The ability of the skin layers and resident cells to maintain skin physiology, such as hydration, regulation of keratinocytes proliferation and differentiation and wound healing, is supported by key proteins such as aquaporins (AQPs) that facilitate the movements of water and small neutral solutes across membranes. Various AQP isoforms have been detected in different skin-resident cells where they perform specific roles, and their dysregulation has been associated with several skin pathologies. This review summarizes the current knowledge of AQPs involvement in skin physiology and pathology, highlighting their potential as druggable targets for the treatment of skin disorders.

Involvement of aquaglyceroporins in energy metabolism in health and disease

Aquaglyceroporins are a group of the aquaporin (AQP) family of transmembrane water channels. While AQPs facilitate the passage of water, small solutes, and gases across biological membranes, aquaglyceroporins allow passage of water, glycerol, urea and some other solutes. Thanks to their glycerol permeability, aquaglyceroporins are involved in energy homeostasis. This review provides an overview of what is currently known concerning the functional implication and control of aquaglyceroporins in tissues involved in energy metabolism, i.e. liver, adipose tissue and endocrine pancreas. The expression, role and (dys)regulation of aquaglyceroporins in disorders affecting energy metabolism, and the potential relevance of aquaglyceroporins as drug targets to treat the alterations of the energy balance is also addressed.

Melatonin improves the effect of cryopreservation on human oocytes by suppressing oxidative stress and maintaining the permeability of the oolemma

Cryopreservation causes cryoinjury to oocytes and impairs their developmental competence. Melatonin (MLT) can improve the effect of cryopreservation in animal oocytes. However, no such studies on human oocytes have been reported. In this study, collected in vitro-matured human oocytes were randomly divided into the following groups: fresh group, MLT-treated cryopreservation (MC) group, and no-MLT-treated cryopreservation (NC) group. After vitrification and warming, viable oocytes from these three groups were assessed for their mitochondrial function, ultrastructure, permeability of oolemma, early apoptosis, developmental competence, and cryotolerance-related gene expression. First, fluorescence staining results revealed that oocytes from the 10^-9  M subgroup showed the lowest intracellular reactive oxygen species and Ca²⁺ levels and highest mitochondrial membrane potential among the MC subgroups (10^-11 , 10^-9 , 10^-7 , and 10^-5  M). In subsequent experiments, oocytes from the 10^-9  M-MC group were observed to maintain the normal ultrastructural features and the permeability of the oolemma. Compared with those of the oocytes in the NC group, the early apoptosis rate significantly decreased (P < .01), whereas both the high-quality cleavage embryo and blastocyst rates significantly increased (both P < .05) in the oocytes of the 10^-9  M-MC group. Finally, single-cell RNA sequencing and immunofluorescence results revealed that aquaporin (AQP) 1/2/11 gene expression and AQP1 protein expression were upregulated in the MC group. Therefore, these results suggest that MLT can improve the effect of cryopreservation on human oocytes by suppressing oxidative stress and maintaining the permeability of the oolemma.

Altered Iris Aquaporin Expression and Aqueous Humor Osmolality in Glaucoma

Purpose

Aquaporins (AQPs) facilitate transmembrane osmotic water transport and may play a role in iris fluid conductivity, which is implicated in the pathophysiology of glaucoma. In this study, we compared the iris expression of AQPs and aqueous osmolality between primary angle closure glaucoma (PACG), primary open-angle glaucoma (POAG), and nonglaucoma eyes.

Methods

AQP1-5 transcripts from a cohort of 36 PACG, 34 POAG and 26 nonglaucoma irises were measured by quantitative real-time PCR. Osmolality of aqueous humor from another cohort of 49 PACG, 50 POAG, and 50 nonglaucoma eyes were measured using an osmometer. The localization of AQP1 in both glaucoma and nonglaucoma irises was determined by immunofluorescent analysis.

Results

Of the five AQP genes evaluated, AQP1 and AQP2 transcripts were significantly upregulated in both PACG (3.48- and 8.07-fold, respectively) and POAG (3.12- and 11.58-fold, respectively) irises relative to nonglaucoma counterparts. The aqueous osmolalities of PACG (303.68 mmol/kg) and POAG (300.79 mmol/kg) eyes were significantly lower compared to nonglaucoma eyes (312.6 mmol/kg). There was no significant difference in expression of AQP transcripts or aqueous osmolality between PACG and POAG eyes.

Conclusions

PACG and POAG eyes featured significant increase in AQP1 and AQP2 expression in the iris and reduced aqueous osmolality compared to nonglaucoma eyes. These findings suggest that the iris may be involved in altered aqueous humor dynamics in glaucoma pathophysiology. Because PACG did not differ from POAG in both properties studied, it is likely that they are common to glaucoma disease in general.

Targeting Aquaporins in Novel Therapies for Male and Female Breast and Reproductive Cancers

Aquaporins are membrane channels in the broad family of major intrinsic proteins (MIPs), with 13 classes showing tissue-specific distributions in humans. As key physiological modulators of water and solute homeostasis, mutations, and dysfunctions involving aquaporins have been associated with pathologies in all major organs. Increases in aquaporin expression are associated with greater severity of many cancers, particularly in augmenting motility and invasiveness for example in colon cancers and glioblastoma. However, potential roles of altered aquaporin (AQP) function in reproductive cancers have been understudied to date. Published work reviewed here shows distinct classes aquaporin have differential roles in mediating cancer metastasis, angiogenesis, and resistance to apoptosis. Known mechanisms of action of AQPs in other tissues are proving relevant to understanding reproductive cancers. Emerging patterns show AQPs 1, 3, and 5 in particular are highly expressed in breast, endometrial, and ovarian cancers, consistent with their gene regulation by estrogen response elements, and AQPs 3 and 9 in particular are linked with prostate cancer. Continuing work is defining avenues for pharmacological targeting of aquaporins as potential therapies to reduce female and male reproductive cancer cell growth and invasiveness.

Sevoflurane modulates AQPs (1,5) expression and endoplasmic reticulum stress in mice lung with allergic airway inflammation

Sevoflurane was found to show protective roles in mice with asthma, however, the mechanism of which needs further exploring. Aquaporins (AQPs) have been demonstrated to be involved in the pathogenesis of asthma, while endoplasmic reticulum stress has been reported to be related to many inflammatory diseases and involved in protein processing, including AQPs. The present study aimed to determine the role of sevoflurane in AQPs (AQP1,3,4,5) expression in mice with allergic airway inflammation and the probable mechanism. The increased number of inflammatory cells infiltrating the lung tissue, and the elevated levels of tumor necrosis factor-α (TNF-α) and interleukin (IL) 13 (IL-13) were all decreased after sevoflurane treatment (all P<0.05). Meanwhile, mRNA levels of AQP1 and AQP5 but not AQP3 and AQP4 were decreased in ovalbumin (OVA)-induced allergic mice lung. Both the decreased mRNA expression and protein levels of AQP1 and AQP5 in allergic lung tissues were reversed by sevoflurane treatment. Furthermore, we established that sevoflurane inhibited the OVA-induced protein increase in the endoplasmic reticulum (ER) stress markers BiP and C/EBP homologous protein (CHOP). Collectively, these findings suggested that sevoflurane modulated the expression and protein level of AOPs (AQP1, AQP5) as well as inhibited ER stress response in OVA-induced allergic airway inflammation of mice.

Expression, Distribution and Role of Aquaporins in Various Rhinologic Conditions

Aquaporins (AQPs) are water-specific membrane channel proteins that regulate cellular and organismal water homeostasis. The nose, an organ with important respiratory and olfactory functions, is the first organ exposed to external stimuli. Nose-related topics such as allergic rhinitis (AR) and chronic rhinosinusitis (CRS) have been the subject of extensive research. These studies have reported that mechanisms that drive the development of multiple inflammatory diseases that occur in the nose and contribute to the process of olfactory recognition of compounds entering the nasal cavity involve the action of water channels such as AQPs. In this review, we provide a comprehensive overview of the relationship between AQPs and rhinologic conditions, focusing on the current state of knowledge and mechanisms that link AQPs and rhinologic conditions. Key conclusions include the following: (1) Various AQPs are expressed in both nasal mucosa and olfactory mucosa; (2) the expression of AQPs in these tissues is different in inflammatory diseases such as AR or CRS, as compared with that in normal tissues; (3) the expression of AQPs in CRS differs depending on the presence or absence of nasal polyps; and (4) the expression of AQPs in tissues associated with olfaction is different from that in the respiratory epithelium.

Polyploidization and pseudogenization in allotetraploid frog Xenopus laevis promote the evolution of aquaporin family in higher vertebrates

BACKGROUND

Aquaporins (AQPs), as members of the major intrinsic protein (MIP) superfamily, facilitated the permeation of water and other solutes and are involved in multiple biological processes. AQP family exists in almost all living organisms and is highly diversified in vertebrates in both classification and function due to genome wide duplication. While some AQP orthologs have been lost in higher vertebrates through evolution.

RESULT

Genome-wide comparative analyses of the AQP family between allotetraploid frog Xenopus laevis (Xla) and diploid frog Xenopus tropicalis (Xtr), based on the genome assemblies, revealed that the number of AQPs in Xla genome nearly doubled that in Xtr (32 vs. 19). Synteny analysis indicated that the distribution of the retained AQPs in Xla subgenomes (17 in Xla. L, the longer homeolog of Xla genome and 15 in Xla. S, the shorter homeolog of Xla genome) were highly symmetrical when compared with that in Xtr genome. Remarkably, two members in Xla. L and four members in Xla. S were lost through evolution. Blast analysis revealed that the lost AQPs in Xla are pseudogenized via either the deletion of some exons or some single nucleotide insertions or deletions that lead the reading frame shift. Additionally, comparative genomic analyses suggested that the orthologs of AQPs that with one copy absence in Xla are also prone to be lost in higher vertebrates.

CONCLUSION

This study revealed that polyploidization and subsequent pseudogenization and deletion in Xla genome promote the evolution of AQP family in higher vertebrates. Besides, our results would also contribute to understanding the evolution of AQP family.

Insight into Salivary Gland Aquaporins

The main role of salivary glands (SG) is the production and secretion of saliva, in which aquaporins (AQPs) play a key role by ensuring water flow. The AQPs are transmembrane channel proteins permeable to water to allow water transport across cell membranes according to osmotic gradient. This review gives an insight into SG AQPs. Indeed, it gives a summary of the expression and localization of AQPs in adult human, rat and mouse SG, as well as of their physiological role in SG function. Furthermore, the review provides a comprehensive view of the involvement of AQPs in pathological conditions affecting SG, including Sjögren's syndrome, diabetes, agedness, head and neck cancer radiotherapy and SG cancer. These conditions are characterized by salivary hypofunction resulting in xerostomia. A specific focus is given on current and future therapeutic strategies aiming at AQPs to treat xerostomia. A deeper understanding of the AQPs involvement in molecular mechanisms of saliva secretion and diseases offered new avenues for therapeutic approaches, including drugs, gene therapy and tissue engineering. As such, AQP5 represents a potential therapeutic target in different strategies for the treatment of xerostomia.

Ectopic expression of a rice plasma membrane intrinsic protein (OsPIP1;3) promotes plant growth and water uptake

Plasma membrane intrinsic proteins (PIPs) are known to be major facilitators of the movement of a number of substrates across cell membranes. From a drought-resistant cultivar of Oryza sativa (rice), we isolated an OsPIP1;3 gene single-nucleotide polymorphism (SNP) that is mostly expressed in rice roots and is strongly responsive to drought stress. Immunocytochemistry showed that OsPIP1;3 majorly accumulated on the proximal end of the endodermis and the cell surface around the xylem. Expression of GFP-OsPIP1;3 alone in Xenopus oocytes or rice protoplasts showed OsPIP1;3 mislocalization in the endoplasmic reticulum (ER)-like neighborhood, whereas co-expression of OsPIP2;2 recruited OsPIP1;3 to the plasma membrane and led to a significant enhancement of water permeability in oocytes. Moreover, reconstitution of 10×His-OsPIP1;3 in liposomes demonstrated water channel activity, as revealed by stopped-flow light scattering. Intriguingly, by patch-clamp technique, we detected significant NO₃^- conductance of OsPIP1;3 in mammalian cells. To investigate the physiological functions of OsPIP1;3, we ectopically expressed the OsPIP1;3 gene in Nicotiana benthamiana (tobacco). The transgenic tobacco plants exhibited higher photosynthesis rates, root hydraulic conductivity (Lp_r ) and water-use efficiency, resulting in a greater biomass and a higher resistance to water deficit than the wild-type did. Further experiments suggested that heterologous expression of OsPIP1;3 in cyanobacterium altered bacterial growth under different conditions of CO₂ gas supply. Overall, besides shedding light on the multiple functions played by OsPIP1;3, this work provides insights into the translational value of plant AQPs.

[MicroRNA and their potential role in the pathogenesis of hemorrhagic stroke]

Spontaneous (non-traumatic) intracerebral hemorrhage (ICH), or hemorrhagic stroke, is a common and serious disease with high morbidity and mortality. Current methods of treating hemorrhagic stroke, from conservative to surgical, are insufficient, which justifies the continuation of the study of this condition, including cellular and molecular changes that occur during a stroke. MicroRNAs (miRNAs) are a class of small non-coding RNAs that play an important role in post-transcriptional regulation of gene expression. MicroRNAs are involved in almost all biological processes, including cell proliferation, apoptosis and cell differentiation, and are also key substances in pathophysiological processes in many diseases, and therefore they can be both potential biomarkers and new therapeutic targets in cancer, degenerative and cardiovascular disease. In recent years, a number of studies have been aimed at studying the role of microRNAs in pathophysiological processes in hemorrhagic stroke, such as apoptosis, inflammation, oxidative stress, violation of the blood-brain barrier (BBB) and cerebral edema. The results of the studies demonstrated that changes in miRNA expression may be associated with the prognosis of ICH. In this article, we consider studies related to miRNAs and hemorrhagic stroke, and clarify the complex relationship between them.

Glucocorticoid gene regulation of aquaporin-7

AQP7 is the primary glycerol transporter in white (WAT) and brown (BAT) adipose tissues. There are immediate and quantitatively important actions of cortisone over the expression of AQP7 in murine and human adipocytes. Short-term response (minutes) of cortisone treatment result in an mRNA overexpression in white and brown differentiated adipocytes (between 1.5 and 6 folds). Conversely, long-term response (hours or days) result in decreased mRNA expression. The effects observed on AQP7 mRNA expression upon cortisone treatment in brown and white differentiated adipocytes are concordant with those observed for GK and HSD1B11.

Comparative transcriptome profiling of selected osmotic regulatory proteins in the gill during seawater acclimation of chum salmon (Oncorhynchus keta) fry

Salmonid fishes, chum salmon (Oncorhynchus keta) have the developed adaptive strategy to withstand wide salinity changes from the early life stage. This study investigated gene expression patterns of cell membrane proteins in the gill of chum salmon fry on the transcriptome level by tracking the salinity acclimation of the fish in changing environments ranging from freshwater (0 ppt) to brackish water (17.5 ppt) to seawater (35 ppt). Using GO analysis of DEGs, the known osmoregulatory genes and their functional groups such as ion transport, transmembrane transporter activity and metal ion binding were identified. The expression patterns of membrane protein genes, including pump-mediated protein (NKA, CFTR), carrier-mediated protein (NKCC, NHE3) and channel-mediated protein (AQP) were similar to those of other salmonid fishes in the smolt or adult stages. Based on the protein-protein interaction analysis between transmembrane proteins and other related genes, we identified osmotic-related genes expressed with salinity changes and analyzed their expression patterns. The findings of this study may facilitate the disentangling of the genetic basis of chum salmon and better able an understanding of the osmophysiology of the species.

Deep-Fried Atractylodis Rhizoma Protects against Spleen Deficiency-Induced Diarrhea through Regulating Intestinal Inflammatory Response and Gut Microbiota

According to the theories of traditional Chinese medicine, spleen deficiency often leads to diarrhea, and deep-fried Atractylodis Rhizoma (DAR) is commonly used for the treatment. However, the association between spleen deficiency and diarrhea remains unclear. The present study aimed to investigate the therapeutic effect of DAR for the treatment of diarrhea caused by spleen deficiency and analyze the related mechanisms. It was found that a high dose group of an ethanolic extract of deep-fried Atractylodis Rhizoma (EEDAR-H) significantly inhibited weight loss, diarrhea, and pathological changes in colon tissue induced by rhubarb. EEDAR-H was found to significantly reduce the level of intestinal inflammatory cytokines and increase the expression of gastrointestinal motility hormones. In addition, EEDAR-H significantly increased the expression of aquaporin 3 (AQP3) and aquaporin 8 (AQP8) and restored abnormal water metabolism; Shen-Ling-Bai-Zhu-San (SLBZS) induced the same effect as EEDAR-H. Additional tests on the mechanism found that EEDAR-H and SLBZS promoted the integrity of the intestinal barrier. Both significantly increased the expression of the tight junction protein ZO-1 and Occludin, inhibited the phosphorylation of p38MAPK and MLC, and significantly reduced the expression levels of PAR-2. Analysis of the gut microbiota indicated that overall changes in its structure were reversed after treatment with EEDAR-H or SLBZS, in addition to significant modulation of the abundance of different phyla. At the genus level, EEDAR-H or SLBZS significantly reduced the levels of potential pathogens and increased those of beneficial bacteria.

Prokaryotic Aquaporins

Aquaporins are integral membrane proteins that facilitate the diffusion of water and other small, uncharged solutes across the cellular membrane and are widely distributed in organisms from humans to bacteria. However, the characteristics of prokaryotic aquaporins remain largely unknown. We investigated the distribution and sequence characterization of aquaporins in prokaryotic organisms and summarized the transport characteristics, physiological functions, and regulatory mechanisms of prokaryotic aquaporins. Aquaporin homologues were identified in 3315 prokaryotic genomes retrieved from the Kyoto Encyclopedia of Genes and Genomes (KEGG) database, but the protein clustering pattern is not completely congruent with the phylogeny of the species that carry them. Moreover, prokaryotic aquaporins display diversified aromatic/arginine constriction region (ar/R) amino acid compositions, implying multiple functions. The typical water and glycerol transport characterization, physiological functions, and regulations have been extensively studied in Escherichia coli AqpZ and GlpF. A Streptococcus aquaporin has recently been verified to facilitate the efflux of endogenous H₂O₂, which not only contributes to detoxification but also to species competitiveness, improving our understanding of prokaryotic aquaporins. Furthermore, recent studies revealed novel regulatory mechanisms of prokaryotic aquaporins at post-translational level. Thus, we propose that intensive investigation on prokaryotic aquaporins would extend the functional categories and working mechanisms of these ubiquitous, intrinsic membrane proteins.

Emergent Nanotechnological Strategies for Systemic Chemotherapy against Melanoma

Melanoma is an aggressive form of skin cancer, being one of the deadliest cancers in the world. The current treatment options involve surgery, radiotherapy, targeted therapy, immunotherapy and the use of chemotherapeutic agents. Although the last approach is the most used, the high toxicity and the lack of efficacy in advanced stages of the disease have demanded the search for novel bioactive molecules and/or efficient drug delivery systems. The current review aims to discuss the most recent advances on the elucidation of potential targets for melanoma treatment, such as aquaporin-3 and tyrosinase. In addition, the role of nanotechnology as a valuable strategy to effectively deliver selective drugs is emphasized, either incorporating/encapsulating synthetic molecules or natural-derived compounds in lipid-based nanosystems such as liposomes. Nanoformulated compounds have been explored for their improved anticancer activity against melanoma and promising results have been obtained. Indeed, they displayed improved physicochemical properties and higher accumulation in tumoral tissues, which potentiated the efficacy of the compounds in pre-clinical experiments. Overall, these experiments opened new doors for the discovery and development of more effective drug formulations for melanoma treatment.

Expression of aquaporins in inner ear disease

The inner ear is responsible for hearing and balance and consists of a membranous labyrinth within a bony labyrinth. The balance structure is divided into the otolith organ that recognizes linear acceleration and the semicircular canal that is responsible for rotational movement. The cochlea is the hearing organ. The external and middle ear are covered with skin and mucosa, respectively, and the space is filled with air, whereas the inner ear is composed of endolymph and perilymph. The inner ear is a fluid-filled sensory organ composed of hair cells with cilia on the upper part of the cells that convert changes in sound energy and balance into electric energy through the hair cells to transmit signals to the auditory nerve through synapses. Aquaporins (AQPs) are a family of transmembrane proteins present in all species that can be roughly divided into three subfamilies according to structure and function: 1) classical AQP, 2) aquaglyceroporin, and 3) superaquaporin. Currently, the subfamily of mammalian species is known to include 13 AQP members (AQP0-AQP12). AQPs have a variety of functions depending on their structure and are related to inner ear diseases such as Meniere's disease, sensorineural hearing loss, and presbycusis. Additional studies on the relationship between the inner ear and AQPs may be helpful in the diagnosis and treatment of inner ear disease. Laryngoscope, 130:1532-1539, 2020.

Identification of Ixodid Tick-Specific Aquaporin-1 Potential Anti-tick Vaccine Epitopes: An in-silico Analysis

Ticks are arthropod vectors of pathogens of both Veterinary and Public health importance. Acaricide application, which is currently the mainstay of tick control, is hampered by high cost, the need for regular application and a selection of multi-acaricide resistant tick populations. In light of this, future tick control approaches are poised to rely on the integration of rational acaricide application and other methods, such as vaccination. To contribute to systematic research-guided efforts to produce anti-tick vaccines, we carried out an in-silico analysis of tick aquaporin-1 (AQP1) protein in order to identify tick-specific AQP1 peptide motifs that can be used in future peptide anti-tick vaccine development. We carried out multiple sequence alignment (MSA), motif analysis, homology modeling, and structural analysis to identify tick-specific AQP1 peptide motifs. BepiPred, Chou and Fasman-Turn, Karplus and Schulz Flexibility, and Parker-Hydrophilicity prediction models were used to predict these motifs' potential to induce B cell mediated immune responses. The tick AQP1 (GenBankID: QDO67142.1) protein was largely similar to the bovine AQP1 (PDB:1J4N) (23 % sequence similarity; Structural superimposition of the homology model and 14JN homotetramers gave an RMSD = 3.269 while superimposition of a single chain gave an RMSD = 1.475). Tick and bovine AQP1 transmembrane domains were largely similar while their extracellular and cytoplasmic domain loops showed variation. Two tick-specific AQP1 peptide motifs; M7 (residues 106-125, p = 5.4e-25), and M8 (residues 85-104, p = 3.3e-24) were identified. These two motifs are located on the extra-cellular AQP1 domain. Motifs; M7 and M8 showed the highest Parker-Hydrophilicity prediction immunogenicity scores of 1.784 and 1.536, respectively. These two motifs can be a good starting point for the development of potential tick AQP1 peptide-based anti-tick vaccines. Further analyses such as molecular dynamics, in vitro assays, and in vivo immunization assays are required to validate these findings.

Plant Aquaporins: Diversity, Evolution and Biotechnological Applications

The plasma membrane forms a permeable barrier that separates the cytoplasm from the external environment, defining the physical and chemical limits in each cell in all organisms. The movement of molecules and ions into and out of cells is controlled by the plasma membrane as a critical process for cell stability and survival, maintaining essential differences between the composition of the extracellular fluid and the cytosol. In this process aquaporins (AQPs) figure as important actors, comprising highly conserved membrane proteins that carry water, glycerol and other hydrophilic molecules through biomembranes, including the cell wall and membranes of cytoplasmic organelles. While mammals have 15 types of AQPs described so far (displaying 18 paralogs), a single plant species can present more than 120 isoforms, providing transport of different types of solutes. Such aquaporins may be present in the whole plant or can be associated with different tissues or situations, including biotic and especially abiotic stresses, such as drought, salinity or tolerance to soils rich in heavy metals, for instance. The present review addresses several aspects of plant aquaporins, from their structure, classification, and function, to in silico methodologies for their analysis and identification in transcriptomes and genomes. Aspects of evolution and diversification of AQPs (with a focus on plants) are approached for the first time with the aid of the LCA (Last Common Ancestor) analysis. Finally, the main practical applications involving the use of AQPs are discussed, including patents and future perspectives involving this important protein family.

Identification of Sugarcane Host Factors Interacting with the 6K2 Protein of the Sugarcane Mosaic Virus

The 6K2 protein of potyviruses plays a key role in the viral infection in plants. In the present study, the coding sequence of 6K2 was cloned from Sugarcane mosaic virus (SCMV) strain FZ1 into pBT3-STE to generate the plasmid pBT3-STE-6K2, which was used as bait to screen a cDNA library prepared from sugarcane plants infected with SCMV based on the DUALmembrane system. One hundred and fifty-seven positive colonies were screened and sequenced, and the corresponding full-length genes were cloned from sugarcane cultivar ROC22. Then, 24 genes with annotations were obtained, and the deduced proteins were classified into three groups, in which eight proteins were involved in the stress response, 12 proteins were involved in transport, and four proteins were involved in photosynthesis based on their biological functions. Of the 24 proteins, 20 proteins were verified to interact with SCMV-6K2 by yeast two-hybrid assays. The possible roles of these proteins in SCMV infection on sugarcane are analyzed and discussed. This is the first report on the interaction of SCMV-6K2 with host factors from sugarcane, and will improve knowledge on the mechanism of SCMV infection in sugarcane.

Combining genome-wide and transcriptome-wide analyses reveal the evolutionary conservation and functional diversity of aquaporins in cotton

BACKGROUND

Aquaporins (AQPs) are integral membrane proteins from a larger family of major intrinsic proteins (MIPs) and function in a huge variety of processes such as water transport, plant growth and stress response. The availability of the whole-genome data of different cotton species allows us to study systematic evolution and function of cotton AQPs on a genome-wide level.

RESULTS

Here, a total of 53, 58, 113 and 111 AQP genes were identified in G. arboreum, G. raimondii, G. hirsutum and G. barbadense, respectively. A comprehensive analysis of cotton AQPs, involved in exon/intron structure, functional domains, phylogenetic relationships and gene duplications, divided these AQPs into five subfamilies (PIP, NIP, SIP, TIP and XIP). Comparative genome analysis among 30 species from algae to angiosperm as well as common tandem duplication events in 24 well-studied plants further revealed the evolutionary conservation of AQP family in the organism kingdom. Combining transcriptome analysis and Quantitative Real-time PCR (qRT-PCR) verification, most AQPs exhibited tissue-specific expression patterns both in G. raimondii and G. hirsutum. Meanwhile, a bias of time to peak expression of several AQPs was also detected after treating G. davidsonii and G. hirsutum with 200 mM NaCl. It is interesting that both PIP1;4 h/i/j and PIP2;2a/e showed the highly conserved tandem structure, but differentially contributed to tissue development and stress response in different cotton species.

CONCLUSIONS

These results demonstrated that cotton AQPs were structural conservation while experienced the functional differentiation during the process of evolution and domestication. This study will further broaden our insights into the evolution and functional elucidation of AQP gene family in cotton.

Comparative Analysis of the aquaporin Gene Family in 12 Fish Species

Simple Summary

Aquaporins (Aqps) are a group of membrane proteins. In this study, 166 Aqp genes were identified in 12 fish species. Gene organization, motif distribution, recombination, and selection pressure were performed to investigate their evolutionary characteristics. In addition, expression profiles of Aqps were also examined under pathogens infection and organophosphorus pesticide stress. This study will provide a useful reference for further functional study.

Abstract

Aquaporins (Aqps) are a class of water channel proteins that play key roles in many physiological functions and cellular processes. Here, we analyzed 166 putative Aqp genes in 12 fish species and divided them into four groups. Gene organization and motif distribution analyses suggested potentially conserved functions in each group. Several recombination events were identified in some members, which accelerate their divergence in evolution. Furthermore, a few positive selection sites were identified, and mutations at these sites could alter the stability of Aqp proteins. In addition, expression profiles of some Aqp genes under pathogen infection and organophosphorus pesticide stress were also investigated. The result implied that several Aqp genes may affect different immune responses and osmoregulation. This study provides a comparative analysis of the fish Aqp gene family to facilitate further functional analyses.

Omnipresent Maxwell's demons orchestrate information management in living cells

The development of synthetic biology calls for accurate understanding of the critical functions that allow construction and operation of a living cell. Besides coding for ubiquitous structures, minimal genomes encode a wealth of functions that dissipate energy in an unanticipated way. Analysis of these functions shows that they are meant to manage information under conditions when discrimination of substrates in a noisy background is preferred over a simple recognition process. We show here that many of these functions, including transporters and the ribosome construction machinery, behave as would behave a material implementation of the information-managing agent theorized by Maxwell almost 150 years ago and commonly known as Maxwell's demon (MxD). A core gene set encoding these functions belongs to the minimal genome required to allow the construction of an autonomous cell. These MxDs allow the cell to perform computations in an energy-efficient way that is vastly better than our contemporary computers.