Non-Aquaporin Water Channels.

Water transport through membrane is so intricate that there are still some debates. AQPs are entirely accepted to allow water transmembrane movement depending on osmotic gradient. Cotransporters and uniporters, however, are also concerned in water homeostasis. UT-B has a single-channel water permeability that is similar to AQP1. CFTR was initially thought as a water channel but now not believed to transport water directly. By cotransporters, such as KCC4, NKCC1, SGLT1, GAT1, EAAT1, and MCT1, water is transported by water osmosis coupling with substrates, which explains how water is transported across the isolated small intestine. This chapter provides information about water transport mediated by other membrane proteins except AQPs.

Ganoderic acid A is the effective ingredient of Ganoderma triterpenes in retarding renal cyst development in polycystic kidney disease.

Autosomal dominant polycystic kidney disease (ADPKD) is one of the most common life-threatening monogenetic diseases characterized by progressive enlargement of fluid-filled renal cysts. Our previous study has shown that Ganoderma triterpenes (GT) retards PKD renal cyst development. In the present study we identified the effective ingredient of GT in suppression of kidney cyst development. Using an in vitro MDCK cystogenesis model, we identified ganoderic acid A (GA-A) as the most promising candidate among the 12 ganoderic acid (GA) monomers. We further showed that GA-A (6.25-100 µM) significantly inhibited cyst growth in MDCK cyst model and embryonic kidney cyst model in vitro, and the inhibitory effect was reversible. In kidney-specific Pkd1 knockout (kPKD) mice displaying severe cystic kidney disease, administration of GA-A (50 mg· kg-1 ·d-1, sc) significantly attenuated renal cyst development. In both MDCK cells and kidney of kPKD mice, we revealed that GA-A dose-dependently downregulated the Ras/MAPK signaling pathway. The expression of proliferating cell nuclear antigen (PCNA) was also suppressed, suggesting a possible effect of GA-A on cell proliferation. These experimental data suggest that GA-A may be the main ingredient of GT as a potential therapeutic reagent for treating ADPKD.

Multiple-Purpose Connectivity Map Analysis Reveals the Benefits of Esculetin to Hyperuricemia and Renal Fibrosis.

Hyperuricemia (HUA) is a risk factor for chronic kidney disease (CKD). Serum uric acid (SUA) levels in CKD stage 3-4 patients closely correlate with hyperuricemic nephropathy (HN) morbidity. New uric acid (UA)-lowering strategies are required to prevent CKD. The multiple-purpose connectivity map (CMAP) was used to discover potential molecules against HUA and renal fibrosis. We used HUA and unilateral ureteral occlusion (UUO) model mice to verify renoprotective effects of molecules and explore related mechanisms. In vitro experiments were performed in HepG2 and NRK-52E cells induced by UA. Esculetin was the top scoring compound and lowered serum uric acid (SUA) levels with dual functions on UA excretion. Esculetin exerted these effects by inhibiting expression and activity of xanthine oxidase (XO) in liver, and modulating UA transporters in kidney. The mechanism by which esculetin suppressed XO was related to inhibiting the nuclear translocation of hexokinase 2 (HK2). Esculetin was anti-fibrotic in HUA and UUO mice through inhibiting TGF-ß1-activated profibrotic signals. The renoprotection effects of esculetin in HUA mice were associated with lower SUA, alleviation of oxidative stress, and inhibition of fibrosis. Esculetin is a candidate urate-lowering drug with renoprotective activity and the ability to inhibit XO, promote excretion of UA, protect oxidative stress injury, and reduce renal fibrosis.

Ganoderma Lucidum Polysaccharide Peptide Alleviates Hepatoteatosis via Modulating Bile Acid Metabolism Dependent on FXR-SHP/FGF.

BACKGROUND/AIMS: Non-alcoholic fatty liver disease (NAFLD) encompasses a series of pathologic changes ranging from steatosis to steatohepatitis, which may progress to cirrhosis and hepatocellular carcinoma. The purpose of this study was to determine whether ganoderma lucidum polysaccharide peptide (GLPP) has therapeutic effect on NAFLD. METHODS: Ob/ ob mouse model and ApoC3 transgenic mouse model were used for exploring the effect of GLPP on NAFLD. Key metabolic pathways and enzymes were identified by metabolomics combining with KEGG and PIUmet analyses and key enzymes were detected by Western blot. Hepatosteatosis models of HepG2 cells and primary hepatocytes were used to further confirm the therapeutic effect of GLPP on NAFLD. RESULTS: GLPP administrated for a month alleviated hepatosteatosis, dyslipidemia, liver dysfunction and liver insulin resistance. Pathways of glycerophospholipid metabolism, fatty acid metabolism and primary bile acid biosynthesis were involved in the therapeutic effect of GLPP on NAFLD. Detection of key enzymes revealed that GLPP reversed low expression of CYP7A1, CYP8B1, FXR, SHP and high expression of FGFR4 in ob/ob mice and ApoC3 mice. Besides, GLPP inhibited fatty acid synthesis by reducing the expression of SREBP1c, FAS and ACC via a FXR-SHP dependent mechanism. Additionally, GLPP reduced the accumulation of lipid droplets and the content of TG in HepG2 cells and primary hepatocytes induced by oleic acid and palmitic acid. CONCLUSION: GLPP significantly improves NAFLD via regulating bile acid synthesis dependent on FXR-SHP/FGF pathway, which finally inhibits fatty acid synthesis, indicating that GLPP might be developed as a therapeutic drug for NAFLD.

Water Transport Mediated by Other Membrane Proteins.

Water transport through membrane is so intricate that there are still some debates. (Aquaporins) AQPs are entirely accepted to allow water transmembrane movement depending on osmotic gradient. Cotransporters and uniporters , however, are also concerned in water homeotatsis. Urea transporter B (UT-B) has a single-channel water permeability that is similar to AQP1. Cystic fibrosis transmembrane conductance regulator (CFTR ) was initially thought as a water channel but now not believed to transport water directly. By cotranporters, water is transported by water osmosis coupling with substrates, which explains how water is transported across the isolated small intestine. This chapter provides information about water transport mediated by other membrane proteins except AQPs .

Construction of tissue-engineered vascular grafts with enhanced patency by integrating heparin, cell-adhesive peptide, and carbon monoxide nanogenerators into acellular blood vessels.

Small-diameter tissue-engineered vascular grafts (sdTEVGs) have garnered significant attention as a potential treatment modality for vascular bypass grafting and replacement therapy. However, the intimal hyperplasia and thrombosis are two major complications that impair graft patency during transplantation. To address this issue, we fabricated the covalent-organic framework (COF)-based carbon monoxide (CO) nanogenerator-and co-immobilized with LXW-7 peptide and heparin to establish a multifunctional surface on TEVGs constructed from acellular blood vessels for preventing thrombosis and stenosis. The cell-adhesive peptide LXW-7 could capture endothelial-forming cells (EFCs) to promote endothelialization, while the antithrombotic molecule heparin prevented thrombus formation. The reactive oxygen species (ROS)-triggered CO release suppressed the adhesion and activation of macrophages, leading to the reduction of ROS and inflammatory factors. As a result, the endothelial-to-mesenchymal transition (EndMT) triggered by inflammation was restricted, facilitating the maintenance of the homeostasis of the neo-endothelium and preventing pathological remodeling in TEVGs. When transplanted in vivo, these vascular grafts exhibited negligible intimal hyperplasia and remained patent for 3 months. This achievement provided a novel approach for constructing antithrombotic and anti-hyperplastic TEVGs.

High urea induces anxiety disorders associated with chronic kidney disease by promoting abnormal proliferation of OPC in amygdala.

Chronic kidney disease (CKD) with anxiety disorder is of a great concern due to its high morbidity and mortality. Urea, as an important toxin in CKD, is not only a pathological factor for complications in patients with CKD, but also is accumulated in the brain of aging and neurodegenerative diseases. However, the pathological role and underlying regulatory mechanism of urea in CKD related mood disorders have not been well established. We previously reported a depression phenotype in mice with abnormal urea metabolism. Since patients with depression are more likely to suffer from anxiety, we speculate that high urea may be an important factor causing anxiety in CKD patients. In adenine-induced CKD mouse model and UT-B-/- mouse model, multiple behavioral studies confirmed that high urea induces anxiety-like behavior. Single-cell transcriptome revealed that down-regulation of Egr1 induced compensatory proliferation of oligodendrocyte progenitor cells (OPC). Myelin-related signaling pathways of oligodendrocytes (OL) were change significant in the urea accumulation amygdala. The study showed that high urea downregulated Egr1 with subsequent upregulation of ERK pathways in OPCs. These data indicate that the pathological role and molecular mechanism of high urea in CKD-related anxiety, and provide objective serological indicator and a potential new drug target for the prevention and treatment of anxiety in CKD patients.

Programmed Release METTL3-14 Inhibitor Microneedle Protects Myocardial Function by Reducing Drp1 m6A Modification-Mediated Mitochondrial Fission.

M6A modification is an RNA-important processing event mediated by methyltransferases METTL3 and METTL14 and the demethylases. M6A dynamic changes after myocardial infarction (MI), involved in the massive loss of cardiomyocytes due to hypoxia, as well as the recruitment and activation of myofibroblasts. Balanced mitochondrial fusion and fission are essential to maintain intracardiac homeostasis and reduce poststress myocardial remodeling. Double-layer programmed drug release microneedle (DPDMN) breaks the limitations of existing therapeutic interventions in one period or one type of cells, and multitargeted cellular combination has more potential in MI therapy. By employing hypoxia-ischemic and TGF-ß1-induced fibrosis cell models, we found that METTL3-14 inhibition effectively decreased cardiomyocyte death through the reduction of mitochondrial fragmentation and inhibiting myofibrillar transformation. DPDMN treatment of MI in rat models showed improved cardiac function and decreased infarct size and fibrosis level, demonstrating its superior effectiveness. The DPDMN delivers METTL3 inhibitor swiftly in the early phase to rescue dying cardiomyocytes and slowly in the late phase to achieve long-term suppression of fibroblast over proliferation, collagen synthesis, and deposition. RIP assay and mechanistic investigation confirmed that METTL3 inhibition reduced the translation efficiency of Drp1 mRNA by 5'UTR m6A modification, thus decreasing the Drp1 protein level and mitochondrial fragment after hypoxic-ischemic injury. This project investigated the efficacy of DPDMNs-loaded METTL3 inhibitor in MI treatment and the downstream signaling pathway proteins, providing an experimental foundation for the translation of the utility, safety, and versatility of microneedle drug delivery for MI into clinical applications.

Ganoderma lucidum polysaccharides ameliorates D-galactose-induced aging salivary secretion disorders by upregulating the rhythm and aquaporins.

Longer-term deterioration in saliva secretion has been observed to occur in response to aging. The functional deterioration of the salivary gland damages swallowing and chewing abilities and consequently reduces life quality of the elderly. There are, however, only a few proven effective treatments for aging salivary secretion disorders. Ganoderma lucidum polysaccharide (GLP) has been applied to treat various diseases because of its safety, efficacy, and low cost. We investigated the protective effect of GLP on the submandibular gland (SMG) during aging. D-galactose (D-gal) was used to treat the aging mice, and the body weight, water consumption, saliva secretion, and flow rate were measured after 6 weeks of modeling. Micromorphological changes of the SMG were assessed by hematoxylin-eosin staining and transmission electron microscopy. RT-qPCR and Western blot were used to detect the expression of apoptotic proteins and inflammatory cytokines. Aquaporins (AQPs) and rhythmic protein expression were analyzed by immunohistochemistry and immunofluorescence. The results showed that GLP effectively promoted the expression of AQP5, AQP4, and AQP1, inhibited the release of TNF-α, IL-6, and Bax, and reduced inflammation and apoptosis. Further experiments showed that GLP promoted the up-regulation of core clock genes and proteins and restored the co-localized expression of CLOCK and AQP5 that were weakened during aging, helping to attenuate aging-induced weight loss, decreased salivation, and structural and functional damage. The findings of this work contribute to understanding the nature of age-related modifications in SMG by identifying changes in AQP5 expression and regulatory mechanisms linked to SMG dysfunction during aging. GLP is a potential drug for maintaining healthy salivary gland (SG) status and preventing SG deficiency in the elderly.

Expression of Urea Transporter B in Normal and Injured Brain.

Urea transporter B (UT-B) is a membrane channel protein widely distributed in mammals, and plays a significant physiological role by regulating urea and water transportation in different tissues. More and more studies have found that UT-B is related to neurological diseases, including myelinopathy and depression. When urea accumulates in the brains of UT-B knockout mice, the synaptic plasticity of neurons is reduced, and the morphology and function of glial cells are also changed. However, the distribution and expression change of UT-B remain unclear. The purpose of this study is to determine the expression characteristics of UT-B in the brain. Through single-cell RNA sequencing, UT-B was found to express universally and substantially throughout the various cells in the central nervous system except for endothelial and smooth muscle cells. UT-B was detected in the third cerebral ventricular wall, granule cell layer of the dentate gyrus, and other parts of the hippocampal, cerebral cortex, substantia nigra, habenular, and lateral hypothalamic nucleus by immunohistochemistry. Compared with the membrane expression of UT-B in glial cells, the subcellular localization of UT-B is in the Golgi apparatus of neurons. Further, the expression of UT-B was regulated by osmotic pressure in vitro. In the experimental traumatic brain injury model (TBI), the number of UT-B positive neurons near the ipsilateral cerebral cortex increased first and then decreased over time, peaking at the 24 h. We inferred that change in UT-B expression after the TBI was an adaptation to changed urea levels. The experimental data suggest that the UT-B may be a potential target for the treatment of TBI and white matter edema.

Inhibition of histone acetyltransferase GCN5 extends lifespan in both yeast and human cell lines.

Histone acetyltransferases (HATs) are important enzymes that transfer acetyl groups onto histones and thereby regulate both gene expression and chromosomal structures. Previous work has shown that the activation of sirtuins, which are histone deacetylases, can extend lifespan. This suggests that inhibiting HATs may have a similar beneficial effect. In the present study, we utilized a range of HAT inhibitors or heterozygous Gcn5 and Ngg1 mutants to demonstrate marked yeast life extension. In human cell lines, HAT inhibitors and selective RNAi-mediated Gcn5 or Ngg1 knockdown reduced the levels of aging markers and promoted proliferation in senescent cells. Furthermore, this observed lifespan extension was associated with the acetylation of histone H3 rather than that of H4. Specifically, it was dependent upon H3K9Ac and H3K18Ac modifications. We also found that the ability of caloric restriction to prolong lifespan is Gcn5-, Ngg1-, H3K9-, and H3K18-dependent. Transcriptome analysis revealed that these changes were similar to those associated with heat shock and were inversely correlated with the gene expression profiles of aged yeast and aged worms. Through a bioinformatic analysis, we also found that HAT inhibition activated subtelomeric genes in human cell lines. Together, our results suggest that inhibiting the HAT Gcn5 may be an effective means of increasing longevity.

Berberine ameliorates cellular senescence and extends the lifespan of mice via regulating p16 and cyclin protein expression.

Although aging and senescence have been extensively studied in the past few decades, however, there is lack of clinical treatment available for anti-aging. This study presents the effects of berberine (BBR) on the aging process resulting in a promising extension of lifespan in model organisms. BBR extended the replicative lifespan, improved the morphology, and boosted rejuvenation markers of replicative senescence in human fetal lung diploid fibroblasts (2BS and WI38). BBR also rescued senescent cells with late population doubling (PD). Furthermore, the senescence-associated ß-galactosidase (SA-ß-gal)-positive cell rates of late PD cells grown in the BBR-containing medium were ~72% lower than those of control cells, and its morphology resembled that of young cells. Mechanistically, BBR improved cell growth and proliferation by promoting entry of cell cycles from the G0 or G1 phase to S/G2 -M phase. Most importantly, BBR extended the lifespan of chemotherapy-treated mice and naturally aged mice by ~52% and ~16.49%, respectively. The residual lifespan of the naturally aged mice was extended by 80%, from 85.5 days to 154 days. The oral administration of BBR in mice resulted in significantly improved health span, fur density, and behavioral activity. Therefore, BBR may be an ideal candidate for the development of an anti-aging medicine.

High urea induces depression and LTP impairment through mTOR signalling suppression caused by carbamylation.

BACKGROUND: Urea, the end product of protein metabolism, has been considered to have negligible toxicity for a long time. Our previous study showed a depression phenotype in urea transporter (UT) B knockout mice, which suggests that abnormal urea metabolism may cause depression. The purpose of this study was to determine if urea accumulation in brain is a key factor causing depression using clinical data and animal models. METHODS: A meta-analysis was used to identify the relationship between depression and chronic diseases. Functional Magnetic Resonance Imaging (fMRI) brain scans and common biochemical indexes were compared between the patients and healthy controls. We used behavioural tests, electrophysiology, and molecular profiling techniques to investigate the functional role and molecular basis in mouse models. FINDINGS: After performing a meta-analysis, we targeted the relevance between chronic kidney disease (CKD) and depression. In a CKD mouse model and a patient cohort, depression was induced by impairing the medial prefrontal cortex. The enlarged cohort suggested that urea was responsible for depression. In mice, urea was sufficient to induce depression, interrupt long-term potentiation (LTP) and cause loss of synapses in several models. The mTORC1-S6K pathway inhibition was necessary for the effect of urea. Lastly, we identified that the hydrolysate of urea, cyanate, was also involved in this pathophysiology. INTERPRETATION: These data indicate that urea accumulation in brain is an independent factor causing depression, bypassing the psychosocial stress. Urea or cyanate carbamylates mTOR to inhibit the mTORC1-S6K dependent dendritic protein synthesis, inducing impairment of synaptic plasticity in mPFC and depression-like behaviour. CKD patients may be able to attenuate depression only by strict management of blood urea.