Energy Transfer Between i-Motif DNA Encapsulated Silver Nanoclusters and Fluorescein Amidite Efficiently Visualizes the Redox State of Live Cells.

The redox regulation, maintaining a balance between oxidation and reduction in living cells, is vital for cellular homeostasis, intricate signaling networks, and appropriate responses to physiological and environmental cues. Here, a novel redox sensor, based on DNA-encapsulated silver nanoclusters (DNA/AgNCs) and well-defined chemical fluorophores, effectively illustrating cellular redox states in live cells is introduced. Among various i-motif DNAs, the photophysical property of poly-cytosines (C20)-encapsulated AgNCs that sense reactive oxygen species (ROS) is adopted. However, the sensitivity of C20/AgNCs is insufficient for evaluating ROS levels in live cells. To overcome this drawback, the ROS sensing mechanism of C20/AgNCs through gel electrophoresis, mass spectrometry, and small-angle X-ray scattering is primarily defined. Then, by tethering fluorescein amidite (FAM) and Cyanine 5 (Cy5) dyes to each end of the C20/AgNCs sensor, an Energy Transfer (ET) between AgNCs and FAM is achieved, resulting in intensified green fluorescence upon ROS detection. Taken together, the FAM-C20/AgNCs-Cy5 redox sensor enables dynamic visualization of intracellular redox states, yielding insights into oxidative stress-related processes in live cells.

A selective ER-phagy exerts neuroprotective effects via modulation of α-synuclein clearance in parkinsonian models.

The endoplasmic reticulum (ER) is selectively degraded by ER-phagy to maintain cell homeostasis. α-synuclein accumulates in the ER, causing ER stress that contributes to neurodegeneration in Parkinson's disease (PD), but the role of ER-phagy in α-synuclein modulation is largely unknown. Here, we investigated the mechanisms by which ER-phagy selectively recognizes α-synuclein for degradation in the ER. We found that ER-phagy played an important role in the degradation of α-synuclein and recovery of ER function through interaction with FAM134B, where calnexin is required for the selective FAM134B-mediated α-synuclein clearance via ER-phagy. Overexpression of α-synuclein in the ER of the substantia nigra (SN) resulted in marked loss of dopaminergic neurons and motor deficits, mimicking PD characteristics. However, enhancement of ER-phagy using FAM134B overexpression in the SN exerted neuroprotective effects on dopaminergic neurons and recovered motor performance. These data suggest that ER-phagy represents a specific ER clearance mechanism for the degradation of α-synuclein.

Uric acid regulates α-synuclein transmission in Parkinsonian models.

Ample evidence demonstrates that α-synuclein (α-syn) has a critical role in the pathogenesis of Parkinson's disease (PD) with evidence indicating that its propagation from one area of the brain to others may be the primary mechanism for disease progression. Uric acid (UA), a natural antioxidant, has been proposed as a potential disease modifying candidate in PD. In the present study, we investigated whether UA treatment modulates cell-to-cell transmission of extracellular α-syn and protects dopaminergic neurons in the α-syn-enriched model. In a cellular model, UA treatment decreased internalized cytosolic α-syn levels and neuron-to-neuron transmission of α-syn in donor-acceptor cell models by modulating dynamin-mediated and clathrin-mediated endocytosis. Moreover, UA elevation in α-syn-inoculated mice inhibited propagation of extracellular α-syn which decreased expression of phosphorylated α-syn in the dopaminergic neurons of the substantia nigra leading to their increased survival. UA treatment did not lead to change in markers related with autophagolysosomal and microglial activity under the same experimental conditions. These findings suggest UA may control the pathological conditions of PD via additive mechanisms which modulate the propagation of α-syn.

Priming mesenchymal stem cells with α-synuclein enhances neuroprotective properties through induction of autophagy in Parkinsonian models.

BACKGROUND: Mesenchymal stem cells (MSCs) may be one of candidates for disease-modifying therapy in Parkinsonian diseases. As knowledge regarding the therapeutic properties of MSCs accumulates, some obstacles still remain to be overcome, especially, successful clinical translation requires the development of culture systems that mimic the natural MSC niche, while allowing clinical-scale cell expansion without compromising quality and function of the cells. In recent years, priming approaches using bioactive peptide or complement components have been investigated to enhance the therapeutic potential of MSCs. METHODS: We investigated an innovative priming strategy by conditioning the MSCs with α-synuclein (α-syn). To induce priming, MSCs were treated with different concentrations of α-syn and various time course. We evaluated whether α-syn enhances stemness properties of MSCs and priming MSCs with α-syn would modulate autophagy-related gene expression profiles. RESULTS: Treatment of naïve MSCs with α-syn upregulated transcriptional factors responsible for regulation of stemness, which was associated with the elevated expression of genes involved in glycolysis and cell re-programming. Primed MSCs with α-syn enhanced the expression of autophagy-regulating miRNA, and exosomes derived from primed MSCs were packed with autophagy-associated miRNA. In α-syn-overexpressing neuronal cells, primed MSCs with α-syn enhanced neuronal viability relative to naïve MSCs, through the induction of autophagy and lysosome activity. Animal study using an α-syn-overexpressing mice showed that the pro-survival effect of MSCs on dopaminergic neurons was more prominent in primed MSC-treated mice compared with that in naïve MSC-treated mice. CONCLUSIONS: The present data suggest that MSC priming with α-syn exerts neuroprotective effects through augmented stemness and possibly the enhancement of autophagy-mediated α-syn modulation in Parkinsonian models.

Uric Acid Enhances Neurogenesis in a Parkinsonian Model by Remodeling Mitochondria.

Background: Adult neurogenesis is the process of generating new neurons to enter neural circuits and differentiate into functional neurons. However, it is significantly reduced in Parkinson's disease (PD). Uric acid (UA), a natural antioxidant, has neuroprotective properties in patients with PD. This study aimed to investigate whether UA would enhance neurogenesis in PD. Methods: We evaluated whether elevating serum UA levels in a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced parkinsonian mouse model would restore neurogenesis in the subventricular zone (SVZ). For a cellular model, we primary cultured neural precursor cells (NPCs) from post-natal day 1 rat and evaluated whether UA treatment promoted cell proliferation against 1-methyl-4-phenylpyridinium (MPP+). Results: Uric acid enhanced neurogenesis in both in vivo and in vitro parkinsonian model. UA-elevating therapy significantly increased the number of bromodeoxyuridine (BrdU)-positive cells in the SVZ of PD animals as compared to PD mice with normal UA levels. In a cellular model, UA treatment increased the expression of Ki-67. In the process of modulating neurogenesis, UA elevation up-regulated the expression of mitochondrial fusion markers. Conclusion: In MPTP-induced parkinsonian model, UA probably enhanced neurogenesis via regulating mitochondrial dynamics, promoting fusion machinery, and inhibiting fission process.

Memantine exerts neuroprotective effects by modulating α-synuclein transmission in a parkinsonian model.

Ample evidence has demonstrated that α-Synuclein can propagate from one area of the brain to others via cell-to-cell transmission, which might be the underlying mechanism for pathological propagation and the disease progression of Parkinson's disease (PD). Recent reports have demonstrated cell surface receptor-mediated cell-to-cell transmission of α-synuclein. Memantine decreased the levels of internalized cytosolic α-synuclein and led to attenuation in α-synuclein-induced cell death. Specifically, memantine attenuated α-synuclein-induced expression of clathrin and EEA1, and increased expression of NR2A subunits. Moreover, memantine inhibited propagation of extracellular α-synuclein and thus, decreased the expression of the phosphorylated form of α-synuclein in dopaminergic neurons of the substantia nigra, which was accompanied by increased survival of dopaminergic neurons with functional improvement of motor deficits. The present study demonstrated that memantine modulates extracellular α-synuclein propagation by inhibiting interactions between α-synuclein and NR2A subunits, which leads to neuroprotective effects on nigral dopaminergic neurons against α-synuclein-enriched conditions. The repositioning use of memantine in α-synuclein propagation needs to be further evaluated in patients with α-synucleinopathies as an effective therapeutic approach.

Automated cortical thickness measurement of the mandibular condyle head on CBCT images using a deep learning method.

This study proposes a deep learning model for cortical bone segmentation in the mandibular condyle head using cone-beam computed tomography (CBCT) and an automated method for measuring cortical thickness with a color display based on the segmentation results. In total, 12,800 CBCT images from 25 normal subjects, manually labeled by an oral radiologist, served as the gold-standard. The segmentation model combined a modified U-Net and a convolutional neural network for target region classification. Model performance was evaluated using intersection over union (IoU) and the Hausdorff distance in comparison with the gold standard. The second automated model measured the cortical thickness based on a three-dimensional (3D) model rendered from the segmentation results and presented a color visualization of the measurements. The IoU and Hausdorff distance showed high accuracy (0.870 and 0.928 for marrow bone and 0.734 and 1.247 for cortical bone, respectively). A visual comparison of the 3D color maps showed a similar trend to the gold standard. This algorithm for automatic segmentation of the mandibular condyle head and visualization of the measured cortical thickness as a 3D-rendered model with a color map may contribute to the automated quantification of bone thickness changes of the temporomandibular joint complex on CBCT.

Priming mesenchymal stem cells with uric acid enhances neuroprotective properties in parkinsonian models.

Mesenchymal stem cells (MSCs) are a potential source of cell-based disease-modifying therapy in Parkinsonian disorders. A promising approach to develop in vitro culture methods that mimic natural MSC niche is cell priming. Uric acid (UA), a powerful antioxidant, scavenges reactive oxygen species, which has a vital role in maintaining self-renewal and differentiation potential of MSCs. Here, we demonstrated that UA treatment in naïve MSCs stimulated glycolysis and upregulated transcriptional factors responsible for regulation of stemness, leading to increase in the expression levels of osteogenesis-, adipogenesis-, and chondrogenesis-related genes. UA-primed MSCs had more enhanced neuroprotective properties in cellular and parkinsonian animal models compared to naïve MSCs by inhibiting apoptotic signaling pathways. Additionally, expression of miR-137 and miR-145 was decreased in UA-treated MSCs. Our data demonstrated that priming MSCs with UA augment neuroprotective properties through enhanced self-renewal and differentiation potential, suggesting a practical strategy for improving the application of MSCs in parkinsonian disorders.

Mesenchymal stem cells modulate misfolded α-synuclein in parkinsonian disorders: A multitarget disease-modifying strategy.

α-Synuclein (α-Syn) aggregates, the major toxic component of Lewy bodies, are proteinaceous fibrillar cytoplasmic inclusions observed in α-synucleinopathies, such as Parkinson's disease (PD), multiple system atrophy, and dementia with Lewy bodies. Overexpression of α-syn induce neuronal loss and α-syn aggregation in PD animals. Recent studies show that α-syn is released by exocytosis and can be transmitted between brain areas through cell-to-cell propagation. Moreover, aggregates of extracellular α-syn can induce neuroinflammation-mediated neurotoxic signaling through microglial activation and release of pro-inflammatory factors. Thus, modulation of α-syn might be a potential therapeutic strategy for modifying disease progression of α-synucleinopathies. Our previous studies have revealed that MSCs have potent neuroprotective effects in PD animal through modulation of neuroinflammation, inhibition of cell death, and promotion of neurogenesis. Here, we provide further evidence that MSCs have the potential to modulate α-syn-related microenvironments via enhancement of autophagy, proteolysis of α-syn aggregates, inhibition of cell-to-cell transmission of α-syn, stabilization of axonal transport, and phagocytic clearance of α-syn by microglial M2 polarization. With advantages in clinical applications, these data suggests that the use of MSCs as pharmacological modulators of α-syn propagation would be an effective therapeutic approach in PD.

Feasibility and Efficacy of Intra-Arterial Administration of Embryonic Stem Cell Derived-Mesenchymal Stem Cells in Animal Model of Alzheimer's Disease.

Mesenchymal stem cells (MSCs) promote functional recoveries in pathological experimental models of the central nervous system and are currently being tested in clinical trials for neurological disorders. However, no studies have examined the various roles of embryonic stem cell derived (ES)-MSCs in eliciting therapeutic effects for Alzheimer's disease (AD). In the present study, we investigated the neuroprotective effect of ES-MSCs in cellular and animal models of AD, as well as the safety of the intra-arterial administration of ES-MSCs in an AD animal model. ES-MSCs displayed higher cell viability than that of bone marrow (BM)-MSCs in amyloid-ß (Aß)-induced cellular models. Moreover, the efficacy of autophagy induction in ES-MSCs was comparable to that of BM-MSCs; however, intracellular Aß levels were more significantly reduced in ES-MSCs than in BM-MSCs. In a rat model of AD, ES-MSCs significantly inhibited Aß-induced cell death in the hippocampus and promoted autophagolysosomal clearance of Aß, which was concomitantly followed by decreased levels of Aß in the hippocampus. Furthermore, ES-MSC treatment in Aß-treated rats featured a higher memory performance than that of rats injected solely with Aß. Finally, intra-arterial administration of an appropriate cell density of ES-MSCs was safe and free from in situ occlusion or cerebral ischemia. These data support the therapeutic potential of ES-MSCs and clinical applications of the intra-arterial route of ES-MSC administration in AD.

Protective effect and mechanism of action of diallyl disulfide against acetaminophen-induced acute hepatotoxicity.

The aim of this study was to investigate the potential protective effects of diallyl disulfide (DADS) against acetaminophen (AAP)-induced acute hepatotoxicity and elucidate the molecular mechanisms underlying these protective effects in rats. Treatment with AAP caused acute hepatotoxicity manifested by elevated levels of aspartate aminotransferase and alanine aminotransferase with corresponding histopathological changes and high levels of oxidative stress in the livers. AAP treatment also caused hepatocellular apoptosis with phosphorylation of c-Jun-N-terminal protein kinase (JNK). In addition, AAP caused activation of nuclear factor kappaB (NF-κB) concurrent with induction of inflammatory mediators. In contrast, pretreatment with DADS effectively attenuated acute liver injury and oxidative stress caused by AAP. DADS pretreatment suppressed cytochrome P450 2E1 (CYP2E1) levels in a dose-dependent manner and inhibited elevation of CYP2E1 activity induced by AAP. DADS pretreatment suppressed the phosphorylation of JNK and attenuated hepatocellular apoptotic changes. In addition, DADS inhibited the nuclear translocation of NF-κB and subsequent induction of inflammatory mediators. Overall, these results indicate that DADS confers a protective effect against oxidative stress-mediated JNK activation and apoptotic changes caused by AAP in the rat livers. This may be due to its ability to inhibit CYP2E1, enhance antioxidant enzymes activities, and suppress NF-κB activation.

Preparation of functional chitosan-based nanocomposite films containing ZnS nanoparticles.

In this study, nanocomposite films were synthesized by chitosan (CH), PVA, ZnS, sulfosuccinic acid, and plasticizers. The nanocomposite films were cross-linked by the heat curing process. ZnS was synthesized by the reaction of Zn(CH3COO)2 and Na2S2O3·5H2O in aqueous solution via a template-free hydrothermal process. The prepared ZnS and CH/PVA nanocomposite films were characterized by X-ray diffraction, Fourier transform IR spectroscopy, and scanning electronic microscopy. The results of this study confirmed the presence of specific peaks of ZnS in the prepared nanocomposite films, and the intensity of these peaks increased with increasing ZnS contents. Tensile strength, elongation at break, water barrier properties, and thermal properties of the prepared nanocomposite films were also investigated, indicating that the addition of ZnS nanoparticles improved the physical and thermal properties. In addition, the photocatalytic degradability of the prepared films containing ZnS nanoparticles was evaluated using 2,4-dichlorophenoxyacetic acid and methyl orange.

Mesenchymal Stem Cells Stabilize Axonal Transports for Autophagic Clearance of α-Synuclein in Parkinsonian Models.

Genome-wide association studies have identified two loci, SNCA and the microtubule (MT)-associated protein tau, as common risk factors for Parkinson's disease (PD). Specifically, α-synuclein directly destabilizes MT via tau phosphorylation and induces axonal transport deficits that are the primary events leading to an abnormal accumulation of α-synuclein that causes nigral dopaminergic cell loss. In this study, we demonstrated that mesenchymal stem cells (MSCs) could modulate cytoskeletal networks and trafficking to exert neuroprotective properties in wild-type or A53T α-synuclein overexpressing cells and mice. Moreover, we found that eukaryotic elongation factor 1A-2, a soluble factor derived from MSCs, stabilized MT assembly by decreasing calcium/calmodulin-dependent tau phosphorylation and induced autophagolysosome fusion, which was accompanied by an increase in the axonal motor proteins and increased neuronal survival. Our data suggest that MSCs have beneficial effects on axonal transports via MT stability by controlling α-synuclein-induced tau phosphorylation, indicating that MSCs may exert a protective role in the early stages of axonal transport defects in α-synucleinopathies. Stem Cells 2017;35:1934-1947.

The Association Between Shift Work and Health Behavior: Findings from the Korean National Health and Nutrition Examination Survey.

BACKGROUND: Shift workers are increasing worldwide, and various negative health effects of shift work have been reported. This study aimed to evaluate the relationship between shift work and health behavior. METHODS: This cross-sectional study included a total of 11,680 Korean adults (6,061 men and 5,619 women) aged ≥20 years old who participated in the Fifth Korean National Health and Nutrition Examination Survey, 2010-2012. Multiple logistic regression analysis was performed to evaluate the association between shift work and health behavior after adjusting for covariates. RESULTS: In men, shift work was associated with an increased risk of inadequate sleep (odds ratio [OR], 1.18; 95% confidence interval [CI], 1.00 to 1.40) compared to day work. In women, shift work was associated with an increased risk of smoking (OR, 1.73; 95% CI, 1.34 to 2.22) and inadequate sleep (OR, 1.24; 95% CI, 1.05 to 1.47) compared to day work. In an age-stratified subgroup analysis, female shift workers aged ≥50 years old demonstrated an increased risk of smoking (OR, 5.55; 95% CI, 3.60 to 8.55), alcohol consumption (OR, 2.22; 95% CI, 1.53 to 3.23), and inadequate sleep (OR, 1.50; 95% CI, 1.10 to 2.05) compared to female day workers. CONCLUSION: Shift work is associated with worse health behavior, and this is most evident in women aged ≥50 years. Targeted strategies to reduce the negative health effects of shift work should be implemented, with consideration of shift workers' demographic characteristics.

The Cleavage Effect of Mesenchymal Stem Cell and Its Derived Matrix Metalloproteinase-2 on Extracellular α-Synuclein Aggregates in Parkinsonian Models.

Ample evidence has suggested that extracellular α-synuclein aggregates would play key roles in the pathogenesis and progression of Parkinsonian disorders (PDs). In the present study, we investigated whether mesenchymal stem cells (MSCs) and their derived soluble factors could exert neuroprotective effects via proteolysis of extracellular α-synuclein. When preformed α-synuclein aggregates were incubated with MSC-conditioned medium, α-synuclein aggregates were disassembled, and insoluble and oligomeric forms of α-synuclein were markedly decreased, thus leading to a significant increase in neuronal viability. In an animal study, MSC or MSC-conditioned medium treatment decreased the expression of α-synuclein oligomers and the induction of pathogenic α-synuclein with an attenuation of apoptotic cell death signaling. Furthermore, we identified that matrix metalloproteinase-2 (MMP-2), a soluble factor derived from MSCs, played an important role in the degradation of extracellular α-synuclein. Our data demonstrated that MSCs and their derived MMP-2 exert neuroprotective properties through proteolysis of aggregated α-synuclein in PD-related microenvironments. Stem Cells Translational Medicine 2017;6:949-961.

Protective effects of diallyl disulfide against acetaminophen-induced nephrotoxicity: A possible role of CYP2E1 and NF-κB.

Diallyl disulfide (DADS) is a degradation product of allicin which is contained in garlic. This study investigated the protective effects of DADS against acetaminophen (AAP)-induced nephrotoxicity and the molecular mechanisms of nephroprotective effects in rats. AAP caused severe nephrotoxicity as evidenced by significant increases in renal tubular cell apoptosis, mitochondria-mediated apoptosis, and up-regulation of nuclear transcription factor kappa-B (NF-κB), cyclooxygenase-2 (Cox-2), and tumor necrosis factor-α (TNF-α) in the kidney with histopathological alterations. After AAP administration, glutathione content and activities of catalase, superoxide dismutase, and glutathione reductase were significantly decreased whereas malondialdehyde content was significantly increased, indicating that AAP-induced kidney injury was mediated through oxidative stress. In contrast, DADS pretreatment significantly attenuated AAP-induced nephrotoxic effects, including oxidative damage, histopathological lesions, and apoptotic changes in the kidney. DADS also attenuated AAP-induced up-regulation of NF-κB, Cox-2, and TNF-α in the kidney, and microsomal CYP2E1 expression in liver and kidney. These results indicated that DADS could prevent AAP-induced nephrotoxicity. The protective effects of DADS might be due to its ability to decrease metabolic activation of AAP by inhibiting CYP2E1 and its potent antioxidant, antiapoptotic, and antiinflammatory effects via inhibition of NF-κB.

Factors associated with alcohol drinking behavior of cancer survivors: The Korean National Health and Nutrition Examination Survey.

BACKGROUND: This study aimed to evaluate the factors associated with drinking behavior of cancer survivors after cancer diagnosis. METHODS: The study subjects were 906 adult cancer survivors who had reportedly drunk alcohol before cancer diagnosis and participated in the Korean National Health and Nutrition Examination Surveys conducted from 2007 to 2013. Among them, 360 abstained from alcohol drinking after cancer diagnosis. We categorized remaining 546 persistent drinkers into high-risk drinker (consuming≥7 glasses of alcohol for men and≥5 glasses of alcohol for women at one sitting at the frequency of at least once a month) or moderate drinker. We used multiple logistic regression analysis to evaluate risk factors associated with drinking behavior. RESULTS: The high-risk drinkers occupied 27.1% (148 survivors) of the persistent alcohol drinking survivors. Age increase (OR=0.96; 95% CI 0.93-0.99), female sex (OR=0.15; 95% CI 0.08-0.28), and increase of time lapse (by 1-year) after cancer diagnosis (OR=0.94; 95% CI 0.92-0.97) were associated with a lower risk of high-risk drinking as compared with moderate drinking. Meanwhile,≤9years of education (OR=1.99; 95% CI 1.10-3.60), alcohol-related cancer (OR=2.09; 95% CI 1.23-3.56), and current smoking (OR=1.92; 95% CI 1.03-3.59) were associated with increased risk of high-risk drinking of cancer survivors. CONCLUSIONS: These findings suggest that greater efforts for preventing high-risk drinking should be laid on the cancer survivors, with consideration of individual sociodemographic characteristics, especially when the survivors had been diagnosed with alcohol-related cancer.

Risk of Cardiovascular Disease Using Framingham Risk Score in Korean Cancer Survivors.

BACKGROUND: Cardiovascular disease is an important cause of morbidity and mortality in cancer survivors. The aim of this study was to investigate the modifiable cardiovascular disease risk factors and 10-year probability of the disease based on the Framingham risk score in cancer survivors, compared with the general population. METHODS: A total of 1,225 cancer survivors and 5,196 non-cancer controls who participated in the 2007-2013 Korea National Health and Nutrition Examination Surveys were enrolled. We assessed modifiable cardiovascular disease risk factors including smoking, body mass index, physical inactivity, high blood pressure, high cholesterol, and elevated blood glucose level. The 10-year probability of cardiovascular disease was determined by applying the Framingham cardiovascular disease risk equation among cancer survivors and non-cancer controls, ranging from 30 to 74 years old who had no overt cardiovascular diseases. RESULTS: The proportion of subjects who had higher fasting glucose levels, hemoglobin A1c levels, systolic blood pressure, and low density lipoprotein cholesterol levels, and those who had lower high density lipoprotein cholesterol levels was significantly higher in the cancer survivors than in the non-cancer controls. The average 10-year probability of cardiovascular disease among the cancer survivors was higher than that in the non-cancer controls in both men and women. The average 10-year probability of cardiovascular disease in relation to the cancer type was significantly higher in patients with hepatic, colon, lung, breast, and gastric cancer. CONCLUSION: Cancer survivors have a higher cardiovascular disease risk and 10-year probability of cardiovascular disease than non-cancer controls. Control of cardiovascular disease risk factors and implementation of a well-defined cardiovascular disease prevention program are needed for treating cancer survivors.

Antioxidant and Hepatoprotective Effects of Procyanidins from Wild Grape (Vitis amurensis) Seeds in Ethanol-Induced Cells and Rats.

In the present study, we characterized the antioxidant and hepatoprotective mechanisms underlying of wild grape seed procyanidins (WGP) against oxidative stress damage in ethanol-treated HepG2 cell and Sprague-Dawley (SD)-rat models. In HepG2 cells, WGP not only diminished the ethanol (EtOH, 100 mM)-induced reactive oxygen species (ROS) formation and cytochrome P450 2E1 (CYP2E1) expression, but also renovated both the activity and expression of antioxidant enzymes including catalase, superoxide dismutase, and glutathione peroxidase. Additionally, to investigate the hepatoprotective effect of WGP, rats were orally administered 10 or 50 mg/kg WGP once daily for seven days prior to the single oral administration of EtOH (6 g/kg). The results show that WGP administration decreased the EtOH-induced augment of the levels of serum aspartate transaminase and alanine transaminase as well as serum alcohol and acetaldehyde. WGP treatment upregulated the activities and protein levels of hepatic alcohol dehydrogenase, aldehyde dehydrogenase, and antioxidant enzymes but downregulated the protein expression level of liver CYP2E1 in EtOH-treated rats. Moreover, the decreased phosphorylation levels of mitogen activated protein kinases (MAPKs) by ethanol were induced in both HepG2 cell and rat models. Overall, pretreatment of WGP displayed the protective activity against EtOH-mediated toxicity through the regulation of antioxidant enzymes and alcohol metabolism systems via MAPKs pathways.

Thiopurine Prodrugs Mediate Immunosuppressive Effects by Interfering with Rac1 Protein Function.

6-Thiopurine (6-TP) prodrugs include 6-thioguanine and azathioprine. Both are widely used to treat autoimmune disorders and certain cancers. This study showed that a 6-thioguanosine triphosphate (6-TGTP), converted in T-cells from 6-TP, targets Rac1 to form a disulfide adduct between 6-TGTP and the redox-sensitive GXXXXGK(S/T)C motif of Rac1. This study also showed that, despite the conservation of the catalytic activity of RhoGAP (Rho-specific GAP) on the 6-TGTP-Rac1 adduct to produce the biologically inactive 6-thioguanosine diphosphate (6-TGDP)-Rac1 adduct, RhoGEF (Rho-specific GEF) cannot exchange the 6-TGDP adducted on Rac1 with free guanine nucleotide. The biologically inactive 6-TGDP-Rac1 adduct accumulates in cells because of the ongoing combined actions of RhoGEF and RhoGAP. Because other Rho GTPases, such as RhoA and Cdc42, also possess the GXXXXGK(S/T)C motif, the proposed mechanism for the inactivation of Rac1 also applies to RhoA and Cdc42. However, previous studies have shown that CD3/CD28-stimulated T-cells contain more activated Rac1 than other Rho GTPases such as RhoA and Cdc42. Accordingly, Rac1 is the main target of 6-TP in activated T-cells. This explains the T-cell-specific Rac1-targeting therapeutic action of 6-TP that suppresses the immune response. This proposed mechanism for the action of 6-TP on Rac1 performs a critical role in demonstrating the capability to design a Rac1-targeting chemotherapeutic agent(s) for autoimmune disorders. Nevertheless, the results also suggest that the targeting action of other Rho GTPases in other organ cells, such as RhoA in vascular cells, may be linked to cytotoxicities because RhoA plays a key role in vasculature functions.