Schisandrin B regulates lipid metabolism in subcutaneous adipocytes

Subcutaneous adipocytes in obese subjects have a lower sensitivity to catecholamine-induced lipolysis and a higher sensitivity to insulin anti-lipolytic effects compared to adipocytes in other adipose depots. Therefore, increasing lipolysis in subcutaneous adipocytes coupled with enhanced fatty acid oxidation may be an anti-obesity strategy. Schisandrin B (Sch B) is one of the most abundant active dibenzocyclooctadiene derivatives found in the fruit of Schisandra chinensis which is a commonly prescribed Chinese medicinal herb. We found that Sch B reduced glycerolipid contents in 3T3-L1 adipocytes and subcutaneous adipocytes dissected from DIO mice. Sch B also activated hormone sensitive lipase (HSL) and increased lipolysis in these adipocyte in a protein kinase A-dependent manner. Interestingly, Sch B increased fatty acid oxidation gene expressions in these adipocytes, implying an increase in fatty acid oxidation after treatment. In in vivo model, we found that Sch B increased HSL phosphorylation, reduced glycerolipid levels and increased fatty acid oxidation gene expressions in the subcutaneous adipocytes in the DIO mice. More importantly, Sch B significantly reduced the subcutaneous adipocyte sizes, subcutaneous adipose tissue mass and body weight of the mice. Our study provides scientific evidence to suggest a potential therapeutic function of Sch B or Schisandra chinensis seed containing Sch B in reducing obesity.

Cinnamon induces browning in subcutaneous adipocytes

Browning is the process of increasing the number of brite cells, which helps to increase energy expenditure and reduce obesity. Consumption of natural and non-toxic herbal extracts that possess the browning effect is an attractive anti-obesity strategy. In this study, we examined the browning effect of cinnamon extract. We found that cinnamon extract (CE) induced typical brown adipocyte multiocular phenotype in 3T3-L1 adipocytes. The treatment also increased brown adipocytes markers and reduced white adipocytes markers in the 3T3-L1 adipocytes. In ex vivo studies, we found that CE increased brown adipocytes markers in the subcutaneous adipocytes isolated from db/db mice and diet-induced obesity (DIO) mice. However, CE did not significantly affect UCP1 expression in the adipocytes isolated from perinephric adipose tissue and epididymal adipose tissue. β3-adernergic receptor (β3-AR) antagonist reduced the CE-enhanced UCP1 expression, suggesting an involvement of the β3-AR activity. Oral administration of CE significantly increased UCP1 expression in the subcutaneous adipose tissue in vivo and reduced the body weight of the DIO mice. Taken together, our data suggest that CE has a browning effect in subcutaneous adipocytes. Our study suggests a natural non-toxic herbal remedy to reduce obesity.

MEF2D Mediates the Neuroprotective Effect of Methylene Blue Against Glutamate-Induced Oxidative Damage in HT22 Hippocampal Cells

Methylene blue (MB) can ameliorate behavioral, neurochemical, and neuropathological impairments in animal models of acute and chronic neurodegenerative disorders, but the underlying mechanism remains unclear. Myocyte enhancer factor 2 (MEF2D) is known to promote neuronal survival in several models, and several survival and death signals converge on MEF2D and regulate its activity. Here, we investigated the role of MEF2D in the neuroprotective effect of MB against glutamate-induced toxicity in HT22 neuronal cells. Our results showed that MB, event at less than 100 nM, improved the viability of HT22 cells exposed to 2 mM glutamate. MB attenuated the mitochondrial impairment and quenches the reactive oxygen species (ROS) induced by glutamate. Surprisingly, MB at 50-200 nM did not affect the Nrf2/HO-1 pathway, an important endogenous anti-oxidative system. Further study showed that MB increased the transcription and translation of MEF2D. In addition, MB upregulated the expression of mitochondrial NADH dehydrogenase 6 (ND6) in a MEF2D-dependent manner. Knockdown of MEF2D abolished both MB-medicated increase of ND6 and MB-induced neuroprotection against glutamate-induced toxicity. Moreover, we showed that MB promoted Akt function activity, suppressed GSK-3β activity, and increased MEF2D level in hippocampus of mice and HT22 cells. These findings for the first time demonstrate that MB protects HT22 neuronal cells against glutamate-induced cell death partially via the regulation of MEF2D-associated survival pathway.

ERK/GSK3β signaling is involved in atractylenolide I-induced apoptosis and cell cycle arrest in melanoma cells

Novel agents need to be developed to overcome the limitations of the current melanoma therapeutics. Atractylenolide I (AT-I) is a sesquiterpene compound isolated from atractylodis macrocephalae rhizoma. Previous findings demonstrated that AT-I exhibited cytotoxic action in melanoma cells. However, the molecular mechanisms of AT‑1's anti-melanoma properties remain to be elucidated. In the present study, the cell cycle-arrest and apoptosis-promoting effects as well as the ERK/GSK3β signaling-related mechanism of action of AT-I were examined. B16 melanoma cells were treated with various concentrations of AT-1 (50, 75 and 100 µM) for 48 or 72 h. Cell cycle and apoptosis were analyzed by flow cytometry. Protein expression levels were detected by western blot analysis. AT-I treatment induced G1 phase arrest, which was accompanied by increased p21 and decreased CDK2 protein expression levels. Apoptosis was observed after AT-I treatment for 72 h, which was accompanied by activated caspase‑3 and ‑8. AT-I treatment significantly decreased phospho-ERK, phospho-GSK3β, c-Jun and increased p53 protein expression levels. Lithium chloride (LiCl, 5 mM), a GSK3β inhibitor, treatment alone did not increase the apoptosis of B16 cells, while pretreatment with LiCl markedly reversed AT-I-induced apoptosis. Additionally, AT-I-induced G1 phase arrest was partially reversed by LiCl pretreatment. In conclusion, ERK/GSK3β signaling was involved in the apoptotic and G1 phase arrest effects of AT-I in melanoma cells.

Effect of tacrine-3-caffeic acid, a novel multifunctional anti-Alzheimer's dimer, against oxidative-stress-induced cell death in HT22 hippocampal neurons: involvement of Nrf2/HO-1 pathway

AIMS

Oxidative stress (OS) plays an important role in the pathogenesis of neurodegenerative diseases, including Alzheimer's disease (AD). This study was designed to uncover the cellular and biochemical mechanisms underlying the neuroprotective effects of tacrine-3-caffeic acid (T3CA), a novel promising multifunctional anti-Alzheimer's dimer, against OS-induced neuronal death.

METHODS AND RESULTS

T3CA protected HT22 cells against high-concentration-glutamate-induced cell death in time- and concentration-dependent manners and potently attenuated glutamate-induced intracellular reactive oxygen species (ROS) production as well as mitochondrial membrane-potential (ΔΨ) disruption. Besides, T3CA significantly induced nuclear factor erythroid 2-related factor 2 (Nrf2) nuclear translocation and increased its transcriptional activity, which were demonstrated by Western blotting, immunofluorescence, and antioxidant response element (ARE)-luciferase reporter gene assay. Further studies showed that T3CA potently up-regulated heme oxygenase-1 (HO-1), an endogenous antioxidative enzyme and a downstream effector of Nrf2, at both mRNA and protein levels. The neuroprotective effects of T3CA were partially reversed by brusatol, which reduced protein level of Nrf2, or by inhibiting HO-1 with siRNA or ZnPP-IX, a specific inhibitor of HO-1.

CONCLUSIONS

Taken together, these results clearly demonstrate that T3CA protects neurons against OS-induced cell death partially through Nrf2/ARE/HO-1 signaling pathway, which further supports that T3CA might be a promising novel therapeutic agent for OS-associated diseases.

Mortality among benzene-exposed workers in China

A large cohort of 74,828 benzene-exposed and 35,805 nonexposed workers employed between 1972 and 1987 in 12 cities in China was followed to determine mortality from all causes. Benzene-exposed study subjects were employed in a variety of occupations including coating applications, and rubber, chemical, and shoe production. Mortality was slightly increased among workers with greater cumulative exposure to benzene (ptrend < 0.05), but this excess was largely due to cancer deaths (ptrend < 0.01). Deaths due to lymphatic and hematopoietic malignancies (ptrend = 0.01) and lung cancer (ptrend = 0.01) increased with increasing cumulative exposure to benzene. Investigations continue to relate benzene exposure to specific lymphatic and hematopoietic malignancies and other causes of death.

Indirect validation of benzene exposure assessment by association with benzene poisoning

We present a validation study of a quantitative retrospective exposure assessment method used in a follow-up study of workers exposed to benzene. Assessment of exposure to benzene was carried out in 672 factories in 12 cities in China. Historical exposure data were collected for 3179 unique job titles. The basic unit for exposure assessment was a factory/work unit/job title combination over seven periods between 1949 and 1987. A total of 18,435 exposure estimates was developed, using all available historical information, including 8477 monitoring data. Overall, 38% of the estimates were based on benzene monitoring data. The highest time-weighted average exposures were observed for the rubber industry (30.7 ppm) and for rubber glue applicators (52.6 ppm). Because of its recognized link with benzene exposure, the association between a clinical diagnosis of benzene poisoning and benzene exposure was evaluated to validate the assessment method that we used in the cohort study. Our confidence in the assessment method is supported by the observation of a strong positive trend between benzene poisoning and various measures, especially recent intensity of exposure to benzene.

A cohort study of cancer among benzene-exposed workers in China: overall results

A large cohort study of 74,828 benzene-exposed and 35,805 unexposed workers employed between 1972 and 1987 in 12 cities in China were followed to determine mortality from all causes and the incidence of lymphohematopoietic malignancies and other hematologic disorders. Benzene-exposed study subjects were employed in a variety of occupations, including painting, printing, and the manufacture of footwear, paint, and other chemicals. All-cause mortality was similar in the benzene-exposed and unexposed comparison group. Statistically significant excess deaths were noted among benzene-exposed subjects for leukemia (RR = 2.3, 95% CP 1.1-5.0), malignant lymphoma (RR = 4.5, 95% CI: 1.3-28.4), and nonneoplastic diseases of the blood (RR = 95% CP 2.5-infinity), and a marginally significant excess was noted for lung cancer (RR = 1.4, 95% CI: 1.0-2.0). Risk was significantly elevated for the incidence of all lymphohematopoietic malignancies (RR = 2.6, 95% CI: 1.5-5.0), malignant lymphoma (RR = 3.5, 95% CI: 1.2-14.9), and leukemia (RR = 2.6, 95% CI.. 1.3-5.7). Among the leukemia subtypes, only acute myelogenous leukemia (AML) incidence was significantly elevated (RR = 3.1, 95% CI: 1.2-10.7), although nonsignificant excesses were also noted for chronic myelogenous leukemia (CML) (RR = 2.6, 95% CI: 0.7-16.9) and lymphocytic leukemias (RR = 2.8, 95% CI.. 0.5-54.5). Significant excesses were found for aplastic anemia (RR = infinity, 95% CI: 2.2-co) and myelodysplastic syndrome (RR = infinity, 95% CI: 1.7-infinity). Employment in benzene-associated occupations in China is associated with a wide spectrum of myelogenous and lymphocytic malignant diseases and related disorders. Investigations continue to assess the nature of these associations.