There is growing evidence that the accumulation of DNA damage induced by fine particulate matter (PM
) exposure is an underlying mechanism of pulmonary disease onset and progression. However, there ...is a lack of experimental evidence on whether common factors (age, gender) affect PM
induced genomic damage. Here, we assessed the DNA damage potency of PM
using conventional genotoxicity testing in old male and female mice aged 8 and 40 weeks. Mice were intratracheally instilled with diesel exhaust PM
(DEP, NIST SRM 1650b), twice a week for 4 weeks. Exposure to DEP was not associated with an increase in the frequency of micronucleated polychromatic erythrocytes and did not induce a systemic genotoxic effect in the bone marrow. Meanwhile, the results from the comet assay showed a significant increase in DNA damage in DEP exposed mouse lung specimens. The positive relationship between DEP exposure and DNA damage is stronger in the older than in the younger group. Statistical analysis showed that there was a modifying effect of age on the association between PM
exposure and DNA damage. Our results suggest that the age factor should be considered to better understand the cellular adverse effects of PM
.
Ambient particulate matter is a serious risk factor for health outcomes associated with various diseases, including respiratory and cardiovascular diseases. South Korea is one of the Organization for ...Economic Cooperation and Development (OECD) countries with the highest concentration of ambient particulate matter. The purpose of this study is to identify the status of research on particulate matter and associated health effects in South Korea through bibliometric methods. Scientific articles related to particulate matter (PM
10
and PM
2.5
) and their effects on health published during the last two decades (2000–2019) were retrieved using the Scopus database. The total number of publications on PM
10
and health effects was 518, and 197 publications were authored on PM
2.5
and health effects. This number has increased substantially in the last 3 years. The institution and the country that contributed the highest number of publications to ambient particulate matter research were the Seoul National University and the United States, respectively. Publications on the effects of ambient particulates on children, the elderly, or pregnant women accounted for less than 30% of all retrieved publications. Publications on nitrogen oxides (NOx), sulfur oxide (SO
2
), or polycyclic aromatic hydrocarbons (PAHs) accounted for approximately 30% and 20% of health effects-associated publications retrieved from Scopus concerning PM
10
and PM
2.5
research, respectively. Analysis of author keywords showed that mortality, respiratory diseases, cardiovascular disease, and oxidative stress were main research topics on particulate matter and health effects. Our study provides information that can be used to grasp research trends and not covered research topics on health effects of particulate matter in Korea.
Berberine, an herbal alkaloid, has been reported to have a lipid lowering effect by stabilizing hepatic LDLR mRNA in an ERK-dependent manner rather than promoting transcriptional activity. However, ...considering the complexity of interconnected signal pathways in biological processes, it is highly possible that there exist signal pathway(s) other than ERK pathway which contribute to the berberine-induced up-regulation of LDLR. In the present study, we examined possible involvement of other signal pathways in berberine-induced hepatic LDLR up-regulation. As evidenced by RT-PCR, berberine-induced LDLR mRNA expression was inhibited by JNK inhibitor SP600125 pretreatment. Furthermore, we demonstrate that putative c-jun binding site of LDLR promoter is important in berberine-induced LDLR transcription using luciferase assay. The result of EMSA also shows that berberine induces c-jun binding to LDLR promoter and this is decreased by SP600125 pretreatment. The present study demonstrates that berberine increases transcriptional activity of LDLR promoter and this involves JNK pathway.
Calmodulin-dependent protein kinase II (CaMKII) has been proposed to be a therapeutic target for heart failure (HF). However, the cardiac effect of chronic CaMKII inhibition in HF has not been well ...understood. We have tested alterations of Ca(2+) handling, excitation-contraction coupling, and in vivo β-adrenergic regulation in pressure-overload HF mice with CaMKIIδ knockout (KO). HF was produced in wild-type (WT) and KO mice 1 wk after severe thoracic aortic banding (sTAB) with a continuous left ventricle (LV) dilation and reduction of ejection fraction for up to 3 wk postbanding. Cardiac hypertrophy was similar between WT HF and KO HF mice. However, KO HF mice manifested exacerbation of diastolic function and reduction in cardiac reserve to β-adrenergic stimulation. Compared with WT HF, L-type calcium channel current (I(Ca)) density in KO HF LV was decreased without changes in I(Ca) activation and inactivation kinetics, whereas I(Ca) recovery from inactivation was accelerated and Ca(2+)-dependent I(Ca) facilitation, a positive staircase blunted in WT HF, was recovered. However, I(Ca) response to isoproterenol was reduced. KO HF myocytes manifested dramatic decrease in sarcoplasmic reticulum (SR) Ca(2+) leak and slowed cytostolic Ca(2+) concentration decline. Sarcomere shortening was increased, but relaxation was slowed. In addition, an increase in myofilament sensitivity to Ca(2+) and the slow skeletal muscle troponin I-to-cardiac troponin I ratio and interstitial fibrosis and a decrease in Na/Ca exchange function and myocyte apoptosis were observed in KO HF LV. CaMKIIδ KO cannot suppress severe pressure-overload-induced HF. Although cellular contractility is improved, it reduces in vivo cardiac reserve to β-adrenergic regulation and deteriorates diastolic function. Our findings challenge the strategy of CaMKII inhibition in HF.
Particulate matter 2.5 (PM2.5) induces lung injury by increasing the generation of reactive oxygen species (ROS) and inflammation. ROS aggravates NLRP3 inflammasome activation, which activates ...caspase-1, IL-1β, and IL-18 and induces pyroptosis; these factors propagate inflammation. In contrast, treatment with exogenous 8-hydroxydeoxyguanosine (8-OHdG) decreases RAC1 activity and eventually decreases dinucleotide phosphate oxidase (NOX) and ROS generation. To establish modalities that would mitigate PM2.5-induced lung injury, we evaluated whether 8-OHdG decreased PM2.5-induced ROS generation and NLRP3 inflammasome activation in BEAS-2B cells. CCK-8 and lactate dehydrogenase assays were used to determine the treatment concentration. Fluorescence intensity, Western blotting, enzyme-linked immunosorbent assay, and immunoblotting assays were also performed. Treatment with 80 μg/mL PM2.5 increased ROS generation, RAC1 activity, NOX1 expression, NLRP3 inflammasome (NLRP3, ASC, and caspase-1) activity, and IL-1β and IL-18 levels in cells; treatment with 10 μg/mL 8-OHdG significantly attenuated these effects. Furthermore, similar results, such as reduced expression of NOX1, NLRP3, ASC, and caspase-1, were observed in PM2.5-treated BEAS-2B cells when treated with an RAC1 inhibitor. These results show that 8-OHdG mitigates ROS generation and NLRP3 inflammation by inhibiting RAC1 activity and NOX1 expression in respiratory cells exposed to PM2.5.
Emerging evidences about gut-microbial modulation have been accumulated in the treatment of nonalcoholic fatty liver disease (NAFLD). We evaluated the effect of
and
on the NAFLD pathology and explore ...the molecular mechanisms based on multi-omics approaches. Human stool analysis healthy subjects (
= 25) and NAFLD patients (
= 32) was performed to select NAFLD-associated microbiota. Six-week-old male C57BL/6 J mice were fed a normal chow diet (NC), Western diet (WD), and WD with
(BB) or
(BL; 109 CFU/g) for 8 weeks. Liver/body weight ratio, histopathology, serum/tool analysis, 16S rRNA-sequencing, and metabolites were examined and compared. The BB and BL groups showed improved liver histology and function based on liver/body ratios (WD 7.07 ± 0.75, BB 5.27 ± 0.47, and BL 4.86 ± 0.57) and NAFLD activity scores (WD 5.00 ± 0.10, BB 1.89 ± 1.45, and BL 1.90 ± 0.99;
< 0.05). Strain treatment showed ameliorative effects on gut barrier function. Metagenomic analysis showed treatment-specific changes in taxonomic composition. The community was mainly characterized by the significantly higher composition of the
phylum among the NC and probiotic-feeding groups. Similarly, the gut metabolome was modulated by probiotics treatment. In particular, short-chain fatty acids and tryptophan metabolites were reverted to normal levels by probiotics, whereas bile acids were partially normalized to those of the NC group. The analysis of gene expression related to lipid and glucose metabolism as well as the immune response indicated the coordinative regulation of β-oxidation, lipogenesis, and systemic inflammation by probiotic treatment. BB and BL attenuate NAFLD by improving microbiome-associated factors of the gut-liver axis.
Myocyte apoptosis plays an important role in myocardial infarction and cAMP is crucial in the regulation of myocyte apoptosis. Phosphodiesterase-4 (PDE4) inhibitor blocks the hydrolysis of cAMP via ...inhibition of PDE4 and is attractive candidate for novel anti-inflammatory drugs. However, its function in cardiovascular diseases and cardiomyocyte apoptosis is unclear. Therefore, we investigated whether roflumilast, a PDE4 inhibitor, exerts protective effect against NO-induced apoptosis in both of H9c2 cells and neonatal rat cardiomyocytes (NRCMs), focusing on cAMP downstream molecules such as protein kinase A (PKA) and exchange protein directly activated by cAMP (Epac). According to our data, intracellular cAMP was increased by roflumilast treatment in H9c2 cells and NRCMs. Roflumilast inhibited SNP-induced apoptosis and this effect was reversed by PKA specific inhibitor H-89 and KT-5720. In addition, PKA specific activator N6-benzoyladenosine 3′,5-cyclic monophosphate (N6Bz-cAMP) mimicked the effects of roflumilast. CREB phosphorylation by roflumilast was also inhibited by H-89, indicating that roflumilast protects SNP-induced apoptosis via PKA-dependent pathway. Roflumilast increased Epac1/GTP-Rap1 and the protective effect was abolished by Epac1 siRNA transfection, demonstrating that Epac signaling was also involved in this protective response. In support, Epac specific activator 8-(4-chlrorophenylthio)-2′-O-methyladenosine-3′,5′-cyclic monophosphate (8CPT-2Me-cAMP) protected SNP-induced apoptosis. PI3K/Akt inhibitor LY294002 blocked roflumilast-induced Akt phosphorylation and protective effect. Furthermore, inhibition of Epac1 with siRNA had no effect on roflumilast-induced CREB phosphorylation, whereas inhibited Akt phosphorylation, implicating that Akt phosphorylation was regulated by Epac pathway. In addition, it was also observed that rolipram and cilomilast exert similar effects as roflumilast. In summary, our data indicate that roflumilast protects NO-induced apoptosis via both cAMP–PKA/CREB and Epac/Akt-dependent pathway. Our study suggests a possibility of PDE4 inhibitor roflumilast as a potential therapeutic agent against myocardial ischemia/reperfusion (I/R) injury.
RATIONALERecent studies have highlighted important roles of CaMKII in regulating Ca handling and excitation-contraction coupling. However, the cardiac effect of chronic CaMKII inhibition has not been ...well understood.
OBJECTIVEWe have tested the alterations of L-type calcium current (ICa) and cardiac function in CaMKIIδ knockout (KO) mouse left ventricle (LV).
METHODS AND RESULTSWe used the patch-clamp method to record ICa in ventricular myocytes and found that in KO LV, basal ICa was significantly increased without changing the transmural gradient of ICa distribution. Substitution of Ba for Ca showed similar increase in IBa. There was no change in the voltage dependence of ICa activation and inactivation. ICa recovery from inactivation, however, was significantly slowed. In KO LV, the Ca-dependent ICa facilitation (CDF) and ICa response to isoproterenol (ISO) were significantly reduced. However, ISO response was reversed by β2-adrenergic receptor (AR) inhibition. Western blots showed a decrease in β1-AR and an increase in Cav1.2, β2-AR, and Gαi3 protein levels. Ca transient and sarcomere shortening in KO myocytes were unchanged at 1-Hz but reduced at 3-Hz stimulation. Echocardiography in conscious mice revealed an increased basal contractility in KO mice. However, cardiac reserve to work load and β-adrenergic stimulation was reduced. Surprisingly, KO mice showed a reduced heart rate in response to work load or β-adrenergic stimulation.
CONCLUSIONSOur results implicate physiological CaMKII activity in maintaining normal ICa, Ca handling, excitation-contraction coupling, and the in vivo heart function in response to cardiac stress.
Heparin-binding EGF-like growth factor (HB-EGF) is a member of the EGF family that binds to and activates the EGF receptor. Transactivated by angiotensin II, ET-1, and various growth factors in ...cardiomyocytes, HB-EGF is known to induce cardiac hypertrophy via the PI3K-Akt, MAP kinase, and JAK–STAT pathways. However, little is known about the potential involvement of the ERK5 pathway in HB-EGF-induced cardiac hypertrophy. In the present report, we identify and characterize a novel MEK5–ERK5 pathway that is involved in HB-EGF-induced cardiomyocyte hypertrophy. HB-EGF (10
ng/ml) significantly increased
3H-leucine incorporation and atrial natriuretic factor (ANF) mRNA expression in H9c2 cells. In addition, HB-EGF activated a MEK5–ERK5 pathway. Pretreatment with the EGFR inhibitor AG1478 attenuated the activation of ERK5. Blockade of MEK5–ERK5 signaling using MEK5 siRNA reduced the ability of HB-EGF to increase cell size and the expression of ANF mRNA, suggesting the involvement of an EGFR–ERK5 pathway in HB-EGF-induced cardiomyocyte hypertrophy. We further analyzed cyclooxygenase-2 (COX-2). HB-EGF enhanced the expression of COX-2, a response mediated by MEK5–ERK5 signaling, while the COX-2 inhibitor rofecoxib attenuated HB-EGF-induced ANF mRNA expression, suggesting that COX-2 is also associated with HB-EGF-induced cardiomyocyte hypertrophy. It has been known that ERK5 activates the myocyte enhancer factor (MEF) 2 family of transcription factor, we next tested whether activation of MEF2A contributes to HB-EGF-induced COX-2 expression. Inhibition of MEF2A using siRNA attenuated HB-EGF-induced COX-2, ANF expression and cell size. In conclusion, HB-EGF induces cardiomyocyte hypertrophy through an EGFR–ERK5–MEF2A–COX-2 pathway. Our findings will help us to better understand the molecular mechanisms behind HB-EGF-induced cardiomyocyte hypertrophy.
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