Ki-Chan Ha

Bax Inhibitor-1 Regulates Endoplasmic Reticulum Stress-associated Reactive Oxygen Species and Heme Oxygenase-1 Expression

The Bax inhibitor-1 (BI-1) is an anti-apoptotic protein that is located in endoplasmic reticulum (ER) membranes and protects cells from ER stress-induced apoptosis. The ER is associated with generation of reactive oxygen species (ROS) through oxidative protein folding. This study examined the role of BI-1 in the regulation of ER stress-induced accumulation of ROS and expression of unfolded protein response-associated proteins. BI-1 reduced the expression levels of glucose response protein 78, C/EBP homologous protein, phospho-eukaryotic initiation factor 2α, IRE1α, XBP-1, and phospho-JNK and inhibited the cleavage of ATF-6α p-90, leading to the inhibition of ROS. Although ROS scavengers offer some protection against ER stress-induced apoptosis, the expression of pro-apoptotic ER stress proteins was not affected. This study shows that the response of unfolded proteins is followed by ROS accumulation under ER stress, which is regulated in BI-1 cells. The mechanism for these BI-1-associated functions involves the expression of heme oxygenase-1 (HO-1) through nuclear factor erythroid 2-related factor 2. In BI-1 cells, the transfection of HO-1 small interfering RNA completely abolished the BI-1-induced protection. The endogenous expression of HO-1 through ER stress-initiated ROS is believed to be as a protection signal. In conclusion, these observations suggest that BI-1 can inhibit the ER stress proteins as well as the accumulation of ROS, thereby protecting the cells. Moreover, HO-1 plays an important role in the BI-1-associated protection against ER stress.

Bax Inhibitor-1 Is a pH-dependent Regulator of Ca2+ Channel Activity in the Endoplasmic Reticulum

In this study, Bax inhibitor-1 (BI-1) overexpression reduces the ER pool of Ca2+ released by thapsigargin. Cells overexpressing BI-1 also showed lower intracellular Ca2+ release induced by the Ca2+ ionophore ionomycin as well as agonists of ryanodine receptors and inositol trisphosphate receptors. In contrast, cells expressing carboxyl-terminal deleted BI-1 (CΔ-BI-1 cells) displayed normal intracellular Ca2+ mobilization. Basal Ca2+ release rates from the ER were higher in BI-1-overexpressing cells than in control or CΔ-BI-1 cells. We determined that the carboxyl-terminal cytosolic region of BI-1 contains a lysine-rich motif (EKDKKKEKK) resembling the pH-sensing domains of ion channels. Acidic conditions triggered more extensive Ca2+ release from ER microsomes from BI-1-overexpressing cells and BI-1-reconsituted liposomes. Acidic conditions also induced BI-1 protein oligomerization. Interestingly subjecting BI-1-overexpressing cells to acidic conditions induced more Bax recruitment to mitochondria, more cytochrome c release from mitochondria, and more cell death. These findings suggest that BI-1 increases Ca2+ leak rates from the ER through a mechanism that is dependent on pH and on the carboxyl-terminal cytosolic region of the BI-1 protein. The findings also reveal a cell death-promoting phenotype for BI-1 that is manifested under low pH conditions.

Kaempferol protects ischemia/reperfusion-induced cardiac damage through the regulation of endoplasmic reticulum stress.

This study examined whether or not the ER stress and Bcl-2 proteins are linked to the protective effect of kaempferol, a phytoestrogen, on ischemia-reperfusion (I/R)-induced cardiac damage. In order to determine if kaempferol modifies the I/R-induced response in H9c2 cardiac muscle cells, the cells were exposed to kaempferol followed by ischemia 12h/reperfusion 4h. kaempferol had a protective effect on the apoptosis induced by I/R in the cardiac muscle cells. The Kaempferol treatment significantly increased the expression level of the anti-apoptotic protein, Bcl-2, but decreased the level of the pro-apoptotic protein, bax. Kaempferol down-regulated the expressions of the endoplasmic reticulum (ER) stress proteins, GRP78, ATF-6alpha, XBP-2, IRE1-alpha, phosphor-eIF-2alpha and CHOP. In ex vivo-Langendorff experiment, the kaempferol treatment regulated the expression of ER stress proteins-CHOP and GRP78. The kaempferol also improved the post-ischemic LVEDP and LVDP significantly after 20, 30, 40 and 50 min of reperfusion compared with the untreated control hearts, which shows that kaempferol offers protection against I/R-associated cardiac dysfunction.

Effects of Ficus carica paste on loperamide-induced constipation in rats.

OBJECTIVE Constipation is one of the most common gastrointestinal complaints worldwide. This study examined the effects of fig (Ficus carica L.) paste for the treatment of loperamide-induced constipation in a rat model. METHODS Animals were divided into one normal control group and four experimental groups (0, 1, 6, and 30 g/kg). Loperamide (2 mg/kg, twice per day) was injected intraperitoneally to induce constipation in the four experimental groups. Fig paste was administered for 4 weeks to assess its anti-constipation effects. RESULTS Fecal pellet number, weight and water content were increased in the fig-treated groups as compared to the control group. Reductions in body weight and increased intestinal transit length were observed in the fig-treated groups. Fecal pellet number was reduced in the distal colons of the fig-treated rats. Exercise and ileum tension increased in the experimental groups as compared to the control group. According to histological analyses, the thickness of the distal colon and areas of crypt epithelial cells that produce mucin were increased in the fig-treated groups in a dose-dependent manner. CONCLUSION Constipation was decreased when fig fruit was fed to rats. Specifically, fecal number, weight, and water content, as well as histological parameters such as thickness and mucin areas in the distal colon were improved. Fig treatment may be a useful therapeutic and preventive strategy for chronic constipation.

Overexpression of junctate induces cardiac hypertrophy and arrhythmia via altered calcium handling

Junctate-1 is a newly identified integral endoplasmic/sarcoplasmic reticulum Ca2+ binding protein. However, its functional role in the heart is unknown. In the present study, the consequences of constitutively overexpressed junctate in cardiomyocytes were investigated using transgenic (TG) mice overexpressing junctate-1. TG mice (8 weeks old) showed cardiac remodeling such as marked bi-atrial enlargement with intra-atrial thrombus and biventricular hypertrophy. The TG mice also showed bradycardia with atrial fibrillation, reduced amplitude and elongated decay time of Ca2+ transients, increased L-type Ca2+ current and prolonged action potential durations. Time-course study (2-8 weeks) showed an initially reduced SR function due to down-regulation of SERCA2 and calsequestrin followed by sarcolemmal protein expression and cardiac hypertrophy at later age. These sequential changes could well be correlated with the physiological changes. Adrenergic agonist treatment and subsequent biochemical study showed that junctate-1 TG mice (8 weeks old) were under local PKA signaling that could cause increased L-type Ca2+ current and reduced SR function. Junctate-1 in the heart is closely linked to the homeostasis of E-C coupling proteins and a sustained increase of junctate-1 expression leads to a severe cardiac remodeling and arrhythmias.

Estrogen attenuates cardiac ischemia-reperfusion injury via inhibition of calpain-mediated bid cleavage

Although several studies have shown that the administration of 17β-estradiol (estrogen) is cardioprotective to ischemia-reperfusion (I/R), the molecular mechanisms are largely unknown. Therefore, we investigated the effects of estrogen on myocardial I/R injury in rat that were sham operated (Sham), ovariectomized (OVX), or ovariectomized and then given estrogen supplementation (OE). Langendorff-perfused rat hearts were subjected to I/R stimuli and the effects of estrogen were examined on cardiac performance. Additionally, we examined the mechanism of estrogen-mediated inhibition of apoptosis. Depression in cardiac contractile function and an increment of calpain activity were observed during I/R in the OVX rats. Estrogen replacement recovered cardiac contractile function and attenuated calpain activity, Bid cleavage, and caspases activities. Throughin vitro assay using cardiomyocytes, we demonstrated that addition of H2O2 (100 μM) significantly increased calpain activity, which was attenuated by estrogen. Moreover, calpain activity was inhibited by calpain inhibitors such as ALLN or leupeptin, but not by caspase-8 inhibitor peptide. These results suggest that estrogen protects the heart against I/R injury through the decrease of calpain activity, Bid cleavage and caspase-8 activity. These apoptotic mechanisms may play a critical role on I/R-associated cardiac damage.

Postprandial glucose-lowering effects of fermented red ginseng in subjects with impaired fasting glucose or type 2 diabetes: a randomized, double-blind, placebo-controlled clinical trial

BackgroundRed ginseng is prepared by steaming raw ginseng, a process believed to increase the pharmacological efficacy. Further bioconversion of red ginseng through fermentation is known to increase its intestinal absorption and bioactivity, and bioconversion diminishes the toxicity of red ginseng’s metabolite. This study was conducted to investigate the effects of daily supplementation with fermented red ginseng (FRG) on glycemic status in subjects with impaired fasting glucose or type 2 diabetes.MethodsThis study was a four-week long, randomized, double-blind, placebo-controlled trial. Forty-two subjects with impaired fasting glucose or type 2 diabetes were randomly allocated to two groups assigned to consume either the placebo or fermented red ginseng (FRG) three times per day for four weeks. Fasting and postprandial glucose profiles during meal tolerance tests were assessed before and after the intervention.ResultsFRG supplementation led to a significant reduction in postprandial glucose levels and led to an increase in postprandial insulin levels compared to the placebo group. There was a consistently significant improvement in the glucose area under the curve (AUC) in the FRG group. However, fasting glucose, insulin, and lipid profiles were not different from the placebo group.ConclusionDaily supplementation with FRG lowered postprandial glucose levels in subjects with impaired fasting glucose or type 2 diabetes.Trial registrationClinicalTrials.gov: NCT01826409

Preventive Effect of Korean Red Ginseng for Acute Respiratory Illness: A Randomized and Double-Blind Clinical Trial

Korean Red Ginseng (KRG) is a functional food and has been well known for keeping good health due to its anti-fatigue and immunomodulating activities. However, there is no data on Korean red ginseng for its preventive activity against acute respiratory illness (ARI). The study was conducted in a randomized, double-blinded, placebo-controlled trial in healthy volunteers (Clinical Trial Number: NCT01478009). Our primary efficacy end point was the number of ARI reported and secondary efficacy end point was severity of symptoms, number of symptoms, and duration of ARI. A total of 100 volunteers were enrolled in the study. Fewer subjects in the KRG group reported contracting at least 1 ARI than in the placebo group (12 [24.5%] vs 22 [44.9%], P = 0.034), the difference was statistically significant between the two groups. The symptom duration of the subjects who experienced the ARI, was similar between the two groups (KRG vs placebo; 5.2 ± 2.3 vs 6.3 ± 5.0, P = 0.475). The symptom scores were low tendency in KRG group (KRG vs placebo; 9.5 ± 4.5 vs 17.6 ± 23.1, P = 0.241). The study suggests that KRG may be effective in protecting subjects from contracting ARI, and may have the tendency to decrease the duration and scores of ARI symptoms.

The Protective Effect of Epigallocatechin-3 Gallate on Ischemia/Reperfusion Injury in Isolated Rat Hearts: An ex vivo Approach

The aim of this study was to evaluate the preventive role of epigallocatechin-3 gallate (EGCG, a derivative of green tea) in ischemia/reperfusion (I/R) injury of isolated rat hearts. It has been suggested that EGCG has beneficial health effects, including prevention of cancer and heart disease, and it is also a potent antioxidant. Rat hearts were subjected to 20 min of normoxia, 20 min of zero-flow ischemia and then 50 min of reperfusion. EGCG was perfused 10 min before ischemia and during the whole reperfusion period. EGCG significantly increased left ventricular developed pressure (LVDP) and increased maximum positive and negative dP/dt (+/-dP/dtmax). EGCG also significantly increased the coronary flow (CF) at baseline before ischemia and at the onset of the reperfusion period. Moreover, EGCG decreased left ventricular end diastolic pressure (LVEDP). This study showed that lipid peroxydation was inhibited and Mn-SOD and catalase expressions were increased in the presence of EGCG. In addition, EGCG increased levels of Bcl-2, Mn-superoxide dismutase (SOD), and catalase expression and decreased levels of Bax and increased the ratio of Bcl-2/Bax in isolated rat hearts. Cleaved caspase-3 was decreased after EGCG treatment. EGCG markedly decreased the infarct size while attenuating the increase in lactate dehydrogenase (LDH) levels in the effluent. In summary, we suggest that EGCG has a protective effect on I/R-associated hemodynamic alteration and injury by acting as an antioxidant and anti-apoptotic agent in one.

Interleukin-6 and Cyclic AMP Stimulate Release of Cathepsin B in Human Osteoblasts

Previous studies have suggested that cathepsin B participates in the joint destruction associated with rheumatoid arthritis (RA). This study examined the activity of cathepsin B (a lysosomal cysteine protease) in human osteoblasts along with its regulation by cyclic AMP and Interleukin-6 (IL-6). Cyclic AMP elevating agents activate cathepsin B and stimulate the secretion of cathepsin B via the secretion of IL-6, a potent mediator of RA. This study investigated the induction of cathepsin B using the proinflammatory cytokine in human osteoblasts (MG-63) in relation to p38 mitogen-activated protein kinase (MAPK) and nuclear factor (NF)-kappa B transcription factor. When added to MG-63 cells, IL-6 stimulated the production of cathepsin B, which was reduced significantly by the addition of SB203580, a specific p38 MAPK inhibitor. In addition, the release of IL-6 was also inhibited by either pyrrolidine dithiocarbamate (PDTC) or NF-κB SN50, which are potent NF-κB inhibitors. Both NF-κB inhibitors had a larger inhibitory effect on the activity of cathepsin B in the presence of SB203580. IL-6 stimulated the NF-κB binding affinity as well as the activation of p38 MAP kinase, leading to the release of cathepsin B. However, SB203580 had no effect on the IL-6-induced activation of NF-κB, and neither of the NF-κB inhibitors decreased the level of p38 MAPK activation in the IL-6-stimulated osteoblasts. Moreover, IL-6 increased the activity of urokinase type plasminogen activator (uPA) in MG-63 cells, which was inhibited by SB203580, PDTC and NF-κB SN50. This strongly suggests that p38 MAPK and NF-κB are essential to the IL-6-induced activation of cathepsin B or uPA and that these two IL-6-activated pathways can act independently.