Deoxynucleotidyl Transferase-mediated dUTP-biotin Nick End Research Articles

Up-regulation of glucose regulated protein 78 induced by 2-deoxyglucose plays a protective role for fetal rat cerebral neuron following intrauterine distress

To evaluate the influence of up-regulation of glucose regulated protein 78 (GRP 78) induced by 2-deoxyglucose (2DG) on fetal rat cerebral neuron apoptosis following intrauterine distress and the unification of endoplasmic reticulum and mitochondrium. (1) Fetal rat intrauterine distress model was established and rats were divided into normal group (N = 10), ischemia- reperfusion(IR) group (n = 40) and treatment group (n = 40, injection of 2DG into pregnant rats' abdomen after operation ). (2) Neuron apoptosis and the influence of 2DG on apoptosis was detected by terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end labeling (TUNEL) staining. The expression of GRP78, caspase-9, -12, and cytoron C protein were detected by western blot technique. (1) The number of TUNEL positive neuron in normal group was 4.3 +/- 1.8/mm2. The expression of GRP78, caspase-9, -12, cytoron C in cytoplasm were 0.012 +/- 0.003, 0.004 +/- 0.003, 0.006 +/- 0.002, 0.012 +/- 0.005, respectively. (2) The number of TUNEL positive neuron in the IR group were 43.6 +/- 11.4/mm2 (reperfusion 3 h), 64.4 +/- 9.3/mm2 (reperfusion 6 h), 74.2 +/- 12.1/mm2 (reperfusion 12 h), 97.3 +/- 8.9/ mm2 (reperfusion 24 h), respectively. They were significantly more than that in normal group (P < 0.05). The expression of GRP78 at corresponding times in IR group were 0.092 +/- 0.008 (reperfusion 3 h), 0.078 +/- 0.006 (reperfusion 6 h), 0.054 +/- 0.009 (reperfusion 12 h), 0.038 +/- 0.007 (reperfusion 24 h), respectively. The expression of cytoron C in cytoplasm at corresponding times in IR group were 0.040 +/- 0.006 (reperfusion 3 h), 0.076 +/- 0.009 (reperfusion 6 h), 0.108 +/- 0.005 (reperfusion 12 h), 0.089 +/- 0.008 (reperfusion 24 h), respectively. The expression of caspase-9 at corresponding times in IR group were 0.042 +/- 0.003 ( reperfusion 3 h), 0.086 +/- 0.007 (reperfusion 6 h), 0.142 +/- 0.006 (reperfusion 12 h), 0.112 +/- 0.009 (reperfusion 24 h), respectively. The expression of caspase-12 at corresponding times in IR group were 0.076 +/- 0.006 (reperfusion 3 h), 0.113 +/- 0.010 (reperfusion 6 h), 0.125 +/- 0.005 (reperfusion 12 h), 0.057 +/- 0.008 (reperfusion 24 h), respectively. They were significantly higher than that in normal group (P < 0.05). (3) The number of TUNEL positive neuron in the treatment group were 19.4 +/- 10.6/mm2 (reperfusion 3 h), 26.4 +/- 12.3 /mm2 (reperfusion 6 h), 39.3 +/- 13.3/mm2 (reperfusion 12 h), 49.3 +/- 13.6/mm2 (reperfusion 24 h), respectively. They were significantly lower than that in IR group, but more than that in normal group (P < 0.05). The expression of GRP78 at corresponding times in the treatment group were 0.158 +/- 0.012 (reperfusion 3 h), 0.175 +/- 0.005 (reperfusion 6 h), 0.125 +/- 0.013 (reperfusion 12 h), 0.079 +/- 0.004 (reperfusion 24 h), respectively. They were significantly higher than that in IR group and normal group (P < 0.05) . The expression of cytoron C in cytoplasm at corresponding times in IR group were 0.026 +/- 0.002 (reperfusion 3 h), 0.042 +/- 0.008 (reperfusion 6 h), 0.062 +/- 0.007 (reperfusion 12 h), 0.045 +/- 0.004 (reperfusion 24 h), respectively. The expression of caspase-9 at corresponding times in IR group were 0.033 +/- 0.002 (reperfusion 3 h), 0.063 +/- 0.005 (reperfusion 6 h), 0.092 +/- 0.005 (reperfusion 12 h), 0.068 +/- 0.008 (reperfusion 24 h), respectively. The expression of caspase-12 at corresponding times in IR group were 0.061 +/- 0.004 (reperfusion 3 h), 0.068 +/- 0.009 (reperfusion 6 h), 0.072 +/- 0.007 (reperfusion 12 h), 0.054 +/- 0.005 (reperfusion 24 h), respectively. They were significantly lower than that in IR group, but higher than that in normal group (P < 0.05). Fetal rat cerebral neuron apoptosis following intrauterine distress is associated with the action of endoplasmic reticulum and mitochondrium. Up-regulation of GRP78 induced by 2DG counteracts primary cellular damage caused by endoplasmic reticulum stress. 2DG plays a protective role for fetal rat cerebral neuron following intrauterine distress.

Antithrombin prevents reperfusion-induced hepatic apoptosis by enhancing insulin-like growth factor-I production in mice

Antithrombin (AT) reduces ischemia/reperfusion-induced liver injury by increasing release of calcitonin gene-related peptide (CGRP) from sensory neurons. Because CGRP increases the production of insulin-like growth factor-I (IGF-I), an antiapoptotic factor, it is possible that AT prevents apoptosis by increasing IGF-I production. We examined this possibility in the present study. Prospective, randomized, controlled study. University laboratory. Male C57BL/6 wild-type mice and alphaCGRP-deficient mice weighing 16-23 g. AT (250 units/kg) was intravenously administered to mice subjected to hepatic ischemia/reperfusion. Liver injury was evaluated by determining changes in serum levels of alanine aminotransferase after ischemia/reperfusion. Hepatic apoptosis was detected by terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling staining. AT reduced ischemia/reperfusion-induced liver injury and enhanced increases in hepatic tissue levels of IGF-I in wild-type mice, although it did not reduce liver injury or enhance increases in hepatic tissue levels of IGF-I in alphaCGRP-deficient mice. Reperfusion-induced hepatic apoptosis was markedly suppressed by AT in wild-type mice, but not in alphaCGRP-deficient mice. Pretreatment with anti-IGF-I antibody completely reversed therapeutic effects of AT in wild-type mice. Both CGRP and IGF-I showed therapeutic effects similar to those of AT in wild-type and alphaCGRP-deficient mice. : These observations suggested that AT may prevent reperfusion-induced hepatic apoptosis by enhancing IGF-I production through promotion of sensory neuron activation, thereby reducing ischemia/reperfusion-induced liver injury.

Overexpression of Angiotensin II type 2 receptor (AT2R) in neonatal cardiomyocytes induces apoptosis

In vitro experiments suggest that AT2R is involved in apoptosis of fibroblasts, neurons, and endothelial cells. These apoptotic effects are elicited by either Ang II stimulation or constitutive activation of the AT2 receptor. However, the apoptotic effects of AT2R in cardiomyocytes have not been elucidated. Therefore, we investigated the effects of AT2R overexpression in neonatal rat cardiomyocytes. Neonatal cardiomyocytes were isolated from 5‐day old SD rat pups. An AT2R recombinant adenovirus, Ad5‐CMV‐AT2R‐EGFP, was used to overexpress AT2R. At 48 hours post transduction, apoptosis was evaluated by a deoxynucleotidyltransferase‐mediated dUTP‐biotin nick end labeling (TUNEL) assay (for in situ detection of apoptotic cells). Apoptosis was quantified by percentage of positive TUNEL stained area using ImageJ software. Apoptosis was significantly higher in the AT2R overexpressed cardiomyocytes (2.24 %) compared to both PBS (0.46%) and GFP (0.32%) control groups (P&lt;0.001). A decrease in cell density was evident only in the AT2R overexpressed group after 96 hours of viral transduction compared to the PBS and GFP control groups. We conclude that this decrease in cardiac myocyte density is likely due to constitutive pro‐apoptotic signaling via the AT2R.

Role of epidermal growth factor receptor in maintaining airway goblet cell hyperplasia in rats sensitized to allergen

Stimulation of epidermal growth factor receptor (EGFR) induces airway goblet cell hyperplasia, but the role of this molecule in the maintenance of this pathologic change remains uncertain. To determine the mechanisms by which goblet cell hyperplasia is maintained in airway epithelium, we investigated EGFR-induced signalling pathways that lead to both mucin production and antiapoptosis in vitro. We also tested whether the inhibition of EGFR tyrosine kinase speeds reversal of established goblet cell hyperplasia to normal epithelial phenotype in vivo. MUC5AC production was measured by immunoassay, and antiapoptotic responses were determined by Bcl-2 expression and terminal deoxynucleotidyl transferase-mediated dUTP-biotin Nick End Labelling staining using NCI-H292 cells. The effect of an inhibitor of EGFR tyrosine kinase (AG1478) on goblet cell hyperplasia was also determined in rats sensitized with ovalbumin (OVA). MUC5AC was constitutively expressed and few apoptotic cells were observed in NCI-H292 cells under non-stimulated condition. TGF-alpha increased MUC5AC and Bcl-2 expression, an effect that was prevented by inhibitors of EGFR tyrosine kinase (AG1478), MEK (PD98059), and NF-kappaB (CAPE). After the addition of TGF-alpha, AG1478 and an inhibitor of phosphatidylinositol 3 kinase/Akt (LY294002), but not PD98059, induced a marked apoptotic response, which was prevented by the caspase inhibitor Z-VAD fmk. Goblet cell hyperplasia and EGFR expression in airway epithelium were noted in the OVA-sensitized rats. Intratracheal instillation of AG1478 induced apoptosis of goblet cells, reverting the airway epithelium to normal epithelial phenotype. These findings indicate that EGFR plays an important role in the maintenance of goblet cell hyperplasia. We speculate that inhibitors of the EGFR cascade might be an effective therapy of airway remodelling.

Effect of Dopamine Receptor 1 on Apoptosis of Cultured Neonatal Rat Cardiomyocytes in Simulated Ischaemia/Reperfusion

Dopamine receptors exist in many tissues, including rat cardiac tissue. However, the physiological importance of dopamine receptors in the homeostatic regulation of cardiac function is unclear. In this study, a model of ischaemia/reperfusion was established by culturing primary neonatal rat cardiomyocytes in ischaemia-mimetic solution for 2 hr, followed by incubation in normal culture medium for 24 hr. Lactate dehydrogenase activity, superoxide dismutase activity and malondialdehyde content were determined colorimetrically with a spectrophotometer. Apoptotic cell death was assayed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labelling staining and flow cytometry, and morphological alterations were observed with transmission electron microscopy. The intracellular free calcium concentration ([Ca2+]i) was measured by confocal laser scanning microscopy. Finally, the expression of dopamine receptor 1 (DR1), caspase-3, -8 and -9, Fas, Fas ligand and Bcl-2 and the release of cytochrome c were analysed by Western blot. The results showed that DR1 expression was increased markedly during ischaemia/reperfusion. Treatment with 10 microM SKF-38393 (DR1 agonist) significantly increased lactate dehydrogenase activity, decreased superoxide dismutase activity and increased malondialdehyde content in the culture medium. The DR1 agonist promoted the release of cytochrome c, accumulation of [Ca2+]i, and apoptosis induced by ischaemia/reperfusion. Furthermore, SKF-38393 up-regulated the expression of caspase-3, -8 and -9, Fas and Fas ligand, and down-regulated Bcl-2 expression. In contrast, 10 microM SCH-23390 (DR1 antagonist) had no significant effects on the above indicators. In conclusion, DR1 activation is involved in the apoptosis of cultured neonatal rat cardiomyocytes in simulated ischaemia/reperfusion through the mitochondrial and death receptor pathways.

Neuronal apoptosis does not play an important role in human rabies encephalitis

It is generally accepted that there are not prominent features of neuronal cell death in rabies encephalitis. However, Hemachudha and coworkers recently reported widespread apoptosis in the central nervous system of several human rabies cases (BMC Infect Dis 5: 104, 2005). In this study we have evaluated morphological features and markers of neuronal apoptosis in postmortem brain tissue from 12 cases of human rabies who died in four different countries. Histopathological analysis, TUNEL (terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling) staining, and immunostaining for cleaved (activated) caspase-3 were performed on paraffin-embedded tissues from the cerebral cortex, hippocampus, and brainstem, and additional regional areas from one of the cases. We did not find morphological evidence of neuronal apoptosis or TUNEL staining in any of the cases of rabies encephalitis. Similarly, immunostained cleaved caspase-3 was not seen in neurons, but prominent staining was observed in microglial processes. We conclude that neuronal apoptosis does not play an important pathogenetic role in human rabies encephalitis.

A Continued Study on the Stealth Liposomal Topotecan Plus Amlodipine: In Vitro and In Vivo Characterization in Non-Resistant Solid Tumors

We have previously established a type of anti-resistant stealth liposomal topotecan plus amlodipine for overcoming the multi-drug resistance (MDR) in resistant leukemia cells. The objective of the present study was to further characterize it in the diversified non-resistant solid tumors in vitro and in vivo. Stealth liposomal topotecan plus amlodipine was re-prepared and physicochemically characterized. The in vitro drug release assays of topotecan and amlodipine from liposomes were performed using a dialysis method. 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assays were performed in murine sarcoma S180 cells and human breast cancer MCF-7 cells, respectively. Apoptotic percentages of S180 cells were evaluated using flow cytometry. In vivo anti-tumor activity study and terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) analysis were performed in male Institute of Cancer Research (ICR) mice with S180 xenografts. Stealth liposomal topotecan plus amlodipine exhibited high drug encapsulation efficiencies, suitable particle size distribution, negatively charged zeta potential and prolonged release profiles for both topotecan and amlodipine. Amlodipine potentiated the antiproliferative effect and inducing apoptotic effect of topotecan on the tumor cells, exhibiting an additive anti-tumor effect. Stealth liposomal topotecan plus amlodipine showed the optimal anti-tumor activity and inducing apoptotic effect in the in vivo studies. Stealth liposomal topotecan plus amlodipine demonstrated an overt anti-tumor activity in non-resistant solid tumors, suggesting that it deserves further clinical evaluations.

Primary chemoprevention of endometrial hyperplasia with the peroxisome proliferator-activated receptor gamma agonist rosiglitazone in the PTEN heterozygote murine model

PTEN mutations have been implicated in the development of endometrial hyperplasia and subsequent cancer. Peroxisome proliferator-activated receptor gamma (PPAR-gamma) agonists have demonstrated antineoplastic and chemopreventive effects. The purpose of this study was to evaluate the effects of the PPAR-gamma agonist rosiglitazone on both PTEN wild type and PTEN null cell lines and in the PTEN heterozygote((+/-)) murine model. Hec-1-A (PTEN wild type) and Ishikawa (PTEN null) cells were treated with rosiglitazone. Thirty-five female PTEN(+/-) mice were genotyped and placed into one of four groups for treatment for 18 weeks: A) PTEN wild type with 4 mg/kg rosiglitazone, B) PTEN(+/-) mice with vehicle, C) PTEN(+/-) mice with 4 mg/kg rosiglitazone, and D) PTEN(+/-) mice with 8 mg/kg rosiglitazone. Proliferation and apoptosis were measured by bromodeoxyuridine (BrdU) and terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling of DNA fragmentation sites assay. Rosiglitazone caused cell growth inhibition in both Hec-1-A and Ishikawa in a dose-dependent manner (P < 0.02 and P < 0.03, respectively). Rosiglitazone also induced apoptosis in both Hec-1-A (P < .001) and Ishikawa (P < .001) cells in a dose-dependent manner. In the murine model, rosiglitazone decreased proliferation of the endometrial hyperplastic lesions (B vs C; 39.7% vs 9.3% and B vs D; 39.7% vs 4.2%; P < 0.0001) and increased apoptosis of glandular endometrial epithelial cells (B vs C; 2.8% vs 22.4%; P < 0.0001 and B vs D; 2.8% vs 30.2%; P = 0.003). PPAR-gamma agonist rosiglitazone inhibits proliferation and induces apoptosis in both PTEN intact and PTEN null cancer cell lines and in hyperplastic endometrial lesions in the PTEN(+/)(-)murine model.

Chrysotile Asbestos Causes AEC Apoptosis via the Caspase Activation In Vitro and In Vivo

To determine whether alveolar epithelial cell (AEC) apoptosis via caspase activation is involved in asbestos-induced lung injury, we examined apoptosis, caspase-3 and-9 activation using chrysotile asbestos exposure models in vitro and in vivo.Apoptotic cells were assessed in A549 cells with terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) method after 48 hours exposure of chrysotile asbestos (5 to 100 ug/cm2). Asbestos exposure induced a dose-dependent increase of apoptotic cells, and both pretreatment with Z-LEHD-FMK (caspase-3 inhibitor) or Z-DEMK-FMK (caspase-9 inhibitor) significantly suppressed asbestos-induced apoptosis. Expression of cleaved caspase-3 and-9 increased significantly from 18 to at least 48 hours after asbestos exposure. In vivo study, either 1 or 2 mg of chrysotile asbestos were administered into rat lungs intratracheally, and the lungs were obtained 3 days, 1 and 2 weeks, 1, 3 and 6 months after the administration. Asbestos exposure increased the number of apoptotic cells and the activation of cleaved caspase-3 and-9 most at 3 days in a dose dependent manner, and continued to increase them until at least 6 months after asbestos exposure. Apoptotic cells and cleaved caspase-3 and-9 positive cells were mainly observed in AECs. These findings suggest that AEC apoptosis via caspase-3 and-9 activation is involved in asbestos-induced lung injury.

Role of the Angiotensin II Type 2 Receptor in Arterial Remodeling after Wire Injury in Mice

The angiotensin II type 2 (AT2) receptor promotes apoptosis and inhibits cell proliferation. In the present study, we investigated the role of the AT2 receptor in vascular repair and remodeling following severe vascular injury using AT2 knockout (AT2KO) mice. Left femoral arteries of AT2KO mice and wild-type (WT) control mice were injured by a 0.38 mm steel wire inserted from the lumen. Twenty-eight days after the injury, a concentric vascular wall thickening, composed largely of neointima, was noted both in AT2KO and WT mice. The area occupied by the neointima and the cell count within it were not different in the two mouse strains. However, the area of the medial layer and the cell count within it were significantly larger in AT2KO mice than in WT mice. A BrdU incorporation assay showed that the proliferative activity was high in the neointima but it was not different between the strains. On the other hand, apoptosis assessed by terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) was significantly inhibited in the neointima and the media of AT2KO mice compared to the levels in WT mice. However, the number of TUNEL-positive cell was much smaller in the neointima than in the medial layer in both strains. Taken together, these results indicate that AT2 receptors promote the apoptosis of vascular cells but have no net effect on the neointimal cell growth or luminal narrowing after wire injury. The AT2 receptor may be involved in the control of medial layer thickness, at least in part, through medial cell apoptosis.

Intravenous administration of bone marrow stromal cells increases survivin and Bcl-2 protein expression and improves sensorimotor function following ischemia in rats

Intravenous administration of bone marrow stromal cells (MSCs) in animal models with focal cerebral ischemia has been found to be effective in attenuating neuronal damage. We examined whether intravenously transplanted MSCs alters expression of apoptosis-related proteins. Fisher-344 rats were subjected to 90-min middle cerebral artery occlusion (MCAO). The experimental groups were: (I) vehicle group, with intravenous injection of phosphate-buffered saline (PBS) 3h after MCAO; and (II) transplant group, with intravenous injection of MSCs (3x10(6)cells) 3h after MCAO. Neurological function of rats was evaluated using modified neurological severity score (mNSS) and Rotor-rod Motor Test (RMT). Rats were sacrificed on 1st, 3rd and 7th days of MCAO, and coronal brain sections were stained immunohistochemically to identify the apoptosis-related proteins, namely survivin and Bcl-2. We also examined Terminal Deoxynucleotidyl Transferase-Mediated dUTP-biotin Nick End Labeling (TUNEL)-positive cells on 3rd day of MCAO. Functional recovery according to mNSS and RMT was significantly better in the transplant group as compared with the vehicle group (P<0.05). Immunohistochemical analysis revealed significant expression of survivin on 3rd day and Bcl-2 on 1st and 3rd days in the transplant group. The vehicle group displayed significantly more TUNEL-positive cells than the transplant group on 3rd day (P<0.05). These results suggest that intravenous transplantation of MSCs prevents down-regulation of survivin and Bcl-2 preventing apoptosis and cell death in the ischemic brain leading to motor and sensory function recovery.

Chondroitin Sulfate Inhibits the Nuclear Translocation of Nuclear Factor‐κB in Interleukin‐1β‐Stimulated Chondrocytes

Chondroitin sulfate is referred as a symptomatic slow-acting drug for osteoarthritis because it improves articular function, and reduces joint swelling and effusion. In addition, chondroitin sulfate prevents joint space narrowing of the knee. We hypothesized that the anti-inflammatory effect of chondroitin sulfate is associated to a decrease in the activation of mitogen-activated protein kinases (MAPK) and of the transcription factors nuclear factor-kappaB (NF-kappaB) and activator protein-1 (AP-1). Cultured rabbit chondrocytes were stimulated with interleukin-1beta (IL-1beta) in presence of chondroitin sulfate. Nuclear translocation of NF-kappaB and AP-1, and nitrite concentrations (as an index for nitric oxide) was assessed 48 hr later. The effect of chondroitin sulfate on IL-1beta activation of extracellular signal-regulated kinase 1/2 (Erk1/2) and p38MAPK was documented by immunoblot. The effect of chondroitin sulfate on sodium nitroprusside-induced apoptosis was evaluated with the terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labelling assay. Chondroitin sulfate reduced IL-1beta-induced NF-kappaB nuclear translocation, but not AP-1 translocation, it decreased IL-1beta-induced phosphorylation of Erk1/2 and abrogated p38MAPK phosphorylation, but did not prevent IL-1beta-induced increase in nitrite. Finally, chondroitin sulfate decreased nitroprusside-induced apoptosis of the chondrocytes. These results suggest that some of the biological activities of chondroitin sulfate may be associated to the reduction in Erk1/2 and p38MAPK phosphorylation and nuclear transactivation of NF-kappaB.

Structural Abnormalities in Neurons Are Sufficient To Explain the Clinical Disease and Fatal Outcome of Experimental Rabies in Yellow Fluorescent Protein-Expressing Transgenic Mice

Under natural conditions and in some experimental models, rabies virus infection of the central nervous system causes relatively mild histopathological changes, without prominent evidence of neuronal death despite its lethality. In this study, the effects of rabies virus infection on the structure of neurons were investigated with experimentally infected transgenic mice expressing yellow fluorescent protein (YFP) in neuronal subpopulations. Six-week-old mice were inoculated in the hind-limb footpad with the CVS strain of fixed virus or were mock infected with vehicle (phosphate-buffered saline). Brain regions were subsequently examined by light, epifluorescent, and electron microscopy. In moribund CVS-infected mice, histopathological changes were minimal in paraffin-embedded tissue sections, although mild inflammatory changes were present. Terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end labeling and caspase-3 immunostaining showed only a few apoptotic cells in the cerebral cortex and hippocampus. Silver staining demonstrated the preservation of cytoskeletal integrity in the cerebral cortex. However, fluorescence microscopy revealed marked beading and fragmentation of the dendrites and axons of layer V pyramidal neurons in the cerebral cortex, cerebellar mossy fibers, and axons in brainstem tracts. At an earlier time point, when mice displayed hind-limb paralysis, beading was observed in a few axons in the cerebellar commissure. Toluidine blue-stained resin-embedded sections from moribund YFP-expressing animals revealed vacuoles within the perikarya and proximal dendrites of pyramidal neurons in the cerebral cortex and hippocampus. These vacuoles corresponded with swollen mitochondria under electron microscopy. Vacuolation was also observed ultrastructurally in axons and in presynaptic nerve endings. We conclude that the observed structural changes are sufficient to explain the severe clinical disease with a fatal outcome in this experimental model of rabies.

Flagella Facilitate Escape ofSalmonellafrom Oncotic Macrophages

The intracellular parasite Salmonella enterica serovar Typhimurium causes a typhoid-like systemic disease in mice. Whereas the survival of Salmonella in phagocytes is well understood, little has been documented about the exit of intracellular Salmonella from host cells. Here we report that in a population of infected macrophages Salmonella induces "oncosis," an irreversible progression to eukaryotic cell death characterized by swelling of the entire cell body. Oncotic macrophages (OnMphis) are terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end labeling negative and lack actin filaments (F-actin). The plasma membrane of OnMphis filled with bacilli remains impermeable, and intracellular Salmonella bacilli move vigorously using flagella. Eventually, intracellular Salmonella bacilli intermittently exit host cells in a flagellum-dependent manner. These results suggest that induction of macrophage oncosis and intracellular accumulation of flagellated bacilli constitute a strategy whereby Salmonella escapes from host macrophages.

Edaravone neuroprotection effected by suppressing the gene expression of the Fas signal pathway following transient focal ischemia in rats

Preclinical and clinical studies have demonstrated that a free radical scavenger edaravone has neuroprotective effects on ischemic stroke but the underlying mechanism is not fully understood. The aim of this research is to explore the effect of edaravone on the apoptotic process involving the Fas/FasL signaling pathway. Transient focal ischemia in rats was induced for 2 hours by middle cerebral artery occlusion (MCAO). After reperfusion rats were treated i.v. with either edaravone or physiological saline. The expression of Fas-associated death domain protein (FADD), death-associated protein (Daxx) and caspase-8 was examined by immunohistochemistry. The mRNA levels for FADD and Daxx by reverse-transcriptase PCR (RT-PCR) and apoptosis was assessed by terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end labeling (TUNEL). Neurological scores and infarction volumes were also evaluated. Edaravone significantly improved the neurological outcome (p<0.05) and reduced the total infarct volumes (p<0.05), compared with saline control. In addition, edaravone-treatment significantly reduced the number of TUNEL-positive cells (p<0.01), reduced expression levels of FADD, Daxx and caspase-8 immunoreactivity (p <0.05 approximately 0.01), and decreased mRNA levels of FADD and Daxx (p<0.05 approximately 0.01) within the peri-infarct area. We conclude that edaravone may protect ischemic neurons from apoptosis via suppressing the gene expression of the Fas/FasL signaling pathway.

Aquaporin 7 Is a β-Cell Protein and Regulator of Intraislet Glycerol Content and Glycerol Kinase Activity, β-Cell Mass, and Insulin Production and Secretion

To investigate if intracellular glycerol content plays a role in the regulation of insulin secretion in pancreatic beta cells, we studied the expression of the glycerol channels, or aquaglyceroporins, encoded by the aquaporin 3 (Aqp3), Aqp7, and Aqp9 genes in mouse islets. We found expression of Aqp7 only, not that of Aqp3 or Aqp9, in the endocrine pancreas at both the mRNA (by reverse transcription-PCR) and protein (by immunohistochemistry) levels. Immunohistochemistry revealed a complete overlap between insulin and Aqp7 immunostaining in the pancreatic islet. Inactivation of Aqp7 by gene targeting produced viable and healthy mice. Aqp7-/- mice harbored an increased intraislet glycerol concentration with a concomitant increase of the glycerol kinase transcript level and enzyme activity. The islet triglyceride content in the Aqp7-/- mice was also increased compared to that in the Aqp7+/+ mice. Interestingly, Aqp7-/- mice displayed reduced beta-cell mass and insulin content but increased insulin-1 and insulin-2 mRNAs. The reduction of beta-cell mass in Aqp7-/- mice can be explained at least in part by a reduction in cell proliferation through protein kinase C and the c-myc cascade, with a reduction in the transcript levels of these two genes. Concomitantly, there was a decreased rate of apoptosis, as reflected by terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end labeling and caspase 3 and Bax expression in Aqp7-/- mice. Compared with Aqp7+/+ islets, islets isolated from Aqp7-/- mice secreted insulin at a higher rate under basal low-glucose conditions and on exposure to a high (450 mg/dl) glucose concentration. Aqp7-/- mice exhibited normal fasting blood glucose levels but elevated blood insulin levels. Their plasma glucose response to an intraperitoneal (i.p.) glucose tolerance test was normal, but their plasma insulin concentrations were higher than those of wild-type mice during the 2-h test. An i.p. insulin tolerance test showed similar plasma glucose lowering in Aqp7-/- and Aqp7+/+ mice, with no evidence of insulin resistance. In conclusion, we found that pancreatic beta cells express AQP7, which appears to be a key regulator of intraislet glycerol content as well as insulin production and secretion.

Severe Acute Respiratory Syndrome Coronavirus Gene 7 Products Contribute to Virus-Induced Apoptosis

The proteins encoded by gene 7 of the severe acute respiratory syndrome coronavirus (SARS-CoV) have been demonstrated to have proapoptotic activity when expressed from cDNA but appear to be dispensable for virus replication. Recombinant SARS-CoVs bearing deletions in gene 7 were used to assess the contribution of gene 7 to virus replication and apoptosis in several transformed cell lines, as well as to replication and pathogenesis in golden Syrian hamsters. Deletion of gene 7 had no effect on SARS-CoV replication in transformed cell lines, nor did it alter the induction of early apoptosis markers such as annexin V binding and activation of caspase 3. However, viruses with gene 7 disruptions were not as efficient as wild-type virus in inducing DNA fragmentation, as judged by terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end labeling (TUNEL) staining, indicating that the gene 7 products do contribute to virus-induced apoptosis. Disruption of gene 7 did not affect virus replication or morbidity in golden Syrian hamsters, suggesting that the gene 7 products are not required for acute infection in vivo. The data indicate that open reading frames 7a and 7b contribute to but are not solely responsible for the apoptosis seen in SARS-CoV-infected cells.

DNase X Is a Glycosylphosphatidylinositol-anchored Membrane Enzyme That Provides a Barrier to Endocytosis-mediated Transfer of a Foreign Gene

DNase X is the first mammalian DNase to be isolated that is homologous to DNase I. In this study, we have examined its function using a novel monoclonal antibody and showed it to be expressed on the cell surface as a glycosylphosphatidylinositolanchored membrane protein. High level expression was observed in human muscular tissues and in myotubes obtained in vitro from RD rhabdomyosarcoma cells. We observed that RD myotubes incorporated a foreign gene, lacZ, by endocytosis but that expression of the encoded coding product, beta-galactosidase, was strongly inhibited. Overexpression of DNase X inhibited endocytosis-mediated gene transfer, whereas knockdown of DNase X with small interfering RNA had the opposite effect. These results reveal that DNase X provides a cell surface barrier to endocytosis-mediated gene transfer.

Poly(ADP-ribose) polymerase inhibition by cilostazol is implicated in the neuroprotective effect against focal cerebral ischemic infarct in rat

This study shows that cilostazol displayed a potent inhibition of PARP with IC 50 of 883 ± 41 nM in the enzyme assay, and also significantly reversed H 2O 2-evoked elevated PARP activity and reduced NAD + levels in the PC12 cells with improvement of cell viability. In in vivo study, inhibition of PARP activity by cilostazol prevented cerebral ischemic injury induced by 2-h middle cerebral artery occlusion (MCAO) and 24-h reperfusion. The ischemic infarct was significantly reduced in the rats that received cilostazol (30 mg/kg, twice orally) with improvement of neurological function. Moreover, cilostazol treatment significantly decreased the number of terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL)- and poly(ADP-ribose)-positive cells associated with apoptosis-inducing factor (AIF) translocation to the nucleus in the penumbral region. Further, cilostazol significantly reduced myeloperoxidase activity, a marker of neutrophil infiltration. In line with these findings, the OX-42- (a marker of microglia) and TNF-α-positive cells (a marker of proapoptotic protein) were markedly increased in the vehicle samples, both of which were significantly attenuated by treatment with cilostazol. Taken together, these results suggest that neuroprotective potentials of cilostazol against focal cerebral ischemic injury are, at least in part, ascribed to its anti-inflammatory effects and PARP inhibitory activity.

Effect of Pioglitazone, a Peroxisome Proliferator-Activated Receptor Gamma Agonist, on Ischemia-Reperfusion Injury in Rats

Two groups of rats were used to examine the effect of pioglitazone, a peroxisome proliferator-activated receptor γ (PPARγ) agonist, on rat hearts using an in vivo model of ischemia-reperfusion (I/R) to elucidate potential mechanisms. One group was the 30-min reperfusion group, which was further subdivided into sham (n = 5), vehicle (n = 6) and pioglitazone (3 mg·kg^–1, n = 7) treatment groups with 30 min ischemia followed by 30 min reperfusion to detect data related to cardiac function and the area of myocardial infarction. The other group was the 120-min reperfusion group, subdivided into sham (n = 5), vehicle (n = 6), and pioglitazone 0.3 mg·kg^–1 (n = 6), 1 mg·kg^–1 (n = 7) and 3 mg·kg^–1 (n = 6) treatment groups. Immunohistochemistry, in situ hybridization, terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end labeling (TUNEL) and DNA agarose gel electrophoresis were performed to detect apoptosis and expressions of Bax, Bcl-2, caspase 3, MMP-2 and PPARγ protein, and MMP-2 and PPARγ mRNA. We found that, after acute treatment with pioglitazone, the ratio of necrosis to area at risk decreased by 28% (p < 0.01) and that of necrosis to left ventricle was reduced by 32% (p < 0.01), compared with the vehicle group. Heart rate and +dp/dt_max, representing the cardiac systolic function, as well as –dp/dt_max, the indicator of cardiac diastolic function, improved significantly at 1 and 30 min after reperfusion (p < 0.05–0.01). Furthermore, myocardial apoptosis was significantly suppressed by acute treatment with pioglitazone as evidenced by the decreased number of TUNEL-positive myocytes and DNA ladder, enhanced Bcl-2 protein expression, reduced Bax and caspase 3 protein expression in a dose-dependent manner compared with vehicle-treated rats. In addition, acute treatment with pioglitazone dose-dependently increased PPARγ expression and decreased MMP-2 expression at protein and mRNA levels. Our findings demonstrate that a PPARγ agonist may protect the heart from I/R injury. The protective effect is likely to occur by reducing cardiomyocyte apoptosis and inhibiting MMP-2.