Overexpression of Hsp20 prevents endotoxin-induced myocardial dysfunction and apoptosis via inhibition of NF-κB activation

The occurrence of cardiovascular dysfunction in sepsis is associated with a significantly increased mortality rate of 70% to 90% compared with 20% in septic patients without cardiovascular impairment. Thus, rectification or blockade of myocardial depressant factors should partly ameliorate sepsis progression. Heat shock protein 20 (Hsp20) has been shown to enhance myocardial contractile function and protect against doxorubicin-induced cardiotoxicity. To investigate the possible role of Hsp20 in sepsis-mediated cardiac injury, we first examined the expression profiles of five major Hsps in response to lipopolysaccharide (LPS) challenge, and observed that only the expression of Hsp20 was downregulated in LPS-treated myocardium, suggesting that this decrease might be one of the mechanisms contributing to LPS-induced cardiovascular defects. Further studies using loss-of-function and gain-of-function approaches in adult rat cardiomyocytes verified that reduced Hsp20 levels were indeed correlated with the impaired contractile function. In fact, overexpression of Hsp20 significantly enhanced cardiomyocyte contractility upon LPS treatment. Moreover, after administration of LPS (25 μg/g) in vivo, Hsp20 transgenic mice (10-fold overexpression) displayed: 1) an improvement in myocardial function; 2) reduced the degree of cardiac apoptosis; and 3) decreased NF-κB activity, accompanied with reduced myocardial cytokines IL-1β and TNF-α production, compared to the LPS-treated non-transgenic littermate controls. Thus, the increases in Hsp20 levels can protect against LPS-induced cardiac apoptosis and dysfunction, associated with inhibition of NF-κB activity, suggesting that Hsp20 may be a new therapeutic agent for the treatment of sepsis.     

A green tea polyphenol, epigalocatechin-3-gallate, induces apoptosis of human hepatocellular carcinoma, possibly through inhibition of Bcl-2 family proteins

BACKGROUND/AIMS: A major polyphenol of green tea, epigallocatechin-3-gallate (EGCG), has previously been shown to induce cell-cycle arrest and apoptosis in various cancers. However, little is known about its effects on hepatocellular carcinomas (HCCs). METHODS: Four HCC cell lines, HLE, HepG2, HuH-7 and PLC/PRF/5, were treated with EGCG or vehicle. Cell viability was assessed by trypan blue staining and WST-8 assay. Cell-cycle, apoptosis and apoptosis-related proteins in HLE cells were evaluated by flow cytometry and Western blotting. The effect of EGCG was also studied in vivo using a xenograft model. The effect of co-treatment with EGCG and tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) was also assessed. RESULTS: EGCG inhibited the growth of all HCC cell lines at concentrations of 50-100 microg/ml. In HLE cells, EGCG induced apoptosis but not cell-cycle arrest and appears to have down-regulated Bcl-2alpha and Bcl-xl by inactivation of NF-kappaB. Oral administration of EGCG showed similar effects in HLE xenograft tumors. Co-treatment with EGCG and TRAIL synergistically induced apoptosis in HLE cells. CONCLUSIONS: EGCG induced apoptosis in HLE cells, both in vitro and in vivo. Moreover, it enhanced TRAIL-induced apoptosis. Therefore, EGCG treatment may be useful for improving the prognosis of HCCs.     

肝细胞凋亡及凋亡相关基因Caspase-3、Bcl-2在慢性乙型重型肝炎中的作用

目的 探讨肝细胞凋亡及凋亡相关基因Caspase-3、Bcl-2在慢性乙型重型肝炎(慢重肝)发生发展机制中的作用.方法 选择慢重肝肝组织标本68例(慢重肝组),正常肝组织标本20例(对照组).采用原位末端转移酶标记技术(terminaldeoxynucleotidyl transferase-mediated dUTP...     

Expression of the bcl-2 family of pro- and anti-apoptotic genes in multiple myeloma and normal plasma cells: regulation during interleukin-6(IL-6)-induced growth and survival

Aberrant expression of genes regulating apoptosis/survival seems to be essential in the stepwise development of human multiple myeloma (MM). In this paper we have compared the expression of bcl-2 family pro- and anti-apoptotic genes in MM cell lines, primary MM cells and normal plasma cells. The Bcl-2, Mcl-1, Bcl-xL/S, Bcl-w, Bax, Bak, and Bad were shown to be expressed in both malignant and non-neoplastic, normal plasma cells. Quantitative analysis revealed that the malignant phenotype seemed to correlate with an elevated expression of Mcl-1, a decreased expression of Bax and, to a lesser extent, an increased Bcl-2/Bax expression ratio. The possible influence of interleukin-6 (IL-6) in regulating the expression of the bcl-2-related genes was also examined. Using the IL-6-dependent MM cell lines U-1958 and U-266-1970 it was clearly shown that IL-6 deprivation induced cell cycle arrest in both cell lines, whereas apoptosis was only detected in the U-1958 cells. Furthermore, the anti-apoptotic proteins Bcl-2, Mcl-1 and Bcl-xL were down-regulated, while the expression of the pro-apoptotic Bax protein was increased. To conclude, we suggest that the expression pattern of the Bcl-2 family of proteins separates the malignant phenotype of MM from normal plasma cells, and that the protecting effect of IL-6 may be conducted via an altered balance between these proteins.     

Cytokine-induced apoptosis and necrosis are preceded by disruption of the mitochondrial membrane potential (Deltapsi(m)) in pancreatic RINm5F cells: prevention by Bcl-2

The mechanisms of cytokine-induced β-cell death are poorly characterised. In rat insulin-producing RINm5F cells, the combination of interleukin-1β, interferon-γ and tumour necrosis factor- presently induced disruption of the mitochondrial membrane potential (Δψ_m) as demonstrated by reduced JC-1 fluorescence. The reduction of Δψ_m was maximal after 8 h and was preceded by increased formation of reactive oxygen species (ROS), as assessed by dichlorofluorescein-diacetate (DCFH-DA) fluorescence. A nitric oxide synthase-, but not a ROS-inhibitor, prevented cytokine-induced loss of Δψ_m. Overexpression of the anti-apoptotic protein Bcl-2 increased both JC-1 and DCFH-DA fluorescence, which was paralleled by protection against cytokine-induced apoptosis and necrosis. It is concluded that cytokines induce a nitric oxide-dependent disruption of Δψ_m and that this may be a necessary event for both β-cell apoptosis and necrosis. Bcl-2 may prevent β-cell death by counteracting mitochondrial permeability transition.     

TGF-β from the Porcine Intestinal Cell Line IPEC-J2 Induced by Porcine Circovirus 2 Increases the Frequency of Treg Cells via the Activation of ERK (in CD4+ T Cells) and NF-κB (in IPEC-J2)

Porcine circovirus 2 (PCV2) causes immunosuppression. Piglets infected with PCV2 can develop enteritis. Given that the gut is the largest immune organ, however, the response of the gut’s immune system to PCV2 is still unclear. Here, IPEC-J2 cells with different treatments were co-cultured with PBMC or CD4⁺ T cells (Transwell). Flow cytometry and Western blotting revealed that PCV2-infected IPEC-J2 increased the frequency of CD4⁺ T cells among piglets’ peripheral blood mononuclear cells (PBMCs) and caused CD4⁺ T cells to undergo a transformation into Foxp3⁺ regulatory T cells (Treg cells) via activating CD4⁺ T ERK. Cytokines production and an inhibitor assay showed that the induction of Tregs by PCV2-infected IPEC-J2 was dependent on TGF-β induced by PCV2 in IPEC-J2, which was associated with the activation of NF-κB. Taken together, PCV2-infected IPEC-J2 activated NF-κB to stimulate the synthesis of TGF-β, which enhanced the differentiation of CD4⁺ T cells into Treg cells through the activation of ERK in CD4⁺ T cells. This information sheds light on PCV2′s function in the intestinal immune system and suggests a potential immunosuppressive mechanism for PCV2 infection.     

Effect of all‐trans retinoic acid on apoptosis and expression of regulatory genes (Bcl‐2, Fas,ICE) in experimentally induced gastric epithelial cell dysplasia in rats

OBJECTIVE : To study the mechanism and effect of all‐trans retinoic acid on apoptosis and the expression of Bcl‐2, Fas and ICE in experimentally induced dysplastic gastric epithelial cells. METHODS : Apoptosis and expression of Bcl‐2, Fas and ICE in gastric epithelial cells was studied using the terminal dUTP nucleotide end‐labeling (TUNEL) technique. The immunohistochemistry of Wistar rats enrolled in three groups was studied: group 1, blank controls; group 2, dysplasia induced by N‐methyl‐N‐nitro‐N‐nitrosoguanidine (MNNG) and then treated with all‐trans retinoic acid; and group 3, dysplasia induced by MNNG and treated with a placebo. RESULTS : In the three groups, the rates of dysplasia were 0, 26.7 and 73.3%; the apoptosis indices were 8.3 ± 3.1, 7.8 ± 2.6 and 2.2 ± 0.4; the expression of Bcl‐2 was 13.3, 33.3 and 66.7%; and overexpression of Bcl‐2 was 6.7, 6.7 and 33.3%, respectively. There were significant differences between group 2 and group 3 (P < 0.05), but no significant differences were found between group 2 and group 1 (P > 0.05). The expression rates of Fas were 46.7, 40 and 6.7%; the overexpression rates were 13.3, 26.7 and 13.3%, respectively; the expression rates of ICE were 20, 60 and 13.3%; the overexpression rates were 0, 13.3 and 6.7% in the three groups, respectively. The expression rates of Fas and ICE in group 2 were significantly different from that of group 3 (P < 0.05), but there were no significant differences in overexpression rates between group 2 and group 3. No significant differences were found either in expression or overexpression of Fas and ICE between group 2 and group 1. CONCLUSIONS : These results suggest that all‐trans retinoic acid inhibits Bcl‐2 expression, promotes Fas expression, enhances ICE expression and gastric mucosal epithelial cell apoptosis, and thus may reverse or inhibit the progression to cancer.     

Tissue-specific expression and regulation by 1,25(OH)2D3 of chick protein kinase inhibitor (PKI) mRNA

The heat-stable protein kinase inhibitor (PKI) protein is a specific and potent competitive inhibitor of the catalytic subunit of cAMP-dependent protein kinase (PKA). Previously, it has been shown that vitamin D status affects chick kidney PKI activity: a 5- to 10-fold increase in PKI activity was observed in kidneys of chronically vitamin D-deficient chicks and treatment with 1,25-dihydroxyvitamin D₃ (1,25[OH]₂D₃) in cultured kidney cells resulted in a 95% decrease in PKI activity. The authors have recently cloned the cDNA for chick kidney PKI and have used the coding sequence to study the regulation of PKI mRNA. Northern analysis showed the expression of two PKI messages, which are 2.7 and 3.3 kb in size. These mRNAs are expressed in brain, muscle, testis, and kidney, but not in pancreas, liver, or intestine. PKI mRNA steady-state levels are downregulated by 47% in kidneys from vitamin D-replete chicks as compared to vitamin D-deficient chicks. PKI mRNA levels in brain, muscle, and testis are not affected by vitamin D status. Treatment of primary chick kidney cultures treated with 10⁻⁷ M, 1,25(OH)₂D₃ for 24 h resulted in a 20–30% decrease in PKI mRNA. 1,25(OH)₂D₃ treatment does not affect the stability of PKI mRNA as determined by treatment of cell cultures with actinomycin D. This study shows that 1,25(OH)₂D₃ directly and tissue-specifically downregulates PKI mRNA in the chick kidney.     

垂体腺苷酸环化酶激活肽对脑缺氧缺血新生大鼠胱冬酶-3和X-连锁凋亡抑制蛋白表达的影响

目的 观察垂体腺苷酸环化酶激活肽(pituitary adenylate cyclase activating peptide,PACAP)对脑缺氧缺血(hypoxic-ischemic brain damage,HIBD)新生大鼠胱冬酶-3和x-连锁凋亡抑制蛋白(x-linked inhibitor of apoptosis protein,XIAP)的影响,探讨其脑保护作用和有效剂量.方法 60只新生大鼠随机分为假手术组、生理盐水对照组以及PACAP大剂量组(10-8 mol)、中等剂量组(10-9 mol)和小剂量组(10-8 mol),建立HIBD动物模型.应用实时荧光定量聚合酶链反应法榆测新生大鼠HIBD后24 h损伤侧脑组织的胱冬酶-3 mRNA和XIAP mRNA表达情况,应用分光光度法检测胱冬酶-3活性.结果 在HIBD后24 h,生理盐水对照组胱冬酶-3 mRNA表达和酶活性以及XIAP mRNA表达均显著高于假手术组(P均<0.01);PACAP各剂量组胱冬酶-3 mRNA表达和酶活性均显著低于生理盐水对照组(P均<0.01),而XIAP mRNA表达均显著高于牛理盐水对照组(P均<0.01).结论 PACAP能上调XIAP mRNA表达,抑制胱冬酶-3 mRNA表达和酶活性,对新生大鼠HIBD具有保护作用,而且在大剂量、中等剂量和小剂量时均有效.     

1,25(OH)_2D_3对去卵巢大鼠骨组织成骨细胞、骨细胞凋亡的影响

目的观察1,25(OH)_2D_3对去卵巢大鼠骨组织中成骨细胞、骨细胞凋亡的影响。方法 36只雌性SD大鼠随机分成四组,对尼尔雌醇组和1,25(OH)_2D_3组分别给予尼尔雌醇(0.1mg/kg)和1,25(OH)_2D_3(0.05μg/kg)治疗12周。12周后,以DXA法测定大鼠全身的骨密度;放射免疫法测定各组大鼠血清中骨钙素及雌二醇的水平;处死各组大鼠,采用3′-OH末端DNA原位标记技术和透射电镜检测骨细胞、成骨细胞凋亡。结果 12周后,去卵巢组大鼠的骨密度和血清雌二醇水平明显降低,骨钙素含量升高,与假手术组相比,差异有显著性(P0.05)。1,25(OH)_2D_3可以增加去卵巢大鼠的全身骨密度和血清骨钙素含量(P0.05),但是不增加血清雌二醇的水平(P0.05)。1,25(OH)_2D_3可以抑制骨细胞、成骨细胞凋亡,与去卵巢组相比差异有显著性(P0.05)。结论 1,25(OH)_2D_3对去卵巢大鼠骨质疏松症具有防治作用,其部分机制可能为1,25(0H)_2D_3抑制了骨细胞、成骨细胞凋亡,从而调节骨重建。