烧伤血清作用下心肌细胞蛋白激酶B和p38丝裂原活化蛋白激酶通路的交叉对话研究

目的 了解在烧伤血清刺激下大鼠心肌细胞内是否存在磷脂酰肌醇3-激酶(PI3K)/蛋白激酶B(Akt)与p38丝裂原活化蛋白激酶(p38MAPK,以下简称p38)信号通路的交叉对话,探讨此二通路在烧伤后心肌细胞损伤中的作用. 方法建立烧伤血清刺激下的大鼠心肌细胞模型.(1)检测体积分数10%的烧伤血清刺激不同时间后,心肌细胞内磷酸化p38(p-p38)和磷酸化Akt(p-Akt)的表达水平.(2)检测在不同体积分数(5%、10%、20%)的烧伤血清或体积分数10%烧伤血清+胰岛素(1×10-6、1×10-7、1×10-8mol/L)作用下,心肌细胞内p-p38和p-Akt的表达水平,并测定细胞培养上清液中肌酸激酶(CK)的含量.(3)采用p38MAPK通路抑制剂SB203580、PI3K/Akt通路抑制剂LY294002进行阻断实验,测定心肌细胞内p-p38和p-Akt的表达水平及细胞培养上清液中CK的含量. 结果 (1)体积分数10%烧伤血清作用1、3、6、12、24 h时,心肌细胞p-p38水平分别为4.0±0.8、3.6±0.8、5.1±1.6、2.4±0.5、3.0±0.6,较作用0 h时(加入血清后即刻)的水平(1.0)明显增高(P<0.01);而p-Akt表达水平分别为0.15±0.07、0.64±0.10、0.26±0.08、0.38±0.11、0.59±0.13,较作用0 h时水平(1.00)明显降低(P<0.01).(2)不同浓度烧伤血清或烧伤血清+胰岛素作用下,p-p38和p-Akt的表达水平呈相反变化趋势;心肌细胞CK的释放量随烧伤血清浓度升高而增高,胰岛素对此有明显的抑制作用(P<0.05或P<0.01).(3)LY294002能够升高烧伤血清导致的低P-p38水平,抵消胰岛素的保护作用(P<0.01);SB203580能使烧伤血清所致的低p-Akt水平得以回升(P<0.01),抑制烧伤血清引起的CK释放. 结论烧伤血清作用下的心肌细胞存在PI3K/Akt和p38信号通路的交叉对话,并可能对心肌细胞产生调控作用.     

Down‐regulation of mir‐27b promotes angiogenesis and fibroblast activation through activating PI3K/AKT signaling pathway

To study the effects of mir‐27b on angiogenesis and fibroblast activation and to explore its further mechanism. Humanmicrovascular endothelial cell (HMEC)‐1 and humannormal skin fibroblast (BJ) cells were treated with mir‐27b inhibitor negative control reagent, mir‐27b inhibitor, LY294002, and mir‐27b inhibitor + LY294002, respectively. 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide (MTT) was used to detect the T‐cell proliferation. The migration ability was detected by Scratch assays. The angiogenesis of HMEC‐1 cells was observed by in vitro tube formation assay. The mRNA and protein expression of vascular endothelial growth factor (VEGF) in HMEC‐1 cells and the mRNA and protein expression of collagen I, collagen III, α‐SMA, and MMP1 in BJ cells were detected by quantitativereal‐time polymerase chain reaction (qRT‐PCR) and Western blot, respectively. Meanwhile, the PI3K/protein kinase B (AKT) pathway‐related proteins were also detected by Western blot. The proliferation, migration, angiogenesis, the mRNA and protein expression of VEGF and the protein expression of p‐PI3K and p‐AKT in HMEC‐1 cells were increased after treated with mir‐27b inhibitor. Meanwhile, the proliferation, migration, and the protein expression of collagen I, collagen III, α‐SMA, MMP1, p‐PI3K, and p‐AKT in BJ cells were increased after treated with mir‐27b inhibitor. However, the angiogenesis and fibroblast activation of mir‐27b inhibitor was reversed by LY294002, and the activate effect to PI3K/AKT pathway was also inhibited. Down‐regulation of mir‐27b could promote angiogenesis and fibroblast activation, and its mechanism is related to activate PI3K/AKT signaling pathway.     

Leucine‐rich glioma inactivated 3 promotes HaCaT keratinocyte migration

Our finding that human skin expresses leucine‐rich glioma inactivated 3 (LGI3) raises the question of the function of this cytokine in keratinocytes. We have shown that LGI3 stimulates human HaCaT keratinocyte migration without affecting viability or proliferation. Western blot analysis showed that LGI3 induced focal adhesion kinase activation, Akt phosphorylation, and glycogen synthase kinase 3β (GSK3β) phosphorylation in these cells. Using the scratch wound assay and a modified Boyden chamber, we found that LY294002, a selective phosphatidylinositol 3‐kinase inhibitor, and LiCl, a selective GSK3β inhibitor, abolished LGI3‐induced cell migration. We tested β‐catenin levels after LGI3 treatment because the Akt‐GSK3β pathway regulates β‐catenin accumulation, and β‐catenin promotes cell migration. LGI3 treatment increased β‐catenin protein and nuclear localization, whereas LY294002 prevented LGI3‐induced focal adhesion kinase and Akt activation as well as β‐catenin accumulation. Overall, these data suggest that LGI3 stimulates HaCaT cell migration following β‐catenin accumulation through the Akt pathway.     

Effects of hyperparathyroidism patients’ serum and klotho protein on the apoptosis of human umbilical vein endothelial cells

Objective To investigate the effects and underlying mechanism of secondary hyperparathyroidism (SHPT) patients’serum and klotho protein on the apoptosis of human umbilical vein endothelial cells (HUVECs). Methods Three types of mixed serum from 15 patients with SHPT (serum S), 10 CKD stage 5 patients without SHPT (serum C) and 15 healthy volunteers (serum H) were collected. HUVECs were incubated with 10% serum H,10% serum C, 10% serum S and 10% serum S plus klotho respectively. The apoptosis rate of endothelial cells was evaluated by flow cytometry. The activity of Caspase-3 was measured by spectrophotometry. The levels of AKT and phosphorylated forms of AKT (p- AKT) were detected by Western blotting (with or without PI3K/AKT inhibitor LY294002). Results The apoptosis of HUVECs was both induced by the serum S and serum C. The apoptosis rate was greater in serum S group than that in serum C group (P＜0.05). The apoptosis was partly inhibited when klotho protein (50-100 μg/L) was added (P＜0.05), accompanying the up-regulation of p-AKT. The above effects could be blocked by LY294002. The activity of Caspase-3 was up-regulated in SHPT group compared to healthy control group (P＜0.05) and the up-regulation could also be inhibited by klotho protein (P＜0.05). Conclusions The apoptosis of HUVECs is induced by the serum from CKD stage 5 patients without SHPT and SHPT patients. Klotho protein can protect the HUVECs from apoptosis by up-regulating p-AKT and inhibiting Caspase-3.     

LY294002, a PI3K pathway inhibitor,prevents leptin‐induced adverse effects on spermatozoa in Sprague‐Dawley rats

This study examined the effects of PI3K and AMPK signalling pathway inhibitors on leptin‐induced adverse effects on rat spermatozoa. Sprague‐Dawley rats, aged 14–16 weeks, were randomised into control, leptin‐, leptin + dorsomorphin (AMPK inhibitor)‐, and leptin+LY294002 (PI3K inhibitor)‐treated groups with six rats per group. Leptin was given once daily for 14 days via the intraperitoneal (i.p.) route at a dose of 60 ug kg^?1 body weight. Rats in the leptin and inhibitor‐treated groups received concurrently either dorsomorphin (5 mg kg^?1 day^?1) or LY294002 (1.2 mg kg^?1 day^?1) i.p. for 14 days. Controls received 0.1 ml of normal saline. Upon completion, sperm count, sperm morphology, seminiferous tubular epithelial height (STEH), seminiferous tubular diameter (STD), 8‐hydroxy‐2‐deoxyguanosine (8‐OHdG) and phospho‐Akt/total Akt ratio were estimated. Data were analysed using ANOVA. Sperm count, STEH and STD were significantly lower, while the percentage of spermatozoa with abnormal morphology and the level of 8‐OHdG were significantly higher in rats treated with leptin and leptin + dorsomorphin when compared to those in controls and LY294002‐treated rats. Testicular phospho‐Akt/total Akt ratio was significantly higher in leptin and leptin + LY294002‐treated rats. In conclusion, LY294002 prevents leptin‐induced changes in rat sperm parameters, suggesting the potential role of the PI3K signalling pathway in the adverse effects of leptin on sperm parameters.     

Pancreatic cancer cell proliferation is phosphatidylinositol 3-kinase dependent

BACKGROUND: Genetic mutations found in pancreatic cancer (K-ras, p16, p53) lead to inappropriate cellular proliferation. Mitogens stimulate proliferation via the phosphatidylinositol 3-kinase (PI3K)- and/or the p44/42-mitogen-activated protein kinase [p44/42-MAPK or extracellular signal-regulated kinase (ERK)] signaling pathways. We examined whether inhibition of either PI3K or ERK could limit proliferation in human pancreatic cancer. METHODS: Proliferation was stimulated in quiescent human pancreatic cancer cell lines (BxPC3 and Panc-1) by 10% fetal calf serum (FCS). In certain samples, PD98059 (an ERK inhibitor) or LY294002 (a PI3K inhibitor) was also added. AKT phosphorylation (indicating PI3K activity) and ERK phosphorylation (ERK activation) were determined by Western blot. Cell viability was determined by MTT assay. Cell cycle progression and apoptosis were determined by flow cytometry. A two-tailed t test was used for statistical analysis of the data (significance P < 0.05). RESULTS: LY294002 inhibited the PI3K pathway without affecting ERK activation in response to serum. PD98059 inhibited the ERK pathway specifically. In both BxPC-3 and Panc-1 cell lines, LY294002 inhibited serum-induced proliferation. This was associated with G(1) cell cycle arrest and with an increase in the rate of apoptosis. PD98059 inhibited proliferation only in BxPC3 cells, and to a lesser degree than did LY294002. CONCLUSIONS: PI3K signaling appears to be necessary for G(1)-to-S phase progression and proliferation in pancreatic cancer cells. ERK plays a lesser role in mitogen-induced proliferation. Pharmacological inhibition of PI3K may decrease proliferation, increase apoptosis, and potentially confer therapeutic benefit in pancreatic cancer.     

Interaction of epidermal growth factor, Ca2+, and matrix metalloproteinase-9 in primary keratinocyte migration

Elevations of epidermal growth factor (EGF) and Ca²⁺ concentrations in the wound site are associated with reepithelialization during wound healing. In addition, Ca²⁺ and EGF can both induce increases in matrix metalloproteinase‐9 (MMP‐9) synthesis. However, little is known about the interplay of these events in regulating the migration properties of primary keratinocytes on collagen I, the most abundant extracellular matrix component in the skin. We found that EGF stimulated both chemokinetic and chemotactic migration of primary keratinocytes on collagen I; however, MMP‐9 was required for EGF‐stimulated chemotaxis but not EGF‐stimulated chemokinesis. Calcium at 0.5 mM stimulated chemokinetic migration of keratinocytes. Together, Ca²⁺ and EGF stimulated higher levels of chemokinesis than either stimulus alone. Furthermore, Ca²⁺ could restore the ability of keratinocytes from MMP‐9 null mice to undergo EGF‐stimulated chemotaxis. The phosphatidylinositol‐3 kinase inhibitor LY294002 inhibited both EGF‐ and Ca²⁺‐stimulated chemokinetic migration. In contrast, the MEK inhibitor PD98059 blocked Ca²⁺‐ but not EGF‐stimulated chemokinetic migration of keratinocytes. A combination of PD98059 and LY294002 was required to inhibit Ca²⁺ enhancement of EGF‐stimulated migration completely. Calcium‐stimulated chemokinesis was completely blocked by either the protein kinase C‐α inhibitor Gö6976 or the src/fyn inhibitor PP2. Using primary keratinocytes, our results showed how the combined action of Ca²⁺, EGF, and MMP‐9 regulated the contributions of extracellular‐regulated kinase and phosphatidylinositol‐3 kinase toward chemokinetic and chemotactic migration of keratinocytes.     

Effects of melatonin on spinal cord injury‐induced oxidative damage in mice testis

This study evaluated the effects of melatonin on spinal cord injury (SCI)‐induced oxidative damage in testes. Adult male C57BL/6 mice were randomly divided into sham‐, SCI‐ or melatonin (10 mg/kg, i.p.)‐treated SCI groups. To induce SCI, a standard weight‐drop method that induced a contusion injury at T10 was used. After 1 week, testicular blood flow velocity was measured using the Laser Doppler Line Scanner. Malondialdehyde (MDA), glutathione (GSH), oxidised glutathione (GSSG) and myeloperoxidase (MPO) were measured in testis homogenates. Microvascular permeability of the testes to Evan's Blue was examined by spectrophotometric and fluorescence microscopic quantitation. The tight junction protein zonula occludens‐1 (ZO‐1) and occludin in testes were assessed by immunoblot analysis. Melatonin increased the reduced blood flow and decreased SCI‐induced permeability of capillaries. MDA levels and MPO activity were elevated in the SCI group compared with shams, which was reversed by melatonin. In contrast, SCI‐induced reductions in GSH/GSSG ratio were restored by melatonin. Decreased expression of ZO‐1 and occludin was observed, which was attenuated by melatonin. Overall, melatonin treatment protects the testes against oxidative stress damage caused by SCI.     

Inhibition of the PI3K/AKT Pathway Reduces Tumor Necrosis Factor‐Alpha Production in the Cellular Response to Wear Particles In Vitro

Joint replacement is the most effective treatment for end‐stage osteoarticular disease. However, macrophage‐mediated aseptic loosening of joint prosthesis severely hampers the clinical effects of joint replacement. Until now, the mechanism by which macrophages regulate the secretion of inflammatory cytokines after particle stimulation is not clear. It is well known that the PI3K/AKT pathway participates in multiple cellular processes, including cell growth, survival, and inflammation. However, whether the PI3K/AKT pathway participates in the proinflammatory response of macrophages after particle stimulation and secondary aseptic loosening is still unknown. In this study, ceramic and titanium particles of different sizes were prepared to stimulate macrophages. LY294002, a specific inhibitor of PI3K, was pretreated prior to particle stimulation. The expression of tumor necrosis factor‐alpha (TNF‐α) and all the subunits of PI3K and AKT were detected by real‐time polymerase chain reaction, enzyme‐linked immunosorbent assay, and Western blot. The result showed that LY294002 could suppress the RNA and protein expression of TNF‐α in RAW264.7 cells after stimulation of different particles. The subunits of PI3K (p110β and p85β), followed by activation of phosphor‐AKT (Ser473), participated in the regulation of activating macrophages by wear particles, ultimately resulting in the secretion of TNF‐α.     

The influence of Phosphatidylinositol 3-kinase/Akt Pathway on the Ischemic Injury during Rat Liver Graft Preservation

We aimed to investigate the role of phosphatidylinositol 3 (PI3)-kinase/Akt pathway on ischemic injury. Rat liver grafts were preserved in UW solution with different treatments and were compared by 1-week survival rates and morphological changes with those of the control group. PI3-kinase/Akt was significantly activated at the sites of Thr 308 and Ser 473 in the preserved grafts. Downstream target proteins, glycogen synthase kinase-3beta (GSK-3beta) and caspase-9, were inactivated. However, survival signal transduction from Akt to Bad was blocked by calcium release after activation of PI3-kinase/Akt. Significant activation of caspase-12, -3 and -7 contributed to cell apoptosis and severe ischemic injury was shown after 7 h of preservation by UW solution with insulin. Downregulation of phospho-Akt at Thr 308 and Ser 473 was due to partial inhibition of PI3-kinase/Akt pathway by LY294002. Activation of GSK-3beta and inactivation of caspase-12 and Bad could be found in the LY294002 groups in which the liver grafts showed less ischemic injury. Higher 1-week survival rates in the heparin, LY294002, and glucagon groups confirmed the dysregulation of the pathway. In conclusion, PI3-kinase/Akt pathway was dysregulated and contributed to ischemic injury during preservation. Heparin and LY294002 could improve graft viability by maintaining calcium homeostasis during preservation.     

PI3K/AKT信号通路及AKR1C3在人瘢痕疙瘩形成中的作用机制研究

目的探讨磷脂酰肌醇-3-激酶(PI3K)/蛋白激酶B(AKT)信号通路、活性氧簇(ROS)、醛酮还原酶家族1成员C3(AKR1C3)在瘢痕疙瘩形成中的可能作用及机制。方法从昆明医科大学第一附属医院皮肤科收集9例瘢痕疙瘩组织标本(男6例,女3例,年龄24~40岁),以及6例进行其他手术的志愿者正常皮肤组织标本(男4例,女2例,年龄20~45岁),部分行组织包埋,部分行成纤维细胞原代培养。(1)免疫组织化学检测瘢痕疙瘩和正常皮肤组织中AKT(丝氨酸磷酸化位点473)[p-AKT(S473)]、AKT(苏氨酸磷酸化位点308)[p-AKT(T308)]和AKR1C3的蛋白相对表达量。(2)CCK-8法检测不同浓度(0、5、10、15、20、25、30、35、40、45、50 mmol/L)PI3K特异性抑制剂2-吗啉代-8-苯基色酮(LY294002)对瘢痕疙瘩成纤维细胞增殖的抑制作用,并筛选出LY294002最佳的实验浓度。(3)以ROS检测试剂盒分别检测不同浓度(0、4、6、8、10、12 mmol/L)ROS抑制剂N-乙酰半胱氨酸(NAC)和15 mmol/L LY294002对瘢痕疙瘩成纤维细胞内ROS水平的影响。(4)将瘢痕疙瘩或正常皮肤成纤维细胞分为对照组(正常培养不进行任何处理)、二甲基亚砜(DMSO)组(0.002%DMSO处理)、LY294002组(15 mmol/L LY294002处理)和NAC组(6 mmol/L NAC处理),定量PCR(qPCR)和蛋白质印迹法分别检测成纤维细胞中AKT mRNA、AKR1C3 mRNA及p-AKT(S473)、p-AKT(T308)和AKR1C3蛋白的表达水平。采用SPSS 20.0软件进行统计学分析,数据以±s表示,两组间比较采用独立样本t检验,多组间比较采用单因素方差分析,两两多重比较采用SNK-q检验,P<0.05表示差异有统计学意义。结果(1)免疫组织化学检测结果显示,瘢痕疙瘩组织中p-AKT(S473)、p-AKT(T308)和AKR1C3的蛋白表达水平分别为16.75±3.30、16.20±1.56、26.69±2.50,均显著高于正常皮肤组织的4.02±1.50、1.82±0.50、1.47±1.07(P<0.01)。(2)瘢痕疙瘩成纤维细胞经不同浓度LY294002干预24 h后,15~50 mmol/L LY294002组成纤维细胞增殖抑制率显著高于对照组(0 mmol/L组)(P<0.01)。LY294002最佳实验浓度为15 mmol/L。(3)不同浓度NAC作用于瘢痕疙瘩成纤维细胞1 h后,各组间ROS水平差异有统计学意义(P<0.01),且6 mmol/L NAC组ROS水平(0.72±0.03)最低。15 mmol/L LY294002组ROS水平显著低于对照组(0 mmol/L组)(0.80±0.01 vs.0.86±0.01,P<0.01)。(4)qPCR检测结果表明,瘢痕疙瘩成纤维细胞对照组中AKT、AKR1C3 mRNA表达量分别为1.38±0.09、1.40±0.05,明显高于正常皮肤成纤维细胞的0.97±0.10、0.98±0.03(P<0.01);经15 mmol/L LY294002处理后,瘢痕疙瘩成纤维细胞AKT mRNA表达量明显低于正常皮肤(0.73±0.05 vs.0.89±0.06,P<0.01);经6 mmol/L NAC处理后,瘢痕疙瘩成纤维细胞AKR1C3 mRNA低于正常皮肤(0.43±0.05 vs.0.86±0.03,P<0.01)。蛋白质印迹法检测结果显示,瘢痕疙瘩成纤维细胞中p-AKT(S473)、p-AKT(T308)、AKR1C3蛋白表达量分别为1.19±0.21、0.92±0.04、0.73±0.08,明显高于正常皮肤的0.24±0.06、0.33±0.05、0.31±0.05(P<0.01);经15 mmol/L LY294002和6 mmol/L NAC处理后,瘢痕疙瘩成纤维细胞中p-AKT(S473)蛋白表达量分别为0.92±0.04、0.80±0.20,p-AKT(T308)蛋白表达量分别为0.42±0.04、0.81±0.05,均明显高于正常皮肤(0.23±0.03、0.22±0.05,0.30±0.06、0.32±0.05),但瘢痕疙瘩成纤维细胞AKR1C3蛋白表达量(0.23±0.05)在15 mmol/L LY294002处理后低于正常皮肤(0.30±0.07),在6 mmol/L NAC处理后(0.33±0.07)高于正常皮肤(0.28±0.06)(P>0.05)。结论活化的PI3K/AKT信号通路和AKR1C3促进了瘢痕疙瘩成纤维细胞增殖及瘢痕疙瘩形成。同时,瘢痕疙瘩成纤维细胞内AKR1C3的升高可加速ROS升高。     

胰岛素对烧伤血清诱导血管内皮细胞核因子κB核移位的抑制作用

目的 了解胰岛素对烧伤血清诱导的血管内皮细胞NF-κB核移位的抑制作用及其相关机制.方法 体外培养人脐静脉内皮细胞(HUVEC).按照随机数字表法将细胞分为5组:空白对照组,不加任何刺激因素常规培养;正常血清对照组和烧伤血清刺激组,分别用含体积分数20%健康人血清、体积分数20%烧伤患者血清的培养液培养;烧伤血清+胰岛素处理组,在烧伤血清刺激组培养液成分的基础上添加胰岛素(终浓度1×10-7mol/L)进行培养;抑制剂预处理组,预先加入蛋白激酶B(PKB或Akt)特异性抑制剂LY294002(50μmol/L)孵育细胞,30 min后改用培养液(成分同烧伤血清+胰岛素处理组)培养.6 h后,采用扫描电镜观察各组HUVEC损伤情况;用流式细胞仪检测细胞凋亡率;蛋白质印迹法检测细胞胞质磷酸化κB-α抑制蛋白(p-IκB-α)和磷酸化Akt(p-Akt)水平,以及胞核NF-κB-p65的蛋白表达变化.结果 (1)扫描电镜观察:与空白对照组HUVEC比较,烧伤血清刺激组、抑制剂预处理组细胞收缩明显,细胞间呈锯齿状连接或连接消失,胞核结构不规整.正常血清对照组及烧伤血清+胰岛素处理组细胞结构有轻微改变,但细胞延展性及胞核结构明显好于烧伤血清刺激组.(2)细胞凋亡率:空白对照组为(15.7±2.2)%.烧伤血清刺激组为(28.5±2.3)%,烧伤血清+胰岛素处理组为(22.3±1.8)%,抑制剂预处理组为(29.7±2.4)%,均明显高于空白对照组(F=14.288,P<0.05或P<0.01);正常血清对照组细胞凋亡率为(17.0±2.5)%,与空白对照组比较差异无统计学意义(F=14.288,P>0.05).与烧伤血清刺激组相比,烧伤血清+胰岛素处理组细胞凋亡率明显降低(F=14.288,P<0.05).(3)蛋白表达水平:与空白对照组相比,烧伤血清刺激组和抑制剂预处理组细胞胞质p-IκB-α与胞核NF-κB-p65的蛋白表达水平明显升高,p-Akt表达水平明显下降;正常血清对照组和烧伤血清+胰岛素处理组3种蛋白水平均与空白对照组接近.结论 胰岛素通过调节磷脂酰肌醇3激酶/Akt信号通路抑制IκB-α磷酸化,继而限制NF-κB核移位,最终发挥改善内皮细胞功能的作用.     

Rosiglitazone (BRL 49653) enhances insulin secretory response via phosphatidylinositol 3-kinase pathway.

To elucidate the direct effect of rosiglitazone (RSG), a new thiazolidinedione antihyperglycemic agent, on pancreatic insulin secretion, an in situ investigation by rat pancreatic perfusion was performed. At a basal glucose concentration of 6 mmol/l, RSG (0.045-4.5 micromol/l) stimulated insulin release in a dose-dependent manner. In addition, 4.5 micromol/l RSG potentiated the glucose (10 mmol/l)-induced insulin secretion. Both the first and second phases of glucose-induced insulin secretion were significantly enhanced by RSG, by 80.7 and 52.4%, respectively. The effects of RSG on insulin secretion were inhibited by a phosphatidylinositol 3-kinase (PI3K) inhibitor, LY294002. In contrast, the glucose-stimulated insulin secretion was not affected by LY294002. The potentiation effect of RSG on glucose-stimulated insulin secretion, in both the first and second phases, was significantly blocked by LY294002. These results suggest that RSG has a direct potentiation effect on insulin secretion in the presence of 10 mmol/l glucose, mediated through PI3K activity. The inability of LY294002 to inhibit glucose-induced insulin secretion suggests that different pathways are responsible for glucose and RSG signaling.     

Isoflurane Postconditioning Prevents Opening of the Mitochondrial Permeability Transition Pore through Inhibition of Glycogen Synthase Kinase 3β

Background: Postischemic administration of volatile anesthetics activates reperfusion injury salvage kinases and decreases myocardial damage. However, the mechanisms underlying anesthetic postconditioning are unclear.

Methods: Isolated perfused rat hearts were exposed to 40 min of ischemia followed by 1 h of reperfusion. Anesthetic postconditioning was induced by 15 min of 2.1 vol% isoflurane (1.5 minimum alveolar concentration) administered at the onset of reperfusion. In some experiments, atractyloside (10 [mu]m), a mitochondrial permeability transition pore (mPTP) opener, and LY294002 (15 [mu]m), a phosphatidylinositol 3-kinase inhibitor, were coadministered with isoflurane. Western blot analysis was used to determine phosphorylation of protein kinase B/Akt and its downstream target glycogen synthase kinase 3[beta] after 15 min of reperfusion. Myocardial tissue content of nicotinamide adenine dinucleotide served as a marker for mPTP opening. Accumulation of MitoTracker Red 580 (Molecular Probes, Invitrogen, Basel, Switzerland) was used to visualize mitochondrial function.

Results: Anesthetic postconditioning significantly improved functional recovery and decreased infarct size (36 +/- 1% in unprotected hearts vs. 3 +/- 2% in anesthetic postconditioning; P < 0.05). Isoflurane-mediated protection was abolished by atractyloside and LY294002. LY294002 inhibited isoflurane-induced phosphorylation of protein kinase B/Akt and glycogen synthase kinase 3[beta] and opened mPTP as determined by nicotinamide adenine dinucleotide measurements. Atractyloside, a direct opener of the mPTP, did not inhibit phosphorylation of protein kinase B/Akt and glycogen synthase kinase 3[beta] by isoflurane but reversed isoflurane-mediated cytoprotection. Microscopy showed accumulation of the mitochondrial tracker in isoflurane-protected functional mitochondria but no staining in mitochondria of unprotected hearts.     

重组人红细胞生成素预处理对肾小管上皮细胞缺血再灌注损伤中PI3K-Akt-GSK-3β通路的调控作用

目的 探讨磷脂酰肌醇-3激酶（PI3K）-蛋白激酶B（Akt）-糖原合成酶激酶3β（GSK-3β）通路对人肾小管上皮细胞（HK-2）缺血再灌注（IR）损伤过程中细胞凋亡的调控及重组人红细胞生成素（rHuEPO）的保护作用。 方法 正常培养的HK-2细胞,分为7组：正常对照组、IR组、LY294002干预组（PI3K-Akt阻断剂,10 μmol/L）、LiCl干预组（GSK-3β阻断剂,20 μmol/L）、rHuEPO干预组（20 U/L）、rHuEPO+LY294002干预组、rHuEPO+LiCl干预组。Western印迹法检测Akt（Ser473）、GSK-3β（Ser9）及半胱氨酸天冬氨酸蛋白酶（caspase-3）活性; MTT法检测细胞活力;Annexin V和PI染色结合流式细胞仪技术检测细胞凋亡。 结果 IR损伤诱导HK-2细胞凋亡率上调（15.20%±1.43％）、Akt活性水平下降、GSK-3β及caspase-3酶活性水平上调,与正常对照组相比,差异有统计学意义（P < 0.05）。与IR组相比,LY294002干预使细胞凋亡率进一步上调（18.20%±2.06％）、Akt活性水平下调、GSK-3β及caspase-3酶活性上调,LiCl干预使细胞凋亡率下调（12.30%±0.85％）、Akt活性水平上调、GSK-3β及caspase-3酶活性下调,差异均有统计学意义（P < 0.05）。rHuEPO干预与IR组相比,细胞凋亡率下降（11.10%±1.62％）、Akt活性水平升高而GSK-3β及caspase-3酶活性下调,差异有统计学意义（P < 0.05）。与rHuEPO干预相比,rHuEPO+LY294002双干预细胞凋亡率升高（13.40%±1.94％）、Akt活性水平下降而GSK-3β及caspase-3酶活性上调,rHuEPO+LiCl双干预细胞凋亡率下调（7.50%±1.31％）、Akt活性水平上升而GSK-3β及caspase-3酶活性下降,差异均有统计学意义（P < 0.05）。 结论 IR损伤可引起肾小管上皮细胞凋亡,Akt活性降低及GSK-3β活性升高,影响caspase-3依赖的外源性凋亡途径可能是其凋亡机制之一。rHuEPO可通过增强Akt活性,降低GSK-3β及caspase-3酶活性,从而减轻细胞凋亡,对HK-2 IR损伤有一定的保护作用。     

Dickkopf‐related protein 3 promotes pathogenic stromal remodeling in benign prostatic hyperplasia and prostate cancer

BACKGROUND

Compartment‐specific epithelial and stromal expression of the secreted glycoprotein Dickkopf‐related protein (Dkk)‐3 is altered in age‐related proliferative disorders of the human prostate. This study aimed to determine the effect of Dkk‐3 on prostate stromal remodeling that is stromal proliferation, fibroblast‐to‐myofibroblast differentiation and expression of angiogenic factors in vitro.

METHODS

Lentiviral‐delivered overexpression and shRNA‐mediated knockdown of DKK3 were applied to primary human prostatic stromal cells (PrSCs). Cellular proliferation was analyzed by BrdU incorporation ELISA. Expression of Dkk‐3, apoptosis‐related genes, cyclin‐dependent kinase inhibitors and angiogenic factors were analyzed by qPCR, Western blot analysis or ELISA. Fibroblast‐to‐myofibroblast differentiation was monitored by smooth muscle cell actin and insulin‐like growth factor binding protein 3 mRNA and protein levels. The relevance of Wnt/β‐catenin and PI3K/AKT signaling pathways was assessed by cytoplasmic/nuclear β‐catenin levels and phosphorylation of AKT.

RESULTS

Knockdown of DKK3 significantly attenuated PrSC proliferation as well as fibroblast‐to‐myofibroblast differentiation and increased the expression of the vessel stabilizing factor angiopoietin‐1. DKK3 knockdown did not affect subcellular localization or levels of β‐catenin but attenuated AKT phosphorylation in PrSCs. Consistently the PI3K/AKT inhibitor LY294002 mimicked the effects of DKK3 knockdown.

CONCLUSIONS

Dkk‐3 promotes fibroblast proliferation and myofibroblast differentiation and regulates expression of angiopoietin‐1 in prostatic stroma potentially via enhancing PI3K/AKT signaling. Thus, elevated Dkk‐3 in the stroma of the diseased prostate presumably regulates stromal remodeling by enhancing proliferation and differentiation of stromal cells and contributing to the angiogenic switch observed in BPH and PCa. Therefore, Dkk‐3 represents a potential therapeutic target for stromal remodeling in BPH and PCa. Prostate 73: 1441–1452, 2013. © 2013 Wiley‐Liss, Inc. The Prostate published by Wiley Periodicals, Inc.     

补肾固本方对大鼠骨质疏松模型中PI3K/AKT/mTOR信号通路表达的调控研究

目的观察补肾固本方对去卵巢骨质疏松(osteoporosis,OP)大鼠骨组织中PI3K/AKT/mTOR信号通路的影响,探讨补肾固本方干预OP的作用机制。方法将100只SD大鼠随机分为5组:正常组(C组)、模型组(M组)、补肾固本方组(B组)、补肾固本方+PI3k受体特异性阻断剂LY294002组(B+L组)、PI3k受体特异性阻断剂LY294002组(L组),除正常组外,其余4组建立去卵巢大鼠OP模型。药物连续干预12周后,采用ELISA方法检测血清中E2、BGP、ALP水平,实时荧光定量聚合酶链式反应(Real-time PCR)检测各组股骨组织中LC3、Beclin1、caspase-9 mRNA的表达情况,蛋白质印迹法(Western blot)检测各组股骨组织中PI3K、AKT、mTOR蛋白的表达。结果补肾固本方可显著增高OP大鼠血清E2水平,降低BGP、ALP水平,显著上调LC3、Beclin1表达水平,降低caspase-9、PI3K、p-AKT、mTOR的表达;而上述变化能够被PI3k受体特异性阻断剂LY294002所阻断,且其差异具有统计学意义(P0.05)。结论补肾固本方减少去卵巢后大鼠OP的发生,其机制可能与抑制PI3K/AKT/mTOR信号通路及其下游基因蛋白表达有关。     

烧伤后肠上皮通透性变化机制和对策

After a series of studies, we found that the intestinal permeability was increased, tight junction protein (zonula occluden-1 ) obviously decreased and redistributed, accompanied by an increase in expression of myosin light chain (MLC) phosphorylation in severely burned rats. After using inhibitor of MLC kinase ( ML-9 2mg/kg) or of Rho-associated kinase (Y-27632 2mg/kg), above-mentioned changes could be alleviated. Therefore, to regulate the MLC phosphorylation of tight junction protein and perijunctional actin-myosin ring may be one of the key links to lessen the intestinal epithelium permeability after burn injury.     

Insulin‐like growth factor 2 (IGF‐2) potentiates BMP‐9‐induced osteogenic differentiation and bone formation

Efficient osteogenic differentiation and bone formation from mesenchymal stem cells (MSCs) should have clinical applications in treating nonunion fracture healing. MSCs are adherent bone marrow stromal cells that can self‐renew and differentiate into osteogenic, chondrogenic, adipogenic, and myogenic lineages. We have identified bone morphogenetic protein 9 (BMP‐9) as one of the most osteogenic BMPs. Here we investigate the effect of insulin‐like growth factor 2 (IGF‐2) on BMP‐9‐induced bone formation. We have found that endogenous IGF‐2 expression is low in MSCs. Expression of IGF‐2 can potentiate BMP‐9‐induced early osteogenic marker alkaline phosphatase (ALP) activity and the expression of later markers. IGF‐2 has been shown to augment BMP‐9‐induced ectopic bone formation in the stem cell implantation assay. In perinatal limb explant culture assay, IGF‐2 enhances BMP‐9‐induced endochondral ossification, whereas IGF‐2 itself can promote the expansion of the hypertropic chondrocyte zone of the cultured limb explants. Expression of the IGF antagonists IGFBP3 and IGFBP4 leads to inhibition of the IGF‐2 effect on BMP‐9‐induced ALP activity and matrix mineralization. Mechanistically, IGF‐2 is further shown to enhance the BMP‐9‐induced BMPR‐Smad reporter activity and Smad1/5/8 nuclear translocation. PI3‐kinase (PI3K) inhibitor LY294002 abolishes the IGF‐2 potentiation effect on BMP‐9‐mediated osteogenic signaling and can directly inhibit BMP‐9 activity. These results demonstrate that BMP‐9 crosstalks with IGF‐2 through PI3K/AKT signaling pathway during osteogenic differentiation of MSCs. Taken together, our findings suggest that a combination of BMP‐9 and IGF‐2 may be explored as an effective bone‐regeneration agent to treat large segmental bony defects, nonunion fracture, and/or osteoporotic fracture. © 2010 American Society for Bone and Mineral Research.     

p38丝裂原活化蛋白激酶在烧伤大鼠急性肺损伤中的作用机制

目的　研究 p38丝裂原活化蛋白激酶 (MAPK)信号转导通路在严重烧伤大鼠肺部促炎细胞因子肿瘤坏死因子α(TNF α)、白细胞介素 1β(IL 1β)产生及肺血管内皮细胞损伤中的作用和相关机制。　方法　健康成年雄性SD大鼠 4 8只 ,随机分为假烫 (A)组、烫伤对照 (B)组和烫伤 p38MAPK抑制剂SB2 0 35 80(C)组 ,每组各 16只。观察烫伤 (以下称烧伤 ) 2 4h后大鼠血清和支气管肺泡灌洗液 (BALF)中TNF α和IL 1β含量、血浆和肺脏微血管vonWillebrand因子 (vWF)含量、肺脏激活蛋白 1(AP 1)活性等指标的改变。　 结果　B组大鼠烧伤后 2 4h血清和BALF中TNF α和IL 1β含量明显增高 ,血浆vWF含量为 (194 .2± 2 8.3) % ,显著高于A组的 (93.2± 14 .3) % (P <0.0 1);肺脏微血管vWF含量的积分值为 1.1± 0 .3,显著低于A组的 3.3± 0 .4 (P <0.0 1);其肺脏AP 1活性上升。C组血清和BALF中TNF α和IL 1β含量、血浆及肺脏微血管vWF含量、肺脏AP 1的活性较B组变化幅度明显偏小。　结论　p38MAPK活化后 ,通过活化转录因子AP 1,介导了严重烧伤后肺脏促炎性细胞因子TNF α和IL 1β的产生和肺血管内皮细胞的损伤