丙戊酸联合HA14-1诱导Bcl-2高表达的白血病细胞株BALL-1凋亡

目的观察体内外丙戊酸(VPA)和HA14-1联合应用对Bcl-2高表达的白血病细胞的杀伤效能及对外周血象的影响。方法(1)将BALL-1分为空白对照组1、mmol/L VPA组5、mmol/L VPA组、15 mmol/L VPA组,作用72 h,流式细胞仪检测各组细胞凋亡结果;(2)将BALL-1分为对照组、VPA组、HA14-1组、VPA+HA14-1组,作用后流式细胞法检测各组凋亡率;(3)每组6只NOD/SCID鼠在每只鼠接种1×107/0.2 ml BALL-1后24 h按如下分组进行实验:①对照组;②HA14-1组,经尾静脉注射灭菌HA14-1 25 mg.kg-1.d-1,共7天;③VPA组,注射灭菌VPA 250 mg.kg-1.d-1,共7天;④HA14-1+VPA组,注射灭菌HA14-1 25 mg.kg-1.d-1,4小时后再注射灭菌VPA 250 mg.kg-1.d-1,共7天。记录各组小鼠的存活时间。(4)将普通小白鼠共24只按(3)方法进行分组,比较几组普通小鼠的生存率、存活时间,及外周血细胞计数。结果(1)VPA15 mmol/L作用72 h BALL-1凋亡率为(24.8±2.8)%,与其它3组比较P<0.01;另3组之间比较P>0.05。(2)HA14-1组、VPA组凋亡率分别为(4.6±0.1)%(、4.8±0.5)%,与对照组比较,P>0.05。HA14-1+VPA组凋亡率高达(76.5±6.9)%,与另3组比较P<0.01。(3)HA14-1+VPA组小鼠生存天数为(87.5±4.5)天,显著长于其他3组,而其他3组之间无差异。(4)HA14-1单独作用组和HA14-1与VPA联合作用组表现为白细胞与血小板轻微而短期下降,而小鼠的生存率、存活时间无显著性差异。结论HA14-1与VPA联合用药,可克服Bcl-2高表达造成的对VPA的抗性。     

Mitochondrial targeting by use of lipid nanocapsules loaded with SV30, an analogue of the small-molecule Bcl-2 inhibitor HA14-1

Taking advantage from the development of SV30, a new analogue of the pro-apoptotic molecule HA14-1, the aim of this study was to functionally evaluate SV30 and to develop safe nanocarriers for its administration. By using an inversion phase process, 57 nm organic solvent-free lipid nanocapsules loaded with SV30 (SV30-LNCs) were formulated. Biological performance of SV30 and SV30-LNCs were evaluated on F98 cells that express Bax and Bcl-2, through survival assays, HPLC, flow cytometry, confocal microscopy and spectral imaging. We observed that SV30 alone or in combination with paclitaxel, etoposide or beam radiation could trigger cell death in a similar fashion to HA14-1. Although partially blocked by Z-VAD-fmk, this effect was coincident to caspase-3 activation. Hence, we established that SV30-LNCs improved SV30 biological activity together with a potentiation of the mitochondrial membrane potential decrease. Interestingly, flow cytometry and confocal analysis indicated that SV30 itself conferred to LNCs improved mitochondrial targeting skills that may present a great interest toward the development of mitochondria targeted nanomedicines.     

Sulindac sulfide-induced apoptosis is enhanced by a small-molecule Bcl-2 inhibitor and by TRAIL in human colon cancer cells overexpressing Bcl-2

Sulindac is a nonsteroidal anti-inflammatory drug (NSAID) that induces apoptosis in cultured colon cancer cells and in intestinal epithelia in association with its chemopreventive efficacy. Resistance to sulindac is well documented in patients with familial adenomatous polyposis; however, the molecular mechanisms underlying such resistance remain unknown. We determined the effect of ectopic Bcl-2 expression upon sulindac-induced apoptotic signaling in SW480 human colon cancer cells. Sulindac sulfide activated both the caspase-8-dependent and mitochondrial apoptotic pathways. Ectopic Bcl-2 attenuated cytochrome c release and apoptosis induction compared with SW480/neo cells. Coadministration of sulindac sulfide and the small-molecule Bcl-2 inhibitor HA14-1 increased apoptosis induction and enhanced caspase-8 and caspase-9 cleavage, Bax redistribution, and cytochrome c and second mitochondria-derived activator of caspase release. Given that sulindac sulfide activated caspase-8 and increased membrane death receptor (DR4 and DR5) protein levels, we evaluated its combination with the endogenous death receptor ligand tumor necrosis factor-related apoptosis-inducing ligand (TRAIL). Coadministration of sulindac sulfide and TRAIL cooperatively enhanced apoptotic signaling as effectively as did HA14-1. Together, these data indicate that HA14-1 or TRAIL can enhance sulindac sulfide-induced apoptosis and represent novel strategies for circumventing Bcl-2-mediated apoptosis resistance in human colon cancer cells.     

钙拮抗剂对缺血性脑损伤后Bcl-2和Bax基因表达的作用

INTRODUCTIONApoptosisisrecognizedtooccurasaresultofexecutionofexquisitelyregulatedgeneticprogram．Apoptosisisimplicatedinthepathogen－esisofanincreasingnumberofdiseasesandconsideredtobein－volvedinpathologicalcelldeathaswell．Recentevidenceindicatesasignificantcontributionofapoptosistothedelayedneuronaldeathinthehippocampusaftertransientglobalischemia[１]．Bcl－２andBaxhavebeenrecognizedtoplayanimportantroleintheregulationofcelldeathinthenervoussystem[２]．Nimodipineisaneuro－protectived…     

严重颅脑损伤后细胞凋亡状态及相关基因Bcl-2、Bax的表达

目的 探讨严重颅脑损伤后Bel-2、Bax基因表达与细胞凋亡的关系。方法 采用改进的Feeney自由落体损伤模型，应用分子生物学方法——脱氧核糖核苷酸末端转移酶介导的缺口末端标记法(terminal-deoxynucleofidyl transferase mediated nick end labeling，TUNEL)以及免疫组织化学方法，对50只严重颅脑大鼠脑组织中的凋亡细胞和Bel-2、Bax免疫反应阳性的细胞进行观察、统计。结果 损伤组大鼠脑组织中凋亡细胞数明显高于未损伤组，Bel-2、Bax表达也有所增加，同时，损伤组Bax／Bel-2阳性细胞数的比值明显大于未损伤组。结论 Bel-2和Bax表达的比例对严重颅脑损伤后细胞凋亡可能起重要的调控作用。     

The small-molecule Bcl-2 inhibitor HA14-1 interacts synergistically with flavopiridol to induce mitochondrial injury and apoptosis in human myeloma cells through a free radical-dependent and Jun NH2-terminal kinase-dependent mechanism

Interactions between the cyclin-dependent kinase inhibitor flavopiridol and the small-molecule Bcl-2 antagonist HA14-1 were examined in human multiple myeloma cells. Whereas individual treatment of U266 myeloma cells with 10 micromol/L HA14-1 or 100 nmol/L flavopiridol had little effect, exposure of cells to flavopiridol (6 hours) followed by HA14-1 (18 hours) resulted in a striking increase in mitochondrial dysfunction (cytochrome c and Smac/DIABLO release; loss of mitochondrial membrane potential), activation of the caspase cascade, apoptosis, and diminished clonogenic survival. Similar findings were noted in other myeloma cell lines (e.g., MM.1S, RPMI8226, and NCI-H929) as well as in those resistant to dexamethasone and cytotoxic agents (e.g., MM.1R, 8226/Dox40, and 8226/LR5). Combined exposure to flavopiridol and HA14-1 was associated with down-regulation of Mcl-1 and Bcl-xL, Bid cleavage, and mitochondrial translocation of Bax. Flavopiridol/HA14-1-treated cells also exhibited a pronounced activation of Jun NH2-terminal kinase, a modest activation of p38 mitogen-activated protein kinase, and down-regulation of cyclin D1. Flavopiridol/HA14-1-induced apoptosis was associated with a marked increase in reactive oxygen species generation; moreover,both events were attenuated by the antioxidant N-acetyl-l-cysteine. Finally, in contrast to dexamethasone, flavopiridol/HA14-1-induced lethality was unaffected by exogenous interleukin-6 or insulin-like growth factor-I. Together, these findings indicate that flavopiridol and the small-molecule Bcl-2 antagonist HA14-1 cooperate to trigger oxidant injury, mitochondrial dysfunction, caspase activation, and apoptosis in human multiple myeloma cells and suggest that this approach may warrant further evaluation as an antimyeloma strategy.     

缺氧环境中胸腺素β4基因转染骨髓间充质干细胞凋亡率及Bax和Bcl-2的表达

背景：研究表明体外培养细胞加入胸腺素β4能增加细胞的抗凋亡能力,若在缺氧环境中上调胸腺素β4基因在骨髓间充干细胞中的表达,其抗凋亡能力如何改变,目前鲜见报道。
　　目的：观察胸腺素β4基因修饰的骨髓间充质干细胞在缺氧环境中的凋亡率改变,并探讨其是否通过调控Bax、Bcl-2表达影响凋亡能力。
　　方法：将携带有胸腺素β4基因的慢病毒转染骨髓间充质干细胞,转染完毕后利用Western blot法检测胸腺素β4在骨髓间充质干细胞中的表达。将细胞分为胸腺素β4转染组、对照病毒组、未转染组,分别置于缺氧环境中。流式细胞仪检测3组细胞凋亡率;Western blot法检测3组细胞中Bax和Bcl-2蛋白表达情况。
　　结果与结论：Western blot检测结果示,胸腺素β4基因在骨髓间充质干细胞中成功表达。流式细胞仪结果示,胸腺素β4转染组细胞凋亡率较对照病毒组、未转染组低,而对照病毒组、未转染组凋亡率差异无显著性意义。Western blot结果显示,Bcl-2蛋白在胸腺素β4转染组中表达量较对照病毒组、未转染组高,Bax蛋白在胸腺素β4转染组表达量较对照病毒组、未转染组低,而对照病毒组、未转染组中Bax、Bcl-2表达差异无显著性意义。提示过表达胸腺素β4基因可增加骨髓间充质干细胞在缺氧环境中的抗凋亡能力,其可能的作用机制是调控Bax和Bcl-2蛋白表达水平。     

Bcl-2和Bax的表达与乳腺癌转移及预后的关系

目的　探讨Bcl 2和Bax基因在乳腺癌中的表达及与乳腺癌淋巴结转移、预后的关系。方法　应用SP免疫组化染色方法 ,检测 4 0例乳腺癌组织中Bcl 2、Bax的表达情况。结果　无淋巴结转移组Bcl 2阳性表达率与淋巴结转移组有显著差异 (P <0 .0 5 ) ,10年以上存活组Bcl 2阳性表达率与 10年以下存活组有显著差异 (P <0 .0 1)。无淋巴结转移组Bax阳性表达率与淋巴结转移组有显著差异 (P <0 .0 5 ) ,10年以上存活组Bax阳性表达率与 10年以下存活组有显著差异 (P <0 .0 5 )。结论　Bcl 2和Bax表达与乳腺癌淋巴结转移、预后关系密切 ,Bcl 2提示高表达、Bax低表达的乳腺癌患者有低的转移率及好的预后。     

胰岛素对心肺复苏大鼠神经元凋亡及Bcl-2,Bax mRNA表达的影响

目的 探讨脑室内注射胰岛素对心肺复苏(cardiopulmonary resuscitation,CPR)后大鼠海马CA1区神经元凋亡和对抑凋亡因子Bcl-2,促凋亡因子Bax mRNA表达的影响.方法 实验地点在首都医科大学宣武医院试验动物中心.30只雄性SD大鼠随机(随机数字法)分为假手术组(对照组,n=6)、心肺复苏组(复苏组,n=12)及CPR后胰岛素干预组(胰岛素组,n=12).经食道超速起搏诱发6min室颤制备大鼠CPR模型;以CPR后大鼠恢复室上性心率、收缩压超过60 mmHg(1 mmHg=0.133 kPa)并持续10 min以上,作为自主循环恢复(ROCS)标准;ROCS 10 min后,胰岛素组大鼠经立体定位仪定位,脑室内注射12.5 μL(1 U)胰岛素,其余2组大鼠注射等量生理盐水.维持生命体征,CPR后24,72 h,应用实时荧光PCR (Realtime-PCR)测定海马CA1区神经元Bcl-2,Bax mRNA的表达量;CPR后7d,应用TUNEL染色检测海马CA1区神经元凋亡;CPR前后监测大鼠静脉血糖变化.计量资料采用均数±标准差(-x±s),组间比较采用单因素方差分析(ANOVA);相关性统计应用Pearson相关分析,以P＜0.05为差异具有统计学意义.结果 ①CPR后24,72 h,胰岛素组大鼠Bcl-2 mRNA表达量均高于复苏组(1.45±0.05) vs.(0.79±0.01);(0.95±0.06) vs.(0.35±0.03),差异具有统计学意义(P＜0.01).组内比较发现,胰岛素组、复苏组72 h表达均低于24 h(P＜0.01).而胰岛素组与复苏组Bax mRNA表达差异无统计学意义(P＞0.05),胰岛素组、复苏组72 h与24h比较差异无统计学意义(P＞0.05).②CPR后7d,胰岛素组大鼠海马CA1区神经元凋亡计数,复苏组(124.75±17.35)个/mm2明显高于对照组(5.12±3.26)个/mm2和胰岛素组(92.79±7.49)个/mm2,差异具有统计学意义(P＜0.01).③各组大鼠各时间点外周静脉血糖比较无统计学意义(P＞0.05).结论 脑室内注射1U胰岛素,能够促进CPR后大鼠神经元促凋亡因子Bcl-2 mRNA的表达,抑制神经元凋亡,具有神经保护作用.脑室注射1U胰岛素不降低外周血糖.     

全脑缺血再灌注大鼠不同时相海马CA1区Bcl-2、Bcl-xL及Bax蛋白的表达

目的：通过系统观察大鼠全脑缺血－再灌注后不同时相海马CA1区神经元Bcl-2、Bcl-xL及Bax蛋白表达的改变,探讨该区神经元短暂脑缺血后产生选择性敏感的机制。方法：通过四血管闭塞法建立大鼠全脑缺血－再灌注模型,利用免疫组织化学方法观察再灌注后1、3、5日海马CA1区神经元Bcl-2、Bcl-xL及Bax蛋白表达的情况;并同时与海马CA1区神经元的病理形态学改变进行对比。结果：全脑缺血－再灌注后1日,海马CA1区Bcl-2和Bcl-xL蛋白呈阴性表达,Bax蛋白呈弱阳性表达;海马CA1区神经元未见明显形态学改变。全脑缺血－再灌注后3日,海马CA1区Bcl-2和Bcl-xL蛋白表达仍为阴性,而Bax蛋白则呈明显阳性表达;海马CA1区可见部分神经元死亡;全脑缺血－再灌注后5日,海马CA1区Bcl-2、Bcl-xL及Bax蛋白则呈阴性表达;海马CA1区神经元大部分死亡。结论：全脑缺血－再灌注后海马CA1区神经元Bcl-2和Bcl-xL蛋白表达的抑制可能是其对短暂脑缺血产生选择性敏感的机制之一。     

Biphasic onset of splenic apoptosis following hemorrhagic shock: critical implications for Bax,Bcl-2, and Mcl-1 proteins

Introduction  

The innate immune response to trauma hemorrhage involves inflammatory mediators, thus promoting cellular dysfunction as well as cell death in diverse tissues. These effects ultimately bear the risk of post-traumatic complications such as organ dysfunction, multiple organ failure, or adult respiratory distress syndrome. In this study, a murine model of resuscitated hemorrhagic shock (HS) was used to determine the apoptosis in spleen as a marker of cellular injury and reduced immune functions.     

姜黄素对喉癌Hep-2细胞增殖及Bcl-2、Bax基因表达的影响

目的探索姜黄素对喉癌细胞增殖的作用以及对细胞Bcl-2和Bax基因表达的影响。方法 Hep-2细胞暴露于含姜黄素(3-25μM)的培养基中,分别培养24h及48h,用MTT法检测对细胞增殖的影响;用RT-PCR法检测Bcl-2和Bax的mRNA表达水平。结果 MTT显示,姜黄素使Hep-2细胞增殖明显降低,并呈时间-剂量依赖性;RT-PCR结果显示,姜黄素使Bcl-2的mRNA表达水平降低,而使Bax的mRNA表达水平升高,并呈剂量和时间依赖性。结论姜黄素对人喉癌Hep-2细胞增殖具有显著的抑制作用。其作用机制可能与其下调Bcl-2基因表达水平及上调Bax基因表达水平,从而诱导细胞凋亡有关。     

大鼠小肠缺血再灌注后氧自由基改变及肝脏Bax、Bcl-2、p53的表达

目的探讨小肠缺血再灌注后对肝组织的损伤。方法建立小肠缺血再灌注模型，分对照组，再灌注后O、30min、1h、2h、1d、3d、7d共8组，于各时点检测血中一氧化氮(N0)和超氧化物歧化酶(SOD)的浓度，用免疫组织化学SP法观察肝组织中Bax、Bcl-2、p53的表达情况。结果大鼠小肠缺血再灌注后N0浓度在再灌注Omin升高，但至再灌注2h时则明显降低，其后又持续升高，至再灌注7d时达高峰。SOD浓度在再灌注Omin明显下降，再灌注2h时升高，随后持续下降，至再灌注7d时达最低水平。再灌注Omin，肝组织中Bax、Bcl-2、p53阳性细胞率增高，再灌注30min时，Bax、Bcl-2、p53阳性细胞率升高更为明显，但Bcl-2表达明显高于Bax(P＜O．01)。再灌注2h时，3种基因均有所降低，其后又开始升高，再灌注7d时阳性细胞率达高峰，Bax表达明显高于Bcl-2(P＜O．01)。结论大鼠小肠缺血再灌注后引起血中N0和SOD的浓度变化及Bax、Bcl-2、p53阳性细胞在肝组织中的表达改变，并可能引起细胞调亡和损伤。     

Antimigratory effect of TK1-2 is mediated in part by interfering with integrin alpha2beta1

The recombinant two kringle domain of human tissue-type plasminogen activator (TK1-2) has been shown to inhibit endothelial cell proliferation, angiogenesis, and tumor cell growth despite of sharing a low amino acid sequence homology with angiostatin. Here, we explored a possible inhibitory mechanism of action of TK1-2 by focusing on antimigratory effect. TK1-2 effectively inhibited endothelial cell migration induced by basic fibroblast growth factor or vascular endothelial growth factor in a dose-dependent manner and tube formation on Matrigel. It blocked basic fibroblast growth factor-induced or vascular endothelial growth factor-induced phosphorylation of extracellular signal-regulated kinase 1/2 and formation of actin stress fibers and focal adhesions. Interestingly, TK1-2 alone induced the weak phosphorylation of focal adhesion kinase, whereas it inhibited focal adhesion kinase phosphorylation induced by growth factors. When immobilized, TK1-2 promoted adhesion and spreading of endothelial cells compared with bovine serum albumin. However, treatment with anti-alpha(2)beta(1) blocking antibody markedly diminished endothelial cell adhesion to immobilized TK1-2 compared with anti-alpha(v)beta(3) or anti-alpha(5)beta(1) antibody. Pretreatment of soluble TK1-2 also altered the binding level of anti-alpha(2)beta(1) antibody to endothelial cells in fluorescence-activated cell sorting analysis. Indeed, a blocking antibody against integrin alpha(2)beta(1) or knocking down of integrin alpha(2) expression prevented the inhibitory effect of TK1-2 in cell migration. Therefore, these results suggest that TK1-2 inhibits endothelial cell migration through inhibition of signaling and cytoskeleton rearrangement in part by interfering with integrin alpha(2)beta(1).     

高压氧对脑外伤大鼠海马神经元凋亡的影响

目的 研究高压氧对于脑外伤大鼠神经细胞凋亡的作用。方法 采用改进的Feency自Fh落体法建立脑外伤模型，72只大鼠随机分为正常对照组、脑外伤组、高压氧治疗组。在预定时间点采用TUNEL法和免疫组化法观察3组细胞的凋亡及Bcl-2和Bax蛋白表达情况。结果 高压氧治疗组伤后第1，7，24天细胞凋亡率均低于脑外伤组。各时间点Bcl-2染色阳性细胞率均高于脑外伤组，各时间点Bax染色阳性细胞率均低于脑外伤组。结论 高压氧可明显提高Bcl-2的表达，抑制Bax的表达，进而抑制细胞凋亡。     

Nitric oxide-induced apoptosis is mediated by Bax/Bcl-2 gene expression, transition of cytochrome c, and activation of caspase-3 in rat vascular smooth muscle cells

BACKGROUND: In contrast to the anti-apoptotic action of nitric oxide (NO) on endothelial cells, NO exerts a pro-apoptotic effect on vascular smooth muscle cells (VSMCs). This study was designed to elucidate the mechanism underlying NO-induced apoptosis in rat VSMCs. METHODS AND RESULTS: (1) Using the terminal deoxynucleotidyl transferase-mediated digoxigenin-11-dUTP nick end labeling (TUNEL) assay and fluorescence activated cell sorter (FACS) analyses, apoptosis of rat VSMCs were confirmed after exposure to sodium nitroprusside (SNP) (0.5 to 4 mmol/l), an exogenous NO donor. The effects of SNP were blocked by hemoglobin. (2) A universal caspase inhibitor, z-VAD-fmk, dose-dependently inhibited NO-induced apoptosis. VSMCs degraded Ac-DEVD-pNA rather than Ac-WHED-pNA after exposure to SNP, which suggested that the activation of caspase 3 rather than caspase 1 was involved in the process. Immunoblot analysis confirmed the activation of caspase-3. (3) Exposure to SNP induced the release of cytochrome c from the mitochondria to the cytosol, which was detected by immunoblot analysis of mitochondrial and cytosol fractions. (4) SNP exposure increased the ratio of Bax/Bcl-2 protein expression twofold by immunoblot analysis. CONCLUSIONS: The mechanism of NO-induced apoptosis in rat VSMCs involves an increase in the ratio of Bax/Bcl-2 gene expression, which leads to the release of cytochrome c from the mitochondria to the cytosol, finally activating caspase-3 and resultant apoptosis.     

Treatment of B-RAF mutant human tumor cells with a MEK inhibitor requires Bim and is enhanced by a BH3 mimetic

B-RAF is frequently mutated in solid tumors, resulting in activation of the MEK/ERK signaling pathway and ultimately tumor cell growth and survival. MEK inhibition in these cells results in cell cycle arrest and cytostasis. Here, we have shown that MEK inhibition also triggers limited apoptosis of human tumor cell lines with B-RAF mutations and that this effect was dependent on upregulation and dephosphorylation of the proapoptotic, Bcl-2 homology 3–only (BH3-only) Bcl-2 family member Bim. However, upregulation of Bim was insufficient for extensive apoptosis and was countered by overexpression of Bcl-2. To overcome apoptotic resistance, we treated the B-RAF mutant cells both with MEK inhibitors and with the BH3 mimetic ABT-737, resulting in profound synergism and extensive tumor cell death. This treatment was successful because of both efficient antagonism of the prosurvival Bcl-2 family member Mcl-1 by Bim and inhibition of Bcl-2 and Bcl-x_L by ABT-737. Critically, addition of ABT-737 converted the predominantly cytostatic effect of MEK inhibition to a cytotoxic effect, causing long-term tumor regression in mice xenografted with human tumor cell lines. Thus, the therapeutic efficacy of MEK inhibition requires concurrent unleashing of apoptosis by a BH3 mimetic and represents a potent combination treatment for tumors harboring B-RAF mutations.     

人参皂甙Rb1对肺缺血-再灌注损伤细胞凋亡及其调控基因表达的影响

目的:探讨人参皂甙Rb1对肺缺血再灌注(I/R)损伤细胞凋亡及其调控基因Bcl2、Bax表达的影响。方法:应用兔单肺原位热I/R模型,将24只健康家兔随机分为假手术组(S组)、I/R组及人参皂甙Rb1治疗组(Rb1组);I/R组行左肺缺血60min、再灌注120min,Rb1组在行左肺I/R前静脉给予人参皂甙Rb120mg/kg。应用末端脱氧核苷酸转移酶介导的dUTP缺口末端标记法(TUNEL)检测肺凋亡细胞,免疫组化法检测Bcl2、Bax基因表达,并利用图像分析系统进行定量分析。结果:I/R组及Rb1组细胞凋亡指数(AI)均明显高于S组(P均<0.01),Rb1组AI较I/R组明显降低(P<0.01)。I/R组及Rb1组Bcl2、Bax表达均较S组显著增加(P均<0.01),Rb1组Bcl2表达虽高于I/R组,但差异无显著性(P>0.05);Rb1组Bax表达明显低于I/R组(P<0.05)。Rb1组Bcl2/Bax比值显著高于I/R组(P<0.05),与S组较接近。结论:人参皂甙Rb1能抑制肺I/R的促凋亡基因Bax表达,但不影响抑制凋亡基因Bcl2表达的上调,可使Bcl2/Bax比值增加,从而减少细胞凋亡,减轻肺I/R损伤。     

PepT1-mediated epithelial transport of dipeptides and cephalexin is enhanced by luminal leptin in the small intestine

Dietary proteins are mostly absorbed as di- and tripeptides by the intestinal proton-dependent transporter PepT1. We have examined the effects of leptin on PepT1 function in rat jejunum and in monolayers of the human enterocyte-like 2 cell Caco-2. Leptin is produced by the stomach and secreted in the gut lumen. We show here that PepT1 and leptin receptors are expressed in Caco-2 and rat intestinal mucosal cells. Apical (but not basolateral) leptin increased Caco-2 cell transport of cephalexin (CFX) and glycylsarcosine (Gly-Sar), an effect that was associated with increased Gly-Sar uptake, increased membrane PepT1 protein, decreased intracellular PepT1 content, and no change in PepT1 mRNA levels. The maximal velocity (Vmax) for Gly-Sar transport was significantly increased by leptin, whereas the apparent Michaelis-Menten constant (Km) did not change. Furthermore, leptin-stimulated Gly-Sar transport was completely suppressed by colchicine, which disrupts cellular translocation of proteins to plasma membranes. Intrajejunal leptin also induced a rapid twofold increase in plasma CFX after jejunal perfusion with CFX in the rat, indicating enhanced intestinal absorption of CFX. These data revealed an unexpected action of gastric leptin in controlling ingestion of dietary proteins.