Current understanding of klotho

Klotho is a new anti-aging gene. Genetic mutation of klotho causes multiple premature aging-like phenotypes and strikingly shortens lifespan. Overexpression of the klotho gene in mice suppresses aging and extends lifespan which may involve the mechanism of suppression of insulin signaling and oxidant stress. Klotho functions as a cofactor/coreceptor regulating fibroblast growth factor (FGF) 23 signaling. Klotho acts as a glucuronidase and activates ion channel TRPV5. Klotho protects against endothelial dysfunction and regulates the production of nitric oxide. Klotho also influences intracellular signaling pathways including p53/p21, cAMP, protein kinase C (PKC) and Wnt signaling pathways. The discovery of klotho has a great impact on aging research. The purpose of this review is to provide the recent progress and future directions of klotho research. Specifically, this review will cover: klotho and aging, structure and expression of the klotho gene, localization of klotho expression, source of circulating klotho, current understanding of klotho functions, and signaling pathways of klotho.     

人mda-7/IL-24的抗肿瘤作用机制

mda-7/IL-24是20世纪90年代中期发现的一个新基因.由于mda-7/IL-24与人IL-10家族具有相当的同源性,后来HUGO基因命名委员会将之重新命名为IL-24,并将其归类到IL-10家族.近年研究表明,采用复制缺陷的腺病毒表达载体Ad.mda-7使其在肿瘤细胞异位表达,引起多种肿瘤细胞的生长抑制.尽管mda-7/IL-24肿瘤靶向性的作用机制还不是很清楚,但大量的实验结果表明该基因作为一个有效的肿瘤治疗基因,能够区分正常细胞和肿瘤细胞、诱导各种不同肿瘤细胞凋亡、启动抗肿瘤"旁观者效应"、增强肿瘤细胞对射线敏感性、抑制动物模型体内移植瘤的生长和血管新生以及具有调节免疫应答能力.     

上皮间质转化与肿瘤侵袭转移关系的研究进展

上皮间质转化(epithelial-mesenchymal transition,EMT)是指上皮细胞失去极性,失去与基底膜的连接等上皮表型,通过特定程序转化为具有间质表型的生物学过程,从而获得了较高的迁移与侵袭、抗凋亡和降解细胞外基质的能力,与肿瘤的侵袭转移密切相关。参与这一过程的细胞内信号转导途径主要有:TGF-β信号途径、PI3K/AKT途径、Notch信号通路、Wnt信号通路等。本文就EMT在肿瘤侵袭转移中的作用及其分子机制的研究作一综述。     

RNA干扰Hedgehog信号通路对胃癌细胞增殖和凋亡影响及其机制的探讨

目的:观察RNA干扰Hedgehog信号通路关键因子Glil对胃癌细胞的生物学行为的影响并分析相关机制.方法:人工合成靶向Hedgehog信号通路活化关键因子Glil的siRNA(Glil siRNA)和对照无关siRNA(Con siRNA),应用脂质体将其转入人胃癌细胞SGC-7901,48 h后收集细胞,分别应用MTT法和流式细胞仪检测对细胞增殖、周期和凋亡的影响,同时应用TaqMan探针实时定量PCR检测靶基因Glil、Hedgehog活化标志基因PTCH1、细胞周期负调控蛋白基因CDKN1A(p21)和抗凋亡基因Bel-2的表达变化.结果:以单纯转染剂对照组为参照,siRNA转染后48 h,Glil siRNA和Con siRNA的抑制率分别为(53.33±6.06)%和(13.33±6.11)%,两组差异有统计学意义,t=5.701,P=0.005,n=3;G0/G1期分别为(80.67±4.51)%和(66.00±3.10)%,两组差异有统计学意义,t=5.500,P=0.005,n=3;凋亡率分别为(15.97±1.76)%和(7.77±1.11)%,两组差异有统计学意义,t=4.671,P=0.01,n=3;GlilsiRNA转染细胞内Glil、PTCH1、Bcl-2和CDKN1A(p21)基因的相对(参照单纯转染剂)表达分别为对照的0.24±0.11、0.43±0.09、0.52±0.13和2.10±0.30.分别与Con siRNA相比4条基因表达均差异有统计学意义,t=9.759,P=0.001,n=3;t=8.645,P=0.001,n=3;t=4.940,P=0.008,n=3;t=5.962,P=0.004,n=3.结论:应用RNA干扰技术可以阻断Hedgehog信号通路关键因子Glil的表达,抑制Hedgehog信号通路活化,从而有效地抑制胃癌细胞的增长,诱导凋亡,可能成为治疗胃癌新的生物靶向治疗途径.     

小胶质细胞在肠易激综合征大鼠内脏敏化中的作用

目的观察阻断小胶质细胞的MAPK-p38信号通路对肠易激综合征(intestinal bowel syndrome,IBS)大鼠内脏敏感性的影响,为探讨IBS内脏敏化的神经机制提供理论依据。方法 30只昆明鼠用旋毛虫灌胃的方法成功制作IBS模型,随机分为Ⅰ和Ⅱ两个大组,各组再随机分为3个亚组:生理盐水IBS对照组、单纯IBS组、SB203580组,每组5只。IBS大鼠通过脊髓插管给予小胶质细胞信号转导途径MAPK-p38的特异性阻断剂SB203580干预小胶质细胞的功能。Ⅰ组用于观察痛行为学积分、腹直肌肌电以及小胶质细胞活化情况。Ⅱ组再取5只大鼠作为空白对照组,用于测定骶髓DCN单位放电。结果 SB203580组的痛行为学积分、腹直肌肌电反应变化(频率、振幅)和小胶质细胞活化程度OD值显著低于脊髓插管给予生理盐水IBS对照组、单纯IBS组(P<0.05)。脊髓插管给予SB203580组DCN的单位放电频率显著低于脊髓插管给予生理盐水IBS对照组、单纯IBS组(P<0.05),但高于空白对照组DCN的单位放电频率,差异有统计学意义(P<0.05)。结论小胶质细胞参与了IBS大鼠的内脏敏化反应,当其细胞信号转导途径被阻断,即可明显阻断后续疼痛反应的发生,提示小胶质细胞在IBS内脏敏化中发挥重要作用,该反应可能是通过细胞信号转导途径P38实现的。     

Janus激酶-信号转导子与转录激活子信号通路在硫化氢后处理离体缺血再灌注大鼠心肌中的作用

目的 探讨Janus激酶-信号转导子与转录激活子(JAK2/STAT3)信号通路在硫化氢后处理(H2S)减轻离体大鼠心脏缺血/再灌注(I/R)损伤的作用.方法 应用Langendorff离体心脏灌流装置、通过停灌30 min/复灌60 min的方法建立SD大鼠I/R模型.按照处理及再灌注成分分为持续灌注对照组,I/R组...     

Role of regulators of g-protein signaling 4 in ca signaling in mouse pancreatic acinar cells

Regulators of G-protein signaling (RGS) proteins are regulators of Ca(2+) signaling that accelerate the GTPase activity of the G-protein α-subunit. RGS1, RGS2, RGS4, and RGS16 are expressed in the pancreas, and RGS2 regulates G-protein coupled receptor (GPCR)-induced Ca(2+) oscillations. However, the role of RGS4 in Ca(2+) signaling in pancreatic acinar cells is unknown. In this study, we investigated the mechanism of GPCR-induced Ca(2+) signaling in pancreatic acinar cells derived from RGS4(-/-) mice. RGS4(-/-) acinar cells showed an enhanced stimulus intensity response to a muscarinic receptor agonist in pancreatic acinar cells. Moreover, deletion of RGS4 increased the frequency of Ca(2+) oscillations. RGS4(-/-) cells also showed increased expression of sarco/endoplasmic reticulum Ca(2+) ATPase type 2. However, there were no significant alterations, such as Ca(2+) signaling in treated high dose of agonist and its related amylase secretion activity, in acinar cells from RGS4(-/-) mice. These results indicate that RGS4 protein regulates Ca(2+) signaling in mouse pancreatic acinar cells.