大肠癌组织RhoE、p53的表达及临床意义

目的 探讨凋亡抑制蛋白RhoE、p53蛋白在大肠癌组织中的表达与不同临床病理特征的关系,以及二者在大肠癌发生过程中的相关性.方法 采用免疫组织化学法检测48例大肠癌组织和30例正常肠组织中RhoE、053蛋白的表达.结果 肠癌组织中RhoE、p53蛋白阳性表达率分别为14.58%和62.5%,较正常组织差异非常显著(P<0.01);RhoE蛋白表达与Dukes分期明显相关(P<0.01)及淋巴结转移相关(P<0.05);肠癌组织中053与RhoE蛋白表达显著负相关(P<0.01).结论 RhoE在大肠癌组织中表达下调,并与大肠癌的Dukes分期密切相关,有可能作为判断病情和评价预后的新指标;RhoE蛋白的表达与p53蛋白的表达呈负相关,提示RhoE与p53蛋白可能存在相关信号通路,有望为大肠癌基因治疗提供新的靶点.     

Rnd3表达改变对糖尿病大鼠内皮祖细胞生物学特性的影响

目的:探讨糖尿病状态下Rho家族GTP酶3(Rnd3)表达改变对骨髓源性内皮祖细胞(EPCs)一般生物学特性的影响。方法:高脂饮食联合腹腔注射链脲佐菌素建立野生型及Rnd3基因敲除杂合子(Rnd3+/-)SD大鼠糖尿病模型。建模成功后,分离、培养各组大鼠骨髓源性EPCs并鉴定。CCK-8法测定细胞活力,Western blot检测各组EPCs中凋亡相关蛋白caspase-3和Bcl-2的表达,Transwell实验测定迁移能力,ELISA检测各组细胞分泌的血管内皮生长因子(VEGF)的水平,Matrigel成管实验检测EPCs管样结构形成能力。结果:高脂饮食联合腹腔注射链脲佐菌素成功复制SD大鼠糖尿病模型。成功分离大鼠骨髓源性EPCs。糖尿病状态降低了EPCs的活力、迁移和旁分泌VEGF的能力,抑制了EPCs的Matrigel内成管能力,上述情况在Rnd3敲除后更明显。Rnd3敲除后Bcl-2水平下降而caspase-3表达上调。结论:Rnd3表达的维持对骨髓源性EPCs的增殖、迁移和血管生成等一般生物学特性具有正性调节作用。Rnd3表达不足加剧了糖尿病对EPCs一般生物学功能的损伤。     

14-3-3蛋白的研究进展

14-3-3是一个在真核生物中广泛表达的酸性蛋白家族,主要以同源/异源二聚体形式存在,通过磷酸化丝/苏氨酸作用与靶蛋白或靶蛋白的2个结构域结合。7种不同亚型的高度保守的14-3-3蛋白与人类细胞中多种不同的信号通路有密切的关系。14-3-3通过调节靶蛋白间的相互作用在信号转导途径中发挥调控作用。     

细胞自噬在Aβ_(25-35)损伤SH-SY5Y细胞中的作用

目的:探究β-淀粉样蛋白(Aβ)诱导的神经细胞损伤作用是否与调节细胞自噬相关,并基于Akt/mTOR通路对其作用机制进行初步探究。方法:5μmol/L、10μmol/L、15μmol/L、20μmol/L和25μmol/L的Aβ_(25-35)与人神经母细胞瘤SH-SY5Y细胞共同孵育24 h,MTT法检测细胞活力,Western blot检测细胞内微管相关蛋白1轻链3-I(LC3-I)、微管相关蛋白1轻链3-II(LC3-II)、Akt、p-Akt、mTOR和p-mTOR蛋白表达情况。选用合适浓度的Aβ_(25-35),观察自噬诱导剂雷帕霉素(Rapa)和自噬抑制剂3-甲基腺嘌呤(3-MA)分别与Aβ_(25-35)联用后上述指标的变化。结果:各浓度Aβ_(25-35)均能引起SH-SY5Y细胞损伤,使细胞活力下降。Aβ_(25-35)能够增加自噬标志蛋白LC3-II蛋白表达,提高LC3-II/LC3-I水平,下调Akt和mTOR蛋白磷酸化水平(P0.05)。与自噬诱导剂Rapa联用,细胞活力未见明显变化,而细胞内LC3-II蛋白表达升高,LC3-II/LC3-I明显增加,p-mTOR/mTOR明显降低(P0.05);与自噬抑制剂3-MA联用,LC3-II蛋白表达和LC3-II/LC3-I水平有下降趋势,p-Akt/Akt水平明显下降(P0.05)。结论:Aβ_(25-35)可能通过下调Akt和mTOR蛋白磷酸化水平而诱导SH-SY5Y细胞自噬状态及损伤。     

4-1BBL胞膜外区蛋白增强抗CD3/抗PgP的抗肿瘤作用

目的研究4-1BBL胞膜外区蛋白对抗CD3/抗Pgp微型双功能抗体抗肿瘤作用的影响。方法表达纯化人4-1BBL胞膜外区融合蛋白及抗CD3/抗Pgp微型双功能抗体,体外CytoTox96检测联合应用人4-1BBL胞膜外区融合蛋白、抗CD3/抗Pgp微型双功能抗体及PBL对靶细胞K562/A02细胞的杀伤作用,体内建立裸鼠移植瘤模型检测4-1BBL胞膜外区蛋白作为一种免疫调节蛋白,增强抗CD3/抗Pgp基于PBL的抗肿瘤效果。结果4-1BBL胞膜外区融合蛋白在体外能够增强抗CD3/抗Pgp及PBL对靶细胞K562/A02的杀伤作用,在体内能够增强抗CD3/抗Pgp基于PBL的抗肿瘤作用。结论可溶型4-1BBL可能成为一种有前景的生物治疗佐剂,有助于PBL更高效地靶向杀伤肿瘤细胞。     

ERK参与调节人脐动脉平滑肌细胞内SMAD2/3蛋白及其mRNA的表达

目的了解ERK信号转导通路对人脐动脉平滑肌细胞(hUASMC)内SMAD2/3蛋白及其mRNA表达的影响。方法原代培养hUASMC,实验分四组:1)对照组,2)PDGF组,3)ERK阻断剂组,4)PDGF ERK阻断剂组。分别用免疫细胞化学和RT-PCR法测hUASMC内磷酸化SMAD2/3蛋白和SMAD2/3mRNA的表达。结果1)与对照组相比,PDGF组hUASMC细胞内磷酸化SMAD2/3蛋白的表达增强(P<0·01);2)四组hUASMC细胞内SMAD2/3mRNA的表达无明显差异。结论在hUASMC中,ERK通路可促进SMAD2/3蛋白的磷酸化,但对SMAD2/3mRNA的表达没有影响。     

大鼠胚胎皮肤淋巴管血管内皮生长因子受体-3的表达

目的观察血管内皮生长因子受体-3（VEGFR-3）蛋白和mRNA在大鼠胚胎发育不同时期皮肤淋巴管内皮的表达模式,明确VEGFR-3在胚胎淋巴管发生中的生物功能.方法应用免疫组织化学技术（SABC法）和原位杂交技术对61例大鼠胚胎第15 d和第21 d皮肤组织进行VEGFR-3蛋白和mRNA检测.结果皮肤淋巴管内皮细胞阳性表达VEGFR-3蛋白和mRNA,在大鼠胚胎发育的第15 d和第21 d,VEGFR-3蛋白在淋巴管内皮的阳性表达率分别是38.71%（12/31）和73.33%（22/30）,第21 d胚胎皮肤淋巴管内皮VEGFR-3蛋白的表达水平明显高于第15d胚胎淋巴管内皮VEGFR-3蛋白的表达水平（χ^2=7.408 P〈0.01）.VEGFR-3 mRNA在淋巴管内皮的阳性表达率分别是61.29%（19/31）和80.0%（24/30）.结论1.大鼠胚胎皮肤淋巴管阳性表达VEGFR-3蛋白和VEGFR-3mRNA.2.随着大鼠胚胎的发育,VEGFR-3蛋白和mRNA在皮肤淋巴管的阳性表达均表现为上升的趋势.3.VEGFR-3在大鼠胚胎皮肤淋巴管的发育中起一定的调节作用.     

锯齿状病变组织中Runx3基因的甲基化及蛋白表达

目的探讨Runx3基因启动子区CpG岛甲基化状态和蛋白表达在锯齿状病变发生与癌变通路中的作用及意义。方法用TaqMan探针为基础的实时定量PCR(Methylight)法检测77例锯齿状病变(29例HP、29例SSA/P和19例TSA)、16例正常结直肠组织和14例结直肠癌中Runx3基因CpG岛甲基化状态,同时用免疫组化法检测相应组织中Runx3蛋白的表达;并分析两者之间的关系。结果 Runx3启动子CpG岛甲基化率在正常和HP、SSA/P、TSA、CRC分别为12.5%(2/16)和17.2%(5/29)、51.7%(15/29)、63.2%(12/19)和78.6%(11/14)。Runx3蛋白阳性表达率在正常和HP、SSA/P、TSA、CRC分别为81.3%(13/16)和72.2%(21/29)、48.3%(14/29)、31.6%(6/19)、21.4%(3/14)。SSA/P、TSA和CRC 3组中Runx3甲基化与Runx3蛋白表达结果具有相关性(P0.05),且为负相关。结论 Runx3基因启动子区域甲基化是诱导Runx3蛋白表达下调或缺失的主要原因,在锯齿状病变尤其是锯齿状腺瘤的发生及癌变通路中起重要作用。     

黄病毒多功能酶NS3研究进展

黄病毒非结构蛋白NS3是一个具有多种酶活性的蛋白,其N端为丝氨酸蛋白酶结构域,C端为RNA解旋酶/核苷三磷酸酶/RNA 5′三磷酸酶结构域。NS3在病毒前体蛋白的加工和病毒基因组的复制过程中发挥重要功能。对NS3的研究有助于新型疫苗和抗病毒药物的设计。本文试图对近年来NS3研究的进展情况进行一简要的回顾。     

磷脂酰肌醇3激酶/蛋白激酶B/雷帕霉素靶蛋白信号通路在肺部疾病中的研究进展

磷脂酰肌醇3激酶/蛋白激酶B/雷帕霉素靶蛋白(phosphatidylinositol-3-kinase/protein kinase B/mammalian target of rapamycin,PI3K/Akt/mTOR)是细胞内重要信号通路,在细胞生长、增殖、分化和蛋白合成等过程中起重要作用.肺癌、哮喘、肺动脉高压、肺纤维化、慢性阻塞性肺疾病(chronic pulmonary obstructive disease,CORD)等疾病是呼吸系统常见疾病,其病理机制涉及细胞增殖及凋亡等,与PI3K/Akt/mTOR信号通路关系密切.     

Analysis of RhoE expression in the testis,epididymis and ductus deferens,and the effects of its deficiency in mice

Rho proteins are a large family of GTPases involved in the control of actin cytoskeleton dynamics, proliferation and survival. Rnd1, Rnd2 and RhoE/Rnd3 form a subfamily of Rho proteins characterized by being constitutively active. The role of these proteins has been studied during the last years in several systems; however, little is known about their expression and functions in the reproductive organs. In this work we analysed the localization and the effect of RhoE deficiency in the testes using mice lacking RhoE expression (RhoE gt/gt), and our research shows some unexpected and relevant results. First, we have observed that RhoE is only expressed in Leydig cells within the testicular parenchyma and it is absent of seminiferous tubules. In addition, RhoE is expressed in the excurrent ducts of the testis, including the ductuli efferentes, epididymis and ductus deferens. Moreover, the testes of postnatal 15‐day‐old RhoE null mice are smaller, both in absolute values and in relation to the body weight. Furthermore, the dimensions of their seminiferous tubules are also reduced compared with wild‐types. In order to study the role of RhoE in the adult, we analysed heterozygous animals as RhoE null mice die early postnatally. Our results show that the testes of adult RhoE heterozygous mice are also smaller than those of the wild‐types, with a 17% decrease in the ratio testis weight/body weight. In addition, their seminiferous tubules have reduced tubular diameter (12%) and a thinner epithelial wall (33%) that appears disorganized and with a swollen lumen. Finally, and probably as a consequence of those alterations, the sperm concentration of heterozygous animals was found to be lower than in the wild‐types. These results indicate that accurate levels of RhoE in the testes are necessary for a correct development and function of male gonads, and suggest novel and unexpected roles of Rnd GTPases in the reproductive physiology.     

RhoE is spatiotemporally regulated in the postnatal mouse CNS

Rnd proteins are a family of small GTPases that have been involved in axon path finding and CNS development by their control of actin cytoskeleton dynamics. Rnd proteins are constitutively activated and, subsequently, their functions determined by their localization and expression levels. In this work we have analyzed by Western blot and immunohistochemistry the levels and localization of Rnd3/RhoE during mouse postnatal development. CNS was found to be the main tissue for RhoE protein expression, which was detected in all regions of the adult brain and spinal cord, with the highest levels in the olfactory bulb and cortex. RhoE protein levels were considerably higher in all the regions of the CNS the first 2–3 weeks of postnatal development, undergoing later a decrease that led to low levels in the adult. Immunohistochemical detection of RhoE at postnatal day 21 showed an intense and widespread labelling throughout the CNS. RhoE immunoreactivity was detected in the granular and mitral cells and anterior olfactory nuclei of the olfactory bulb and in all cerebral layers. In the striatum, diencephalon, mesencephalon, pons, medulla oblongata and spinal cord, RhoE was widely distributed with higher intensity in the motoneurones and in some brainstem nuclei such as the red nucleus or the reticulotegmental nucleus. The pyramidal cells of CA1-3 and the polymorph layer, but not the granular cells of the dentate gyrus in the hippocampus were strongly labelled. At earlier stages the labelling was nearly similar; however, a prominent labelling was detected in the cells of the rostral migratory stream and in the external granule cells of the cerebellum. Our results suggest that RhoE can play important roles in the postnatal development and maturation of the CNS, especially in the migratory processes affecting the neurones.     

The atypical RhoGTPase RhoE/Rnd3 is a key molecule to acquire a neuroprotective phenotype in microglia

Background

Over-activated microglia play a central role during neuroinflammation, leading to neuronal cell death and neurodegeneration. Reversion of over-activated to neuroprotective microglia phenotype could regenerate a healthy CNS-supporting microglia environment. Our aim was to identify a dataset of intracellular molecules in primary microglia that play a role in the transition of microglia to a ramified, neuroprotective phenotype.

Methods

We exploited the anti-inflammatory and neuroprotective properties of conditioned medium of adipose-derived mesenchymal stem cells (CM) as a tool to generate the neuroprotective phenotype of microglia in vitro, and we set up a microscopy-based siRNA screen to identify its hits by cell morphology.

Results

We initially assayed an array of 157 siRNAs against genes that codify proteins and factors of cytoskeleton and activation/inflammatory pathways in microglia. From them, 45 siRNAs significantly inhibited the CM-induced transition from a neurotoxic to a neuroprotective phenotype of microglia, and 50 siRNAs had the opposite effect. As a proof-of-concept, ten of these targets were validated with individual siRNAs and by downregulation of protein expression. This validation step resulted essential, because three of the potential targets were false positives. The seven validated targets were assayed in a functional screen that revealed that the atypical RhoGTPase RhoE/Rnd3 is necessary for BDNF expression and plays an essential role in controlling microglial migration.

Conclusions

Besides the identification of RhoE/Rnd3 as a novel inducer of a potential neuroprotective phenotype in microglia, we propose a list of potential targets to be further confirmed with selective activators or inhibitors.

     

Xenopus Rnd1 and Rnd3 GTP‐binding proteins are expressed under the control of segmentation clock and required for somite formation

The process of segmentation in vertebrates is described by a clock and wavefront model consisting of a Notch signal and an fibroblast growth factor‐8 (FGF8) gradient, respectively. To further investigate the segmentation process, we screened gene expression profiles for downstream targets of the segmentation clock. The Rnd1 and Rnd3 GTP‐binding proteins comprise a subgroup of the Rho GTPase family that show a specific expression pattern similar to the Notch signal component ESR5, suggesting an association between Rnd1/3 and the segmentation clock. Rnd1/3 expression patterns are disrupted by overexpression of dominant‐negative or active forms of Notch signaling genes, and responds to the FGF inhibitor SU5402 by a posterior shift analogous to other segmentation‐related genes, suggesting that Rnd1/3 expressions are regulated by the segmentation clock machinery. We also show that antisense morpholino oligonucleotides to Rnd1/3 inhibit somite segmentation and differentiation in Xenopus embryos. These results suggest that Rnd1/3 are required for Xenopus somitogenesis. Developmental Dynamics 238:2867–2876, 2009. © 2009 Wiley‐Liss, Inc.     

TGF-beta signaling-mediated morphogenesis: modulation of cell adhesion via cadherin endocytosis

The molecular mechanisms governing the cell behaviors underlying morphogenesis remain a major focus of research in both developmental biology and cancer biology. TGF-beta ligands control cell fate specification via Smad-mediated signaling. However, their ability to guide cellular morphogenesis in a variety of biological contexts is poorly understood. We report on the discovery of a novel TGF-beta signaling-mediated cellular morphogenesis occurring during vertebrate gastrulation. Activin/nodal members of the TGF-beta superfamily induce the expression of two genes regulating cell adhesion during gastrulation: Fibronectin Leucine-rich Repeat Transmembrane 3 (FLRT3), a type I transmembrane protein containing extracellular leucine-rich repeats, and the small GTPase Rnd1. FLRT3 and Rnd1 interact physically and modulate cell adhesion during embryogenesis by controlling cell surface levels of cadherin through a dynamin-dependent endocytosis pathway. Our model suggests that cell adhesion can be dynamically regulated by sequestering cadherin through internalization, and subsequent redeploying internalized cadherin to the cell surface as needed. As numerous studies have linked aberrant expression of small GTPases, adhesion molecules such as cadherins, and TGF-beta signaling to oncogenesis and metastasis, it is tempting to speculate that this FLRT3/Rnd1/cadherin pathway might also control cell behavior and morphogenesis in adult tissue homeostasis.     

Small GTPase Rnd1 is involved in neuronal activity-dependent dendritic development in hippocampal neurons

Rho family small GTPases are key regulators for neuronal morphogenesis including dendritogenesis. We recently have shown that Rnd1, a member of the Rho family, is highly expressed in brain during the synaptogenic stage and is involved in dendritic spine formation. However, the mechanism by which Rnd1 regulates dendritic development including spine morphogenesis remains unknown. Here we report that Rnd1, a member of the Rho family, plays a critical role in neuronal activity-dependent dendritic development in hippocampal neurons. Overexpression of Rnd1 promoted dendritic growth and branching in cultured hippocampal neurons. On the other hand, suppression of endogenous Rnd1 expression by RNA interference significantly inhibited neuronal activity-dependent dendritic development and this inhibitory effect was canceled by inhibition of RhoA effector ROCK. In addition, knockdown of Rnd1 also abolished dendritic development promoted by treatment with brain-derived neurotrophic factor in hippocampal neurons. Our findings demonstrate that Rnd1 is involved in signaling pathways of neuronal activity-dependent dendritic development.     

In vivo function of Rnd2 in the development of neocortical pyramidal neurons

The present study examined the in vivo role of Rnd2, a Rho family small GTPase, in brain development. Rnd2 was expressed by radially migrating cells, which primarily develop to pyramidal neurons, during their stay in the subventricular zone of embryonic cerebral cortex and hippocampus. Exogenous expression of wild-type and a constitutively active Rnd2, but not a negative mutant of Rnd2, in radially migrating cells by in utero electroporation disturbed their morphology and migration to upper layers. These results indicate that Rnd2 functions in vivo as a regulator of the migration and morphological changes associated with the development of pyramidal neurons.     

Tensor Tympani Motoneurons Receive Mostly Excitatory Synaptic Inputs

The tensor tympani is a middle ear muscle that contracts in two different situations: in response to sound or during voluntary movements. To gain insight into the inputs and neural regulation of the tensor tympani, we examined the ultrastructure of synaptic terminals on labeled tensor tympani motoneurons (TTMNs) using transmission electron microscopy. Our sample of six TTMNs received 79 synaptic terminals that formed 126 synpases. Two types of synapses are associated with round vesicles and form asymmetric junctions (excitatory morphology). One of these types has vesicles that are large and round (Lg Rnd) and the other has vesicles that are smaller and round (Sm Rnd) and also contains at least one dense core vesicle. A third synapse type has inhibitory morphology because it forms symmetric synapses with pleomorphic vesicles (Pleo). These synaptic terminals can be associated with TTMN spines. Two other types of synapse are found on TTMNs but they are uncommon. Synaptic terminals of all types form multiple synapses but those from a single terminal are always the same type. Terminals with Lg Rnd vesicles formed the most synpases per terminal (avg. 2.73). Together, the synaptic terminals with Lg Rnd and Sm Rnd vesicles account for 62% of the terminals on TTMNs, and they likely represent the pathways driving the contractions in response to sound or during voluntary movements. Having a high proportion of excitatory inputs, the TTMN innervation is like that of stapedius motoneurons but proportionately different from other types of motoneurons. Anat Rec, 2013. © 2012 Wiley Periodicals, Inc.