Cell migration: Rho GTPases lead the way

Rho GTPases control signal transduction pathways that link cell surface receptors to a variety of intracellular responses. They are best known as regulators of the actin cytoskeleton, but in addition they control cell polarity, gene expression, microtubule dynamics and vesicular trafficking. Through these diverse functions, Rho GTPases influence many aspects of cell behavior. This review will focus specifically on their role in cell migration.     

The Scribble Cell Polarity Module in the Regulation of Cell Signaling in Tissue Development and Tumorigenesis

The Scribble cell polarity module, comprising Scribbled (Scrib), Discs-large (Dlg) and Lethal-2-giant larvae (Lgl), has a tumor suppressive role in mammalian epithelial cancers. The Scribble module proteins play key functions in the establishment and maintenance of different modes of cell polarity, as well as in the control of tissue growth, differentiation and directed cell migration, and therefore are major regulators of tissue development and homeostasis. Whilst molecular details are known regarding the roles of Scribble module proteins in cell polarity regulation, their precise mode of action in the regulation of other key cellular processes remains enigmatic. An accumulating body of evidence indicates that Scribble module proteins play scaffolding roles in the control of various signaling pathways, which are linked to the control of tissue growth, differentiation and cell migration. Multiple Scrib, Dlg and Lgl interacting proteins have been discovered, which are involved in diverse processes, however many function in the regulation of cellular signaling. Herein, we review the components of the Scrib, Dlg and Lgl protein interactomes, and focus on the mechanism by which they regulate cellular signaling pathways in metazoans, and how their disruption leads to cancer.     

细胞打印技术及应用

细胞打印技术是一种在体外构造具有生物活性的三维多细胞体系的先进技术。近年来,有关细胞打印技术的研究引起广泛的关注,其原因在于该领域具有明显的学科交叉与渗透融合的特点,它处于生命科学与快速成型技术、生物制造技术、生物科学和材料科学的交汇点。更加值得关注的是它为组织工程学突破二维研究的局限性,在三维尺度上精确控制与人体组织或器官相似的三维构造体方面的研究提供了一种新的思路。基于这一技术不仅在三维组织工程,还对细胞生物学、高通量药物筛选及细胞传感器等方面的前沿问题均有广阔的研究应用前景,介绍了近年来开发用于细胞打印的技术及其潜在的应用。     

Distinguishing between Directed and Undirected Cell Motility within an Invading Cell Population

Cell invasion is the basis of several fundamental biological systems including developmental morphogenesis and disease progression. Invasion processes involve combined cell motility and proliferation. Standard experimental approaches to characterize invasion systems focus on measuring population-level wavespeed data. However, continuum models which incorporate either directed or undirected motility both give rise to traveling wave solutions with a well-defined wavespeed in terms of the motility parameters. Therefore, such population-level models and experimental data cannot be used to determine whether the motility is directed or undirected. This is a major impediment limiting our ability to interpret experimental observations of cell invasion. We demonstrate how to overcome this difficulty using individual-level data and discrete models. This approach can be used to interpret and design time-lapse imaging data to determine whether the cell motility is directed or undirected. Making a distinction between directed and undirected motility has profound implications regarding our ability to design strategies to manage development and disease associated with cell invasion. The authors gratefully acknowledge the support from the Australian Research Council (ARC) Discovery Project DP0662804. MS is an ARC postdoctoral fellow, KL is an ARC professorial fellow.     

基于微系统技术的细胞微操控、细胞图形化方法及应用

微系统技术给细胞研究提供了一个全新的平台。细胞图形化（Cell Patterning）技术作为全新的细胞培养方式,在细胞研究中发挥重要作用。本文介绍了目前应用于细胞图形化的主要技术,包括光刻（Photolithography）、软光刻（Soft lithography）、模板辅助（Stencil-assisted patterning）等方法,并阐述了利用细胞图形化技术的在基础生物学、组织工程以及基于细胞的生物传感器等方面的主要应用。     

细胞药物的种类及生物学特性——细胞药物连载之一

细胞药物是以不同细胞为基础的用于疾病治疗的制剂、药物或产品的统称,是继放疗、化疗之后又一种临床有效的治疗手段,可实施个性化治疗。细胞药物的种类很多,按其生物学特性可分为传统体细胞、免疫细胞以及各种不同的干细胞等。经体外操作过的细胞群,如肝细胞、胰岛细胞、软骨细胞、树突状细胞、细胞因子诱导的杀伤细胞、淋巴因子激活的杀伤细胞、体外加工的骨髓或造血干细胞和体外处理的肿瘤细胞(瘤苗)等。细胞药物已在一些难治性疾病中得到应用,包括血液系统疾病、心血管系统疾病、消化系统疾病、神经系统疾病、免疫系统疾病和抗衰老等。细胞治疗涉及的细胞种类很多,且不同细胞或不同治疗方法各有特点。运用不同的细胞药物来修复病变细胞,以重建受损的功能细胞和组织,恢复其生物学功能,为细胞丢失或损伤性疾病的防治提供了崭新的思路。     

Myocilin Regulates Cell Proliferation and Survival

Myocilin, a causative gene for open angle glaucoma, encodes a secreted glycoprotein with poorly understood functions. To gain insight into its functions, we produced a stably transfected HEK293 cell line expressing myocilin under an inducible promoter and compared gene expression profiles between myocilin-expressing and vector control cell lines by a microarray analysis. A significant fraction of differentially expressed genes in myocilin-expressing cells was associated with cell growth and cell death, suggesting that myocilin may have a role in the regulation of cell growth and survival. Increased proliferation of myocilin-expressing cells was demonstrated by the WST-1 proliferation assay, direct cell counting, and immunostaining with antibodies against Ki-67, a cellular proliferation marker. Myocilin-containing conditioned medium also increased proliferation of unmodified HEK293 cells. Myocilin-expressing cells were more resistant to serum starvation-induced apoptosis than control cells. TUNEL-positive apoptotic cells were dramatically decreased, and two apoptotic marker proteins, cleaved caspase 7 and cleaved poly(ADP-ribose) polymerase, were significantly reduced in myocilin-expressing cells as compared with control cells under apoptotic conditions. In addition, myocilin-deficient mesenchymal stem cells exhibited reduced proliferation and enhanced susceptibility to serum starvation-induced apoptosis as compared with wild-type mesenchymal stem cells. Phosphorylation of ERK1/2 and its upstream kinases, c-Raf and MEK, was increased in myocilin-expressing cells compared with control cells. Elevated phosphorylation of ERK1/2 was also observed in the trabecular meshwork of transgenic mice expressing 6-fold higher levels of myocilin when compared with their wild-type littermates. These results suggest that myocilin promotes cell proliferation and resistance to apoptosis via the ERK1/2 MAPK signaling pathway.     

NAIF1对肝癌细胞 HepG2 增殖与迁移能力的影响

目的:在肝癌细胞Hep G2中过表达外源NAIF1(核凋亡诱导因子1),探讨NAIF1的亚细胞定位以及对Hep G2增殖和迁移能力的影响。方法:以真核表达质粒p EGFP-N1为对照组,p EGFP-N1-NAIF1为实验组,瞬时转染肝癌细胞Hep G2,利用免疫印迹方法检测NAIF1蛋白表达效率;以DAPI染核,荧光显微镜下观察绿色荧光蛋白定位,确定NAIF1的亚细胞定位;通过MTT方法绘制细胞增殖曲线;通过transwell小室法检测NAIF1对Hep G2迁移能力的影响。结果:在肝癌细胞Hep G2中,外源表达NAIF1主要定位于细胞核;与对照组Hep G2/p EGFP-N1相比,Hep G2/p EGFP-N1-NAIF1的细胞增殖、迁移能力下降(P<0.05)。结论:外源表达NAIF1蛋白定位于Hep G2细胞核,过表达NAIF1抑制Hep G2的细胞增殖与迁移能力,NAIF1可能作为肝癌治疗的潜在靶点。     

Rab23 在鳞癌细胞系中的表达及其对鳞癌细胞侵袭的影响*

目的:观察Rab23在鳞癌细胞系中的表达及其对鳞癌细胞侵袭的影响。方法:western blot检测Rab23在四个头颈部鳞癌细胞系中的表达,对鳞癌细胞系HSQ-89用脂质体转染小干扰RNA,对Sa3用脂质体转染Rab23质粒,分别干涉或过表达Rab23,用铺有基质胶的transwell小室检测细胞侵袭能力,细胞划痕试验检测迁移能力。结果:Rab23在四个鳞癌细胞系中均有表达,在Hacat中不表达,HSQ-89细胞经Rab23干涉后细胞侵袭能力减弱,而Sa-3细胞过表达Rab23后细胞侵袭能力增强。干涉或过表达Rab23后,鳞癌细胞的迁移能力无差异。结论:Rab23可促进鳞癌细胞侵袭。     

Synergistic Effects of Interleukin-7 and Pre-T Cell Receptor Signaling in Human T Cell Development

The role of IL-7 in pre-T cell receptor (TCR) signaling during human T cell development is poorly understood. To study this, we engineered Molt3, a T cell progenitor T-acute lymphoblastic leukemia cell line, using lentiviral IL-7 receptor α (IL-7Rα) to serve as a model system. IL-7 promoted pre-TCR activation in IL-7Rα^hi Molt3 as illustrated by CD25 up-regulation after anti-CD3 stimulation. Anti-CD3 treatment activated Akt and Erk1/2 signaling pathways as proven using specific inhibitors, and IL-7 further enhanced both signaling pathways. The close association of IL-7Rα with CD3ζ in the pre-TCR complex was illustrated through live imaging confocal fluorescence microscopy. These results demonstrate a direct and cooperative role of IL-7 in pre-TCR signaling.     

家蝇抗菌肽对细菌细胞表面特性影响及其作用机理的研究

利用微生物对十六烷吸附的方法(MATS方法)、微电泳方法与测定细菌质膜上β-半乳糖苷酶活性的方法,探讨了家蝇抗菌肽对大肠杆菌等6种细菌细胞表面特性及其细胞膜的作用机制。研究结果表明,抗菌肽使细菌表面电负性增强,对G 细菌细胞表面电荷的改变大于对G-的改变,使细菌细胞表面疏水性不同程度的下降。抗菌肽引起细菌细胞膜通透性迅速增加,不同细菌β-半乳糖苷酶释放的最大速度VP在3.86pmol/min～6.92pmol/min,相应的时间TP为0,由此推测抗菌肽对细胞膜的作用机制是“形成孔洞”。     

细胞壁在细胞极性建立和胚胎发生中的作用

植物细胞壁是一个活性的动态结构,其结构层次与组分随着发育进程而发生变化,且广泛参与细胞的各项生命活动,特别是在参与细胞命运决定、充当细胞发育信使、调控植物胚胎早期极性建立以及模式建成等方面发挥重要作用。     

植物细胞胞内产物释放行为研究进展

本文介绍了植物细胞培养中胞内产物释放的研究现状,包括：１、化学法：（１）有机溶剂法,（２）抗生素法,（３）蛋白质、溶血卵磷脂、脱乙酰几丁质,（４）去污剂、螯合剂;２、物理法：（１）渗透压冲击,（２）温度冲击,（３）电处理,（４）超声波处理、激光打孔,３、ｐＨ扰动及生物碱在胞内积累的两种机理 。     

Cell proliferation drives neural crest cell invasion of the intestine

A general mathematical model of cell invasion is developed and validated with an experimental system. The model incorporates two basic cell functions: non-directed (diffusive) motility and proliferation to a carrying capacity limit. The model is used here to investigate cell proliferation and motility differences along the axis of an invasion wave. Mathematical simulations yield surprising and counterintuitive predictions. In this general scenario, cells at the invasive front are proliferative and migrate into previously unoccupied tissues while those behind the front are essentially nonproliferative and do not directly migrate into unoccupied tissues. These differences are not innate to the cells, but are a function of proximity to uninvaded tissue. Therefore, proliferation at the invading front is the critical mechanism driving apparently directed invasion. An appropriate system to experimentally validate these predictions is the directional invasion and colonization of the gut by vagal neural crest cells that establish the enteric nervous system. An assay using gut organ culture with chick-quail grafting is used for this purpose. The experimental results are entirely concordant with the mathematical predictions. We conclude that proliferation at the wavefront is a key mechanism driving the invasive process. This has important implications not just for the neural crest, but for other invasion systems such as epidermal wound healing, carcinoma invasion and other developmental cell migrations.     

Modelling the Cell Cycle and Cell Movement in Multicellular Tumour Spheroids

This paper analyses a recent mathematical model of avascular tumour spheroid growth which accounts for both cell cycle dynamics and chemotactic driven cell movement. The model considers cells to exist in one of two compartments: proliferating and quiescent, as well as accounting for necrosis and apoptosis. One particular focus of this paper is the behaviour created when proliferating and quiescent cells have different chemotactic responses to an extracellular nutrient supply. Two very different steady-state behaviours are identified corresponding to those cases where proliferating cells move either more quickly or more slowly than quiescent cells in response to a gradient in the extracellular nutrient supply. The case where proliferating cells move more rapidly leads to the commonly accepted spheroid structure of a thin layer of proliferating cells surrounding an inner quiescent core. In the case where proliferating cells move more slowly than quiescent cells the model predicts an interesting structure of a thin layer of quiescent cells surrounding an inner core of proliferating and quiescent cells. The sensitivity of this tumour structure to the cell cycle model parameters is also discussed. In particular variations in the steady-state size of the tumour and the types of transient behaviour are explored. The model reveals interesting transient behaviour with sharply delineated regions of proliferating and quiescent cells.     

植物细胞电融合技术在空间实验中的应用

细胞电融合是实用性很强的生物技术,然而在地面上由于重力沉降和热对流的影响,杂种细胞融合得率较低,使得这项技术在生产上的应用潜力难以发挥。大量的实验表明,空间微重力环境是实现细胞电融合的重要途径。今后有望利用空间微重力条件获得有价值的杂合细胞,培育作物新品种,为开展空间生物加工和空间制药提供良好基础。