Tetraspanin CD9 links junctional adhesion molecule-A to αvβ3 integrin to mediate basic fibroblast growth factor–specific angiogenic signaling

Junctional adhesion molecule-A (JAM-A) is a member of the immunoglobulin family with diverse functions in epithelial cells, including cell migration, cell contact maturation, and tight junction formation. In endothelial cells, JAM-A has been implicated in basic fibroblast growth factor (bFGF)-regulated angiogenesis through incompletely understood mechanisms. In this paper, we identify tetraspanin CD9 as novel binding partner for JAM-A in endothelial cells. CD9 acts as scaffold and assembles a ternary JAM-A-CD9-αvβ3 integrin complex from which JAM-A is released upon bFGF stimulation. CD9 interacts predominantly with monomeric JAM-A, which suggests that bFGF induces signaling by triggering JAM-A dimerization. Among the two vitronectin receptors, αvβ3 and αvβ5 integrin, which have been shown to cooperate during angiogenic signaling with bFGF and vascular endothelial growth factor (VEGF), respectively, CD9 links JAM-A specifically to αvβ3 integrin. In line with this, knockdown of CD9 blocks bFGF- but not VEGF-induced ERK1/2 activation. JAM-A or CD9 knockdown impairs endothelial cell migration and tube formation. Our findings indicate that CD9 incorporates monomeric JAM-A into a complex with αvβ3 integrin, which responds to bFGF stimulation by JAM-A release to regulate mitogen-activated protein kinase (MAPK) activation, endothelial cell migration, and angiogenesis. The data also provide new mechanistic insights into the cooperativity between bFGF and αvβ3 integrin during angiogenic signaling.     

Tetraspanin CD151 Stimulates Adhesion-dependent Activation of Ras, Rac, and Cdc42 by Facilitating Molecular Association between β1 Integrins and Small GTPases

Tetraspanin CD151 associates with laminin-binding α(3)β(1)/α(6)β(1) integrins in epithelial cells and regulates adhesion-dependent signaling events. We found here that CD151 plays a role in recruiting Ras, Rac1, and Cdc42, but not Rho, to the cell membrane region, leading to the formation of α(3)β(1)/α(6)β(1) integrin-CD151-GTPases complexes. Furthermore, cell adhesion to laminin enhanced CD151 association with β(1) integrin and, thereby, increased complex formation between the β(1) family of integrins and small GTPases, Ras, Rac1, and Cdc42. Adhesion receptor complex-associated small GTPases were activated by CD151-β(1) integrin complex-stimulating adhesion events, such as α(3)β(1)/α(6)β(1) integrin-activating cell-to-laminin adhesion and homophilic CD151 interaction-generating cell-to-cell adhesion. Additionally, FAK and Src appeared to participate in this adhesion-dependent activation of small GTPases. However, engagement of laminin-binding integrins in CD151-deficient cells or CD151-specific siRNA-transfected cells did not activate these GTPases to the level of cells expressing CD151. Small GTPases activated by engagement of CD151-β(1) integrin complexes contributed to CD151-induced cell motility and MMP-9 expression in human melanoma cells. Importantly, among the four tetraspanin proteins that associate with β(1) integrin, only CD151 exhibited the ability to facilitate complex formation between the β(1) family of integrins and small GTPases and stimulate β(1) integrin-dependent activation of small GTPases. These results suggest that CD151 links α(3)β(1)/α(6)β(1) integrins to Ras, Rac1, and Cdc42 by promoting the formation of multimolecular complexes in the membrane, which leads to the up-regulation of adhesion-dependent small GTPase activation.     

Tetraspanin CD63 Promotes Vascular Endothelial Growth Factor Receptor 2-β1 Integrin Complex Formation,Thereby Regulating Activation and Downstream Signaling in Endothelial Cells in Vitro and in Vivo

CD63 is a member of the transmembrane-4 glycoprotein superfamily (tetraspanins) implicated in the regulation of membrane protein trafficking, leukocyte recruitment, and adhesion processes. We have investigated the involvement of CD63 in endothelial cell (EC) signaling downstream of β1 integrin and VEGF. We report that silencing of CD63 in primary ECs arrested capillary sprouting and tube formation in vitro because of impaired adhesion and migration of ECs. Mechanistically, CD63 associated with both β1 integrin and the main VEGF receptor on ECs, VEGFR2. Our data suggest that CD63 serves to bridge between β1 integrin and VEGFR2 because CD63 silencing disrupted VEGFR2-β1 integrin complex formation identified using proximity ligation assays. Signaling downstream of β1 integrin and VEGFR2 was attenuated in CD63-silenced cells, although their cell surface expression levels remained unaffected. CD63 was furthermore required for efficient internalization of VEGFR2 in response to VEGF. Importantly, systemic delivery of VEGF failed to potently induce VEGFR2 phosphorylation and downstream signaling in CD63-deficient mouse lungs. Taken together, our findings demonstrate a previously unrecognized role for CD63 in coordinated integrin and receptor tyrosine kinase signaling in vitro and in vivo.     

CD4+CD25+调节性T细胞

调节性T细胞(regulatory T cells,Treg)是机体维持自身耐受的重要组成部分。CD4^ CD25^ Treg细胞来源于胸腺,其主要功能是抑制自身反应性T细胞,并且其作用是通过直接的Treg-T效应细胞之间的相互接触方式来实现的。CD4^ CD25^ Treg细胞可分泌多种抑制性细胞因子,但与其抑制功能关系并不明确,目前有证据表明GITR和Foxp3与CD4^ CD25^ Treg细胞的抑制功能有关,并且Foxp3已作为CD4^ CD25^ Treg细胞的特异性标志。通过IL-10、TGF-β等抑制性细胞因子、imDC以及转基因技术可以产生具有免疫抑制功能的调节性T细胞。调节性T细胞在免疫相关性疾病、肿瘤免疫和抗感染免疫等方面具有重要意义。     

Identification of CD3ε, CD4, CD8β splice variants of Atlantic salmon

In vertebrates, CD3 complex and CD4 and CD8 co-receptors are essential for signal transduction during T cell activation. In the present study, we report the mRNA spliced variants of the Atlantic salmon CD3ε, CD4 and CD8β and the effect of pathogen encounter on the expression of these variants. CD3ε is alternatively spliced in thymus, head kidney, spleen and gills to give rise to the complete mRNA sequence and to an alternative product that lacks the transmembrane exon. CD4 is also alternatively spliced in the thymus, head kidney, spleen and gills to form two variants, although the alternative product is barely detectable. The alternative product lacks the exon 1B encoding the D1 domain, which is essential for binding to MHC class II proteins. Two amplicons were also found for the CD8β gene; sequencing analysis revealed that the main PCR product corresponds to the previously reported CD8β sequence, whereas the variant sequence encodes a potential protein that lacks the Ig-like domain. The expression of CD3, CD4, CD8β genes also analyzed in head kidney of LPS-treated and IPNV infected salmon and different patterns of expression were observed. The presence and balance of the different variants of T cell co-receptors could be related to the ability of fish to induce a particular type of immune response, as well as, the ability of the pathogen to modify the fish immune response.     

外周血CD34~＋CD33~－细胞与CD34~＋CD33~＋细胞在体外增殖与分

外周血ＣＤ３４￣＋ＣＤ３３￣－细胞与ＣＤ３４￣＋ＣＤ３３￣＋细胞在体外增殖与分化方面的区别徐娟,王惠琴,田丁（首都医科大学宣武医院血液科北京１０００５３）中村嘉彦,荒平　　（日本东海大学医学部输血中心）ＣＤ３４抗原阳性造血细胞（ＣＤ３４￣＋）具有多能...     

In Vivo Dynamical Interactions between CD4 Tregs,CD8 Tregs and CD4+CD25? Cells in Mice

Background

Regulatory T cells (Tregs) were shown to be central in maintaining immunological homeostasis and preventing the development of autoimmune diseases. Several subsets of Tregs have been identified to date; however, the dynamics of the interactions between these subsets, and their implications on their regulatory functions are yet to be elucidated.

Methodology/Principal Findings

We employed a combination of mathematical modeling and frequent in vivo measurements of several T cell subsets. Healthy BALB/c mice received a single injection of either hCDR1 - a tolerogenic peptide previously shown to induce Tregs, a control peptide or vehicle alone, and were monitored for 16 days. During this period, splenocytes from the treated mice were analyzed for the levels of CD4, CD25, CD8, CD28 and Foxp3. The collected data were then fitted to mathematical models, in order to test competing hypotheses regarding the interactions between the followed T cell subsets. In all 3 treatment groups, a significant, lasting, non-random perturbation of the immune system could be observed. Our analysis predicted the emergence of functional CD4 Tregs based on inverse oscillations of the latter and CD4⁺CD25⁻ cells. Furthermore, CD4 Tregs seemed to require a sufficiently high level of CD8 Tregs in order to become functional, while conversion was unlikely to be their major source. Our results indicated in addition that Foxp3 is not a sufficient marker for regulatory activity.

Conclusions/Significance

In this work, we unraveled the dynamics of the interplay between CD4, CD8 Tregs and effector T cells, using, for the first time, a mathematical-mechanistic perspective in the analysis of Treg kinetics. Furthermore, the results obtained from this interdisciplinary approach supported the notion that CD4 Tregs need to interact with CD8 Tregs in order to become functional. Finally, we generated predictions regarding the time-dependent function of Tregs, which can be further tested empirically in future work.     

Identification of Cytolytic CD161?CD56+ Regulatory CD8 T Cells in Human Peripheral Blood

We previously developed methods for establishing CD8 regulatory T cell (Treg) clones from normal human peripheral blood and demonstrated that these clones were capable of killing T cell receptor (TCR)-activated autologous CD4 T cells. Based on phenotypic and functional characterization of the CD8 Treg clones, we have identified a corresponding population of endogenous CD8 Treg in normal human peripheral blood. These cells appear morphologically as large lymphocytes with abundant cytoplasm and have the following unique phenotype: CD3⁺CD8⁺CD161⁻CD56⁺. The majority of CD8 Treg express CD45RA and CD62L with low or negative expression of CD45RO, CD25, CD27, CD28 and CCR7. The expression of CD94 and NKG2a on CD8 Treg was elevated compared to conventional CD8 T cells. Following in vitro activation, this T cell subset is capable of killing TCR-activated CD4 T cells. These studies identify an endogenous CD8 Treg population in humans and it will now be possible to characterize these cells in a variety of clinical conditions.     

CD40／CD40L介导信号的免疫调节作用

Ｂ细胞的ＣＤ４０分子与活化Ｔ细胞的ＣＤ４０配体（ＣＤ４０Ｌ）结合可调节Ｂ细胞生长分化、克隆转换、Ｉｇ分泌、阻断Ｂ细胞凋亡和导Ｆａｓ表面分隔表达等,直接参与调节体液免疫。ＣＤ４０与ＣＤ４０Ｌ结合也影响细胞免疫功能,诱导Ｔｈ１和Ｔｈ２细胞因子产生《ＣＤ４０和ＣＤ４０Ｌ连接ＴＲＡＦ蛋白多聚化,从而调节基因的转录。ＣＤ４０介导的信号传导过程与蛋白酷氨酸酶、蛋白酪氨酸磷酸化有等有关。     

CD147的研究进展

CD147分子是一种广泛表达于人体多种组织的跨膜糖蛋白,属于免疫球蛋白超家族。CD147在多种肿瘤细胞和组织中高表达,通过诱导基质金属蛋白酶(MMP)的分泌促进了肿瘤的浸润、转移。同时,CD147与炎症反应如类风湿性关节炎、动脉粥样硬化,以及细胞、组织的分化和发育等密切相关。简要综述了CD147参与的多种生理、病理过程。     

CD147-shRNA对胃癌细胞CD147表达的抑制作用

目的:构建CD147-shRNA重组质粒并检测其对胃癌细胞SGC7901内源性CD147表达的抑制作用。方法:构建靶向CD147的siRNA表达载体pSilencer-CD147siRNA,稳定转染至SGC7901细胞中,通过Real-time PCR和Western blot法检测转染细胞中CD147表达水平的变化。结果:酶切鉴定和测序证实成功构建pSilencer-siRNA1,pSilencer-siRNA2和pSilencer-negative,转染后SGC7901中CD147表达水平显著降,而以pSilencer-siRNA2抑制作用最为显著。结论:构建pSilencer-CD147siRNA成功,并筛选出基因抑制效果抑制最佳的pSilencer-siRNA2,为进一步实验打下了基础。     

CD4~+T、CD8~+T、CD4~+/CD8~+与慢性乙肝不同中医体质存在相关性

探讨外周血CD4~+、CD8~+T水平与慢性乙型肝炎不同中医体质的关系。选取2016年2月至2017年3月在我院治疗的慢性乙型感染患者143例,其中平和质35例、气虚质40例、阴虚质21例、湿热质20例,气郁质16例、其他11例,采用流式细胞仪检测外周血T淋巴细胞亚群。不同中医体质患者性别、年龄、病程及HBV-DNA含量比较差异无统计学意义(p0.05);平和质患者AST为342.21(142.42,513.46)U/L,明显低于其他患者(p0.05);气虚质患者AST为512.40(322.81,726.50)U/L,明显高于其他患者(p0.05);气郁质及其他体质患者ALT分别为381.64(210.41,501.72)U/L和370.43(200.41,470.63)U/L,明显高于平和质、气虚质、阴虚质和湿热质患者(p0.05);平和质和气虚质患者外周血CD4~+T细胞分别为(39.10±2.01)%和(39.10±2.01)%,明显低于阴虚质、湿热质、气郁质及其他体质患者(p0.05);气郁质及其他体质患者CD8~+T细胞分别为(25.43±1.33)%和(25.24±1.31)%,明显低于平和质、气虚质、阴虚质和湿热质患者(p0.05);阴虚质、气郁质及其他体质患者分别为(1.71±0.09)、(1.75±0.08)和(1.78±0.09),明显高于平和质、气虚质和湿热质患者(p0.05)。慢性乙肝不同中医体质与CD4~+T、CD8~+T和以及肝功能有密切关系。关键词     

紫外线照射下小鼠T细胞CD4和CD8的表达

紫外线对机体健康的影响主要有物理性损伤 ,如引起皮肤表面的红肿 ,疼痛 ,出现水泡 ,产生皱褶 ,并出现色素沉着 ,皮肤老化等现象。严重者由于紫外线对机体的光毒性作用 ,皮肤内的各种色素集团在吸收光线的同时产生大量的氧自由基 ,进而造成ＤＮＡ分子的损伤 ,引起基因突变、癌化 ,直至细胞死亡。近年来有研究报道 ,通过紫外线照射 ,抑制机体的细胞免疫机能 ,降低接触性迟发型超敏反应 ,甚至由于抑制Ｔ细胞而出现对特异性半抗原无免疫反应状态 ,但同时也使机体对细菌、寄生虫等的侵袭易感。为进一步探讨紫外线照射对机体免疫防御机能的影响 ,…     

CD40/CD40L信号系统与子痫前期的关系

子痫前期是病理产科中常见的疾病,是导致孕产妇和围生儿死亡的主要原因,其具体病因目前尚未完全阐明,大多数学者认为主要与氧化应激导致的血管内皮细胞损伤,胎盘浅着床,免疫平衡的破坏等因素有关,其中内皮细胞损伤导致的内皮细胞生理功能失衡是其病因学研究的热点.CD40/CD40L是一对互补的肿瘤坏死因子和肿瘤坏子因子受体超家族跨膜糖蛋白,相互作用可以促进内皮细胞、平滑肌细胞表达和释放细胞因子、组织因子、金属蛋白酶、粘附分子,这些物质间接或直接的参与了炎症反应和免疫调节,导致内皮细胞损伤.因此,CD40/CD40L相互作用在炎症反应和免疫失调中亦起着关键作用,可能是子痫前期的病因之一,以CD40/CD40L为靶点为子痫前期的诊断和治疗提供了新的思路和方向.本文拟对CD40/CD40L信号系统与子痫前期的关系做一综述.