CD147 stimulates HIV-1 infection in a signal-independent fashion

CD147 is a type I transmembrane protein previously identified as a signal transducing receptor for extracellular cyclophilins. CD147-expressing cells exhibit a characteristic activation of extracellular-signal regulated kinase 1 and 2 (ERK1/2) in response to stimulation with cyclophilin A (CypA). CD147 was also shown to enhance HIV-1 infection in a CypA-dependent fashion, but the role of signaling in this activity of CD147 has not been investigated. In this report, we demonstrate that neither mutations incapacitating signaling response of CD147 to CypA stimulation, nor inhibitor of ERK activation, reduced susceptibility of cells to HIV-1 infection. Surprisingly, truncation of the cytoplasmic tail of CD147 did not abolish signaling response to CypA, but reduced infection by HIV-1 to the level observed in control cells. These results indicate that CD147 enhances HIV-1 replication in a signaling-independent fashion through specific events mediated by the cytoplasmic domain of the protein.     

Cell surface expression of CD147/EMMPRIN is regulated by cyclophilin 60

CD147, also known as extracellular matrix metalloproteinase inducer, is a regulator of matrix metalloproteinase production and also serves as a signaling receptor for extracellular cyclophilins. Previously, we demonstrated that cell surface expression of CD147 is sensitive to cyclophilin-binding drug cyclosporin A, suggesting involvement of a cyclophilin in the regulation of intracellular transport of CD147. In this report, we identify this cyclophilin as cyclophilin 60 (Cyp60), a distinct member of the cyclophilin family of proteins. CD147 co-immunoprecipitated with Cyp60, and confocal immunofluorescent microscopy revealed intracellular co-localization of Cyp60 and CD147. This interaction with Cyp60 involved proline 211 of CD147, which was shown previously to be critical for interaction between CD147 and another cyclophilin, cyclophilin A, in solution. Mutation of this proline residue abrogated co-immunoprecipitation of CD147 and Cyp60 and reduced surface expression of CD147 on the plasma membrane. Suppression of Cyp60 expression using RNA interference had an effect similar to that of cyclosporin A: reduction of cell surface expression of CD147. These results suggest that Cyp60 plays an important role in the translocation of CD147 to the cell surface. Therefore, Cyp60 may present a novel target for therapeutic interventions in diseases where CD147 functions as a pathogenic factor, such as cancer, human immunodeficiency virus infection, or rheumatoid arthritis.     

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与亲环蛋白的相互作用

CD147是一种属于免疫球蛋白超家族的跨膜糖蛋白,可参与多种生理和病理过程,在组织重构、精子发生、神经形成及肿瘤转移等过程中发挥作用,其高表达于某些免疫细胞和肿瘤细胞表面,作为受体可与亲环蛋白(Cyp)结合。Cyp遍布于原核及真核生物中,在人类正常和肿瘤组织中,均可发现亲环蛋白。CypA和CypB这两种亲环蛋白家族中最丰富的成员,在细胞内和细胞外均可发挥重要作用。亲环蛋白与CD147的相互作用在炎症性疾病、心血管疾病及肿瘤的发生发展中具有重要意义,本文对CD147和亲环蛋白这两种蛋白质及其相互作用的研究进展和前景做一综述。     

Active site residues of cyclophilin A are crucial for its signaling activity via CD147

Cyclophilin A (CyPA), a ubiquitously distributed intracellular protein, is a peptidylprolyl cis-trans-isomerase and the major target of the potent immunosuppressive drug cyclosporin A. Although expressed predominantly as an intracellular molecule, CyPA is secreted by cells in response to inflammatory stimuli and is a potent neutrophil and eosinophil chemoattractant in vitro and in vivo. The mechanisms underlying CyPA-mediated signaling and chemotaxis are unknown. Here, we identified CD147 as a cell surface receptor for CyPA and demonstrated that CD147 is an essential component in the CyPA-initiated signaling cascade that culminates in ERK activation. Both signaling and chemotactic activities of CyPA depended also on the presence of heparans, which served as primary binding sites for CyPA on target cells. The proline 180 and glycine 181 residues in the extracellular domain of CD147 were critical for signaling and chemotactic activities mediated by CD147. Also crucial were active site residues of CyPA, because rotamase-defective CyPA mutants failed to initiate signaling events. These results establish cyclophilins as natural ligands for CD147 and suggest an unusual, rotamase-dependent mechanism of signaling.     

CD147 is a signaling receptor for cyclophilin B.

Cyclophilins A and B (CyPA and CyPB) are cyclosporin A binding proteins that can be secreted in response to inflammatory stimuli. We recently identified CD147 as a cell-surface receptor for CyPA and demonstrated that CD147 is an essential component in the CyPA-initiated signaling cascade that culminates in ERK activation and chemotaxis. Here we demonstrate that CD147 also serves as a receptor for CyPB. CyPB induced Ca(2+) flux and chemotaxis of CD147-transfected, but not control, CHO cells, and the chemotactic response of primary human neutrophils to CyPB was blocked by antibodies to CD147. These results suggest that CD147 serves as a receptor for extracellular cyclophilins.     

Solution Characterization of the Extracellular Region of CD147 and Its Interaction with Its Enzyme Ligand Cyclophilin A

The CD147 receptor plays an integral role in numerous diseases by stimulating the expression of several protein families and serving as the receptor for extracellular cyclophilins; however, neither CD147 nor its interactions with its cyclophilin ligands have been well characterized in solution. CD147 is a unique protein in that it can function both at the cell membrane and after being released from cells where it continues to retain activity. Thus, the CD147 receptor functions through at least two mechanisms that include both cyclophilin-independent and cyclophilin-dependent modes of action. In regard to CD147 cyclophilin-independent activity, CD147 homophilic interactions are thought to underlie its activity. In regard to CD147 cyclophilin-dependent activity, cyclophilin/CD147 interactions may represent a novel means of signaling since cyclophilins are also peptidyl-prolyl isomerases. However, direct evidence of catalysis has not been shown within the cyclophilin/CD147 complex. In this report, we have characterized the solution behavior of the two most prevalent CD147 extracellular isoforms through biochemical methods that include gel-filtration and native gel analysis as well as directly through multiple NMR methods. All methods indicate that the extracellular immunoglobulin-like domains are monomeric in solution and, thus, suggest that CD147 homophilic interactions in vivo are mediated through other partners. Additionally, using multiple NMR techniques, we have identified and characterized the cyclophilin target site on CD147 and have shown for the first time that CD147 is also a substrate of its primary cyclophilin enzyme ligand, cyclophilin A.     

CD147与炎症性疾病的关系

免疫球蛋白超家族的跨膜蛋白(CD147/basigin)的主要作用是通过诱导基质金属蛋白酶(matrix metalloproteinase,MMP)的产生来促进基质的降解,在多种肿瘤中高表达,也参与多种炎症性疾病的发生发展。本文就CD147与炎症性疾病关系的研究进展做一综述。     

CD147相互作用蛋白及其细胞生物学功能

CD147（basigin、EMMPRIN、neurothelin、M6、HAb18G等）是一个跨膜糖蛋白家族,广泛表达于各种上皮细胞,但其表达在大鼠、小鼠、鸡和人等不同种属间存在很大差异性。CD147高表达于上皮来源的肿瘤细胞表面,如肺癌、乳腺癌和肝癌等。CD147抗原胞外段有2个IgSF结构域,跨膜区有一个带电谷氨酸（GIu）残基,胞内段含有40个氨基酸。CD147的结构特点提示其可能参与蛋白-蛋白相互作用。由于CD147分子的3D结构信息还没有获得,与其相互作用的分子还没有完全明确,但近来应用黏附、免疫共沉淀等实验方法,一些研究报道提示,CD147可与整合素（integrin）、环亲合素（cyclophilins）、单羧酸转运器（monocarboxylate transporter,MCT）等蛋白相互作用,而这些蛋白可能作为CD147分子的候选配体或受体,通过蛋白-蛋白相互作用,介导广泛的上皮细胞生物学功能。     

Metabolic activation-related CD147-CD98 complex

Cell surface CD147 protein promotes production of matrix metalloproteinases and hyaluronan, associates with monocarboxylate transporters and integrins, and is involved in reproductive, neural, inflammatory, and tumor functions. Here we combined covalent cross-linking, mass spectrometric protein identification, and co-immunoprecipitation to show selective CD147 association with three major types of transporters (CD98 heavy chain (CD98hc)-L-type amino acid transporter, ASCT2, and monocarboxylate transporters) as well as a regulator of cell proliferation (epithelial cell adhesion molecule). In the assembly of these multicomponent complexes, CD147 and CD98hc play a central organizing role. RNA interference knock-down experiments established a strong connection between CD147 and CD98hc expression and a strong positive association of CD147 (and CD98hc) with cell proliferation. As the CD147-CD98hc complex and proliferation diminished, AMP-activated protein kinase (a cellular "fuel gauge") became activated, indicating a disturbance of cellular energy metabolism. Our data point to a CD147-CD98 cell surface supercomplex that plays a critical role in energy metabolism, likely by coordinating transport of lactate and amino acids. Furthermore we showed how covalent cross-linking, together with mass spectrometry, can be used to identify closely associated transmembrane proteins. This approach should also be applicable to many other types of transmembrane proteins besides those associated with CD98hc and CD147.     

Novel approach to inhibit asthma-mediated lung inflammation using anti-CD147 intervention

Extracellular cyclophilins have been well described as chemotactic factors for various leukocyte subsets. This chemotactic capacity is dependent upon interaction of cyclophilins with the cell surface signaling receptor CD147. Elevated levels of extracellular cyclophilins have been documented in several inflammatory diseases. We propose that extracellular cyclophilins, via interaction with CD147, may contribute to the recruitment of leukocytes from the periphery into tissues during inflammatory responses. In this study, we examined whether extracellular cyclophilin-CD147 interactions might influence leukocyte recruitment in the inflammatory disease allergic asthma. Using a mouse model of asthmatic inflammation, we show that 1) extracellular cyclophilins are elevated in the airways of asthmatic mice; 2) mouse eosinophils and CD4+ T cells express CD147, which is up-regulated on CD4+ T cells upon activation; 3) cyclophilins induce CD147-dependent chemotaxis of activated CD4+ T cells in vitro; 4) in vivo treatment with anti-CD147 mAb significantly reduces (by up to 50%) the accumulation of eosinophils and effector/memory CD4+ T lymphocytes, as well as Ag-specific Th2 cytokine secretion, in lung tissues; and 5) anti-CD147 treatment significantly reduces airway epithelial mucin production and bronchial hyperreactivity to methacholine challenge. These findings provide a novel mechanism whereby asthmatic lung inflammation may be reduced by targeting cyclophilin-CD147 interactions.     

CD147 depletion down-regulates matrix metalloproteinase-11, vascular endothelial growth factor-A expression and the lymphatic metastasis potential of murine hepatocarcinoma Hca-F cells

Extracellular matrix metalloproteinase inducer (EMMPRIN, CD147), which is a plasma membrane glycoprotein enriched on the surface of many malignant tumors promotes adhesion, invasion and metastasis of tumor cells. In addition, tumor-associated CD147 also induces vascular endothelial growth factors (VEGFs) expression. To investigate the possible role of CD147 in the mouse hepatocarcinoma cell line Hca-F with highly metastatic potential in the lymph nodes, we used an RNA interference (RNAi) approach to silence CD147 expression. The results showed that CD147 depletion in Hca-F cells resulted in the significantly decreased expression of matrix metalloproteinase-11 (MMP-11), VEGF-A at both mRNA and protein levels. The reduced CD147 expression also attenuated the invasive, adhesive, metastatic ability of Hca-F cells to lymph nodes both in vitro and in vivo. Our current findings reveal that the tumor biological marker CD147 functionally mediates MMP-11, VEGF-A expression and tumor lymphatic metastasis.     

细胞外基质金属蛋白酶诱导分子(CD147)在胰腺癌细胞及胰腺星状细胞中的表达(英文)

目的:探讨细胞外基质金属蛋白酶诱导分子(CD147)在胰腺癌细胞(Panc-1)及胰腺星状细胞(PSCs)的表达。方法:应用QRT-PCR,免疫细胞化学和免疫印迹分析方法检测Panc-1和PSCs细胞中EMMRPIN的表达,应用脱糖基化试剂N-glycosidase F及Endoglycosidase H鉴定CD147糖基化形式。结果:CD147在Panc-1和PSCs细胞质膜及细胞质中高表达,通过脱糖基化法首次鉴定出胰腺癌细胞及胰腺星状细胞中CD147不同的糖基化修饰。结论:CD147的糖基化修饰具有细胞特异性,可能与细胞恶性程度相关。     

细胞外基质金属蛋白酶诱导分子（CD147）在胰腺癌细胞及胰腺星状细胞中的表达

目的：探讨细胞外基质金属蛋白酶诱导分子（CD147）在胰腺癌细胞（Panc-1）及胰腺星状细胞（PSCs）的表达。方法：应用QRT—PCR,免疫细胞化学和免疫印迹分析方法检测Panc-1和PSCs细胞中EMMRPIN的表达,应用脱糖基化试剂N—glycosidase F及Endoglycosidase H鉴定CD147糖基化形式。结果：CD147在Panc-1和PSCs细胞质膜及细胞质中高表达,通过脱糖基化法首次鉴定出胰腺癌细胞及胰腺星状细胞中CD147不同的糖基化修饰。结论：CD147的糖基化修饰具有细胞特异性,可能与细胞恶性程度相关。     

癌相关分子CD147与肝癌靶向治疗

CD147是一种在肝癌细胞膜表面高表达的跨膜糖蛋白,能够调节肝癌细胞生长、诱导基质金属蛋白酶（matrix metalloprotei-nase,MMP）分泌、促进肝癌细胞侵袭和转移,并且参与肝癌血管生长和耐药性形成。以CD147为靶点的单克隆抗体治疗肝癌具有显著疗效。本文就肝癌细胞CD147的分子特点、功能与机理以及针对CD147的靶向治疗等方面研究进展作较全面的综述。     

Syndecan-1/CD147 association is essential for cyclophilin B-induced activation of p44/42 mitogen-activated protein kinases and promotion of cell adhesion and chemotaxis

Many of the biological functions attributed to cell surface proteoglycans are dependent on the interaction with extracellular mediators through their heparan sulphate (HS) moieties and the participation of their core proteins in signaling events. A class of recently identified inflammatory mediators is secreted cyclophilins, which are mostly known as cyclosporin A-binding proteins. We previously demonstrated that cyclophilin B (CyPB) triggers chemotaxis and integrin-mediated adhesion of T lymphocytes mainly of the CD4+/CD45RO+ phenotype. These activities are related to interactions with two types of binding sites, CD147 and cell surface HS. Here, we demonstrate that CyPB-mediated adhesion of CD4+/CD45RO+ T cells is related to p44/42 mitogen-activated protein kinase (MAPK) activation by a mechanism involving CD147 and HS proteoglycans (HSPG). Although HSPG core proteins are represented by syndecan-1, -2, -4, CD44v3 and betaglycan in CD4+/CD45RO+ T cells, we found that only syndecan-1 is physically associated with CD147. The intensity of the heterocomplex increased in response to CyPB, suggesting a transient enhancement and/or stabilization in the association of CD147 to syndecan-1. Pretreatment with anti-syndecan-1 antibodies or knockdown of syndecan-1 expression by RNA interference dramatically reduced CyPB-induced p44/p42 MAPK activation and consequent migration and adhesion, supporting the model in which syndecan-1 serves as a binding subunit to form the fully active receptor of CyPB. Altogether, our findings provide a novel example of a soluble mediator in which a member of the syndecan family plays a critical role in efficient interaction with signaling receptors and initiation of cellular responses.     

Golgi α1,2-mannosidase I induces clustering and compartmentalization of CD147 during epithelial cell migration

ABSTRACT

CD147 is a widely expressed matrix metalloproteinase inducer involved in the regulation of cell migration. The high glycosylation and ability to undergo oligomerization have been linked to CD147 function, yet there is limited understanding on the molecular mechanisms behind these processes. The current study demonstrates that the expression of Golgi α1,2-mannosidase I is key to maintaining the cell surface organization of CD147 during cell migration. Using an in vitro model of stratified human corneal epithelial wound healing, we show that CD147 is clustered within lateral plasma membranes at the leading edge of adjacent migrating cells. This localization correlates with a surge in matrix metalloproteinase activity and an increase in the expression of α1,2-mannosidase subtype IC (MAN1C1). Global inhibition of α1,2-mannosidase I activity with deoxymannojirimycin markedly attenuates the glycosylation of CD147 and disrupts its surface distribution at the leading edge, concomitantly reducing the expression of matrix metalloproteinase-9. Likewise, treatment with deoxymannojirimycin or siRNA-mediated knockdown of MAN1C1 impairs the ability of the carbohydrate-binding protein galectin-3 to stimulate CD147 clustering in unwounded cells. We conclude that the mannose-trimming activity of α1,2-mannosidase I coordinates the clustering and compartmentalization of CD147 that follows an epithelial injury.     

CD147与MMPs、VEGF在肿瘤发生发展中相互作用的研究进展

细胞外基质金属蛋白酶诱导因子（CD147）是一种高度糖基化的跨膜蛋白,属于免疫蛋白超家族成员。CD147为多功能型蛋白,可以参与人体的多种病理生理机制,其通过调节血管内皮生长因子（VEGF）和基质金属蛋白酶（MMPs）的表达参与恶性肿瘤的新生血管的生成及多重耐药性的产生。近年来随着对CD147在肿瘤发生发展中的研究不断深入,越来越多的发现使得CD147在肿瘤进展中的作用日益凸显。已经明确了其对肿瘤的进展及治疗的作用,在多种肿瘤中高表达,并随着肿瘤的恶性程度增高而增加,可以作为某些恶性肿瘤治疗的靶点。然而,CD147其他的功能包括充当T细胞的活化剂、神经识别分子和受体伴侣亲环素A的生理和病理机制还未明确。因此,有必要探索CD147在肿瘤中的特定功能,并阐明其产生机制是至关重要的。在此研究的基础上,现就CD147与MMPs、VEGF之间相互作用对肿瘤的转移和浸润的影响作一综述。     

CD147 regulates vascular endothelial growth factor-A expression, tumorigenicity, and chemosensitivity to curcumin in hepatocellular carcinoma

CD147, also named as extracelluar matrix metalloproteinase inducer (EMMPRIN), has been proved to be involved in several aspects of tumor progression. In addition to its ability to induce vascular endothelial growth factor (VEGF) production, it confers resistance to some chemotherapeutic drugs. To investigate the possible role of CD147 in the mouse hepatocarcinoma cell line Hepa1-6 with no metastatic potential in the lymph nodes, we used RNA interference (RNAi) approach to silence CD147 expression. The results showed that silencing of CD147 in Hepa1-6 cells significantly impeded the expression of VEGF-A at both mRNA and protein levels. The siRNA-treated cells exhibited significantly decreased growth ability when compared with control cells. Colony formation of CD147 deficient cells was dramatically inhibited in soft agar, and tumorigenicity was reduced in nude mice. Furthermore, the downregulation of CD147 expression also sensitized cells to be more sensitive to curcumin. These results suggested that CD147 might be a potential target for therapeutic antitumor drugs.     

CD147 与MMPs、VEGF在肿瘤发生发展中相互作用的研究进展

细胞外基质金属蛋白酶诱导因子(CD147)是一种高度糖基化的跨膜蛋白,属于免疫蛋白超家族成员。CD147 为多功能型蛋 白，可以参与人体的多种病理生理机制，其通过调节血管内皮生长因子（VEGF）和基质金属蛋白酶（MMPs）的表达参与恶性肿瘤的新生血管的生成及多重耐药性的产生。近年来随着对CD147 在肿瘤发生发展中的研究不断深入，越来越多的发现使得CD147在肿瘤进展中的作用日益凸显。已经明确了其对肿瘤的进展及治疗的作用，在多种肿瘤中高表达，并随着肿瘤的恶性程度增高而 增加，可以作为某些恶性肿瘤治疗的靶点。然而，CD147 其他的功能包括充当T 细胞的活化剂、神经识别分子和受体伴侣亲环素A的生理和病理机制还未明确。因此，有必要探索CD147 在肿瘤中的特定功能，并阐明其产生机制是至关重要的。在此研究的基础上，现就CD147 与MMPs、VEGF之间相互作用对肿瘤的转移和浸润的影响作一综述。