PKCδ and cofilin activation affects peripheral actin reorganization and cell-cell contact in cells expressing integrin α5 but not its tailless mutant

Oh, Min-A; Kang, Eun‐Sil; Lee, Sin-Ae; Lee, Eun-Ok; Kim, Yong-Bae; Kim, Sung Hoon; Lee, Sang Eun

doi:10.1242/jcs.003566

Cited by 19 publications

(18 citation statements)

References 52 publications

(70 reference statements)

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“…Furthermore, we show that each step of ␤ 1 integrin-mediated signaling leading to the activation of the downstream targets (20) is crucial for EBV entry into B cells. Very importantly, activation of memory B cells from peripheral blood with CD40L plus anti-IgM resulted in a vigorous upregulation of ␤ 1 integrin expression.…”

Section: Discussionmentioning

confidence: 84%

β₁Integrin Expression Increases Susceptibility of Memory B Cells to Epstein-Barr Virus Infection

Dorner

Zucol

Alessi

et al. 2010

J Virol

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Epstein-Barr virus (EBV) uses nasal mucosa-associated lymphoid tissue (NALT) as a portal of entry toEpstein-Barr virus (EBV) is a ubiquitous human gammaherpesvirus that is transmitted via saliva and infects more than 90% of the world's population (21). Much of EBV's medical importance relates to its association with B-cell malignancies, including Burkitt's lymphoma, Hodgkin's lymphoma, and posttransplant lymphoproliferative disease (21). The oncogenic potential of EBV is clearly illustrated by its unique capability to transform B cells in vitro (21).In the current paradigm, EBV infects naïve B cells in tonsils in vivo (32). EBV is present mainly as a latent virus; upon infection, EBV expresses distinct patterns of its latency genes depending upon distinct B-cell differentiation stages, varying from expression of all 10 known EBV latency genes in naïve B cells to the complete absence of EBV mRNA expression in resting memory B cells. This has led to the model that EBV, by virtue of expression of its latency genes, provides cell survival signals in naïve B cells (32). In particular, recent data suggest that EBV expedites the antigen-driven somatic hypermutation and selection of B cells taking place in germinal centers (GC) (26). Chaganti et al. challenged the current paradigm by showing for patients with primary EBV infection that EBV avoids GC transit and directly infects memory B cells (6). This report is consistent with in vitro experiments showing that EBV is able to infect memory B cells (9, 10), in addition to the well-accepted susceptibility of naïve and GC B cells to EBV.Irrespective of which B-cell subset is the primary target of EBV, its propagation within the host is linked to proliferation of infected B cells, which deliver latent EBV to daughter cells, or, more rarely, to switching of EBV to lytic infection (21). The latter process can eventually be triggered by the differentiation of infected memory B cells into plasma cells and results in the release of virions that may subsequently infect new B cells (17). Importantly, transmission of EBV to naïve hosts is thought to occur via droplets loaded with virions (21). Thus, lytic replication of EBV takes place best in nasal mucosa-associated lymphoid tissue (NALT), which will release EBV into the saliva, generating infectious droplets. Therefore, the NALT is the point of EBV transmission, i.e., the portal of entry of EBV as well as a shedding organ for further transmission (21).The attachment of EBV to B cells is mediated by the direct interaction of EBV glycoprotein gp350/220 with cellular CD21, initiating receptor-mediated endocytosis. After binding to CD21, EBV gp42 can interact with host HLA class II molecules, leading to a conformational change in the viral glycoproteins and triggering fusion with the host cell membrane (12,28). Nevertheless, experimental data suggest that CD21 and HLA class II molecules are dispensable for the infection of B cells (14). Notably, in polarized oropharyngeal epithelial cells, which lack CD21, interactions between ␤1 int...

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Section: Discussionmentioning

confidence: 84%

β₁Integrin Expression Increases Susceptibility of Memory B Cells to Epstein-Barr Virus Infection

Dorner

Zucol

Alessi

et al. 2010

J Virol

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“…PKC-␦ isoform differentially regulates secretion in many cells. 9,14,34 This isoform positively regulates PAR-mediated dense granule secretion, whereas it negatively regulates GPVI-mediated dense granule secretion. In the current study, we investigated the mechanism of such differential regulation of platelet-dense granule secretion by PKC-␦.…”

Section: Discussionmentioning

confidence: 99%

Lyn, PKC-δ, SHIP-1 interactions regulate GPVI-mediated platelet-dense granule secretion

Chari

Kim

Murugappan

et al. 2009

Blood

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Protein kinase C-␦ (PKC-␦) is expressed in platelets and activated downstream of protease-activated receptors (PARs) and glycoprotein VI (GPVI) receptors. We have previously shown that PKC-␦ positively regulates PAR-mediated dense granule secretion, whereas it negatively regulates GPVI-mediated dense granule secretion. We further investigated the mechanism of such differential regulation of dense granule release by PKC-␦ in platelets. SH2 domain-containing inositol phosphatase-1 (SHIP-1) is phosphorylated on Y1020, a marker for its activation, upon stimulation of human platelets with PAR agonists SFLLRN and AYPGKF or GPVI agonist convulxin. GPVI-mediated SHIP-1 phosphorylation occurred rapidly at 15 seconds, whereas PAR-mediated phosphorylation was delayed, occurring at 1 minute. Lyn and SHIP-1, but not SHIP-2 or Shc, preferentially associated with PKC-␦ on stimulation of platelets with a GPVI agonist, but not with a PAR agonist. In PKC-␦-null murine platelets, convulxin-induced SHIP-1 phosphorylation was inhibited. IntroductionPlatelet-collagen interactions are thought to have the greatest significance at medium or high shear rates found in arteries and diseased vessels. 1 Glycoprotein VI (GPVI) is the major signaling receptor for collagen on the platelet surface. 1 The critical role played by platelets in hemostasis, thrombosis and vascular remodeling, and healing is related to their function as exocytotic cells that secrete important effector molecules at the site of vascular injury. Platelets normally contain at least 3 types of large intracellular granules, such as ␣, dense, and lysosomal granules. There are 3 to 8 dense granules per platelet, and the contents from these dense granules are important for recruiting more platelets to the site of injury. 2,3 Protein kinase C (PKC) has been implicated in platelet secretion. 4 Protein kinase Cs are members of the extended AGC (protein kinases A, G, and C) family of differentially expressed serine/ threonine kinases implicated in a diverse array of cellular functions. After activation, these kinases migrate to different subcellular locations, including the plasma membrane and cytoskeletal elements where they regulate different physiologic functions. 5 PKC isoforms are subdivided into 3 groups based on their lipid and cofactor requirements: the diacylglycerol and calcium-sensitive conventional isoforms (␣, ␤I, ␤II and ␥), the diacylglycerolsensitive and calcium-insensitive novel isoforms (␦, , , and ⑀), and the phosphatidylinositide trisphosphate-sensitive atypical isoforms (, , , and ). 6 PKC-␦ plays a key role in growth regulation and tissue remodeling in other cells 7 and differentially regulates dense granule secretion in platelets. It positively regulates proteaseactivated receptor (PAR)-mediated dense granule release and negatively regulates GPVI-mediated dense granule release. [8][9][10] Intrinsic function of PKCs is regulated by 3 mechanisms: (1) binding of the cofactor that allosterically activates the enzyme, (2) phosphorylation on the activation loop r...

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“…In this report, we demonstrate that a fraction of PKCδ localizes to cellcell junctions, where it exerts a suppressive effect on the function of E-cadherin. Accordingly, it has recently been reported that activation of PKCδ is involved in the regulation of peripheral actin organization and cell-cell contacts in the epithelium (Oh et al, 2007). In addition, PKCδ has been implicated as modulating tight junctions (Mullin et al, 1998;Eckert et al, 2005).…”

Section: Discussionmentioning

confidence: 99%

Functional suppression of E-cadherin by protein kinase Cδ

Chen

2009

Journal of Cell Science

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Journal of Cell Science 514 cell functions, including cell proliferation (Ashton et al., 1999;Kitamura et al., 2003), differentiation (Corbit et al., 1999;Pessino et al., 1995), apoptosis (Brodie and Blumberg, 2003;Kajimoto et al., 2004;Zhong et al., 2002) and tumor suppression (Lu et al., 1997;Reddig et al., 1999). Increasing evidence also indicates that PKCδ has a positive role in cell motility (Chen et al., 2007;Gliki et al., 2002;Iwabu et al., 2004;Li et al., 2003) and the metastatic potential of tumor cells (Kiley et al., 1999;Kruger and Reddy, 2003; Alonso-Escolano et al., 2006;Kharait et al., 2006;Villar et al., 2007). However, the role of PKCδ in intercellular junctions remains obscure. In this study, we aim to explore the role of PKCδ in cellcell junctions using Madin-Darby canine kidney (MDCK) cells as a model. Results Expression of GFP-PKCδ, but not GFP-PKCα, suppresses the homophilic interactions between the ectodomains of E-cadherins in MDCK cellsTo explore the role of PKC in cell-cell junctions, GFP-PKCδ and GFP-PKCα were stably expressed in MDCK cells (Fig. 1A). Expression of either construct in those cells did not alter their growth (data not shown) or their ability to form cell colonies within which the cells are in contact with each other (Fig. 1B). To examine their effect on adherens junctions and tight junctions, cells stably expressing GFP-PKCδ or GFP-PKCα were co-cultured with parental control MDCK cells and then grown to confluence. The cells were fixed and stained for adherens junctions and tight junctions with anti-E-cadherin and anti-ZO-1, respectively. Neither GFP-PKCδ nor GFP-PKCα affected tight junctions of MDCK cells (Fig. 1C,D). However, the fluorescence intensity of E-cadherin at cell-cell contacts in the cells expressing GFP-PKCδ, but not GFP-PKCα, was much weaker than that in adjacent parental MDCK cells (Fig. 1C,D).As the total and cell surface levels of E-cadherins were not altered by GFP-PKCδ (supplementary material Fig. S1), it is unlikely that the decreased fluorescence intensity of E-cadherin was due to suppression of E-cadherin expression. The rat monoclonal anti-Ecadherin (clone ECCD-2) used in Fig. 1C is known to recognize the extracellular domain of E-cadherin, rendering it possible that GFP-PKCδ causes a conformational change on the ectodomain of E-cadherin, which then prevents E-cadherins from detection by the ECCD-2 antibody. To clarify this, a mouse monoclonal antibody (clone 36) that recognizes the cytoplasmic portion of E-cadherins was used. The fluorescence intensity of E-cadherin with the clone 36 antibody did not show differences between control cells and PKCδ-overexpressed cells ( Fig. 2A), supporting the idea that the conformation of E-cadherins rather than their distribution or expression is affected by PKCδ. In addition, we found that the ability of the ECCD-2 antibody, but not the clone 36 antibody, to detect E-cadherin at cell-cell junctions relied on the presence of Ca 2+ in the culture medium, as demonstrated by Ca 2+ -switch assay (Fig. 2B), indicat...

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PKCδ and cofilin activation affects peripheral actin reorganization and cell-cell contact in cells expressing integrin α5 but not its tailless mutant

Abstract: SummaryPKC␦ and cofilin activation affects peripheral actin reorganization and cell-cell contact in cells expressing integrin ␣5 but not its tailless mutant

Cited by 19 publications

References 52 publications

β₁Integrin Expression Increases Susceptibility of Memory B Cells to Epstein-Barr Virus Infection

β₁Integrin Expression Increases Susceptibility of Memory B Cells to Epstein-Barr Virus Infection

Lyn, PKC-δ, SHIP-1 interactions regulate GPVI-mediated platelet-dense granule secretion

Functional suppression of E-cadherin by protein kinase Cδ

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PKCδ and cofilin activation affects peripheral actin reorganization and cell-cell contact in cells expressing integrin α5 but not its tailless mutant

Abstract: SummaryPKC␦ and cofilin activation affects peripheral actin reorganization and cell-cell contact in cells expressing integrin ␣5 but not its tailless mutant

Cited by 19 publications

References 52 publications

β1Integrin Expression Increases Susceptibility of Memory B Cells to Epstein-Barr Virus Infection

β1Integrin Expression Increases Susceptibility of Memory B Cells to Epstein-Barr Virus Infection

Lyn, PKC-δ, SHIP-1 interactions regulate GPVI-mediated platelet-dense granule secretion

Functional suppression of E-cadherin by protein kinase Cδ

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β₁Integrin Expression Increases Susceptibility of Memory B Cells to Epstein-Barr Virus Infection

β₁Integrin Expression Increases Susceptibility of Memory B Cells to Epstein-Barr Virus Infection