Cholesterol depletion associated with Leishmania major infection alters macrophage CD40 signalosome composition and effector function

Rub, Abdur; Dey, Ranadhir; Jadhav, Meenakshi; Kamat, Rohan; Chakkaramakkil, Santhosh; Majumdar, Subrata; Mukhopadhyaya, Robin; Saha, Bhaskar

doi:10.1038/ni.1705

Cited by 109 publications

(159 citation statements)

References 55 publications

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Section: Discussionsupporting

confidence: 91%

“…Thus, we concluded that the ERK and p38 signaling pathways are independent of each other. Recent study supports strongly our results by showing the critical role of lipid rafts integrity in p38 and ERK1/2 phosphorylation [44].Previous data indicated that PKC mediate downstream signal following activation through MAP kinase and transcriptional factors. However, this activation of the PKC is involved only in the downstream signaling implicating p38 but not ERK1/2 since their inhibition by the total inhibitor chelerythrine did not affect the phosphorylation of the ERK1/2 kinase.…”

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confidence: 91%

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Critical role of lipid rafts in CD154‐mediated T cell signaling

et al. 2010

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Although signal pathways triggered via the CD40 molecule are well characterized, those induced via CD154 are less known. This study demonstrates that engagement of CD154 in Jurkat D1.1 cells with soluble CD40 leads to PKC a and d activation, calcium mobilization, and phosphorylation of the Map kinases ERK1/2 and p38. Such response is accompanied by significant recruitment of CD154 into lipid rafts. Disruption of lipid rafts integrity with nystatin or methyl b-cyclodextrin abrogated PKCa PKCd and p38 phosphorylation, but had no effect on ERK1/2 phosphorylation. Inhibition of PKC activation completely abolished p38 phosphorylation but had no effect on ERK1/2 phosphorylation, suggesting that localization of CD154 within lipid rafts is an absolute requirement for CD154-induced PKCaand PKCd-dependent p38 phosphorylation. Furthermore, CD154 acts as co-stimulator for the production of IL-2 in an APC-superantigen-T-cell activation model. The results obtained demonstrate for the first time, that lipid rafts are of immunological relevance for CD154-triggered signals, and reinforce the importance of CD154 in T-cell activation.Key words: CD154 . Lipid rafts . Signaling . T lymphocytes Introduction CD154 is a type II transmembrane protein, member of the TNF superfamily, originally detected on the surface of stimulated CD4 1 T cells. Since then, CD154 was found on the surface of activated CD8 1 T cells, gd T cells, B cells, basophils, mast cells, macrophages, dendritic cells, activated platelets, and nonhematopoietic cells such as endothelial cells and fibroblasts [1][2][3][4][5][6][7]. In addition to its transmembrane form, CD154 is also released as a soluble protein by cleavage of the extracellular domain [8,9]. CD154 acts as a ligand for its classical receptor CD40 that is expressed on various cell types of hematopoietic and nonhematopoietic origin such as B cells, macrophages, dendritic cells, platelets, and endothelial and epithelial cells [5]. Recently, three other functional receptors for CD154 have been described, namely the integrins aIIbb3 [6], a5b1 [10], and Mac-1 [11].CD154 is a crucial costimulatory molecule for the development of both humoral and cellular immune responses [5], and plays an important role in the development and/or maintenance of autoimmune and inflammatory diseases [12][13][14][15]. The absence of CD154 leads to hyper-IgM syndrome, abrogation of germinal center formation and failure of B cells to proliferate and differentiate [5,16].The downstream signals triggered via CD40 molecule are extensively studied [5]. However, the signaling pathways linked to CD154 remain poorly known. Previous studies indicate that CD154 accumulate at T cell-APC contact sites in the immunological synapse [17], and that ligation of CD154 on T cells with specific Ab triggers the activation of src kinases, PKC, and MAP kinases [18][19][20], leading to cytokines secretion [21,22] 770CD3-induced T-cell proliferation [23] and apoptosis [22]. However, the precise mechanism by which CD154-triggered signaling is accomplished r...

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Section: Discussionsupporting

confidence: 91%

supporting

confidence: 91%

Critical role of lipid rafts in CD154‐mediated T cell signaling

et al. 2010

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“…CD40 (i.p., 50 mg/mouse; clone 3/23) for 3 d alternatively beginning day 4 postinfection. Disease severity was assessed by measurement of footpad swelling using a digital micrometer (Mitutuyo Japan) and parasite burden (11,12).…”

Section: Mice Parasites and Infectionmentioning

confidence: 99%

“…CD40 is a costimulatory receptor expressed by macrophages, B cells, dendritic cells, and endothelial cells and is the only receptor for which reciprocal signaling has been worked out (10)(11)(12). CD40 stimulation by anti-CD40 Ab results in differential and reciprocal regulation of p38MAPK, ERK1/2 phosphorylation, and IL-10 and IL-12 production (11).…”

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confidence: 99%

Reciprocal Regulation of Protein Kinase C Isoforms Results in Differential Cellular Responsiveness

Sudan

Srivastava

Pandey

et al. 2012

The Journal of Immunology

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Immunological homeostasis is often maintained by counteractive functions of two different cell types or two different receptors signaling through different intermediates in the same cell. One of these signaling intermediates is protein kinase C (PKC). Ten differentially regulated PKC isoforms are integral to receptor-triggered responses in different cells. So far, eight PKC isoforms are reported to be expressed in macrophages. Whether a single receptor differentially uses PKC isoforms to regulate counteractive effector functions has never been addressed. As CD40 is the only receptor characterized to trigger counteractive functions, we examined the relative role of PKC isoforms in the CD40-induced macrophage functions. We report that in BALB/c mouse macrophages, higher doses of CD40 stimulation induce optimum phosphorylation and translocation of PKCα, βI, βII, and ε whereas lower doses of CD40 stimulation activates PKCδ, ζ, and λ. Infection of macrophages with the protozoan parasite Leishmania major impairs PKCα, βI, βII, and ε isoforms but enhances PKCδ, ζ, and λ isoforms, suggesting a reciprocity among these PKC isoforms. Indeed, PKCα, βI, βII, and ε isoforms mediate CD40-induced p38MAPK phosphorylation, IL-12 expression, and Leishmania killing; PKCδ and ζ/λ mediate ERK1/2 phosphorylation, IL-10 production, and parasite growth. Treatment of the susceptible BALB/c mice with the lentivirally expressed PKCδ- or ζ-specific short hairpin RNA significantly reduces the infection and reinstates host-protective IFN-γ–dominated T cell response, defining the differential roles for PKC isoforms in immune homeostasis and novel PKC-targeted immunotherapeutic and parasite-derived immune evasion strategies.

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“…Sustained localization of CD40 to lipid rafts has been implicated in the enhanced proliferation of B cells in non-Hodgkin's lymphomas [23]. The manipulation of membrane cholesterol by Leishmania major alters CD40 lipid raft localization and subsequent signaling events, skewing the response from Th1 to Th2 and increasing the susceptibility of macrophages to infection [24]. In addition, CD40 is upregulated and constitutively associates with lipid rafts in an auto-aggressive subset of T cells in a murine model of diabetes [25].…”

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confidence: 99%

CD40 translocation to lipid rafts: Signaling requirements and downstream biological events

et al. 2011

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CanadaCD40, a member of the TNF receptor family, is expressed on a variety of immune and nonimmune cells. Its interaction with its ligand, CD154, plays a pivotal role in humoral and cellmediated immunity. A low level of CD40 is constitutively associated within membrane lipid rafts and, upon engagement, this level is significantly enhanced. In this study, our objective is to evaluate the process of CD40/lipid raft association in terms of the signals required for its initiation and the resulting biological outcomes. Here, we show the CD40/lipid raft association to be independent of PI-3-kinase, Src family kinases and p38 MAPK pathways. Moreover, CD40 lacking its intracellular domain, which is usually required for CD40-mediated signaling, still localizes to lipid rafts upon engagement, confirming that the CD40/ lipid raft association is independent of signaling events. As to the biological outcomes of the CD40/lipid raft association, we show that disrupting lipid raft integrity selectively abolishes CD40-mediated Akt phosphorylation. In addition, replacing the transmembrane domain of CD40 with that of CD45 (a protein excluded from lipid rafts) dramatically reduced CD40-mediated Akt phosphorylation and B7.1 upregulation, while not influencing p38, ERK and JNK activation. Together, these findings clarify the requirements for CD40/lipid raft association and the signals triggered upon CD40 engagement by CD154.Keywords: CD40 . Lipid rafts . Signaling . Transmembrane domain Supporting Information available online IntroductionInteraction between the TNFR, CD40 and its ligand CD154 drives crucial steps in humoral immune responses [1][2][3]. Notably, the CD40/CD154 interaction is critical for the affinity maturation of immunoglobulins (Ig), the development of long-lived plasma B cells and the clonal expansion of memory B cells [1,4,5]. In the absence of intrinsic tyrosine kinase activity, CD40 transmits its intracellular signal via recruitment of several adaptor proteins, such as JAK3 [6] and TNFR-associated factor (TRAF) proteins [5], to specific domains in the CD40 cytoplasmic tail [4,[7][8][9]. This results in the activation of members of the Src kinase family (such as Lyn and Fyn), and other protein tyrosine kinases (such as Syk and Btk) [10,11]; the activation of PI-3 kinase and phospholipase Cg2 [11] and the activation of the MAP kinases p38, JNK and ERK [12][13][14].Lipid rafts are detergent-resistant plasma membrane microdomains that are enriched in cholesterol and sphingolipids. Being 2358scaffolds of many signaling effectors including lipid-anchored proteins (such as Thy-1 and alkaline phosphatase) and signaling molecules (such as some Src kinase family members), lipid rafts act as platforms to initiate and regulate signal transduction processes in many cellular models [15,16]. Engagement of CD40 molecules leads to CD40 clustering into ceramide-enriched lipid rafts of living human B cells [17,18]. Common early events following CD40 clustering in mouse B cells [19] and in human dendritic cells [20] include Lyn act...

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Cholesterol depletion associated with Leishmania major infection alters macrophage CD40 signalosome composition and effector function

Cited by 109 publications

References 55 publications

Critical role of lipid rafts in CD154‐mediated T cell signaling

Critical role of lipid rafts in CD154‐mediated T cell signaling

Reciprocal Regulation of Protein Kinase C Isoforms Results in Differential Cellular Responsiveness

CD40 translocation to lipid rafts: Signaling requirements and downstream biological events

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