Plasmatocyte spreading peptide does not induceMicroplitis demolitor polydnavirus-infected plasmatocytes to spread on foreign surfaces

Strand, Michael R.; Clark, Kevin C.; Gardiner, Elisabeth

doi:10.1002/(sici)1520-6327(1999)40:1<41::aid-arch5>3.0.co;2-r

Cited by 13 publications

(8 citation statements)

References 39 publications

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“…Although the protein precursor of the ENF peptide is activated in a manner analogous to those with most of the neuroactive and other biogenic peptides (37), the latter events following activation of the cytokine precursor have been poorly understood in insects as well as mammals. In the last instar larvae of Lepidoptera, the proportion of immune potent cells such as plasmatocytes and granular cells is extremely high: the two cell types comprise greater than 90% of the total circulating hemocyte population in Pseudoplusia includens (13,38). If the hemolymph concentration of the ENF peptide continuously keeps high enough to activate these immune cells, the larvae would possibly suffer serious damages through unnecessary excessive stimulation of these cells.…”

Section: Discussionsupporting

confidence: 78%

Insect Cytokine Growth-blocking Peptide Triggers a Termination System of Cellular Immunity by Inducing Its Binding Protein

Matsumoto

Oda

Uryu

et al. 2003

Journal of Biological Chemistry

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Growth-blocking peptide (GBP) is a 25-amino acid cytokine found in lepidopteran insects that possesses diverse biological activities such as stimulation of immune cells (plasmatocytes), cell proliferation, and larval growth regulation. We found another novel function of GBP that induces a hemolysis of another class of blood cells (oenocytoids). In the lysate of oenocytoids we identified a GBP-binding protein that shows a specific affinity for GBP. The characterization of purified GBP-binding protein and its cDNA demonstrated it as a 49.5-kDa novel protein with a C-terminal region displaying limited homology to several insect lipoproteins. Results of Northern and Western blotting indicated that the GBPbinding protein should be synthesized only in blood cells. Immunoelectron microscopic analyses confirmed that indirect immunoreactive signals were mostly localized in oenocytoids. Kinetic and biological analyses of interaction between GBP and the binding protein showed their strong binding was followed by clearance of GBP from hemolymph, thus indicating that this protein might function as an inhibitory factor against GBP. Based on these results, we propose that insect cytokine GBP shows multifunctions even in cellular immunity: it serves to stimulate immune cells and afterward silences its own action by inducing the binding protein through specific hemolysis.

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Section: Discussionsupporting

confidence: 78%

Insect Cytokine Growth-blocking Peptide Triggers a Termination System of Cellular Immunity by Inducing Its Binding Protein

Matsumoto

Oda

Uryu

et al. 2003

Journal of Biological Chemistry

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“…Clark et al (1997) reported that PSP1 dosedependently induces plasmatocytes to spread on planer surfaces in vitro and to aggregate in vivo. Plasmatocytes responding to PSP1 are labeled by the mAb marker 43E9A10, whereas plasmatocytes that remain unspread in the presence of PSP1 are labeled by other anti-plasmatocyte mAbs (Clark et al, 1997;Gardiner and Strand, 1999;Strand et al, 1999). These results indicated that plasmatocytes consist of at least two subpopulations and that PSP1 affects the adhesive state of plasmatocytes recognized by mAb 43-E9A10.…”

Section: Psp1 Induces Plasmatocytes From Other Lepidoptera To Aggregatementioning

confidence: 93%

“…As noted in the preceding experiments, plasmatocytes readily spread on foreign surfaces like culture plates. In contrast, plasmatocytes and granulocytes do not attach or spread on cultures plates precoated with the basement membrane product Matrigel or agarose Pech and Strand, 1996;Strand et al, 1999). Addition of PSP1 to plasmatocytes in agarose-coated wells induced cells to rapidly aggregate.…”

Section: Psp1 Induces Plasmatocytes To Aggregate When Cultured In Agamentioning

confidence: 99%

Plasmatocyte spreading peptide induces spreading of plasmatocytes but represses spreading of granulocytes

Strand

Clark

1999

Arch. Insect Biochem. Physiol.

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In most Lepidoptera, plasmatocytes and granulocytes are the two hemocyte classes capable of adhering to foreign targets. Previously, we identified plasmatocyte spreading peptide (PSP1) from the moth Pseudoplusia includens and reported that it induced plasmatocytes to rapidly spread on foreign surfaces. Here we examine whether the response of plasmatocytes to PSP1 was influenced by cell density or culture conditions, and whether PSP1 affected the adhesive state of granulocytes. Plasmatocyte spreading rates were clearly affected by cell density in the absence of PSP1 but spreading was density independent in the presence of PSP1. PSP1 also induced plasmatocytes in agarose‐coated culture wells to form homotypic aggregations rather than spread on the surface of culture wells. In contrast, granulocytes rapidly spread in a density independent manner in the absence of PSP1, but were dose‐dependently inhibited from spreading by the addition of peptide. An anti‐PSP1 polyclonal antibody neutralized the spreading activity of synthetic PSP1. This antibody also neutralized the plasmatocyte spreading activity of granulocyte‐conditioned medium, and significantly delayed plasmatocyte spreading when cells were cultured at a high density in unconditioned medium. These results suggested that the spreading activity derived from granulocytes is due in part to PSP1. Pretreatment of plasmatocytes with trypsin had no effect on PSP1‐induced aggregation but PSP1‐induced aggregations were readily dissociated by trypsin. This suggested that PSP1 is not an adhesion factor but induces adhesion by stimulating a change in the cell surface of plasmatocytes. Synthetic PSP1 also induced aggregation of plasmatocytes from other Lepidoptera indicating that regulation of hemocyte activity by PSP1‐related peptides may be widespread. Arch. Insect Biochem. Physiol. 42:213–223, 1999. © 1999 Wiley‐Liss, Inc.

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“…Studies with several parasitoid-host systems have indicated that PDV-infected hosts do not mount an encapsulation response, which in turn allows the parasitoid's offspring to successfully develop (1,7,11,19,28,31,44). Hosts parasitized by the braconid Microplitis demolitor are unable to encapsulate parasitoid eggs or other foreign targets because hemocytes infected by M. demolitor bracovirus (MdBV) lose the capacity to adhere to foreign surfaces by 4 to 6 h postinfection (31,33). Hemocytes in primary culture and the hemocyte-like cell line BTI-TN-5B1-4 (High Five) from Trichoplusia ni also lose the ability to adhere to foreign surfaces after infection by MdBV (3,31).…”

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confidence: 97%

Glc1.8 fromMicroplitis demolitorBracovirus Induces a Loss of Adhesion and Phagocytosis in Insect High Five and S2 Cells

Beck

Strand

2005

J Virol

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Polydnaviridae is a unique family of DNA viruses that are symbiotically associated with parasitoid wasps. Upon oviposition, wasps inject these viruses into their hosts, where they cause several physiological alterations, including suppression of the cellular immune response. Here we report that expression of the glc1.8 gene from Microplitis demolitor bracovirus (MdBV) causes a loss of adhesion by two hemocyte-like cell lines, namely, High Five cells from the lepidopteran Trichoplusia ni and S2 cells from the dipteran Drosophila melanogaster. The expression of recombinant Glc1.8 also greatly reduced the ability of these cells to phagocytize foreign targets. Glc1.8 is characterized by a signal peptide at its N terminus, an extracellular domain comprised of five nearly perfect tandem repeats of 78 amino acids, and a C-terminal hydrophobic domain that encodes a putative membrane anchor sequence. The expression of a Glc1.8 mutant lacking the anchor sequence resulted in a secreted protein that had no effect on adhesion or phagocytosis. In contrast, sequential deletion of the repeats in the extracellular domain resulted in a progressive reduction in immunosuppressive activity. Since each repeat and its associated glycosylation sites are nearly identical, these results suggested that adhesion-blocking activity depends more on the overall number of repeats in the extracellular domain than on the specific determinants within each repeat. While it severely compromised adhesion and phagocytic functions, Glc1.8 did not cause cell death. Collectively, these results indicate that Glc1.8 is a major pathogenic determinant of MdBV that is involved in suppression of the insect cellular immune response.

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Plasmatocyte spreading peptide does not induceMicroplitis demolitor polydnavirus-infected plasmatocytes to spread on foreign surfaces

Cited by 13 publications

References 39 publications

Insect Cytokine Growth-blocking Peptide Triggers a Termination System of Cellular Immunity by Inducing Its Binding Protein

Insect Cytokine Growth-blocking Peptide Triggers a Termination System of Cellular Immunity by Inducing Its Binding Protein

Plasmatocyte spreading peptide induces spreading of plasmatocytes but represses spreading of granulocytes

Glc1.8 fromMicroplitis demolitorBracovirus Induces a Loss of Adhesion and Phagocytosis in Insect High Five and S2 Cells

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