Research

Plasmatocyte-spreading peptide (PSP) plays a central role in insect cellular immune defenses against bacterial infection


Reference:

Eleftherianos, I., Xu, M., Yadi, H., Ffrench-Constant, R. H. and Reynolds, S. E., 2009. Plasmatocyte-spreading peptide (PSP) plays a central role in insect cellular immune defenses against bacterial infection. The Journal of Experimental Biology, 212 (12), pp. 1840-1848.

Related documents:

This repository does not currently have the full-text of this item.
You may be able to access a copy if URLs are provided below. (Contact Author)

Official URL:

http://dx.doi.org/10.1242/jeb.026278

Abstract

Insect hemocytes (blood cells) are a central part of the insect's cellular response to bacterial pathogens, and these specialist cells can both recognize and engulf bacteria. During this process, hemocytes undergo poorly characterized changes in adhesiveness. Previously, a peptide termed plasmatocyte-spreading peptide (PSP), which induces the adhesion and spreading of plasmatocytes on foreign surfaces, has been identified in lepidopteran insects. Here, we investigate the function of this peptide in the moth Manduca sexta using RNA interference (RNAi) to prevent expression of the precursor protein proPSP. We show that infection with the insect-specific bacterial pathogen Photorhabdus luminescens and non-pathogenic Escherichia coli induces proPSP mRNA transcription in the insect fat body but not in hemocytes; subsequently, proPSP protein can be detected in cell-free hemolymph. We used RNAi to silence this upregulation of proPSP and found that the knock-down insects succumbed faster to infection with P. luminescens, but not E. coli. RNAi-treated insects infected with E. coli showed a reduction in the number of circulating hemocytes and higher bacterial growth in hemolymph as well as a reduction in overall cellular immune function compared with infected controls. Interestingly, RNAi-mediated depletion of proPSP adversely affected the formation of melanotic nodules but had no additional effect on other cellular responses when insects were infected with P. luminescens, indicating that this pathogen employs mechanisms that suppress key cellular immune functions in M. sexta. Our results provide evidence for the central role of PSP in M. sexta cellular defenses against bacterial infections.

Details

Item Type Articles
CreatorsEleftherianos, I., Xu, M., Yadi, H., Ffrench-Constant, R. H. and Reynolds, S. E.
DOI10.1242/jeb.026278
Uncontrolled Keywordscellular response, photorhabdus luminescens, manduca sexta, plasmatocyte-spreading peptide, rnai interference, insect immunity
DepartmentsFaculty of Science > Biology & Biochemistry
RefereedYes
StatusPublished
ID Code14434

Export

Actions (login required)

View Item