A calreticulin-like molecule from the human hookworm Necator americanus interacts with C1q and the cytoplasmic signalling domains of some integrins

Grit Kasper, Alan Brown, Matthias Eberl, Laurent Vallar, Nelly Kieffer, Colin Berry, Karen Girdwood, Paul Eggleton, Rupert Quinnell, David I. Pritchard*

*Corresponding author for this work

    Research output: Contribution to journalArticleResearchpeer-review

    93 Citations (Scopus)

    Abstract

    Calreticulin was recently identified as a hookworm (Necator americanus) allergen, implying secretion, and contact with cells of the immune system, or significant worm attrition in the tissues of the host. As human calreticulin has been shown to bind to and neutralize the haemolytic activity of the complement component C1q, and to be putatively involved in integrin-mediated intracellular signalling events in platelets, it was of interest to determine whether a calreticulin from a successful nematode parasite of humans, with known immune modulatory and antihaemostatic properties, exhibited a capacity to interfere with complement activation and to interact with integrin domains associated with cell signalling in platelets and other leucocytes. We can now report that recombinant calreticulin failed to demonstrate significant calcium binding capacity, which is a hallmark of calreticulins in general and may indicate inappropriate folding following expression in a prokaryote. Nevertheless, recombinant calreticulin retained sufficient molecular architecture to bind to, and inhibit the haemolytic capacity of, human C1q. Furthermore, recombinant calreticulin reacted in surface plasmon resonance analysis (SPR) with peptides corresponding to cytoplasmic signalling domains of the integrins αIIb and α5, in a calcium independent manner. SPR was also used to ratify the specificity of a polyclonal antibody to hookworm calreticulin, which was then used to assess the stage specificity of expression of the native molecule (in comparison with reverse transcriptase-polymerase chain reaction), to indicate its apparent secretion, and to purify native calreticulin from worm extracts by affinity chromatography. This development will allow the functional tests described above to be repeated for native calreticulin, to ascertain its role in the host-parasite relationship.

    Original languageEnglish
    Pages (from-to)141-152
    Number of pages12
    JournalParasite Immunology
    Volume23
    Issue number3
    DOIs
    Publication statusPublished - 2001

    Keywords

    • C1q
    • Calreticulin
    • Complement
    • Haemolysis
    • Hookworm
    • Necator americanus

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