Neurite outgrowth inhibitory levels of organophosphates induce tissue transglutaminase activity in differentiating N2a cells:evidence for covalent adduct formation


Organophosphate compounds (OPs) induce both acute and delayed neurotoxic effects, the latter of which is believed to involve their interaction with proteins other than acetylcholinesterase. However, few OP-binding proteins have been identified that may have a direct role in OP-induced delayed neurotoxicity. Given their ability to disrupt Ca2+ homeostasis, a key aim of the current work was to investigate the effects of sub-lethal neurite outgrowth inhibitory levels of OPs on the Ca2+-dependent enzyme tissue transglutaminase (TG2). At 1–10 µM, the OPs phenyl saligenin phosphate (PSP) and chlorpyrifos oxon (CPO) had no effect cell viability but induced concentration-dependent decreases in neurite outgrowth in differentiating N2a neuroblastoma cells. The activity of TG2 increased in cell lysates of differentiating cells exposed for 24 h to PSP and chlorpyrifos oxon CPO (10 µM), as determined by biotin-cadaverine incorporation assays. Exposure to both OPs (3 and/or 10 µM) also enhanced in situ incorporation of the membrane permeable substrate biotin-X-cadaverine, as indicated by Western blot analysis of treated cell lysates probed with ExtrAvidin peroxidase and fluorescence microscopy of cell monolayers incubated with FITC-streptavidin. Both OPs (10 µM) stimulated the activity of human and mouse recombinant TG2 and covalent labelling of TG2 with dansylamine-labelled PSP was demonstrated by fluorescence imaging following SDS-PAGE. A number of TG2 substrates were tentatively identified by mass spectrometry, including cytoskeletal proteins, chaperones and proteins involved protein synthesis and gene regulation. We propose that the elevated TG2 activity observed is due to the formation of a novel covalent adduct between TG2 and OPs.

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Divisions: College of Health & Life Sciences > School of Biosciences
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Uncontrolled Keywords: Covalent adduct,Neurite outgrowth,Organophosphate toxicity,Tissue transglutaminase,Toxicology,Health, Toxicology and Mutagenesis
Publication ISSN: 1432-0738
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Related URLs: http://www.scop ... tnerID=8YFLogxK (Scopus URL)
https://link.sp ... 204-020-02852-w (Publisher URL)
PURE Output Type: Article
Published Date: 2020-11-01
Published Online Date: 2020-08-04
Accepted Date: 2020-07-14
Authors: Almami, Ibtesam S.
Aldubayan, Maha A.
Felemban, Shatha G.
Alyamani, Najiah
Howden, Richard
Robinson, Alexander J.
Pearson, Tom D.Z.
Boocock, David
Algarni, Alanood S.
Garner, A. Christopher
Griffin, Martin (ORCID Profile 0000-0003-3824-306X)
Bonner, Philip L.R.
Hargreaves, Alan J.



Version: Published Version

License: Creative Commons Attribution

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