Neurofilament 200 as an Indicator of Differences Between Mipafox and Paraoxon Sensitivity in SY5Y Neuroblastoma Cells

Abstract

Organophosphorus (OP) compounds produce potent neurotoxic effects in humans, including organophosphorus-induced delayed neuropathy (OPIDN). This investigation examined the potential for the 200-kD neurofilament protein (NF200) and other neuronal proteins to serve as indicators for neurite damage in a differentiated SY5Y human neuroblastoma cell culture system. Mipafox, which induces OPIDN, increased NF200 protein expression in SY5Y cells differentiated with human recombinant beta-nerve growth factor (NGF, 20 ng/ml) in a concentration-dependent manner, compared to NGF controls, when SY5Y cells were exposed to 0.3 or 30 microM mipafox during the last 5 days of neurite extension (experimental set A). However, mipafox produced little change in NF200 protein expression in SY5Y cells exposed continuously throughout neurite elongation (experimental set B). Paraoxon (up to 30 microM), which does not produce OPIDN, did not produce any change in NF200 expression in set A or set B. The upregulation of NF200 by mipafox may represent a compensatory response to neurite degeneration. Two other neuronal proteins, growth-associated protein 43 (GAP43) and microtubule-associated protein 2ab (MAP2ab), showed no changes in response to OP treatment in NGF-treated cells. Protein expression of NF200 was shown to be an indicator by which the sensitivities of SY5Y cells to mipafox and paraoxon were distinguishable at the molecular level. These results indicate an alternative approach and test system for investigating structure-activity relationships of OPs.

Identification of differentially expressed genes in SHSY5Y cells exposed to okadaic acid by suppression subtractive hybridization

“…NEF protein levels are correlative to neurite outgrowth, and its gene expression is dramatically altered in neurodegenerative diseases, including Parkinson's disease and Alzheimer's disease [60]. NEF protein levels have also been suggested as a potential biomarker in organophosphorous neurotoxicity [36]. Furthermore, neurite outgrowth can be promoted by nerve growth factor (NGF) via the regulation of NEF gene expression and NEF protein phosphorylation [61].…”

In vitro study of the neuropathic potential of the organophosphorus compounds trichlorfon and acephate

“…Mipafox and paraoxon are two well-studied OPs; the first has been described as inducer of OPIDN, and the second is known as an acutely toxic, but non-neuropathic OP (Ehrich et al, 1997). Studies in human and murine neuroblastoma cell lines have shown that paraoxon (non-neuropathic) inhibits AChE even at nanomolar concentrations, but only inhibits NTE at high concentrations; while mipafox (neuropathic) inhibits AChE weakly, but inhibits NTE at low concentrations (Ehrich et al, 1997;Cho and Tiffany-Castiglioni, 2004). The inhibition of AChE is enough for the generation of the cholinergic syndrome, but not for the development of OPIDN, which depends on the inhibition and aging of at least 70% of NTE (Ehrich et al, 1997).…”

Morphological and functional differentiation in BE(2)-M17 human neuroblastoma cells by treatment with Trans-retinoic acid

“…The use of different in vitro cell culture assays for predicting the in vivo effects of these chemicals have been extensively reviewed in recent years and the issues pertaining to their use have also been discussed [1-5]. The in vitro systems have been developed and utilized not only to understand the mechanisms of toxicity at the molecular and cellular levels but also to screen potential neurotoxicants.…”