TY - JOUR
T1 - Chlorpyrifos, chlorpyrifos-oxon, and diisopropylfluorophosphate inhibit kinesin-dependent microtubule motility
AU - Gearhart, Debra A.
AU - Sickles, Dale W.
AU - Buccafusco, Jerry J.
AU - Prendergast, Mark A.
AU - Terry, Alvin V.
N1 - Funding Information:
The National Institutes of Health (NIH) provided funding for this work with research grants R01ES011223 (DWS) and R01ES012241 (AVT). The authors wish to thank Angie Testino for her technical assistance with these studies.
PY - 2007/1/1
Y1 - 2007/1/1
N2 - Diisopropylfluorophosphate, originally developed as a chemical warfare agent, is structurally similar to nerve agents, and chlorpyrifos has extensive worldwide use as an agricultural pesticide. While inhibition of cholinesterases underlies the acute toxicity of these organophosphates, we previously reported impaired axonal transport in the sciatic nerves from rats treated chronically with subthreshold doses of chlorpyrifos. Those data indicate that chlorpyrifos (and/or its active metabolite, chlorpyrifos-oxon) might directly affect the function of kinesin and/or microtubules-the principal proteins that mediate anterograde axonal transport. The current report describes in vitro assays to assess the concentration-dependent effects of chlorpyrifos (0-10 μM), chlorpyrifos-oxon (0-10 μM), and diisopropylfluorophosphate (0-0.59 nM) on kinesin-dependent microtubule motility. Preincubating bovine brain microtubules with the organophosphates did not alter kinesin-mediated microtubule motility. In contrast, preincubation of bovine brain kinesin with diisopropylfluorophosphate, chlorpyrifos, or chlorpyrifos-oxon produced a concentration-dependent increase in the number of locomoting microtubules that detached from the kinesin-coated glass cover slip. Our data suggest that the organophosphates-chlorpyrifos-oxon, chlorpyrifos, and diisopropylfluorophosphate-directly affect kinesin, thereby disrupting kinesin-dependent transport on microtubules. Kinesin-dependent movement of vesicles, organelles, and other cellular components along microtubules is fundamental to the organization of all eukaryotic cells, especially in neurons where organelles and proteins synthesized in the cell body must move down long axons to pre-synaptic sites in nerve terminals. We postulate that disruption of kinesin-dependent intracellular transport could account for some of the long-term effects of organophosphates on the peripheral and central nervous system.
AB - Diisopropylfluorophosphate, originally developed as a chemical warfare agent, is structurally similar to nerve agents, and chlorpyrifos has extensive worldwide use as an agricultural pesticide. While inhibition of cholinesterases underlies the acute toxicity of these organophosphates, we previously reported impaired axonal transport in the sciatic nerves from rats treated chronically with subthreshold doses of chlorpyrifos. Those data indicate that chlorpyrifos (and/or its active metabolite, chlorpyrifos-oxon) might directly affect the function of kinesin and/or microtubules-the principal proteins that mediate anterograde axonal transport. The current report describes in vitro assays to assess the concentration-dependent effects of chlorpyrifos (0-10 μM), chlorpyrifos-oxon (0-10 μM), and diisopropylfluorophosphate (0-0.59 nM) on kinesin-dependent microtubule motility. Preincubating bovine brain microtubules with the organophosphates did not alter kinesin-mediated microtubule motility. In contrast, preincubation of bovine brain kinesin with diisopropylfluorophosphate, chlorpyrifos, or chlorpyrifos-oxon produced a concentration-dependent increase in the number of locomoting microtubules that detached from the kinesin-coated glass cover slip. Our data suggest that the organophosphates-chlorpyrifos-oxon, chlorpyrifos, and diisopropylfluorophosphate-directly affect kinesin, thereby disrupting kinesin-dependent transport on microtubules. Kinesin-dependent movement of vesicles, organelles, and other cellular components along microtubules is fundamental to the organization of all eukaryotic cells, especially in neurons where organelles and proteins synthesized in the cell body must move down long axons to pre-synaptic sites in nerve terminals. We postulate that disruption of kinesin-dependent intracellular transport could account for some of the long-term effects of organophosphates on the peripheral and central nervous system.
KW - Axonal transport
KW - Chlorpyrifos
KW - Chlorpyrifos-oxon
KW - Cholinesterase
KW - DFP
KW - Diisopropylfluorophosphate
KW - Kinesin
KW - Kinesin superfamily (KIF)
KW - Microtubule motility
KW - Microtubules
KW - Organophosphates
KW - Organophosphorus
KW - Pesticides
KW - Tubulin
UR - http://www.scopus.com/inward/record.url?scp=33846025142&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=33846025142&partnerID=8YFLogxK
U2 - 10.1016/j.taap.2006.10.008
DO - 10.1016/j.taap.2006.10.008
M3 - Article
C2 - 17123561
AN - SCOPUS:33846025142
SN - 0041-008X
VL - 218
SP - 20
EP - 29
JO - Toxicology and Applied Pharmacology
JF - Toxicology and Applied Pharmacology
IS - 1
ER -