DIRECT EFFECT OF THE NEUROTOXICANT ACRYLAMIDE ON KINESIN-BASED MICROTUBULE MOTILITY

Acrylamide (ACR) is an environmental toxicant and prototypic tool for studying mechanisms of peripheral neuropathies, Reductions in fast ant erograde axonal transport (faAXT) are thought to be a critical step le ading to axonal degeneration, Kinesin and microtubules (MT) were evalu ated as molecular sites of action using an in vitro MT motility assay, The number of locomoting MT which lifted from a bed of kinesin (MT de tachments or MTD), increased from 7% in controls to 80, 89, and 100% f ollowing preincubation of kinesin (37 degrees C, 20 min) with 0.1, 0.5 , or 1.0 mM ACR, respectively; rates were variably reduced by as much as 20%, Similar alterations were observed with N-ethylmaleimide, A non -neurotoxic analogue, propionamide (1 mM), had no effect on either par ameter, Preincubation of taxol-stabilized MT with ACR produced a dose- dependent increase in MTD but no changes in rate, We conclude that kin esin and MT are covalently modified by ACR resulting in reduced affini ty for each other, The greater sensitivity of kinesin indicates that a primary cause of transient, ACR-induced reductions in faAXT is covale nt modification of kinesin, Such reductions in faAXT may be sufficient to produce axonal degeneration, Further, ACR may prove useful as a ph armacological tool to decipher the complex mechanics of kinesin-MT int eractions. (C) 1996 Wiley-Liss, Inc.