%0 Journal Article
%T Microtubules as a Critical Target for Arsenic Toxicity in Lung Cells in Vitro and in Vivo
%A Yinzhi Zhao
%A Paul Toselli
%A Wande Li
%J International Journal of Environmental Research and Public Health
%D 2012
%I MDPI AG
%R 10.3390/ijerph9020474
%X To understand mechanisms for arsenic toxicity in the lung, we examined effects of sodium m-arsenite (As 3+) on microtubule (MT) assembly in vitro (0¨C40 ¦ÌM), in cultured rat lung fibroblasts (RFL6, 0¨C20 ¦ÌM for 24 h) and in the rat animal model (intratracheal instillation of 2.02 mg As/kg body weight, once a week for 5 weeks). As 3+ induced a dose-dependent disassembly of cellular MTs and enhancement of the free tubulin pool, initiating an autoregulation of tubulin synthesis manifest as inhibition of steady-state mRNA levels of ¦ÂI-tubulin in dosed lung cells and tissues. Spindle MT injuries by As 3+ were concomitant with chromosomal disorientations. As 3+ reduced the binding to tubulin of [ 3H]N-ethylmaleimide (NEM), an -SH group reagent, resulting in inhibition of MT polymerization in vitro with bovine brain tubulins which was abolished by addition of dithiothreitol (DTT) suggesting As 3+ action upon tubulin through -SH groups. In response to As 3+, cells elevated cellular thiols such as metallothionein. Taxol, a tubulin polymerization agent, antagonized both As 3+ and NEM induced MT depolymerization. MT¨Cassociated proteins (MAPs) essential for the MT stability were markedly suppressed in As 3+-treated cells. Thus, tubulin sulfhydryls and MAPs are major molecular targets for As 3+ damage to the lung triggering MT disassembly cascades.
%K trivalent arsenic (As3+)
%K microtubules (MTs)
%K tubulin
%K tubulin mRNA
%K tubulin sulfhydryl groups (-SH)
%K microtubule-associated proteins (MAPs)
%K chromosomal disorientations
%K metallothionein
%K taxol
%U http://www.mdpi.com/1660-4601/9/2/474