Methylmercury disassembles microtubules and induces apoptosis in P19 embryonal carcinoma cells.

Abstract

The relationship between the sensitivity of microtubules (Mts) to MeHg-induced disassembly and the extent apoptosis was examined in undifferentiated and neuronally differentiated P19 cells. The extent of Mt disassembly was examined qualitatively by immunofluorescence microscopy and quantitatively by polymer and soluble protein extractions, followed by dot blotting or by SDS-PAGE and western blotting. In both undifferentiated and neuronally differentiated P19 cells MeHg treatments disassembled Mts in a time- and dose-dependent manner, as assessed by immunofluorescence microscopy. However, when the extent of Mt disassembly was assessed by quantitative dot blotting or by SDS-PAGE followed by western blotting there was no change observed in the amount of tubulin in the polymer and soluble fractions between control and MeHg-treated samples. These data suggest that MeHg treatments disassemble Mts into a form which is not extractable as soluble protein. MeHg-induced apoptosis was assessed using a combination of assays including single cell gel electrophoresis (Comet assay), TUNEL, conventional agarose gel electrophoresis, and pulsed field gel electrophoresis. (Abstract shortened by UMI.)