Am. J. Respir. Cell Mol. Biol., Vol 16, No. 2, 02 1997, 127-132.
Changes in mononuclear phagocyte microtubules after endotoxin stimulation. II. Changes in microtubule composition
JN Allen, Z Liao, SA Moore and MD Wewers
Division of Pulmonary and Critical Care Medicine, Ohio State University, Columbus, USA.
Microtubules are integral components of the cytoskeleton of human cells and
are composed of alpha- and beta-tubulin as well as a variable number of
microtubule-associated proteins. In monocytes and macrophages, microtubules
bind endotoxin and partly regulate endotoxin- induced inflammatory events
such as cytokine production. Endotoxin causes a rapid alteration in
monocyte microtubule stability. To characterize the effect of endotoxin on
mononuclear phagocyte microtubule composition, Western blots and flow
cytometry were performed on human monocytes and the
monocyte/macrophage-like cell line THP-1. Compared to unstimulated
monocytes, monocytes stimulated with endotoxin for 18 h had increased
quantities of alpha-, beta-, and tyrosinated alpha-tubulin as well as
microtubule-associated protein-2. PMA-differentiated THP-1 cells had
increased levels of alpha-tubulin, beta-tubulin, microtubule-associated
protein-5, microtubule-associated protein-2, and tau after endotoxin
stimulation. These results indicate that endotoxin can alter mononuclear
phagocyte microtubules by causing an increase in certain microtubule
component proteins.
