Ea. Hixenbaugh et al., STIMULATED NEUTROPHILS INDUCE MYOSIN LIGHT-CHAIN PHOSPHORYLATION AND ISOMETRIC TENSION IN ENDOTHELIAL-CELLS, American journal of physiology. Heart and circulatory physiology, 42(2), 1997, pp. 981-988
The mechanism or mechanisms by which polymorphonuclear leukocytes (PMN
) penetrate junctions between neighboring endothelial cells (EC) to tr
averse endothelial barriers remain unresolved. We report that chemoatt
ractant-stimulated PMN induce a coordinate increase in both phosphoryl
ation of serine 19 and threonine 18 of EC myosin regulatory light chai
ns and isometric tension generation by EC monolayers. Unstimulated PMN
had no effect on either parameter. These findings, coupled with our p
revious report (Huang et al., J. Cell Biol. 120: 1371-1380, 1993) that
chemoattractant-stimulated PMN cause a rise in EC cytosolic free Ca2, provide strong presumptive evidence that myosin light chain kinase i
s the EC enzyme responsible for initiating myosin light chain phosphor
ylation, EC contraction, and isometric tension generation in response
to chemoattractant stimulated PMN. We suggest that, by inducing phosph
orylation of EC cytoskeletal proteins, chemoattractant-stimulated PMN
induce EC to open their intercellular junctions, thereby facilitating
transendothelial movement of these leukocytes.