Vertebrate non muscle myosin II have been shown to play important roles in a variety of cellular processes. The aim of the present work was to address the role of myosin II in the cell volume homeostasis at the epithelial level. The study was carried out on a model salt transport epithelium, the intestine of European eel, which is able to perform a Regulatory Volume Increase accounted by the stimulation of the luminal Na+-K+-2Cl- cotransporter following an hypertonic stress. Short circuit current measurements and confocal laser scanning microscopy were applied. The hypertonicity induced stimulation of Na+-K+-2Cl- was sensitive to bebblistatin, specific inhibitor of myosin II, and ML-7, inhibitor of myosin light chain kinase, suggesting its dependence from myosin-driven mechanisms. It was also sensitive to Rho family small GTPases and ROK, known regulators of myosin II phosphorylation. Moreover, the process was also sensitive to p38 MAPK and c-JNK but not ERK1/2 inhibition. A specific myosin labelling was observed as immunofluorescence spots associated to the cortical F-actin cytoskeleton at the junctional level. Hypertonicity increased myosin II spots thickness was sensitive to Clostridium difficile toxin B. In conclusion, myosin II recruitment to the junctional region and a myosin dependent upregulation of Na+-K+-2Cl-, both dependent on small Rho GTPase, could be the expression of the multiple roles of myosin II in the response of the epithelium to hypertonicity.
Role of Myosin II in the response to hypertonic stress: a study in a native intestinal epithelium
LIONETTO, Maria Giulia;GIORDANO, Maria Elena;SCHETTINO, Trifone
2009-01-01
Abstract
Vertebrate non muscle myosin II have been shown to play important roles in a variety of cellular processes. The aim of the present work was to address the role of myosin II in the cell volume homeostasis at the epithelial level. The study was carried out on a model salt transport epithelium, the intestine of European eel, which is able to perform a Regulatory Volume Increase accounted by the stimulation of the luminal Na+-K+-2Cl- cotransporter following an hypertonic stress. Short circuit current measurements and confocal laser scanning microscopy were applied. The hypertonicity induced stimulation of Na+-K+-2Cl- was sensitive to bebblistatin, specific inhibitor of myosin II, and ML-7, inhibitor of myosin light chain kinase, suggesting its dependence from myosin-driven mechanisms. It was also sensitive to Rho family small GTPases and ROK, known regulators of myosin II phosphorylation. Moreover, the process was also sensitive to p38 MAPK and c-JNK but not ERK1/2 inhibition. A specific myosin labelling was observed as immunofluorescence spots associated to the cortical F-actin cytoskeleton at the junctional level. Hypertonicity increased myosin II spots thickness was sensitive to Clostridium difficile toxin B. In conclusion, myosin II recruitment to the junctional region and a myosin dependent upregulation of Na+-K+-2Cl-, both dependent on small Rho GTPase, could be the expression of the multiple roles of myosin II in the response of the epithelium to hypertonicity.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
