BEHAVIOR OF THE SMALL GTP-BINDING PROTEIN RAB6 IN THE LIVER OF NORMALRATS AND RATS PRESENTING AN ACUTE INFLAMMATORY REACTION

While it is known that the small GTP-binding protein rab6 is localized in vitro to the Golgi apparatus of several mammalian cells, its behav iour in vivo has not yet been investigated. The aim of this work was t o compare by immunocytochemistry and immunoblotting the distribution o f rab6 in hepatocytes from normal rats and from rats with an acute inf lammatory reaction, a circumstance where the synthesis and secretion o f plasma proteins by the hepatocytes is increased and which is accompa nied by several changes in the Golgi apparatus. Our results show that in normal rats, rab6 was present in all hepatocytes irrespective of th e location of the cell in the hepatic lobule. At the ultrastructural l evel, rab6 was mainly visible on the three Golgi saccules, but in some cells it appeared to be absent in saccules corresponding to the cis o r the trans saccule. The inflammatory reaction was accompanied by an i ncrease of the immunocytochemical labelling at the light and electron microscopy levels. However, by immunoblotting, no differences in the t otal amount of rab6, nor in its subcellular distribution were found in liver cells after acute inflammatory reaction. These results demonstr ate that rab6 is restricted in vivo to the Golgi apparatus and that no significant redistribution occurs during an acute inflammatory reacti on.