Isolation and characterisation of the human rab18 gene after stimulation of endothelial cells with histamine

Here me report the isolation of a cDNA encoding the complete human rab18 pr otein from histamine-stimulated endothelial cells using differential displa y. The amino acid sequence showed 98% homology with the previously isolated mouse rab18 protein, which is implicated in apical/basolateral endocytosis . Northern blot analysis revealed two transcripts (2.5 kb and 1 kb) ubiquit ously expressed in all examined organs, as well as in human umbilical vein endothelial and aortic cells. In blood cells rab18 transcripts were hardly detectable. The histamine-induced time-dependent increase of rab18 mRNA exp ression in human umbilical vein endothelial cells and peripheral blood mono nuclear cells indicates for the first time a link between receptor-mediated signal transduction and the regulation of rab gene expression. This findin g might also imply a role for rab proteins in inflammation. (C) 2000 Federa tion of European Biochemical Societies.