title: Human papillomavirus type 16 E5 protein colocalizes with the antiapoptotic Bcl-2 protein.
abstract: Human papillomavirus type 16 E5 protein contributes to cellular transformation by increasing the mitogenic stimulus from growth factor receptors to the nucleus. In order to study the biological mechanisms of the E5 protein we performed site-directed mutagenesis of the E5 gene. Wild-type as well as mutant E5 proteins were transiently expressed in human cervical epithelial cells, and cell morphology, expression of proteins involved in cell adhesion, and localization of the different proteins were studied. Little differences in cell morphology or expression kinetics were observed between the different E5 proteins, except for relocalization of a mutant E5 protein where a hydrophobic leucine membrane anchor was mutated to positively charged amino acids. This mutant E5 protein localized to lamellipodia, which are motility-associated structures at the leading edge of motile cells. In our experimental conditions, 100% of E5-expressing epithelial cells died by four days of expression, possibly due to toxicity or disturbance of the membrane compartment by the E5 protein. Most interestingly, a remarkable colocalization of the E5 protein with the Bcl-2 antiapoptotic protein on intracellular membranes was established.
authors.affiliation: Department of Virology, Helsinki University Central Hospital, University of Helsinki, Helsinki, Finland. eeva.auvinen@helsinki.fi
authors.forename: E
authors.initials: E
authors.lastname: Auvinen
authors.forename: A
authors.initials: A
authors.lastname: Alonso
authors.forename: P
authors.initials: P
authors.lastname: Auvinen
mesh_terms: D019943:Amino Acid Substitution; D002448:Cell Adhesion; D016923:Cell Death; D048430:Cell Shape; D004847:Epithelial Cells / Q000737:chemistry / Q000166:cytology / Q000378:metabolism; D022001:Focal Adhesions; D017930:Genes, Reporter; D005814:Genes, Viral; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D007425:Intracellular Membranes / Q000378:metabolism*; D008856:Microscopy, Fluorescence; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D009856:Oncogene Proteins, Viral / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D021381:Protein Transport; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism*; D011554:Pseudopodia / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D020830:rac1 GTP-Binding Protein / Q000378:metabolism; D000086082:Viroporin Proteins
chemical_list: D049452:Green Fluorescent Proteins; D009856:Oncogene Proteins, Viral; D019253:Proto-Oncogene Proteins c-bcl-2; D011993:Recombinant Fusion Proteins; D020830:rac1 GTP-Binding Protein; C054859:oncogene protein E5, Human papillomavirus type 16; D000086082:Viroporin Proteins