title: Absence of the CAAX endoprotease Rce1: effects on cell growth and transformation.
abstract: After isoprenylation, the Ras proteins and other CAAX proteins undergo two additional enzymatic modifications-endoproteolytic release of the last three amino acids of the protein by the protease Rce1 and methylation of the carboxyl-terminal isoprenylcysteine by the methyltransferase Icmt. This postisoprenylation processing is thought to be important for the association of Ras proteins with membranes. Blocking postisoprenylation processing, by inhibiting Rce1, has been suggested as a potential approach for retarding cell growth and blocking cellular transformation. The objective of this study was to develop a cell culture system for addressing these issues. We generated mice with a conditional Rce1 allele (Rce1(flox)) and produced Rce1(flox/flox) fibroblasts. Cre-mediated excision of Rce1 (thereby producing Rce1(Delta/Delta) fibroblasts) eliminated Ras endoproteolytic processing and methylation and caused a partial mislocalization of truncated K-Ras and H-Ras fusion proteins within cells. Rce1(Delta/Delta) fibroblasts grew more slowly than Rce1(flox/flox) fibroblasts. The excision of Rce1 also reduced Ras-induced transformation, as judged by the growth of colonies in soft agar. The excision of Rce1 from a Rce1(flox/flox) skin carcinoma cell line also significantly retarded the growth of cells, and this effect was exaggerated by cotreatment of the cells with a farnesyltransferase inhibitor. These studies support the idea that interference with postisoprenylation processing retards cell growth, limits Ras-induced transformation, and sensitizes tumor cells to a farnesyltransferase inhibitor.
authors.affiliation: Gladstone Institute of Cardiovascular Disease, University of California, San Francisco, California 94141-9100, USA.
authors.forename: Martin O
authors.initials: MO
authors.lastname: Bergo
authors.forename: Patricia
authors.initials: P
authors.lastname: Ambroziak
authors.forename: Cria
authors.initials: C
authors.lastname: Gregory
authors.forename: Amanda
authors.initials: A
authors.lastname: George
authors.forename: James C
authors.initials: JC
authors.lastname: Otto
authors.forename: Edward
authors.initials: E
authors.lastname: Kim
authors.forename: Hiroki
authors.initials: H
authors.lastname: Nagase
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: Casey
authors.forename: Allan
authors.initials: A
authors.lastname: Balmain
authors.forename: Stephen G
authors.initials: SG
authors.lastname: Young
mesh_terms: D019883:Alkyl and Aryl Transferases / Q000037:antagonists & inhibitors; D000483:Alleles; D020816:Amino Acid Motifs; D000818:Animals; D002455:Cell Division / Q000502:physiology*; D002458:Cell Fractionation; D002471:Cell Transformation, Neoplastic; D002478:Cells, Cultured; D010450:Endopeptidases / Q000235:genetics / Q000378:metabolism*; D051231:Farnesyltranstransferase; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism; D018390:Gene Targeting; D011905:Genes, ras; D006801:Humans; D051379:Mice; D008819:Mice, Nude; D018613:Microscopy, Confocal; D011499:Protein Processing, Post-Translational / Q000502:physiology; D012878:Skin Neoplasms; D014162:Transfection; D014407:Tumor Cells, Cultured; D018631:ras Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D019883:Alkyl and Aryl Transferases; D051231:Farnesyltranstransferase; D010450:Endopeptidases; C491326:RCE1 protein, human; C491324:Rce1 protein, mouse; D018631:ras Proteins