title: A differentiation switch for genetically modified hepatocytes.
abstract: The hepatocyte growth factor (HGF) receptor mediates a two-sided response-cell proliferation and differentiation. This process, defined as "branching morphogenesis," involves cell scatter and redistribution to form ramified hollow tubules within the extracellular matrix, and protection from apoptosis. We have fused the intracellular domain of the HGF receptor (HGFR) with three FK506-binding protein (FKBP) domains and a membrane-targeting signal. This molecule (FKBP-HGFR) dimerizes after administration of a bifunctional ligand specific for FKBP domains. We show that, in mouse hepatocyte progenitors, FKBP-HGFR dimerization elicits the differentiative side of the HGF response, including cell scatter, morphogenesis, and protection from apoptosis. Surprisingly, FKBP-HGFR does not induce cell proliferation. We could correlate the segregation of the differentiative response with a distinctive signaling kinetic of FKBP-HGFR: a) reduced and prolonged tyrosine kinase activation; and b) low early peak of MAP kinase activation (a log lower than the peak induced by the wild-type receptor), followed by a sustained activation over 6 h. These data show that the biological response triggered by the HGFR can be dissected on the basis of the quantitative signaling profile, and that FKBP-HGFR may be used to control selectively the differentiation of hepatocytes, without promoting cell expansion.
authors.affiliation: Institute for Cancer Research and Treatment, University of Torino Medical School, 10060 Candiolo-Torino, Italy. cboccaccio@ircc.unito.it
authors.forename: Carla
authors.initials: C
authors.lastname: Boccaccio
authors.forename: Margherita
authors.initials: M
authors.lastname: Ando'
authors.forename: Paolo M
authors.initials: PM
authors.lastname: Comoglio
mesh_terms: D000818:Animals; D017209:Apoptosis; D002454:Cell Differentiation; D002455:Cell Division; D002460:Cell Line; D002465:Cell Movement; D003599:Cytoskeleton / Q000648:ultrastructure; D019281:Dimerization; D022781:Hepatocytes / Q000166:cytology* / Q000378:metabolism; D007700:Kinetics; D008099:Liver / Q000254:growth & development; D051379:Mice; D008954:Models, Biological; D009024:Morphogenesis; D019859:Proto-Oncogene Proteins c-met / Q000235:genetics* / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000502:physiology; D015398:Signal Transduction; D013234:Stem Cells / Q000166:cytology / Q000378:metabolism; D022021:Tacrolimus Binding Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D011993:Recombinant Fusion Proteins; D019859:Proto-Oncogene Proteins c-met; D022021:Tacrolimus Binding Proteins