title: Characterization of mouse Rsk4 as an inhibitor of fibroblast growth factor-RAS-extracellular signal-regulated kinase signaling.
abstract: Receptor tyrosine kinase (RTK) signals regulate the specification of a varied array of tissue types by utilizing distinct modules of proteins to elicit diverse effects. The RSK proteins are part of the RTK signal transduction pathway and are thought to relay these signals by acting downstream of extracellular signal-regulated kinase (ERK). In this study we report the identification of ribosomal S6 kinase 4 (Rsk4) as an inhibitor of RTK signals. Among the RSK proteins, RTK inhibition is specific to RSK4 and, in accordance, is dependent upon a region of the RSK4 protein that is divergent from other RSK family members. We demonstrate that Rsk4 inhibits the transcriptional activation of specific targets of RTK signaling as well as the activation of ERK. Developmentally, Rsk4 is expressed in extraembryonic tissue, where RTK signals are known to have critical roles. Further examination of Rsk4 expression in the extraembryonic tissues demonstrates that its expression is inversely correlated with the presence of activated ERK 1/2. These studies demonstrate a new and divergent function for RSK4 and support a role for RSK proteins in the specification of RTK signals during early mouse development.
authors.affiliation: Department of Genetics, Stanford Medical School, Stanford, California 94305, USA.
authors.forename: Andrea Pomrehn
authors.initials: AP
authors.lastname: Myers
authors.forename: Laura B
authors.initials: LB
authors.lastname: Corson
authors.forename: Janet
authors.initials: J
authors.lastname: Rossant
authors.forename: Julie C
authors.initials: JC
authors.lastname: Baker
mesh_terms: D000818:Animals; D001483:Base Sequence; D016373:DNA, Antisense / Q000235:genetics; D005346:Fibroblast Growth Factors / Q000037:antagonists & inhibitors*; D005775:Gastrula / Q000166:cytology / Q000378:metabolism; D020935:MAP Kinase Signaling System; D008648:Mesoderm / Q000166:cytology / Q000378:metabolism; D051379:Mice; D009154:Mutation; D019893:Ribosomal Protein S6 Kinases / Q000235:genetics / Q000378:metabolism*; D020825:T-Box Domain Proteins / Q000037:antagonists & inhibitors / Q000235:genetics; D029867:Xenopus Proteins; D014982:Xenopus laevis; D018631:ras Proteins / Q000037:antagonists & inhibitors*
chemical_list: D016373:DNA, Antisense; D020825:T-Box Domain Proteins; C116765:TBXT protein, Xenopus; D029867:Xenopus Proteins; D005346:Fibroblast Growth Factors; D019893:Ribosomal Protein S6 Kinases; D018631:ras Proteins