title: Analysis of Rit signaling and biological activity.
abstract: Rit (Ras-like expressed in many tissues) is the founding member of a novel subgroup within the larger Ras superfamily of small GTP-binding proteins. Although Rit shares more than 50% amino acid identity with Ras, it contains a unique effector domain in common with the closely related Rin and Drosophila Ric proteins and lacks the C-terminal lipidation motifs critical for the membrane association and biological activity of many Ras proteins. Interestingly, whereas Rit has only modest transforming ability when assayed in NIH 3T3 cells, Rit exhibits neuronal differentiation activities comparable to those of oncogenic mutants of Ras when assayed in PC12 and other neuronal cell lines. This cell-type specificity is explained in part by the ability of Rit to selectively activate the neuronal Raf isoform, B-Raf. Importantly, Rit seems to play a critical role in neurotrophin-mediated MAP kinase signaling, because Rit gene silencing significantly alters NGF-dependent MAP kinase signaling and neuronal differentiation. In this chapter, we discuss the reagents and methods used to characterize Rit-mediated signaling to MAP kinase-signaling pathways to determine the extracellular stimuli that regulate Rit activation and to characterize Rit-induced neuronal differentiation.
authors.affiliation: Department of Molecular and Cellular Biochemistry, University of Kentucky College of Medicine, Lexington, Kentucky, USA.
authors.forename: Douglas A
authors.initials: DA
authors.lastname: Andres
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Rudolph
authors.forename: Tomoko
authors.initials: T
authors.lastname: Sengoku
authors.forename: Geng-Xian
authors.initials: GX
authors.lastname: Shi
mesh_terms: D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects; D002478:Cells, Cultured; D006160:Guanosine Triphosphate / Q000378:metabolism; D020935:MAP Kinase Signaling System / Q000502:physiology; D009474:Neurons / Q000166:cytology; D048493:Proto-Oncogene Proteins B-raf / Q000378:metabolism; D015398:Signal Transduction; D009435:Synaptic Transmission / Q000187:drug effects; D020798:Two-Hybrid System Techniques; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism; D048490:raf Kinases / Q000378:metabolism; D018631:ras Proteins / Q000235:genetics / Q000502:physiology*
chemical_list: D006160:Guanosine Triphosphate; D048493:Proto-Oncogene Proteins B-raf; D048490:raf Kinases; D048051:p38 Mitogen-Activated Protein Kinases; C472865:Rit1 protein, mouse; D018631:ras Proteins