title: STI1 antagonizes cytoskeleton collapse mediated by small GTPase Rnd1 and regulates neurite growth.
abstract: Rnd proteins comprise a branch of the Rho family of small GTP-binding proteins, which have been implicated in rearrangements of the actin cytoskeleton and microtubule dynamics. Particularly in the nervous system, Rnd family proteins regulate neurite formation, dendrite development and axonal branching. A secreted form of the co-chaperone Stress-Inducible Protein 1 (STI1) has been described as a prion protein partner that is involved in several processes of the nervous system, such as neurite outgrowth, neuroprotection, astrocyte development, and the self-renewal of neural progenitor cells. We show that cytoplasmic STI1 directly interacts with the GTPase Rnd1. This interaction is specific for the Rnd1 member of the Rnd family. In the COS collapse assay, overexpression of STI1 prevents Rnd1-plexin-A1-mediated cytoskeleton retraction. In PC-12 cells, overexpression of STI1 enhances neurite outgrowth in cellular processes initially established by Rnd1. Therefore, we propose that STI1 participates in Rnd1-induced signal transduction pathways that are involved in the dynamics of the actin cytoskeleton.
authors.affiliation: Department of Basic Pathology, Universidade Federal do Paraná, Paraná, Brazil; Department of Cell Biology, Universidade Federal do Paraná, Paraná, Brazil.
authors.forename: Luiz Eduardo Rizzo
authors.initials: LE
authors.lastname: de Souza
authors.affiliation: Department of Basic Pathology, Universidade Federal do Paraná, Paraná, Brazil; Department of Cell Biology, Universidade Federal do Paraná, Paraná, Brazil.
authors.forename: Michele Dietrich
authors.initials: MD
authors.lastname: Moura Costa
authors.affiliation: Department of Basic Pathology, Universidade Federal do Paraná, Paraná, Brazil.
authors.forename: Evandro Santos
authors.initials: ES
authors.lastname: Bilek
authors.affiliation: Department of Cell and Developmental Biology, Institute of Biomedical Science, Universidade de São Paulo, São Paulo, Brazil.
authors.forename: Marilene Hohmuth
authors.initials: MH
authors.lastname: Lopes
authors.affiliation: International Research Center, A.C. Camargo Cancer Center, São Paulo, Brazil; National Institute for Translational Neuroscience, São Paulo, Brazil.
authors.forename: Vilma Regina
authors.initials: VR
authors.lastname: Martins
authors.affiliation: Institut für Molekulare Zellbiologie, Westfälische Wilhelms-Universität Münster, Münster, Germany.
authors.forename: Andreas W
authors.initials: AW
authors.lastname: Püschel
authors.affiliation: Department of Basic Pathology, Universidade Federal do Paraná, Paraná, Brazil; Department of Cell Biology, Universidade Federal do Paraná, Paraná, Brazil.
authors.forename: Adriana F
authors.initials: AF
authors.lastname: Mercadante
authors.affiliation: Department of Basic Pathology, Universidade Federal do Paraná, Paraná, Brazil; Department of Cell Biology, Universidade Federal do Paraná, Paraná, Brazil.
authors.forename: Lia Sumie
authors.initials: LS
authors.lastname: Nakao
authors.affiliation: Department of Basic Pathology, Universidade Federal do Paraná, Paraná, Brazil; Department of Cell Biology, Universidade Federal do Paraná, Paraná, Brazil. Electronic address: smzanata@ufpr.br.
authors.forename: Silvio Marques
authors.initials: SM
authors.lastname: Zanata
mesh_terms: D000818:Animals; D019556:COS Cells; D002478:Cells, Cultured; D002522:Chlorocebus aethiops; D003599:Cytoskeleton / Q000378:metabolism*; D006360:Heat-Shock Proteins / Q000502:physiology*; D051379:Mice; D008870:Microtubules / Q000378:metabolism; D016501:Neurites / Q000502:physiology*; D016716:PC12 Cells; D011485:Protein Binding; D051381:Rats; D015398:Signal Transduction / Q000502:physiology; D020741:rho GTP-Binding Proteins / Q000502:physiology*
chemical_list: D006360:Heat-Shock Proteins; C491771:Rnd1 protein, rat; C489790:Stip1 protein, rat; D020741:rho GTP-Binding Proteins
keywords: Hop; Neuritogenesis; Rnd1; STI1