title: Pituicyte stellation is prevented by RhoA-or Cdc42-dependent actin polymerization.
abstract: Our aim was to shed light on different steps leading from metabotropic receptor activation to changes in cell shape, such as those that characterize the morphological plasticity of neurohypophysial astrocytes (pituicytes). Using explant cultures of adult rat pituicytes, we have previously established that adenosine A1 receptor activation induces stellation via inhibition of RhoA monomeric GTPase and subsequent disruption of actin stress fibers. Here, we rule out RhoA phosphorylation as a mechanism for that inhibition. Rather, our results are more consistent with involvement of a GTPase-activating protein (GAP). siRNA and pull-down experiments suggest that a step downstream of RhoA might involve Cdc42, another GTPase of the Rho family. However, RhoA activation, e.g., in the presence of serum, induces stress fibers, whereas direct Cdc42 activation appears to confine actin within a submembrane - i.e., cortical - network, which also prevents stellation. Therefore, we propose that RhoA may activate Cdc42 in parallel with an effector, such as p160Rho-kinase, that induces and maintains actin stress fibers in a dominant fashion. Rac1 is not involved in the stellation process per se but appears to induce a dendritogenic effect. Ultimately, it may be stated that pituicyte stellation is inducible upon mere actin depolymerization, and preventable upon actin organization, be it in the form of stress fibers or in a cortical configuration.
authors: CNRS UMR 6548, Laboratoire de Physiologie Cellulaire et Moléculaire Faculté des Sciences, Université de Nice-Sophia Antipolis, Nice Cedex 2 06108, France.
authors: Lia
authors: L
authors: Rosso
authors: Patricia M
authors: PM
authors: Pierson
authors: Claire
authors: C
authors: Golfier
authors: Brigitta
authors: B
authors: Peteri-Brunbäck
authors: Christophe
authors: C
authors: Deroanne
authors: Ellen
authors: E
authors: Van Obberghen-Schilling
authors: Jean-Marc
authors: JM
authors: Mienville
mesh_terms: D000199:Actins / Q000378:metabolism*; D000241:Adenosine / Q000494:pharmacology; D000818:Animals; D001253:Astrocytes / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D002478:Cells, Cultured; D003599:Cytoskeleton / Q000187:drug effects / Q000378:metabolism; D019281:Dimerization; D009473:Neuronal Plasticity / Q000502:physiology; D010902:Pituitary Gland / Q000166:cytology*; D034622:RNA Interference; D051381:Rats; D017208:Rats, Wistar; D014162:Transfection; D020764:cdc42 GTP-Binding Protein / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D020742:rhoA GTP-Binding Protein / Q000235:genetics / Q000378:metabolism / Q000502:physiology*
chemical_list: D000199:Actins; D020764:cdc42 GTP-Binding Protein; D020742:rhoA GTP-Binding Protein; D000241:Adenosine
references: Eur J Neurosci. 2002 Dec;16(12):2324-32
references: 12492427
references: J Biol Chem. 2003 May 23;278(21):19023-31
references: 12654918
references: Am J Physiol Lung Cell Mol Physiol. 2004 Dec;287(6):L1091-7
references: 15286003
references: J Cell Sci. 2005 Mar 15;118(Pt 6):1173-83
references: 15728253
references: J Neurochem. 1978 Dec;31(6):1479-90
references: 233099
references: Trends Neurosci. 1996 Aug;19(8):363-7
references: 8843607
references: Science. 1998 Jan 23;279(5350):509-14
references: 9438836
references: Cell. 1999 Aug 20;98(4):487-99
references: 10481913
references: Circ Res. 2005 Jun 10;96(11):1152-60
references: 15890975
references: Mol Biol Cell. 2004 Feb;15(2):520-31
references: 14617808
references: Blood. 1992 Dec 1;80(11):2911-9
references: 1333304
references: Curr Biol. 1997 Sep 1;7(9):629-37
references: 9285711
references: Neurosci Lett. 1997 Apr 18;226(1):41-4
references: 9153637
references: Neurosci Res. 1999 Apr;33(4):299-306
references: 10401983
references: J Chem Neuroanat. 1999 May;16(3):203-21
references: 10422739
references: Glia. 2002 Jun;38(4):351-62
references: 12007147
references: J Cell Sci. 2004 Sep 1;117(Pt 19):4559-69
references: 15316070
references: Brain Res. 1998 Aug 31;804(1):63-71
references: 9729281
references: EMBO J. 2002 May 15;21(10):2373-82
references: 12006490
references: Mol Pharmacol. 2000 Nov;58(5):903-10
references: 11040036
references: J Cell Sci. 1999 Mar;112 ( Pt 6):947-56
references: 10036244
references: Hoppe Seylers Z Physiol Chem. 1980 Nov;361(11):1615-28
references: 6256277
references: EMBO J. 1996 Feb 1;15(3):510-9
references: 8599934
references: Exp Cell Res. 1998 Dec 15;245(2):252-62
references: 9851865