title: The Rho-family GTPase Rac1 regulates integrin localization in Drosophila immunosurveillance cells.
abstract: BACKGROUND
  When the parasitoid wasp Leptopilina boulardi lays an egg in a Drosophila larva, phagocytic cells called plasmatocytes and specialized cells known as lamellocytes encapsulate the egg. The Drosophila β-integrin Myospheroid (Mys) is necessary for lamellocytes to adhere to the cellular capsule surrounding L. boulardi eggs. Integrins are heterodimeric adhesion receptors consisting of α and β subunits, and similar to other plasma membrane receptors undergo ligand-dependent endocytosis. In mammalian cells it is known that integrin binding to the extracellular matrix induces the activation of Rac GTPases, and we have previously shown that Rac1 and Rac2 are necessary for a proper encapsulation response in Drosophila larvae. We wanted to test the possibility that Myospheroid and Rac GTPases interact during the Drosophila anti-parasitoid immune response.
  
  
  RESULTS
  In the current study we demonstrate that Rac1 is required for the proper localization of Myospheroid to the cell periphery of haemocytes after parasitization. Interestingly, the mislocalization of Myospheroid in Rac1 mutants is rescued by hyperthermia, involving the heat shock protein Hsp83. From these results we conclude that Rac1 and Hsp83 are required for the proper localization of Mys after parasitization.
  
  
  CONCLUSIONS
  We show for the first time that the small GTPase Rac1 is required for Mysopheroid localization. Interestingly, the necessity of Rac1 in Mys localization was negated by hyperthermia. This presents a problem, in Drosophila we quite often raise larvae at 29°C when using the GAL4/UAS misexpression system. If hyperthermia rescues receptor endosomal recycling defects, raising larvae in hyperthermic conditions may mask potentially interesting phenotypes.
authors: Institute of Biological and Environmental Sciences, University of Aberdeen, Aberdeen, United Kingdom.
authors: Miguel J
authors: MJ
authors: Xavier
authors: Michael J
authors: MJ
authors: Williams
references: Annu Rev Immunol. 2007;25:697-743
references: 17201680
references: Curr Opin Cell Biol. 2003 Oct;15(5):572-82
references: 14519392
references: Genes Cells. 2005 Aug;10(8):813-23
references: 16098145
references: Cell Tissue Res. 1982;221(3):607-15
references: 6799204
references: Traffic. 2006 Jan;7(1):14-21
references: 16445683
references: Proc Natl Acad Sci U S A. 2009 Mar 24;106(12):4805-9
references: 19261847
references: J Cell Sci. 2007 Apr 1;120(Pt 7):1209-15
references: 17356067
references: Genetics. 2007 Jul;176(3):1579-90
references: 17483425
references: EMBO J. 2004 Jul 7;23(13):2531-43
references: 15192707
references: Nat Rev Mol Cell Biol. 2008 Sep;9(9):690-701
references: 18719708
references: Proc Natl Acad Sci U S A. 2003 Mar 4;100(5):2622-7
references: 12598653
references: EMBO Rep. 2002 Dec;3(12):1195-200
references: 12446570
references: Proc Natl Acad Sci U S A. 2004 Sep 28;101(39):14192-7
references: 15381778
references: PLoS Pathog. 2007 Dec 28;3(12):e203
references: 18166080
references: J Immunol. 2007 Apr 15;178(8):4711-6
references: 17404248
references: Curr Biol. 2007 Apr 3;17(7):649-54
references: 17363253
references: J Cell Biol. 2006 May 8;173(3):405-16
references: 16651377
references: Nat Rev Mol Cell Biol. 2009 Dec;10(12):843-53
references: 19904298
references: Parasitology. 1996 Jan;112 ( Pt 1):135-42
references: 8587797
references: EMBO J. 2004 Oct 13;23(20):3984-94
references: 15457211
references: FEBS Lett. 2008 Jun 18;582(14):2093-101
references: 18460342
references: Cell Microbiol. 2005 Mar;7(3):335-50
references: 15679837
references: Dev Comp Immunol. 1992 Mar-Jun;16(2-3):103-10
references: 1499832
references: Cell Microbiol. 2007 May;9(5):1117-26
references: 17394559
references: J Biol Chem. 1998 Mar 13;273(11):6013-8
references: 9497315
references: J Cell Sci. 2006 Sep 15;119(Pt 18):3723-31
references: 16959902
references: Curr Biol. 2001 Sep 18;11(18):1392-402
references: 11566097
references: Nature. 2002 Mar 28;416(6879):438-42
references: 11919634
references: Physiol Rev. 2011 Jan;91(1):119-49
references: 21248164
references: Dev Biol. 2001 Feb 15;230(2):243-57
references: 11161576
references: Dev Biol. 2002 Mar 1;243(1):65-80
references: 11846478
references: J Cell Sci. 2006 May 15;119(Pt 10):2015-24
references: 16621891
references: J Endocrinol. 2011 May;209(2):139-51
references: 21307119
references: Traffic. 2010 Aug;11(8):1107-18
references: 20477989
references: Mol Biol Cell. 2006 Aug;17(8):3494-507
references: 16687576
references: Curr Opin Immunol. 2004 Feb;16(1):10-5
references: 14734104
references: Insect Biochem Mol Biol. 2005 Feb;35(2):93-103
references: 15681220
references: EMBO J. 2002 Nov 15;21(22):6125-35
references: 12426384
references: Mech Dev. 2001 Nov;109(1):69-77
references: 11677054
references: Pigment Cell Melanoma Res. 2011 Apr;24(2):282-94
references: 21087420
references: J Insect Physiol. 2005 Feb;51(2):161-70
references: 15749101
references: Traffic. 2004 Jan;5(1):20-36
references: 14675422
references: Nature. 2002 Mar 28;416(6879):442-7
references: 11919635