Roles of small GTPase Rac1 in the regulation of actin cytoskeleton during dengue virus infection.
BACKGROUND
Increased vascular permeability is a hallmark feature in severe dengue virus (DV) infection, and dysfunction of endothelial cells has been speculated to contribute in the pathogenesis of dengue hemorrhagic fever/dengue shock syndrome (DHF/DSS). Rho-family GTPase Rac1 is a significant element of endothelial barrier function regulation and has been implicated in the regulation of actin remodeling and intercellular junction formation. Yet there is little evidence linking Rac1 GTPase to alteration in endothelial cell function induced by DV infection.


RESULTS
Here, we showed that actin is essential for DV serotype 2 (DV2) entry into and release from ECV304 cells, and Rac1 signaling is involved these processes. At early infection, actin cytoskeleton rearranged significantly during 1 hour post infection, and disrupting actin filament dynamics with jasplakinolide or cytochalasin D reduced DV2 entry. DV2 entry induced reduction of Rac1 activity within 1 hour post infection. The expression of dominant-negative forms of Rac1 established that DV2 entry is negatively regulated by Rac1. At late infection, actin drugs also inhibited the DV2 release and induced accumulation of viral proteins in the cytoplasm. Meanwhile, the activity of Rac1 increased significantly with the progression of DV2 infection and was up-regulated in transfected cells expressing E protein. Confocal microscopy showed that DV2 E protein was closely associated with either actin or Rac1 in DV2-infected cells. The interaction between E protein and actin was further confirmed by co-immunoprecipitation assay.


CONCLUSIONS
These results defined roles for actin integrity in DV2 entry and release, and indicated evidence for the participation of Rac1 signaling pathways in DV2-induced actin reorganizations and E-actin interaction. Our results may provide further insight into the pathogenesis of DHF/DSS.
Wang
Jia-Li
JL
Department of Microbiology, Third Military Medical University, Chongqing, People's Republic of China.
Zhang
Jun-Lei
JL
Chen
Wei
W
Xu
Xiao-Feng
XF
Gao
Na
N
Fan
Dong-Ying
DY
An
Jing
J
D000199:Actins / Q000378:metabolism*; D000330:Aedes; D000818:Animals; D002460:Cell Line; D003716:Dengue Virus / Q000472:pathogenicity*; D042783:Endothelial Cells / Q000821:virology*; D054884:Host-Pathogen Interactions; D047468:Immunoprecipitation; D018613:Microscopy, Confocal; D014759:Viral Envelope Proteins / Q000378:metabolism*; D053586:Virus Internalization; D057074:Virus Release; D020830:rac1 GTP-Binding Protein / Q000378:metabolism*
D000199:Actins; C051821:E-glycoprotein, Dengue virus type 2; D014759:Viral Envelope Proteins; D020830:rac1 GTP-Binding Protein
J Med Virol. 2003 Nov;71(3):463-72
12966555
Lancet. 2007 Nov 10;370(9599):1644-52
17993365
J Virol. 2004 Oct;78(19):10543-55
15367621
EMBO Rep. 2003 Jul;4(7):723-8
12783086
EMBO Rep. 2006 Nov;7(11):1176-81
17028575
Mol Biol Cell. 2005 Feb;16(2):964-75
15601897
Cell. 1992 Aug 7;70(3):401-10
1643658
J Biol Chem. 2007 Aug 10;282(32):23296-305
17562712
J Proteome Res. 2009 May;8(5):2551-62
19281230
Asian Pac J Allergy Immunol. 1996 Dec;14(2):107-13
9177824
J Exp Med. 2003 Apr 7;197(7):823-9
12682107
J Virol. 2004 Jul;78(13):7138-47
15194790
J Virol. 2002 Jun;76(11):5588-97
11991987
Mol Biol Cell. 2000 Jan;11(1):287-304
10637309
Curr Biol. 2000 Nov 2;10(21):1383-6
11084340
Arch Virol. 2008;153(9):1777-81
18695932
J Gen Virol. 2004 Jul;85(Pt 7):1801-1813
15218164
Nature. 2002 Aug 15;418(6899):790-3
12181570
J Gen Virol. 1986 Dec;67 ( Pt 12):2663-72
2432163
Can J Microbiol. 2009 Feb;55(2):139-45
19295646
Virology. 2005 Jan 5;331(1):73-81
15582654
Am J Trop Med Hyg. 1991 Oct;45(4):408-17
1951849
J Biomed Sci. 2009 Feb 04;16:17
19272179
J Infect Dis. 2000 Jan;181(1):2-9
10608744
J Virol. 2007 May;81(9):4881-5
17301152
J Gen Virol. 2008 Feb;89(Pt 2):474-484
18198378
J Virol. 1998 Apr;72(4):2865-70
9525606
J Infect Dis. 2004 Apr 15;189(8):1411-8
15073678
Proc Natl Acad Sci U S A. 2005 Jun 21;102(25):8990-5
15951429
Biochim Biophys Acta. 2008 Mar;1783(3):360-74
18086571
Nat Cell Biol. 2006 Aug;8(8):781-2
16880807
FEMS Immunol Med Microbiol. 2008 Aug;53(3):287-99
18522648
Science. 2006 Sep 15;313(5793):1591-4
16973870
Biochem Biophys Res Commun. 2007 May 11;356(3):763-8
17382900
J Virol. 1999 Apr;73(4):2650-7
10074110
J Gen Virol. 2006 Dec;87(Pt 12):3483-3494
17098962
Arch Virol. 2004 May;149(5):915-27
15098107
J Infect Dis. 2008 Mar 15;197(6):817-24
18269315
J Cell Sci. 2001 Mar;114(Pt 6):1041-52
11228149
J Gen Virol. 2009 Dec;90(Pt 12):2902-2911
19710257
Nature. 1996 Jul 11;382(6587):177-9
8700210
J Clin Virol. 2007 Sep;40(1):50-4
17693133
Cell Host Microbe. 2007 Sep 13;2(3):181-92
18005733
Curr Opin Genet Dev. 1998 Feb;8(1):63-7
9529607
Nat Cell Biol. 2005 Mar;7(3):262-9
15723052