Symmetry breaking and polarization of the C. elegans zygote by the polarity protein PAR-2.
Polarization of the C. elegans zygote is initiated by ECT-2-dependent cortical flows, which mobilize the anterior PAR proteins (PAR-3, PAR-6 and PKC-3) away from the future posterior end of the embryo marked by the sperm centrosome. Here, we demonstrate the existence of a second, parallel and redundant pathway that can polarize the zygote in the absence of ECT-2-dependent cortical flows. This second pathway depends on the polarity protein PAR-2. We show that PAR-2 localizes to the cortex nearest the sperm centrosome even in the absence of cortical flows. Once on the cortex, PAR-2 antagonizes PAR-3-dependent recruitment of myosin, creating myosin flows that transport the anterior PAR complex away from PAR-2 in a positive-feedback loop. We propose that polarity in the C. elegans zygote is initiated by redundant ECT-2- and PAR-2-dependent mechanisms that lower PAR-3 levels locally, triggering a positive-feedback loop that polarizes the entire cortex.
Zonies
Seth
S
Department of Molecular Biology and Genetics, Howard Hughes Medical Institute, Center for Cell Dynamics, Johns Hopkins School of Medicine, PCTB 706, Baltimore, MD 21205, USA.
Motegi
Fumio
F
Hao
Yingsong
Y
Seydoux
Geraldine
G
D000483:Alleles; D000595:Amino Acid Sequence; D000818:Animals; D030801:Animals, Genetically Modified; D019521:Body Patterning / Q000235:genetics*; D017173:Caenorhabditis elegans / Q000196:embryology / Q000235:genetics; D029742:Caenorhabditis elegans Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D016764:Cell Polarity / Q000235:genetics*; D004625:Embryo, Nonmammalian; D017238:Genes, Helminth / Q000502:physiology; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D020662:Guanine Nucleotide Exchange Factors / Q000235:genetics; D008969:Molecular Sequence Data; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction / Q000235:genetics / Q000502:physiology; D015053:Zygote / Q000254:growth & development* / Q000378:metabolism / Q000502:physiology
D029742:Caenorhabditis elegans Proteins; C507872:Ect-2 protein, C elegans; D020662:Guanine Nucleotide Exchange Factors; C087977:par-2 protein, C elegans; D049452:Green Fluorescent Proteins
Cell. 1995 May 19;81(4):611-20
7758115
Nature. 2000 Nov 2;408(6808):89-92
11081513
Development. 2003 Apr;130(7):1255-65
12588843
Dev Cell. 2007 Nov;13(5):609-622
17981131
Dev Cell. 2003 Mar;4(3):333-44
12636915
Curr Biol. 2004 May 25;14(10):851-62
15186741
Nat Cell Biol. 2006 Sep;8(9):978-85
16921365
Curr Biol. 2001 Feb 6;11(3):171-6
11231151
Curr Biol. 2001 Apr 3;11(7):482-8
11412997
Dev Cell. 2004 Jun;6(6):845-54
15177032
Nature. 1998 Oct 29;395(6705):854
9804418
J Cell Biol. 2007 Nov 5;179(3):397-402
17967950
Nat Rev Mol Cell Biol. 2003 Jun;4(6):446-56
12778124
Dev Cell. 2002 Nov;3(5):659-71
12431373
Curr Opin Genet Dev. 1996 Aug;6(4):408-15
8791533
Nature. 2002 Dec 12;420(6916):629-35
12478284
Cell. 2000 May 12;101(4):345-8
10830161
Dev Cell. 2006 Feb;10(2):199-208
16459299
EMBO Rep. 2005 Dec;6(12):1163-8
16170304
Dev Cell. 2004 Sep;7(3):413-24
15363415
Cold Spring Harb Perspect Biol. 2009 Oct;1(4):a003400
20066102
J Biol Chem. 1985 Aug 25;260(18):10027-31
3839510
BMC Genomics. 2005 Sep 12;6:118
16156901
Nature. 2003 Jan 16;421(6920):231-7
12529635
Development. 2003 Nov;130(22):5339-50
13129846
Development. 2006 Sep;133(18):3507-16
16899536
Dev Biol. 1998 Aug 15;200(2):212-24
9705228
Genetics. 1974 May;77(1):71-94
4366476
Curr Biol. 2003 Jun 17;13(12):1029-37
12814548
Curr Biol. 2009 May 12;19(9):723-9
19375318
J Cell Biol. 1999 Jul 26;146(2):439-51
10427096
Science. 2006 Sep 1;313(5791):1298-301
16873611
Dev Biol. 2000 Dec 15;228(2):225-38
11112326
Curr Biol. 2004 Apr 20;14(8):736-41
15084291