title: MAPK signaling in plant hormone ethylene signal transduction.
abstract: The signal transduction pathway of the plant stress and defense hormone, ethylene, has been extensively elucidated using the plant genetic model Arabidopsis over the last two decades. Among others, a MAPKKK CTR1 was identified as a negative regulator that has led to the speculation of MAPK involvement in ethylene signaling. However, it remained unclear how the MAPK modules acting downstream of the receptors to mediate ethylene signaling. We have recently presented new evidence that the MKK9-MPK3/6 modules identified by combined functional genomic and genetic screens mediate ethylene signaling, which is negatively regulated by the genetically identified CTR1-dependent cascades. Our genetic studies show consistently that the MKK9-MPK3/MPK6 modules act downstream of the ethylene receptors. Biochemical and transgenic analyses further demonstrated that the positive-acting and negative-acting MAPK activities are integrated and act simultaneously to control the key transcription factor EIN3 through dual phosphorylations to regulate the EIN3 protein stability and downstream transcription cascades. This study has revealed a novel molecular mechanism that defines the specificity of complex MAPK signaling. Comprehensive elucidation of MAPK cascades and the underlying molecular mechanisms would provide more precise explanations for how plant cells utilize MAPK cascades to control specific downstream outputs in response to distinct stimuli.
authors.affiliation: Department of Biological Science; College of Natural Science; SungKyunKwan University; Suwon, Gyeonggi-do Korea.
authors.forename: Sang-Dong
authors.initials: SD
authors.lastname: Yoo
authors.forename: Jen
authors.initials: J
authors.lastname: Sheen
references.citation: Plant Cell. 2007 Feb;19(2):509-23
references.pmid: 17307926
references.citation: Nature. 2008 Feb 14;451(7180):789-95
references.pmid: 18273012
references.citation: Proc Natl Acad Sci U S A. 2003 Jan 7;100(1):352-7
references.pmid: 12509505
references.citation: Science. 2004 Nov 26;306(5701):1513-5
references.pmid: 15567852
references.citation: Cell. 2003 Dec 12;115(6):667-77
references.pmid: 14675532
references.citation: Genes Dev. 1998 Dec 1;12(23):3703-14
references.pmid: 9851977
references.citation: Science. 1995 Dec 15;270(5243):1809-11
references.pmid: 8525372
references.citation: Science. 1993 Oct 22;262(5133):539-44
references.pmid: 8211181
references.citation: J Biol Chem. 2003 Sep 5;278(36):34725-32
references.pmid: 12821658
references.citation: Proc Natl Acad Sci U S A. 2004 Apr 27;101(17):6803-8
references.pmid: 15090654
references.citation: Science. 1995 Sep 22;269(5231):1712-4
references.pmid: 7569898
references.citation: Cell. 1997 Jun 27;89(7):1133-44
references.pmid: 9215635
references.citation: Cell. 1993 Feb 12;72(3):427-41
references.pmid: 8431946
references.citation: EMBO J. 2003 Mar 17;22(6):1282-8
references.pmid: 12628921
references.citation: Proc Natl Acad Sci U S A. 1998 May 12;95(10):5812-7
references.pmid: 9576967
references.citation: FEBS Lett. 2000 May 26;474(1):29-32
references.pmid: 10828445
references.citation: Science. 1988 Aug 26;241(4869):1086-9
references.pmid: 17747490
references.citation: Nat Protoc. 2007;2(7):1565-72
references.pmid: 17585298
references.citation: Plant Cell. 1998 Aug;10(8):1321-32
references.pmid: 9707532
references.citation: Plant J. 2003 Jan;33(2):221-33
references.pmid: 12535337
references.citation: Cell. 1998 Jul 24;94(2):261-71
references.pmid: 9695954
references.citation: Proc Natl Acad Sci U S A. 1998 Apr 28;95(9):5401-6
references.pmid: 9560288
references.citation: Cell. 2003 Dec 12;115(6):679-89
references.pmid: 14675533
references.citation: Science. 1999 Jun 25;284(5423):2148-52
references.pmid: 10381874
references.citation: Nature. 2003 Oct 2;425(6957):521-5
references.pmid: 14523448