Dual control of nuclear EIN3 by bifurcate MAPK cascades in C2H4 signalling.
A principal question in MAP kinase (MAPK/MPK) cascade signalling is how similar components dictate different specificity in the information-processing machineries from yeast to humans and plants. In Arabidopsis, how MPK3/6 modulates distinct outputs in diverse signal transduction pathways remains elusive. By combining systematic cellular and genetic screens, here we uncover a previously unexpected MKK9-MPK3/MPK6 cascade promoting ethylene-insensitive 3 (EIN3)-mediated transcription in ethylene signalling. The mkk9 mutant exhibits a broad spectrum of moderate ethylene-insensitive phenotypes, and translocated MKK9 governs nuclear signalling downstream of receptors. Breaking a linear model and conventional MAPK signalling, ethylene inactivates the negative regulator constitutive triple response 1 (CTR1, a Raf-like MAPK kinase kinase (MAPKKK)) to activate the positive MKK9-MPK3/6 cascade. The bifurcate and antagonistic CTR1 and MKK9 pathways are both critical in determining ethylene-signalling specificity through two MAPK phosphorylation sites with opposite effects on EIN3 stability. The results suggest a new paradigm for linking intertwined MAPK cascades to control quantitative responses and specificity in signalling networks.
Yoo
Sang-Dong
SD
Department of Molecular Biology, Massachusetts General Hospital, Department of Genetics, Harvard Medical School, Boston, Massachusetts 02114, USA. yoo@molbio.mgh.harvard.edu
Cho
Young-Hee
YH
Tena
Guillaume
G
Xiong
Yan
Y
Sheen
Jen
J
D017360:Arabidopsis / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins; D004789:Enzyme Activation; D005030:Ethylenes / Q000378:metabolism / Q000494:pharmacology*; D020935:MAP Kinase Signaling System / Q000187:drug effects; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism*; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D030821:Plants, Genetically Modified; D011494:Protein Kinases / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic
D029681:Arabidopsis Proteins; D004268:DNA-Binding Proteins; C106987:EIN3 protein, Arabidopsis; D005030:Ethylenes; D009687:Nuclear Proteins; D014157:Transcription Factors; C036216:ethylene; D011494:Protein Kinases; C477753:CTR1 protein, Arabidopsis; D020928:Mitogen-Activated Protein Kinases; C527379:MKK9 protein, Arabidopsis; D020929:Mitogen-Activated Protein Kinase Kinases