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. 2019 May 14;70(13):3415–3424. doi: 10.1093/jxb/erz233

Fig. 3.

Fig. 3.

A model of MED25 regulation of different stages of JA signaling. In response to wounding or other stimulus, MED25 coordinates the actions of multiple components of JA signaling to regulate the expression of JA-responsive genes such as LOX. In the absence of stimulus, MED25 interacts with COI1 at the LOX promoter, whereas JAZ proteins interact with MYC2 and repress MYC2 activity. The expression level of LOX is low. In response to stimulus, MED25 promotes JA-triggered interaction of COI1 and JAZ proteins and subsequent degradation of JAZ repressors, which released the activity of MYC2. Then, MED25 interacts with MYC2 and recruits the coactivator HAC1 to activate LOX expression. The MYC2–MED25 functional complex activates the expression of MTBs, which form an autoregulatory negative feedback circuit to terminate JA signaling and thus reduce the LOX expression level. COI1, CORONATINE INSENSITIVE 1; JA, jasmonate; JA-Ile, jasmonoyl-isoleucine; JAZ, jasmonate-ZIM domain; LOX, LIPOXYGENASE; MED25, Mediator subunit 25; MTB, MYC2-TARGETED BHLH; NINJA, novel interactor of JAZ; TPL, TOPLESS.