The Arabidopsis Hippo/SIK1 negatively regulates Jasmonate signaling

Everything that has a beginning has an end. For animals, growth stops when organs reach their target size. The Hippo signaling pathway is an evolutionarily conserved pathway that restricts organ size by inhibiting cell proliferation and promoting cell death. Hence this pathway is vital in both organ regeneration and cancer development, and timing is essential. In plants, when an insect bites a leaf, the plant hormone jasmonates (JA) act right after wounding to terminate plant growth and to initiate defense. When JA signaling is on, amino acid-conjugated JA binds to its receptor, the LRR and RING domain protein COI1, which also acts as a F-box protein in SCFCOI1 ubiquitin ligase that labels the transcription repressors, the JAZ proteins, for degradation. Then the key transcription factor in JA signaling, MYC2, is free to promote JA-responsive gene expression. How MYC2 activity and JA signaling is terminated is not fully understood. We found out that the Arabidopsis Hippo ortholog, SIK1, acts on MYC2 to repress JA signaling. SIK1 mRNA and protein levels themselves are induced by JA for a timely ending of JA signaling. In this RNA-seq dataset, we found out that sik1 has reduced JA signaling, and that sik1 myc2 is similar to myc2 in its transcriptome, validating the genetic interactions between SIK1 and MYC2.