Tale of cAMP as a second messenger in auxin signaling and beyond

Abstract

SummaryThe 3′,5′‐cyclic adenosine monophosphate (cAMP) is a versatile second messenger in many mammalian signaling pathways. However, its role in plants remains not well‐recognized. Recent discovery of adenylate cyclase (AC) activity for transport inhibitor response 1/auxin‐signaling F‐box proteins (TIR1/AFB) auxin receptors and the demonstration of its importance for canonical auxin signaling put plant cAMP research back into spotlight. This insight briefly summarizes the well‐established cAMP signaling pathways in mammalian cells and describes the turbulent and controversial history of plant cAMP research highlighting the major progress and the unresolved points. We also briefly review the current paradigm of auxin signaling to provide a background for the discussion on the AC activity of TIR1/AFB auxin receptors and its potential role in transcriptional auxin signaling as well as impact of these discoveries on plant cAMP research in general.

Debora Gasperini

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“… 93 The auxin receptors TRANSPORT INHIBITOR RESPONSE 1/AUXIN SIGNALING F-BOX (TIR1/AFB) are F-box proteins that determine the substrate specificity of the Skp1-cullin 1-F-box (SCF) type E3 ubiquitin ligase complex. 94 , 95 Binding of IAA results in an increased interaction with the auxin/indole-3-acetic acid (Aux/IAA) co-receptors. 94 This interaction of Aux/IAA and TIR1/AFB leads to the ubiquitination and degradation of Aux/IAA.…”

“… 94 , 95 Binding of IAA results in an increased interaction with the auxin/indole-3-acetic acid (Aux/IAA) co-receptors. 94 This interaction of Aux/IAA and TIR1/AFB leads to the ubiquitination and degradation of Aux/IAA. 94 Aux/IAA act as repressor of the auxin response factors (ARF).…”

“… 94 This interaction of Aux/IAA and TIR1/AFB leads to the ubiquitination and degradation of Aux/IAA. 94 Aux/IAA act as repressor of the auxin response factors (ARF). 94 IAA-mediated degradation of Aux/IAA therefore promotes the ARF activity and results in a transcriptional reprogramming.…”

“… 94 Aux/IAA act as repressor of the auxin response factors (ARF). 94 IAA-mediated degradation of Aux/IAA therefore promotes the ARF activity and results in a transcriptional reprogramming. 94 Apart from this, it has been shown that TIR1/AFB also contain an adenylate cyclase domain and its activity is increased by binding of IAA to TIR1/AFB.…”