Comparison of JH signaling in insects and crustaceans

• JH signaling in insects and crustaceans plays similar regulatory roles.
• Methyl farnesoate is an innate JH of crustaceans.
• Daphnia ‘JH receptor’ Met responds to methyl farnesoate.
• JH signaling seems to be widely conserved among the Arthropoda.

Physiological importance of sesquiterpenoids such as the juvenile hormone (JH) has been recognized in both insects and crustaceans. Yet, little is known about when and how these two closely related arthropod groups acquired the JH signaling system. Methyl farnesoate (MF), a natural precursor of insect JH, has been identified as an innate JH of crustaceans. However, the reception and molecular signaling downstream of MF in crustaceans is much less explored than JH signaling is in insects, where the Methoprene-tolerant (Met) protein has been characterized as a JH receptor. A recent study has shown that Daphnia Met responds to MF in a way insect Met responds to JH, suggesting that JH reception is conserved between insects and crustaceans. To understand the origin and evolution of JH signaling, further studies, extended to more ancestral arthropods, are needed.