General discussion I

摘要

Ono: I'd like to begin this general discussion by asking a question about MITF. I understand that MITF is extremely important for transcription of the PGD2 syn-thase gene. How is the RasGRP4 signalling moving through MITF? Is it inducing MITF or is it modifying it such that MITF-dependent genes are activated? Stevens: It is now apparent that MITF is regulated in a complex manner. At least five MITF isoforms have been identified in the body that are the result of differential splicing of the MITF precursor transcript (Takemoto et al 2002). Complicating the situation is the fact that MITF's activity can be altered if this transcription factor is post-translationally modified by SUMO (Miller et al 2005) or phosphate (Sonnenblick et al 2004). RasGRP4 and its downstream factors probably induce the phosphorylation of cytosolic MITF which enables the transcription factor to dissociate from its inhibitors).