Table 2 Factors that regulate PTTH expression or release in Drosophila
PTTH-influencing factorComments
Allatostatin A (AstA)Released by AstA neurons presynaptic to PTTHn and insulin-producing cells, and promotes PTTH release via AstA-R1; Deveci et al. (2019); commentary in Pan and O’Connor (2019).
Amino acidsGlial expression of the amino acid transporter Sobremesa (Sbm; “upon the table,” the Spanish tradition of relaxation after a heavy meal) is required for proper PTTH expression; Galagovsky et al. (2018).
Corazonin (Crz)During mid-L3, nutrition-mediating octopaminergic input to Corazonin-releasing cells presynaptic to the PTTHn induces Crz release, PTTH release, and basal ecdysone synthesis, limiting larval growth but not affecting timing; Imura et al. (2020).
DILP8Growing discs release DILP8, which acts via growth-coordinating Lgr3-expressing neurons presynaptic to PTTHn; Colombani et al. (2015); Garelli et al. (2015); Vallejo et al. (2015).
EcdysoneEcdysone promotes Ptth expression in a feedback loop contributing to the metamorphosis-triggering surge of PTTH and ecdysone; Christensen et al. (2020).
Juvenile hormone (JH)Appears to be unimportant for PTTH signaling in the fly; Mirth et al. (2014); although not in Manduca; Nijhout and Williams (1974). However, reporters of JH receptor expression are active in PTTH cells; Baumann et al. (2017).
Photoperiod/sNPFPhotoperiod affects PTTH; Truman (1972). Projections of clock neurons expressing PDF and sNPF overlap with those of the PTTHn in larval and pharate-adult brains; McBrayer et al. (2007); Selcho et al. (2017). Clock output sNPF from these neurons acts on PTTHn via sNPF-R; Selcho et al. (2017).
RetinoidsRetinoids are released by damaged discs and inhibit Ptth expression Halme et al. (2010).