Fig. 4.

Activin signaling promotes transcription of the InR/TOR pathway components Pdk1 and Akt1. (A) Heat map shows the effects of Smad2 loss and temporal overexpression of babo^CA on the transcript levels of InR/TOR pathway components. Although most of the components are not affected, the expression of Pdk1 and Akt1, highlighted by a red rectangle in the heat map, are downregulated by Smad2 mutation and upregulated by temporal expression of babo^CA. (B) Verification of the RNA-seq results by qPCR. (C) Consistent with the RNA-seq and qPCR results, the total protein level of AKT1 is decreased in babo and Smad2 mutants. (D) Overexpression of Pdk1 in Smad2 muscle restores the increased pAKT1 level towards that of wild type. (E) Expression of Pdk1RNAi in the skeletal muscle produces a similar phenotype in pAKT1 level as loss of Activin signaling, whereas Pdk1 overexpression suppresses AKT1 phosphorylation. (F) A heteroallelic combination of Pdk1 mutations causes hyperphosphorylation of AKT1. Values are mean±s.e.m. *P<0.05, **P<0.01 and ***P<0.001 from one-way ANOVA followed by Dunnett's test in which each genotype was compared with wt (B-D,F) or Mef2-Gal4/+ control (E). Additionally, unpaired t-tests were performed in D and F as indicated by lines; ^###P<0.001.