Expression data from skeletal muscles of flies with muscle-specific overexpression of Foxo or Mnt. Drosophila melanogaster

Skeletal muscle senescence influences whole organism aging, yet little is known on the relay of pro-longevity signals from muscles to other tissues. We performed an RNAi screen in Drosophila for muscle-released cytokines (?myokines?) regulating lifespan and identified Myoglianin, the homolog of human Myostatin. Myoglianin is induced in skeletal muscles by the transcription factor Mnt and together they constitute an inter-organ signaling module that regulates lifespan, age-related muscle dysfunction, and protein synthesis across aging tissues. Both Mnt and Myoglianin activate already in young age the protective decline in protein synthesis that is typical of old age, while knock-down of Myoglianin impairs this process. Mechanistically, Mnt decreases the expression of nucleolar components in muscles while also decreasing nucleolar size in distant tissues via Myostatin/p38 MAPK signaling. Our results highlight a myokine-dependent inter-organ longevity pathway that coordinates nucleolar function and protein synthesis across aging tissues. Affymetrix microarrays were used to evaluate genome-wide expression in skeletal muscles of flies with muscle-specific overexpression of FOXO or Mnt (Affymetrix Drosophila Genome 2.0 Array). This design allowed us to identify genes and pathways induced by overexpression of FOXO and/or Mnt, and enabled us to address the degree to which FOXO-induced pathways were independent of those induced by Mnt. Overall design: Three independent biological replicates from each of three groups (control, UAS-Foxo and UAS-Mnt)