A neural m⁶A/YTHDF pathway is required for learning and memory inDrosophila

Abstract

The roles of epitranscriptomic modifications in mRNA regulation have recently received substantial attention, with appreciation growing for their phenotypically selective impacts within the animal. We adopted Drosophila melanogaster as a model system to study m 6 A, the most abundant internal modification of mRNA. Here, we report proteomic and functional analyses of fly m 6 A-binding proteins, confirming nuclear (YTHDC) and cytoplasmic (YTHDF) YTH domain proteins as the major m 6 A binders. Since all core m 6 A pathway mutants are viable, we assessed in vivo requirements of the m 6 A pathway in cognitive processes. Assays of short term memory revealed an age-dependent requirement of m 6 A writers working via YTHDF, but not YTHDC, comprising the first phenotypes assigned to Drosophila mutants of the cytoplasmic m 6 A reader.These factors promote memory via neural-autonomous activities, and are required in the mushroom body, the center for associative learning. To inform their basis, we mapped m 6 A from wild-type and mettl3 null mutant heads, allowing robust discrimination of Mettl3-dependent m 6 A sites. In contrast to mammalian m 6 A, which is predominant in 3' UTRs, Drosophila m 6 A is highly enriched in 5' UTRs and occurs in an adenosine-rich context. Genomic analyses demonstrate that Drosophila m 6 A does not directionally affect RNA stability, but is preferentially deposited on genes with low translational efficiency. However, functional tests indicate a role for m 6 A in translational activation, since we observe reduced nascent protein synthesis in mettl3-KO cells.Finally, we show that ectopic YTHDF can increase m 6 A target reporter output in an m 6 A-binding dependent manner, and that this activity is required for in vivo neural function of YTHDF in memory. Altogether, we provide the first tissue-specific m 6 A maps in this model organism and reveal selective behavioral and translational defects for m 6 A/YTHDF mutants.

METTL3 counteracts premature aging via m6A-dependent stabilization of MIS12 mRNA

“…Combined with the functional validations showing that METTL3 overexpression alleviated cellular senescence in prematurely senescent hMSCs, we reached a conclusion that METTL3 as well as m 6 A play important roles in stem cell senescence. Consistent with our conclusion, a recent study has reported that METTL3 deficiency shortens lifespan in Drosophila ( 77 ).…”

RNA N6‐methyladenosine modification suppresses replication of rice black streaked dwarf virus and is associated with virus persistence in its insect vector

“…Among insects, the most studied m 6 A modification is in the model species D. melanogaster. In Drosophila, the orthologs of METTL3, METTL14, WTAP, and KIAA1429 are Ime4, dMettl14, Fl (2)d, and Virilizer, respectively (Kan et al, 2021).…”

“…Among insects, the most studied m 6 A modification is in the model species D. melanogaster . In Drosophila , the orthologs of METTL3, METTL14, WTAP, and KIAA1429 are Ime4, dMettl14, Fl (2)d, and Virilizer, respectively (Kan et al, 2021 ). The decrease of Fl(2)d in Drosophila reduces the interaction between Ime4 and dMettl14 (Lence et al, 2016 ), similar to the function of WTAP in mammals.…”