Project description:Epitranscriptomic modifications can impact behavior. Here, we used Drosophila melanogaster to study N6-methyladenosine (m6A), the most abundant modification of mRNA. Proteomic and functional analyses confirm its nuclear (Ythdc1) and cytoplasmic (Ythdf) YTH domain proteins as major m6A binders. Assays of short term memory in m6A mutants reveal neural-autonomous requirements of m6A writers working via Ythdf, but not Ythdc1. Furthermore, m6A/Ythdf operate specifically via the mushroom body, the center for associative learning. We map m6A from wild-type and Mettl3 mutant heads, allowing robust discrimination of Mettl3-dependent m6A sites that are highly enriched in 5' UTRs. Genomic analyses indicate that Drosophila m6A is preferentially deposited on genes with low translational efficiency and that m6A does not affect RNA stability. Nevertheless, functional tests indicate a role for m6A/Ythdf in translational activation. Altogether, our molecular genetic analyses and tissue-specific m6A maps reveal selective behavioral and regulatory defects for the Drosophila Mettl3/Ythdf pathway.
Project description: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 m6A, the most abundant internal modification of mRNA. Here, we report proteomic and functional analyses of fly m6A-binding proteins, confirming nuclear (YTHDC) and cytoplasmic (YTHDF) YTH domain proteins as the major m6A binders. Since all core m6A pathway mutants are viable, we assessed in vivo requirements of the m6A pathway in cognitive processes. Assays of short term memory revealed an age-dependent requirement of m6A writers working via YTHDF, but not YTHDC, comprising the first phenotypes assigned to Drosophila mutants of the cytoplasmic m6A 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 m6A from wild-type and mettl3 null mutant heads, allowing robust discrimination of Mettl3-dependent m6A sites. In contrast to mammalian m6A, which is predominant in 3' UTRs, Drosophila m6A is highly enriched in 5' UTRs and occurs in an adenosine-rich context. Genomic analyses demonstrate that Drosophila m6A does not directionally affect RNA stability, but is preferentially deposited on genes with low translational efficiency. However, functional tests indicate a role for m6A in translational activation, since we observe reduced nascent protein synthesis in mettl3-KO cells. Finally, we show that ectopic YTHDF can increase m6A target reporter output in an m6A-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 m6A maps in this model organism and reveal selective behavioral and translational defects for m6A/YTHDF mutants.
Project description:During production of the original article [1], there was a technical error that resulted in author corrections not being rendered in the PDF version of the article.
Project description:High-throughput experiments are becoming increasingly common, and scientists must balance hypothesis-driven experiments with genome-wide data acquisition. We sought to predict novel genes involved in Drosophila learning and long-term memory from existing public high-throughput data. We performed an analysis using PILGRM, which analyzes public gene expression compendia using machine learning. We evaluated the top prediction alongside genes involved in learning and memory in IMP, an interface for functional relationship networks. We identified Grunge/Atrophin (Gug/Atro), a transcriptional repressor, histone deacetylase, as our top candidate. We find, through multiple, distinct assays, that Gug has an active role as a modulator of memory retention in the fly and its function is required in the adult mushroom body. Depletion of Gug specifically in neurons of the adult mushroom body, after cell division and neuronal development is complete, suggests that Gug function is important for memory retention through regulation of neuronal activity, and not by altering neurodevelopment. Our study provides a previously uncharacterized role for Gug as a possible regulator of neuronal plasticity at the interface of memory retention and memory extinction.
Project description:In the version of this article originally published, the reference citations in the Methods section were misnumbered. This has now been corrected in the HTML and PDF versions of the paper.