Rapid Changes in the Translatome during the Conversion of Growth Cones to Synaptic Terminals

• Tandemly tagged ribosome affinity purification of RNA from neuronal cell types
• Changes in mRNA associated with ribosomes during presynaptic differentiation
• Dramatic changes in cell surface protein expression with presynaptic differentiation
• Changes in 3′ UTRs in mRNAs for presynaptic proteins during development

SummaryA common step in the formation of neural circuits is the conversion of growth cones to presynaptic terminals. Characterizing patterns of global gene expression during this process is problematic due to the cellular diversity of the brain and the complex temporal dynamics of development. Here, we take advantage of the synchronous conversion of Drosophila photoreceptor growth cones into presynaptic terminals to explore global changes in gene expression during presynaptic differentiation. Using a tandemly tagged ribosome trap (T-TRAP) and RNA sequencing (RNA-seq) at multiple developmental times, we observed dramatic changes in coding and non-coding RNAs with presynaptic differentiation. Marked changes in the mRNA encoding transmembrane and secreted proteins occurred preferentially. The 3′ UTRs of transcripts encoding synaptic proteins were preferentially lengthened, and these extended UTRs were preferentially enriched for sites recognized by RNA binding proteins. These data provide a rich resource for uncovering the regulatory logic underlying presynaptic differentiation.

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