FLARIM v2.0, an improved method to quantify transcript-ribosome interactions in vivo in the adult Drosophila brain

Abstract

Neural injury triggers striking immune reactions from glial cells, including significant transcriptional and morphological changes, but it is unclear how these events are coordinated to mount an effective immune response. Here, we present a new variant of the Fluorescence assay to detect ribosome interactions with mRNA (FLARIM), which we term FLARIM v2.0, to visualize single immune gene transcripts and association with ribosomes in glia responding to neurodegeneration. Specifically, using an in vivo axotomy assay in Drosophila, we show that matrix metalloproteinase-1 (Mmp-1) mRNAs and associated ribosomes are detected in distal processes of reactive glia where they are actively engulfing degenerating axonal material, suggesting that local translation is an important component of the glial immune response to axotomy. This work also validates our enhanced FLARIM assay as a promising tool to investigate mechanisms of mRNA transport and translation in a wide range of in vitro and in vivo paradigms.