Preparing the Astrocyte Perivascular Endfeet Transcriptome to Investigate Astrocyte Molecular Regulations at the Brain-Vascular Interface.

Astrocytes send out long processes that are terminated by endfeet at the vascular surface and regulate vascular functions in particular through the expression of a specific molecular repertoire in perivascular endfeet. We recently proposed that local translation might sustain this structural and functional polarization. More specifically we showed that a subset of mRNAs is distributed in astrocyte endfeet and characterized this transcriptome. We also identified among these endfeet RNAs, the ones bound to ribosomes, the polysomal astrocyte endfeet mRNAs, which we called the endfeetome. Here, we describe experimental strategies to identify mRNAs and polysomes in astrocyte perivascular endfeet, which are based on the combination of gliovascular unit purification and astrocyte-specific translating ribosome affinity purification.