New transgenic mouse lines for selectively targeting astrocytes and for studying calcium signals in astrocyte processes in situ and in vivo

Summary

Astrocytes exist throughout the nervous system and are proposed to affect neural circuits and behavior. However, studying astrocytes has proven difficult because of the lack of tools permitting astrocyte selective genetic manipulations. Here, we report the generation of Aldh1l1-Cre/ERT2 transgenic mice to selectively target astrocytes in vivo. We characterised Aldh1l1-Cre/ERT2 mice using imaging, immunohistochemistry, AAV-FLEX-GFP microinjections and crosses to RiboTag, Ai95 and new Cre-dependent membrane tethered Lck-GCaMP6f knock-in mice that we also generated. Two-to-three weeks after tamoxifen induction, Aldh1l1-Cre/ERT2 selectively targeted essentially all adult (P80) brain astrocytes with no detectable neuronal contamination, resulting in expression of cytosolic and Lck-GCaMP6f and permitting subcellular astrocyte calcium imaging during startle responses in vivo. Crosses with RiboTag mice allowed sequencing of actively translated mRNAs and determination of the adult cortical astrocyte transcriptome. Thus, we provide well characterised, easy-to-use resources with which to selectively study astrocytes in situ and in vivo in multiple experimental scenarios.

ETOC/“In brief”

The Khakh laboratory developed and characterized new optical and genetic reagents to explore astrocyte functions in neural circuits. The approaches permit inducible genetic targeting of astrocytes in vivo and the selective monitoring of calcium signals in astrocyte processes.