Gbx2 Identifies Two Amacrine Cell Subtypes with Distinct Molecular, Morphological, and Physiological Properties

Abstract

Summary: Our understanding of nervous system function is limited by our ability to identify and manipulate neuronal subtypes within intact circuits. We show that the Gbx2CreERT2-IRES-EGFP mouse line labels two amacrine cell (AC) subtypes in the mouse retina that have distinct morphological, physiological, and molecular properties. Using a combination of RNA-seq, genetic labeling, and patch clamp recordings, we show that one subtype is GABAergic that receives excitatory input from On bipolar cells. The other population is a non-GABAergic, non-glycinergic (nGnG) AC subtype that lacks the expression of standard neurotransmitter markers. Gbx2+ nGnG ACs have smaller, asymmetric dendritic arbors that receive excitatory input from both On and Off bipolar cells. Gbx2+ nGnG ACs also exhibit spatially restricted tracer coupling to bipolar cells (BCs) through gap junctions. This study identifies a genetic tool for investigating the two distinct AC subtypes, and it provides a model for studying synaptic communication and visual circuit function.

Keywords

• electrical synapses
• vision
• neural circuit
• neuronal identity
• amacrine
• retina