Extended Data Fig. 9: RABV-tracing of SCLC cells to presynaptic neurons.
From: Functional synapses between neurons and small cell lung cancer
a) RABV-GFP-based tracing of neurons monosynaptically connected to DMS273 SCLC cells expressing DsRed. Right panels show enlarged views of the boxed area containing double-positive starter SCLC cells (arrowheads). b) 3D reconstruction of double-positive starter cells in a cluster of DsRed-expressing SCLC cells (COR-L88) following RABV-GFP-based tracing. c) Magnification of the panel boxed in b, showing the profuse expression of VGluT1-positive puncta in GFP-positive neuronal fibers (yellow arrowheads) contacting starter SCLC cells. d) Time-lapse of RABV-traced neurons in neuron-SCLC co-cultures over 48 h. Selected frames at the indicated time points show the initial presence of starter cancer cells (double-positive for the retrovirally-encoded DsRed and the RABV-encoded GFP, yellow arrowheads), which proliferate over time, and the emergence of GFP+ neurons at 48 h (white arrowheads). e) Example of RABV-GFP-based tracing of morphologically identified inhibitory GABAergic neurons located in the stratum oriens (SO) and pyramidale (SP) of CA1, following transplantation of G-TVA-expressing murine SCLC cells (dashed area). Right panels show zooms of the boxed areas depicting identified GFP+ neurons (1) and starter SCLC cell (2), contacted by varicosities of a passing axon (arrowheads). SR, stratum radiatum. f) Example of RABV-GFP-based tracing following transplantation of TVA-only-expressing murine SCLC cells (dashed area), showing the virtual absence of GFP-positive presynaptic neurons. Right panels show zooms of the boxed area depicting an identified DsRed/GFP double-positive SCLC cell (arrowhead).
