Extended Data Fig. 2: Autophagic flux deficits associated with CLN3Δex7/8 but not CLN3Δex5/7/8 expression.
From: Therapeutic efficacy of antisense oligonucleotides in mouse models of CLN3 Batten disease
a, Schematic representation of measuring autophagic flux using GFP-RFP-LC3B. To compare the effects of CLN3 protein isoforms on autophagic flux we used a tandem acid-stable red and acid-labile green fluorescent protein (RFP, GFP) sensor fused to the autophagosome-associated protein, microtubule-associated protein light chain 3 beta (GFP-RFP-LC3B) in HEK-293 cells. The GFP signal is quenched in acidic condition and thereby the dual-labeled RFP-GFP-LC3B provides a means to differentiate between autophagosomes (red and green=yellow fluorescent LC3B) and acidic autolysosomes (red only) and assess the relative abundance of the vesicles during autophagy. LC3BII localizes to the membrane of the autophagosome, which fuses with lysosomes to form acidic autolysosomes. This acidic environment causes quenching of the GFP making the autolysosome appear red. The contents, including RFP-LC3B and p62 are then degraded by lysosomal enzymes. b, HEK-293 cells were transfected with CLN3 WT, CLN3Δex7/8 (Δ78), or CLN3Δex5/7/8 (Δ578) expression plasmids. After 44 h, the cells were transfected with the tandem reporter GFP-RFP-LC3 to examine autophagic flux. Cells were treated with DMSO (-) or to induce autophagy, AZD8055 for 20 h then imaged. Shown are representative confocal microcopy images of the formation of autophagosomes (yellow in overlay images) and autolysosomes (red in overlay images) as quantitated in Fig. 1d, n = 10 cells/group. Scale bar, 5 µm.
