RYR2 depletion triggers unfolded protein responses. (A) GSEA of the most up-regulated hallmark gene sets upon RYR2 depletion. (B) A diagram of ER stress pathways and key regulatory genes. (C) Heatmap of the transcription profiles of key ER stress genes upon RYR2 depletion. (D) Sashimi plot of the cryptic splice site in Xbp1 transcripts as viewed by the Integrative Genome Viewer (left). The number of Xbp1s-specific exon junction reads in the RNA-Seq data was plotted (right). Seven biological replicates were analyzed. (E) Reverse-transcription PCR analysis of Xbp1 splicing variants (top). Real-time quantitative PCR analysis of spliced Xbp1 using isoform-specific primers (bottom). In (D) and (E), ***P < 0.001 by the Mann–Whitney U test. (F) Western blot analysis of ER stress markers in P10 Ctrl and RYR2-depleted ventricles that were treated with high-dose AAV. (G) Quantitative analysis of the western blot results about ATF6N, XBP1S, and ATF4. Three biological replicates were analyzed.