Fig 2: CRTC1 proxisome in silenced neurons:A) Volcano plot of cytoplasmic CRTC1 proximal proteins. Proteins enriched in CRTC1-APEX2 over untransduced (Log2 iFold Change > 2 and iP-Value <0.05) are depicted in red, depleted proteins in blue and proteins that were not enriched in grey. B) Pie chart of subcellular localization of CRTC1 proximal proteins detected in silenced neurons. Subcellular localization was obtained from COMPARTMENTS Annotation and simplified into shown categories. C) Gene ontology enrichment analysis for Biological Process of cytoplasmic CRTC1 proximal proteins dobtained from EnrichR, with the size of each marker indicating the number of genes in proxisome for that category and shading indicating adjusted p-value. D) Number of cytoplasmic CRTC1-proximal proteins in functional categories obtained from STRING database. E) Known protein interactions of cytoplasmic CRTC1 proximal proteins obtained from the STRING database, with marker size for each protein indicating enrichment in CRTC1 proxisome. F) Heatmaps of CRTC1 proxisomal proteins showing Log2 of imputed Fold Change and negative Log10 of imputed P-values.

Fig 3: Activity-dependent proximity of CRTC1 and CREB1 to MEF2C and RFX3 in neurons.A) Representative images of PLA of CREB1 with CRTC1, MEF2C or RFX3 in silenced (TTX) and stimulated (BIC) neurons (left). Quantification of PLA signal (right). B) Images of PLA of CRTC1 with MEF2C or RFX3 in silenced (TTX) or stimulated (BIC) neurons (left). Quantification of PLA signal (right). Data were obtained from 3-4 different neuronal cultures. Means of data were compared with a pairwise Wilcoxon test (ns = not significant; p< 0.5 = **; p<0.1 = ***; p<0.01 = ****). Numbers in graphs indicate the number of analyzed cells. Scale bar represents 10 μm.

Fig 4: CRTC1 proxisome in stimulated neurons:A) Volcano plots of nuclear CRTC1 proximal proteins. Proteins enriched in CRTC1-APEX2 over untransduced (Log2 iFold Change > 2 and iP-Value <0.05) are depicted in red, depleted proteins in blue and proteins that were not enriched in grey. B) Pie chart of subcellular localization of CRTC1 proximal proteins detected in stimulated neurons. Subcellular localization was obtained from COMPARTMENTS Annotation and simplified into shown categories. C) Gene ontology enrichment analysis for Biological Process of CRTC1 proximal proteins detected in stimulated neurons obtained from EnrichR. D) Number of proteins in functional categories obtained from STRING database. E) Known protein interactions of CRTC1 proximal proteins detected in stimulated neurons obtained from the STRING database. F) Heatmaps of CRTC1 proxisomal proteins showing Log2 of imputed Fold Change and negative Log10 of imputed P-values.

Fig 5: CRTC1 binds to regions enriched in motifs for MEF2C and RFX3 in hippocampus:A) Images of CRTC1 staining in the hippocampal CA1 region in control (ACSF) or stimulated (DHPG) conditions. B) Browser tracks of ChIP-seq signal from hippocampal CA1 at the cFos locus of CRTC1 with ACSF or DHPG. ChIP-seq signal for H3K4me3 and H3K27ac from the CA1 region of naïve animals were obtained from study GSE74971. C) Genomic annotation of CRTC1 consensus peaks from hippocampal CA1. D) Heatmaps of average normalized ChIP-seq signals for CRTC1 from CA1 treated with ACSF or DHPG. E) Motif enrichment for CREB1, MEF2C and RFX3 in CA1 CRTC1 binding regions.