FIG. 6.
ECM components generated by ESC-derived astrocytes are found in cortical astrocytes based on BAC-TRAP. (A) Astrocyte-specific genes (red) are enriched in the TRAP fraction, while neuronal-specific genes (green) are enriched in the Pre-IP samples. n = 3. (B) ECM candidate genes are enriched within the TRAP fraction compared to Pre-IP sample. Lines are 95% and 68% confidence of astrocyte-specific expression. Gray points are all genes detected in the BAC-TRAP data, red points denote genes that code for proteins detected in ECM proteomics data. (C) ECM proteins are significantly enriched in TRAP fraction compared to the Pre-IP fraction. Paired t-test, P = 5.66 × 10−9. (D) Comparison of identified proteins with the proteomics and BAC-TRAP data. Proteins were considered astrocyte expressed if there was 95% confidence that the mRNA was enriched within the TRAP fraction compared to the Pre-IP fraction. The ECM proteins identified in proteomics were enriched for protein expression in astrocytes based on BAC-TRAP at a significantly higher level than expected by chance. Fisher's exact test, P = 2. × 10−7. TRAP, translating ribosome affinity purification. Color images available online at www.liebertpub.com/scd