SUMMARY
The cerebral cortex has expanded in size and complexity in primates, yet the underlying molecular mechanisms are obscure. We generated cortical organoids from human, chimpanzee, orangutan, and rhesus pluripotent stem cells and sequenced their transcriptomes at weekly time points for comparative analysis. We used transcript structure and expression conservation to discover thousands of expressed long non-coding RNAs (lncRNAs). Of 2,975 human, multi-exonic lncRNAs, 2,143 were structurally conserved to chimpanzee, 1,731 to orangutan, and 1,290 to rhesus. 386 human lncRNAs were transiently expressed (TrEx) and a similar expression pattern was often observed in great apes (46%) and rhesus (31%). Many TrEx lncRNAs were associated with neuroepithelium, radial glia, or Cajal-Retzius cells by single cell RNA-sequencing. 3/8 tested by ectopic expression showed ≥2-fold effects on neural genes. This rich resource of primate expression data in early cortical development provides a framework for identifying new, potentially functional lncRNAs.
