Researchers identify DNA switch controlling primate brain cell production

New genetic instructions for brain growth

Researchers from National Yang Ming Chiao Tung University and Academia Sinica discovered that evolution modifies DNA instructions instead of generating new genes. The study focuses on basal radial glia cells which are abundant in primate brains but rare in mice. These specialized cells divide repeatedly to expand the population needed for the cerebral cortex outer layer. Professor Pei-Shan Hou from NYCU explained that the gene itself exists in both humans and mice without difference. The critical variation lies in the operating instructions controlling how the gene functions during development.

Regulatory region acts as genetic switch

The researchers studied the DACH1 gene shared by humans monkeys and mice to understand these developmental differences. Researchers found that a tiny DNA regulatory region functions as a genetic switch to help regulate DACH1 activity levels. One feature of this region is shared among primates but differs significantly in non-primate vertebrates. In order to assess significance, researchers utilized stem cells to cultivate miniature three-dimensional replicas of the evolving cerebral cortex. Known as cortical organoids these structures reproduce early brain development features allowing study of difficult processes.

Removing DNA region reduces cell markers

After researchers excised the regulatory DNA region, the organoids generated fewer cells displaying a key basal radial glia marker. Other important neural progenitor populations remained largely unchanged during this specific experimental manipulation. The team then introduced the human version of the regulatory region into mouse models to observe effects. This process demonstrates how evolution opens new developmental possibilities without necessarily creating entirely new genes in the genome.