Even fifteen years after the human genome has been sequenced, researchers are still unsure about much of the data. Frank Jacobs of the University of Amsterdam was comparing gene expression patterns in cortical organoids grown from embryonic stem cells of humans and rhesus monkeys.
A set of three nearly identical genes found only in humans appear to play a critical role in the development of our large brains, according to a study led by researchers at the University of California, Santa Cruz.
This is a family of genes that goes back hundreds of millions of years in evolutionary history and is known to play important roles in embryonic development.
The genes, called NOTCH2NLA, NOTCH2NLB, and NOTCH2NLC, are a type associated with “notch signaling“, a cell signaling system so named because it was first discovered in fruit flies with notched wings. This happened in an ancient ape species that was a common ancestor of humans, chimpanzees, and gorillas. Notch proteins are involved in signaling between and within cells.
Notch signaling was already known to be important in the developing nervous system, said senior author Sofie Salama, a research scientist at UC Santa Cruz.
Salama noted that the new genes are just one of many factors that contribute to cortical development in humans. Because of where they are located in the genome, the genes may also be directly implicated in neurological disorders like ADHD, autism spectrum disorder, and schizophrenia. An international research team has published data from a group of studies, which have uncovered new genetic variants associated with the autoimmune disease, psoriasis. The results were reported across five papers published in the journal Nature Genetics.
The researchers also analyzed the genomes of three Archaic humans, two Neanderthals, and one Denisovan, finding in all of them the same three active NOTCH2NL genes that are present in modern humans. But the genetic changes behind the expansion that made us human have been elusive. Human brains are three times bigger than those of our ancestors. David Haussler‘s team at the UC Santa Cruz Genomics Institute looked at what happened when NOTCH2NL wasn’t expressed. Together, the results suggest that NOTCH2NL genes played a role in beefing up human brain size.
The mouse is the most widely used model organism to understand human genetics, biology, and diseases in the research setting. Researchers have for the first time used a gene editing technique to successfully cure a genetic condition in a mouse model. They analyzed differences in functions between mice and humans in this gene family that can not be overlooked, if scientists are to be able to interpret mouse model experiments for purposes of diagnosis and treatment of human diseases. Researchers have identified three genes involved in brain development which may have contributed to the rapid evolution of the humans from other apes roughly three million years ago.