Researchers at the University of Toronto have discovered more than 100 uniquely evolved genes in the human brain, providing insight into human cognitive abilities. This study, using single-cell analysis, contributes to the Human Cell Atlas and provides new perspectives on brain evolution and associated diseases.
The researchers discovered 139 genes that are common across primate groups, but whose expression differs greatly in the human brain.
An international team led by researchers at the University of Toronto has discovered more than 100 genes that are common in primate brains but whose evolutionary divergence only occurred in humans. These genes may be the source of our unique cognitive abilities.
Researchers led by Associate Professor Jesse Gillis from the Donnelly Center for Cellular and Biomolecular Research and the Department of Physiology at Temerty University School of Medicine found that genes are expressed differently in the human brain compared to four of our relatives, including the chimpanzee, gorilla, macaque, and marmoset.
The survey results are natural ecology and evolution, suggesting that reduced selective pressure, or resistance to loss-of-function mutations, may have enabled the gene to acquire higher levels of cognitive ability. This research is part of the Human Cell Atlas, a global effort to map every human cell to better understand health and disease.
Comparative study of primate brains
“This study not only contributes to our understanding of brain differences between humans and other primates at a cellular level, but also creates a database that can be used to further characterize genetic similarities and differences between primates. I did,” Gillis said.
A team including researchers from the Cold Spring Harbor Laboratory and the Allen Institute for Brain Science in the US created brain maps for each primate. seed It is based on single-cell analysis, a relatively new technology that allows for more specific gene sequencing than standard methods. They used the BRAIN Initiative Cell Census Network (BICCN) dataset, which was created from samples taken from the middle temporal gyrus of the brain.
Insights into cognitive evolution
In total, the researchers discovered 139 genes that are common across primate groups but are expressed very differently in the human brain. These genes exhibit a strong ability to tolerate mutations without affecting function, suggesting that they may have evolved under more relaxed selective pressures.
“Genes that diverge within humans must endure change,” says Hamsini Suresh, lead author of the study and a researcher at the Donnelly Center. “This appears to be a resistance to loss-of-function mutations, enabling rapid evolutionary changes in the human brain.”
Our advanced cognitive functions may be the result of human brain cells adaptively evolving into a number of less threatening mutations over time. It is also noteworthy that about a quarter of the human divergent genes identified in this study are associated with various brain diseases.
Brain cell types and gene expression
The diverse genes the researchers identified are present in 57 types of brain cells, grouped by inhibitory neurons, excitatory neurons, and non-neurons. A quarter of the genes were differentially expressed only within nerve cells, also known as gray matter, and half were differentially expressed only within glial cells, which are white matter.
The gray matter of the brain is made up of neurons, while the white matter is made up of other types of cells, such as those responsible for blood vessel structures and immune function.
Expanding the human cell atlas
This research is part of BICCN’s efforts to identify and catalog the diverse cell types in the brains of humans and other species. In 2021, the consortium published in Nature a comprehensive survey of cell types in the primary motor cortex of mice, monkeys, and humans. This effort is to shed light on the evolution of the brain by studying neurotransmission and communication at the highest resolution.
Evolution and disease research
“There are approximately 570,000 cells in the Interprimate Single Cell Atlas of the Middle Temporal Gyrus,” Suresh said. “Defining a catalog of shared cell types in this region of the brain provides a framework for investigating the conservation and divergence of cellular architecture across primate evolution.” , we can study evolution and disease in a more targeted way.”
Reference: “Comparative analysis of single-cell transcriptomes in primate brains reveals human-specific regulatory evolution” Hamsini Suresh, Megan Crow, Nikolas Jorstad, Rebecca Hodge, Ed Lein, Alexander Dobin, Trygve Bakken , by Jesse Gillis, September 4, 2023, natural ecology and evolution.
DOI: 10.1038/s41559-023-02186-7
This research was supported by the U.S. National Institutes of Health U.S. National Research Alliance on Schizophrenia and Depression.
Source: scitechdaily.com
