The MGC8902 gene is the main cause of human braininess?
The reason for the difference between the brains of humans and primates has been found
Copper news based on EurekAlert materials! – Evolutionary increase in size of the human brain explainedA group of scientists from a number of scientific centers in the USA and Italy managed, as they believe, to find the key genetic basis for such a sharp difference in the human brain from the brains of other primates and mammals in size and cognitive functions.
These features of the human brain are associated, as shown by a study published on August 16 in the American Journal of Human Genetics (Dumas et al., DUF1220-Domain Copy Number Implicated in Human Brain-Size Pathology and Evolution), with the number of copies of DUF1220 protein domains expressed in each protein-coding region of the human genome.
DUF1220 (Domain of Unknown Function – "domain with unknown function") is a protein domain (an autonomous element of the protein structure in its functions) encoded by the MGC8902 gene (the so–called "unknown gene"), distributed in the human genome much more frequently than in other mammals. The human genome contains 212 copies of the MGC8902 gene, the chimpanzee – 37 copies, the mouse and rat genomes – one copy each.
The function of the MGC8902 gene is not completely clear, however, in 2006 a group of scientists from the University of Colorado, whose work (Popesco et al., Human Lineage–Specific Amplification, Selection, and Neuronal Expression of DUF1220 Domains) was published in the journal Science, hypothesized the association of this gene and its expression products with cognitive brain functions. Their work indicates that the greatest expression of DUF1220 is noted in the bodies and dendrites of neurons of the brain regions most associated with the processes of cognition.
The authors of the study in question established a strict correlation between brain size and the number of copies of DUF1220 encoded in the genome. In humans, this figure exceeds 270, which is more than twice the level of chimpanzees – 125. In gorillas, this number is 99, in marmoset monkeys - 30, and mice - one.
The study compared not only the genomes of humans and other representatives of primates, but also the DNA sequences of individuals suffering from micro- and macrocephaly with people from the control group. It turned out that in microcephals suffering from brain underdevelopment, the number of copies of DUF1220 is significantly lower than normal, while in macrocephals whose brain is too large, this indicator exceeds the norm. In addition, in healthy people, there was a direct relationship between the amount of DUF1220 and the volume of gray matter in the brain.
According to James Sikela from the University of Colorado, who led the group, the results of the study can help in the diagnosis of diseases related to brain size, and in a broader sense gives an opportunity to take a fresh look at the process of evolution of the human brain.
Portal "Eternal youth" http://vechnayamolodost.ru20.08.2012