Because humans and chimpanzees share the same DNA to a large extent, researchers have long used genetic regulatory changes to study the evolutionary differences between the two. However, scientists from the University of Chicago have now discovered that mRNA expression levels, which have long been regarded as differential markers of gene regulation, often do not reflect differences in protein expression and biological functions between humans and chimpanzees. This work was published in the journal Science. Dr. Yoav Gilad, a professor of human genetics at the University of Chicago, said: "We thought we already knew how to recognize the difference in mRNA expression levels between humans and chimpanzees, and they are reliable candidate indicators with functional significance. But now we see this Of mRNA patterns have not been converted to protein levels, which means that they are unlikely to affect functional phenotypic differences. " In order to achieve gene expression, DNA must first be transcribed into messenger RNA (mRNA), and then mRNA is encoded to produce protein, which is the basic building block of biology and the engine that drives cell functions. Although humans and chimpanzees share highly similar genomes, previous research has shown that the evolution of the two species at the level of mRNA expression has made a big difference. Many of these differences are believed to indicate regions of evolutionary divergence, thus pointing to genes that are critical for human-specific traits. To verify this claim, Gilad, Jonathan Pritchard, currently at Stanford University, and their research team used high-resolution mass spectrometry to compare the expression levels of thousands of proteins in human and chimpanzee cell lines with the corresponding mRNA expression data. Compare. The research team found that there are differences in the mRNA expression levels of 815 genes, while there are differences in the protein levels of only 571 genes. Overall, they found that 266 genes with mRNA differences did not produce changes in protein levels. When they compared the rhesus macaque cell line with chimpanzee and human cell lines, they also saw similar results, confirming this trend. "Some of the mRNA control patterns used to be regarded as evidence of natural selection of important human genes, but now they can no longer think so," Gilad said. The new study raises the question: If differences in mRNA expression levels do not necessarily lead to protein differences, what are the reasons for such differences between species? Although further research is needed, Gilad believes that this study shows protein expression Compared with mRNA level, the level of evolution is more restricted by an unknown compensation or buffer mechanism. At present, studies that use mRNA expression levels as a measure of the importance of gene function need to be reassessed, and are not just evolutionary studies. "We gained some understanding of complex diseases by studying mRNA transcription, but there are still a lot of holes in our knowledge. Perhaps some of them are caused by this inconsistency," Gilad said.
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