The secret mechanisms that make a cell in a certain animal species significantly more complex than a similar cell in a different animal is apparently due to proteins and their ability to control what happens in the inner nucleus of the cell.
It has come out thanks to research led by biochemist Colin Sharpe and his colleagues at the University of Portsmouth, UK, and published in PLoS One .
According to Dr. Sharpe, “almost everyone agrees that mammals, and humans in particular, are more complex than a worm or fruit fly but without really knowing why. This question leads us time intriguing. A common way to measure complexity is by counting the number of different cells in a species, but little is known about how that complexity is achieved at the genetic level. But the total number of genes in a genome is not necessarily an indicator , so we decided to look for other factors. “
Sharpe and his assistant Daniela Lopes Cardoso analyzed stacks of data from the genomes of nine animal species – humans, macaques, nematode worms, sea urchins and fruit flies , among others – and calculated the diversity of each at the genetic level. They found a small number of proteins that efficiently interacted with other proteins and with chromatin, the substance that creates the way DNA is presented in the cell nucleus.
According to Sharpe, “these proteins appeared to be excellent candidates for figuring out what underlies the enormous variety of degrees of complexity in animals . We hoped to identify genes that directly interact with DNA in the regulation of other genes , but this was not the one. case.
Instead, what happened was that we identified genes that interact with chromatin. Our results suggest that the increasing ability of certain proteins to interact with others to regulate the dynamic organization of chromatin in the nucleus is a component of animal complexity . “
This is important because biomedical scientists can better understand human diseases by studying them in animals . But at the same time, we are concerned that an animal model may be too simple to be useful when applied to humans and that the results we see in a simpler species do not correlate with what happens in more complex animals.
Understanding the inherent differences in the organization at the genetic level between animals and the limitations that this brings with it when interpreting them can help us to make a more rational selection of appropriate and effective models in biomedicine. Previous research by Sharpe and his team found three factors that influence proteins made by a single gene – the NCoR – and that were more diverse in more complex species like humans compared to simpler animals like sea urchins:
– Genetic duplication . Although there is no significant difference in the total number of genes in a genome, some specific genes are duplicated one or more times. For example, there is one NCoR gene in the sea urchin and two in humans.
– Simple genes sometimes make more than one protein . The messenger RNA that connects the gene to the protein can be spliced to generate a different range of mRNAs, each encoding a related but different protein. For example, the sea urchin gene produces only one type of RNA, whereas in humans the gene
NCoR2 produces more than 30, each with a different function.
– Most proteins are encompassed in domains with specific functions . Sharpe and his team found that the number of domains increases with NCoR from one in sea urchins to three in humans.
