February 22, 2012
Blood Vessel Origins Discovered
Researchers from the California and Florida campuses of The Scripps Research Institute have discovered the biological origins of the closed circulation system of vertebrates.
Closed circulation systems are complex and take generations, possibly billions of years to develop.
A recent press release notes: “During this lengthy process, new domains (parts of a protein that can evolve and function independently of each other) have been added progressively to key molecules.”
In their research, the scientists looked at a certain domain UNE-S. USE-S is part of SerRS, a tRNA synthetase specifically found in species with closed circulation systems; tRNA synthetases are enzymes that help charge tRNA with the correct amino acid to correctly translate genetic information from DNA to proteins.
The researchers found that UNES contains a specific sequence or “nuclear localization signal” that directs SerRS to the cell nucleus where it affects the expression of a key regulator of new blood vessel growth.
Xiang-Lei Yan, a Scripps Research associate professor who led the study, said “I think a lot happened during this evolutionary transition to a closed system and the appearance of this domain on this specific synthetase is one of them. Because this synthetase plays such an essential role in vascular development, it must have had a role in the transition to a closed system.”
In order to study the protein expression of UNE-S the researchers looked at the zebrafish. Shuji Kishi, an assistant professor on the Scripps Florida campus who worked on the study said, “Zebrafish offer a number of advantages for study because embryonic development is external to the mother and the embryos are transparent, making them an ideal model for developmental biology.”
The research team studied SerRS mutants, who had abnormal blood vessel development and defective blood circulation. The experiments included crystal structure, biochemical analysis, and cell biology experiments. The research showed the SerRS mutants had their nuclear signal sequestered or hidden making it ineffective.
They were able to reverse the hidden signal by creating a second mutation, restoring normal blood vessel and circulation development.
The research is published in the journal Nature Communications.
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