In the complex hierarchy of a beehive, the queen bee is the powerful matriarch who keeps the colony alive, organized and populated by laying the eggs from which larvae will hatch. The larvae later become either the new workers, which are the female bees who do all the work around the hive, or the drones, the male bees whose job it is to mate with the queen.
When a queen bee dies, the colony has to ensure that a new one takes her place. To produce a new queen bee, worker bees select the most suitable larvae and feed them a gelatinous substance referred to as ‘royal jelly’. This allows one of them to develop into the healthy, strong, and extremely fertile adult female who then becomes the new queen bee.
Researchers at Stanford University in the US studying exactly how royal jelly, which comprises of water, proteins, and sugars, is so beneficial to larvae growth, have homed in on a protein called royalactin that they believe is responsible for the impressive growth in the larvae that worker bees select to become queen bees.
The researchers also looked at its effect on one of the most promising targets of clinical research, namely mammalian stem cells. These undifferentiated cells are pluripotent, meaning they are capable of turning into any specialized cells, serving any function.
The research team also found that the DNA sequence of royalactin, is structurally similar to a protein identified with stem cell pluripotency in mammalian stem cells. Pluripotency is the ability of embryonic stem cells to transform into any specialized cell in the body.
In order to study its effects, the researchers decided to apply royalactin to embryonic stem cells, or undifferentiated cells, that they had collected from mice.
Replacing aging, damaged specialized cells with fresh ones that have grown from stem cells has, in theory, the potential to help address any number of diseases. As a result, it is important for researchers to have access to a ready supply of healthy, ‘youthful’ stem cells. But stem cells kept in the labs in their undifferentiated forms soon begin to differentiate and become unusable. To keep their pluripotency intact, researchers have had to devise complex inhibitors.
When they added royalactin to embryonic stem cells, the investigators found that it maintained their pluripotency for longer — specifically, for 20 generations — without the need to administer the usual inhibitors.
The researchers were puzzled by the result of royalactin, as mammalian stem cells do not normally produce that protein. Further research showed that a mammalian protein called NHLRC3, with a structure close to that of royalactin served a similar purpose. NHLRC3 occurs in all early animal embryos, including those of humans.
When the researchers applied this protein to mouse embryonic stem cells, they found that, like royalactin, it helped maintain their pluripotency. For this reason, the team decided to rename this protein ‘Regina’, which means ‘queen’ in Latin.
Researchers now believe that Regina is an important molecule governing pluripotency and the production of progenitor cells that give rise to the tissues of the embryo. In the future, the researchers plan to find out whether Regina can boost wound healing and cell regeneration. They are also looking into more ways of keeping stem cells ‘youthful’ in the laboratory.