Since the COVID-19 pandemic began, scientists began to investigate its characteristics and behavior. They soon discovered that the SARS-CoV-2, virus that causes disease, binds through the spike protein (S) to the ACE2 receiver, allowing it to adhere to human cells and infect them. Now, they have discovered a second key that allows the virus to enter our body: the membrane protein AXL.
During their research, a group of Chinese scientists confirmed what some studies say, that ACE2 receptor activity in the respiratory tract is extremely low. So the experts thought of the existence of a coreceptor that could be more active and therefore more beneficial for the virus. This is how they found the protein AXL, what has been studied in relation to lung cancer and it is one of 58 types that has a family of receptors called tyrosine kinases.
“We found that the UFO receptor tyrosine protein kinase (AXL) specifically interacts with the N-terminal domain of SARS-CoV-2 S”, Specify the authors of the study, published in the journal Cell Research. “AXL is widely expressed in almost all human organs. In particular, in cells and lung epithelial tissue and human bronchial, the expression of AXL is much higher than that of ACE2 ”, they add.
Just as efficient overexpression
During the experiments, in which 22 different proteins, the scientists observed that the overexpression of AXL is as efficient for COVID-19 penetration as ACE2 overexpression, while “Elimination of AXL significantly reduces SARS-CoV-2 infection” in lung cells. “Soluble human recombinant AXL blocks SARS-CoV-2 infection in cells expressing high levels of AXL,” they explain.
On the other hand, they also found that AXL interacts with protein S in a different area than the ACE2 receptor does, something that could explain why many have been identified neutralizing human antibodies that bind to protein S but not to its binding site with the ACE2 receptor.
By way of conclusion, the scientists say that their findings “suggest that AXL is a novel candidate receptor for SARS-CoV-2 that may play a role. big role in the promotion of viral infection of the respiratory system human and indicates that it is a potential target for future clinical intervention strategies”.