Prions: What do we know about squirrels that kill
Protein - the main building material of the body and a constant component of a healthy diet. Although squirrels have always worried researchers, today the attention of the latter has shifted to a special species, prions. On the Internet as they just do not call: "ideal killer," "key to immortality," and even "zombie molecule." The scientific community puzzles over how to use proteins that can rapidly and inevitably destroy the brain, for the benefit of mankind. We decided to figure out what prions are, and asked the experts what killer proteins could potentially be useful for humans.
Why talk about them
Prions began to be studied, because they were the cause of rare, but very dangerous diseases of humans and animals. Among them is the so-called mad cow disease, sheep's pruritus and, for example, fatal family insomnia, in which a person practically stops sleeping, and within 12-18 months dies against the background of progressive dementia. Another example of prion disease is Creutzfeldt-Jakob disease, which leads to death within six months or a year after the first symptoms appear; the disease affects the brain, therefore, disturbances of memory and attention develop, and then a disorder of coordination and convulsions. The latter is included in the list of the most dangerous diseases in the world, because doctors simply do not know what to do with it. It all began with the mysterious illness of Kuru in Papua New Guinea, which seemed to have no reasonable explanation.
How to find them
The story of the discovery of prions pulls on an adventure film with elements of fiction: it would seem that could be healthier than living on a beautiful island in the middle of the ocean, for example in New Guinea? But once upon a time, a disease of an unknown nature collapsed on the people of Fora, which was manifested by a very strong shaking, preventing a person from first walking, then standing and sitting. In the end, all that the sick person was capable of is lying and trembling. Paralysis followed, followed by death. For unusual clinical manifestations, the locals called the disease kuru (translated as "trembling"). A pediatrician and virologist Carlton Gaiduszek went to New Guinea to study infectious diseases, including the mysterious hen. He did it all: in 1976, Gaidušek received the Nobel Prize "for his discoveries concerning new mechanisms of the origin and spread of infectious diseases", sharing it with Baruch Blumberg, who discovered the hepatitis B virus.
However, Gaidushek did not discover the prions proper - he only suggested that the virus causes a "pathogenic particle" that is not visible under the microscope. To do this, the scientist had to spend a long time on the island, reveal a couple of hundreds of dead representatives of the handicap and even send their organs (especially Gaidushek was interested in the brain, which acquired a spongy structure in patients) to his colleagues from different countries. Ritual cannibalism became the cause of the epidemic among the Fore people: it was practiced even after the official ban of the authorities. The motives are prosaic: Faure believed that, together with eating the flesh of a dead person, his mind, abilities or talents would pass to them.
What is it all about?
At first, scientists thought they had found a new virus or a virus particle. Prions are really similar to viruses in that they do not have a cellular structure - that is, they do not consist of cells, unlike bacteria. The virus is a nucleic acid, that is, DNA or RNA, in the protein shell. But when prions were affected by means of destroying these acids, the dangerous infectious qualities remained. Gradually, it was concluded that a prion is just a protein, only with an unusual structure. All protein molecules have a certain three-dimensional configuration - if greatly simplified, this is how the chain of amino acids is laid in space. So, in prions, this structure is abnormal; surprisingly, with the "usual" chemical composition, it is this configuration anomaly that makes the prion deadly.
How does normal protein get abnormal?
The name of the squirrels working against man was given by the American doctor Stanley Prusiner. Combining the words protein (protein) and infection (infection), he received "prions", identified them as the newest type of biological pathogens and for the first time described the principle of their action. In 1997, he received the Nobel Prize for his work. Prusiner also discovered a prion-generating protein — it was called the prion protein, PrP. The most interesting thing is that the PrP coding gene is contained in the twentieth human chromosome - that is, it is in the DNA of any of us. But the chance of its transformation into a prion is minimal, and most people live quietly without the risk of prion diseases. However, just one mistake in protein synthesis can transform normal PrPC into abnormal PrP Sc.
As Valery Ilyinsky, a geneticist and CEO of Genotek, explains, prions are ordinary proteins that have acquired an unusual structure. This allows them to change the structure of similar proteins, also turning them into prions, that is, a process similar to infection occurs. To start the disease, the manifestation of the first damaged protein is necessary - this can occur either as a result of a spontaneous error during its synthesis, or after a prion from outside, from another person or animal. And then the chain reaction starts.
Rustam Ziganshin, Ph.D. in Chemistry, notes that the cause and mechanism for transforming the “normal” form of prion protein into dangerous is very poorly understood today. In in vitro experiments (in vitro) various additional factors are required for this transformation. At the same time, in animal experiments, prion diseases developed when the "normal" prion protein was injected into mice, which are completely devoid of the gene programming it. It is not clear what made him become "aggressive" in this case.
Eternal youth or inevitable death
Now they are talking about the fact that, for example, Alzheimer's disease or Parkinson's disease may be associated with the prion mechanism. If so, then we can expect the emergence of new methods of treatment or prevention of these serious diseases. Interestingly, prions are similar in mechanism of action and yeast proteins - it is quite possible that yeast will help in the study of these strange molecules. There is also talk about what prions will help to find a cure for various malignant tumors or HIV infection, and indeed they will become a “philosophical stone” that will lead humanity to eternal life or eternal youth. However, while these statements are unfounded.
Rustam Ziganshin explains that, like any research in the field of biology, the study of prion proteins expands the boundaries of our knowledge of living. From a practical point of view, the results can help to understand how a number of dangerous, yet incurable diseases are developing. Perhaps we will get a tool to deal with them. If you understand how normal protein turns out to be anomalous, and learn how to control this process, then maybe we will be able to start it in the opposite direction - that is, to transform pathological proteins into healthy ones, and with them to return health to the tissues and organs.
Photo: Flickr, ibreakstock - stock.adobe.com
