What does a molecular thermometer look like? This question is much more complicated than it might seem at first glance. Apparently, the “thermometer” used by the cell, which plays one of the most important roles in maintaining the stability of the cell proteome, is a system of transcription factors and specialized proteins - chaperones, incl. heat shock proteins, which respond not only to increased temperature (this is just the first of the discovered functions of this class of proteins), but also to other physiological influences that damage the cell.
Chaperones are a class of proteins whose main function is to restore the correct tertiary structure of damaged proteins, as well as the formation and dissociation of protein complexes.
The chaperone system responds to damage that occurs during the life of the cell and ensures the correct passage of folding - the folding of amino acid chains coming off the ribosomal “assembly line” into three-dimensional structures. Despite the obvious importance of this system, for a long time none of the specialists studying it even imagined that this molecular thermometer is also a kind of “fountain of youth” for the cell, and its study provides an opportunity to look at a number of diseases from a new, previously unknown side.
Proteins, which are the main product of the functioning of the genome, not only form the structure, but also ensure the functioning of all cells, tissues and organs. No disruptions in the synthesis of amino acid sequences; The formation, assembly and transport of protein molecules, as well as the removal of damaged proteins, is a critical aspect of maintaining the health of both individual cells and the entire body. Proteins are also the material necessary for the formation and effective functioning of “molecular machines” that provide biosynthesis processes, a process critical to ensuring the longevity of the body. Many problems are caused by disturbances in the fundamental process of protein folding. Disturbances in the functioning of the “OTK”, represented by heat shock proteins and chaperones, lead to the appearance and accumulation of errors. These errors disrupt the functioning of molecular mechanisms, which can lead to the development various diseases. The occurrence of such errors in neurons is fraught with truly terrible consequences, manifested by the development of such neurodegenerative diseases as multiple sclerosis, as well as Huntington's, Parkinson's and Alzheimer's diseases.
Discovered in 1962 by Ferruccio Ritossa, the heat shock response is described as a temperature-induced change in the organization of tightly packed chromosomes in cells. salivary glands Drosophila flies, leading to the formation of so-called “swells”. Such swellings, which look like cotton balls under a microscope, sandwiched between tightly packed sections of chromosomes, also appear when exposed to dinitrophenol, ethanol and salicylic acid salts.
It turned out that chromosome swellings are new transcription regions that begin the synthesis of new messenger RNAs within a few minutes of their occurrence. The protein products of this process are now commonly known as heat shock proteins, the best studied of which are Hsp90 and Hsp70. Proteins of this family regulate the folding of amino acid chains and prevent the appearance of incorrectly formed protein molecules in the cells of all living organisms.
In the late 1970s and early 1980s, using an original technique of cellular biochemistry to increase the number of messenger RNAs encoding the sequences of the corresponding proteins, scientists were able to clone the first heat shock genes of the fruit fly. At that time, experts were of the opinion that the heat shock reaction was characteristic exclusively of the Drosophila organism. At this stage, Richard Morimoto made his first contribution to the study of heat shock proteins. He collected an extensive collection of DNA from multicellular organisms and, using Southern blotting, demonstrated that they all contained analogues of the Hsp70 gene that were almost identical in structure. Around the same time, Jim Bardwell and Betty Craig from the University of Wisconsin at Madison identified coli(Escherichia coli) dnaK gene, also an analogue of Hsp70. The result of further detailed study of this issue was the understanding that heat shock genes, practically unchanged during evolution, are represented in the genomes of representatives of all five kingdoms of the living world.
The next advance in the chain of events that followed was the identification of a family of transcription factors that control the initiation of the first stage of the heat shock response. Several research groups from different universities took part in this work, including Morimoto's group. Scientists have demonstrated that increasing cell temperature causes a change in the shape of these transcription factors, which promotes their binding to the promoters of heat shock genes, which initiate the synthesis of heat shock proteins. Moreover, it turned out that unlike yeast, fruit flies and the nematode Caenorhabditis elegans, which have only one transcription factor for heat shock genes, human cells have as many as three such factors. Such a complex scheme for regulating the expression of the genes under study led scientists to think about their multifunctionality, which requires additional study.
Further studies showed that heat shock proteins themselves regulate the functioning of the transcription factor that initiates their production in cell nuclei. It has also become obvious that heat shock proteins perform the functions of molecular chaperones - they control the folding of amino acid chains, ensuring the formation of the correct spatial conformations of protein molecules, and also identify and eliminate failures in this process. Thus, it turned out that the cellular thermometer not only measures temperature, but also monitors the appearance of malformed and damaged proteins in the cell. Heat shock and other stressors flood the cell with abnormal proteins, to which chaperones respond by binding these proteins and releasing heat shock transcription factor 1 (Hsf1). Molecules of this factor spontaneously form trimers (complexes of three molecules) that bind to the corresponding regions of the genome, which in turn trigger the synthesis of heat shock proteins. The subsequent increase in the concentration of heat shock proteins to the required level according to the principle feedback suppresses the transcriptional activity of the Hsf1 transcription factor.
Studying the functioning of heat shock proteins on cell lines greatly limited the capabilities of researchers, since it did not provide information about the accompanying changes occurring throughout the body. So around 1999, Morimoto and his colleagues decided to switch to a new model: the roundworm C.elegans. They were particularly inspired by the work of Max Perutz, published in 1994, who found that the cause of the serious neurodegenerative disease Huntington's disease was a specific mutation of a gene called huntingtin. This mutation results in the synthesis of a protein variant containing an additional fragment from the long chain of the amino acid glutamine, which appears to disrupt normal process folding. The aggregation of such abnormal protein molecules in neurons leads to the development of Huntington's disease. The researchers suggested that studying proteins whose molecular formation is disrupted due to the expression of polyglutamine or similar reasons would help to understand the operation of the molecular thermometer.
While working to create animal models of the expression of proteins containing excess polyglutamine sequences in neurons and muscle cells, researchers found that the degree of aggregation and associated toxicity of such proteins is proportional to their length and the age of the organism. This led them to believe that suppression of the insulin-mediated signaling mechanism that regulates lifespan could affect the aggregation of polyglutamine-containing proteins. The results of further studies confirmed the existence of the proposed relationship and also demonstrated that the effect of the functioning of the Hsf1 transcription factor on the lifespan of the organism is mediated by an insulin-dependent signaling mechanism. These observations made it clear that the heat shock response is equally important both for the survival of the organism under conditions of acute stress and for the ongoing neutralization of the toxic effects of proteins that negatively affect the functioning and lifespan of cells.
The use of living organisms as an experimental model allowed scientists to translate research into qualitative new level. They began to pay attention to the mechanisms by which the body perceives and integrates information coming from outside at the molecular level. If stress affects the aging process, it is logical to assume that heat shock proteins, which detect the appearance and prevent the accumulation of damaged proteins in the cell, are quite capable of slowing down the development of the effects of aging.
The fact that many diseases associated with the accumulation of proteins prone to aggregation are characterized by symptoms of aging, and all diseases based on disturbances in the formation of protein molecules are associated with aging, suggests that temperature-sensitive metastable proteins lose their functionality due to as the body ages. Indeed, experiments on C.elegans have shown that the functioning of the mechanism triggered by the Hsf1 transcription factor, as well as other cell defense systems, begins to fade almost immediately after the organism reaches maturity. However, it turned out that activation of the Hsf1 transcription factor in the early stages of development can prevent disruption of the stability of protein molecules (proteostasis).
While this intriguing possibility may not apply to more complex multicellular organisms, all living things are made of proteins, so the results obtained from experiments on roundworms are likely to help scientists understand the mechanisms of human aging.
However, this is not the end of the story. The results of work recently carried out under the direction of Professor Morimoto indicate the existence of mechanisms for adjusting proteostasis that do not require direct interference with the functioning of the Hsf1 transcription factor. The researchers decided to conduct a classical genetic screening of C.elegans mutants that demonstrate disturbances in the formation of protein molecules in muscle cells. As a result, they found that the mutation affecting this process is located in the gene for a transcription factor that controls the production of a neurotransmitter gamma-aminobutyric acid(GABA). GABA controls the functioning of excitatory neurotransmitters and regulates muscle tone. An interesting fact is that any disturbance in the stability of the GABA-mediated mechanisms leads to hyperstimulation, causing postsynaptic muscle cells respond to non-existent stress, which leads to disruption of the formation of protein molecules. In other words, it turned out that the activity of neurons can influence the functioning of the molecular thermometers of other cells in the body, which further complicated the emerging picture.
If this mechanism extends to humans, then perhaps scientists will be able to develop a method of influencing neurons that leads to the activation of heat shock proteins in skeletal muscle cells and helps eliminate symptoms muscular dystrophy and other motor neuron diseases. Perhaps manipulation of these mechanisms will also make it possible to control the process of accumulation of damaged proteins associated with aging. However, unfortunately, not everything is as simple as we would like. In C.elegans, the development of the heat shock response in all adult somatic cells is controlled by a single pair of neurons. It appears that the activity of these neurons and the feedback mechanism allow cells and tissues to activate heat shock proteins according to their specific needs. The fact is that different tissues are characterized by different activity of protein biosynthesis, as well as different expression and character external influences. Therefore, a universal approach to managing the heat shock reaction is in principle impossible.
Armed with their work and promising ideas, Morimoto and several of his colleagues founded Proteostasis Therapeutics, which aims to identify therapeutic small molecules that can correct the pathological effects of the accumulation of misformed protein molecules. This approach is associated with a fairly large share of risk, since the level of heat shock proteins increases in many malignant diseases. However, Morimoto and his associates believe that the direction they are developing has too much potential to ignore.
about the author
Professor Richard Morimoto, after defending his doctoral dissertation, devoted his entire work to studying the functioning of heat shock proteins and their role in the aging of the body. Morimoto took his first steps in his chosen direction at Harvard University under the guidance of Dr. Matt Meselson. Currently, Richard Morimoto is the director of the Rice Institute for Biomedical Research, part of the Northwestern University in Evanston, Illinois, and also co-founded Proteostasis Therapeutics (Cambridge, Massachusetts).
Evgenia Ryabtseva
Portal “Eternal Youth” based on materials from The Scientist: Richard Morimoto,
Structural and functional changes under the influence of high temperatures. High temperature exposure primarily affects the fluidity of membranes, resulting in an increase in their permeability and the release of water-soluble substances from the cell. As a result, there is disorganization of many cell functions, in particular their division. So, if at a temperature of 20 °C all cells undergo the process of mitotic division, at 38 °C - every seventh cell, and at 42 °C - only every five hundredth cell.
Increased fluidity of membrane lipids, caused by changes in the composition and structure of the membrane during overheating, leads to loss of activity of membrane-bound enzymes and disruption of ETC activity. Of the main energy-producing processes - photosynthesis and respiration, the ETC of photosynthesis is the most sensitive, especially photosystem II (PS II). As for photosynthesis enzymes, the main enzyme of the C3 photosynthesis cycle, RuBP carboxylase, is quite resistant to overheating.
Overheating has a noticeable effect on the water regime of the plant, quickly and significantly increasing the rate of transpiration. As a result, the plant experiences water deficiency. The combination of drought with heat and high solar insolation has the maximum bad influence on crops, disrupting, along with photosynthesis, respiration and water regime, the absorption of mineral nutrition elements.
Molecular aspects of heat shock damage. Heat primarily damages proteins in the cell, especially enzymes, disrupting the process of de novo protein biosynthesis, inhibiting enzyme activity, and inducing degradation of existing proteins. As a result, pools of enzymes that are important for cell functioning both during periods of stress and subsequent repair may disappear. Most key plant enzymes are heat labile, including Rubisco, catalase and SOD. Rubisco inhibition is main reason reducing IF at high temperatures. Heat also inhibits the ability to convert sucrose to starch in barley, wheat and potatoes, indicating that one or more enzymes in the conversion chain are strongly inhibited by heat. The direct effect of heat on the activity of soluble starch synthase in wheat endosperm, both in vitro and in vivo, causes suppression of starch accumulation.
High temperatures inhibited catalase activity in several plant species, while the activity of other antioxidant enzymes was not inhibited. In rye, changes in catalase activity were reversible and did not leave visible damage after the cessation of heat, while in cucumber, the recovery of catalase activity was slowed down (inhibited) and accompanied by chlorophyll discoloration, indicating more significant oxidative damage. In corn seedlings grown at elevated temperatures (35 °C), SOD activity was lower than at relatively low temperatures. low temperatures(10°C).
The heat disrupted the integrity of the membranes, which led to their increased permeability to ions and solutions. At the same time, the activity of membrane-associated enzymes of photosynthesis, respiration and assimilate transport was disrupted. Heat increased saturation levels fatty acids membrane phospholipids of the ER. Under conditions of extreme heat, its membranes were selectively damaged, causing degradation of mRNA (3-amylase. At the same time, heat-induced leakage of substances through the membranes affects the redox potential of the main cellular compartments, which, in turn, disrupts the course of metabolic processes up to cell death.
Oxidative stress has recently been recognized as one of the most important negative effects of heat on plants. Heat causes an imbalance between the amount of solar radiation absorbed by pigments and the transport of electrons through cytochromes, a process called photoinhibition. Excess energy can be transferred to oxygen, which leads to the formation of ROS. The main areas of oxidative damage in cells are mitochondria and chloroplasts, where electron transport is disrupted. In chloroplasts, high temperature stress causes photoinhibition of photosynthesis and inactivation of catalase, which leads to the accumulation of ROS and chlorophyll bleaching. Photosystem II is recognized as the most sensitive to heat, leading to disintegration of the functional components of the PS II complex and, accordingly, disruption of electron transport between PS I and PS II, an increase in the flow of electrons to molecular oxygen and the formation of ROS. As a result, the FI decreases, which is the main cause of crop loss due to heat.
Heat shock proteins. The synthesis of heat shock proteins (HSPs) in response to increased temperature was discovered in 1974. It is characteristic of all types of living organisms, including higher and lower plants. HSP in all organisms is represented by a large set of polypeptides, which are usually named according to their molecular weight, expressed in kilodaltons (kDa). For example, HSP with a molecular weight of 70 kDa is called HSP 70. The significant role of HSP in the life of cells is indicated by the high conservation of their evolution. Thus, individual regions in the evolution of HSP 70 retain over 90% homology in bacteria and humans. Plant HSPs are represented by a group of high molecular weight (110-60 kDa) and low molecular weight (35-15 kDa) proteins. Distinctive features plants are the multiplicity of low-molecular HSPs and the high intensity of their synthesis during heat shock (HS).
HSP synthesis is a stress program triggered by heat shock and occurs when the temperature rises 8-10 °C above normal. Thus, in barley leaves, the maximum synthesis of HSPs is achieved at 40 °C, and in rice leaves - at 45 °C. Switching normal life cells to a stress program includes genome reprogramming associated with inhibition of gene expression, the activity of which is characteristic of life in normal conditions, and activation of TS genes. In plant cells, mRNA encoding HSPs is detected 5 min after the onset of stress. In addition, the disintegration of polysomes that synthesize proteins typical of normal conditions occurs, and the formation of polysomes that synthesize HSPs. The rapid activation of HSP synthesis at the level of not only transcription (RNA synthesis on DNA), but also translation (protein synthesis on mRNA) is achieved as a result of the coordination of many events. Heat shock causes changes in the mRNA synthesized in the cell before the shock, associated with the modification of protein translation factors and ribosomal proteins. In addition, HSP mRNAs differ from the mRNAs of ordinary proteins. As a result of HS, the synthesis of conventional proteins is weakened and then stopped and the protein synthesis apparatus switches to the synthesis of HSPs, which are detected in the cell already 15 minutes after the start of HS. The maximum synthesis is observed after 2-4 hours, then it decreases.
The synthesis of various HSPs occurs when different temperatures. In chloroplasts, the synthesis of high molecular weight HSPs was activated in the range of 34–42 °C, weakened at 44 °C, and sharply decreased at 46 °C. The induction of the synthesis of low molecular weight HSPs was especially noticeable at 40-42 °C. A significant inhibition of Rubisco synthesis occurred only at temperatures above 44 °C. Almost all of the detected chloroplast HSPs are encoded in the nucleus, synthesized in the cytoplasm, and then transported to the chloroplast, where they perform a protective function during HS. After the end of the heat shock, the synthesis of HSPs stops and the synthesis of proteins characteristic of the cell under normal temperature conditions resumes. In this case, HSP mRNA is quickly destroyed in cells at normal temperatures, while the proteins themselves can persist much longer, apparently providing an increase in cell resistance to heat. Prolonged exposure of cells to HSP conditions usually also leads to a weakening and cessation of HSP synthesis. In this case, the mechanisms of regulation of HSP gene expression are activated according to the feedback principle. The accumulation of HSPs in cells reduces the activity of their genes. Perhaps in this way the cell maintains the amount of HSP at the required level, preventing their overproduction.
As a rule, in response to an increase in temperature, the corresponding proteins are synthesized, which helps to increase the body's thermal resistance. The protective role of HSP is described by the model of a molecular chaperone (in translation from English - a guide, a mentor to a young person). IN extreme conditions HSPs “guard” the functioning of specific macromolecules and cellular structures, free cells from damaged components, which allows maintaining cellular homeostasis. The interaction of HSP 70 with other proteins depends on the ATP/ADP ratio. It is believed that HSP 70, in a complex with ADP, retains the unwoven protein, and the replacement of ADP with ATP leads to the release of this protein from the complex with HSP 70.
In accordance with this model, HSPs increase the thermal stability of cells, providing the following processes: energy-dependent stabilization of the native structure of proteins; correct assembly of oligomeric structures under hyperthermia conditions; transport of substances across organelle membranes; disaggregation of incorrectly assembled macromolecular complexes; liberation of the cell from denatured macromolecules and recycling of the monomers included in them with the help of ubiquitins. Ubiquitins are low molecular weight heat shock proteins, the attachment of which to a polypeptide makes it a target for proteases. This is a kind of “death mark” for proteins. With their help, proteins that are damaged and unfinished as a result of the action of HS are culled and removed.
A number of facts support the protective function of HSP in HS. In particular, it has been shown that turning off protein synthesis with specific inhibitors during HS, when HSP synthesis occurs, leads to cell death. Cells can be hardened, increasing their thermal stability by first briefly exposing them to elevated temperatures. The conditions for such hardening coincide with the conditions for inducing HSP synthesis. Interestingly, the synthesis of HSPs in plants is induced not only by HSPs, but also, for example, by cadmium salts and arsenite, treatment with which increases the resistance of cells to heat. It is also important to emphasize that changes in the gene structure (mutations) that disrupt the synthesis of HSPs lead to a loss of cell resistance to heating. Further studies of the specific function of each HSP under stress will reveal molecular mechanisms formation and functioning of protective properties in TS.
Most HS proteins have related proteins in cells, which are synthesized at normal temperatures constantly or during certain phases of ontogenesis. It turns out that these proteins, in particular HSP 70, attach to other proteins, causing them to unfold and preventing their aggregation. The latter can prevent the protein from acquiring the native conformation necessary for its functional activity. The unfolding of proteins by HSPs is necessary for their penetration through the membrane of chloroplasts, mitochondria, and the ER. Since protein aggregation sharply increases with increasing temperature, activation of HSP 70 synthesis under these conditions should protect proteins from irreversible damage. HSPs are present in all cell compartments, in particular the nucleus and nucleoli, where they accumulate during HS. HSP 70 promotes the passage of the precursors of chloroplast and mitochondrial proteins synthesized in the cytoplasm through the membrane, playing a role in the biogenesis of these organelles. HSP 60, also related to chaperones, is also called chaperonins. These proteins ensure the correct assembly of the quaternary structure of cellular proteins, such as the key photosynthetic enzyme Rubisco, which consists of eight large and eight small subunits. The group of chaperones also includes HSP 90, which plays an important role in the formation of the complex steroid hormones with their receptors. In addition, HSP 90 forms complexes with some protein kinases, controlling their activity. Protein kinases are known to phosphorylate a variety of cellular proteins, regulating their activity.
More than 30 low-molecular-weight (15-35 kDa) HSPs were found in plants, localized mainly in cytoplasmic heat shock granules that appear during HS and disappear after it. Their main function is to protect “pre-shock” mRNAs, which allows the latter to be used for protein synthesis after the end of shock. Low molecular weight HSPs are also found in other compartments, in particular in chloroplasts. It is believed that they protect thylakoid membranes, where the processes of the light phase of photosynthesis are localized, from HS.
In some plants, constitutive (non-induced) synthesis of HSPs has been detected during the formation, in particular, of pollen. It is possible that pre-shock HSPs ensure its thermal stability during HS. In addition to HSPs, heat induces the expression of other classes of proteins, in particular calmodulin.
Metabolism under heat shock conditions. There are very few targeted studies of plant metabolism under the influence of HS, and in these experiments both HS and drought often acted simultaneously. This is very important point, since the response of plants to a combination of drought and HS is different than the response to individual stressors. Thus, under a combination of stresses, plants accumulated several soluble sugars, including sucrose, maltose, trekallose, fructose and glucose. Under the influence of drought, proline accumulates, but under the influence of HS, as well as a combination of HS and drought, proline did not accumulate in plants. Under HS conditions, proline or its intermediate (pyrroline-5-carboxylate) is toxic, so proline is not suitable as a compatible osmolyte. With the simultaneous action of HS and drought, the glutamine content increases sharply. Apparently, when proline biosynthesis is inhibited, glutamate is transformed into glutamine. At the same time, genes encoding starch breakdown and lipid biosynthesis are activated, and the expression of genes encoding hexokinase, glucose-6-phosphate dehydrogenase, fructokinase and sucrose-UDP-glucosyltransferase also increases. It is changes in gene expression at the transcription level that represent the main factor in the reprogramming of carbohydrate metabolism.
Under the influence of HS on Arabidopsis seedlings, a synchronous increase in the size of the pools of a number of amino acids and amides (asparagine, leucine, isoleucine, threonine, alanine and valine) obtained from AP and PVA was established. In addition, the content of carbohydrates increased: maltose, sucrose, galactinol, myoinositol, raffinose and monosaccharides, cell wall precursors. Already after 6 hours, the concentrations of b-alanine, glycerol, maltose, sucrose, and trekalose increased.
Photosynthesis, transpiration and respiration. An indicator closely related to the regulation of CO2 and H2O metabolism in plants is stomatal conductance. Extensive evidence suggests that high temperatures induce stomatal closure, which can be seen as an indirect response to the temperature dependence of water vapor pressure deficits and leaf respiration. Thus, partial closure of stomata is a consequence of an increase in intracellular CO2 concentration. However, the desired closure of stomata does not lead to a decrease in photosynthesis, since the temperature dependences of stomatal conductance and IF do not coincide. Thus, stomatal conductance increases at temperatures where photosynthesis is irreversibly inhibited.
Although stomatal conductance does not appear to directly influence IF, it does help regulate transpiration, which, by controlling leaf temperature, influences the heat tolerance of photosynthesis. In the crops of some crops, with sufficient moisture supply, the air temperature due to thermoregulation can be almost 8 °C lower than the air temperature above the crop. At the same time, if there is a moisture deficit in the soil, the opposite picture can be observed - the temperature of the leaves in the crop exceeds the ambient air temperature by almost 15 °C, which increases negative impact water deficit at IF.
The rate of net photosynthesis of wheat and most C3 crops is quite stable in the range of 15-30 °C. Below and above this temperature range, IF decreases by 5-10% for each degree (Fig. 3.1). The relatively small change in net photosynthesis in the range of 15-30 °C should not hide the fact that gross photosynthesis actually increases with increasing temperature. However, due to the simultaneous increase in ID of the whole plant and especially photorespiration, the intensity of net photosynthesis changes little.
There are noticeable differences between C3 and C4 crops in this regard, with the optimal intensity of net photosynthesis in C4 species observed at higher temperatures (30-40 °C). Their photorespiration is insignificant, as a result of which the increase in CO2 fixation with increasing temperature is not masked by photorespiratory costs. Indeed, the higher temperature optimum for net photosynthesis in C4 species compared to C3 species is explained by lower respiratory costs at elevated temperatures in the former. Irreversible changes in their photosynthetic apparatus are observed only when the temperature exceeds 40 °C, mainly due to damage to PS II that occurs within a few minutes after the onset of the action of HS, which has a decisive effect on yield.
Heat shock heat shock- heat shock.
Stressful state of the body after exposure elevated temperature, in particular, T.sh. used to induce polyploidy<induced polyploidy> mainly for animals that reproduce in water (fish, shellfish): the water temperature is increased to 29-33 o C for 2-20 minutes. ( normal temperature incubation is usually 15-20 o C) after 3-10 minutes. (induction of triploidy) or after 20-40 minutes. (induction of tetraploidy) after fertilization; also able T.sh. analyze the activity of specific heat shock proteins<heat-shock proteins>, pouf activity<puffing> in fruit flies (in this case T.sh. at 41-43 o C).
(Source: "English-Russian Dictionary genetic terms." Arefiev V.A., Lisovenko L.A., Moscow: Publishing House VNIRO, 1995)
See what “heat shock” is in other dictionaries:
Heat shock- * ceplav shock * heat shock is a stressful state of the body due to exposure to elevated temperature. T. sh. used: a) to induce polyploidy (see) in fish, mollusks, incubation of individuals after fertilization at tо = 29-33 °C (instead of ... ... Genetics. encyclopedic Dictionary
heat shock- Stressful state of the body after exposure to elevated temperature, in particular, T.sh. used to induce polyploidy mainly in water-reproducing animals (fish, shellfish): the water temperature is increased to 29-33 oC for 2-20 minutes... ... Technical Translator's Guide
Thermal shock- Syn: Thermal exhaustion. Occurs when overheating due to insufficient response of the heart vessels to extreme high temperature, develops especially often in older people taking diuretics. Shows weakness... Encyclopedic Dictionary of Psychology and Pedagogy
OVERHEATING AND HEAT STROKE- honey Overheating (heat syncope, heat prostration, heat collapse) and heat stroke (hyperpyrexia, sunstroke, overheating of the body) pathological reactions of the body to high temperature environment, Related… … Directory of diseases
- (English HSP, Heat shock proteins) is a class of functionally similar proteins, the expression of which increases with increasing temperature or under other conditions that stress the cell. Increased expression of genes encoding thermal proteins... ... Wikipedia
A tetramer consisting of four identical p53 protein molecules. They are interconnected by domains responsible for oligomerization (see text). p53 (p53 protein) is a transcription factor that regulates cell cycle. In a non-mutated state... ... Wikipedia
If the temperature rises, a living organism reacts to this by producing peculiar compounds called “heat shock proteins.” This is how a person reacts, this is how a cat will react, this is how any creature reacts, since it consists of living cells. However, it is not only an increase in temperature that provokes the synthesis of the heat shock protein of chlamydia and other species. Severe stress situations are often triggered.
general information
Since heat shock proteins are produced by the body only in specific situations, they have a number of differences from normally produced compounds. The period of their formation is characterized by inhibition of the expression of the main protein pool, which plays an important role in metabolism.
HSP-70 of eukaryotes, DnaK of prokaryotes - this is a family into which scientists have combined heat shock proteins that are important for survival at the cellular level. This means that thanks to such connections, the cell can continue to function even in a situation where stress, heat, and an aggressive environment oppose it. However, proteins of this family can also participate in processes occurring under normal conditions.
Biology at the microscopic level
If the domains are 100% identical, then eukaryotes and prokaryotes are more than 50% homologous. Scientists have proven that in nature, among all protein groups, the 70 kDa HSP is one of the most conservative. Studies devoted to this were done in 1988 and 1993. Presumably, the phenomenon can be explained through the chaperone functionality inherent in heat shock proteins in intracellular mechanisms.
How it works?
If we consider eukaryotes, then under the influence of heat shock the HSP genes are induced. If a certain cell has escaped stressful conditions, then the factors are present in the nucleus and cytoplasm as monomers. This compound does not have DNA binding activity.
When experiencing stressful conditions, the cell behaves as follows: Hsp70 is cleaved off, which initiates the production of denatured proteins. HSP forms trimmers, the activity changes its character and affects DNA, which leads over time to the accumulation of components in the cell nucleus. The process is accompanied by a multiple increase in chaperone transcription. Of course, the situation that provoked this passes over time, and by the time this happens, Hsp70 can again be incorporated into the HSP. DNA-related activity fades away and the cell continues to function as if nothing had happened. This sequence of events was identified back in 1993 in studies on HSP conducted by Morimoto. If the body is affected by bacteria, then HSPs can concentrate on the synovium.
Why and why?
Scientists were able to reveal that HSPs are formed as a result of the influence of a variety of negative situations that are dangerous to the life of the cell. Stressful, damaging influences from the outside can be extremely diverse, but lead to the same option. Due to HSP, the cell survives the influence of aggressive factors.
It is known that HSPs are divided into three families. In addition, scientists have discovered that there are antibodies to heat shock protein. HSPs are divided into groups based on molecular weight. Three categories: 25, 70, 90 kDa. If there is a normally functioning cell in a living organism, then inside it there will probably be various proteins mixed together, quite similar. Thanks to HSP, denatured proteins, as well as those that have folded incorrectly, can become a solution again. However, besides this function, there are some others.
What we know and what we guess
Until now, the heat shock protein of chlamydia, as well as other HSPs, has not been fully studied. Of course, there are some groups of proteins about which scientists have a fairly large amount of data, and there are others that have yet to be mastered. But now science has reached the level where knowledge allows us to say that in oncology, heat shock protein can be a truly useful tool to defeat one of the most terrible diseases of our century - cancer.
Scientists have the largest amount of data on Hsp70 HSPs, which are capable of binding to various proteins, aggregates, complexes, even abnormal ones. Over time, release occurs, accompanied by the ATP compound. This means that a solution appears in the cell again, and proteins that have incorrectly undergone the coagulation process can be subjected to this operation again. Hydrolysis, ATP coupling are the mechanisms that made this possible.
Anomalies and norms
It is difficult to overestimate the role of heat shock proteins for living organisms. Any cell always contains abnormal proteins, whose concentration can increase if there are external prerequisites for this. The typical story is overheating or infection. This means that in order for the cell to continue to function, it is urgent to generate more HSPs. The transcription mechanism is activated, which initiates the production of proteins, the cell adapts to changing conditions and continues to function. However, along with already known mechanisms, much remains to be discovered. In particular, antibodies to the heat shock protein of chlamydia are such a fairly large field for the activity of scientists.
HSPs, when the polypeptide chain increases and they find themselves in conditions that make it possible to enter into contact with it, allow them to avoid nonspecific aggregation and degradation. Instead, folding occurs normally, with the necessary chaperones involved in the process. Hsp70 is additionally required for the unfolding of polypeptide chains with the participation of ATP. By means of HSP, it is possible to ensure that non-polar regions are also susceptible to the influence of enzymes.
HSP and medicine
In Russia, FMBA scientists were able to create new drug, using heat shock protein to construct it. The cancer cure presented by the researchers has already passed initial testing on experimental rodents affected by sarcomas and melanomas. These experiments made it possible to confidently say that a significant step forward has been made in the fight against oncology.
Scientists have suggested and were able to prove that heat shock protein is a medicine, or rather, can become the basis for an effective drug, largely due to the fact that these molecules are formed in stressful situations. Since they are initially produced by the body to ensure the survival of cells, it has been suggested that with proper combination with other agents, even tumors can be fought.
HSP helps the drug detect affected cells in a sick body and cope with incorrect DNA in them. It is assumed that the new drug will be equally effective for any subtype malignant diseases. It sounds like a fairy tale, but doctors go even further - they assume that a cure will be available at absolutely any stage. Agree, such a heat shock protein for cancer, when it passes all the tests and confirms its reliability, will become an invaluable acquisition for human civilization.
Diagnose and treat
Most detailed information about hope modern medicine said Dr. Simbirtsev, one of those who worked on the creation of the medicine. From his interview, you can understand by what logic scientists built the drug and how it should bring effectiveness. In addition, it can be concluded whether the heat shock protein has already passed clinical trials or is still to come.
As stated earlier, if the body does not experience stressful conditions, then the production of BS occurs in an extremely small volume, but it increases significantly with changes in external influences. At the same time, the normal human body is not able to produce such an amount of HSP that would help defeat the emerging malignant neoplasm. “What happens if you introduce BTS from the outside?” - the scientists thought and made this idea the basis for research.
How is this supposed to work?
To create a new medicine, scientists in laboratory conditions have recreated everything necessary for living cells to begin producing HSPs. For this purpose, a human gene was obtained, which underwent cloning using the latest equipment. Bacteria studied in laboratories were modified until they began to independently produce the protein so desired by scientists.
Scientists, based on the information obtained during research, have drawn conclusions about the influence of HSP on human body. To do this, we had to organize a squirrel. This is not at all easy to do: we had to send samples into the orbit of our planet. This is due to the fact that earthly conditions are not suitable for the correct, uniform development of crystals. But space conditions make it possible to obtain exactly those crystals that scientists needed. Upon returning to their home planet, the experimental samples were divided between Japanese and Russian scientists, who took up their analysis, as they say, without wasting a second.
And what did they find?
So far, work in this direction is still underway. A representative of the team of scientists said that it was possible to establish precisely that there is no exact connection between the HSP molecule and the organ or tissue of a living being. And this speaks of versatility. This means that if the heat shock protein finds application in medicine, it will become a panacea immediately from huge amount diseases - no matter which organ is affected by a malignant neoplasm, it can be cured.
Initially, scientists prepared the drug in liquid form - it was injected into experimental subjects. Rats and mice were taken as the first specimens to test the product. It was possible to identify cases of cure both at initial and at late stages development of the disease. The current stage is called preclinical testing. Scientists estimate the time frame for its completion to be at least a year. After that the time will come clinical trials. A new product, perhaps a panacea, will be available on the market in another 3-4 years. However, as scientists note, all this is realistic only if the project finds funding.
To wait or not to wait?
Of course, doctors' promises sound attractive, but at the same time they rightly cause mistrust. How long has humanity suffered from cancer, how many victims has this disease had in the last few decades, and here they promise not only effective drug, but a real panacea - for any type, for any period. How can you believe this? A worse than that- believe, but not wait, or wait, but it turns out that the remedy is not as good as expected, as promised.
Drug development is a technique genetic engineering, that is, the most advanced field of medicine as a science. This means that if successful, the results should indeed be impressive. However, at the same time this means that the process is extremely expensive. As a rule, investors are willing to invest quite a lot of money in promising projects, but when the topic is so loud, the pressure is great, and the time frame is quite vague, the risks are assessed as enormous. Now these sound optimistic forecasts for 3-4 years, but all market experts know well how often the time frame extends to decades.
Amazing, incredible... or is it?
Biotechnology is an area that is closed to understanding for the average person. Therefore, we can only hope for the words “success of preclinical trials.” The working name of the drug was “Heat Shock Protein”. However, HSP is only the main component of the drug, which promises to be a breakthrough in the market of drugs against oncology. In addition to it, the composition is supposed to include a number of useful substances, which will guarantee the effectiveness of the product. And all this became possible thanks to the fact that latest research HSPs showed that the molecule not only helps protect living cells from damage, but also acts as a kind of “guiding finger” for the immune system, helping to identify which cells are affected by the tumor and which are not. Simply put, when HSP appears in the body in a sufficiently large concentration, scientists hope that the immune response itself will destroy the diseased elements.
Hope and wait
To summarize, we can say that the new anti-tumor product is based on the fact that the body itself has a remedy that could destroy the tumor, it’s just naturally quite weak. The concentration is so low that no therapeutic effect you can't even dream of it. At the same time, some of the HSPs are found in cells that are not affected by the tumor, and the molecule will not “go away” from them. Therefore, delivery is necessary useful substance from the outside - so that it further directively influences the affected elements. By the way, so far scientists assume that the drug will not even have side effects - and this is with such high effectiveness! And they explain this “magic” by the fact that studies have shown that there is no toxicity. However, final conclusions will be made when preclinical trials come to an end, which will require at least a year.
Material with a very optimistic subtitle “Genetically engineered drug for all types and stages of malignant tumors patients can get it in three to four years.”
However, anyone who knows anything about therapy oncological diseases, at the sight of such a forecast, at best, he will raise his eyebrows in surprise, and at worst, he will be indignant. We tell you what’s wrong with the latest “scientific sensation.”
What's happened?
The development of the drug, which was described in Izvestia, is being carried out at the State Research Institute of Highly Pure Drugs of the Federal Medical and Biological Agency (FMBA) of Russia. Deputy Director for Scientific Work of the Institute, Corresponding Member of the Russian Academy of Sciences and Doctor medical sciences, Professor Andrei Simbirtsev, in this article entitled “In Russia they created a cure for cancer and tested it in space,” told an Izvestia correspondent about the “heat shock protein,” which was crystallized in zero gravity on the ISS, and is now undergoing preclinical testing.
Currently, the research is being carried out with a grant from the Ministry of Education and Science, and scientists plan to find 100 million rubles for clinical trials with the help of private investors and a 50% state co-financing program. To attract him, the developers are going to “knock on all doors, because the drug is unique. We are on the verge of discovering a completely new cancer treatment. It will help people with incurable tumors.”
“We are already producing the drug at the production sites of the research institute,” Andrei Simbirtsev tells enthusiastic journalists, adding that in this moment are being tested on mice, and it will reach patients in just three to four years.
What's the catch?
All this sounds very inspiring, but heat shock proteins have actually been known for a long time, but for some reason people still have not made them a panacea for all types of cancer. This is a fairly large family of proteins that are activated in response to stress when temperature increases (and sometimes decreases). They help the cell fight the consequences of degradation of the structure of other proteins. Most famous example such a change is the collapse of the main component egg white, albumin, when frying or boiling, when it turns from transparent to white. So, heat shock proteins eliminate the consequences of these changes: they “repair” or finally utilize degraded structures. Many heat shock proteins are also chaperones that help other proteins fold correctly.
Reference:
Chaperones are a class of proteins whose main function is to restore the tertiary or quaternary structure of proteins; they are also involved in the formation and dissociation of protein complexes.
Heat shock proteins are found in all cells. However, in different cells (especially tumor cells, which differ greatly in different types cancer both from each other and from normal cells in the body), these proteins behave differently. For example, in some types of cancer, the expression of the HSP-70 protein can be either increased (in malignant melanoma) or decreased (in kidney cancer).
To understand what kind of protein we are talking about and whether it is really used in cancer therapy and can help with all types of it, we talked to Dr. biological sciences Alexander Sapozhnikov. This scientist is the head of the laboratory of cellular interactions at the Institute of Bioorganic Chemistry named after M.M. Shemyakin and Yu.A. Ovchinnikov RAS, which has been working on one of the most promising heat shock proteins for development in this direction for many years. He commented on this article:
“I won’t say that this is nonsense, but this is absolutely incorrect information. The author of the idea of using heat shock proteins with a molecular weight of 70 kilodaltons (the so-called HSP-70, in English HSP70) is my friend and colleague Boris Margulis. He works at the Institute of Cytology in St. Petersburg.
He and his wife Irina Guzhova have been working on this protein all their lives (I have also been working on it for many years, but not with research related to cancer therapy). Formally, the head of the laboratory is Irina, who studies how proteins are associated with neurodegenerative diseases, and Boris is the head of the department. He is the first person in the world to propose the use of a “naked” protein, not loaded with any tumor-associated antigens.
I did not believe in his ideas about this use of this protein (in fact, it has not yet been proven that it will be effective). If we “dance from the stove,” there is a certain Hindu, Pramod Srivastava, who was born in India, but studied, lives and works in America. A long time ago, he not only made a “vaccine” against a tumor using HSP-70, but also opened a clinic and treats cancer patients with it. Srivastava isolates this protein directly from the tumor: he takes biopsies from patients, isolates it from pieces of tissue (there are special ways to obtain very high faction this protein).
However, the protein, which is obtained from the tissues of cancer patients, is in strong connection with tumor-associated peptides - those signs of the tumor that are recognized by the immune system. Therefore, when this complex is administered to patients, large quantity patients, an immune response is produced, and a positive effect is obtained for the patient.
In fact, according to statistics, this effect does not exceed the effect of chemotherapy. But still, chemotherapy “poisons” the body, but such “vaccination” does not “poison” the body. This is a very long history; this approach has been used in the clinic for a long time.
Alexander Sapozhnikov. Doctor of Biological Sciences, Professor
As for Boris Margulis, he (in particular, based on my laboratory) showed (and published the results of his work) that if pure protein, without any tumor load, is added to tumor cells, then this exogenous protein causes tumor cells to expose the same tumor-associated peptides that are normally located inside these cells, in the cytoplasm. Then the immune system will recognize them, and the body will reject these cells on its own and fight the tumor.
This has been shown in culture in vitro, that is, not in the body, but in a test tube. In addition, Boris Margulis claimed only for childhood leukemia, since he is connected with clinicians in St. Petersburg. What Simbirtsev said in his interview is an expansion of this method of using naked, pure protein.
The mechanism of action of this pure protein is to force the tumor to pull to the surface (as Margulis himself called it, “squeeze out”) these peptides with their endogenous protein. This protein is present in all cells, and there is not a single cell in the world that does not have this protein. This is a very ancient, very conservative protein, everyone has it (I’m not talking about viruses now).
Margulis himself would not have carried out preclinical research; he received (five years ago) a grant together with the Institute of Highly Pure Drugs. Apparently, this institute is where this Simbirtsev works, I have heard his name many times, but since this is the Federal Medical-Biological Agency, which includes the Institute of Immunology on Kashirka, where I worked for many years, then most likely this is the Institute highly pure drugs, with which he received a grant for preclinical research. IN Soviet years it was the Third Directorate of the Ministry of Health. It was with this institute that a grant for the preclinic was received from the Ministry of Education for 30 million for three years, which ended two years ago.
The Institute of Highly Pure Preparations did all the paperwork, they reported on their grant, as for next stage, promoting the drug, money is also needed there. This is the first stage of clinical trials. Here Boris Margulis, as far as I understand, has already moved away from development, leaving it to the Institute of Highly Pure Preparations.
They make this protein, they made biotechnology, I even have it in the refrigerator, Boris gave it to me for testing. They make it in large quantities and store it in lyophilized form (dry) in sterile ampoules. Actually, this drug should be used, maybe with some additives, in clinical trials. But this requires money.
Having accidentally seen the news with Simbirtsev’s interview, I read it, sent it to Margulis, and asked if he had read it. Boris answered me that Andrey (whom he knows well) did something stupid, he didn’t even refer to the authors. The author of this idea (to use pure protein as an antitumor drug in oncology), I repeat, is Boris Margulis. But, as far as I’ve heard from him lately, he has moved away from this issue.
I'm working on this protein, but as an immunomodulator, like my laboratory. We worked a little with antitumor properties, in mouse models. There were really good results there. I mean "naked" protein, it simply has immunostimulating properties. By the way, the big question is what is the reason for its immunostimulating properties: the protein itself or some small impurities, for example lipopolysaccharides. This protein is obtained in bacterial culture (in E.coli), this is the most common technique for producing recombinant proteins. Lipopolysaccharides (LPS) are a component of the bacterial cell wall, and it is very difficult to completely purify a culture of this impurity. Of course, they clean it, but some tiny concentrations remain. These LPS impurities also have immunostimulating properties simply because the immune system has evolved to develop its own defenses against bacteria. As soon as the “smell” of bacteria appears in the body, the immune system is activated. Therefore, many authors now believe that the immunostimulating properties of this protein, which also modulate the antitumor response, are caused not by HSP as such, but by its admixture. But this question is scientific, debatable and has nothing to do with practice.
Now, I repeat, Boris Margulis is moving away from this topic, from oncology, and is working on small molecules that can regulate the production of this protein. He contacted chemists who know how to make inhibitors - such specific kinases, some enzymes inside cells that stop their work. Inhibitors can tell some enzyme: “No, you have no right to work.”
This is done very simply: all enzymes have a substrate binding center, and if you take some small molecule that is built into this substrate binding center, it will no longer be able to process this substrate. Boris is now working on molecules that inhibit the intracellular synthesis of this HSP-70. And, indeed, such molecules are very relevant, and not only for fundamental biology, but also for practice and clinical medicine.”
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