M. B. Evgen’ev

Molecular mechanisms underlying thermal adaptation of xeric animals

For many years, we and our collaborators have investigated the adaptive role of heat shock proteins in different animals, including the representatives of homothermic and poikilothermic species that inhabit regions with contrasting thermal conditions. Adaptive evolution of the response to hyperthermia has led to different results depending upon the species. The thermal threshold of induction of heat shock proteins in desert thermophylic species is, as a rule, higher than in the species from less extreme climates. In addition, thermoresistant poikilothermic species often exhibit a certain level of heat shock proteins in cells even at a physiologically normal temperature. Furthermore, there is often a positive correlation between the characteristic temperature of the ecological niche of a given species and the amount of Hsp70-like proteins in the cells at normal temperature. Although in most cases adaptation to hyperthermia occurs without changes in the number of heat shock genes, these genes can be amplified in some xeric species. It was shown that mobile genetic elements may play an important role in the evolution and fine-tuning of the heat shock response system, and can be used for direct introduction of mutations in the promoter regions of these genes.

Mobile elements and genome evolution

Mobile elements (MEs) are an important component of the genome in all eukaryotes and prokaryotes. MEs are divided into two large classes differing in the mechanism of transposition. Class I MEs are transposed via reverse transcription of their RNA transcripts. Class II MEs code for transposase, which acts at the DNA level and recognizes the ends of the cognate ME. The review considers the distribution of MEs from different classes in various genomes, individual chromosomes, and chromatin types. There is ample evidence for an important role of MEs in the regulation of cell genes and evolution of complex eukaryotic genomes. It is thought that ME invasion and subsequent amplification act as a main morphogenetic factor ensuring adaptation of populations to environmental changes and, in some cases, cause rapid speciation.

Parallelism and paradoxes on viability and the life span of two loss-of-function mutations: Heat shock protein transcriptional regulator hsf 1 and l(2)gl tumor suppressor in Drosophila melanogaster

In this study we analyzed how a dosage decrease in mono- and diheterozygotes on both lethal alleles of the lgl-gene and hsf heat shock regulator influences viability and life span at optimal and high temperature 29°C conditions. We found that hsf1/+ (1 dosage of active hsf -factor) heterozygote animals had significantly increased viability (up to 30–39%) in case of its development from egg to imago under the stress of 29°C. However, this stress-protective effect of a decreased dosage of HSF1 was suppressed in diheterozygotes, while the dosage of tumor suppressor lgl was simultaneously decreased. Under stress temperature conditions, a decrease in dosage of one of the alleles also increased the average life span and delayed aging, especially in the case of maternal inheritance of each of the loss-of-function mutations. In diheterozygotes the average life span had intermediate meanings. However, in diheterozygote males under stress conditions the positive longevity effect of hsf was suppressed in the presence of the lgl-mutation. Paradoxically, that decrease of expression of each of the studied vital genes provided a positive effect on both viability and life span under stress conditions. However, a simultaneous dosage decrease of two loss-of-function alleles in diheterozygotes resulted in disbalanced effects on the organism level. The received data indicate interaction between HSF1 and LGL gene products during ontogenesis and stress-defending processes.

The evolution of heat shock genes and expression patterns of heat shock proteins in the species from temperature contrasting habitats

Heat shock genes are the most evolutionarily ancient among the systems responsible for adaptation of organisms to a harsh environment. The encoded proteins (heat shock proteins, Hsps) represent the most important factors of adaptation to adverse environmental conditions. They serve as molecular chaperones, providing protein folding and preventing aggregation of damaged cellular proteins. Structural analysis of the heat shock genes in individuals from both phylogenetically close and very distant taxa made it possible to reveal the basic trends of the heat shock gene organization in the context of adaptation to extreme conditions. Using different model objects and nonmodel species from natural populations, it was demonstrated that modulation of the Hsps expression during adaptation to different environmental conditions could be achieved by changing the number and structural organization of heat shock genes in the genome, as well as the structure of their promoters. It was demonstrated that thermotolerant species were usually characterized by elevated levels of Hsps under normal temperature or by the increase in the synthesis of these proteins in response to heat shock. Analysis of the heat shock genes in phylogenetically distant organisms is of great interest because, on one hand, it contributes to the understanding of the molecular mechanisms of evolution of adaptogenes and, on the other hand, sheds the light on the role of different Hsps families in the development of thermotolerance and the resistance to other stress factors.

Heat-shock protein HSP70 reduces the secretion of TNFα by neuroblastoma cells and human monocytes induced with beta-amyloid peptides

The progress of neurodegeneration in Alzheimer’s disease is closely associated with inflammatory processes in the brain tissues induced by beta-amyloid peptides (Aβ). In this paper, we showed that Aβ(1-42) and isoAβ(1-42) in human neuroblastoma cells SK-N-SH and promonocyte THP-1 activated the production of tumor necrosis factor (TNFα). Notably, isoAβ(1-42) had the strongest effect on the increase in the level of TNFα. The addition of recombinant heat-shock protein HSP70 reduces TNFα production induced by Aβ, which leads to a decrease in neuronal cell damage at the organism level.

Exogenous heat shock protein HSP70 reduces response of human neuroblastoma cells to lipopolysaccharide

The effect of exogenous heat shock protein HSP70 and lipopolysaccharide (LPS) on the production of reactive oxygen species (ROS), TNFα secretion, and mRNA expression by human neuroblastoma SK-N-SH cells. It was shown that exogenous HSP70 protects neuroblastoma cells from the action of LPS. The protection mechanism of HSP70 includes a reduction in the production of ROS and TNFα and a decrease in the expression of TLR4 and IL-1β mRNA in SK-N-SH cells induced by LPS.

Exogenous heat shock protein HSP70 modulates lipopolysaccharide-induced macrophage activation

320 Innate immunity cells, including macrophages, play an important role in the defense of a mammalian body against pathogenic bacteria. Lipopolysacchaa rides (LPS) produced by Grammnegative bacteria actii vate macrophages. They begin to produce reactive oxygen species (ROS), synthesize and secrete proinn flammatory cytokines, and raise the production of heat shock proteins (HSP), including HSP70 [1]. After entering the bloodstream, LPSs interact with LPSSbinding protein and, subsequently, with the CD14 receptor of target cells. Then, LPSs are transs ferred from CD14 to lymphocyte antigen 96 (MDD2) to form two identical complexes including Tollllike receptor 4 (TLR4), MD2, and LPS. Then, a hett erodimeric receptor complex is formed in target cell membranes through interaction of the phosphate moii eties of LPS from one complex with TLR4 of the other complex [2]. The next step is the transduction of the signal from the receptor to transcription factors of tarr get cells to elicit the cell response. Early steps of the response are characterized by elevated ROS producc tion and adhesion factor expression. Then, proinflamm matory cytokines are produced. The first of them to be secreted is TNFFα [3]. Most enterobacteria E. coli contain the S form of LPSs. It includes hydrophobic lipid A, an oligosaccha ride core, and OOantigen. In addition to the S form, enterobacteria produce coreedeficient LPS molecules (R chemotypes) containing lipid A and cores of differr ent lengths. The molecules with abnormal cores are designated as Rb–Re chemotypes, and molecules with a fulllsize external core, as the Ra chemotype [4]. It is supposed that the LPS receptor complex can also bind heat shock proteins with M r = 70 kDa (HSP70) [5]. Our earlier results indicate that administration of exogenous recombinant HSP70 increases the survival of animals in the septic shock model and suppresses the activation of neutrophils and macrophages induced by the S form of LPS [6]. By now, the effect of S LPSs on myeloid cells has been studied in detail, but little is known about the action of R forms. Previously, we found an effect of various LPS chemotypes on ROS production and apoo ptosis in neutrophils [7]. Here, we studied the effect of exogenous HSP70 on ROS and TNFα production by macrophages exposed to various LPS chemotypes. We also studied the effect of exogenous HSP70 and LPSs on the TLR2 and TLR4 expression in macrophages. Earlier studies showed that administration of exogg enous HSP70 reduced …

The role of the TLR-dependent signaling pathway in the mechanism of phagocyte protection by exogenous heat shock protein HSP70 from the endotoxin action

305 Endotoxins play an important role in the developp ment of a Grammnegative sepsis, as well as in some diss eases, such as metabolic syndrome and coronary heart disease [1]. The effect of endotoxins (lipopolysacchaa rides, LPS) on the target cells is realized via Tollllike receptors 4 (TLR4) which they contain. Entering the bloodstream, LPS first interact with the LPSSbinding protein and then with CD14 receptors of the target cells (including blood phagocytes). Then, LPS pass from CD14 to MDD2 (lymphocyte antigen 96) with subsequent formation of two LPS–MDD2–TLR4 complexes, which further form a heterodimeric comm plex in the target cell membrane [2]. Signal transducc tion from this complex activates transcription factors (in particular, NFFκB, nuclear factor kappa B) and triggers the cell response, characteristic of which is an increase in adhesion factors and synthesis of proinn flammatory cytokines, TNFFα being the first to be synthesized [3]. In inflammatory diseases (in particular, sepsis), the synthesis and secretion of heat shock proteins (HSP70) are elevated, which plays an important role in the mechanism providing protection from heat shock and other types of stress. It is assumed that HSP70 can bind to TLRs [4]. Application of exogee nous recombinant HSP70 decreases the animal morr tality rate in the septic shock model, as well as inhibits endotoxinninduced activation of neutrophils and macrophages [5]. Study of the effects of HSP70 and LPS on TLR expression has yielded ambiguous results, suggesting both an increase and a decrease in TLR expression induced by HSP70 and LPS [6, 7]. The effect of intraa cellular HSP70 has been rather comprehensively studd ied; however, the mechanisms underlying the action of extracellular HSP70 are still unclear. We have studied the role of the TLRRdependent signaling pathway in the mechanism underlying the protection of blood phagocytes from endotoxins by the exogenous heat shock protein HSP70. We have earlier demonstrated that exogenous HSP70 protects innate immunity cells from endotoxins [5]; however, the mechanism of its protective action is unclear. Here, we have shown that HSP70 increases the numm ber of TLR2 and TLR4 on the cell membrane of neuu trophils and monocytes and insignificantly elevates TNFFα production by these cells predominantly with involvement of TLR44dependent signal transduction. On the other hand, exogenous HSP70 decreases the LPSSinduced increase in TLR2 and TLR4 expression in these cells. MATERIALS AND METHODS The following reagents were used in this study: E. The gene of recombinant human …

Exogenous heat shock protein HSP70 protects human blood phagocytes at the action of different chemotypes of lipopolysaccharide.

392 It is known that lipopolysaccharides (LPS) play the key role in the development of Gram negative sepsis. They also have important implications for develop ment of certain socially significant diseases [1]. The majority of the enterobacterium Escherichia coli have S form of LPS, which includes hydrophobic lipid A, an oligosaccharide core, and O antigen. In addition to the LPS S form, enterobacteria also synthetize core defect molecules of LPS (R chemotypes), which have lipid A and a core part of different lengths. Core defect structures are marked Rb–Re chemotypes; and structures that have a complete external core, Ra chemotype [2]. Entering blood stream, LPS first inter act with lipopolysaccharide binding protein (LBP), then with CD14 receptor of target cells. After that, LPS are transferred from CD14 to MD 2 (lymphocyte antigen 96), and subsequent formation of two com plexes LPS MD 2 TLR4 occurs; then, they form a heterodimer receptor complex in the membrane of target cells [3]. Then, a signal is transferred from the receptor to transcription factors in target cells, and the cell response is developed. At the early stages of cell response, reactive oxygen species (ROS) production, as well as adhesion factors expression, increase. In a later period, pro inflammatory cytokines are synthe tized, TNF α being the first of them to be secreted [4].

Heat-shock protein HSP70 decreases activity of proteasomes in human neuroblastoma cells treated by amyloid-beta 1-42 with isomerized Asp7

Experimental evidences indicate that heat-shock protein 70 (HSP70) can serve as a prospective therapeutic agent to treat Alzheimer’s disease (AD). It has demonstrated a neuroprotective effect in vivo on mice models of AD. Moreover, HSP70 decreases oxidative stress in neurons induced by amyloid-β (Aβ42) and its more toxic form with isomerized Asp7 (isoAβ42). The dysfunction of Ubiquitin-proteasome system (UPS) is observed in AD. UPS is responsible for the degradation of the majority of cellular proteins and plays an important role in protecting cells from oxidative stress. Here, we have shown that the incubation of human neuroblastoma cells SK-N-SH with isoAβ42 increases the activity of intracellular proteasomes, which are the principal elements of the UPS. On the contrary, the proteasomal activity was decreased in isoAβ42-treated cells in the presence of exogenous HSP70. These results highlight the existence of an interplay between Aβ peptides, proteasomes, and HSP70.