Synthesis Of Heat Shock Proteins Research Articles

Synthesis and approbation of new neuroprotective chemicals of pyrrolyl- and indolylazine classes in a cell model of Alzheimer's disease.

One of the major causes of neurodegeneration in the pathogenesis of Alzheimer's disease is the accumulation of cytotoxic amyloid species within the intercellular compartments of the brain. The efficacy of the anti-proteotoxic mechanism based on the molecular chaperones Hsp70 and Hsp90 in numerous types of neurons is often low, while its pharmacological enhancement has been shown to ameliorate the physiological and cognitive functions of the brain. Suggesting that the chemicals able to induce heat shock protein synthesis and therefore rescue neural cells from cytotoxicity associated with amyloid, we have synthesized a group of pyrrolyl- and indolylazines that cause the accumulation of heat shock proteins, using a novel method of photocatalysis that is employed in green chemistry. The selected compounds were tested in a cell model of Alzheimer's disease and demonstrated a pronounced neuroprotective effect. These substances increased the survival of neurons, blocked the activation of β-galactosidase, and prevented apoptosis in neurons cultured in the presence of β-amyloid.

Sunburn in Grapes: A Review.

Sunburn is a physiological disorder that affects the visual and organoleptic properties of grapes. The appearance of brown and necrotic spots severely affects the commercial value of the fruit, and in extreme cases, significantly decreases yield. Depending on the severity of the damage and the driving factors, sunburn on grapes can be classified as sunburn browning (SB) or as sunburn necrosis (SN). Sunburn results from a combination of excessive photosynthetically active radiation (PAR) and UV radiation and temperature that can be exacerbated by other stress factors such as water deficit. Fruit respond to these by activating antioxidant defense mechanisms, de novo synthesis of optical screening compounds and heat-shock proteins as well as through morphological adaptation. This review summarizes the current knowledge on sunburn in grapes and compares it with relevant literature on other fruits. It also discusses the different factors affecting the appearance and degree of sunburn, as well as the biochemical response of grapes to this phenomenon and different potential mitigation strategies. This review proposes further directions for research into sunburn in grapes.

INFLUENCE OF HIGH TEMPERATURES ON HEAT TOLERANCE AND SYNTHESIS OF HEAT SHOCK PROTEINS IN SPRING WHEAT AT THE INITIAL STAGES OF DEVELOPMENT

Пшеница одна из сельскохозяйственных культур, которая подвергается действию температурного стресса в течение онтогенеза и особенно чувствительна к действию стресса на начальных стадиях её развития. Высокие температуры ограничивают рост, развитие и продуктивность растений. Однако, растения могут адаптироваться к температурному стрессу и имеют адаптивные механизмы на клеточном и молекулярном уровнях. Одним из таких адаптивных механизмов является увеличение синтеза белков теплового шока (БТШ), функции которых очень важны и разнообразны.Целью данной работы было изучить влияние различных тепловых обработок (37 и 39 ºC в течение 1, 3, 6, 24 ч и 50 ºC в течение 1, 3, 5 ч) на теплоустойчивость проростков яровой пшеницы (Triticum aestivum L.) и синтез БТШ (101, 70, 60 и 16.9 кДа) в побегах 4-х суточных и листьях 8-ми суточных проростков.На основании полученных данных сделан вывод, что 4-х суточные и 8-ми суточные проростки яровой пшеницы характеризуются схожей реакцией на тепловой стресс при 50 ºC, однако 4-х суточные проростки более устойчивы в начальный период стрессового воздействия. Воздействие температурами 37 и 39 ºC подходят для адаптации яровой пшеницы на начальных стадиях её развития (4-х суточные и 8-ми суточные проростки). Эти температуры приводят к схожей тенденции в синтезе БТШ в побегах и листьях. В тоже время, содержание БТШ16.9 зависит от стадии развития пшеницы. В нормальных условиях был отмечен синтез БТШ16.9 в побегах, но не в листьях. Сделано заключение, что адаптация 8-ми суточных проростков более длительный процесс (6-24 ч воздействия 37 и 39 ºC) по сравнению с 4-х суточными проростками (3-6 ч воздействия 37 и 39 ºC).

Association HSP70with some physiological parameters in dairy goat under south Turkey conditions

Background: It has been demonstrated that the composition of HSP70 heat shock protein 70 is temperature correlated HSP70 effects is one as cellular thermometer in response to heat stress and other stimuli. Goat also possess anatomical and physiological characteristics that qualify for their wide ability to ecological adaptability, nevertheless, the productivity of the individual declines during thermal stress .the study in the issuance of this article accomplished to analyze the level of concentration of heat shock protein variance heat stress phenotypes in response to chronic heat stress. Ruslt: The investigation has been carried out in Alpin (brown colour), Saanen (Wightcolour), these breeds same age (1-2 year) and differ in size and production performance. The thermostress appreciation was at a temperature humidity index (THI) 80.8 during summer, 55.1 during winter and 70.1 during spring. Physiological parameters for thermal stress susceptibility was carried at by combining pulse rate (PR) (bpm), respiration rate (RR) (breath/min), body temperature (BT) °C, skin temperature (ST) °C and head temperature (HT). HSP70 level of concentrations were analyzed with ELISA, the gene expression pattern of HSP70 in different seasons indicated that the HSP70 for Saanen breed was 26.9, 18.3 and 14.1 during spring, summer and winter respectively. HSP70 for Alpine was 12.7, 13.7 and 14.7 in the spring, summer and winter respectively. Conclusion: The seasonal variation associated with changes of environmental variable, especially ambient temperature had great effects on physiological and cellular function of goats. Under adverse climatic conditions the body and skin temperature of goats increased due to the heat loading into the animal body. To maintain the homeothermy, goats increased their respiratory frequency to promote heat dissipation. Moreover, goats’ body develop a cellular pathway to cope thermal challenge. This later is expressed through the high synthesis of heat shock protein that was observed in this study. HSPs represents an important molecular indicator when assessing heat stress in goats.

Proteomics reveals sex-specific heat shock response of Baikal amphipod Eulimnogammarus cyaneus

The ancient Lake Baikal is the largest source of liquid freshwater on Earth and home to a unique fauna. Several hundred mostly cold-adapted endemic amphipod species inhabit Baikal, an ecosystem that is already being influenced by global change. In this study, we characterized the core proteome and heat stress-induced changes in a temperature-tolerant endemic amphipod, Eulimnogammarus cyaneus, using a proteogenomic approach (PRIDE dataset PXD013237) to unravel the molecular mechanisms of the observed adverse effects. As males were previously found to be much more tolerant to thermal stress, we placed special emphasis on differences between the sexes. For both sexes, we observed adaption of energy metabolism, cytoskeleton, lipid, and carbohydrate metabolism upon heat stress. In contrast, significant differences were determined in the molecular chaperone response. Females from the control conditions possessed significantly higher levels of heat shock proteins (HSP70, HSPb1, Hsc70-3), which, in contrast to males, were not further increased in response to heat stress. The inability of females to further increase heat shock protein synthesis in response to temperature stress may be due to sex-specific processes, such as egg production, requiring a large proportion of the available energy. As ovigerous females synthesize generally higher amounts of protein, they also need higher levels of molecular chaperones for the folding of these new proteins. Thus, the higher sensitivity of females to heat shock may be due to the lack of molecular chaperone molecules to counteract the heat-induced protein denaturation.

Pathogens Manipulating Tick Behavior-Through a Glass, Darkly.

Pathogens can manipulate the phenotypic traits of their hosts and vectors, maximizing their own fitness. Among the phenotypic traits that can be modified, manipulating vector behavior represents one of the most fascinating facets. How pathogens infection affects behavioral traits of key insect vectors has been extensively investigated. Major examples include Plasmodium, Leishmania and Trypanosoma spp. manipulating the behavior of mosquitoes, sand flies and kissing bugs, respectively. However, research on how pathogens can modify tick behavior is patchy. This review focuses on current knowledge about the behavioral changes triggered by Anaplasma, Borrelia, Babesia, Bartonella, Rickettsia and tick-borne encephalitis virus (TBEV) infection in tick vectors, analyzing their potential adaptive significance. As a general trend, being infected by Borrelia and TBEV boosts tick mobility (both questing and walking activity). Borrelia and Anaplasma infection magnifies Ixodes desiccation resistance, triggering physiological changes (Borrelia: higher fat reserves; Anaplasma: synthesis of heat shock proteins). Anaplasma infection also improves cold resistance in infected ticks through synthesis of an antifreeze glycoprotein. Being infected by Anaplasma, Borrelia and Babesia leads to increased tick survival. Borrelia, Babesia and Bartonella infection facilitates blood engorgement. In the last section, current challenges for future studies are outlined.

Heat Shock Proteins. Properties. Role in Adaptation. Methodological Approaches to Definition

The aim of this review article is to generalize and systematize literature data on the properties of heat shock proteins, as well as their role in adaptation processes and experimental methods of their investigation. The synthesis of heat shock proteins is a universal response to stress, which plays an important role in protecting cells from negative external impacts. Heat shock proteins participate in fundamental cellular processes. Altered expression of heat shock proteins can serve as an important diagnostic marker of cellular responses to damage.

The renal antioxidative effect of losartan involves heat shock protein 70 in proximal tubule cells.

Angiotensin II exerts a cardinal role in the pathogenesis of hypertension and renal injury via action of angiotensin II type 1 (AT1) receptors. Local renin-angiotensin system (RAS) activity is essential for the mechanisms mediating pathophysiological functions. Proximal tubular angiotensinogen and tubular AT1 receptors are augmented by intrarenal angiotensin II. Caveolin 1 plays an important role as a regulatory molecule for the compartmentalization of redox signaling events through angiotensin II-induced NADPH oxidase activation in the kidney. A role for the renin-angiotensin system in the development and/or maintenance of hypertension has been demonstrated in spontaneously hypertensive rats (SHRs). Many effects of angiotensin II are dependent on the AT1 stimulation of reactive oxygen species (ROS) production by NADPH oxidase. Angiotensin II upregulation stimulates oxidative stress in proximal tubules from SHR. The NADPH oxidase 4 (Nox4) is abundantly expressed in kidney proximal tubule cells. Induction of the stress response includes synthesis of heat shock protein 70, a molecular chaperone that has a critical role in the recovery of cells from stress and in cytoprotection, guarding cells from subsequent insults. HSP70 chaperones function in part by driving the molecular triage decision, which determines whether proteins enter the productive folding pathway or result in client substrate ubiquitination and proteasomal degradation. This review examines regulation of losartan-mediated antioxidative stress responses by the chaperone HSP70 in proximal tubule cells of spontaneously hypertensive rats.

Hyperthermia and protein homeostasis: Cytoprotection and cell death.

Protein homeostasis or proteostasis, the correct balance between production and degradation of proteins, is an essential pillar for proper cellular function. Among the several cellular mechanisms that disrupt homeostatic conditions in cancer cells, hyperthermia (HT) has shown promising anti-tumor effects. However, cancer cells are also capable of thermoresistance. Indeed, HT-induced protein denaturation and aggregation results in the up regulation of heat shock proteins, a group of molecular chaperones with cytoprotective and anti-apoptotic properties via stress-inducible transcription factor, heat shock factor 1(HSF1). Heat shock proteins assist in the refolding of misfolded proteins and aids in their elimination if they become irreversibly damaged by various stressors. Furthermore, HSF1 also initiates the unfolded protein response in the endoplasmic reticulum (ER) to assist in the protein folding capacity of ER and also promotes the translation of pro-survival proteins' mRNA such as activating transcription factor 4 (ATF 4). Moreover, HT associated induction of microRNAs is also involved in thermal resistance of cancer cells via up-regulation of anti-apoptotic Bcl-2 proteins and down regulation of pro-apoptotic Bax and caspase 3 activities. Another cellular protection in response to stressors is Autophagy, which is regulated by the Mammalian target of rapamycin (mTOR) protein. Kinase activity in mTOR phosphorylates HSF1 and promotes its nuclear translocation for heat shock protein synthesis. Over-expression of heat shock proteins are reported to up-regulate Beclin-1, an autophagy initiator. Moreover, HT-induced reactive oxygen species (ROS) generation is sensitized by transcription factor NF-E2 related factor 2 (Nrf2) and activates the cellular expression of antioxidants and autophagy gene. Furthermore, ROS also potentiates autophagy via activation of Beclin-1. Inhibition of thermotolerance can potentiate HT-induced apoptosis. Here, we outlined that heat stress alters cellular proteins which activates cellular homeostatic processes to promote cell survival and make cancer cells thermotolerant.

A long noncoding RNA acts as a post-transcriptional regulator of heat shock protein (HSP70) synthesis in the cold hardy Diamesa tonsa under heat shock.

Cold stenothermal insects living in glacier-fed streams are stressed by temperature variations resulting from glacial retreat during global warming. The molecular aspects of insect response to environmental stresses remain largely unexplored. The aim of this study was to expand our knowledge of how a cold stenothermal organism controls gene expression at the transcriptional, translational, and protein level under warming conditions. Using the chironomid Diamesa tonsa as target species and a combination of RACE, qPCR, polysomal profiling, western blotting, and bioinformatics techniques, we discovered a new molecular pathway leading to previously overlooked adaptive strategies to stress. We obtained and characterized the complete cDNA sequences of three heat shock inducible 70 (hsp70) and two members of heat-shock cognate 70 (hsc70). Strikingly, we showed that a novel pseudo-hsp70 gene encoding a putative long noncoding RNA (lncRNA) which is transcribed during thermal stress, acting as a ribosome sponge to provide post-transcriptional control of HSP70 protein levels. The expression of the pseudo-hsp70 gene and its function suggest the existence of a new and unexpected mechanism to cope with thermal stress: lowering the pace of protein production to save energy and optimize resources for recovery.

Effects of Acute Heat Stress on a Newly Established Chicken Hepatocyte-Nonparenchymal Cell Co-Culture Model.

Simple SummaryAmong many environmental stress factors, heat stress can intensely deteriorate animal health, welfare, and productivity in poultry farming. In the present study, a novel cell culture comprised of different liver cell types from chickens was established to serve as a model for studying the effects of acute heat stress. Short, 1 h heat exposure strongly affected liver cells by increasing metabolism, triggering oxidative stress, and decreasing the generation of certain mediatory molecules of the cellular stress response. However, these alterations were normalized after 2 h of heat stress, suggesting a fast adaptation of liver cells. The results of this study underline the impact of short-term heat stress as a potential harmful factor affecting liver function in chickens.Heat stress is one of the most important issues in broiler flocks impairing animal health and productivity. On a cellular level, excess heat exposure can trigger heat shock response acting for the restoration of cell homeostasis by several mechanisms, such as affecting heat shock protein synthesis, redox homeostasis and pro-inflammatory cytokine production. The major aim of this study was to establish a novel avian hepatocyte—nonparenchymal cell co-culture as a model for investigating the cellular effects of heat stress and its interaction with inflammation in chicken liver. Cell fractions were isolated by differential centrifugation from a freshly perfused chicken liver, and hepatocyte mono-cultures as well as hepatocyte–nonparenchymal cell co-cultures (with cell ratio 6:1, hepatocytes to nonparenchymal cells, mimicking a milder hepatic inflammation) were prepared. Isolated and cultured cells were characterized by flow cytometry and immunocytochemistry applying hepatocyte- and macrophage-specific antibodies. Confluent cell cultures were exposed to 43 °C temperature for 1 or 2 h, while controls were cultured at 38.5 °C. The metabolic activity, LDH enzyme activity, reactive oxygen species (H2O2) production, extracellular concentration of heat shock protein 70 (HSP70), and that of the pro-inflammatory cytokines interleukin (IL-)6 and IL-8 were assessed. Shorter heat stress applied for 1 h could strongly influence liver cell function by significantly increasing catabolic metabolism and extracellular H2O2 release, and by significantly decreasing HSP70, IL-6, and IL-8 production on both cell culture models. However, all these alterations were restored after 2 h heat exposure, indicating a fast recovery of liver cells. Hepatocyte mono-cultures and hepatocyte—nonparenchymal cell co-cultures responded to heat stress in a similar manner, but the higher metabolic rate of co-cultured cells may have contributed to a better capability of inflamed liver cells for accommodation to stress conditions. In conclusion, the established new primary cell culture models provide suitable tools for studying the hepatic inflammatory and stress response. The results of this study highlight the impact of short-term heat stress on the liver in chickens, underline the mediatory role of oxidative stress in acute stress response, and suggest a fast cellular adaptation potential in liver cells.

Novel polymorphism of HSP70 gene affected caprine physiological vital parameters

The synthesis of heat shock protein 70 (HSP70) is temperature-dependent and its response is considered as a cellular thermometer in response to thermal stress. The variation in HSP70 gene expression has been positively correlated with thermo-tolerance. Three different goat populations (Black Bengal, Ganjam and Raighar) which differ in body size, coat color and production performance were assessed for effect of thermal stress at different temperature humidity index (THI). The physiological vital parameters like rectal temperature (RT), skin temperature (ST), heart rate (HR) and respiration rate (RR) which are related to thermal stress susceptibility were recorded. The genetic variation of HSP70 gene in the three goat populations and its effect on physiological vital parameters related to thermal stress was assessed. A novel polymorphism (C241T) in the exonic region of HSP70 gene with significant (p < .05) statistical association with the physiological vital parameters like RT, ST and RR was identified indicating its role in thermo-tolerance. Highlights The HSP70 gene was found to be polymorphic in Indian goats. The non-synonymous nucleotide change (C241T) resulted change in amino acid Arginine 241 Cysteine in mature polypeptide which were not reported earlier. The constructed phylogenetic tree showed that Ganjam and Raighar goats are more close to each other.

CL-43, a New Inhibitor of HSF1 Activity, Inhibits Epithelial-Mesenchymal Transition of DLD1 Colon Cancer Cells

Colorectal cancer is highly metastatic. In a quarter of patients with tumors of this type, liver metastases are detected already at the time of diagnosis. Therefore, the search for drugs that can reduce the metastatic activity of cells is an important task. A tumor experiences constant stress, resulting in an increased activity of the transcription factor HSF1, which is able to trigger the synthesis of heat shock proteins. This increases the resistance of cancer cells to both stress and antitumor therapy. It has been shown recently that HSF1 plays a critical role in the process of the epithelial–mesenchymal transition (EMT) underling the formation of metastases. Here, we show that a new inhibitor of HSF1 activity, CL-43, is capable of suppressing EMT that is induced by TGFβ1. CL-43 significantly reduced the migration and proliferative potency of DLD1 cells treated with TGFβ1. Analysis of vimentin level showed that cell treatment with CL-43 cells reduced this EMT marker and returned the expression and localization of E-cadherin in the cells to the original pattern. These findings suggest that CL-43 has therapeutic potential for treatment of colorectal tumors.

Heat Shock Proteins Are Essential Components in Transformation and Tumor Progression: Cancer Cell Intrinsic Pathways and Beyond.

Heat shock protein (HSP) synthesis is switched on in a remarkably wide range of tumor cells, in both experimental animal systems and in human cancer, in which these proteins accumulate in high levels. In each case, elevated HSP concentrations bode ill for the patient, and are associated with a poor outlook in terms of survival in most cancer types. The significance of elevated HSPs is underpinned by their essential roles in mediating tumor cell intrinsic traits such as unscheduled cell division, escape from programmed cell death and senescence, de novo angiogenesis, and increased invasion and metastasis. An increased HSP expression thus seems essential for tumorigenesis. Perhaps of equal significance is the pronounced interplay between cancer cells and the tumor milieu, with essential roles for intracellular HSPs in the properties of the stromal cells, and their roles in programming malignant cells and in the release of HSPs from cancer cells to influence the behavior of the adjacent tumor and infiltrating the normal cells. These findings of a triple role for elevated HSP expression in tumorigenesis strongly support the targeting of HSPs in cancer, especially given the role of such stress proteins in resistance to conventional therapies.

The androgen receptor antagonist enzalutamide induces apoptosis, dysregulates the heat shock protein system, and diminishes the androgen receptor and estrogen receptor β1 expression in prostate cancer cells.

Enzalutamide's accepted mode of action is by targeting the androgen receptor's (AR) activity. In clinical practice, enzalutamide demonstrates a good benefit-risk profile for the treatment of advanced prostate cancer (PC), even after poor response to standard antihormonal treatment. However, since both, well-established antiandrogens and enzalutamide, target AR functionality, we hypothesized that additional unknown mechanisms might be responsible for enzalutamide's superior anticancer activity. In the current study, PC cells were incubated with enzalutamide and enzalutamide-dependent modulation of apoptotic mechanisms were assessed via Western blot analysis, TDT-mediated dUTP-biotin nick end-labeling assay, and nuclear morphology assay. Alterations of heat shock protein (HSP), AR, and estrogen receptor (ER) expression were examined by Western blot analysis. Enzalutamide attenuated the proliferation of PC cells in a time- and dose-dependent manner. In the presence of enzalutamide, apoptosis occurred which was shown by increased BAX expression, decreased Bcl-2 expression, nuclear pyknosis, and genomic DNA fragmentation. Moreover, enzalutamide inhibited the expression of HSPs primarily involved in steroid receptor stabilization and suppressed AR and ERβ1 expression. This study demonstrates for the first time that enzalutamide treatment of PC cells triggers varying molecular mechanisms resulting in antiproliferative effects of the drug. In addition to the well-characterized antagonistic inhibition of AR functionality, we have shown that enzalutamide also affects the intracellular synthesis of steroid receptor-associated HSPs, thereby diminishing the expression of AR and ERβ1 proteins and inducing apoptotic pathways. According to an indirect attenuation of HSP-associated factors such as steroid receptors, endometrial carcinoma, uterine leiomyosarcoma, and mamma carcinoma cells also demonstrated inhibited cell growth in the presence of enzalutamide. Our data, therefore, suggest that enzalutamide's high efficacy is at least partially independent of AR and p53 protein expression, which are frequently lost in advanced PC.

Triptolide inhibits migration and proliferation of fibroblasts from ileocolonic anastomosis of patients with Crohn's disease via regulating the miR‑16‑1/HSP70 pathway.

Anastomotic fibrosis is highly likely to lead to reoperation in Crohn's disease (CD) patients. Triptolide (TPL) is considered to have anti-inflammatory and antifibrotic effects in a variety of autoimmune diseases, including CD. The present study aimed to investigate the effects of TPL on fibroblasts from strictured ileocolonic anastomosis of patients with CD and its underlying mechanism. Primary fibroblasts were obtained from strictured anastomosis tissue (SAT) samples and matched anastomosis-adjacent normal tissue (NT) samples which were collected from 10 CD patients who underwent reoperation because of anastomotic stricture. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) was used to measure miR-16-1 and heat shock protein 70 (HSP70) levels. Western blotting was conducted to determine expression of HSP70, collagen I (Col-I), collagen III (Col-III) and α-smooth muscle actin (α-SMA) proteins. Agomir-16-1 and antagomir-16-1 were used to up and downregulate the expression of miR-16-1, respectively. Small interfering RNA (siRNA) was employed to inhibit the expression of HSP70. A wound healing assay was performed to measure the migration of fibroblasts. Cell proliferation was evaluated by MTT and 5-bromo-2-deoxyrudidine assays. Cell apoptosis was determined by caspase-3 activity and TUNEL assays. The results demonstrated that the levels of Col-I, Col-III and α-SMA were all significantly upregulated in SAT compared with NT. miR-16-1 levels in the SAT group were significantly compared with the NT group; conversely, the expression levels of HSP70 mRNA and protein in the SAT group were significantly lower compared with the NT group. Next, fibroblasts were treated with TPL to examine its effect on the miR-16-1/HSP70 pathway. The results demonstrated that the elevated expression of miR-16-1 in the SAT group was effectively inhibited by TPL treatment. Compared with the NT group, both the mRNA and protein levels of HSP70 were significantly downregulated in the SAT group cells, while TPL exhibited a strong promoting effect on HSP70 synthesis. Furthermore, upregulation of miR-16-1 reversed the effect of TPL on the miR-16-1/HSP70 pathway in fibroblasts from SAT. Overexpression of miR-16-1 significantly reversed the inhibitory effects of TPL treatment on migration, proliferation and extracellular matrix (ECM)-associated protein expression of fibroblasts from SAT. Finally, downregulation of miR-16-1 caused similar effects to the fibroblasts as the TPL treatment; however, the inhibitory effects on cell biological functions induced by antagomir-16-1 were all significantly reversed by HSP70 silencing. The present findings indicated that TPL may be a potential therapeutic option for postoperative anastomosis fibrosis of patients with CD. The miR-16-1/HSP70 pathway had a substantial role in the inhibitory effects of TPL on migration, proliferation and ECM synthesis rate of fibroblasts from strictured anastomosis tissues.

Voyaging around ClpB/Hsp100 proteins and plant heat tolerance

Temperature is one of the key physical parameters that fine tunes plant growth and development. However, above the optimal range, it can negatively affect the physiology of plants. Supraoptimal temperature brings incongruity in cellular proteostasis resulting in the build-up of insoluble toxic protein aggregates. To prevent protein misfolding and aggregation, cells deploy different strategies including synthesis of heat shock proteins (Hsp) belonging to different families, like small Hsps (sHsps), Hsp40, Hsp60, Hsp70. Once these aggregates are formed, their dissolution and recovery of the functional proteins occurs by the action of Caseinolytic Protease B (ClpB)/Hsp100, which are evolutionarily conserved in bacteria, fungi and plants. ClpB function during heat stress (HS) is important and appears indispensable, as mutant bacteria, yeast as well as plants lacking ClpB protein fail to survive HS. Genetic expression of ClpB proteins is modulated both by high temperature as well as developmental cues. Plant contains three isoforms of ClpB/Hsp100, one each localized to cytoplasm (ClpB-C), chloroplast (ClpB-P) and mitochondria (ClpB-M), against one in bacteria and two in yeast. Among these, ClpB-C protein in particular governs the thermotolerance response in plants. This review introduces plant ClpB proteins, summarizes the knowledge gained hitherto in ClpB biology, critically analyzes the recent findings and brings forth the areas requiring thrust in the upcoming research on ClpBs.

Invited Review: Adaptations of protein and amino acid metabolism to heat stress in dairy cows and other livestock species

ABSTRACT The reduction of productivity and efficiency of nutrient utilization in heat-stressed dairy cattle is mediated by physiological and molecular alterations. Heat stress impairs the digestive and absorptive capacity of the gastrointestinal tract, and this effect is independent of nutrient intake. The shift in blood flow away from the splanchnic tissues to the skin reduces nutrient delivery to the small intestine and increases mucosal cell damage. The translocation of individual AA and the availability of total and individual AA to peripheral tissues is impaired during heat stress. In addition, heat stress alters tissue-specific demands for individual AA, protein synthesis, and whole-body protein degradation. For example, heat stress and the associated systemic inflammatory response alters the use of AA in metabolic tissues, increasing their demand. Glutamate, Gln, Arg, and Leu appear to ameliorate the inflammatory state of the intestine by preventing villi atrophy and improving synthesis of tight junction proteins and the intestinal barrier function. Moreover, heat stress increases the synthesis of acute phase proteins and heat-shock proteins and appears to promote hepatic removal of individual AA to sustain augmented protein synthesis. The fractional rates of extraction of total AA that reach the liver increase during systemic inflammation. An increase in intestinal and hepatic utilization of AA alters the net supply and the pattern of AA available to peripheral tissue. Whole-body protein breakdown and synthesis of urea increases in heat-stressed animals. This result suggests that AA are mobilized to meet the animal needs. Finally, local effects of heat stress may impair the synthesis of proteins in the mammary glands and reduce α-S2 casein and whey fractions, milk protein content, and milk protein yield, probably via reduced signaling activity. Collectively, heat stress alters the use of AA in absorptive and postabsorptive tissues, reducing AA availability to sustain animal production.

Heavy metal stress and responses in plants

Heavy metals such as Fe, Mn, Cu, Ni, Co, Cd, Zn, Hg and arsenic are for long being accumulated in soils through industrial waste and sewage disposal. Although some of these metals are essential micronutrients responsible for many regular processes in plants, their excess, however, can have detrimental effects and can directly influence the plant growth, metabolism, physiology and senescence. Plants have different mechanisms to fight stress, and they are responsible to maintain homeostasis of essential metals required by plants. These mechanisms also focus on prevention of plants exposure to heavy metals present in the soil or providing tolerance to the plant by detoxifying the metals. Other mechanisms are specific and are initiated when the respective stress is encountered. The first line of defense provided by a plant is to reduce the uptake of metals when stimulated with toxicity of heavy metals and includes the help offered by cellular and root exudates that restricts metals from entering the cell. Many plants have exclusive mechanisms for individual metal ions and are involved in sequestering these ions in compartments avoiding their exposure to sensitive components of the cells. As a second line of defense, other mechanisms for detoxification of these metals are introduced that chelates, transports, sequesters and detoxifies these metal ions in the plant’s vacuole. During the time of metal toxicity, oxidative stress is pronounced in the cells and production of stress-related proteins and hormones, antioxidants, signaling molecules including heat-shock proteins synthesis is initiated.

Heat-Shock Protein 70-Mediated Heat Preconditioning Attenuates Hepatic Carbohydrate and Oxidative Disturbances in Rats With Type 1 Diabetes.

Heat preconditioning and heat-shock protein (HSP) synthesis have significant cytoprotective effects against the development of cellular injury caused by the application of a subsequent stressor, which were found to depend on the time period between the stressors. We aimed to determine the most efficient recovery time (6h or 24h) following heat-stress exposure and prior application of diabetic streptozotocin (STZ) on the moderation of carbohydrate and oxidative metabolic disturbances caused by diabetes. Experiment animals (Wistar rats) were exposed to acute heat stress at 41±1°C for 45min, followed by 6-h or 24-h recovery times at room temperature before sacrifice or STZ administration. Our findings indicate that acute heat stress with 6-h or 24-h recovery periods results in a significant rise in the hepatic heat-shock protein 70 (HSP70) levels (even more so after 24h), glycogen breakdown and stable glycemia, followed by reduced glycolytic and gluconeogenic activity (after 24h) (glucose-6-phosphatase, fructose-1,6-bisphosphatase); stimulates antioxidative activity (glutathione peroxidase, glutathione reductase) (after 6h); and decreases glutathione and catalase activity (after 24h). Heat preconditioning (with 6-h and 24-h recovery periods) prior to STZ-induced diabetes increases HSP70 levels and causes lower serum glucose levels, higher glycogen and glucose-6-phosphate levels, lower glucose-6-phosphatase levels and glycogen phosphorylase and hexokinase levels but also elevates glutathione reductase and glutathione peroxidase activity compared to untreated STZ animals. Based on our findings, heat preconditioning and HSP70 induction in rats with type 1 diabetes attenuates STZ-induced metabolic alterations in hepatic carbohydrate metabolism and oxidative states. These changes are more evident at 24h recovery post-acute heat stress, based on the most evident accumulation of HSP70 in this time frame.