Non-lethal Heat Shock Research Articles

Molecular mechanisms of induced thermotolerance in two strains of Brachionus koreanus (Rotifera: Monogononta)

Temperature plays an important role in the occurrence and performance of organisms in aquatic ecosystems and is also one of the main environmental factors affecting species' survival and growth in aquaculture. As an important species for aquaculture sustainability, the rotifer Brachionus sp. benefits from inducible phenotypic traits that allow the organisms to cope with environmental stress. The exposure to high temperature has shown to increase production of heat shock proteins (HSPs) and histone modifications in several organisms, resulting in induced thermotolerance. This study aimed to evaluate the potential of non-lethal heat shock (NLHS) to induce thermotolerance in two strains of B. koreanus and pinpoint some of the molecular mechanisms involved in the process. Exposure of organisms to 42 °C for 30 min, with a subsequent recovery at 25 °C for 8 h demonstrated to increase thermotolerance in up to three-fold when organisms were, in a posterior phase, subjected to a lethal temperature. This study also showed that one of the strains is tendentially more thermotolerant than the other. Indeed, NLHS exposure resulted in increased mRNA expression of different Hsp genes and production of HSP70 in general, but different patterns of expression were observed between strains. However, a single NLHS showed to have no effects in epigenetic mechanisms, suggesting that the induced capacity to tolerate heat stress was transient and some more cycles of NLHS may be needed to promote a persistent effect.

Prolonged ecological changes can affect morphometrics and gene expression profile? Focusing on Hsp-70 and NLHS-induced Hsp-70 of Artemia urmiana

BackgroundIn recent years, many aquatic ecosystems, including Urmia Lake, have undergone severe ecological tensions. This lake, the largest natural habitat of the brine shrimp Artemia urmiana, has progressively desiccated and its salinity has dramatically increased over the last three decades. In the face of the long period environmental stresses, understanding the adaptation and ecological plasticity mechanisms is the most interesting challenges in genetic and applied ecology. These mechanisms may probably be driven by inducing expression of some genes involved in adaptation such as Hsp-70 and also adjusting morphological parameters. But they are yet to be understood. Hence, the present work aimed to study the mechanisms, along with testing the hypothesis that non-lethal heat shocked nauplii originating from drought period can evoke Hsp-70 expression more than those from rainy period. MethodsThis study measured and analyzed morphometrical characters of adult male and female Artemia urmiana over three decades. Then, the influence of three-decade ecological crisis on Hsp-70 and non-lethal heat shock (NLHS)-induced Hsp-70 expression levels of nauplii of Artemia urmiana habiting Urmia Lake using Real-time PCR technique, based on cyst collections in 1994 (rainy period) to 2020 (drought period), was evaluated. ResultsThe morphometrics results showed that the morphological characters were significantly shrunk in 2020 compared to 1994 (CI 95%, p < 0.05). Furthermore, our results depicted that, Hsp-70 expression level was significantly upregulated in response to the prolonged ecological crisis, (CI 95%, P < 0.0001), and also interestingly, the nauplii exposed to longe-term ecological crisis (belong to 2020) were able to increase Hsp-70 expression more than other ones in response to environmental stressors including heat. ConclusionsThe present results showed the involvement of Hsp-70 in the adaptation of Artemia urmiana to long term ecological alteration at the cost of shrinking morphometric parameters.

The effects of non-lethal heat-shock-induced cross-protection on survival and growth of Pacific whiteleg shrimp, Litopenaeus vannamei in response to ionic stress in inland saline waters

Non-lethal heat shock (NLHS) was used to enhance tolerance to other stressors in aquatic organisms and its effects are associated with the accumulation of Hsp 70. A study was conducted to determine the effect of NLHS on the cross-protection of L. vannamei against stress in K+-deficient inland saline water. To determine the NLHS based on mortality and gill heat shock protein 70 (Hsp70) abundance, L. vannamei juveniles (3.52 ± 0.23 g) were reared in inland water of 10 ppt salinity with 100% seawater equivalent (SWequ) K+ fortification. As one hour of heat shock at 36 °C resulted no mortality and a 3.5-fold increase in Hsp70 protein in gills when followed by 8 h recovery at 28 °C, the 36 °C was designated as NLHS. Subsequently, P. vannamei juveniles (4.64 ± 0.01 g) were exposed to 1 h NLHS in inland saline water containing 25%, 50% and 75% of SWequ K+ in triplicates following a recovery of 8 h, whereas the control group did not receive NLHS. The NLHS significantly increased Hsp70 protein in the gills and muscle. In addition, NHLS brought about higher catalase and superoxide dismutase activity in the gills and hepatopancreas, along with increased serum glucose levels. Increased Hsp70 protein abundance in muscle and gills remained elevated even after 12 h exposure to varying K+ levels, conferring cross-protection by NLHS against ionic stress caused by K+ depletion in inland saline waters. A 45-day growth study showed a significant increase in weight gain and survival (%) in NLHS groups compared to the control group, irrespective of the K+ fortification. This growth-promoting effect of NLHS was also evident in the group reared in the most K+ deficient inland saline water. This study shows that NLHS provides cross-protection through accumulation of Hsp70 protein and activation of antioxidant enzymes, in K+ deficient inland saline water, promoting shrimp growth and survival with atleast 50 aqueous K+ supplementation.

Prx4 acts as DAMP in shrimp, enhancing bacterial resistance via the toll pathway and prophenoloxidase activation

Peroxiredoxin (Prx), an antioxidant enzyme family, has been identified as immune modulating damage-associated molecular patterns (DAMPs) in mammals but not in shrimp. Acute non-lethal heat shock (NLHS) that enhances shrimp Penaeus vannamei resistance to Vibrio parahaemolyticus causing acute hepatopancreatic necrosis disease (VPAHPND). Among the five P.vannamei Prxs (LvPrx) isoforms, LvPrx4, the most abundant in unchallenged shrimp hemocytes that was upregulated in hemocytes following NLHS treatment, is of great interest. The escalation of the LvPrx4 monomer in hemolymph of NLHS treated shrimp indicates that it probably acts as DAMP. This study revealed that pre-challenge with rLvPrx4 could prolong VPAHPND-infected shrimp survival, increase prophenoloxidase (proPO) activity and promote Toll pathway-related genes expression mediated by Toll-like receptor (TLR) 1 and 2. The presented findings elucidated the molecular mechanism of LvPrx4 monomer as DAMP in NLHS-induced VPAHPND resistance by inducing the TLR1/2 signaling pathway and the proPO activating system.

Heat Shock Proteins (Hsps) in Cellular Homeostasis: A Promising Tool for Health Management in Crustacean Aquaculture.

Heat shock proteins (Hsps) are a family of ubiquitously expressed stress proteins and extrinsic chaperones that are required for viability and cell growth in all living organisms. These proteins are highly conserved and produced in all cellular organisms when exposed to stress. Hsps play a significant role in protein synthesis and homeostasis, as well as in the maintenance of overall health in crustaceans against various internal and external environmental stresses. Recent reports have suggested that enhancing in vivo Hsp levels via non-lethal heat shock, exogenous Hsps, or plant-based compounds, could be a promising strategy used to develop protective immunity in crustaceans against both abiotic and biotic stresses. Hence, Hsps as the agent of being an immune booster and increasing disease resistance will present a significant advancement in reducing stressful conditions in the aquaculture system.

Effects of heat shock protein 70 knockdown on the tolerance of the brine shrimp Artemia franciscana to aquaculture-related stressors: Implications for aquatic animal health and production

Temperature, pH, salinity and ammonia stress adversely affect the performance and well-being of aquatic organisms, especially those used in aquaculture, a major food production sector. Management strategy to mitigate stress caused by abiotic factors in farmed aquatic organisms is scarce but is highly warranted considering the negative impact of these factors on the welfare and economic production of the farmed animals. The induction of heat shock proteins, mainly 70 kDa Hsp (Hsp70), in farmed fish and shellfish, including the live feed brine shrimp Artemia franciscana, by exposure to a non-lethal heat shock (NLHS) of 37 °C for 30 min followed by 6 h recovery period caused a significant improvement in the tolerance of the animals towards subsequent challenge with an abiotic stress. Although the protective effect of NLHS was associated with enhanced Hsp70 accumulation in these species, the induction of other members of Hsp and their collective involvement in the stress tolerance could not be ignored. This triggered an argument as to whether only Hsp70 or its combination with other Hsps was responsible for inducing stress tolerance phenotype in these species. In this study, we employed RNAi technology in the biological model organism Artemia to gain insight into the functional role of Hsp70 in stress tolerance. The results showed that upon exposure to a NLHS, the wild-type Artemia nauplii capable of producing Hsp70 exhibited significantly higher survival than the unexposed control in all the abiotic stress tolerance tests performed in this study. However, the Hsp70-deficient mutant nauplii did not exhibit increased stress-tolerant phenotypes as the survival percentage of the nauplii decreased by 29, 19, and 15%, respectively, upon challenge with a median lethal concentration of salinity, pH, and ammonia. These results suggest that Hsp70 was involved in inducing tolerance against stress caused by the abiotic factors, and hence can be a potential target for developing strategies to protect economically important aquaculture species from environmental disturbances.

Non-lethal heat shock and Probiotic enhance immune system in larvae P. Vannamei

Non-lethal heat shock and Probiotic enhance immune system in larvae P. Vannamei

Short-term heat shock perturbation affects populations of Daphnia magna and Eurytemora carolleeae: a warning to the water thermal pollution

Thermal pollution leads to short-term heat shock in aquatic invertebrates; however, the modulation of tolerance and life history of these invertebrates by thermal stress varies among regions, phenology, species, and their acclimation. To assess the effect of thermal shock, we conducted experiments on Daphnia magna and Eurytemora carolleeae at 25 °C, 30 °C, 35 °C, and 40 °C (in relation to 20 °C) in a different exposure time of the stressor (10, 30, and 60 min). The results showed that short-term heat shock leads to increased mortality and reduced fertility of the studied planktonic crustaceans. D. magna was more resistant to thermal shock than E. carolleeae according to all variants of exposure based on the calculated LT50 values for 24, 48, and 72 h. Thermal shock decreased the potential of the Daphnia population in terms of the total number of births, however, with regard to individual reproductive abilities, the non-lethal heat shock did not reduce the birth rate. Although Eurytemora is more sensitive to thermal shock than Daphnia, the type of parental care in Eurytemora might be more favorable for offspring survival following thermal shock than in Daphnia. In Eurytemora, despite maternal deaths, a relatively high number of newborns who survived high temperatures were observed. The obtained results can help to understand the ecological processes occurring due to anthropogenic thermal pollution.

An Experimental Test of Adaptive Introgression in Locally Adapted Populations of Splash Pool Copepods.

As species struggle to keep pace with the rapidly warming climate, adaptive introgression of beneficial alleles from closely related species or populations provides a possible avenue for rapid adaptation. We investigate the potential for adaptive introgression in the copepod, Tigriopus californicus, by hybridizing two populations with divergent heat tolerance limits. We subjected hybrids to strong heat selection for 15 generations followed by whole-genome resequencing. Utilizing a hybridize evolve and resequence (HER) technique, we can identify loci responding to heat selection via a change in allele frequency. We successfully increased the heat tolerance (measured as LT50) in selected lines, which was coupled with higher frequencies of alleles from the southern (heat tolerant) population. These repeatable changes in allele frequencies occurred on all 12 chromosomes across all independent selected lines, providing evidence that heat tolerance is polygenic. These loci contained genes with lower protein-coding sequence divergence than the genome-wide average, indicating that these loci are highly conserved between the two populations. In addition, these loci were enriched in genes that changed expression patterns between selected and control lines in response to a nonlethal heat shock. Therefore, we hypothesize that the mechanism of heat tolerance divergence is explained by differential gene expression of highly conserved genes. The HER approach offers a unique solution to identifying genetic variants contributing to polygenic traits, especially variants that might be missed through other population genomic approaches.

The cellular heat shock response monitored by chemical exchange saturation transfer MRI

CEST-MRI of the rNOE signal has been demonstrated in vitro to be closely linked to the protein conformational state. As the detectability of denaturation and aggregation processes on a physiologically relevant scale in living organisms has yet to be verified, the aim of this study was to perform heat-shock experiments with living cells to monitor the cellular heat-shock response of the rNOE CEST signal. Cancer cells (HepG2) were dynamically investigated after a mild, non-lethal heat-shock of 42 °C for 20 min using an MR-compatible bioreactor system at 9.4 T. Reliable and fast high-resolution CEST imaging was realized by a relaxation-compensated 2-point contrast metric. After the heat-shock, a substantial decrease of the rNOE CEST signal by 8.0 ± 0.4% followed by a steady signal recovery within a time of 99.1 ± 1.3 min was observed in two independent trials. This continuous signal recovery is in coherence with chaperone-induced refolding of heat-shock induced protein aggregates. We demonstrated that protein denaturation processes influence the CEST-MRI signal on a physiologically relevant scale. Thus, the protein folding state is, along with concentration changes, a relevant physiological parameter for the interpretation of CEST signal changes in diseases that are associated with pathological changes in protein expression, like cancer and neurodegenerative diseases.

Antibacterial and antiproteinase activities of a double whey acidic protein domain-containing protein from Penaeus vannamei Boone, 1931 (Decapoda, Penaeidae)

Abstract Double whey acidic protein domain-containing proteins (DWDs) or secretory leukocyte protease inhibitor (SLPI)-like proteins, have been identified in many species of Crustacea. The PvDWD1 from Penaeus vannamei was the first SLPI-like protein identified in a crustacean. Herein, we report that the expression of PvDWD1 was up-regulated at 6 h after acute hepatopancreatic necrosis disease (AHPND)-causing Vibrio parahaemolyticus (VPAHPND) challenge. Similarly, after a different stress other than bacterial infection, the chronic non-lethal heat shock (NLHS) induction, the expression of the PvDWD1 gene was increased at 6 and 24 h after chronic NLHS treatment. The recombinant PvDWD1 (rPvDWD1) protein was over-expressed and tested for its deleterious activity against the bacteria. The rPvDWD1 protein exhibited growth inhibitory activity against Bacillus megaterium and VPAHPND. Moreover, the rPvDWD1 protein possessed an antiproteinase activity against the secreted proteinases from Bacillus subtilis and VPAHPND. The PvDWD1 perhaps functions in shrimp immunity through antimicrobial and antiproteinase properties.

Sequence and expression analysis of HSP70 family genes in Artemia franciscana

Thus far, only one gene from the heat shock protein 70 (HSP70) family has been identified in Artemia franciscana. Here, we used the draft Artemia transcriptome database to search for other genes in the HSP70 family. Four novel HSP70 genes were identified and designated heat shock cognate 70 (HSC70), heat shock 70 kDa cognate 5 (HSC70-5), Immunoglobulin heavy-chain binding protein (BIP), and hypoxia up-regulated protein 1 (HYOU1). For each of these genes, we obtained nucleotide and deduced amino acid sequences, and reconstructed a phylogenetic tree. Expression analysis revealed that in the juvenile state, the transcription of HSP70 and HSC70 was significantly (P < 0.05) higher in a population of A. franciscana selectively bred for increased induced thermotolerance (TF12) relative to a control population (CF12). Following non-lethal heat shock treatment at the nauplius stage, transcription of HSP70, HSC70, and HSC70-5 were significantly (P < 0.05) up-regulated in TF12. In contrast, transcription of the other HSP70 family members in A. franciscana (BIP, HYOU1, and HSPA4) showed no significant (P > 0.05) induction. Gene expression analysis demonstrated that not all members of the HSP70 family are involved in the response to heat stress and selection and that especially altered expression of HSC70 plays a role in a population selected for increased thermotolerance.

Involvement of Stat3 phosphorylation in mild heat shock-induced thermotolerance

Thermotolerance is a phenomenon in which cells become resistant to stress by prior exposure to heat shock, and its development is associated with the induction of heat shock proteins (Hsps), including Hsp70. We previously showed that the expression of Hsp70 is regulated by the cytokine signaling transcription factor Stat3, but the role of Stat3 in thermotolerance is not known. In this study, we examined the possible involvement of Stat3 in the acquisition of thermotolerance. We found that severe heat shock-induced morphological changes and decreases in cell viability, which were suppressed by exposure to non-lethal mild heat shock prior to severe heat shock. This thermotolerance development was accompanied by Stat3 phosphorylation and the induction of Hsps such as Hsp105, Hsp70, and Hsp27. Stat3 phosphorylation and Hsp induction were inhibited by AG490, an inhibitor of JAK tyrosine kinase. Consistent with this, we found that mild heat shock-induced thermotolerance was partially suppressed by AG490 or knockdown of Hsp105. We also found that the Stat3 inhibitor Stattic suppresses the acquisition of thermotolerance by inhibiting the mild heat shock-induced Stat3 phosphorylation and Hsp105 expression. These results suggest that the mild heat shock-dependent stimulation of the JAK-Stat signaling pathway contributes to the development of thermotolerance via the induction of Hsps including Hsp105. This signaling pathway may be a useful target for hyperthermia cancer therapy.

Litopenaeus vannamei heat shock protein 70 (LvHSP70) enhances resistance to a strain of Vibrio parahaemolyticus, which can cause acute hepatopancreatic necrosis disease (AHPND), by activating shrimp immunity

Heat shock protein 70 (HSP70) acts as a molecular chaperone and a stress protein, but also plays important roles in innate and adaptive immune responses. Previous studies have reported that non-lethal heat shock (NLHS) could enhance the resistance of Pacific white shrimp Litopenaeus vannamei to a specific strain of Vibrio parahaemolyticus, which carried a toxin-producing plasmid (VPAHPND), via the induction of LvHSP70 transcription. Here, we further investigated the specific function of LvHSP70 in shrimp immunity. The upregulation of LvHSP70 at the protein level was detected during recovery time after NLHS treatment, using both western blot analysis and immunofluorescence microscopy. We found that NLHS immediately activated the production of LvHSP70 in shrimp hemocytes and that such induction was observed in all three types of hemocytes: hyaline; granular and semi-granular cells. Furthermore, the role of LvHSP70 in bacterial defense was investigated using the heterologous expression of recombinant LvHSP70 (rLvHSP70) in Escherichia coli. Shrimp receiving rLvHSP70 by injection showed an increased survival rate (75%) to VPAHPND infection compared to just 20% survival in the control group injected with bovine serum albumin (BSA). We also demonstrated that the injected rLvHSP70 accumulated in shrimp hemocytes and was detected in the intracellular space of hemocyte cells leading to the induced expression (P<0.05) of several immune-related genes (LvMyD88, LvIKKβ, LvIKKε, LvCrustin I, LvPEN2, LvPEN3, LvproPO1, LvproPO2 and LvTG1). Collectively, these results suggest that LvHSP70 plays a crucial role in bacterial defense by activating the shrimp immune system.

Non-lethal heat shock induces Hsp70 synthesis and promotes tolerance against heat, ammonia and metals in post-larvae of the white leg shrimp Penaeus vannamei (Boone, 1931)

Exposure to temperatures above ambient compromises normal physiological processes and adversely affects aquatic organisms. Nonetheless, non-lethal heat shock (NLHS) protects aquatic organisms against abiotic and biotic stress, perhaps due in part to the accumulation of heat shock protein 70 (Hsp70), a well conserved molecular chaperone. Hsp70 protects cells against stress-induced damage by assisting in the recovery of misfolded proteins, facilitating the folding of nascent proteins and promoting protein degradation. In this study, the immunoprobing of western blots containing protein extracts from the caudal muscle of heated and non-heated post-larvae (PL) of the shrimp, Penaeus vannamei with an antibody specific to Hsp70 revealed that NLHS enhanced Hsp70 build-up in the caudal tissues of shrimp PL. Moreover, exposure to NLHS protected P. vannamei PL against heat, ammonia and heavy metals. The findings in this paper indicate that Hsp70 synthesized in response to NLHS contributed to the protection of P. vannamei PL against several different abiotic stressors. Such findings are potentially useful in the formulation of strategies to protect Penaeid shrimps against environmental stresses during aquaculture.

Systematic identification and characterization of stress-inducible heat shock proteins (HSPs) in the salmon louse (Lepeophtheirus salmonis).

Salmon lice (Lepeophtheirus salmonis) are parasitic copepods, living mainly on Atlantic salmon and leading to large economical losses in aquaculture every year. Due to the emergence of resistances to several drugs, alternative treatments are developed, including treatment with hydrogen peroxide, freshwater or thermal treatment. The present study gives a first overview of the thermotolerance and stress response of salmon lice. Sea lice nauplii acclimated to 10°C can survive heat shocks up to 30°C and are capable of hardening by a sublethal heat shock. We searched in the genome for heat shock protein (HSP) encoding genes and tested their inducibility after heat shock, changes in salinity and treatment with hydrogen peroxide, employing microfluidic qPCRs. We assessed 38 candidate genes, belonging to the small HSP, HSP40, HSP70 and HSP90 families. Nine of these genes showed strong induction after a non-lethal heat shock. In contrast, only three and two of these genes were induced after changes in salinity and incubation in hydrogen peroxide, respectively. This work provides the basis for further work on the stress response on the economically important parasite L. salmonis.

HSP70 and HSP90 are involved in shrimp Penaeus vannamei tolerance to AHPND-causing strain of Vibrio parahaemolyticus after non-lethal heat shock

Acute hepatopancreatic necrosis disease (AHPND) caused by Vibrio parahaemolyticus carrying toxin-producing plasmid, has led to severe mortalities in farmed penaeid shrimp throughout Asia. Previous studies reported that a non-lethal heat shock (NLHS) could enhance disease tolerance in aquatic animals. Here, we investigate whether the NLHS could enhance the survival of shrimp Penaeusvannamei upon challenge with an AHPND-causing strain of V. Parahaemolyticus (VPAHPND). Two NLHS conditions, acute and chronic NLHSs, were used. The former abruptly exposed the juveniles shrimp from 28 °C to 38 °C for 30 min only once whereas the latter exposed the shrimp to 38 °C for 5 min every day for 7 days. The treated shrimp were, then, challenged with VPAHPND at day 3, day 7, and day 30 during the recovery time after the treatment. The results showed that the shrimp exposed to either acute or chronic NLHS had higher survival rate (>50%) than that of the non-heated shrimp control (20%) when they were challenged with VPAHPND at day 3 recovery time. However, only those exposed to chronic NLHS showed the VPAHPND protection at day 7 and day 30 recovery times. Furthermore, the qRT-PCR analysis revealed that the expression of heat shock proteins, LvHSP70, LvHSP90 as well as other immune-related genes, LvproPO and LvCrustin, were induced upon exposure of shrimp to chronic NLHS. Interestingly, gene silencing of LvHSP70 and LvHSP90 eliminated the VPAHPND tolerance in the chronic NLHS shrimp and had decreasing PO activity suggesting that these LvHSPs played crucial roles in bacterial defense in shrimp. All together, we show for the first time that the NLHS enhance the shrimp tolerance to VPAHPND infection and this is likely mediated by the induction of LvHSP70, LvHSP90 and subsequent activation of the proPO system.

Non-lethal heat shock increases tolerance to metal exposure in brine shrimp

Pollution and temperature increase are two of the most important stressors that aquatic organisms are facing. Exposure to elevated temperatures and metal contamination both induce heat shock proteins (HSPs), which may thus be involved in the induced cross-tolerance in various organisms. This study aimed to test the hypothesis that exposure to a non-lethal heat shock (NLHS) causes an increased tolerance to subsequent metal exposure. Using gnotobiotic cultures of the brine shrimp Artemia franciscana, the tolerance to Cd and Zn acute exposures was tested after a prior NLHS treatment (30min exposure to 37°C). The effects of NLHS and metal exposure were also assessed by measuring 70kDa-HSPs production, along with the analysis of epigenetic markers such as DNA methylation and histone H3 and histone H4 acetylation. Our results showed that heat-shocked Artemia had increased acute tolerance to Cd and Zn. However, different patterns of HSPs were observed between the two metal compounds and no epigenetic alterations were observed in response to heat shock or metal exposure. These results suggest that HSP production is a phenotypically plastic trait with a potential role in temperature-induced tolerance to metal exposure.

Heritable variation in heat shock gene expression: a potential mechanism for adaptation to thermal stress in embryos of sea turtles.

The capacity of species to respond adaptively to warming temperatures will be key to their survival in the Anthropocene. The embryos of egg-laying species such as sea turtles have limited behavioural means for avoiding high nest temperatures, and responses at the physiological level may be critical to coping with predicted global temperature increases. Using the loggerhead sea turtle (Caretta caretta) as a model, we used quantitative PCR to characterise variation in the expression response of heat-shock genes (hsp60, hsp70 and hsp90; molecular chaperones involved in cellular stress response) to an acute non-lethal heat shock. We show significant variation in gene expression at the clutch and population levels for some, but not all hsp genes. Using pedigree information, we estimated heritabilities of the expression response of hsp genes to heat shock and demonstrated both maternal and additive genetic effects. This is the first evidence that the heat-shock response is heritable in sea turtles and operates at the embryonic stage in any reptile. The presence of heritable variation in the expression of key thermotolerance genes is necessary for sea turtles to adapt at a molecular level to warming incubation environments.

Tumor Therapeutics Work as Stress Inducers to Enhance Tumor Sensitivity to Natural Killer (NK) Cell Cytolysis by Up-regulating NKp30 Ligand B7-H6

Immune cells are believed to participate in initiating anti-tumor effects during regular tumor therapy such as chemotherapy, radiation, hyperthermia, and cytokine injection. One of the mechanisms underlying this process is the expression of so-called stress-inducible immunostimulating ligands. Although the activating receptor NKG2D has been proven to play roles in tumor therapy through targeting its ligands, the role of NKp30, another key activating receptor, is seldom addressed. In this study, we found that the NKp30 ligand B7-H6 was widely expressed in tumor cells and closely correlated to their susceptibility to NK cell lysis. Further studies showed that treatment of tumor cells with almost all standard tumor therapeutics, including chemotherapy (cisplatin, 5-fluorouracil), radiation therapy, non-lethal heat shock, and cytokine therapy (TNF-α), could up-regulate the expression of B7-H6 in tumor cells and enhance tumor sensitivity to NK cell cytolysis. B7-H6 shRNA treatment effectively dampened sensitization of tumor cells to NK-mediated lysis. Our study not only reveals the possibility that tumor therapeutics work as stress inducers to enhance tumor sensitivity to NK cell cytolysis but also suggests that B7-H6 could be a potential target for tumor therapy in the future.