Evolutionary diversity of vertebrate small heat shock proteins

Genome-Wide Identification, Molecular Characterization, and Expression Analysis of the HSP70 and HSP90 Gene Families in Thamnaconus septentrionalis

Heat shock proteins (HSPs) are a class of highly conserved proteins that play an important role in biological responses to various environmental stresses. The mariculture of Thamnaconus septentrionalis, a burgeoning aquaculture species in China, frequently encounters stressors such as extreme temperatures, salinity variations, and elevated ammonia levels. However, systematic identification and analysis of the HSP70 and HSP90 gene families in T. septentrionalis remain unexplored. This study conducted the first genome-wide identification of 12 HSP70 and 4 HSP90 genes in T. septentrionalis, followed by a comprehensive analysis including phylogenetics, gene structure, conserved domains, chromosomal localization, and expression profiling. Expression analysis from RNA-seq data across various tissues and developmental stages revealed predominant expression in muscle, spleen, and liver, with the highest expression found during the tailbud stage, followed by the gastrula, neurula, and juvenile stages. Under abiotic stress, most HSP70 and HSP90 genes were upregulated in response to high temperature, high salinity, and low salinity, notably hspa5 during thermal stress, hspa14 in high salinity, and hsp90ab1 under low salinity conditions. Ammonia stress led to a predominance of downregulated HSP genes in the liver, particularly hspa2, while upregulation was observed in the gills, especially for hsp90b1. Quantitative real-time PCR analysis corroborated the expression levels under environmental stresses, validating their involvement in stress responses. This investigation provides insights into the molecular mechanisms of HSP70 and HSP90 in T. septentrionalis under stress, offering valuable information for future functional studies of HSPs in teleost evolution, optimizing aquaculture techniques, and developing stress-resistant strains.

The small heat shock protein Hsp20.8 imparts tolerance to high temperatures in the leafminer fly, Liriomyza trifolii (Diptera: Agtomyzidae)

As an environmental factor, temperature impacts the distribution of species and influences interspecific competition. The molecular chaperones encoded by small heat shock proteins (sHsps) are essential for rapid, appropriate responses to environmental stress. This study focuses on Hsp20.8, which encodes a temperature-responsive sHsp in Liriomyza trifolii, an insect pest that infests both agricultural and ornamental crops. Hsp20.8 expression was highest at 39℃ in L. trifolii pupae and adults, and expression levels were greater in pupae than in adults. Recombinant Hsp20.8 was expressed in Escherichia coli and conferred a higher survival rate than the empty vector to bacterial cells exposed to heat stress. RNA interference experiments were conducted using L. trifolii adults and prepupae and the knockdown of Hsp20.8 expression increased mortality in L. trifolii during heat stress. The results expand our understanding of sHsp function in Liriomyza spp. and the ongoing adaptation of this pest to climate change. In addition, this study is also important for predicting the distribution of invasive species and proposing new prevention and control strategies based on temperature adaptation.

The Functionality of IbpA from Acholeplasma laidlawii Is Governed by Dynamic Rearrangement of Its Globular-Fibrillar Quaternary Structure

Small heat shock proteins (sHSPs) represent a first line of stress defense in many bacteria. The primary function of these molecular chaperones involves preventing irreversible protein denaturation and aggregation. In Escherichia coli, fibrillar EcIbpA binds unfolded proteins and keeps them in a folding-competent state. Further, its structural homologue EcIbpB induces the transition of EcIbpA to globules, thereby facilitating the substrate transfer to the HSP70-HSP100 system for refolding. The phytopathogenic Acholeplasma laidlawii possesses only a single sHSP, AlIbpA. Here, we demonstrate non-trivial features of the function and regulation of the chaperone-like activity of AlIbpA according to its interaction with other components of the mycoplasma multi-chaperone network. Our results show that the efficiency of the A. laidlawii multi-chaperone system is driven with the ability of AlIbpA to form both globular and fibrillar structures, thus combining functions of both IbpA and IbpB when transferring the substrate proteins to the HSP70-HSP100 system. In contrast to EcIbpA and EcIbpB, AlIbpA appears as an sHSP, in which the competition between the N- and C-terminal domains regulates the shift of the protein quaternary structure between a fibrillar and globular form, thus representing a molecular mechanism of its functional regulation. While the C-terminus of AlIbpA is responsible for fibrils formation and substrate capture, the N-terminus seems to have a similar function to EcIbpB through facilitating further substrate protein disaggregation using HSP70. Moreover, our results indicate that prior to the final disaggregation process, AlIbpA can directly transfer the substrate to HSP100, thereby representing an alternative mechanism in the HSP interaction network.

Spatiotemporal Patterns of Five Small Heat Shock Protein Genes in Hyphantria cunea in Response to Thermal Stress

Hyphantria cunea (Drury), a destructive polyphagous pest, has been spreading southward after invading northern China, which indicates that this insect species is facing a huge thermal challenge. Small heat shock proteins (sHSPs) function as ATP-independent molecular chaperones that protect insects from heat stress damage. In order to explore the role of sHSPs in the thermotolerance of H. cunea, five novel sHSP genes of H. cunea were cloned, including an orthologous gene (HcHSP21.4) and four species-specific sHSP genes (HcHSP18.9, HcHSP20.1, HcHSP21.5, and HcHSP29.8). Bioinformatics analysis showed that the proteins encoded by these five HcHSPs contained typical α-crystallin domains. Quantitative real-time PCR analysis revealed the ubiquitous expression of all HcHSPs across all developmental stages of H. cunea, with the highest expression levels in pupae and adults. Four species-specific HcHSPs were sensitive to high temperatures. The expression levels of HcHSPs were significantly up-regulated under heat stress and increased with increasing temperature. The expression levels of HcHSPs in eggs exhibited an initial up-regulation in response to a temperature of 40 °C. In other developmental stages, the transcription of HcHSPs was immediately up-regulated at 30 °C or 35 °C. HcHSPs transcripts were abundant in the cuticle before and after heat shock. The expression of HcHSP21.4 showed weak responses to heat stress and constitutive expression in the tissues tested. These results suggest that most of the HcHSPs are involved in high-temperature response and may also have functions in the normal development and reproduction of H. cunea.

HSPB7 oppositely regulates human mesenchymal stromal cell-derived osteogenesis and adipogenesis

BACKGROUND

Recent evidence suggests that accumulation of marrow adipose tissue induced by aberrant lineage allocation of bone marrow-derived mesenchymal stromal cells (BMSCs) contributes to the pathophysiologic processes of osteoporosis. Although master regulators of lineage commitment have been well documented, molecular switches between osteogenesis and adipogenesis are largely unknown.

METHODS

HSPB7 gene expression during osteogenic and adipogenic differentiation of BMSCs was evaluated by qPCR and Western blot analyses. Lentiviral-mediated knockdown or overexpression of HSPB7 and its deletion constructs were used to assess its function. The organization of cytoskeleton was examined by immunofluorescent staining. ALP activity, calcium assay, Alizarin Red S staining and Oil Red O staining were performed in vitro during osteoblast or adipocyte differentiation. SB431542 and Activin A antibody were used to identify the mechanism of Activin A in the regulation of osteogenic differentiation in BMSCs.

RESULTS

In this study, we identified HSPB7 capable of oppositely regulating osteogenic and adipogenic differentiation of BMSCs. HSPB7 silencing promoted adipogenesis while reducing osteogenic differentiation and mineralization. Conversely, overexpression of HSPB7 strongly enhanced osteogenesis, but no effect was observed on adipogenic differentiation. Deletion of the N-terminal or C-terminal domain of HSPB7 led to decreased osteoblastic potency and mineralization. Mechanistically, our data showed that Activin A is a downstream target participating in HSPB7 knockdown-mediated osteogenic inhibition.

CONCLUSIONS

Our findings suggest that HSPB7 plays a positive role in driving osteoblastic differentiation, and with the capability in maintaining the osteo-adipogenesis balance. It holds great promise as a potential therapeutic target in the treatment of bone metabolic diseases.

From Small Peptides to Large Proteins against Alzheimer’sDisease

Alzheimer’s disease (AD) is the most common neurodegenerative disorder in the elderly. The two cardinal neuropathological hallmarks of AD are the senile plaques, which are extracellular deposits mainly constituted by beta-amyloids, and neurofibrillary tangles formed by abnormally phosphorylated Tau (p-Tau) located in the cytoplasm of neurons. Although the research has made relevant progress in the management of the disease, the treatment is still lacking. Only symptomatic medications exist for the disease, and, in the meantime, laboratories worldwide are investigating disease-modifying treatments for AD. In the present review, results centered on the use of peptides of different sizes involved in AD are presented.

Human HspB1, HspB3, HspB5 and HspB8: Shaping these disease factors during vertebrate evolution

Small heat shock proteins (sHSPs) emerged early in evolution and occur in all domains of life and nearly in all species, including humans. Mutations in four sHSPs (HspB1, HspB3, HspB5, HspB8) are associated with neuromuscular disorders. The aim of this study is to investigate the evolutionary forces shaping these sHSPs during vertebrate evolution. We performed comparative evolutionary analyses on a set of orthologous sHSP sequences, based on the ratio of non-synonymous: synonymous substitution rates for each codon. We found that these sHSPs had been historically exposed to different degrees of purifying selection, decreasing in this order: HspB8 > HspB1, HspB5 > HspB3. Within each sHSP, regions with different degrees of purifying selection can be discerned, resulting in characteristic selective pressure profiles. The conserved α-crystallin domains were exposed to the most stringent purifying selection compared to the flanking regions, supporting a 'dimorphic pattern' of evolution. Thus, during vertebrate evolution the different sequence partitions were exposed to different and measurable degrees of selective pressures. Among the disease-associated mutations, most are missense mutations primarily in HspB1 and to a lesser extent in the other sHSPs. Our data provide an explanation for this disparate incidence. Contrary to the expectation, most missense mutations cause dominant disease phenotypes. Theoretical considerations support a connection between the historic exposure of these sHSP genes to a high degree of purifying selection and the unusual prevalence of genetic dominance of the associated disease phenotypes. Our study puts the genetics of inheritable sHSP-borne diseases into the context of vertebrate evolution.

Neighbours matter: Effects of genomic organization on gene expression plasticity in response to environmental stresses during biological invasions

Gene expression regulation has been widely recognized as an important molecular mechanism underlying phenotypic plasticity in environmental adaptation. However, it remains largely unexplored on the effects of genomic organization on gene expression plasticity under environmental stresses during biological invasions. Here, we use an invasive model ascidian, Ciona robusta, to investigate how genomic organization affects gene expression in response to salinity stresses during range expansions. Our study showed that neighboring genes were co-expressed and approximately 30% of stress responsive genes were physically clustered on chromosomes. Such coordinated expression was substantially affected by the physical distance and orientation of genes. Interestingly, the overall expression correlation of neighboring genes was significantly decreased under high salinity stresses, illustrating that the co-expression regulation could be disrupted by salinity challenges. Furthermore, the clustering of genes was associated with their function constraints and expression patterns - operon genes enriched in gene expression machinery had the highest transcriptional activity and expression stability. Notably, our analyses showed that the tail-to-tail genes, mainly involved in biological functions related to phosphorylation, homeostatic process, and ion transport, exhibited higher intrinsic expression variability and greater response to salinity challenges. Altogether, the results obtained here provide new insights into the effects of gene organization on gene expression plasticity under environmental challenges, hence improving our knowledge on mechanisms of rapid environmental adaptation during biological invasions.

Understanding Diversity, Evolution, and Structure of Small Heat Shock Proteins in Annelida Through in Silico Analyses

Small heat shock proteins (sHsps) are oligomeric stress proteins characterized by an α-crystallin domain (ACD). These proteins are localized in different subcellular compartments and play critical roles in the stress physiology of tissues, organs, and whole multicellular eukaryotes. They are ubiquitous proteins found in all living organisms, from bacteria to mammals, but they have never been studied in annelids. Here, a data set of 23 species spanning the annelid tree of life, including mostly transcriptomes but also two genomes, was interrogated and 228 novel putative sHsps were identified and manually curated. The analysis revealed very high protein diversity and showed that a significant number of sHsps have a particular dimeric architecture consisting of two tandemly repeated ACDs. The phylogenetic analysis distinguished three main clusters, two of them containing both monomeric sHsps, and ACDs located downstream in the dimeric sHsps, and the other one comprising the upstream ACDs from those dimeric forms. Our results support an evolutionary history of these proteins based on duplication events prior to the Spiralia split. Monomeric sHsps 76) were further divided into five subclusters. Physicochemical properties, subcellular location predictions, and sequence conservation analyses provided insights into the differentiating elements of these putative functional groups. Strikingly, three of those subclusters included sHsps with features typical of metazoans, while the other two presented characteristics resembling non-metazoan proteins. This study provides a solid background for further research on the diversity, evolution, and function in the family of the sHsps. The characterized annelid sHsps are disclosed as essential for improving our understanding of this important family of proteins and their pleotropic functions. The features and the great diversity of annelid sHsps position them as potential powerful molecular biomarkers of environmental stress for acting as prognostic tool in a diverse range of environments.

HSPB11 is a Prognostic Biomarker Associated with Immune Infiltrates in Hepatocellular Carcinoma

Purpose

Patients and Methods

Results

Conclusion

Transcriptional regulation of small heat shock protein genes by heat shock factor 1 (HSF1) in Liriomyza trifolii under heat stress

Small heat shock proteins (sHSPs) function as molecular chaperones in multiple physiological processes and are active during thermal stress. sHSP expression is controlled by heat shock transcription factor (HSF); however, few studies have been conducted on HSF in agricultural pests. Liriomyza trifolii is an introduced insect pest of horticultural and vegetable crops in China. In this study, the master regulator, HSF1, was cloned and characterized from L. trifolii, and the expression levels of HSF1 and five sHSPs were studied during heat stress. HSF1 expression in L. trifolii generally decreased with rising temperatures, whereas expression of the five sHSPs showed an increasing trend that correlated with elevated temperatures. All five sHSPs and HSF1 showed an upward trend in expression with exposure to 40 ℃ without a recovery period. When a recovery period was incorporated after thermal stress, the expression patterns of HSF1 and sHSPs in L. trifolii exposed to 40 °C was significantly lower than expression with no recovery period. To elucidate potential interactions between HSF1 and sHSPs, double-stranded RNA was synthesized to knock down HSF1 in L. trifolii by RNA interference. The knockdown of HSF1 by RNAi decreased the survival rate and expression of HSP19.5, HSP20.8, and HSP21.3 during high-temperature stress. This study expands our understanding of HSF1-regulated gene expression in L. trifolii exposed to heat stress.

Transcriptome analysis reveals gene expression differences in Liriomyza trifolii exposed to combined heat and abamectin exposure

Liriomyza trifolii is an invasive pest of horticultural and vegetable crops that possesses robust competitive advantages that enable it to replace closely-related species. High temperatures often occur concomitantly with insecticide usage during L. trifolii outbreaks. In this study, we compared the transcriptomes of L. trifolii exposed to high temperature (40 °C T40), insecticide (LC50 of technical grade abamectin, I50) and combined high temperature and abamectin exposure (IT5040, I50 followed by T40; and TI4050, T40 followed by I50). RNA-seq generated and revealed 44,633 unigenes with annotation data; these were compared with COG and KEGG databases for functional classification and enrichment analysis. Compared with the I50 treatment, COG classification indicated that 'post-translational modification, protein turnover, chaperones' was enriched in the IT5040 treatment. In the TI4050 treatment, 'carbohydrate transport and metabolism' was the most abundant group. The most enriched KEGG pathways in the TI4050 and IT5040 treatments were 'longevity regulating pathway - multiple species' and 'protein processing in endoplasmic reticulum', respectively. Subsequent annotation and enrichment analyses indicated that stress-related genes such as CYP450s and HSPs were differentially expressed in the I50 vs. TI4050 or I50 vs. IT5040 treatment groups. Three commercial insecticide formulations were also used to further verify the expression of selected differentially-expressed genes. This study will be conductive to consider the temperature effect on insecticide tolerance in L. trifolii, and provides a framework for improving the application efficiency of insecticides in hot weather, which will ultimately reduce the overuse of pesticides.

Rapid Genomic Evolution Drives the Diversification of Male Reproductive Genes in Dung Beetles

The molecular basis for the evolution of novel phenotypes is a central question in evolutionary biology. In recent years, dung beetles have emerged as models for novel trait evolution as they possess distinct precopulatory traits such as sexually dimorphic horns on their head and thorax. Here, we use functional and evolutionary genomics to investigate the origins and the evolution of postcopulatory reproductive traits in male dung beetles. Male ejaculates that underlie postcopulatory sexual selection are excellent candidates to study novel trait evolution as they are complex, fast evolving, and often highly divergent in insects. We assemble de novo transcriptomes of male accessory glands and testes of a widespread dung beetle, Catharsius molossus, and we perform an evolutionary analysis of closely and distantly related insect genomes. Our results show there is rapid innovation at the genomic level even among closely related dung beetles. Genomic expansion and contraction drive the divergence of male reproductive traits and their functions. The birth of scores of completely novel reproductive genes is reinforced by the recruitment of these genes for high expression in male reproductive tissues, especially in the accessory glands. We find that male accessory glands of C. molossus are specialized for secretory function and express female, egg, and embryo-related genes as well as serine protease inhibitors, whilst the testes are specialized for spermatogenesis and sperm function. Finally, we touch upon putative functions of these evolutionary novelties using structure-function analysis as these proteins bear no homology to any other known proteins.

Characterization and functional analysis of Cshsp19.0 encoding a small heat shock protein in Chilo suppressalis (Walker)

Small heat shock proteins (sHSPs) function as ATP-independent chaperones that preserve cellular proteostasis under stressful conditions. In this study, Cshsp19.0, which encodes a new small heat shock protein, was isolated and characterized from Chilo suppressalis (Walker) to better understand the contribution of sHSPs to insect development and stress tolerance. The full-length Cshsp19.0 cDNA was 697 bp and encoded a 19.0 kDa protein with an isoelectric point of 5.95. Phylogenetic analysis and amino acid alignments indicated that Cshsp19.0 is a member of the sHSP family. Cshsp19.0 was expressed at maximal levels in foreguts and showed the least amount of expression in fat bodies. Expression analysis in different developmental stages of C. suppressalis revealed that Cshsp19.0 was most highly expressed in 1st instar larvae. Furthermore, Cshsp19.0 was upregulated when insects were exposed to heat and cold stress for a 2-h period. There were significant differences in the male and female pupae in response to humidity; Cshsp19.0 expression increased in male pupae as RH increased, whereas the inverse pattern was observed in female pupae. Larvae exhibited a lower rate of survival when Cshsp19.0 was silenced by a nanomaterial-promoted RNAi method. The results confirm that Cshsp19.0 functions to increase environmental stress tolerance and regulates physiological activities in C. suppressalis.

Interplay between Heat Shock Proteins, Inflammation, and Pain: A promising Therapeutic Approach

Heat Shock Proteins (HSPs) are important molecular chaperones that facilitate many functions of the cells. They also play a pivotal role in cell survival, especially in the presence of stressors, including nutritional deprivation, lack of oxygen, fever, alcohol, inflammation, oxidative stress, heavy metals, as well as conditions that cause injury and necrosis. In the face of a painful stimulus encounter, many factors could be associated with pain that may include nitric oxide, excitatory amino acids, reactive oxygen species (ROS) formation, prostaglandins, and inflammatory cytokines. One influential factor affecting pain reduction is the expression of HSPs that act as a ROS scavenger, regulate the inflammatory cytokines, and reduce pain responses subsequently. Hence, we assembled information on the painkilling attributes of HSPs. In this field of research, new painkillers could be developed by targetting HSPs to alleviate pain and widen our grasp of pain in pathological conditions and neurological diseases.

Physiological Functions of Heat Shock Proteins

Heat shock proteins (HSPs) are molecular chaperones involved in a variety of life activities. HSPs function in the refolding of misfolded proteins, thereby contributing to the maintenance of cellular homeostasis. Heat shock factor (HSF) is activated in response to environmental stresses and binds to heat shock elements (HSEs), promoting HSP translation and thus the production of high levels of HSPs to prevent damage to the organism. Here, we summarize the role of molecular chaperones as anti-heat stress molecules and their involvement in immune responses and the modulation of apoptosis. In addition, we review the potential application of HSPs to cancer therapy, general medicine, and the treatment of heart disease.

Identification of five small heat shock protein genes in Spodoptera frugiperda and expression analysis in response to different environmental stressors

Spodoptera frugiperda (J. E. Smith) is a highly adaptable polyphagous migratory pest in tropical and subtropical regions. Small heat shock proteins (sHsps) are molecular chaperones that play important roles in the adaptation to various environment stressors. The present study aimed to clarify the response mechanisms of S. frugiperda to various environmental stressors. We obtained five S. furcifera sHsp genes (SfsHsp21.3, SfsHsp20, SfsHsp20.1, SfsHsp19.3, and SfsHsp29) via cloning. The putative proteins encoded by these genes contained a typical α-crystallin domain. The expression patterns of these genes during different developmental stages, in various tissues of male and female adults, as well as in response to extreme temperatures and UV-A stress were studied via real-time quantitative polymerase chain reaction. The results showed that the expression levels of all five SfsHsp genes differed among the developmental stages as well as among the different tissues of male and female adults. The expression levels of most SfsHsp genes under extreme temperatures and UV-A-induced stress were significantly upregulated in both male and female adults. In contrast, those of SfsHsp20.1 and SfsHsp19.3 were significantly downregulated under cold stress in male adults. Therefore, the different SfsHsp genes of S. frugiperda play unique regulatory roles during development as well as in response to various environmental stressors.

Involvement of small heat shock proteins (sHsps) in developmental stages of fall armyworm, Spodoptera frugiperda and its expression pattern under abiotic stress condition

Fall armyworm (FAW), Spodoptera frugiperda a recent invasive pest in India is reported to cause significant damage by feeding voraciously on maize and other economic crops from tropical to temperate provinces. It is becoming an arduous challenge to control the pest as it can survive in a wide range of temperature conditions and is already said to develop resistance towards certain insecticides. The small Heat shock proteins (hereafter, sHsps) are known to play an important role in adaptation of insects under such stress conditions. Our present study involved characterization of the three sHsps genes (sHsp19.74, sHsp20.7 and sHsp19.07) which encoded proteins of about 175, 176 and 165 amino acids with a conserved α-crystalline domain. Phylogenetic analysis of deduced amino acid sequences of the three genes showed strong similarity with the other lepidopteran sHsps. The effect of different growth stages on the expression profile of these stress proteins has also been studied and the Quantitative real time PCR (qRT-PCR) analysis revealed that the transcript level of sHsp19.07 and sHsp20.7 were significantly upregulated under extreme heat (44 °C) and cold (5 °C) stress. However, sHsp19.74 responded only to heat treatment but not to the cold treatment. In addition, the expression profile of all three sHsps was significantly lower in the larval stage (5^th instar). Chlorantraniliprole treatment resulted in maximum expression of sHsp19.07 and sHsp20.7 after 12hr of exposure to the insecticide. Meanwhile, the same expression was observed after 8hr of exposure in case of sHsp19.74. These results proved that the sHsp genes of S. frugiperda were induced and modulated in response to abiotic stress, thus influencing the physiological function leading to survival of FAW in diversified climate in India.

Small heat shock protein 22 kDa can modulate the aggregation and liquid-liquid phase separation behavior of tau

Alzheimer's disease is a progressive fatal neurodegenerative disease with no cure or effective treatments. The hallmarks of disease include extracellular plaques and intracellular tangles of aggregated protein. The intracellular tangles consist of the microtubule associated protein tau. Preventing the pathological aggregation of tau may be an important therapeutic approach to treat disease. In this study we show that small heat shock protein 22 kDa (Hsp22) can prevent the aggregation of tau in vitro. Additionally, tau can undergo liquid-liquid phase separation (LLPS) in the presence of crowding reagents which causes it to have an increased aggregation rate. We show that Hsp22 can modulate both the aggregation and LLPS behavior of tau in vitro.

Characterization of Two Small Heat Shock Protein Genes (Hsp17.4 and Hs20.3) from Sitodiplosis mosellana, and Their Expression Regulation during Diapause

Simple Summary

Small heat shock proteins (sHsps) play important roles in thermal adaptation of various organisms, and insect diapause. Sitodiplosis mosellana, a key pest of wheat worldwide, undergoes obligatory larval diapause in soil to survive adverse temperature extremes during hot summers and cold winters. The objectives of this study were to characterize two sHsp genes from S. mosellana (SmHsp17.4 and SmHsp20.3), and determine their expression in response to diapause, extreme high/low temperatures, or 20-hydroxyecdysone (20E) treatment. Expression of SmHsp17.4 was down-regulated upon entry into diapause, but up-regulated during the shift to post-diapause quiescence. In contrast, expression of SmHsp20.3 was not affected by entry into diapause, but was pronounced during summer and winter. Furthermore, transcripts of both SmHsps were highly responsive to heat (≥35 °C) and cold (≤−5 °C) during diapause, and topical application of 20E on diapausing larvae also induced SmHsp17.4 in a dose-dependent manner. Notably, the recombinant SmHsp17.4 and SmHsp20.3 exhibited significant molecular chaperone activity. In conclusion, SmHsp17.4 and SmHsp20.3 play essential roles in heat/cold adaptation, and 20E-mediated SmHsp17.4 was also likely involved in diapause termination. Results have improved our understanding of the molecular mechanism underlying diapause and related stress tolerance in S. mosellana.

Abstract

Sitodiplosis mosellana, a periodic but devastating wheat pest that escapes temperature extremes in summer and winter by undergoing obligatory diapause. To determine the roles of small heat shock proteins (sHsps) in diapause of S. mosellana, we characterized two sHsp genes, SmHsp17.4 and SmHsp20.3, from this species. Both SmHsps contained the conserved α-crystallin domain and the carboxy-terminal I/VXI/V motif of the sHsp family. SmHsp17.4 had one intron while SmHsp20.3 had none. Quantitative PCR revealed that SmHsp17.4 expression decreased after diapause initiation, but substantially increased during transition to post-diapause quiescence. In contrast, SmHsp20.3 expression was not affected by entry of diapause, but was clearly up-regulated during summer and winter. Short-term more severe heat-stress (≥35 °C) of over-summering larvae or cold-stress (≤−5 °C) of over-wintering larvae could stimulate higher expression of both genes, and SmHsp17.4 was more responsive to cold stress while SmHsp20.3 was more sensitive to heat stress. Notably, transcription of SmHsp17.4, but not SmHsp20.3, in diapausing larvae was inducible by 20-hydroxyecdysone (20E). Recombinant SmHsp17.4 and SmHsp20.3 proteins also displayed significant chaperone functionality. These findings suggest that both SmHsps play key roles in stress tolerance during diapause; and 20E-regulated SmHsp17.4 was also likely involved in diapause termination.

PiP2 favors an α-helical structure of non-recombinant Hsp12 of Saccharomyces cerevisiae

Hsp12 is a small heat shock protein of Saccharomyces cerevisiae upregulated in response to various stresses. Non recombinant Hsp12 has been purified and characterized. Using circular dichroism (CD), Isothermal Titration Calorimetry (ITC) and Differential Scanning Calorimetry (DSC), it has been demonstrated that the native Hsp12 is monomeric and intrinsically disordered (IDP). Hsp12 gains in structure in the presence of specific lipids (PiP₂). The helical form binds to liposomes models membrane with high affinity, leading to their rigidification. These results suggest that hydrophobic and ionic interactions are involved. Hsp12 is most likely a membrane chaperone expressed during stresses in Saccharomyces cerevisiae.

HSPB5 (αB-crystallin) confers protection against paraquat-induced oxidative stress at the organismal level in a tissue-dependent manner

Oxidative stress is one of the major and continuous stresses, an organism encounters during its lifetime. Tissues such as the brain, liver and muscles are more prone to damage by oxidative stress due to their metabolic activity, differences in physiological and adaptive processes. One of the defence mechanisms against continuous oxidative stress is a set of small heat shock proteins. αB-Crystallin/HSPB5, a small heat shock protein, gets upregulated under stress and acts as a molecular chaperone. In addition to acting as a molecular chaperone, HSPB5 is shown to have a role in other cytoprotective functions such as inhibition of apoptosis, prevention of oxidative stress and stabilisation of cytoskeletal system. Such protection in vivo, at the organism level, particularly in a tissue-dependent manner, has not been investigated. We have expressed HSPB5 in fat body (liver), neurons and specifically in dopaminergic and motor neurons in Drosophila and investigated its protective effect against paraquat-induced oxidative stress. We observed that expression of HSPB5 in neurons and fat body confers protection against paraquat-induced oxidative stress. Expression in dopaminergic neurons showed a higher protective effect. Our results clearly establish the protective ability of HSPB5 in vivo; the extent of protection, however, varies depending on the tissue in which it is expressed. Interestingly, neuronal expression of HSPB5 resulted in an improvement in negative geotropic behaviour, whereas specific expression in muscle tissue did not show such a beneficial effect.

Transcriptional Responses of the Heat Shock Protein 20 (Hsp20) and 40 (Hsp40) Genes to Temperature Stress and Alteration of Life Cycle Stages in the Harmful Alga Scrippsiella trochoidea (Dinophyceae)

Simple Summary

As the greatest contributors to harmful algal blooms, dinoflagellates account for roughly 75% of bloom events, which become an escalating threat to coastal ecosystems and cause substantial economic loss worldwide. Resting cyst production and broad temperature tolerance are well proven as adaptive strategies for blooming dinoflagellates; however, to date, the underlying molecular information is scarce. In the present study, we characterized two heat shock protein genes from the representative dinoflagellate Scrippsiella trochoidea, with the aim to primarily determine their possible roles in response to temperature stress and alteration of the life cycle. The yielded results enhance our knowledge about the functions of cross-talk of different Hsp members in temperature adaptation of dinoflagellates and facilitate further exploration in their potential physiological relevance during different life-stage alternation in this ecological important lineage.

Abstract

The small heat shock protein (sHsp) and Hsp40 are Hsp members that have not been intensively investigated but are functionally important in most organisms. In this study, the potential roles of a Hsp20 (StHsp20) and a Hsp40 (StHsp40) in dinoflagellates during adaptation to temperature fluctuation and alteration of different life stages were explored using the representative harmful algal blooms (HABs)-causative dinoflagellate species, Scrippsiella trochoidea. We isolated the full-length cDNAs of the two genes via rapid amplification of cDNA ends (RACE) and tracked their differential transcriptions via real-time qPCR. The results revealed StHsp20 and StHsp40 exhibited mRNA accumulation patterns that were highly similar in response to heat stress but completely different toward cold stress, which implies that the mechanisms underlying thermal and cold acclimation in dinoflagellates are regulated by different sets of genes. The StHsp20 was probably related to the heat tolerance of the species, and StHsp40 was closely involved in the adaptation to both higher and lower temperature fluctuations. Furthermore, significantly higher mRNA abundance of StHsp40 was detected in newly formed resting cysts, which might be a response to intrinsic stress stemmed from encystment. This finding also implied StHsp40 might be engaged in resting cyst formation of S. trochoidea. Our findings enriched the knowledge about possible cross-talk of different Hsp members in dinoflagellates and provided clues to further explore the molecular underpinnings underlying resting cyst production and broad temperature tolerance of this group of HABs contributors.

Comparative transcriptome analysis of three invasive leafminer flies provides insights into interspecific competition

Liriomyza spp. (Diptera: Agromyzidae) represent a group of economically-significant highly polyphagous pests of plants grown in field and greenhouse conditions. Liriomyza spp. share similar biological and morphological characteristics, and complex interspecific interactions have been documented among these species in various geographical regions. Where the displacement of one of these species by the other has been studied, no unique mechanisms have been identified as causing it. The impact of competitive factors (such as, insecticide tolerance, thermotolerance, and adaptability to cropping systems) may be unique to specific geographic regions of Liriomyza spp., but more research is needed to confirm these hypotheses. In this study, RNA-seq was used to determine the transcriptomes of three closely-related leafminers, e.g. L. sativae, L. trifolii, and L. huidobrensis. Over 20 Gb of clean reads were generated and assembled into unique transcriptomes, and 38,747 unigenes were annotated in different databases. In pairwise comparisons, L. trifolii and L. sativae had more up-regulated genes than L. huidobrensis. With respect to common differentially-expressed genes (Co-DEGs), the three leafminers exhibited distinct groups of highly-expressed gene clusters. When genes related to competitive factors were compared, expression patterns in L. trifolii and L. sativae were more closely related to each other than to L. huidobrensis. The data suggest that DEGs involved in competitive factors may play a key role in competition and displacement of leafminers. The divergent genes identified in this study will be valuable in revealing possible mechanisms of invasion, displacement and interspecific competition in Liriomyza spp.

Modulation of protein fate decision by small molecules: targeting molecular chaperone machinery

Modulation of protein fate decision and protein homeostasis plays a significant role in altering the protein level, which acts as an orientation to develop drugs with new mechanisms. The molecular chaperones exert significant biological functions on modulation of protein fate decision and protein homeostasis under constantly changing environmental conditions through extensive protein–protein interactions (PPIs) with their client proteins. With the help of molecular chaperone machinery, the processes of protein folding, trafficking, quality control and degradation of client proteins could be arranged properly. The core members of molecular chaperones, including heat shock proteins (HSPs) family and their co-chaperones, are emerging as potential drug targets since they are involved in numerous disease conditions. Development of small molecule modulators targeting not only chaperones themselves but also the PPIs among chaperones, co-chaperones and clients is attracting more and more attention. These modulators are widely used as chemical tools to study chaperone networks as well as potential drug candidates for a broader set of diseases. Here, we reviewed the key checkpoints of molecular chaperone machinery HSPs as well as their co-chaperones to discuss the small molecules targeting on them for modulation of protein fate decision.

Molecular characterization of a heat shock protein 21 (Hsp21) from red swamp crayfish, Procambarus clarkii in response to immune stimulation

Small heat shock proteins are a molecular chaperone and implicated in various physiological and stress processes in animals. However, the immunological functions of Hsp genes remain to elucidate in the crustaceans, particularly in red swamp crayfish, Procambarus clarkii. Here we report the cloning of heat shock protein 21 from the P. clarkii (hereafter Pc-Hsp21). The open reading frame of Pc-Hsp21 was 555 base pairs, encoding a protein of 184 amino acid residues with an alpha-crystallin family domain. Quantitative real-time PCR (qRT-PCR) analysis revealed a constitutive transcript expression of Pc-Hsp21 in the tested tissue, with the highest in hepatopancreas. The transcript abundance for this gene enhanced in hepatopancreas following immune challenge with the lipopolysaccharide, peptidoglycan, and poly I:C compared to the control group. The depletion of Pc-Hsp21 by double-stranded RNA altered transcript expression profiles of several genes in hepatopancreas, genes involved in the crucial immunological pathways of P. clarkii. These results suggest that Pc-Hsp21 plays an essential biological role in the microbial stress response by modulating the expression of immune-related genes in P. clarkii.

Genetic Constraints, Transcriptome Plasticity, and the Evolutionary Response to Climate Change

In situ adaptation to climate change will be critical for the persistence of many ectotherm species due to their relative lack of dispersal capacity. Climate change is causing increases in both the mean and the variance of environmental temperature, each of which may act as agents of selection on different traits. Importantly, these traits may not be heritable or have the capacity to evolve independently from one another. When genetic constraints prevent the "baseline" values of thermal performance traits from evolving rapidly, phenotypic plasticity driven by gene expression might become critical. We review the literature for evidence that thermal performance traits in ectotherms are heritable and have genetic architectures that permit their unconstrained evolution. Next, we examine the relationship between gene expression and both the magnitude and duration of thermal stress. Finally, we identify genes that are likely to be important for adaptation to a changing climate and determine whether they show patterns consistent with thermal adaptation. Although few studies have measured narrow-sense heritabilities of thermal performance traits, current evidence suggests that the end points of thermal reaction norms (tolerance limits) are moderately heritable and have the potential to evolve rapidly. By contrast, performance at intermediate temperatures has substantially lower evolutionary potential. Moreover, evolution in many species appears to be constrained by genetic correlations such that populations can adapt to either increases in mean temperature or temperature variability, but not both. Finally, many species have the capacity for plastic expression of the transcriptome in response to temperature shifts, with the number of differentially expressed genes increasing with the magnitude, but not the duration, of thermal stress. We use these observations to develop a conceptual model that describes the likely trajectory of genome evolution in response to changes in environmental temperature. Our results indicate that extreme weather events, rather than gradual increases in mean temperature, are more likely to drive genetic and phenotypic change in wild ectotherms.

Characterization and expression analysis of genes encoding three small heat shock proteins in the oriental armyworm, Mythimna separata (Walker)

Small heat shock proteins (sHsps) function in the response of insects to abiotic stress; however, their role in response to biotic stress has been under-investigated. Mythimna separata, the oriental armyworm, is polyphenetic and exhibits gregarious and solitary phases in response to high and low population density, respectively. In this study, three genes were identified encoding sHsps, namely MsHsp19.7, MsHsp19.8 and MsHsp21.4, and expression levels in solitary and gregarious M. separata were compared. The deduced protein sequences of the three MsHsps had molecular weights of 19.7, 19.8 and 21.4 kDa, respectively, and contained a conserved α-crystalline domain. Real-time PCR analyses revealed that the three sHsps were transcribed in all developmental stages and were dramatically up-regulated at the 6^th larval stage in gregarious individuals. Expression of the three MsHsps was variable in different tissues of 6^th instar larvae, but exhibited consistent up- and down-regulation in the hindgut and Malpighian tubules of gregarious individuals, respectively. In addition, MsHsp19.7 and MsHsp19.8 were significantly induced when solitary forms were subjected to crowding for 36 h, but all three MsHsps were down-regulated when gregarious forms were isolated. Our findings suggest that population density functions as a stress factor and impacts MsHsps expression in M. separata.

Structural aspects of the human small heat shock proteins related to their functional activities

Small heat shock proteins function as chaperones by binding unfolding substrate proteins in an ATP-independent manner to keep them in a folding-competent state and to prevent irreversible aggregation. They play crucial roles in diseases that are characterized by protein aggregation, such as neurodegenerative and neuromuscular diseases, but are also involved in cataract, cancer, and congenital disorders. For this reason, these proteins are interesting therapeutic targets for finding molecules that could affect the chaperone activity or compensate specific mutations. This review will give an overview of the available knowledge on the structural complexity of human small heat shock proteins, which may aid in the search for such therapeutic molecules.

Ethylene and RIPENING INHIBITOR Modulate Expression of SlHSP17.7A, B Class I Small Heat Shock Protein Genes During Tomato Fruit Ripening

Heat shock proteins (HSPs) are ubiquitous and highly conserved in nature. Heat stress upregulates their gene expression and now it is known that they are also developmentally regulated. We have studied regulation of small HSP genes during ripening of tomato fruit. In this study, we identify two small HSP genes, SlHSP17.7A and SlHSP17.7B, localized on tomato Chr.6 and Chr.9, respectively. Each gene encodes proteins constituting 154 amino acids and has characteristic domains as in other sHSP genes. We found that SlHSP17.7A and SlHSP17.7B gene expression is low in the vegetative tissues as compared to that in the fruit. These sHSP genes are characteristically expressed in a fruit-ripening fashion, being upregulated during the ripening transition of mature green to breaker stage. Their expression patterns mirror that of the rate-limiting ethylene biosynthesis gene ACC (1-aminocyclopropane-1-carboxylic acid) synthase, SlACS2, and its regulator SlMADS-RIN. Exogenous application of ethylene to either mature green tomato fruit or tomato leaves suppressed the expression of both the SlHSP17.7A, B genes. Notably and characteristically, a transgenic tomato line silenced for SlACS2 gene and whose fruits produce ~50% less ethylene in vivo, had higher expression of both the sHSP genes at the fruit ripening transition stages [breaker (BR) and BR+3] than the control fruit. Moreover, differential gene expression of SlHSP17.7A versus SlHSP17.7B gene was apparent in the tomato ripening mutants-rin/rin, nor/nor, and Nr/Nr, with the expression of SlHSP17.7A being significantly reduced but that of SlHSP17.7B significantly upregulated as compared to the wild type (WT). These data indicate that ethylene negatively regulates transcriptional abundance of both these sHSPs. Transient overexpression of the ripening regulator SlMADS-RIN in WT and ACS2-AS mature green tomato fruits suppressed the expression of SlHSP17.7A but not that of SlHSP17.7B. Thus, ethylene directly or in tune with SlMADS-RIN regulates the transcript abundance of both these sHSP genes.

Generation and proteome profiling of PBMC-originated, iPSC-derived lentoid bodies

Here, we report proteome profiling of peripheral blood mononuclear cell (PBMC)-originated, induced pluripotent stem cell (iPSC)-derived, lens-like organoids termed lentoid bodies at two differentiation time points. A small aliquot of the blood sample was ascertained to collect PBMCs that were reprogrammed to iPSCs. The PBMC-originated, iPSCs were differentiated to lentoid bodies employing the "fried egg" method. Quantitative real-time PCR (qRT-PCR) analysis revealed increased expression levels of lens-associated markers in lentoid bodies while transmission electron microscopy identified closely packed lens epithelial- and differentiating fiber-like cells in lentoid bodies. Total cellular protein was extracted from lentoid bodies at differentiation day 25 and mass spectrometry identified a total of 9,473 proteins. The low counts of crystallin proteins at differentiation day 25 prompted us to re-examine the proteome at differentiation day 35 as we reasoned that 10 additional days of differentiation will increase the crystallin count. However, we did not detect any substantial increase in crystallin protein counts at differentiation day 35. In conclusion, we report generation and proteome profiles of PBMC-originated, iPSC-derived lentoid bodies at multiple differentiation time points.

Comparative transcriptome analysis of hESC- and iPSC-derived lentoid bodies

The ocular lens serves as an excellent system to investigate the intricate details of development and differentiation. Generation of lentoid bodies or lens-like structures using pluripotent stem cells is important for understanding the processes critical for lens morphogenesis and the mechanism of cataractogenesis. We previously reported the generation of peripheral blood mononuclear cell (PBMC)-originated, induced pluripotent stem cells (iPSCs). Here, we report generation of lentoid bodies from human embryonic stem cells (hESCs) and (PBMC)-originated, iPSCs employing the “fried egg” method with brief modifications. The ultrastructure analysis of hESC- and iPSC-derived lentoid bodies identified closely packed lens epithelial- and differentiating fiber-like cells. In addition, we performed RNA sequencing (RNA-Seq) based transcriptome profiling of hESC- and iPSC-derived lentoid bodies at differentiation day 25. Next-generation RNA sequencing (RNA-Seq) of hESC- and iPSC-derived lentoid bodies detected expression (≥0.659 RPKM) of 13,975 and 14,003 genes, respectively. Comparative transcriptome analysis of hESC- and iPSC-derived lentoid bodies revealed 13,563 (>96%) genes common in both datasets. Among the genes common in both transcriptome datasets, 12,856 (~95%) exhibited a quantitatively similar expression profile. Next, we compared the mouse lens epithelial and fiber cell transcriptomes with hESC- and iPSC-derived lentoid bodies transcriptomes and identified > 96% overlap with lentoid body transcriptomes. In conclusion, we report first-time comparative transcriptome analysis of hESC- and iPSC-derived lentoid bodies at differentiation day 25.

Molecular Cloning and Characterization of Small Heat Shock Protein Genes in the Invasive Leaf Miner Fly, Liriomyza trifolii

Small heat shock proteins (sHSPs) comprise numerous proteins with diverse structure and function. As molecular chaperones, they play essential roles in various biological processes, especially under thermal stresses. In this study, we identified three sHSP-encoding genes, LtHSP19.5, LtHSP20.8 and LtHSP21.7b from Liriomyza trifolii, an important insect pest of ornamental and vegetable crops worldwide. Putative proteins encoded by these genes all contain a conserved α-crystallin domain that is typical of the sHSP family. Their expression patterns during temperature stresses and at different insect development stages were studied by reverse-transcription quantitative PCR (RT-qPCR). In addition, the expression patterns were compared with those of LtHSP21.3 and LtHSP21.7, two previously published sHSPs. When pupae were exposed to temperatures ranging from −20 to 45 °C for 1 h, all LtsHSPs were strongly induced by either heat or cold stresses, but the magnitude was lower under the low temperature range than high temperatures. Developmentally regulated differential expression was also detected, with pupae and prepupae featuring the highest expression of sHSPs. Results suggest that LtsHSPs play a role in the development of the invasive leaf miner fly and may facilitate insect adaptation to climate change.

Small Heat Shock Proteins, Big Impact on Protein Aggregation in Neurodegenerative Disease

Misfolding, aggregation, and aberrant accumulation of proteins are central components in the progression of neurodegenerative disease. Cellular molecular chaperone systems modulate proteostasis, and, therefore, are primed to influence aberrant protein-induced neurotoxicity and disease progression. Molecular chaperones have a wide range of functions from facilitating proper nascent folding and refolding to degradation or sequestration of misfolded substrates. In disease states, molecular chaperones can display protective or aberrant effects, including the promotion and stabilization of toxic protein aggregates. This seems to be dependent on the aggregating protein and discrete chaperone interaction. Small heat shock proteins (sHsps) are a class of molecular chaperones that typically associate early with misfolded proteins. These interactions hold proteins in a reversible state that helps facilitate refolding or degradation by other chaperones and co-factors. These sHsp interactions require dynamic oligomerization state changes in response to diverse cellular triggers and, unlike later steps in the chaperone cascade of events, are ATP-independent. Here, we review evidence for modulation of neurodegenerative disease-relevant protein aggregation by sHsps. This includes data supporting direct physical interactions and potential roles of sHsps in the stewardship of pathological protein aggregates in brain. A greater understanding of the mechanisms of sHsp chaperone activity may help in the development of novel therapeutic strategies to modulate the aggregation of pathological, amyloidogenic proteins. sHsps-targeting strategies including modulators of expression or post-translational modification of endogenous sHsps, small molecules targeted to sHsp domains, and delivery of engineered molecular chaperones, are also discussed.

Characterization of genes encoding small heat shock proteins from Bemisia tabaci and expression under thermal stress

Small heat shock proteins (sHSPs) are probably the most diverse in structure and function among the various super-families of stress proteins, and they play essential roles in various biological processes. The sweet potato whitefly, Bemisia tabaci (Gennadius), feeds in the phloem, transmits several plant viruses, and is an important pest on cotton, vegetables and ornamentals. In this research, we isolated and characterized three α-crystallin/sHSP family genes (Bthsp19.5, Bthsp19.2, and Bthsp21.3) from Bemisia tabaci. The three cDNAs encoded proteins of 171, 169, and 189 amino acids with calculated molecular weights of 19.5, 19.2, and 21.3 kDa and isoelectric points of 6.1, 6.2, and 6.0, respectively. The deduced amino acid sequences of the three genes showed strong similarity to sHSPs identified in Hemiptera and Thysanoptera insects species. All three sHSPs genes from Bemisia tabaci lacked introns. Quantitative real-time PCR analyses revealed that the three BtsHSPs genes were significantly up-regulated in Bemisia tabaci adults and pupae during high temperature stress (39, 41, 43, and 45 °C) but not in response to cold temperature stress (-6, -8, -10, and -12 °C). The expression levels of Bthsp19.2 and Bthsp21.3 in pupae was higher than adults in response to heat stress, while the expression level of Bthsp19.5 in adults was higher than pupae. In conclusion, this research results show that the sHSP genes of Bemisia tabaci had shown differential expression changes under thermal stress.

Identification and Expression Analysis of Four Small Heat Shock Protein Genes in Cigarette Beetle, Lasioderma serricorne (Fabricius)

Small heat shock proteins (sHsps) are molecular chaperones that play crucial roles in the stress adaption of insects. In this study, we identified and characterized four sHsp genes (LsHsp19.4, 20.2, 20.3, and 22.2) from the cigarette beetle, Lasioderma serricorne (Fabricius). The four cDNAs encoded proteins of 169, 180, 181, and 194 amino acids with molecular weights of 19.4, 20.2, 20.3, and 22.2 kDa, respectively. The four LsHsp sequences possessed a typical sHsp domain structure. Quantitative real-time PCR analyses revealed that LsHsp19.4 and 20.3 transcripts were most abundant in pupae, whereas the transcript levels of LsHsp20.2 and 22.2 were highest in adults. Transcripts of three LsHsp genes were highly expressed in the larval fat body, whereas LsHsp20.2 displayed an extremely high expression level in the gut. Expression of the four LsHsp genes was dramatically upregulated in larvae exposed to 20-hydroxyecdysone. The majority of the LsHsp genes were significantly upregulated in response to heat and cold treatments, while LsHsp19.4 was insensitive to cold stress. The four genes were upregulated when challenged by immune triggers (peptidoglycan isolated from Staphylococcus aureus and from Escherichia coli 0111:B4). Exposure to CO₂ increased LsHsp20.2 and 20.3 transcript levels, but the LsHsp19.4 transcript level declined. The results suggest that different LsHsp genes play important and distinct regulatory roles in L. serricorne development and in response to diverse stresses.

Effects on tadpole snail gene expression after exposure to vinclozolin

The fungicide vinclozolin (Vz) is an endocrine disruptor with known anti-androgenic activity in vertebrates. However, there is a lack of information about the Vz mode of action in invertebrates, although some studies have shown that this compound can produce alterations in different species. Transcriptional activity was analyzed in the freshwater snail Physella acuta in order to elucidate putative cellular processes altered by this chemical during a response. In order to identify potential molecular biomarkers, a de novo transcriptome was generated for this species that constitutes a valuable source for future studies. This data, together with some already available data, permitted the identification of several genes related to detoxification mechanisms (Cyp2u1, Cyp3a7, Cyp4f22, GSTo1, GSTt2, and MRP1), stress response (Hsp20.4, Hsp17, Hsp16.6, and Cu,Zn-SOD), the hormonal system (Estrogen Receptor and Hsp90), apoptosis (Casp3), and copper homeostasis (ATOX1). Using quantitative Real-Time polymerase chain reaction, mRNA levels of these genes were examined in snails exposed to 20 or 200 µg/L Vz for 24 h. The results showed an overall weak response, with downregulation of Hsp20.4 and no statistically significant change for the other genes. These findings suggest that P. acuta can manage the concentrations of Vz found in the environment with no relevant activation of the pathways analyzed, although additional studies are needed for longer exposure times and including other metabolic pathways. The new genes described open the range of processes that can be studied at the molecular level in toxicity tests.

Molecular characterization and expression patterns of Phenacoccus solenopsis (Hemiptera: Pseudococcidae) heat shock protein genes and their response to host stress

As a polyphagous insect, little is known at the molecular level about the effects of different host plants on physiological changes in Phenacoccus solenopsis. In this study, four heat shock protein (Hsp) genes (PsHsp60, PsHsp70, PsHsp90, and PsHsp20.7) were identified from the transcriptome of P. solenopsis. Analysis of Hsp expression levels revealed significant differences in Hsp gene expression levels in P. solenopsis fed on different host plants. In host conversion tests, the expression levels of PsHsp90 and PsHsp60 were upregulated after transfer of second instar nymphs from tomato to cotton. The expression levels of PsHsp70 and PsHsp20.7 were, respectively, significantly upregulated at 9 and 48 hr after transfer from tomato to Hibiscus. The results of this study aid molecular characterization and understanding of the expression patterns of Hsp genes during different developmental stages and host transfer of P. solenopsis.

Characterization and functional analysis of hsp18.3 gene in the red flour beetle, Tribolium castaneum

Small heat shock proteins (sHSPs) are diverse and mainly function as molecular chaperones to protect organisms and cells from various stresses. In this study, hsp18.3, one Tribolium castaneum species-specific shsp, has been identified. Quantitative real-time polymerase chain reaction illustrated that Tchsp18.3 is expressed in all developmental stages, and is highly expressed at early pupal and late adult stages, while it is highly expressed in ovary and fat body at the adult period. Moreover, it was up-regulated 4532 ± 396-fold in response to enhanced heat stress but not to cold stress; meanwhile the lifespan of adults in ds-Tchsp18.3 group reduced by 15.8% from control group under starvation. Laval RNA interference (RNAi) of Tchsp18.3 caused 86.1% ± 4.5% arrested pupal eclosion and revealed that Tchsp18.3 played an important role in insect development. In addition, parental RNAi of Tchsp18.3 reduced the oviposition amount by 94.7%. These results suggest that Tchsp18.3 is not only essential for the resistance to heat and starvation stress, but also is critical for normal development and reproduction in T. castaneum.

Drosophila Hsp67Bc hot-spot variants alter muscle structure and function

The Drosophila Hsp67Bc gene encodes a protein belonging to the small heat-shock protein (sHSP) family, identified as the nearest functional ortholog of human HSPB8. The most prominent activity of sHSPs is preventing the irreversible aggregation of various non-native polypeptides. Moreover, they are involved in processes such as development, aging, maintenance of the cytoskeletal architecture and autophagy. In larval muscles Hsp67Bc localizes to the Z- and A-bands, which suggests its role as part of the conserved chaperone complex required for Z-disk maintenance. In addition, Hsp67Bc is present at neuromuscular junctions (NMJs), which implies its involvement in the maintenance of NMJ structure. Here, we report the effects of muscle-target overexpression of Drosophila Hsp67Bc hot-spot variants Hsp67BcR126E and Hsp67BcR126N mimicking pathogenic variants of human HSPB8. Depending on the substitutions, we observed a different impact on muscle structure and performance. Expression of Hsp67BcR126E affects larval motility, which may be caused by impairment of mitochondrial respiratory function and/or by NMJ abnormalities manifested by a decrease in the number of synaptic boutons. In contrast, Hsp67BcR126N appears to be an aggregate-prone variant, as reflected in excessive accumulation of mutant proteins and the formation of large aggregates with a lesser impact on muscle structure and performance compared to the Hsp67BcR126E variant.

Functional principles and regulation of molecular chaperones

To be able to perform their biological function, a protein needs to be correctly folded into its three dimensional structure. The protein folding process is spontaneous and does not require the input of energy. However, in the crowded cellular environment where there is high risk of inter-molecular interactions that may lead to protein molecules sticking to each other, hence forming aggregates, protein folding is assisted. Cells have evolved robust machinery called molecular chaperones to deal with the protein folding problem and to maintain proteins in their functional state. Molecular chaperones promote efficient folding of newly synthesized proteins, prevent their aggregation and ensure protein homeostasis in cells. There are different classes of molecular chaperones functioning in a complex interplay. In this review, we discuss the principal characteristics of different classes of molecular chaperones, their structure-function relationships, their mode of regulation and their involvement in human disorders.

Molecular characterization and expression of six heat shock protein genes in relation to development and temperature in Trichogramma chilonis

Trichogramma is a kind of egg parasitoid wasp that is widely used to control lepidopterous pests. Temperature is one of the main factors that determines the various life activities of this species, including development, reproduction and parasitism efficiency. Heat shock proteins (HSPs) are highly conserved and ubiquitous proteins that are best known for their responsiveness to temperature and other stresses. To explore the potential role of HSPs in Trichogramma species, we obtained the full-length cDNAs of six HSP genes (Tchsp10, Tchsp21.6, Tchsp60, Tchsp70, Tchsc70-3, and Tchsp90) from T. chilonis and analyzed their expression patterns during development and exposure to temperature stress. The deduced amino acid sequences of these HSP genes contained the typical signatures of their corresponding protein family and showed high homology to their counterparts in other species. The expression levels of Tchsp10, Tchsp21.6 and Tchsp60 decreased during development. However, the expression of Tchsc70-3 increased from the pupal stage to the adult stage. Tchsp70 and Tchsp90 exhibited the highest expression levels in the adult stage. The expression of six Tchsps was dramatically upregulated after 1 h of exposure to 32 and 40°C but did not significantly change after 1 h of exposure to 10 and 17°C. This result indicated that heat stress, rather than cold stress, induced the expression of HSP genes. Furthermore, the expression of these genes was time dependent, and the expression of each gene reached its peak after 1 h of heat exposure (40°C). Tchsp10 and Tchsp70 exhibited a low-intensity cold response after 4 and 8 h of exposure to 10°C, respectively, but the other genes did not respond to cold at any time points. These results suggested that HSPs may play different roles in the development of this organism and in its response to temperature stress.

Small heat shock proteins and neurodegeneration: recent developments

Members of the small heat shock protein (sHSP) family are molecular chaperones with a critical role in the maintenance of cellular homeostasis under unfavorable conditions. The chaperone properties of sHSPs prevent protein aggregation, and sHSP deregulation underlies the pathology of several diseases, including neurodegenerative disorders. Recent evidence suggests that the clientele of sHSPs is broad, and the mechanisms of sHSP-mediated neuroprotection diverse. Nonetheless, the crosstalk of sHSPs with the neurodegeneration-promoting signaling pathways remains poorly understood. Here, we survey recent findings on the role and regulation of sHSPs in neurodegenerative diseases.

Evolutionary Origins of Pax6 Control of Crystallin Genes

The birth of novel genes, including their cell-specific transcriptional control, is a major source of evolutionary innovation. The lens-preferred proteins, crystallins (vertebrates: α- and β/γ-crystallins), provide a gateway to study eye evolution. Diversity of crystallins was thought to originate from convergent evolution through multiple, independent formation of Pax6/PaxB-binding sites within the promoters of genes able to act as crystallins. Here, we propose that αB-crystallin arose from a duplication of small heat shock protein (Hspb1-like) gene accompanied by Pax6-site and heat shock element (HSE) formation, followed by another duplication to generate the αA-crystallin gene in which HSE was converted into another Pax6-binding site. The founding β/γ-crystallin gene arose from the ancestral Hspb1-like gene promoter inserted into a Ca2+-binding protein coding region, early in the cephalochordate/tunicate lineage. Likewise, an ancestral aldehyde dehydrogenase (Aldh) gene, through multiple gene duplications, expanded into a multigene family, with specific genes expressed in invertebrate lenses (Ω-crystallin/Aldh1a9) and both vertebrate lenses (η-crystallin/Aldh1a7 and Aldh3a1) and corneas (Aldh3a1). Collectively, the present data reconstruct the evolution of diverse crystallin gene families.

Ultraviolet filters and heat shock proteins: effects in Chironomus riparius by benzophenone-3 and 4-methylbenzylidene camphor

Benzophenone-3 (BP3) and 4-methylbenzylidene camphor (4MBC) are common ultraviolet filters (UV filters), compounds considered as emergent contaminants, used in different products like plastics and personal care products. The levels of these compounds are rising in the wild, but the effects they have on invertebrates are poorly understood. Chironomus riparius is a benthic insect widely used in toxicology, and several studies have been previously performed in our laboratory to determine the effects these compounds have on this organism at the molecular level. We have shown that UV filters can alter the mRNA levels of heat shock protein 70 (Hsp70), one of the most studied heat shock proteins. Although these proteins are crucial for the survival of organisms, little data is available on the effects these emergent contaminants have on them, especially in invertebrates. Here, we analyzed the transcriptional activity of 12 genes covering the different groups of heat shock protein [Hsp10, Hsp17, Hsp21, Hsp22, Hsp23, Hsp24, Hsp27, Hsp34, Hsp40, Hsp60, Hsc70 (3), and Hsc70 (4)] in response to 0.1 and 1 mg/L concentrations of BP3 and 4MBC at 8 and 24 h. The results showed that some small Hsp (sHsp) genes were altered by these compounds, while the genes of proteins present in mitochondria, Hsp10 and Hsp60, did not change. sHsps are also involved in developmental processes, so the observed variations could be due to the endocrine disruption activity described for these compounds rather than to a stress response.

Identification and expression analysis of multiple small heat shock protein genes in spruce budworm, Choristoneura fumiferana (L.)

Fifteen small heat shock protein (sHSP) genes were identified from spruce budworm, Choristoneura fumiferana (L.), an important native forest pest in North America. The transcript levels of each CfHSP were measured under non-stress conditions in all life stages from egg to adult and in five different larval tissues. CfHSP transcript levels showed variation during development, with highest levels in adults and lowest in eggs. Most CfHSP transcripts are highly expressed in larval fat body and Malpighian tubules; two CfHSPs display extremely high expression in the head and epidermis. Upon heat stress, nine CfHSP genes are significantly upregulated, increasing by 50- to 2500-fold depending on developmental stage and tissue type. Upon starvation, eight CfHSPs are upregulated or downregulated, whereas six others retain constant expression. These results suggest that CfHSPs have important and multiple roles in spruce budworm development and in response to heat stress and starvation.

Characteristics and expression of genes encoding two small heat shock protein genes lacking introns from Chilo suppressalis

Small heat shock proteins (sHSPs) constitute a large, diverse, and functionally uncharacterized family of heat shock proteins. To gain insight regarding the function of sHSPs in insects, we identified genes encoding two sHSPs, Cshsp22.9b and Cshsp24.3, from the rice pest Chilo suppressalis. The cDNAs of Cshsp22.9b and Cshsp24.3 encoded proteins of 206 and 216 amino acids with isoelectric points of 5.79 and 9.28, respectively. Further characterization indicated that both Cshsp22.9b and Cshsp24.3 lacked introns. Real-time quantitative PCR indicated that Cshsp22.9b and Cshsp24.3 were expressed at higher levels within the fat body as compared to other tissues (head, epidermis, foregut, midgut, hindgut, Malpighian tubules, and hemocytes). Expression of Cshsp22.9b and Cshsp24.3 was lowest in the hindgut and Malpighian tubules, respectively. Cshsp22.9b and Cshsp24.3 showed identical patterns in response to thermal stress from -11 to 43 °C, and both genes were up-regulated by hot and cold temperatures. The mRNA (messenger ribonucleic acid) expression levels of Cshsp22.9b (KY701308) and Cshsp24.3 (KY701309) were highest after a 2-h exposure at 39 °C and started to decline at 42 °C. In response to cold temperatures, both Cshsp22.9b and Cshsp24.3 showed maximal expression after a 2-h exposure to -3 °C. The two Cshsps were more responsive to hot than cold temperature stress and were not induced by mildly cold or warm temperatures. In conclusion, Cshsp22.9b and Cshsp24.3 could play a very important role in the regulation of physiological activities in C. suppressalis that are impacted by environmental stimuli.