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BACKGROUND: The widespread use of glyphosate has many adverse effects on Apis cerana cerana. Due to the incomplete understanding of the molecular mechanisms of glyphosate toxicity, there are no available methods for mitigating the threat of glyphosate to Apis cerana cerana. Small heat shock proteins (sHSPs) play an important role in resisting oxidative stress, but their mechanism of action in Apis cerana cerana remains unclear. RESULTS: In this experiment, we cloned and identified AccsHSP21.7. Studies have shown that AccsHSP21.7 contains binding motifs for various transcription factors related to oxidative stress. Abiotic stresses induced the expression of AccsHSP21.7. Bacteriostatic testing of a recombinant AccsHSP21.7 protein proved that Escherichia coli overexpressing AccsHSP21.7 showed increased resistance to oxidative stress. Knocking down the AccsHSP21.7 gene caused significant damage to midgut cells, which seriously disrupted the antioxidant system in Apis cerana cerana and greatly increased mortality under glyphosate stress. CONCLUSION: This study investigated the relationship between antioxidant regulation and the AccsHSP21.7 gene at the molecular level, and the results have guiding significance for the improvement of stress resistance in Apis cerana cerana. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

The small heat shock proteins (sHSPs), whose molecular weight ranges from 12∼43 kDa, are members of the heat shock protein (HSP) family that are widely found in all organisms. As intracellular stress resistance molecules, sHSPs play an important role in maintaining the homeostasis of the intracellular environment under various stressful conditions. A total of 10 sHSPs have been identified in mammals, sharing conserved α-crystal domains combined with variable N-terminal and C-terminal regions. Unlike large-molecular-weight HSP, sHSPs prevent substrate protein aggregation through an ATP-independent mechanism. In addition to chaperone activity, sHSPs were also shown to suppress apoptosis, ferroptosis, and senescence, promote autophagy, regulate cytoskeletal dynamics, maintain membrane stability, control the direction of cellular differentiation, modulate angiogenesis, and spermatogenesis, as well as attenuate the inflammatory response and reduce oxidative damage. Phosphorylation is the most significant post-translational modification of sHSPs and is usually an indicator of their activation. Furthermore, abnormalities in sHSPs often lead to aggregation of substrate proteins and dysfunction of client proteins, resulting in disease. This paper reviews the various biological functions of sHSPs in mammals, emphasizing the roles of different sHSPs in specific cellular activities. In addition, we discuss the effect of phosphorylation on the function of sHSPs and the association between sHSPs and disease. [ABSTRACT FROM AUTHOR]

The HspB8‐BAG3 complex plays an important role in the protein quality control acting alone or within multi‐components complexes. To clarify the mechanism underlying its activity, in this work we used biochemical and biophysical approaches to study the tendency of both proteins to auto‐assemble and to form the complex. Solubility and Thioflavin T assays, Fourier transform infrared spectroscopy and atomic force microscopy analyses clearly showed the tendency of HspB8 to self‐assemble at high concentration and to form oligomers in a "native‐like" conformation; otherwise, BAG3 aggregates poorly. Noteworthy, also HspB8 and BAG3 associate in a "native‐like" conformation, forming a stable complex. Furthermore, the high difference between dissociation constant values of HspB8‐HspB8 interaction with respect to the binding to BAG3 obtained by surface plasmon resonance confirms that HspB8 is an obligated partner of BAG3 in vivo. Lastly, both proteins alone or in the complex are able to bind and affect the aggregation of the Josephin domain, the structured domain that triggers the ataxin‐3 fibrillation. In particular, the complex displayed higher activity than HspB8 alone. All this considered, we can assert that the two proteins form a stable assembly with chaperone‐like activity that could contribute to the physiological role of the complex in vivo. [ABSTRACT FROM AUTHOR]

Bacteriophage ϕX174 is a small icosahedral virus of the Microviridae with a rapid replication cycle. Previously, we found that in ϕX174 infections of Escherichia coli , the most highly upregulated host proteins are two small heat shock proteins, IbpA and IbpB, belonging to the HSP20 family, which is a universally conserved group of stress-induced molecular chaperones that prevent irreversible aggregation of proteins. Heat shock proteins were found to protect against ϕX174 lysis, but IbpA/B have not been studied. In this work, we disrupted the ibpA and ibpB genes and measured the effects on ϕX174 replication. We found that in contrast to other E. coli heat shock proteins, they are not necessary for ϕX174 replication; moreover, their absence has no discernible effect on ϕX174 fecundity. These results suggest IbpA/B upregulation is a response to ϕX174 protein expression but does not play a role in phage replication, and they are not Microviridae host factors. • Small heat shock protein genes ibpAB are collectively non-essential for phiX174 replication. • Individual ibpA or ibpB gene knockouts in E. coli C result in heat sensitivity at 45 °C. • In contrast to K-12 strain backgrounds, the ibpAB genes may be collectively essential for E. coli C strains. [ABSTRACT FROM AUTHOR]

Cherax quadricarinatus has been widely introduced and cultured around the world and has been seriously affected by pathogens, including viruses and bacteria. Small heat shock proteins (sHsps) have been shown to have a positive effect on immune responses in animals. In this study, three subunits of sHsps (CqsHsps, named CqHsp24.06, CqHsp41.97 and CqHsp40.17) from C. quadricarinatus were cloned. The coding sequence lengths of the CqHsp24.06, CqHsp41.97 and CqHsp40.17 genes were 654 bp, 1128 bp and 1074 bp, with a molecular weight of 24.06, 41.97 and 40.17 kDa, respectively. In normal tissues, the expression level of CqHsp24.06 was the highest in the intestinal tract and was 12 times higher than that in the hepatopancreas, while CqHsp41.97 was mostly expressed in the gills which was 8 times higher than that in the nerves. However, CqHsp40.17 was highest in the nerves and was 12 times higher than its expression level in the gonads. In gills of C. quadricarinatus stressed by Vibrio Alginolyticus, the relative expression levels of CqHsp24.06, CqHsp41.97 and CqHsp40.17 in gill first increased and then decreased, and the maximum expression increased by 25 times. Under Aeromonas hydrophila stress, the expression of CqHsp24.06 and CqHsp41.97 reached the highest level at the 3‐h time point and at the 12‐h time point for CqHsp40.17, and the maximum expression increased by 3.5 times. These results indicated that CqsHsps could induce the activation of the immune system, and they were more sensitive to Vibrio Alginolyticus than to Aeromonas hydrophila. [ABSTRACT FROM AUTHOR]

The small heat shock proteins (sHSPs), whose molecular weight ranges from 12∼43 kDa, are members of the heat shock protein (HSP) family that are widely found in all organisms. As intracellular stress resistance molecules, sHSPs play an important role in maintaining the homeostasis of the intracellular environment under various stressful conditions. A total of 10 sHSPs have been identified in mammals, sharing conserved α-crystal domains combined with variable N-terminal and C-terminal regions. Unlike large-molecular-weight HSP, sHSPs prevent substrate protein aggregation through an ATP-independent mechanism. In addition to chaperone activity, sHSPs were also shown to suppress apoptosis, ferroptosis, and senescence, promote autophagy, regulate cytoskeletal dynamics, maintain membrane stability, control the direction of cellular differentiation, modulate angiogenesis, and spermatogenesis, as well as attenuate the inflammatory response and reduce oxidative damage. Phosphorylation is the most significant post-translational modification of sHSPs and is usually an indicator of their activation. Furthermore, abnormalities in sHSPs often lead to aggregation of substrate proteins and dysfunction of client proteins, resulting in disease. This paper reviews the various biological functions of sHSPs in mammals, emphasizing the roles of different sHSPs in specific cellular activities. In addition, we discuss the effect of phosphorylation on the function of sHSPs and the association between sHSPs and disease.

Small heat shock proteins as large multigene family are present ubiquitously among Archaea to Eukaryota. The sHSPs are molecular chaperones that maintain the proper protein folding and disaggregation of denatured proteins during stress conditions. In the present study, out of identified 38 sHSPs in the pigeonpea genome, the 20 are distributed across seven chromosomes while the remaining are located on unassembled scaffolds. These Cc_sHSPs are classified into 16 subfamilies. The cytoplasmic class-II is the largest sub-family with five Cc_sHSPs. The gene structure analysis revealed that Cc_sHSP genes specifically containing no or very few introns. The promoter analysis revealed the presence of various cis -acting elements responsible for developmental, biotic, and abiotic stress specific-induction of Cc_sHSPs. A total of one segmental duplication and four tandem duplication events are identified for Cc_sHSPs. The qRT-PCR based expression analysis of all 38 Cc_sHSP genes was conducted for diverse abiotic stress conditions. The Cc_sHSP genes are highly induced by heat, drought, cold, and salt stresses indicating a key role in mitigating the various abiotic stress responses. The divergence time of paralogous Cc_sHSPs ranged from 8.66 to 191.82 MYA. The present study can be a strong basis for the functional characterization of Cc_sHSPs. [ABSTRACT FROM AUTHOR]

Small heat shock proteins (sHSPs) are a very complex protein superfamily that increase insect temperature tolerance. In order to deeply understand the function and role of sHSPs in Chilo suppressalis (Walker), this study isolated and identified two CsHSP genes lacking introns from C. suppressalis, Cshsp23.9 and Cshsp27.3. The cDNA full-length of Cshsp23.9 and Cshsp27.3 were 909 and 1 036 bp encoding 220 and 242 amino acids, respectively. Alignment with homologs and phylogenetic analysis indicated Cshsp23.9 and Cshsp27.3 were two new types of Cshsps in C. suppressalis. Real-time quantitative PCR (qPCR) revealed that Cshsp23.9 had the highest relative expression in hindgut compared with other tissues (head, epidermis, foregut, midgut, fat body, Malpighian tubules, and hemocytes), while Cshsp27.3 expressed the highest in fat body content. When exposed to thermal stress from −11 to 43°C for 2 h, two genes showed different expression patterns. Cshsp23.9 did not respond to low temperature, but could be up-regulated by high temperature and the highest expression temperature was at 36°C. Cshsp27.3 could only be induced by mild temperature, with the highest expression at 15 and 30°C. In conclusion, Cshsp23.9 and Cshsp27.3 existed in different tissues/organs of C. suppressalis, and played different important roles in C. suppressalis to resist temperature stress and regulate physiological activities.

Adenosine triphosphate (ATP) is an important fuel of life for humans and Mycobacterium species. Its potential role in modulating cellular functions and implications in systemic, pulmonary, and ocular diseases is well studied. Plasma ATP has been used as a diagnostic and prognostic biomarker owing to its close association with disease’s progression. Several stresses induce altered ATP generation, causing disorders and illnesses. Small heat shock proteins (sHSPs) are dynamic oligomers that are dominantly β-sheet in nature. Some important functions that they exhibit include preventing protein aggregation, enabling protein refolding, conferring thermotolerance to cells, and exhibiting anti-apoptotic functions. Expression and functions of sHSPs in humans are closely associated with several diseases like cataracts, cardiovascular diseases, renal diseases, cancer, etc. Additionally, there are some mycobacterial sHSPs like Mycobacterium leprae HSP18 and Mycobacterium tuberculosis HSP16.3, whose molecular chaperone functions are implicated in the growth and survival of pathogens in host species. As both ATP and sHSPs, remain closely associated with several human diseases and survival of bacterial pathogens in the host, therefore substantial research has been conducted to elucidate ATP-sHSP interaction. In this mini review, the impact of ATP on the structure and function of human and mycobacterial sHSPs is discussed. Additionally, how such interactions can influence the onset of several human diseases is also discussed.

In this mini-review, we summarize the known and novel regulation mechanisms of small heat shock proteins (sHsps). sHsps belong to a well-conserved family of ATP-independent oligomeric chaperones that protect denatured proteins from forming irreversible aggregates by co-aggregation. The functions of sHsps as a first line of defense against acute stresses require the high abundance of sHsps on demand. The heat stress-induced expression of IbpA, one of the sHsps in Escherichia coli, is regulated by σ32, an RNA polymerase subunit, and the thermoresponsive mRNA structures in the 5′ untranslated region, called RNA thermometers. In addition to the known mechanisms, a recent study has revealed unexpected processes by which the oligomeric IbpA self-represses the ibpA translation via the direct binding of IbpA to its own mRNA, and mediates the mRNA degradation. In summary, the role of IbpA as an aggregation-sensor, combined with other mechanisms, tightly regulates the expression level of IbpA, thus enabling the sHsp to function as a "sequestrase" upon acute aggregation stress, and provides new insights into the mechanisms of other sHsps in both bacteria and eukaryotes. [ABSTRACT FROM AUTHOR]

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 (5th 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 proteins (sHSPs) are important modulators of insect survival. Previous research revealed that there is only one orthologous cluster of shsps in insects. Here, we identified another novel orthologous cluster of shsps in insects by comparative analysis. Multiple stress experiments and function investigation of Tchsp21.8a belonging to this orthologous cluster and seven species-specific shsps were performed in the stored-grain pest Tribolium castaneum. The results indicated that expression of Tchsp21.8a showed weak responses to different stresses. However, expressions of most species-specific shsps exhibited hyper-responses to heat stress, and expressions of all species-specific shsps displayed diverse responses during other stresses to protect beetles in a cooperative manner. Additionally, Tchsp21.8a and species-specific Tcshsp19.7 played important roles in the development of T. castaneum , and all Tcshsps had a certain impact on the fecundity. Our work created a comprehensive reliable scaffold of insect shsps that can further provide instructive insights to pest bio-control • Firstly identified another novel orthologous cluster of sHSPs in insects. • Two shsps were identified in Acrythociphon pisum and one new shsp was found in Anopheles gambiae. • Novel orthologous Tchsp21.8a in Tribolium castaneum had typical features of orthologous shsps. • Most species-specific Tcshsps were related to anti-heat stress by hundreds-fold up-regulation. • Species-specific Tcshsps did not respond to cold but had different responses under other stresses. [ABSTRACT FROM AUTHOR]

Abstract Objective During muscle development or regeneration, myocytes produce nerve growth factor (NGF) as well as its tyrosine-kinase and p75-neurotrophin (p75NTR) receptors. It has been published that the p75NTR receptor could represent a key regulator of NGF-mediated myoprotective effect on satellite cells, but the precise function of NGF/p75 signaling pathway on myogenic cell proliferation, survival and differentiation remains fragmented and controversial. Here, we verified the role of NGF in the growth, survival and differentiation of p75NTR-expressing L6C5 myogenic cells, specifically inquiring for the putative involvement of the nuclear factor κB (NFκB) and the small heat shock proteins (sHSPs) αB-crystallin and Hsp27 in these processes. Results Although NGF was not effective in modulating myogenic cell growth or survival in both standard or stress conditions, we demonstrated for the first time that, under serum deprivation, NGF sustained the activity of some key enzymes involved in energy metabolism. Moreover, we confirmed that NGF promotes myogenic fusion and expression of the structural protein myosin heavy chain while modulating NFκB activation and the content of sHSPs correlated with the differentiation process. We conclude that p75NTR is sufficient to mediate the modulation of L6C5 myogenic differentiation by NGF in term of structural, metabolic and functional changes.

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.

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.

Human small heat shock proteins are molecular chaperones that regulate fundamental cellular processes in normal and pathological cells. Here, we have reviewed the role played by HspB1, HspB4 and HspB5 in the context of Cystic Fibrosis (CF), a severe monogenic autosomal recessive disease linked to mutations in Cystic Fibrosis Transmembrane conductance Regulator protein (CFTR) some of which trigger its misfolding and rapid degradation, particularly the most frequent one, F508del-CFTR. While HspB1 and HspB4 favor the degradation of CFTR mutants, HspB5 and particularly one of its phosphorylated forms positively enhance the transport at the plasma membrane, stability and function of the CFTR mutant. Moreover, HspB5 molecules stimulate the cellular efficiency of currently used CF therapeutic molecules. Different strategies are suggested to modulate the level of expression or the activity of these small heat shock proteins in view of potential in vivo therapeutic approaches. We then conclude with other small heat shock proteins that should be tested or further studied to improve our knowledge of CFTR processing.

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. [ABSTRACT FROM AUTHOR]

Today, one of the main objectives of agricultural biotechnology area is to find the responsible genes involved in stress response and engineering these genes to improve the plant response mechanisms. Therefore the current study was conducted to gain an insight on the role of HSP17.7 gene, which is a member of sHsps family, in defence mechanism of sunflower (Helianthus annuus L. cv. Confeta -Turkish cultivar) treated with different doses of UVA and UVB (4, 8, 12 and 20 kJ/m2) and concentrations of copper (Cu2+) and zinc (Zn2+) (80, 160, 320, 640, and 1280 µM) heavy metals. Based on our data, it was observed that different doses of UVA and UVB irradiation resulted in increased levels of HSP17.7 mRNA in sunflower plants. The highest levels of these increases (8 and 12 kJ/m2 of UVA) were seen under UVA stress. In contrast to UV stress, only the Cu2+concentration of 1280 µM led to higher expression levels of HSP17.7 gene compared to the control. Besides this, the 1280 µM concentration of Zn2+ treatment was the peak point of increased HSP17.7 mRNA levels for all stress conditions with nearly 8 times more than in the control sample. Negative correlations were found between malondialdehyde (MDA) levels and expression levels of HSP17.7 gene in sunflower plants subjected to current abiotic stress conditions. This correlation might indicate that an effective defence mechanism was in action and it might be concluded that the HSP17.7 gene can be used for identification of cultivars tolerant to UV and high doses of Cu2+ and Zn2+ for molecular breeding studies in the near future. These findings provide evidence of the HSP17.7 gene contribution to abiotic stress response in sunflower and will be helpful for the next studies about stress tolerance improvement in sunflower plants.

Small heat shock proteins (sHSPs) are ubiquitous ATP-independent chaperones that play essential roles in response to cellular stresses and protein homeostasis. Investigations of sHSPs reveal that sHSPs are ubiquitously expressed in numerous types of tumors, and their expression is closely associated with cancer progression. sHSPs have been suggested to control a diverse range of cancer functions, including tumorigenesis, cell growth, apoptosis, metastasis, and chemoresistance, as well as regulation of cancer stem cell properties. Recent advances in the field indicate that some sHSPs have been validated as a powerful target in cancer therapy. In this review, we present and highlight current understanding, recent progress, and future challenges of sHSPs in cancer development and therapy.

Small heat shock proteins (sHSPs) are ubiquitous stress proteins that are able to protect the cells against cellular insults from temperature, heavy metal etc. However, the molecular chaperone roles of sHSPs in enhancing growth and adaptation under combined temperature and metal stresses in Escherichia coli cells have been poorly understood. Here, we analyze the function of recombinant AgsA, a small heat shock protein from Salmonella enterica serovar Typhimurium under combined temperature and zinc stress in E. coli . Our results show that the heterologous expression of AgsA significantly increases the tolerance of E. coli cells to the combined effect of temperature stress and zinc toxicity by maintaining the stability of soluble proteins. Furthermore, there was remarkable and significant difference in the half effect concentration (EC50) of zinc at all temperatures treatments in both test cells. The EC50s of zinc at 37 °C, 42 °C and 50 °C were 15.24 mg/L, 29.30 mg/L, and 5.98 mg/L respectively in the AgsA-transformed E. coli cells, and 3.03 mg/L, 2.38 mg/L, and 0.373 mg/L, respectively in the control cells lacking AgsA. Together, our data indicate a good concentration-response relationship between all three temperatures treatment and zinc toxicity in E. coli, and establish for the first time the combined effects of temperature and zinc toxicity on E. coli cells. Also, the AgsA protein response to combined thermal and metal stress could serve as a molecular biomarker for the assessment of interactive stress damage to the cells. [ABSTRACT FROM AUTHOR]

Objective: During muscle development or regeneration, myocytes produce nerve growth factor (NGF) as well as its tyrosine-kinase and p75-neurotrophin (p75NTR) receptors. It has been published that the p75NTR receptor could represent a key regulator of NGF-mediated myoprotective effect on satellite cells, but the precise function of NGF/p75 signaling pathway on myogenic cell proliferation, survival and differentiation remains fragmented and controversial. Here, we verified the role of NGF in the growth, survival and differentiation of p75NTR- expressing L6C5 myogenic cells, specifically inquiring for the putative involvement of the nuclear factor δB (NFδB) and the small heat shock proteins (sHSPs) αB-crystallin and Hsp27 in these processes. Results: Although NGF was not effective in modulating myogenic cell growth or survival in both standard or stress conditions, we demonstrated for the first time that, under serum deprivation, NGF sustained the activity of some key enzymes involved in energy metabolism. Moreover, we confirmed that NGF promotes myogenic fusion and expression of the structural protein myosin heavy chain while modulating NFδB activation and the content of sHSPs correlated with the differentiation process. We conclude that p75NTR is sufficient to mediate the modulation of L6C5 myogenic differentiation by NGF in term of structural, metabolic and functional changes. [ABSTRACT FROM AUTHOR]

Small heat shock proteins ( sHsps) are an evolutionary conserved class of ATP-independent chaperones that protect cells against proteotoxic stress. sHsps form assemblies with aggregation-prone misfolded proteins, which facilitates subsequent substrate solubilization and refolding by ATP-dependent Hsp70 and Hsp100 chaperones. Substrate solubilization requires disruption of sHsp association with trapped misfolded proteins. Here, we unravel a specific interplay between Hsp70 and sHsps at the initial step of the solubilization process. We show that Hsp70 displaces surface-bound sHsps from sHsp-substrate assemblies. This Hsp70 activity is unique among chaperones and highly sensitive to alterations in Hsp70 concentrations. The Hsp70 activity is reflected in the organization of sHsp-substrate assemblies, including an outer dynamic sHsp shell that is removed by Hsp70 and a stable core comprised mainly of aggregated substrates. Binding of Hsp70 to the sHsp/substrate core protects the core from aggregation and directs sequestered substrates towards refolding pathway. The sHsp/Hsp70 interplay has major impact on protein homeostasis as it sensitizes substrate release towards cellular Hsp70 availability ensuring efficient refolding of damaged proteins under favourable folding conditions. [ABSTRACT FROM AUTHOR]

Cadmium (Cd) is a widespread and highly toxic heavy metal of particular ecotoxicological relevance for aquatic ecosystems. It occurs naturally in the environment but is also an industrial pollutant with extensively researched carcinogenic potentials. Heat shock proteins (HSPs) are chaperones that play an important role in maintaining protein homeostasis under stress conditions. Small heat shock proteins (sHSPs) comprise the most diverse group of the HSPs family. They are expressed both constitutively and by stress-induction. The midge Chironomus riparius is widely used as a test species in aquatic toxicology. In the present study, Reverse Transcription Polymerase Chain Reaction (RT-PCR) was used to evaluate the effects of acute Cd exposure to the expression profile of seven shsp genes ( hsp17, hsp21 , hsp22 , hsp23 , hsp24 , hsp27 , and hsp34) in C. riparius larvae. Results show a specific pattern of response with a rapid response by hsp27 , which was downregulated at 2–6 h, while the rest of the shsp genes remained unaltered except for hsp17 at 2 h, which was upregulated. However, at 24 h of exposure are observed high levels of hsp23 , hsp24 , hsp27 , and hsp34 transcription while hsp22 mRNA levels were downregulated and hsp17 and hsp21 remained unaltered. These changes in gene expression suggest a functional diversity between the sHSPs in the cellular response to heavy metal stress. The differential pattern in comparison with heat shock supports a specific profile depending on the stress supporting the use of shsp genes as suitable biomarkers for ecotoxicological studies on aquatic systems. [ABSTRACT FROM AUTHOR]

The HspB8-BAG3 complex plays an important role in the protein quality control acting alone or within multi-components complexes. To clarify the mechanism underlying its activity, in this work we used biochemical and biophysical approaches to study the tendency of both proteins to auto-assemble and to form the complex. Solubility and Thioflavin T assays, Fourier transform infrared spectroscopy and atomic force microscopy analyses clearly showed the tendency of HspB8 to self-assemble at high concentration and to form oligomers in a "native-like" conformation; otherwise, BAG3 aggregates poorly. Noteworthy, also HspB8 and BAG3 associate in a "native-like" conformation, forming a stable complex. Furthermore, the high difference between dissociation constant values of HspB8-HspB8 interaction with respect to the binding to BAG3 obtained by surface plasmon resonance confirms that HspB8 is an obligated partner of BAG3 in vivo. Lastly, both proteins alone or in the complex are able to bind and affect the aggregation of the Josephin domain, the structured domain that triggers the ataxin-3 fibrillation. In particular, the complex displayed higher activity than HspB8 alone. All this considered, we can assert that the two proteins form a stable assembly with chaperone-like activity that could contribute to the physiological role of the complex in vivo., (© 2023 The Authors. Protein Science published by Wiley Periodicals LLC on behalf of The Protein Society.)

Fusarium verticillioides is the most commonly reported fungal species responsible for ear rot of maize which substantially reduces grain yield. It also results in a substantial accumulation of mycotoxins that give rise to toxic response when ingested by animals and humans. For inefficient control by chemical and agronomic measures, it thus becomes more desirable to select more resistant varieties. However, the molecular mechanisms underlying the infection process remain poorly understood, which hampers the application of quantitative resistance in breeding programs. Here, we reveal the disease-resistance mechanism of the maize inbred line of BT-1 which displays high resistance to ear rot using RNA high throughput sequencing. By analyzing RNA-seq data from the BT-1 kernels before and after F. verticillioides inoculation, we found that transcript levels of genes associated with key pathways are dramatically changed compared with the control treatment. Differential gene expression in ear rot resistant and susceptible maize was confirmed by RNA microarray and qRT-PCR analyses. Further investigation suggests that the small heat shock protein family, some secondary metabolites, and the signaling pathways of abscisic acid (ABA), jasmonic acid (JA) or salicylic acids (SA) may be involved in the pathogen-associated molecular pattern-triggered immunity against F. verticillioides. These data will not only provide new insights into the molecular resistant mechanisms against fungi invading, but may also result in the identification of key molecular factors associated with ear rot resistance in maize.

The α-crystallin domain (ACD) is an ancient domain conserved among all kingdoms. Plant ACD proteins have roles in abiotic stresses, transcriptional regulation, inhibiting virus movement and DNA demethylation. An exhaustive in-silico analysis using Hidden Markof Model-based conserved motif search of the tomato proteome yielded a total of 50 ACD proteins that belonged to 4 groups, sub-divided further into18 classes. One of these groups belongs to the small heat shock protein (sHSP) class of proteins, molecular chaperones implicated in heat tolerance. Both tandem and segmental duplication events appear to have shaped the expansion of this gene family with purifying selection being the primary driving force for evolution. The expression profiling of the Acd genes in two different heat stress regimes suggested that their transcripts are differentially regulated with roles in acclimation and adaptive response during recovery. The co-expression of various genes in response to different abiotic stresses (heat, low temperature, dehydration, salinity and oxidative stress) and phytohormones (abscisic acid and salicylic acid) suggested possible cross-talk between various members to combat a myriad of stresses. Further, several genes were highly expressed in fruit, root and flower tissues as compared to leaf signifying their importance in plant development too. Evaluation of the expression of this gene family in field grown tissues highlighted the prominent role they have in providing thermo-tolerance during daily temperature variations. The function of three putative sHSPs was established as holdase chaperones as evidenced by protection to malate-dehydrogenase against heat induced protein-aggregation. This study provides insights into the characterization of the Acd genes in tomato and forms the basis for further functional validation in-planta.

Small heat shock proteins (sHSPs), the intra cellular chaperons respond to high temperatures and other stresses, are expressed under the control of the heat shock factors, which recognize highly conserved cis-regulatory elements (CREs). The present study was designed to identify and compare nine different sHSP gene promoters from rice on the basis of their location on chromosomes, sequence similarities, evolutionary relationship and putative binding sites of transcription factors. Additionally, they were analyzed for their functional importance in the regulation of sHSP genes. For this, 5′ upstream region of nine sHSP genes from Oryza sativa was amplified, sequenced and analyzed. RFLP mapping approach using molecular linkage maps of three-way cross-population showed that OsHSP 16.9A, OsHSP 16.9B, OsHSP 16.9C and OsHSP C-II genes were clustered on the short arm of chromosome 1 with a 1238-bp overlapped sequence between OsHSP 16.9A and OsHSP 16.9B, whereas OsHSP 17.3, OsHSP 17.7, OsHSP 17.9, OsHSP 18.0 and OsHSP 26 genes were clustered on chromosome 3 with a 420-bp overlapped sequence between OsHSP 17.3 and OsHSP 18.0. Evolutionary analysis revealed that sHSPs that clustered on different chromosomes in the same specie showed high sequence similarity and evolved prior to the divergence of their localization. Eighteen CREs remained conserved among all sHSP gene promoters during evolution. These common regulatory elements are related to disease resistance, hormonal responses, light responses, seed storage proteins, tissue-specific expression, pollen development and other environmental stresses. Moreover, CCAATBOX1 was also found in all sHSP gene promoters involved in the regulation of heat shock response. Conclusively, promoter region of sHSP genes seems to be capable of driving genes expression during stress and genetic manipulation might be helpful in producing better quality rice. [ABSTRACT FROM AUTHOR]

Small heat shock proteins (sHSPs) have been shown to be involved in stress tolerance. However, their functions in Prunus mume under heat treatment are poorly characterized. To improve our understanding of sHSPs, we cloned a sHSP gene, PmHSP17.9, from P. mume. Sequence alignment and phylogenetic analysis indicated that PmHSP17.9 was a member of plant cytosolic class III sHSPs. Besides heat stress, PmHSP17.9 was also upregulated by salt, dehydration, oxidative stresses and ABA treatment. Leaves of transgenic Arabidopsis thaliana that ectopically express PmHSP17.9 accumulated less O and HO compared with wild type (WT) after 42 °C treatment for 6 h. Over-expression of PmHSP17.9 in transgenic Arabidopsis enhanced seedling thermotolerance by decreased relative electrolyte leakage and MDA content under heat stress treatment when compared to WT plants. In addition, the induced expression of HSP101, HSFA2, and delta 1-pyrroline-5-carboxylate synthase ( P5CS) under heat stress was more pronounced in transgenic plants than in WT plants. These results support the positive role of PmHSP17.9 in response to heat stress treatment. [ABSTRACT FROM AUTHOR]

Today, one of the main objectives of agricultural biotechnology area is to find the responsible genes involved in stress response and engineering these genes to improve the plant response mechanisms. Therefore the current study was conducted to gain an insight on the role of HSP17.7 gene, which is a member of sHsps family, in defence mechanism of sunflower (Helianthus annuus L. cv. Confeta -- Turkish cultivar) treated with different doses of UVA and UVB (4, 8, 12 and 20 kJ/m²) and concentrations of copper (Cu2+) and zinc (Zn2+) (80, 160, 320, 640, and 1280 µM) heavy metals. Based on our data, it was observed that different doses of UVA and UVB irradiation resulted in increased levels of HSP17.7 mRNA in sunflower plants. The highest levels of these increases (8 and 12 kJ/m² of UVA) were seen under UVA stress. In contrast to UV stress, only the Cu2+concentration of 1280 µM led to higher expression levels of HSP17.7 gene compared to the control. Besides this, the 1280 µM concentration of Zn2+ treatment was the peak point of increased HSP17.7 mRNA levels for all stress conditions with nearly 8 times more than in the control sample. Negative correlations were found between malondialdehyde (MDA) levels and expression levels of HSP17.7 gene in sunflower plants subjected to current abiotic stress conditions. This correlation might indicate that an effective defence mechanism was in action and it might be concluded that the HSP17.7 gene can be used for identification of cultivars tolerant to UV and high doses of Cu2+ and Zn2+ for molecular breeding studies in the near future. These findings provide evidence of the HSP17.7 gene contribution to abiotic stress response in sunflower and will be helpful for the next studies about stress tolerance improvement in sunflower plants. [ABSTRACT FROM AUTHOR]

The α-crystallin domain (ACD) is an ancient domain conserved among all kingdoms. Plant ACD proteins have roles in abiotic stresses, transcriptional regulation, inhibiting virus movement, and DNA demethylation. An exhaustive in-silico analysis using Hidden Markov Model-based conserved motif search of the tomato proteome yielded a total of 50 ACD proteins that belonged to four groups, sub-divided further into 18 classes. One of these groups belongs to the small heat shock protein (sHSP) class of proteins, molecular chaperones implicated in heat tolerance. Both tandem and segmental duplication events appear to have shaped the expansion of this gene family with purifying selection being the primary driving force for evolution. The expression profiling of the Acd genes in two different heat stress regimes suggested that their transcripts are differentially regulated with roles in acclimation and adaptive response during recovery. The co-expression of various genes in response to different abiotic stresses (heat, low temperature, dehydration, salinity, and oxidative stress) and phytohormones (abscisic acid and salicylic acid) suggested possible cross-talk between various members to combat a myriad of stresses. Further, several genes were highly expressed in fruit, root, and flower tissues as compared to leaf signifying their importance in plant development too. Evaluation of the expression of this gene family in field grown tissues highlighted the prominent role they have in providing thermo-tolerance during daily temperature variations. The function of three putative sHSPs was established as holdase chaperones as evidenced by protection to malate-dehydrogenase against heat induced protein-aggregation. This study provides insights into the characterization of the Acd genes in tomato and forms the basis for further functional validation in-planta. [ABSTRACT FROM AUTHOR]

Molecular chaperones control the cellular folding, assembly, unfolding, disassembly, translocation, activation, inactivation, disaggregation, and degradation of proteins. In 1989, groundbreaking experiments demonstrated that a purified chaperone can bind and prevent the aggregation of artificially unfolded polypeptides and use ATP to dissociate and convert them into native proteins. A decade later, other chaperones were shown to use ATP hydrolysis to unfold and solubilize stable protein aggregates, leading to their native refolding. Presently, the main conserved chaperone families Hsp70, Hsp104, Hsp90, Hsp60, and small heat-shock proteins (sHsps) apparently act as unfolding nanomachines capable of converting functional alternatively folded or toxic misfolded polypeptides into harmless protease-degradable or biologically active native proteins. Being unfoldases, the chaperones can proofread three-dimensional protein structures and thus control protein quality in the cell. Understanding the mechanisms of the cellular unfoldases is central to the design of new therapies against aging, degenerative protein conformational diseases, and specific cancers. [ABSTRACT FROM AUTHOR]

Small Heat shock proteins (sHsps) are a family of molecular chaperones that bind nonnative proteins in an ATP-independent manner. Caenorhabditis elegans encodes 16 different sHsps, among them Hsp17, which is evolutionarily distinct from other sHsps in the nematode. The structure and mechanism of Hsp17 and how these may differ from other sHsps remain unclear. Here, we find that Hsp17 has a distinct expression pattern, structural organization, and chaperone function. Consistent with its presence under nonstress conditions, and in contrast to many other sHsps, we determined that Hsp17 is a mono-disperse, permanently active chaperone in vitro, which interacts with hundreds of different C. elegans proteins under physiological conditions. Additionally, our cryo-EM structure of Hsp17 reveals that in the 24-mer complex, 12 N-terminal regions are involved in its chaperone function. These flexible regions are located on the outside of the spherical oligomer, whereas the other 12 N-terminal regions are engaged in stabilizing interactions in its interior. This allows the same region in Hsp17 to perform different functions depending on the topological context. Taken together, our results reveal structural and functional features that further define the structural basis of permanently active sHsps., Competing Interests: Conflict of interest The authors declare that there is no conflict of interest., (Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved.)

Small heat shock proteins (sHSPs) comprise the most numerous, structurally diverse, and functionally uncharacterized family of heat shock proteins. Several Hsp genes ( Hsp 90 , 70 , 40 , and 27 ) from the insect Chironomus riparius are widely used in aquatic toxicology as biomarkers for environmental toxins. Here, we conducted a comparative study and characterized secondary structure of the six newly identified sHsp genes Hsp17 , Hsp21 , Hsp22 , Hsp23 , Hsp24 , and Hsp34 . A characteristic α-crystallin domain is predicted in all the new proteins. Phylogenetic analysis suggests a strong relation to other sHSPs from insects and interesting evidence regarding evolutionary origin and duplication events. Comparative analysis of transcription profiles for Hsp27 , Hsp70 , and the six newly identified genes revealed that Hsp17 , Hsp21 , and Hsp22 are constitutively expressed under normal conditions, while under two different heat shock conditions these genes are either not activated or are even repressed ( Hsp22 ). In contrast, Hsp23 , Hsp24 , and Hsp34 are significantly activated along with Hsp27 and Hsp70 during heat stress. These results strongly suggest functional differentiation within the small HSP subfamily and provide new data to help understand the coping mechanisms induced by stressful environmental stimuli. [ABSTRACT FROM AUTHOR]

A great number of studies have proven that sHsps protect cells by inhibiting protein aggregation under heat stress, while little is known about their function to protect cells under acid stress. In this work, we show that Hsp20.1 and Hsp14.1 oligomers dissociated to smaller oligomeric species or even dimer/monomer at low pH (pH 4.0 and pH 2.0), whereas no prominent quaternary structural changes were seen at 50 °C. Both oligomers and smaller oligomeric species exhibited abilities to suppress client aggregation at low pH and at 50 °C. These results suggest that sHsps may function in different modes in different stressed conditions. [ABSTRACT FROM AUTHOR]

Historically, small heat shock proteins (sHSPs) have been extensively studied in the context of being intracellular molecular chaperones. However, recent studies looking at the role of sHSPs in neurological diseases have demonstrated a near universal upregulation of certain sHSPs in damaged and diseased brains. Initially, it was thought that sHSPs are pathological in these disease states because they are found in the areas of damage. However, transgenic overexpression and exogenous administration of sHSPs in various experimental disease paradigms have shown just the contrary – that sHSPs are protective, not pathological. This review examines small heat shock proteins in neurological diseases and highlight the potential of using these neuroprotective sHSPs as novel therapeutics. It will first address the endogenous expression of sHSPs in a variety of neurological disorders. Secondly, it will focus on recent studies that have investigated the therapeutic potential of small heat shock proteins. Finally, it will provide a model of what we think is the function of small heat shock proteins in neurological diseases.