Family Of Molecular Chaperones Research Articles

Cloning and functional verification of the CmHSP17.9 gene from chrysanthemum.

Small molecular heat shock proteins (sHSPs) belong to the HSP family of molecular chaperones. Under high-temperature stress, they can prevent the aggregation of irreversible proteins and maintain the folding of denatured proteins to enhance heat resistance. In this study, the CmHSP17.9-1 and CmHSP17.9-2 genes, which were cloned from chrysanthemum (Chrysanthemum×morifolium 'Jinba') by homologous cloning, had a complete open reading frame of 480 bp each, encoding 159 amino acids. The protein subcellular localization analysis showed that CmHSP17.9-1 and CmHSP17.9-2 were located in the cytoplasm and mostly aggregated in granules, especially around the nucleus. Real-time quantitative PCR (qRT-PCR) analysis showed that the relative expression level of the CmHSP17.9-1 and CmHSP17.9-2 genes was highest in the terminal buds of the chrysanthemum, followed by the leaves. CmHSP17.9-1 and CmHSP17.9-2 overex-pression vectors were constructed and used to transform the chrysanthemum; overexpression of these genes led to the chrysanthemum phenotypes being less affected by high-temperature, and the antioxidant capacity was enhanced. The results showed that chrysanthemum with overex-pression of the CmHSP17.9-1 and CmHSP17.9-2 genes had stronger tolerance than the wild type chrysanthemum after high-temperature treatment or some degree of heat exercise, and overex-pression of the CmHSP17.9-1 gene led to stronger heat resistance than that of the CmHSP17.9-2 gene, providing an important theoretical basis for the subsequent molecular breeding and pro-duction applications of chrysanthemum.

Modulation of Heat Shock Protein Expression in Alveolar Adenocarcinoma Cells through Gold Nanoparticles and Cisplatin Treatment.

Heat-shock proteins (HSPs) are stress-responsive molecules belonging to the family of evolutionary molecular chaperones known to be crucial in many cancer types, including human alveolar adenocarcinoma cells (A549). These proteins are highly overexpressed in cancers to support their ability to accommodate imbalances in cell signalling, DNA alterations, proteins, and energy metabolism associated with oncogenesis. The current study evaluated the effects of gold nanoparticles (AuNPs) combined with cisplatin (CDDP) on molecular chaperone HSPs in A549 cells. It was found that AuNPs:CDDP decreased the percentage of cell viability (38.5%) measured using the modified lactated dehydrogenase (mLDH) and 3-[4,5-dimethylthiazole-2-yl]-2,5-diphenyltetrazolium bromide (MTT) assays. AuNPs:CDDP exposure caused a significant (p < 0.05) increase in reactive oxygen species (ROS) generation by 1.81-fold, apoptosis induction, and a decrease in the mitochondrial membrane potential (MMP) compared to AuNPs or CDDP alone. Similarly, exposure to the AuNPs:CDDP combination had pronounced cytotoxic effects on the expression of HSPs and PI3K/AKT/mTOR, as well as apoptosis-related proteins. The results demonstrate that the combination of AuNPs with CDDP might enhance the anticancer efficacy of CDDP.

Uloga glikoproteina 96 u karcinomu dojke

Glycoprotein 96 (gp96) is a member of the heat shock protein 90 family, which is an ubiquitous family of molecular chaperones that are involved in the regulation of protein folding and other essential cellular activities. Residing in the lumen of the endoplasmic reticulum, gp96 plays a key role in maintaining protein homeostasis, from assemblage to degradation. However, exposure to stressful conditions that disturb cellular homeostasis may translocate gp96 to the cell surface, which implies its additional functions, such as the regulation of intracellular signalling, proliferation, and apoptosis, as well as the modulation of the immune response. Besides its roles under physiological conditions, gp96 is also included in different stages of oncogenesis. In this review, we summarised available data on the structure, physiological, and pathophysiological roles of gp96, particularly in breast cancer oncogenesis.

Tissue distribution of cysteine string protein/DNAJC5 in C. elegans analysed by CRISPR/Cas9-mediated tagging of endogenous DNJ-14.

Cysteine string protein (CSP) is a member of the DnaJ/Hsp40 family of molecular chaperones. CSP is enriched in neurons, where it mainly localises to synaptic vesicles. Mutations in CSP-encoding genes in flies, worms, mice and humans result in neuronal dysfunction, neurodegeneration and reduced lifespan. Most attention has therefore focused on CSP's neuronal functions, although CSP is also expressed in non-neuronal cells. Here, we used genome editing to fluorescently tag the Caenorhabditis elegans CSP orthologue, dnj-14, to identify which tissues preferentially express CSP and hence may contribute to the observed mutant phenotypes. Replacement of dnj-14 with wrmScarlet caused a strong chemotaxis defect, as seen with other dnj-14 null mutants. In contrast, inserting the reporter in-frame to create a DNJ-14-wrmScarlet fusion protein had no effect on chemotaxis, indicating that C-terminal tagging does not impair DNJ-14 function. WrmScarlet fluorescence appeared most obvious in the intestine, head/pharynx, spermathecae and vulva/uterus in the reporter strains, suggesting that DNJ-14 is preferentially expressed in these tissues. Crossing the DNJ-14-wrmScarlet strain with GFP marker strains confirmed the intestinal and pharyngeal expression, but only a partial overlap with neuronal GFP was observed. DNJ-14-wrmScarlet fluorescence in the intestine was increased in response to starvation, which may be relevant to mammalian CSPα's role in microautophagy. DNJ-14's enrichment in worm reproductive tissues (spermathecae and vulva/uterus) parallels the testis-specific expression of CSPβ and CSPγ isoforms in mammals. Furthermore, CSPα messenger RNA is highly expressed in the human proximal digestive tract, suggesting that CSP may have a conserved, but overlooked, function within the gastrointestinal system.

HspB5 Chaperone Structure and Activity Are Modulated by Chemical-Scale Interactions in the ACD Dimer Interface.

Small heat shock proteins (sHsps) are a family of ATP-independent molecular chaperones that function as "holdases" and prevent protein aggregation due to changes in temperature, pH, or oxidation state. sHsps have a conserved α-crystallin domain (ACD), which forms the dimer building block, flanked by variable N- and C-terminal regions. sHsps populate various oligomeric states as a function of their sequestrase activity, and these dynamic structural features allow the proteins to interact with a plethora of cellular substrates. However, the molecular mechanisms of their dynamic conformational assembly and the interactions with various substrates remains unclear. Therefore, it is important to gain insight into the underlying physicochemical properties that influence sHsp structure in an effort to understand their mechanism(s) of action. We evaluated several disease-relevant mutations, D109A, F113Y, R116C, R120G, and R120C, in the ACD of HspB5 for changes to in vitro chaperone activity relative to that of wildtype. Structural characteristics were also evaluated by ANS fluorescence and CD spectroscopy. Our results indicated that mutation Y113F is an efficient holdase, while D109A and R120G, which are found in patients with myofibrillar myopathy and cataracts, respectively, exhibit a large reduction in holdase activity in a chaperone-like light-scattering assay, which indicated alterations in substrate-sHsp interactions. The extent of the reductions in chaperone activities are different among the mutants and specific to the substrate protein, suggesting that while sHsps are able to interact with many substrates, specific interactions provide selectivity for some substrates compared to others. This work is consistent with a model for chaperone activity where key electrostatic interactions in the sHsp dimer provide structural stability and influence both higher-order sHsp interactions and facilitate interactions with substrate proteins that define chaperone holdase activity.

The effect of HSP70 overexpression on the cerebral cortex development

Heat shock proteins (HSPs) make up a large family of molecular chaperones, recognized for their role in protein maturation, refolding, and degradation. HSP70 was shown to promote cell survival during several pathological processes in the brain, such as stroke, neurodegenerative diseases, epilepsy, and trauma [1]. In addition, HSPs serve to promote the proper embryonic and postnatal development of many organ systems, such as the central nervous system [2]. Heat shock proteins demonstrate specific expression patterns throughout the development of the nervous system, notably during crucial embryonic and postnatal moments [1]. During embryonic development, neural and glial progenitors must survive within a hypoxic microenvironment while performing energetically demanding actions, such as cell migration and neurite outgrowth. HSPs can activate or inhibit development pathways in the nervous system that modulate cell differentiation, neurite outgrowth, cell migration, or angiogenesis [1]. Indeed, recent studies demonstrated that HSP70 directly regulates the development of the nervous system by modulating signaling cascades involved in cell growth and migration [3]. Additionally, research demonstrated [4] that introducing HSP70 from an external source significantly augments the populations of proliferating cells and differentiated neuroblasts within the mouse hippocampus. Nevertheless, some researchers [1] contend that overexpression of HSPs may negatively impact cell survival. Therefore, the precise role of these chaperones remains largely unexplored. In our study, we used in utero electroporation to introduce plasmids that controlled HSP70 overexpression into neuron progenitors of mouse embryos on the 14th day of gestation. Additionally, plasmid DNA encoding GFP was used to facilitate subsequent visualization of transformed cells. Brain samples were collected on the 18th day of gestation for immunohistochemical analysis of the sections. Confocal microscopy was used to compare the characteristics of neuronal migration in both control and HSP70 overexpression conditions. Cells that received plasmids inducing HSP70 were discovered to migrate at a lower pace in comparison to the control. Additionally, it is hypothesized that the induction of HSP70 expression could lead to neuronal malformations and impact the development of neurites. In the future, the study of cytoarchitectonics in the cortex will continue, examining the identification of electroporated cells in individual neuron populations using Satb2 and Ctip2 markers. Additionally, the differentiation of these cells will be assessed by counting those that have not exited the mitotic cycle, and the hypothesis of apoptosis induction in cells electroporated with HSP70 will be tested.

Drought-responsive genes in tomato: meta-analysis of gene expression using machine learning

Plants have diverse molecular mechanisms to protect themselves from biotic and abiotic stressors and adapt to changing environments. To uncover the genetic potential of plants, it is crucial to understand how they adapt to adverse conditions by analyzing their genomic data. We analyzed RNA-Seq data from different tomato genotypes, tissue types, and drought durations. We used a time series scale to identify early and late drought-responsive gene modules and applied a machine learning method to identify the best responsive genes to drought. We demonstrated six candidate genes of tomato viz. Fasciclin-like arabinogalactan protein 2 (FLA2), Amino acid transporter family protein (ASCT), Arginine decarboxylase 1 (ADC1), Protein NRT1/PTR family 7.3 (NPF7.3), BAG family molecular chaperone regulator 5 (BAG5) and Dicer-like 2b (DCL2b) were responsive to drought. We constructed gene association networks to identify their potential interactors and found them drought-responsive. The identified candidate genes can help to explore the adaptation of tomato plants to drought. Furthermore, these candidate genes can have far-reaching implications for molecular breeding and genome editing in tomatoes, providing insights into the molecular mechanisms that underlie drought adaptation. This research underscores the importance of the genetic basis of plant adaptation, particularly in changing climates and growing populations.

Structural characterization of the human DjC20/HscB cochaperone in solution

J-domain proteins (JDPs) form a very large molecular chaperone family involved in proteostasis processes, such as protein folding, trafficking through membranes and degradation/disaggregation. JDPs are Hsp70 co-chaperones capable of stimulating ATPase activity as well as selecting and presenting client proteins to Hsp70. In mitochondria, human DjC20/HscB (a type III JDP that possesses only the conserved J-domain in some region of the protein) is involved in [FeS] protein biogenesis and assists human mitochondrial Hsp70 (HSPA9). Human DjC20 possesses a zinc-finger domain in its N-terminus, which closely contacts the J-domain and appears to be essential for its function. Here, we investigated the hDjC20 structure in solution as well as the importance of Zn+2 for its stability. The recombinant hDjC20 was pure, folded and capable of stimulating HSPA9 ATPase activity. It behaved as a slightly elongated monomer, as attested by small-angle X-ray scattering and SEC-MALS. The presence of Zn2+ in the hDjC20 samples was verified, a stoichiometry of 1:1 was observed, and its removal by high concentrations of EDTA and DTPA was unfeasible. However, thermal and chemical denaturation in the presence of EDTA led to a reduction in protein stability, suggesting a synergistic action between the chelating agent and denaturators that facilitate protein unfolding depending on metal removal. These data suggest that the affinity of Zn+2 for the protein is very high, evidencing its importance for the hDjC20 structure.

Deubiquitinase USP19 modulates apoptotic calcium release and endoplasmic reticulum stress by deubiquitinating BAG6 in triple negative breast cancer.

Triple-negative breast cancer (TNBC), a heterogeneous subtype of breast cancer (BC), had poor prognosis. Endoplasmic reticulum (ER) stress was responsible for cellular processes and played a crucial role in the cell function. ER stress is a complex and dynamic process that can induce abnormal apoptosis and death. However, the underlying mechanism of ER stress involved in TNBC is not well defined. We identified ubiquitin-specific protease 19 (USP19) as a TNBC negative regulator for further investigation. The effects of USP19 on BC proliferation were assessed in vitro using proliferation test and cell-cycle assays, while the effects in vivo were examined using a mouse tumorigenicity model. Through in vitro flow cytometric analyses and in vivo TUNEL assays, cell apoptosis was assessed. Proteomics was used to examine the proteins that interact with USP19. Multiple in vitro and in vivo tests showed that USP19 decreases TNBC cell growth while increasing apoptosis. Then, we demonstrated that USP19 interacts with deubiquitinates and subsequently stabilises family molecular chaperone regulator 6 (BAG6). BAG6 can boost B-cell lymphoma 2 (BCL2) ubiquitination and degradation, thereby raising ER calcium (Ca2+ ) levels and causing ER stress. We also found that the N6 -methyladenosine (m6 A) "writer" methyltransferase-like 14 (METTL14) increased global m6 A modification. Our study reveals that USP19 elevates the intracellular Ca2+ concentration to alter ER stress via regulation of BAG6 and BCL2 stability and may be a viable therapeutic target for TNBC therapy.

Synthesis and Validation of the First Cell-Impermeable Hsp90α-Selective Inhibitors.

Hsp90α is an isoform of the heat shock protein 90 (Hsp90) family of molecular chaperones and mediates the folding and activation of ∼400 client proteins. However, inhibition of intracellular Hsp90α has caused detrimental side effects and significantly hindered the clinical development of Hsp90 inhibitors. As an alternative strategy, 14 Hsp90α-selective inhibitors were synthesized to introduce permanently charged moieties onto the solvent-exposed portion of the Hsp90α binding site to produce cell-impermeable extracellular Hsp90α-selective inhibitors. The resulting lead compounds were cell-permeable dimethylamine 14 (NDNA3), with an affinity of 0.51 μM for Hsp90α and >196-fold selectivity over the other Hsp90 isoforms, and cell-impermeable quaternary ammonium 17 (NDNA4), with an affinity of 0.34 μM for Hsp90α and >294-fold selectivity. The permanently charged analogs were determined to have low membrane permeability, to be nontoxic against Ovcar-8 and MCF-10A cells, to avoid disruption of hERG channel maturation, and not to induce the heat shock response or Hsp90α-dependent client degradation.

Identification of gene networks mediating regional resistance to tauopathy in late-onset Alzheimer's disease.

Neurofibrillary lesions composed of tau protein aggregates are defining hallmarks of Alzheimer's Disease. Despite tau filaments appearing to spread between networked brain regions in a prion-like manner, certain areas including cerebellum resist trans-synaptic spread of tauopathy and degeneration of their constituent neuronal cell bodies. To identify molecular correlates of resistance, we derived and implemented a ratio of ratios approach for disaggregating gene expression data on the basis of regional vulnerability to tauopathic neurodegeneration. When applied to vulnerable pre-frontal cortex as an internal reference for resistant cerebellum, the approach segregated adaptive changes in expression into two components. The first was enriched for neuron-derived transcripts associated with proteostasis including specific members of the molecular chaperone family and was unique to resistant cerebellum. When produced as purified proteins, each of the identified chaperones depressed aggregation of 2N4R tau in vitro at sub-stoichiometric concentrations, consistent with the expression polarity deduced from ratio of ratios testing. In contrast, the second component enriched for glia- and microglia-derived transcripts associated with neuroinflammation, segregating these pathways from susceptibility to tauopathy. These data support the utility of ratio of ratios testing for establishing the polarity of gene expression changes with respect to selective vulnerability. The approach has the potential to identify new targets for drug discovery predicated on their ability to promote resistance to disease in vulnerable neuron populations.

Disordered region encodes α-crystallin chaperone activity toward lens client γD-crystallin

Small heat-shock proteins (sHSPs) are a widely expressed family of ATP-independent molecular chaperones that are among the first responders to cellular stress. Mechanisms by which sHSPs delay aggregation of client proteins remain undefined. sHSPs have high intrinsic disorder content of up to ~60% and assemble into large, polydisperse homo- and hetero-oligomers, making them challenging structural and biochemical targets. Two sHSPs, HSPB4 and HSPB5, are present at millimolar concentrations in eye lens, where they are responsible for maintaining lens transparency over the lifetime of an organism. Together, HSPB4 and HSPB5 compose the hetero-oligomeric chaperone known as α-crystallin. To identify the determinants of sHSP function, we compared the effectiveness of HSPB4 and HSPB5 homo-oligomers and HSPB4/HSPB5 hetero-oligomers in delaying the aggregation of the lens protein γD-crystallin. In chimeric versions of HSPB4 and HSPB5, chaperone activity tracked with the identity of the 60-residue disordered N-terminal regions (NTR). A short 10-residue stretch in the middle of the NTR ("Critical sequence") contains three residues that are responsible for high HSPB5 chaperone activity toward γD-crystallin. These residues affect structure and dynamics throughout the NTR. Abundant interactions involving the NTR Critical sequence reveal it to be a hub for a network of interactions within oligomers. We propose a model whereby the NTR critical sequence influences local structure and NTR dynamics that modulate accessibility of the NTR, which in turn modulates chaperone activity.

Role of Hsp70 in Post-Translational Protein Targeting: Tail-Anchored Membrane Proteins and Beyond.

The Hsp70 family of molecular chaperones acts as a central 'hub' in the cell that interacts with numerous newly synthesized proteins to assist in their biogenesis. Apart from its central and well-established role in facilitating protein folding, Hsp70s also act as key decision points in the cellular chaperone network that direct client proteins to distinct biogenesis and quality control pathways. In this paper, we review accumulating data that illustrate a new branch in the Hsp70 network: the post-translational targeting of nascent membrane and organellar proteins to diverse cellular organelles. Work in multiple pathways suggests that Hsp70, via its ability to interact with components of protein targeting and translocation machineries, can initiate elaborate substrate relays in a sophisticated cascade of chaperones, cochaperones, and receptor proteins, and thus provide a mechanism to safeguard and deliver nascent membrane proteins to the correct cellular membrane. We discuss the mechanistic principles gleaned from better-studied Hsp70-dependent targeting pathways and outline the observations and outstanding questions in less well-studied systems.

The permanently chaperone-active small heat shock protein Hsp17 from Caenorhabditis elegans exhibits topological separation of its N-terminal regions

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 invitro, 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.

Structure-Activity Relationship Study of Tertiary Alcohol Hsp90α-Selective Inhibitors with Novel Binding Mode.

The heat shock protein 90 (Hsp90) family of molecular chaperones mediates the folding and activation of client proteins associated with all 10 hallmarks of cancer. Herein, the design, synthesis, and biological validation of Hsp90α-selective inhibitors that contain a tertiary alcohol are reported. Forty-one analogues were synthesized to modulate hydrogen-bonding interactions and to probe for steric and hydrophobic interactions within the Hsp90α binding site. Cocrystal structures of lead compound 23d (IC50 = 0.25 μM, 15-fold selective vs Hsp90β) and a 5-fluoroisoindoline derivative (KUNA-111) revealed a novel binding mode that induced conformational changes within Hsp90α's N-terminal domain. The lead Hsp90α-selective inhibitors did not manifest significant antiproliferative activity, but they did result in selective and dose-dependent degradation of Hsp90α clients in the cellular environment. Additional studies will be sought to determine the effects of the novel conformational change induced by 23d.

Proteomic and phosphoproteomic profiling in heart failure with preserved ejection fraction (HFpEF)

Abstract Background The lack of therapies for HFpEF patients is a major unmet need, thus identifying cardiac specific pathways in HFpEF is a priority. Purpose Identify molecular features of protein and phosphoprotein in a murine model of HFpEF Methods Studies followed the principles of laboratory animal care (NIH Pub no. 85–23 revised 1985). HFpEF (N=4) was induced by NaCl drinking water, unilateral nephrectomy, and chronic aldosterone infusion (SAUNA) or saline (Sham; N=4) for 4 wks. Mice were euthanized and LV tissue was collected. Samples were homogenized, proteins extracted and subjected to digestion followed by phosphopeptide enrichment for proteomics and phosphoproteomics profiling. Results HFpEF mice had moderate hypertension (137.8±7.0 vs. Sham; 115.4±6.0mmHg; P&amp;lt;0.05), lung congestion (4.5±0.1 vs. 4.0±0.1; P&amp;lt;0.01), and LVH (3.7±0.1 vs. 3.3±0.1mg/g; P&amp;lt;0.05). ECHO showed normal LVEF with evidence of diastolic dysfunction in HFpEF mice. Mitral E velocity was reduced (1347±154 vs. 1971±284mm/s; P&amp;lt;0.05) and IVRT increased (24.3±2.6 vs. 14.4±1.6ms; P&amp;lt;0.05) vs. Sham. Protein and protein phosphosites from the LV were quantified by mass spectrometry. Analysis of the proteomics datasets revealed marked changes in sarcomere proteins, such as skeletal alpha (α)-actin (ACTA1; P=0.000039), beta (β)-myosin heavy chain (MYH7; P=0.006963) and myosin heavy chain 9 (MYH9; P=0.000408); the mitochondria-related proteins mitofusin 1 (MFN1; P=0.001059), mitochondrial dynamin like GTPase (aka optic atrophy protein 1, OPA1; P=0.046441) and transcription factor A mitochondrial (TFAM; P=0.005837); and the NAD-dependent protein deacetylase sirtuin-3 (SIRT3; P=0.000914). There was also a reduction in proteins involved in the oxidation of free fatty acid, pyruvate, and ketone bodies in the LV from HFpEF vs. Sham. Phosphoproteomics analysis also showed aberrant protein phosphorylation patterns linked to disparate subcellular compartments, ranging from sarcomere proteins (LIM domain-binding protein 3, LDB3; myozenin 2, Myoz2; titin, TTN), to nuclear-localized proteins (BAG family molecular chaperone regulator 3, BAG3; high mobility group protein HMG-I/HMG-Y, HMGA1) with known links to contractile dysfunction, LVH and/or cardiomyopathy. Additional GSEA analysis revealed the most relevant and enriched biological annotations in LV from HFpEF, to be processes involving immune system modulation and muscle contraction. Downregulated pathways were mainly related to multitude of GO terms associated with mitochondrial metabolism. Conclusion(s) This study presents the systematic, quantitative proteomics and phosphoproteomic analysis of the LV from the SAUNA HFpEF mice. We observed profound changes in proteins related to mitochondrial metabolism and function and heart contractile dysfunction in HFpEF which may be mediated by Sirtuin 3. Additional studies are warranted to investigate the specific role of Sirtuin 3 in mitochondrial metabolism and heart contractile dysfunction in HFpEF. Funding Acknowledgement Type of funding sources: Public grant(s) – EU funding. Main funding source(s): National Institute of Heath (NIH/ NHLBI)

Local Flexibility of a New Single-Ring Chaperonin Encoded by Bacteriophage AR9 Bacillus subtilis.

Chaperonins, a family of molecular chaperones, assist protein folding in all domains of life. They are classified into two groups: bacterial variants and those present in endosymbiotic organelles of eukaryotes belong to group I, while group II includes chaperonins from the cytosol of archaea and eukaryotes. Recently, chaperonins of a prospective new group were discovered in giant bacteriophages; however, structures have been determined for only two of them. Here, using cryo-EM, we resolved a structure of a new chaperonin encoded by gene 228 of phage AR9 B. subtilis. This structure has similarities and differences with members of both groups, as well as with other known phage chaperonins, which further proves their diversity.

The role of heat shock proteins in metastatic colorectal cancer: A review.

Heat shock proteins (HSPs) are a large molecular chaperone family classified by their molecular weights, including HSP27, HSP40, HSP60, HSP70, HSP90, and HSP110. HSPs are likely to have antiapoptotic properties and participate actively in various processes such as tumor cell proliferation, invasion, metastases, and death. In this review, we discuss comprehensively the functions of HSPs associated with the progression of colorectal cancer (CRC) and metastasis and resistance to cancer therapy. Taken together, HSPs have numerous clinical applications as biomarkers for cancer diagnosis and prognosis and potential therapeutic targets for CRC and its related metastases.

Regulation and physiological function of proteins for heat tolerance in cowpea (Vigna unguiculata) genotypes under controlled and field conditions.

The expression of heat shock proteins is considered a central adaptive mechanism to heat stress. This study investigated the expression of heat shock proteins (HSPs) and other stress-protective proteins against heat stress in cowpea genotypes under field (IT-96D-610 and IT-16) and controlled (IT-96D-610) conditions. Heat stress response analysis of proteins at 72 h in the controlled environment showed 270 differentially regulated proteins identified using label-free quantitative proteomics in IT-96D-610 plants. These plants expressed HSPs and chaperones [BAG family molecular chaperone 6 (BAG6), Multiprotein bridging factor1c (MBF1C) and cold shock domain protein 1 (CSDP1) in the controlled environment]. However, IT-96D-610 plants expressed a wider variety of small HSPs and more HSPs in the field. IT-96D-610 plants also responded to heat stress by exclusively expressing chaperones [DnaJ chaperones, universal stress protein and heat shock binding protein (HSBP)] and non-HSP proteins (Deg1, EGY3, ROS protective proteins, temperature-induced lipocalin and succinic dehydrogenase). Photosynthesis recovery and induction of proteins related to photosynthesis were better in IT-96D-610 because of the concurrent induction of heat stress response proteins for chaperone functions, protein degradation for repair and ROS scavenging proteins and PSII operating efficiency (Fq’/Fm′) than IT-16. This study contributes to identification of thermotolerance mechanisms in cowpea that can be useful in knowledge-based crop improvement.

The biology and inhibition of glucose-regulated protein 94/gp96.

The 94 kDa molecular chaperone, glucose-regulated protein 94 (Grp94), has garnered interest during the last decade due to its direct association with endoplasmic reticulum (ER) stress and disease. Grp94 belongs to the Hsp90 family of molecular chaperones and is a master regulator of ER homeostasis due to its ability to fold and stabilize proteins/receptors, and to chaperone misfolded proteins for degradation. Multiple studies have demonstrated that Grp94 knockdown or inhibition leads to the degradation of client protein substrates, which leads to disruption of disease-dependent signaling pathways. As a result, small molecule inhibitors of Grp94 have become a promising therapeutic approach to target a variety of disease states. Specifically, Grp94 has proven to be a promising target for cancer, glaucoma, immune-mediated inflammation, and viral infection. Moreover, Grp94-peptide complexes have been utilized effectively as adjuvants for vaccines against a variety of disease states. This work highlights the significance of Grp94 biology and the development of therapeutics that target this molecular chaperone in multiple disease states.