Specification of Hsp70 Function by Hsp40 Co-chaperones

Exploring efavirenz-DNA interactions: A multidisciplinary approach through electrochemical, toxicological, and in silico investigations

Recently, there has been a growing approach that approved drugs have been tested for additional purposes. Efavirenz is a non-nucleoside reverse transcriptase inhibitor used to treat human immunodeficiency virus infection. In addition, it has selective cytotoxic effects against cancer cells. This study constructed an electrochemical dsDNA nanobiosensor to monitor Efavirenz-dsDNA interaction based on the amine-functionalized multi-walled carbon nanotubes. The experimental conditions of the nanobiosensor, such as dropping the volume of nanomaterial suspension, activation of the nanosensor, and dsDNA concentration, were optimized. The peak currents of dsDNA bases were enhanced, and the peak potentials of Efavirenz have shifted to the less positive potential thanks to the modified sensor with amine-functionalized multi-walled carbon nanotubes. The interaction mechanism was also evaluated in incubated solutions. Docking calculations showed that Efavirenz is active in the large cleft regions of DNA that suggest minor groove binding. The effect of efavirenz on the expression profile of particular stress and possible DNA genotoxicity was studied via examining gene polymorphisms in hepatic cells. These findings align with previously released research that shows Efavirenz-treated hepatic cells to have altered mitochondrial function and elevated ROS levels.

Backbone NMR resonance assignment of Sis1, a type B J-domain protein from Saccharomyces cerevisiae

J-domain proteins (JDPs) are essential cochaperones of heat shock protein 70 (Hsp70), as they bind and deliver misfolded polypeptides while also stimulating ATPase activity, thereby mediating the refolding process and assisting Hsp70 in maintaining cellular proteostasis. Despite their importance, detailed structural information about JDP‒Hsp70 complexes is still being explored due to various technical challenges. One major challenge is the lack of more detailed structural data on full-length JDPs. Class A and B JDPs, the most extensively studied, are typically dimers of 300-400 residue polypeptides with central intrinsically disordered regions. These features complicate structural analysis via NMR and X-ray crystallography techniques. This work presents the 1H, 15N, and 13C backbone resonance assignments of the full-length (352 residues long) Sis1, a dimeric class B JDP from S. cerevisiae. Our study achieved 70.5% residue assignment distributed across the entire protein, providing probes in all Sis1 domains for the first time. To overcome this challenging task, strategies such as deuteration and 3D BEST-TROSY correlation experiments were used. The methods and results are detailed within the text. We are confident that this achievement will significantly benefit both the structural biology and the proteostasis scientific communities.

Structural-functional relevance of DNAJBs in protein aggregation and associated neurodegenerative diseases

DNAJ proteins, also known as HSP40s, are co-chaperones that regulate the multifunctionality of HSP70s in maintaining cellular protein homeostasis. The heterogeneous family of DNAJ co-chaperones is classified into three classes (A, B and C), where structural diversity within the class defines their specific functions. Among three classes, the DNAJB class of co-chaperones are associated with cellular compartment-specific protein folding, disaggregation and degradation of proteins and enables effective targeting of a broad spectrum of aggregation-prone substrate proteins. The structural divergence of DNAJBs is critical for regulating disaggregation and degradation functions through specific interactions with HSP70 and substrate proteins. While the role of DNAJBs in maintaining protein homeostasis is valuable in addressing protein aggregation in neurodegenerative diseases, a limited understanding of their mechanisms and cellular functions beyond co-chaperones restricts their therapeutic applications. In this review, the mechanism of DNAJBs regulating aggregation of pathogenic proteins such as α-synuclein, tau, amyloid-β, and huntingtin are discussed. Emphasis on the selectivity of DNAJBs towards folding, disaggregation and degradation functions of HSP70, substrate selection and involvement of different structural regions are explained to provide a structural and functional understanding of DNAJB proteins. Mutations in different DNAJBs linked with several proteins aggregation-related neuronal and neuromuscular diseases are discussed. The fundamental understanding of DNAJB diversity and functionality can assist future interventions for regulating protein homeostasis and managing associated diseases.

Single-nuclei transcriptome analysis of IgM+ cells isolated from channel catfish (Ictalurus punctatus) spleen

Catfish production is the primary aquaculture sector in the United States, and the key cultured species is channel catfish (Ictalurus punctatus). The major causes of production losses are pathogenic diseases, and the spleen, an important site of adaptive immunity, is implicated in these diseases. To examine the channel catfish immune system, single-nuclei transcriptomes of sorted and captured IgM+ cells were produced from adult channel catfish. Three channel catfish (~1 kg) were euthanized, the spleen dissected, and the tissue dissociated. The lymphocytes were isolated using a Ficoll gradient and IgM+ cells were then sorted with flow cytometry. The IgM+ cells were lysed and single-nuclei libraries generated using a Chromium Next GEM Single Cell 3' GEM Kit and the Chromium X Instrument (10x Genomics) and sequenced with the Illumina NovaSeq X Plus sequencer. The reads were aligned to the I. punctatus reference assembly (Coco_2.0) using Cell Ranger, and normalization, cluster analysis, and differential gene expression analysis were carried out with Seurat. Across the three samples, approximately 753.5 million reads were generated for 18,686 cells. After filtering, 10,637 cells remained for the cluster analysis. The cluster analysis identified 16 clusters which were classified as B cells (10,276), natural killer-like (NK-like) cells (178), T cells or natural killer cells (45), hematopoietic stem and progenitor cells (HSPC)/megakaryocytes (MK) (66), myeloid/epithelial cells (40), and plasma cells (32). The B cell clusters were further defined as different populations of mature B cells, cycling B cells, and plasma cells. The plasma cells highly expressed ighm and we demonstrated that the secreted form of the transcript was largely being expressed by these cells. This atlas provides insight into the gene expression of IgM+ immune cells in channel catfish. The atlas is publicly available and could be used garner more important information regarding the gene expression of splenic immune cells.

DNAJB2 Attenuates Rosacea Skin Inflammation and Angiogenesis by Inhibiting the Endoplasmic Reticulum Stress-mediated TLR2/Myd88/NF-κB pathway

Endoplasmic reticulum stress (ERS) has recently been proposed as a core factor in the pathogenesis and aggravation of rosacea. The roles of ERS-related genes in rosacea are largely unknown and were investigated in this study. Rosacea microarray datasets were downloaded from the Gene Expression Omnibus (GEO) database. Differentially expressed ERS-related genes in rosacea patients vs. controls were screened using the Limma package, and LASSO regression was used to screen for characteristic genes. The infiltrating fraction was evaluated using ssGSEA. Clinical rosacea samples, age-matched healthy volunteers, and LL37-induced mice models were used to investigate the expression of DNAJB2 and its function. In the GSE65914 dataset, 17 differentially expressed ERS-related genes were screened. Of these, 13 were identified as characteristic genes predicting rosacea risk. The adaptive immune response, TLR signaling pathway, and chemokine signaling pathway were activated with a high risk of rosacea. After expression validation using the GSE155141 dataset, DNAJB2 was identified as a key gene. DNAJB2 expression was significantly decreased in both datasets, clinical samples, and the LL37-induced mice model. DNAJB2 overexpression could alleviate rosacea skin injury and inhibit expression of inflammatory cytokines and chemokines as well as angiogenesis. The infiltration levels of the majority of immune cell types were elevated in rosacea samples, and DNAJB2 overexpression inhibited CD4 + T cell infiltration, as well as Th1 and Th17 polarizing genes. Moreover, DNAJB2 could inhibit ERS marker proteins and the activated TLR2/Myd88/NF-κB pathway. DNAJB2 may be a novel target for rosacea treatment.

ZmDnaJ-ZmNCED6 module positively regulates drought tolerance via modulating stomatal closure in maize

Heat Shock Protein plays a vital role in maintaining protein homeostasis and protecting cells from stress stimulation. As one of the HSP40 proteins, DnaJ is a stress response protein widely existing in plant cells. The function and regulatory mechanism of ZmDnaJ, a novel chloroplast-localized type-III HSP40, in maize drought tolerance were characterized. Tissue-specific expression analysis showed that ZmDnaJ is highly expressed in the leaves, and is strongly drought-induced in maize seedlings. Overexpression of ZmDnaJ improved maize drought tolerance by enhancing stomatal closure and increasing ABA content to mediate photosynthesis. In contrast, the CRISPR-Cas9 knockout zmdnaj mutant showed lower relative water content and high sensitivity to drought stress. Moreover, Y2H, BiFC and Co-IP analyses revealed that ZmDnaJ interacts with an ABA synthesis-related protein ZmNCED6 to regulate drought tolerance. Similarly, ZmNCED6 overexpressed lines showed stronger oxidation resistance, enhanced photosynthetic rate, stomatal closure and ABA content, whilst the CRISPR-Cas9 knockout mutant showed sensitive to drought stress. More importantly, ZmDnaJ could regulate key drought tolerance genes (ZmPYL10, ZmPP2C44, ZmEREB65, ZmNCED4, ZmNCED6 and ZmABI5), involved in ABA signal transduction pathways. Taken together, our findings suggest that ZmDnaJ-ZmNCED6 module improves drought tolerance in maize.

Heat shock protein 70 in Alzheimer's disease and other dementias: A possible alternative therapeutic

Alzheimer's disease (AD) is considered a global health issue with a high social burden due to the level of disability it causes in those who suffer from it. In the absence of a therapeutic alternative for this disease, we will follow one of the biochemical pathways involved in the development of AD, which is related to molecular chaperones. The molecules are responsible for eliminating toxins and misfolded proteins at the cerebral level. These chaperones are a set of proteins from the heat shock proteins (HSPs) family, which, among their functions, help maintain homeostasis and protect cells against stress. Various authors have described the activity of HSPs in different neurodegenerative diseases, highlighting the activity of heat shock protein 70 (HSP70) in the presence of aberrant proteins characteristic of neurodegeneration, such as amyloid-β (Aβ) and tau. The role of HSP70 in AD and other dementias lies in its mechanism, which, along with other proteins from the HSP family, has the capacity to eliminate Aβ aggregates by promoting catalytic pathways. In this review, we explore the biological role of the HSP70 protein in AD and other dementias and its potential therapeutic use.

GRAIL1 Stabilizes Misfolded Mutant p53 through a Ubiquitin Ligase-Independent, Chaperone Regulatory Function

Frequent (>70%) TP53 mutations often promote its protein stabilization, driving esophageal adenocarcinoma (EAC) development linked to poor survival and therapy resistance. We previously reported that during Barrett's esophagus progression to EAC, an isoform switch occurs in the E3 ubiquitin ligase RNF128 (aka GRAIL-gene related to anergy in lymphocytes), enriching isoform 1 (hereby GRAIL1) and stabilizing the mutant p53 protein. Consequently, GRAIL1 knockdown degrades mutant p53. But, how GRAIL1 stabilizes the mutant p53 protein remains unclear. In search for a mechanism, here, we performed biochemical and cell biology studies to identify that GRAIL has a binding domain (315-PMCKCDILKA-325) for heat shock protein 40/DNAJ. This interaction can influence DNAJ chaperone activity to modulate misfolded mutant p53 stability. As predicted, either the overexpression of a GRAIL fragment (Frag-J) encompassing the DNAJ binding domain or a cell-permeable peptide (Pep-J) encoding the above 10 amino acids can bind and inhibit DNAJ-Hsp70 co-chaperone activity, thus degrading misfolded mutant p53. Consequently, either Frag-J or Pep-J can reduce the survival of mutant p53 containing dysplastic Barrett's esophagus and EAC cells and inhibit the growth of patient-derived organoids of dysplastic Barrett's esophagus in 3D cultures. The misfolded mutant p53 targeting and growth inhibitory effects of Pep-J are comparable with simvastatin, a cholesterol-lowering drug that can degrade misfolded mutant p53 also via inhibiting DNAJA1, although by a distinct mechanism. Implications: We identified a novel ubiquitin ligase-independent, chaperone-regulating domain in GRAIL and further synthesized a first-in-class novel misfolded mutant p53 degrading peptide having future translational potential.

Genome-Wide Identification and Interaction Analysis of Turbot Heat Shock Protein 40 and 70 Families Suggest the Mechanism of Chaperone Proteins Involved in Immune Response after Bacterial Infection

Hsp40-Hsp70 typically function in concert as molecular chaperones, and their roles in post-infection immune responses are increasingly recognized. However, in the economically important fish species Scophthalmus maximus (turbot), there is still a lack in the systematic identification, interaction models, and binding site analysis of these proteins. Herein, 62 Hsp40 genes and 16 Hsp70 genes were identified in the turbot at a genome-wide level and were unevenly distributed on 22 chromosomes through chromosomal distribution analysis. Phylogenetic and syntenic analysis provided strong evidence in supporting the orthologies and paralogies of these HSPs. Protein-protein interaction and expression analysis was conducted to predict the expression profile after challenging with Aeromonas salmonicida. dnajb1b and hspa1a were found to have a co-expression trend under infection stresses. Molecular docking was performed using Auto-Dock Tool and PyMOL for this pair of chaperone proteins. It was discovered that in addition to the interaction sites in the J domain, the carboxyl-terminal domain of Hsp40 also plays a crucial role in its interaction with Hsp70. This is important for the mechanistic understanding of the Hsp40-Hsp70 chaperone system, providing a theoretical basis for turbot disease resistance breeding, and effective value for the prevention of certain diseases in turbot.

BAG5 regulates HSPA8-mediated protein folding required for sperm head-tail coupling apparatus assembly

Teratozoospermia is a significant cause of male infertility, but the pathogenic mechanism of acephalic spermatozoa syndrome (ASS), one of the most severe teratozoospermia, remains elusive. We previously reported Spermatogenesis Associated 6 (SPATA6) as the component of the sperm head-tail coupling apparatus (HTCA) required for normal assembly of the sperm head-tail conjunction, but the underlying molecular mechanism has not been explored. Here, we find that the co-chaperone protein BAG5, expressed in step 9-16 spermatids, is essential for sperm HTCA assembly. BAG5-deficient male mice show abnormal assembly of HTCA, leading to ASS and male infertility, phenocopying SPATA6-deficient mice. In vivo and in vitro experiments demonstrate that SPATA6, cargo transport-related myosin proteins (MYO5A and MYL6) and dynein proteins (DYNLT1, DCTN1, and DNAL1) are misfolded upon BAG5 depletion. Mechanistically, we find that BAG5 forms a complex with HSPA8 and promotes the folding of SPATA6 by enhancing HSPA8's affinity for substrate proteins. Collectively, our findings reveal a novel protein-regulated network in sperm formation in which BAG5 governs the assembly of the HTCA by activating the protein-folding function of HSPA8.

Hyperthermic shift and cell engineering increase small extracellular vesicle production in HEK293F cells

Although small extracellular vesicles (sEVs) have promising features as an emerging therapeutic format for a broad spectrum of applications, for example, blood-brain-barrier permeability, low immunogenicity, and targeted delivery, economic manufacturability will be a crucial factor for the therapeutic applicability of sEVs. In the past, bioprocess optimization and cell line engineering improved titers of classical biologics multifold. We therefore performed a design of experiments (DoE) screening to identify beneficial bioprocess conditions for sEV production in HEK293F suspension cells. Short-term hyperthermia at 40°C elevated volumetric productivity 5.4-fold while sEVs displayed improved exosomal characteristics and cells retained >90% viability. Investigating the effects of hyperthermia via transcriptomics and proteomics analyses, an expectable, cellular heat-shock response was found together with an upregulation of many exosome biogenesis and vesicle trafficking related molecules, which could cause the productivity boost in tandem with heat shock proteins (HSPs), like HSP90 and HSC70. Because of these findings, a selection of 44 genes associated with exosome biogenesis, vesicle secretion machinery, or heat-shock response was screened for their influence on sEV production. Overexpression of six genes, CHMP1A, CHMP3, CHMP5, VPS28, CD82, and EZR, significantly increased both sEV secretion and titer, making them suitable targets for cell line engineering.

J-domain proteins: From molecular mechanisms to diseases

J-domain proteins (JDPs) are the largest family of chaperones in most organisms, but much of how they function within the network of other chaperones and protein quality control machineries is still an enigma. Here, we report on the latest findings related to JDP functions presented at a dedicated JDP workshop in Gdansk, Poland. The report does not include all (details) of what was shared and discussed at the meeting, because some of these original data have not yet been accepted for publication elsewhere or represented still preliminary observations at the time.

Lobular distribution of enhanced expression levels of heat shock proteins using in-situ hybridization in the mouse liver treated with a single administration of CCl4

This study was conducted to visualize the lobular distribution of enhanced mRNA expression levels of heat shock proteins (HSPs) in liver samples from carbon tetra chloride (CCl4)-treated mice using in-situ hybridization (ISH). Male BALB/c mice given a single oral administration of CCl4 were euthanized 6 hours or 1 day after the administration (6 h or 1 day). Paraffin-embedded liver samples were obtained, ISH for HSPs was conducted, as well as hematoxylin-eosin staining and immunohistochemistry (IHC). At 6 h, centrilobular hepatocellular vacuolization was observed, and increased signals for Hspa1a, Hspa1b, and Grp78, which are HSPs, were noted in the centrilobular area using ISH. At 1 day, zonal hepatocellular necrosis was observed in the centrilobular area, but mRNA signal increases for HSPs were no longer observed there. Some discrepancies between ISH and IHC for HSPs were observed, and they might be partly caused by post-transcriptional gene regulation, including the ribosome quality control mechanisms. It is known that CCl4 damages centrilobular hepatocytes through metabolization by cytochrome P450, mainly located in the centrilobular region, and HSPs are induced under cellular stress. Therefore, our ISH results visualized increased mRNA expression levels of HSPs in the centrilobular hepatocytes of mice 6 hours after a single administration of CCl4 as a response to cellular stress, and it disappeared 1 day after the treatment when remarkable necrosis was observed there.

The Plasmodium falciparum exported J domain proteins fine-tune human and malarial Hsp70s: pathological exploitation of proteostasis machinery

Cellular proteostasis requires a network of molecular chaperones and co-chaperones, which facilitate the correct folding and assembly of other proteins, or the degradation of proteins misfolded beyond repair. The function of the major chaperones, heat shock protein 70 (Hsp70) and heat shock protein 90 (Hsp90), is regulated by a cohort of co-chaperone proteins. The J domain protein (JDP) family is one of the most diverse co-chaperone families, playing an important role in functionalizing the Hsp70 chaperone system to form a powerful protein quality control network. The intracellular malaria parasite, Plasmodium falciparum, has evolved the capacity to invade and reboot mature human erythrocytes, turning them into a vehicles of pathology. This process appears to involve the harnessing of both the human and parasite chaperone machineries. It is well known that malaria parasite-infected erythrocytes are highly enriched in functional human Hsp70 (HsHsp70) and Hsp90 (HsHsp90), while recent proteomics studies have provided evidence that human JDPs (HsJDPs) may also be enriched, but at lower levels. Interestingly, P. falciparum JDPs (PfJDPs) are the most prominent and diverse family of proteins exported into the infected erythrocyte cytosol. We hypothesize that the exported PfJPDs may be an evolutionary consequence of the need to boost chaperone power for specific protein folding pathways that enable both survival and pathogenesis of the malaria parasite. The evidence suggests that there is an intricate network of PfJDP interactions with the exported malarial Hsp70 (PfHsp70-x) and HsHsp70, which appear to be important for the trafficking of key malarial virulence factors, and the proteostasis of protein complexes of human and parasite proteins associated with pathology. This review will critically evaluate the current understanding of the role of exported PfJDPs in pathological exploitation of the proteostasis machinery by fine-tuning the chaperone properties of both human and malarial Hsp70s.

Decreased Levels of Chaperones in Mucopolysaccharidoses and Their Elevation as a Putative Auxiliary Therapeutic Approach

Mucopolysaccharidoses (MPS) are rare genetic disorders belonging to the lysosomal storage diseases. They are caused by mutations in genes encoding lysosomal enzymes responsible for degrading glycosaminoglycans (GAGs). As a result, GAGs accumulate in lysosomes, leading to impairment of cells, organs and, consequently, the entire body. Many of the therapies proposed thus far require the participation of chaperone proteins, regardless of whether they are therapies in common use (enzyme replacement therapy) or remain in the experimental phase (gene therapy, STOP-codon-readthrough therapy). Chaperones, which include heat shock proteins, are responsible for the correct folding of other proteins to the most energetically favorable conformation. Without their appropriate levels and activities, the correct folding of the lysosomal enzyme, whether supplied from outside or synthesized in the cell, would be impossible. However, the baseline level of nonspecific chaperone proteins in MPS has never been studied. Therefore, the purpose of this work was to determine the basal levels of nonspecific chaperone proteins of the Hsp family in MPS cells and to study the effect of normalizing GAG concentrations on these levels. Results of experiments with fibroblasts taken from patients with MPS types I, II, IIIA, IIIB, IIIC, IID, IVA, IVB, VI, VII, and IX, as well as from the brains of MPS I mice (Idua^-/-), indicated significantly reduced levels of the two chaperones, Hsp70 and Hsp40. Interestingly, the reduction in GAG levels in the aforementioned cells did not lead to normalization of the levels of these chaperones but caused only a slight increase in the levels of Hsp40. An additional transcriptomic analysis of MPS cells indicated that the expression of other genes involved in protein folding processes and the cell response to endoplasmic reticulum stress, resulting from the appearance of abnormally folded proteins, was also modulated. To summarize, reduced levels of chaperones may be an additional cause of the low activity or inactivity of lysosomal enzymes in MPS. Moreover, this may point to causes of treatment failure where the correct structure of the enzyme supplied or synthesized in the cell is crucial to lower GAG levels.