Hsp90: structure and function

Hsp90α promotes lipogenesis by stabilizing FASN and promoting FASN transcription via LXRα in hepatocellular carcinoma

Excessive lipid accumulation promotes the occurrence and progression of hepatocellular carcinoma (HCC), accompanied by high levels of fatty acid synthetase (FASN) and more active lipogenesis. Heat shock protein 90 (Hsp90) acts as a chaperone to maintain the stability and activity of the client proteins. Studies have revealed that Hsp90 regulates the lipid metabolism of HCC, but the effect of Hsp90 on FASN still remains unknown. This study aims to discover the mechanism of Hsp90 inhibition on lipid accumulation and investigate the different effects of Hsp90 N-terminal domain inhibitor STA9090 and C-terminal domain inhibitor novobiocin (NB) on FASN protein stability and transcription pathway in HCC. We found that HCC cells tended to store lipids, which could be disrupted by Hsp90 inhibitors in vivo and in vitro. High levels of Hsp90α and FASN in tumor tissue had correlation with poor prognosis of HCC patients and Hsp90α interacted with FASN to maintain its protein stability. Furthermore, N-terminal domain of Hsp90α was essential for process of sterol regulatory element binding protein 1 (SREBP1) to activate FASN transcription and Hsp90α prevented proteasomal degradation of liver X receptor α (LXRα) to upregulate FASN transcription via LXRα/SREBP1 axis. Our data reveals that Hsp90α promotes lipid accumulation by increasing the protein stability and FASN mRNA transcription, and can be alleviated by Hsp90 inhibitors, which provides a theoretical basis for Hsp90-targeted therapy on lipid metabolism in HCC.

Proteostasis is a key driver of the pathogenesis in Apicomplexa

Proteostasis, including protein folding mediated by molecular chaperones, protein degradation, and stress response pathways in organelles like ER (unfolded protein response: UPR), are responsible for cellular protein quality control. This is essential for cell survival as it regulates and reprograms cellular processes. Here, we underscore the role of the proteostasis pathway in Apicomplexan parasites with respect to their well-characterized roles as well as potential roles in many parasite functions, including survival, multiplication, persistence, and emerging drug resistance. In addition to the diverse physiological importance of proteostasis in Apicomplexa, we assess the potential of the pathway's components as chemotherapeutic targets.

Auto QSAR-based active learning docking for hit identification of potential inhibitors of Plasmodium falciparum Hsp90 as antimalarial agents

Malaria which is mainly caused by Plasmodium falciparum parasite remains a devastating public health concern, necessitating the need to develop new antimalarial agents. P. falciparum heat shock protein 90 (Hsp90), is indispensable for parasite survival and a promising drug target. Inhibitors targeting the ATP-binding pocket of the N-terminal domain have anti-Plasmodium effects. We proposed a de novo active learning (AL) driven method in tandem with docking to predict inhibitors with unique scaffolds and preferential selectivity towards PfHsp90. Reference compounds, predicted to bind PfHsp90 at the ATP-binding pocket and possessing anti-Plasmodium activities, were used to generate 10,000 unique derivatives and to build the Auto-quantitative structures activity relationships (QSAR) models. Glide docking was performed to predict the docking scores of the derivatives and > 15,000 compounds obtained from the ChEMBL database. Re-iterative training and testing of the models was performed until the optimum Kennel-based Partial Least Square (KPLS) regression model with a regression coefficient R2 = 0.75 for the training set and squared correlation prediction Q2 = 0.62 for the test set reached convergence. Rescoring using induced fit docking and molecular dynamics simulations enabled us to prioritize 15 ATP/ADP-like design ideas for purchase. The compounds exerted moderate activity towards P. falciparum NF54 strain with IC50 values of ≤ 6μM and displayed moderate to weak affinity towards PfHsp90 (KD range: 13.5-19.9μM) comparable to the reported affinity of ADP. The most potent compound was FTN-T5 (PfN54 IC50:1.44μM; HepG2/CHO cells SI≥ 29) which bound to PfHsp90 with moderate affinity (KD:7.7μM), providing a starting point for optimization efforts. Our work demonstrates the great utility of AL for the rapid identification of novel molecules for drug discovery (i.e., hit identification). The potency of FTN-T5 will be critical for designing species-selective inhibitors towards developing more efficient agents against malaria.

Design, synthesis and biological studies of new isoxazole compounds as potent Hsp90 inhibitors

Heat shock protein 90 (Hsp90), a molecular chaperone, contributes to the preservation of folding, structure, stability, and function proteins. In this study, novel compounds comprising isoxazole structure were designed, synthesized and their potential ability as Hsp90 inhibitors was validated through docking studies. The active site-based compounds were prepared through a multi-step synthesis process and their chemical structures were characterized employing FT-IR, NMR, and mass spectrometry analysis. Cytotoxic and Hsp90 inhibition activities of synthesized compounds were assessed by MTT assay and ELISA kit, respectively. Based on the obtained results, compound 5 exhibited the highest cytotoxicity (IC50; 14 µM) against cancer cells and reduced Hsp90 expression from 5.54 ng/mL in untreated (normal cells) to 1.56 ng/mL in cancer cells. Moreover, molecular dynamics (MD) simulation results indicated its high affinity to target protein and approved its excellent stability which is essential for exerting an inhibitory effect on cancer cell proliferation.

Small molecules for impairing endoplasmic reticulum in cancer

The endoplasmic reticulum plays an important role in maintaining the protein homeostasis of cells as well as regulating Ca2+ storage. An increased load of unfolded proteins in the endoplasmic reticulum due to alterations in the cell's metabolic pathway leads to the activation of the unfolded protein response, also known as ER stress. ER stress plays a major role in maintaining the growth and survival of various cancer cells, but persistent ER stress can also lead to cell death and hence can be a therapeutic pathway in the treatment of cancer. In this review, we focus on different types of small molecules that impair different ER stress sensors, the protein degradation machinery, and chaperone proteins. We also review the metal complexes and other miscellaneous compounds inducing ER stress through multiple mechanisms. Finally, we discuss the challenges in this emerging area of research and the potential direction of research to overcome them towards next-generation ER-targeted cancer therapy.

Targeting chaperone modifications: Innovative approaches to cancer treatment

Cancer and other chronic diseases are marked by alterations in the protein quality control system, affecting the posttranslational destiny of various proteins that regulate, structure, and catalyze cellular processes. Cellular chaperones, also known as heat shock proteins (HSPs), are pivotal in this system, performing protein triage that often determines the fate of proteins they bind to. Grasping the regulatory mechanisms of HSPs and their associated cofactors is crucial for understanding protein quality control in both healthy and diseased states. Recent research has shed light on the interactions within the protein quality control system and how post-translational modification govern protein interactions, function, and localization, which can drive or inhibit cell proliferation. This body of work encompasses critical elements of the heat shock response, including heat shock protein 70, heat shock protein 90, carboxyl-terminus of HSC70 interacting protein, and heat shock protein organizing protein. This review aims to synthesize these advancements, offering a holistic understanding of the system and its response when commandeered by diseases like cancer. We focus on the mechanistic shift in co-chaperone engagement-transitioning from heat shock protein organizing protein to carboxyl-terminus of HSC70 interacting protein in association with heat shock protein 70 and heat shock protein 90-which could influence cellular growth and survival pathways. A comprehensive examination of posttranslational modification-driven regulation within the protein quality control network is presented, highlighting the roles of activation factors, chaperones, and co-chaperones. Our insights aim to inform new strategies for therapeutically targeting diseases by considering the entire heat shock response system.

Effect of Benzyl Alcohol on Main Defense System Components of Galleria mellonella (Lepidoptera)

Benzyl alcohol (E1519) is an aromatic alcohol used in the pharmaceutical and food industry. It is used to protect food products against microorganisms during storage, as a flavoring in the production of chocolate and confectionery products, as an important ingredient in fragrance, and as a preservative in medical products. However, little is known of its effect on insects. The main aim of this study was to determine the influence of benzyl alcohol on the defense systems of the wax moth Galleria mellonella, i.e., its cuticular lipid composition and critical elements of its immune system. A gas chromatography/mass spectrometry (GC/MS) analysis found benzyl alcohol treatment to elicit significant quantitative and qualitative differences in cuticular free fatty acid (FFA) profiles. Our findings indicate that benzyl alcohol treatment increased the levels of HSP70 and HSP90 and decreased those of HSF1, histamine, and cysteinyl leukotriene. Benzyl alcohol application also increased dismutase level in the hemolymph and lowered those of catalase and 8-OHdG. The treatment also had negative effects on G. mellonella hemocytes and a Sf9 cell line in vitro: 48-h treatment resulted in morphological changes, with the remaining cells being clearly spindle-shaped with numerous granules. The high insecticidal activity of compound and its lack of toxicity towards vertebrates suggest it could be an effective insecticide.

Small molecule inhibitors targeting heat shock protein 90: An updated review

As a molecular chaperone, heat shock protein 90 (HSP90) plays important roles in the folding, stabilization, activation, and degradation of over 500 client proteins, and is extensively involved in cell signaling, proliferation, and survival. Thus, it has emerged as an important target in a variety of diseases, including cancer, neurodegenerative diseases, and viral infections. Therefore, targeted inhibition of HSP90 provides a valuable and promising therapeutic strategy for the treatment of HSP90-related diseases. This review aims to systematically summarize the progress of research on HSP90 inhibitors in the last five years, focusing on their structural features, design strategies, and biological activities. It will refer to the natural products and their derivatives (including novobiocin derivatives, deguelin derivatives, quinone derivatives, and terpenoid derivatives), and to synthetic small molecules (including resorcinol derivatives, pyrazoles derivatives, triazole derivatives, pyrimidine derivatives, benzamide derivatives, benzothiazole derivatives, and benzofuran derivatives). In addition, the major HSP90 small-molecule inhibitors that have moved into clinical trials to date are also presented here.

Selective nitration of Hsp90 acts as a metabolic switch promoting tumor cell proliferation

Tumors develop in an oxidative environment characterized by peroxynitrite production and downstream protein tyrosine (Y) nitration. We showed that tyrosine nitration supports schwannoma cell proliferation and regulates cell metabolism in the inheritable tumor disorder NF2-related Schwannomatosis (NF2-SWN). Here, we identified the chaperone Heat shock protein 90 (Hsp90) as the first nitrated protein that acts as a metabolic switch to promote schwannoma cell proliferation. Doubling the endogenous levels of nitrated Hsp90 in schwannoma cells or supplementing nitrated Hsp90 into normal Schwann cells increased their proliferation. Metabolically, nitration on either Y33 or Y56 conferred Hsp90 distinct functions; nitration at Y33 (Hsp90NY33) down-regulated mitochondrial oxidative phosphorylation, while nitration at Y56 (Hsp90NY56) increased glycolysis by activating the purinergic receptor P2X7 in both schwannoma and normal Schwann cells. Hsp90NY33 and Hsp90NY56 showed differential subcellular and spatial distribution corresponding with their metabolic and proliferative functions in schwannoma three-dimensional cell culture models. Collectively, these results underscore the role of tyrosine nitration as a post-translational modification regulating critical cellular processes. Nitrated proteins, particularly nitrated Hsp90, emerge as a novel category of tumor-directed therapeutic targets.

Dietary Tenebrio molitor larvae meal effects on cellular stress responses, antioxidant status and intermediate metabolism of Oncorhynchus mykiss

In the context of evaluating the impact of environmentally friendly and sustainably produced alternative protein sources in fish feed, the present study's aim was to examine the overall physiological stress response in one of the main fish species of European freshwater aquaculture, Oncorhynchus mykiss (rainbow trout), following the partial substitution of fish meal (FM) with a Tenebrio molitor (TM) (yellow mealworm) full-fat meal. In total, 222 rainbow trout individuals (115.2 ± 14.2 g) were allocated randomly into six tanks, three per dietary treatment, and were fed a formulated diet containing 60% yellow mealworm (TM60) compared to a control diet without insect meal (TM0). Both diets contained equal amounts of crude protein, dry matter and, lipid content, while the FM in TM60 was 100 g kg-1 corresponding to the one seventh of the TM0. Heat shock response (HSR), MAPK signalling, cell death pathways (apoptosis and autophagy), antioxidant defence mechanisms, and intermediate metabolism were evaluated. In general, HSR and MAPK signalling were activated in response to the inclusion of T. molitor. Moreover, triggering of apoptotic and autophagic processes and the onset of antioxidant defence mechanisms underlined the existence of physiological stress. Despite the apparent dietary-induced stress, rainbow trout in the present study exhibited no mortality and no significant effects regarding growth performance parameters. Specifically, TM60 dietary inclusion resulted in no changes in final body weight, weight gain, and specific growth rate. However, feed intake depicted a statistically significant decrease in TM60 fish compared to TM0 individuals. Nevertheless, nutrient stress should be considered a limiting factor regarding the utilization of T. molitor in O. mykiss diet due to the associated risks for health and welfare.

Mesenchymal stem cell-derived exosomes ameliorate hypoxic pulmonary hypertension by inhibiting the Hsp90aa1/ERK/pERK pathway

Hypoxic pulmonary hypertension (HPH) is a serious and life-threatening chronic cardiopulmonary disease characterized by progressive elevation of pulmonary artery pressure and pulmonary vascular remodeling. Mesenchymal stem cell- derived exosomes (MSC-Exos) can relieve HPH by reversing pulmonary vascular remodeling. The HPH model was established in healthy male Sprague-Dawley (SD) rats aged 6 to 8 weeks. The rats were placed in a room with oxygen concentration of (10 ± 1) % for 8 hours a day over 28 days, were then injected intravenously with MSC-Exos (100 ug protein/kg) or equal-volume phosphate buffer saline (PBS) once a day over 1 week. Right ventricular systolic pressure (RVSP), right ventricular hypertrophy index (RVHI) and pulmonary vascular remodeling were observed after anesthesia. In addition, platelet-derived growth factor BB (PDGF-BB) was used to stimulate rat pulmonary artery smooth muscle cells (PASMCs) to construct HPH pathological cell models. The results showed that MSC-Exos could not only reduce the elevation of RVSP, right ventricular hypertrophy and the degree of pulmonary vascular remodeling in HPH rats, but also reduce the proliferation, migration and apoptosis resistance of PASMCs. Finally, GSE53408 and GSE113439 datasets were analyzed and showed that the expression of Hsp90aa1 and pERK/ERK were significantly increased in HPH, also could be inhibited by MSC-Exos. Meanwhile, inhibition of Hsp90aa1 also reduced PASMCs migration and pERK/ERK protein level. In conclusion, MSC-Exos alleviated HPH by suppressing PASMCs proliferation, migration and apoptosis resistance through inhibiting the Hsp90aa1/ERK/pERK pathway.

Fabrication of a low-cost benchtop optical imager for quantum dot microarray-based stress biomarker detection

We report on a simplified optical imager to detect the presence of a stress biomarker protein, namely the Heat shock protein 90 (Hsp90). The imager consists of two elements the optical unit and the sensor, which is a custom-made biochip. Measurement is based on the masking of the streptavidin conjugated quantum dot's (Sav-QDs) fluorescence when Hsp90 attaches to it via biotinylated antibodies (Ab). The masking effect was directly proportional to the Hsp90 concentration. The cost-efficient benchtop imager developed comprises a CMOS sensor, standard optical lenses, and a narrow bandpass filter for optically eliminating background fluorescence. This approach is promising for the realization of cheap, robust, and reliable point-of-care detection systems for various biomarker analyses.

Selective targeting of dipeptidyl-peptidase 4 (DPP-4) positive senescent chondrocyte ameliorates osteoarthritis progression

Senescent cells increase in many tissues with age and induce age-related pathologies, including osteoarthritis (OA). Senescent chondrocytes (SnCs) are found in OA cartilage, and the clearance of those chondrocytes prevents OA progression. However, targeting SnCs is challenging due to the absence of a senescent chondrocyte-specific marker. Therefore, we used flow cytometry to screen and select senescent chondrocyte surface markers and cross-validated with published transcriptomic data. Chondrocytes expressing dipeptidyl peptidase-4 (DPP-4), the selected senescent chondrocyte-specific marker, had multiple senescence phenotypes, such as increased senescence-associated-galactosidase, p16, p21, and senescence-associated secretory phenotype expression, and showed OA chondrocyte phenotypes. To examine the effects of DPP-4 inhibition on DPP-4+ SnCs, sitagliptin, a DPP-4 inhibitor, was treated in vitro. As a result, DPP-4 inhibition selectively eliminates DPP-4+ SnCs without affecting DPP-4- chondrocytes. To assess in vivo therapeutic efficacy of targeting DPP-4+ SnCs, three known senolytics (ABT263, 17DMAG, and metformin) and sitagliptin were comparatively verified in a DMM-induced rat OA model. Sitagliptin treatment specifically and effectively eliminated DPP-4+ SnCs, compared to the other three senolytics. Furthermore, Intra-articular sitagliptin injection to the rat OA model increased collagen type II and proteoglycan expression and physical functions and decreased cartilage destruction, subchondral bone plate thickness and MMP13 expression, leading to the amelioration of OA phenotypes. Collectively, OARSI score was lowest in the sitagliptin treatment group. Taken together, we verified DPP-4 as a surface marker for SnCs and suggested that the selective targeting of DPP-4+ chondrocytes could be a promising strategy to prevent OA progression.

The Role of HSP90 Molecular Chaperones in Depression: Potential Mechanisms

Major depressive disorder (MDD) is characterized by high rates of disability and death and has become a public health problem that threatens human life and health worldwide. HPA axis disorder and neuroinflammation are two common biological abnormalities in MDD patients. Hsp90 is an important molecular chaperone that is widely distributed in the organism. Hsp90 binds to the co-chaperone and goes through a molecular chaperone cycle to complete its regulation of the client protein. Numerous studies have demonstrated that Hsp90 regulates how the HPA axis reacts to stress and how GR, the HPA axis' responsive substrate, matures. In addition, Hsp90 exhibits pro-inflammatory effects that are closely related to neuroinflammation in MDD. Currently, Hsp90 inhibitors have made some progress in the treatment of a variety of human diseases, but they still need to be improved. Further insight into the role of Hsp90 in MDD provides new ideas for the development of new antidepressant drugs targeting Hsp90.

Mutational robustness and the role of buffer genes in evolvability

Organisms rely on mutations to fuel adaptive evolution. However, many mutations impose a negative effect on fitness. Cells may have therefore evolved mechanisms that affect the phenotypic effects of mutations, thus conferring mutational robustness. Specifically, so-called buffer genes are hypothesized to interact directly or indirectly with genetic variation and reduce its effect on fitness. Environmental or genetic perturbations can change the interaction between buffer genes and genetic variation, thereby unmasking the genetic variation's phenotypic effects and thus providing a source of variation for natural selection to act on. This review provides an overview of our understanding of mutational robustness and buffer genes, with the chaperone gene HSP90 as a key example. It discusses whether buffer genes merely affect standing variation or also interact with de novo mutations, how mutational robustness could influence evolution, and whether mutational robustness might be an evolved trait or rather a mere side-effect of complex genetic interactions.

Hsp90α and cell death in cancers: a review

Heat shock protein 90α (Hsp90α), an important molecular chaperone, plays a crucial role in regulating the activity of various intracellular signaling pathways and maintaining the stability of various signaling transduction proteins. In cancer, the expression level of Hsp90α is often significantly upregulated and is recognized as one of the key factors in cancer cell survival and proliferation. Cell death can help achieve numerous purposes, such as preventing aging, removing damaged or infected cells, facilitating embryonic development and tissue repair, and modulating immune response. The expression of Hsp90α is closely associated with specific modes of cell death including apoptosis, necrotic apoptosis, and autophagy-dependent cell death, etc. This review discusses the new results on the relationship between expression of Hsp90α and cell death in cancer. Hsp90α is frequently overexpressed in cancer and promotes cancer cell growth, survival, and resistance to treatment by regulating cell death, rendering it a promising target for cancer therapy.

Gedunin modulates cellular growth and apoptosis in glioblastoma cell lines

BACKGROUND

Glioblastomas are characterized by aggressive behavior. Surgery, radiotherapy, and alkylating agents, including temozolomide are the most common treatment options for glioblastoma. Often, conventional therapies fail to treat these tumors since they develop drug resistance. There is a need for newer agents to combat this deadly tumor. Natural products such as gedunin have shown efficacy in several human diseases. A comprehensive study of gedunin, an heat shock protein (HSP)90 inhibitor, has not been thoroughly investigated in glioblastoma cell lines with different genetic modifications.

AIMS

A key objective of this study was to determine how gedunin affects the biological and signaling mechanisms in glioblastoma cells, and to determine how those mechanisms affect the proliferation and apoptosis of glioblastoma cells.

METHODS

The viability potentials of gedunin were tested using MTT, cell counts, and wound healing assays. Gedunin's effects on glioma cells were further validated using LDH and colony formation assays. In addition, we investigated the survival and apoptotic molecular signaling targets perturbed by gedunin using Western blot analysis and flow cytometry.

RESULTS

Our results show that there was a reduction in cell viability and inhibition of wound healing in the cells tested. Western blot analysis of the gene expression data revealed genes such as EGFR and mTOR/Akt/NF kappa B to be associated with gedunin sensitivity. Gedunin treatment induced apoptosis by cleaving poly ADP-ribose polymerase, activating caspases, and downregulating BCL-xL. Based on these results, gedunin suppressed cell growth and HSP client proteins, resulting in apoptosis in glioblastoma cell lines.

CONCLUSION

Our data provide in vitro support for the anticancer activity of gedunin in glioma cells by downregulating cancer survival proteins.

Trace Element Concentration in the Blood and Aqueous Humor of Subjects with Eye Cataract

Cataract, characterized by the opacification of the lens, is the leading cause of reversible blindness and visual impairment globally. The study aims to investigate the role of trace elements such as Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Se, and Zn in the development and severity of cataract. Elements were quantified by inductively coupled plasma mass spectrometry in blood and aqueous humor of 32 cataract cases and 27 controls living in the Latium region, Italy. The association between element concentration in blood and aqueous humor and cataract severity, gender, and age of subjects were also assessed. Results showed Cr levels significantly elevated in both blood and aqueous humor of cataract cases, with concentrations that increased with cataract severity. In addition, blood Pb levels were significantly higher in older cases and positively correlated with the age of cataract cases, while blood Co and Cu levels negatively correlated with cataract severity, suggesting changes in the levels of these elements. In conclusion, this study provides evidence of the involvement of specific elements in cataract development and severity, and the findings highlighted important avenues for future research. Understanding the biological mechanism underlying element-induced cataract may contribute to preventing cataractogenesis and providing targeted interventions.

The Role of HSP90 and TRAP1 Targets on Treatment in Hepatocellular Carcinoma

Hepatocellular Carcinoma (HCC) is the predominant form of liver cancer and arises due to dysregulation of the cell cycle control machinery. Heat Shock Protein 90 (HSP90) and mitochondrial HSP90, also referred to as TRAP1 are important critical chaperone target receptors for early diagnosis and targeting HCC. Both HSP90 and TRAP1 expression was found to be higher in HCC patients. Hence, the importance of HSP90 and TRAP1 inhibitors mechanism and mitochondrial targeted delivery of those inhibitors function is widely studied. This review also focuses on importance of protein-protein interactions of HSP90 and TRAP1 targets and association of its interacting proteins in various pathways of HCC. To further elucidate the mechanism, systems biology approaches and computational biology approach studies are well explored in the association of inhibition of herbal plant molecules with HSP90 and its mitochondrial type in HCC.

Heat shock proteins as a key defense mechanism in poultry production under heat stress conditions

Over the past years, the poultry industry has been assigned to greater production performance but has become highly sensitive to environmental changes. The average world temperature has recently risen and is predicted to continue rising. In open-sided houses, poultry species confront high outside temperatures, which cause heat stress (HS) problems. Cellular responses are vital in poultry, as they may lead to identifying confirmed HS biomarkers. Heat shock proteins (HSP) are highly preserved protein families that play a significant role in cell function and cytoprotection against various stressors, including HS. The optimal response in which the cell survives the HS elevates HSP levels that prevent cellular proteins from damage caused by HS. The HSP have chaperonic action to ensure that stress-denatured proteins are folded, unfolded, and refolded. The HSP70 and HSP90 are the primary HSP in poultry with a defensive function during HS. HSP70 was the optimal biological marker for assessing HS among the HSP studied. The current review attempts to ascertain the value of HSP as a heat stress defense mechanism in poultry.

Terazosin produces an antidepressant-like effect in mice exposed to chronic unpredictable mild stress behavioral alteration

Terazosin is an α1-adrenergic receptor antagonist that can relax smooth muscle and is prescribed to treat benign prostatic hyperplasia and, rarely, hypertension. The present study investigated the antidepressant-like actions of terazosin (TZ) in mice. They were first subjected to chronic unpredictable mild stress (CUMS) and then the effects of TZ were assessed using the forced swimming test (FST) and tail suspension test (TST), sucrose preference test (SPT), actophotometer test (APT). The changes in the PGK1 levels, neurotransmitters, and proinflammatory cytokines levels after chronic stress and TZ treatment were examined. It was found that TZ exhibited an antidepressant-like effect in the FST, TST, SPT, and APT. It was effective in the CUMS model of depression. It was also found that TZ treatment reduced the levels of proinflammatory cytokines and elevated the neurotransmitter levels in mice. Results of this study suggest that TZ has antidepressant-like actions in mice models of CUMS induced depression.

Environmental and molecular regulation of diapause formation in a scyphozoan jellyfish

Understanding the mechanisms underlying diapause formation is crucial for gaining insight into adaptive survival strategies across various species. In this study, we aimed to uncover the pivotal role of temperature and food availability in regulating diapausing podocyst formation in the jellyfish Aurelia coerulea. Furthermore, we explored the cellular and molecular basis of diapause formation using single-cell RNA sequencing. Our results showed cell-type-specific transcriptional landscapes during podocyst formation, which were underscored by the activation of specific transcription factors and signalling pathways. In addition, we found that the heat shock protein-coding genes HSC70 and HSP90a potentially act as hub genes that regulate podocyst formation. Finally, we mapped the single-cell atlas of diapausing podocysts and identified cell types involved in metabolism, environmental sensing, defence and development that may collectively contribute to the long-term survival and regulated excystment of diapausing podocysts. Taken together, the findings of this study provide novel insights into the molecular mechanisms that regulate diapause formation and contributes to a better understanding of adaptive survival strategies in a variety of ecological contexts.

Heat Shock Protein 90 in Parkinson's Disease: Profile of a Serial Killer

Parkinson's disease (PD) is the second most common neurodegenerative disease, characterized by abnormal α-synuclein misfolding and aggregation, mitochondrial dysfunction, oxidative stress, as well as progressive death of dopaminergic neurons in the substantia nigra. Molecular chaperones play a role in stabilizing proteins and helping them achieve their proper structure. Previous studies have shown that overexpression of heat shock protein 90 (HSP90) can lead to the death of dopaminergic neurons associated with PD. Inhibiting HSP90 is considered a potential treatment approach for neurodegenerative disorders, as it may reduce protein aggregation and related toxicity, as well as suppress various forms of regulated cell death (RCD). This review provides an overview of HSP90 and its role in PD, focusing on its modulation of proteostasis and quality control of LRRK2. The review also explores the effects of HSP90 on different types of RCD, such as apoptosis, chaperone-mediated autophagy (CMA), necroptosis, and ferroptosis. Additionally, it discusses HSP90 inhibitors that have been tested in PD models. We will highlight the under-investigated neuroprotective effects of HSP90 inhibition, including modulation of oxidative stress, mitochondrial dysfunction, PINK/PARKIN, heat shock factor 1 (HSF1), histone deacetylase 6 (HDAC6), and the PHD2-HSP90 complex-mediated mitochondrial stress pathway. By examining previous literature, this review uncovers overlooked neuroprotective mechanisms and emphasizes the need for further research on HSP90 inhibitors as potential therapeutic strategies for PD. Finally, the review discusses the potential limitations and possibilities of using HSP90 inhibitors in PD therapy.

Functionalized Nanomaterials for Inhibiting ATP-Dependent Heat Shock Proteins in Cancer Photothermal/Photodynamic Therapy and Combination Therapy

Phototherapies induced by photoactive nanomaterials have inspired and accentuated the importance of nanomedicine in cancer therapy in recent years. During these light-activated cancer therapies, a nanoagent can produce heat and cytotoxic reactive oxygen species by absorption of light energy for photothermal therapy (PTT) and photodynamic therapy (PDT). However, PTT is limited by the self-protective nature of cells, with upregulated production of heat shock proteins (HSP) under mild hyperthermia, which also influences PDT. To reduce HSP production in cancer cells and to enhance PTT/PDT, small HSP inhibitors that can competitively bind at the ATP-binding site of an HSP could be employed. Alternatively, reducing intracellular glucose concentration can also decrease ATP production from the metabolic pathways and downregulate HSP production from glucose deprivation. Other than reversing the thermal resistance of cancer cells for mild-temperature PTT, an HSP inhibitor can also be integrated into functionalized nanomaterials to alleviate tumor hypoxia and enhance the efficacy of PDT. Furthermore, the co-delivery of a small-molecule drug for direct HSP inhibition and a chemotherapeutic drug can integrate enhanced PTT/PDT with chemotherapy (CT). On the other hand, delivering a glucose-deprivation agent like glucose oxidase (GOx) can indirectly inhibit HSP and boost the efficacy of PTT/PDT while combining these therapies with cancer starvation therapy (ST). In this review, we intend to discuss different nanomaterial-based approaches that can inhibit HSP production via ATP regulation and their uses in PTT/PDT and cancer combination therapy such as CT and ST.

Glucose-regulated protein 94 facilitates the proliferation of the Bombyx mori nucleopolyhedrovirus via inhibiting apoptosis

Glucose regulatory protein 94 (GRP94) is an endoplasmic reticulum (ER)-resident member of the heat shock protein 90 (HSP90) family, that plays an important role in secreted protein folding. Bombyx mori nuclear polyhedrosis virus (BmNPV) is one of the main pathogens in sericulture, causing serious economic losses every year. Previous studies showed that HSP90 members promote BmNPV replication in silkworm, but the function of BmGRP94 in BmNPV infection and proliferation is still not understood. In this study, we investigated the interplay between BmGRP94 and BmNPV infection in silkworm. We first identified a single gene of BmGRP94 in the Bombyx mori genome, which encodes a polypeptide with 810 amino acids in length. Spatio-temporal expression profiles showed that BmGRP94 was highly expressed in hemocytes and midgut, and was significantly induced by BmNPV infection. Furthermore, overexpression of BmGRP94 facilitates viral proliferation, while BmGRP94 inhibition evidently decreased BmNPV proliferation in BmN cells and in silkworm midgut. Mechanistically, BmGRP94 inhibition triggers ER stress, as judged by increased expression of PERK/ATF4/ERO1, H2O2 production, and ER calcium efflux, which promotes cell apoptosis to restrict BmNPV replication in silkworm. These results suggest that BmGRP94 plays an important role in facilitating BmNPV proliferation, and provides a potential molecular target for BmNPV prevention.

Casuarina glauca branchlets' extract as a potential treatment for ulcerative colitis: chemical composition, in silico and in vivo studies

Ulcerative colitis (UC) is an inflammatory bowel disease that is often resistant to current treatment options, leading to a need for alternative therapies. Herbal products have shown promise in managing various conditions, including UC. However, the potential of Casuarina glauca branchlets ethanolic extract (CGBRE) in treating UC has not been explored. This study aimed to analyze the chemical composition of CGBRE and evaluate its efficacy in UC treatment through in silico and in vivo experiments. LC-ESI-MS/MS was used to identify 86 compounds in CGBRE, with 21 potential bioactive compounds determined through pharmacokinetic analysis. Network pharmacology analysis revealed 171 potential UC targets for the bioactive compounds, including EGFR, LRRK2, and HSP90 as top targets, which were found to bind to key CGBRE compounds through molecular docking. Molecular docking findings suggested that CGBRE may be effective in the prevention or treatment of ulcerative colitis mediated by these proteins, where key CGBRE compounds exhibited good binding affinities through formation of numerous interactions. In vivo studies in rats with acetic acid-induced UC demonstrated that oral administration of 300 mg/kg CGBRE for 6 days reduced UC symptoms and colonic expression of EGFR, LRRK2, and HSP90. These findings supported the therapeutic potential of CGBRE in UC and suggested the need for further preclinical and clinical investigation.

Susceptibility to caspofungin is regulated by temperature and is dependent on calcineurin in Candida albicans

IMPORTANCE

Echinocandins are the newest antifungal drugs and are first-line treatment option for life-threatening systemic infections. Due to lack of consensus regarding what temperature should be used when evaluating susceptibility of yeasts to echinocandins, typically either 30°C, 35°C, or 37°C is used. However, the impact of temperature on antifungal efficacy of echinocandins is unexplored. In the current study, we demonstrated that Candida albicans laboratory strain SC5314 was more susceptible to caspofungin at 37°C than at 30°C. We also found that calcineurin was required for temperature-modulated caspofungin susceptibility. Surprisingly, the altered caspofungin susceptibility was not due to differential expression of some canonical genes such as FKS, CHS, or CHT genes. The molecular mechanism of temperature-modulated caspofungin susceptibility is undetermined and deserves further investigations.

Muscle Transcriptome Sequencing Revealed Thermal Stress-Responsive Regulatory Genes in Farmed Rohu, Labeo rohita (Hamilton, 1822)

Rohu, Labeo rohita, is one of the most important aquaculture species in the Indian subcontinent. Understanding the molecular-level physiological responses to thermal stress or climate change is essential. In the present work, transcriptome sequencing was carried out in the muscle tissue of the rohu in response to heat stress (35 °C) in comparison with the control (28 °C). A total of 125 Gb of sequence data was generated, and the raw-reads were filtered and trimmed, which resulted in 484 million quality reads. Reference-based assembly of reads was performed using L. rohita genome, and a total of 90.17% of reads were successfully mapped. A total of 37,462 contigs were assembled with an N50 value of 1854. The differential expression analysis revealed a total of 107 differentially expressed genes (DEGs) (15 up-, 37 down-, and 55 neutrally regulated) as compared to the control group (Log2FC > 2, P < 0.05). Gene enrichment analysis of DEGs indicates that transcripts were associated with molecular, biological, and cellular activities. The randomly selected differentially expressed transcripts were validated by RT-qPCR and found consistent expression patterns in line with the RNA-seq data. Several transcripts such as SERPINE1(HSP47), HSP70, HSP90alpha, Rano class II histocompatibility A beta, PGC-1 and ERR-induced regulator, proto-oncogene c-Fos, myozenin2, alpha-crystallin B chain-like protein, angiopoietin-like protein 8, and acetyl-CoA carboxylases have been identified in muscle tissue of rohu that are associated with stress/immunity. This study identified the key biomarker SERPINE1 (HSP47), which showed significant upregulation (~ 2- to threefold) in muscle tissue of rohu exposed to high temperature. This study can pave a path for the identification of stress-responsive biomarkers linked with thermal adaptations in the farmed carps.

Evaluation of histologic, antiapoptotic and antioxidant effects of melatonin against the acute ocular toxicity of Cisplatin

This study aimed to investigate the protective effect of melatonin against the acute toxicity of cisplatin in ocular tissues. The eyes of 40 rats were divided into 4 groups: Control group (10 rats), Melatonin (Mel) group (10 rats), Cisplatin (Cis) group (10 rats), Melatonin (Mel) + Cisplatin (Cis) group (10 rats). Retina, cornea, and ciliary body tissues were examined after hematoxylin-eosin staining of sections obtained from the eyes and were scored for disorganization and degeneration. Apoptotic cells were counted for the retina, cornea, and ciliary body with the TUNEL (Terminal deoxynucleotidyl transferase dUTP nick end labeling) method. The total antioxidant status (TAS) / total oxidant status (TOS) of homogenized eye tissues were measured. While apoptotic cells were found to increase in the cornea of the Cisplatin (Cis) group, no difference was found regarding the retina and ciliary body cell count. An increased number of apoptotic cells in the cornea of the Cis group was found while there was a decrease in the group where Cisplatin and Melatonin were administered together (Mel+Cis group). There was no statistically significant difference amongst groups for TOS or TAS. Melatonin had a partial protective effect against histological damage.

Regulation of PGC-1α of the Mitochondrial Energy Metabolism Pathway in the Gills of Indian Medaka (Oryzias dancena) under Hypothermal Stress

Ectothermic fish exposure to hypothermal stress requires adjusting their metabolic molecular machinery, which was investigated using Indian medaka (Oryzias dancena; 10 weeks old, 2.5 ± 0.5 cm) cultured in fresh water (FW) and seawater (SW; 35‱) at room temperature (28 ± 1 °C). The fish were fed twice a day, once in the morning and once in the evening, and the photoperiod was 12 h:12 h light: dark. In this study, we applied two hypothermal treatments to reveal the mechanisms of energy metabolism via pgc-1α regulation in the gills of Indian medaka; cold-stress (18 °C) and cold-tolerance (extreme cold; 15 °C). The branchial ATP content was significantly higher in the cold-stress group, but not in the cold-tolerance group. In FW- and SW-acclimated medaka, the expression of genes related to mitochondrial energy metabolism, including pgc-1α, prc, Nrf2, tfam, and nd5, was analyzed to illustrate differential responses of mitochondrial energy metabolism to cold-stress and cold-tolerance environments. When exposed to cold-stress, the relative mRNA expression of pgc-1α, prc, and Nrf2 increased from 2 h, whereas that of tfam and nd5 increased significantly from 168 h. When exposed to a cold-tolerant environment, prc was significantly upregulated at 2 h post-cooling in the FW and SW groups, and pgc-1α was significantly upregulated at 2 and 12 h post-cooling in the FW group, while tfam and nd5 were downregulated in both FW and SW fish. Hierarchical clustering revealed gene interactions in the cold-stress group, which promoted diverse mitochondrial energy adaptations, causing an increase in ATP production. However, the cold-tolerant group demonstrated limitations in enhancing ATP levels through mitochondrial regulation via the PGC-1α energy metabolism pathway. These findings suggest that ectothermic fish may develop varying degrees of thermal tolerance over time in response to climate change. This study provides insights into the complex ways in which fish adjust their metabolism when exposed to cold stress, contributing to our knowledge of how they adapt.

The role of molecular chaperones in the mechanisms of epileptogenesis

Epilepsy is a group of neurological diseases which requires significant economic costs for the treatment and care of patients. The central point of epileptogenesis stems from the failure of synaptic signal transmission mechanisms, leading to excessive synchronous excitation of neurons and characteristic epileptic electroencephalogram activity, in typical cases being manifested as seizures and loss of consciousness. The causes of epilepsy are extremely diverse, which is one of the reasons for the complexity of selecting a treatment regimen for each individual case and the high frequency of pharmacoresistant cases. Therefore, the search for new drugs and methods of epilepsy treatment requires an advanced study of the molecular mechanisms of epileptogenesis. In this regard, the investigation of molecular chaperones as potential mediators of epileptogenesis seems promising because the chaperones are involved in the processing and regulation of the activity of many key proteins directly responsible for the generation of abnormal neuronal excitation in epilepsy. In this review, we try to systematize current data on the role of molecular chaperones in epileptogenesis and discuss the prospects for the use of chemical modulators of various chaperone groups' activity as promising antiepileptic drugs.

Potential role of miR-8159-x in heat stress response in rainbow trout (Oncorhynchus mykiss)

Rainbow trout (Oncorhynchus mykiss) is a representative species of cold-water fish. Elevated temperatures during summer often result in significant high mortality rates. MicroRNAs (miRNAs) are class of small non-coding RNAs that play a crucial role as post-transcriptional regulators in various biological processes. Emerging evidence suggests that miRNAs are important regulators role during heat stress. Analyzing previously obtained miRNA-sequencing data, we observed substantial down regulation of miR-8159-x in the liver tissue of heat stressed rainbow trout. In this study, we conducted a dual luciferase reporter assay to validate that miR-8159-x target, a key gene involved in heat stress in rainbow trout. By examining the expression patterns of miR-8159-x and hsp90a1 in the liver tissue at 18 °C (CG) and 24 °C (HS) groups, we propose that miR-8159-x may negatively regulate hsp90a1. Furthermore, in vitro hepatocyte assay, transfection with miR-8159-x mimics significantly reduced the expression level of hsp90a1, whereas transfection with a miR-8159-x inhibitor yielded the opposite effect. Additionally, overexpression of miR-8159-x inhibited cell proliferation and induced apoptosis in normal rainbow trout hepatocytes. We further investigated the effects of miR-8159-x overexpression or inhibition on the mRNA and protein levels of the target gene hsp90a1 under heat stress conditions. In conclusion, our findings suggest that miR-8159-x participates in the biological response to heat stress by targeting hsp90a1. These results contribute to a better understanding of the molecular mechanisms underlying heat stress in rainbow trout and provide valuable insights for future research.

Worth the Weight: Sub-Pocket EXplorer (SubPEx), a Weighted Ensemble Method to Enhance Binding-Pocket Conformational Sampling

Structure-based virtual screening (VS) is an effective method for identifying potential small-molecule ligands, but traditional VS approaches consider only a single binding-pocket conformation. Consequently, they struggle to identify ligands that bind to alternate conformations. Ensemble docking helps address this issue by incorporating multiple conformations into the docking process, but it depends on methods that can thoroughly explore pocket flexibility. We here introduce Sub-Pocket EXplorer (SubPEx), an approach that uses weighted ensemble (WE) path sampling to accelerate binding-pocket sampling. As proof of principle, we apply SubPEx to three proteins relevant to drug discovery: heat shock protein 90, influenza neuraminidase, and yeast hexokinase 2. SubPEx is available free of charge without registration under the terms of the open-source MIT license: http://durrantlab.com/subpex/.

Heat shock proteins in cancer - Known but always being rediscovered: Their perspectives in cancer immunotherapy

Heat shock proteins (HSPs) represent cellular chaperones that are classified into several families, including HSP27, HSP40, HSP60, HSP70, and HSP90. The role of HSPs in the cell includes the facilitation of protein folding and maintaining protein structure. Both processes play crucial roles during stress conditions in the cell such as heat shock, degradation, and hypoxia. Moreover, HSPs are important modulators of cellular proliferation and differentiation, and are strongly associated with the molecular orchestration of carcinogenesis. The expression and/or activity of HSPs in cancer cells is generally abnormally high and is associated with increased metastatic potential and activity of cancer stem cells, more pronounced angiogenesis, downregulated apoptosis, and the resistance to anticancer therapy in many patients. Based on the mentioned reasons, HSPs have strong potential as valid diagnostic, prognostic, and therapeutic biomarkers in clinical oncology. In addition, numerous papers describe the role of HSPs as chaperones in the regulation of immune responses inside and outside the cell. Importantly, highly expressed/activated HSPs may be inhibited via immunotherapeutic targets in various types of cancers. The aim of this work is to provide a comprehensive overview of the relationship between HSPs and the tumor cell with the intention of highlighting the potential use of HSPs in personalized cancer management.

HSP90/CDC37 inactivation promotes degradation of LKB1 protein to suppress AMPK signaling in bronchial epithelial cells exposed to sulfur mustard analog, 2-chloroethyl ethyl sulfide

To investigate the role of the liver kinase (LK) B1 protein, an activator of AMP-activated protein kinase (AMPK), in AMPK signaling suppression when exposed to vesicant, a kind of chemical warfare agent. Cultured human bronchial epithelial cells were inflicted with sulfur mustard (SM) analog, 2-chloroethyl ethyl sulfide (CEES) of 0.2-1.0 mM concentration, and cell proliferation, apoptosis, autophagy, and cellular ATP level were analyzed up to 24 h after the exposure. Focusing on LKB1, heat shock protein (HSP) 90, and cell division cycle (CDC) 37 proteins, the protein expression, phosphorylation, and interaction were examined with western blot, immunofluorescence staining, and/or immunoprecipitation. AMPK signaling was found to be inhibited 24 h after being exposed to either sub-cytotoxic (0.5 mM) or cytotoxic (1.0 mM) concentration of CEES based on MTS assay. Consistently, the degradation of the LKB1 protein and its less interaction with the HSP90/CDC37 complex was confirmed. It was found that 1.0, not 0.5 mM CEES also decreased the CDC37 protein, proteasome activity, and cellular ATP content that modulates HSP90 protein conformation. Inhibiting proteasome activity could alternatively activate autophagy. Finally, either 0.5 or 1.0 mM CEES activated HSP70 and autophagy, and the application of an HSP70 inhibitor blocked autophagy and autophagic degradation of the LKB1 protein. In conclusion, we reported here that AMPK signaling inactivation by CEES was a result of LKB1 protein loss via less protein complex formation and enhanced degradation.

An acute respiratory distress syndrome drug development collaboration stimulated by the Virginia Drug Discovery Consortium

The genesis of most older medicinal agents has generally been empirical. During the past one and a half centuries, at least in the Western countries, discovering and developing drugs has been primarily the domain of pharmaceutical companies largely built upon concepts emerging from organic chemistry. Public sector funding for the discovery of new therapeutics has more recently stimulated local, national, and international groups to band together and focus on new human disease targets and novel treatment approaches. This Perspective describes one contemporary example of a newly formed collaboration that was simulated by a regional drug discovery consortium. University of Virginia, Old Dominion University, and a university spinout company, KeViRx, Inc., partnered under a NIH Small Business Innovation Research grant, to produce potential therapeutics for acute respiratory distress syndrome resulting from the ongoing COVID-19 pandemic.

circSLC4A7 accelerates stemness and progression of gastric cancer by interacting with HSP90 to activate NOTCH1 signaling pathway

Gastric cancer stem cells (GCSCs) play critical roles in gastric cancer (GC) initiation and development. Circular RNAs (circRNAs) participate in diverse cancer biological processes and function as tumor suppressors or oncogenes. This study aims to discover the expression profile and functional roles of circRNAs in GCSCs. A spheroid formation assay was conducted to enrich GCSCs. Genome-wide sequencing of circRNAs showed that a novel circRNA, circSLC4A7, was one of the most upregulated circRNAs in GCSCs. CircSLC4A7 was localized to the nucleus, and its level was elevated in GC cells and tissues. Furthermore, circSLC4A7 increased CSC-like properties and drove cell proliferation, migration, and invasion, which were determined by gain- and loss-of-function experiments. Specific circRNA pull-down assays followed by mass spectrometry analysis, RNA immunoprecipitation, and dual RNA-fluorescence in situ hybridization and immunofluorescence assay were conducted and HSP90 was detected to interact with circSLC4A7 and mediate the oncogenic function of circSLC4A7 by activating the Notch1 signaling pathway in GC. This study highlights a novel oncogenic function of circSLC4A7 mediated by its binding with HSP90 and thus activating the Notch1 signaling pathway.

Novel cancer treatment paradigm targeting hypoxia-induced factor in conjunction with current therapies to overcome resistance

Chemotherapy, radiotherapy, targeted therapy, and immunotherapy are established cancer treatment modalities that are widely used due to their demonstrated efficacy against tumors and favorable safety profiles or tolerability. Nevertheless, treatment resistance continues to be one of the most pressing unsolved conundrums in cancer treatment. Hypoxia-inducible factors (HIFs) are a family of transcription factors that regulate cellular responses to hypoxia by activating genes involved in various adaptations, including erythropoiesis, glucose metabolism, angiogenesis, cell proliferation, and apoptosis. Despite this critical function, overexpression of HIFs has been observed in numerous cancers, leading to resistance to therapy and disease progression. In recent years, much effort has been poured into developing innovative cancer treatments that target the HIF pathway. Combining HIF inhibitors with current cancer therapies to increase anti-tumor activity and diminish treatment resistance is one strategy for combating therapeutic resistance. This review focuses on how HIF inhibitors could be applied in conjunction with current cancer treatments, including those now being evaluated in clinical trials, to usher in a new era of cancer therapy.

Development of the first geldanamycin-based HSP90 degraders

Despite the early clinical promise, adverse events such as acquired resistance and dose-limiting toxicities have barred the widespread use of HSP90 inhibitors as anticancer drugs. A new approach involving proteolysis-targeting chimeras (PROTACs) to degrade the protein instead of inhibiting it may overcome these problems. In this work, we describe the design, synthesis, and evaluation of cereblon-recruiting geldanamycin-based HSP90 degraders based on the PROTAC technology. Our best degrader, 3a, effectively decreased HSP90α and HSP90β levels in cells utilizing the ubiquitin-proteasome pathway.

The Landscapes of Gluten Regulatory Network in Elite Wheat Cultivars Contrasting in Gluten Strength

Yangmai-13 (YM13) is a wheat cultivar with weak gluten fractions. In contrast, Zhenmai-168 (ZM168) is an elite wheat cultivar known for its strong gluten fractions and has been widely used in a number of breeding programs. However, the genetic mechanisms underlying the gluten signatures of ZM168 remain largely unclear. To address this, we combined RNA-seq and PacBio full-length sequencing technology to unveil the potential mechanisms of ZM168 grain quality. A total of 44,709 transcripts were identified in Y13N (YM13 treated with nitrogen) and 51,942 transcripts in Z168N (ZM168 treated with nitrogen), including 28,016 and 28,626 novel isoforms in Y13N and Z168N, respectively. Five hundred and eighty-four differential alternative splicing (AS) events and 491 long noncoding RNAs (lncRNAs) were discovered. Incorporating the sodium-dodecyl-sulfate (SDS) sedimentation volume (SSV) trait, both weighted gene coexpression network analysis (WGCNA) and multiscale embedded gene coexpression network analysis (MEGENA) were employed for network construction and prediction of key drivers. Fifteen new candidates have emerged in association with SSV, including 4 transcription factors (TFs) and 11 transcripts that partake in the post-translational modification pathway. The transcriptome atlas provides new perspectives on wheat grain quality and would be beneficial for developing promising strategies for breeding programs.

Worth the weight: Sub-Pocket EXplorer (SubPEx), a weighted-ensemble method to enhance binding-pocket conformational sampling

Structure-based virtual screening (VS) is an effective method for identifying potential small-molecule ligands, but traditional VS approaches consider only a single binding-pocket conformation. Consequently, they struggle to identify ligands that bind to alternate conformations. Ensemble docking helps address this issue by incorporating multiple conformations into the docking process, but it depends on methods that can thoroughly explore pocket flexibility. We here introduce Sub-Pocket EXplorer (SubPEx), an approach that uses weighted ensemble (WE) path sampling to accelerate binding-pocket sampling. As proof of principle, we apply SubPEx to three proteins relevant to drug discovery: heat shock protein 90, influenza neuraminidase, and yeast hexokinase 2. SubPEx is available free of charge without registration under the terms of the open-source MIT license: http://durrantlab.com/subpex/.

The chaperone system in cancer therapies: Hsp90

The chaperone system (CS) of an organism is composed of molecular chaperones, chaperone co-factors, co-chaperones, and chaperone receptors and interactors. It is present throughout the body but with distinctive features for each cell and tissue type. Previous studies pertaining to the CS of the salivary glands have determined the quantitative and distribution patterns for several members, the chaperones, in normal and diseased glands, focusing on tumors. Chaperones are cytoprotective, but can also be etiopathogenic agents causing diseases, the chaperonopathies. Some chaperones such as Hsp90 potentiate tumor growth, proliferation, and metastasization. Quantitative data available on this chaperone in salivary gland tissue with inflammation, and benign and malignant tumors suggest that assessing tissue Hsp90 levels and distribution patterns is useful for differential diagnosis-prognostication, and patient follow up. This, in turn, will reveal clues for developing specific treatment centered on the chaperone, for instance by inhibiting its pro-carcinogenic functions (negative chaperonotherapy). Here, we review data on the carcinogenic mechanisms of Hsp90 and their inhibitors. Hsp90 is the master regulator of the PI3K-Akt-NF-kB axis that promotes tumor cell proliferation and metastasization. We discuss pathways and interactions involving these molecular complexes in tumorigenesis and review Hsp90 inhibitors that have been tested in search of an efficacious anti-cancer agent. This targeted therapy deserves extensive investigation in view of its theoretical potential and some positive practical results and considering the need of novel treatments for tumors of the salivary glands as well as other tissues.

Post-Transcriptional and Post-Translational Modifications in Telomerase Biogenesis and Recruitment to Telomeres

Telomere length is associated with the proliferative potential of cells. Telomerase is an enzyme that elongates telomeres throughout the entire lifespan of an organism in stem cells, germ cells, and cells of constantly renewed tissues. It is activated during cellular division, including regeneration and immune responses. The biogenesis of telomerase components and their assembly and functional localization to the telomere is a complex system regulated at multiple levels, where each step must be tuned to the cellular requirements. Any defect in the function or localization of the components of the telomerase biogenesis and functional system will affect the maintenance of telomere length, which is critical to the processes of regeneration, immune response, embryonic development, and cancer progression. An understanding of the regulatory mechanisms of telomerase biogenesis and activity is necessary for the development of approaches toward manipulating telomerase to influence these processes. The present review focuses on the molecular mechanisms involved in the major steps of telomerase regulation and the role of post-transcriptional and post-translational modifications in telomerase biogenesis and function in yeast and vertebrates.

Posttranslational regulation of liver kinase B1 (LKB1) in human cancer

Liver kinase B1 (LKB1) is a serine-threonine kinase that participates in multiple cellular and biological processes, including energy metabolism, cell polarity, cell proliferation, cell migration, and many others. LKB1 is initially identified as a germline-mutated causative gene in Peutz-Jeghers syndrome (PJS) and is commonly regarded as a tumor suppressor due to frequent inactivation in a variety of cancers. LKB1 directly binds and activates its downstream kinases including the AMP-activated protein kinase (AMPK) and AMPK-related kinases by phosphorylation, which has been intensively investigated for the past decades. An increasing number of studies has uncovered the posttranslational modifications (PTMs) of LKB1 and consequent changes in its localization, activity, and interaction with substrates. The alteration in LKB1 function as a consequence of genetic mutations and aberrant upstream signaling regulation leads to tumor development and progression. Here, we review current knowledge about the mechanism of LKB1 in cancer and the contributions of PTMs, such as phosphorylation, ubiquitination, SUMOylation, acetylation, prenylation, and others, to the regulation of LKB1 function, offering new insights into the therapeutic strategies in cancer.

Dose-dependent manner of luteolin in the modulation of spatial memory with respect to the hippocampal level of HSP70 and HSP90 in sleep-deprived rats

Sleep deprivation (SD) induces a variety of deleterious effects on different cognitive functions such as memory. Elevated neuroinflammation, oxidative stress, and apoptosis, and decreased synaptic plasticity and antioxidant capacity are involved in the deleterious effects of SD on memory. On the other hand, luteolin (a flavonoid compound) has antioxidant, neuroprotective, and anti-inflammatory properties. Also, Heat shock protein 70 (HSP70) and Heat shock protein 90 (HSP90) can be involved in modulating memory. In this study, we aimed to assess the effects of SD and luteolin on spatial learning and memory using Morris Water Maze apparatus in rats, with respect to the level of HSP70 and HSP90 in the hippocampus. Luteolin was injected intracerebroventricular (i.c.v.) at the doses of 0.5, 1, and 2 µg/rat. The results showed that SD impaired spatial memory, while luteolin dose-dependently restored SD-induced spatial memory impairment. SD increased the expression level of HSP90 in the hippocampus, whereas luteolin dose-dependently reversed the effect of SD. Furthermore, SD decreased the expression level of HSP70 protein in the hippocampus, while luteolin dose-dependently reversed the effect of SD. In conclusion, HSP70 and HSP90 may be involved in the deleterious effect of SD on memory, and in the improvement effect of luteolin on memory. This is a novel study reporting novel data and we suggest further detailed studies to better understand the interactions between SD, luteolin, and Heat shock proteins.

Lipoprotein Metabolism, Protein Aggregation, and Alzheimer's Disease: A Literature Review

Alzheimer's disease (AD) is the most common form of dementia. The physiopathology of AD is well described by the presence of two neuropathological features: amyloid plaques and tau neurofibrillary tangles. In the last decade, neuroinflammation and cellular stress have gained importance as key factors in the development and pathology of AD. Chronic cellular stress occurs in degenerating neurons. Stress Granules (SGs) are nonmembranous organelles formed as a response to stress, with a protective role; however, SGs have been noted to turn into pathological and neurotoxic features when stress is chronic, and they are related to an increased tau aggregation. On the other hand, correct lipid metabolism is essential to good function of the brain; apolipoproteins are highly associated with risk of AD, and impaired cholesterol efflux and lipid transport are associated with an increased risk of AD. In this review, we provide an insight into the relationship between cellular stress, SGs, protein aggregation, and lipid metabolism in AD.

Oligodendrocyte Progenitors Display Enhanced Proliferation and Autophagy after Space Flight

Intracranial hypertension (ICP) and visual impairment intracranial pressure (VIIP) are some of the consequences of long-term space missions. Here we examined the behavior of oligodendrocyte progenitors (OLPs) after space flight using time-lapse microscopy. We show that most OLPs divided more than ground control (GC) counterparts did. Nonetheless, a subpopulation of OLPs flown to space presented a significant increase in autophagic cell death. Examination of the proteomic profile of the secretome of space flown OLPs (SPC-OLPs) revealed that the stress protein heat shock protein-90 beta "HSP-90β" was the 5th most enriched (6.8 times) and the secreted protein acidic and rich in cysteine "SPARC" was the 7th most enriched (5.2 times), with respect to ground control cells. SPARC induces endoplasmic reticulum stress, which leads to autophagy. Given the roles and importance of these two proteins in mammalian cells' metabolism, their upregulation may hold the key to modulating cell proliferation and autophagy, in order to mitigate ICP and VIIP during and after space missions.

Biochemical, transcriptomic and metabolomic responses to total dissolved gas supersaturation and their underlying molecular mechanisms in Yangtze sturgeon (Acipenser dabryanus)

With the rapid development of hydropower facility construction, the total dissolved gas (TDG) generated by dam discharge is seriously threatening the survival of fish and has become an ecological environmental issue of global concern. However, how TDG affects fish physiology and the underlying molecular mechanism remain poorly known. In this study, Acipenser dabryanus, an ancient living fossil that is a flagship species of the Yangtze River, was exposed to water supersaturated with TDG at a level of 116% for 48 h. A comprehensive analysis was performed to study the effect of TDG supersaturation stress on A. dabryanus, including histopathological, biochemical, transcriptomic and metabolomic analyses. The histopathological results showed that mucosal-associated lymphoid tissues were seriously damaged after TDG supersaturation stress. Plasma catalase levels increased significantly under TDG supersaturation stress, while superoxide dismutase levels decreased significantly. Transcriptomic analysis revealed 289 upregulated genes and 162 downregulated genes in gill tissue and 535 upregulated and 104 downregulated genes in liver tissue. Metabolomic analysis revealed 63 and 164 differentially abundant metabolites between the control group and TDG group in gill and liver, respectively. The majority of heat shock proteins and genes related to ubiquitin and various immune-related pathways were significantly upregulated by TDG supersaturation stress. Integrated transcriptomic and metabolomic analyses revealed the upregulation of amino acid metabolism and glycometabolism pathways under TDG supersaturation stress. Glycerophospholipid metabolism was increased which might be associated with maintaining cell membrane integrity. This is the first study revealing the underlying molecular mechanisms of effects of TDG supersaturation on fish. Our results suggested that acute TDG supersaturation stress could enhance immune and antioxidative functions and activate energy metabolic pathways as an adaptive mechanism in A. dabryanus.

In silico approaches uncovering the systematic function of N-phosphorylated proteins in human cells

Phosphorylation plays a key role in the regulation of protein function. In addition to the extensively studied O-phosphorylation of serine, threonine, and tyrosine, emerging evidence suggests that the non-canonical phosphorylation of histidine, lysine, and arginine termed N-phosphorylation, exists widely in eukaryotes. At present, the study of N-phosphorylation is still in its infancy, and its regulatory role and specific biological functions in mammalian cells are still unknown. Here, we report the in silico analysis of the systematic biological significance of N-phosphorylated proteins in human cells. The protein structural and functional domain enrichment analysis revealed that N-phosphorylated proteins are rich in RNA recognition motif, nucleotide-binding and alpha-beta plait domains. The most commonly enriched biological pathway is the metabolism of RNA. Besides, arginine phosphorylated (pArg) proteins are highly related to DNA repair, while histidine phosphorylated (pHis) proteins may play a role in the regulation of the cell cycle, and lysine phosphorylated (pLys) proteins are linked to cellular stress response, intracellular signal transduction, and intracellular transport, which are of great significance for maintaining cell homeostasis. Protein-protein interaction (PPI) network analysis revealed important hub proteins (i.e., SRSF1, HNRNPA1, HNRNPC, SRSF7, HNRNPH1, SRSF2, SRSF11, HNRNPD, SRRM2 and YBX1) which are closely related to neoplasms, nervous system diseases, and virus infection and have potential as therapeutic targets. Those proteins with clinical significance are worthy of attention, and the rational considerations of N-phosphorylation in occurrence and progression of diseases might be beneficial for further translational applications.

Proteostasis in aging-associated ocular disease

Vision impairment has devastating consequences for the quality of human life. The cells and tissues associated with the visual process must function throughout one's life span and maintain homeostasis despite exposure to a variety of insults. Maintenance of the proteome is termed proteostasis, and is vital for normal cellular functions, especially at an advanced age. Here we describe basic aspects of proteostasis, from protein synthesis and folding to degradation, and discuss the current status of the field with a particular focus on major age-related eye diseases: age-related macular degeneration, cataract, and glaucoma. Our intent is to allow vision scientists to determine where and how to harness the proteostatic machinery for extending functional homeostasis in the aging retina, lens, and trabecular meshwork. Several common themes have emerged despite these tissues having vastly different metabolisms. Continued exposure to insults, including chronic stress with advancing age, increases proteostatic burden and reduces the fidelity of the degradation machineries including the ubiquitin-proteasome and the autophagy-lysosome systems that recognize and remove damaged proteins. This "double jeopardy" results in an exponential accumulation of cytotoxic proteins with advancing age. We conclude with a discussion of the challenges in maintaining an appropriate balance of protein synthesis and degradation pathways, and suggest that harnessing proteostatic capacities should provide new opportunities to design interventions for attenuating age-related eye diseases before they limit sight.