Quality Control Components Research Articles

Targeting Hsp70 facilitated protein quality control for treatment of polyglutamine diseases.

The polyglutamine (polyQ) diseases are a group of nine fatal, adult-onset neurodegenerative disorders characterized by the misfolding and aggregation of mutant proteins containing toxic expansions of CAG/polyQ tracts. The heat shock protein 90 and 70 (Hsp90/Hsp70) chaperone machinery is a key component of cellular protein quality control, playing a role in the regulation of folding, aggregation, and degradation of polyQ proteins. The ability of Hsp70 to facilitate disaggregation and degradation of misfolded proteins makes it an attractive therapeutic target in polyQ diseases. Genetic studies have demonstrated that manipulation of Hsp70 and related co-chaperones can enhance the disaggregation and/or degradation of misfolded proteins in models of polyQ disease. Therefore, the development of small molecules that enhance Hsp70 activity is of great interest. However, it is still unclear if currently available Hsp70 modulators can selectively enhance disaggregation or degradation of misfolded proteins without perturbing other Hsp70 functions essential for cellular homeostasis. This review discusses the multifaceted role of Hsp70 in protein quality control and the opportunities and challenges Hsp70 poses as a potential therapeutic target in polyQ disease.

Manipulation of Plastidial Protein Quality Control Components as a New Strategy to Improve Carotenoid Contents in Tomato Fruit.

Carotenoids such as β-carotene (pro-vitamin A) and lycopene accumulate at high levels during tomato (Solanum lycopersicum L.) fruit ripening, contributing to the characteristic color and nutritional quality of ripe tomatoes. Besides their role as pigments in chromoplast-harboring tissues such as ripe fruits, carotenoids are important for photosynthesis and photoprotection in the chloroplasts of photosynthetic tissues. Interestingly, recent work in Arabidopsis thaliana (L.) Heynh. has unveiled a critical role of chloroplast protein quality control components in the regulation of carotenoid biosynthesis. The accumulation (i.e. degradation rate) and activity (i.e. folding status) of phytoene synthase (PSY) and other Arabidopsis biosynthetic enzymes is modulated by chaperones such as Orange (OR) and Hsp70 in coordination with the stromal Clp protease complex. OR and Clp protease were recently shown to also influence PSY stability and carotenoid accumulation in tomato. Here we show how manipulating the levels of plastid-localized Hsp70 in transgenic tomato plants can also impact the accumulation of carotenoids in ripe fruit. The resulting carotenoid profile and chromoplast ultrastructure, however, are different from those obtained in tomatoes from transgenic lines with increased OR activity. These results suggest that different chaperone families target different processes related to carotenoid metabolism and accumulation during tomato ripening. We further discuss other possible targets for future manipulation in tomato based on the knowledge acquired in Arabidopsis.

Proteasome dysfunction in alveolar type 2 epithelial cells is associated with acute respiratory distress syndrome

Proteasomes are a critical component of quality control that regulate turnover of short-lived, unfolded, and misfolded proteins. Proteasome activity has been therapeutically targeted and considered as a treatment option for several chronic lung disorders including pulmonary fibrosis. Although pharmacologic inhibition of proteasome activity effectively prevents the transformation of fibroblasts to myofibroblasts, the effect on alveolar type 2 (AT2) epithelial cells is not clear. To address this knowledge gap, we generated a genetic model in which a proteasome subunit, RPT3, which promotes assembly of active 26S proteasome, was conditionally deleted in AT2 cells of mice. Partial deletion of RPT3 resulted in 26S proteasome dysfunction, leading to augmented cell stress and cell death. Acute loss of AT2 cells resulted in depletion of alveolar surfactant, disruption of the alveolar epithelial barrier and, ultimately, lethal acute respiratory distress syndrome (ARDS). This study underscores importance of proteasome function in maintenance of AT2 cell homeostasis and supports the need to further investigate the role of proteasome dysfunction in ARDS pathogenesis.

Identification of ubiquitin-proteasome system components affecting the degradation of the transcription factor Pap1

Signaling cascades respond to specific inputs, but also require active interventions to be maintained in their basal/inactive levels in the absence of the activating signal(s). In a screen to search for protein quality control components required for wild-type tolerance to oxidative stress in fission yeast, we have isolated eight gene deletions conferring resistance not only to H2O2 but also to caffeine. We show that dual resistance acquisition is totally or partially dependent on the transcription factor Pap1. Some gene products, such as the ribosomal-ubiquitin fusion protein Ubi1, the E2 conjugating enzyme Ubc2 or the E3 ligase Ubr1, participate in basal ubiquitin labeling of Pap1, and others, such as Rpt4, are non-essential constituents of the proteasome. We demonstrate here that basal nucleo-cytoplasmic shuttling of Pap1, occurring even in the absence of stress, is sufficient for the interaction of the transcription factor with nuclear Ubr1, and we identify a 30 amino acids peptide in Pap1 as the degron for this important E3 ligase. The isolated gene deletions increase only moderately the concentration of the transcription factor, but it is sufficient to enhance basal tolerance to stress, probably by disturbing the inactive stage of this signaling cascade.

An analytical strategy for accurate, rapid and sensitive quantitative analysis of isoflavones in traditional Chinese medicines using ultra-high performance supercritical fluid chromatography: Take Radix Puerariae as an example

Isoflavones are phenolic phytoestrogens due to their structural similarity to estradiol, so they usually serve as active component for quality control of traditional Chinese medicines (TCMs) rich in isoflavones. However, TCMs contains various kinds of similar isoflavones, especially isomers, which to a significant extent hinders accurate analysis of isoflavones in TCMs. Here, we present a novel analytical strategy for quality control of TCMs rich in isoflavones using ultra-high performance supercritical fluid chromatography coupled to photodiode array detection (UHPSFC–PDA) and tandem mass spectrometry (UHPSFC–MS/MS). Both chromatography and mass spectrometry parameters were optimized in order to develop an accurate, rapid, sensitive method for quantification of isoflavones. The reproducibility of quantitative analysis of multi-components by single marker (QAMS) using UHPSFC–PDA was discussed in terms of mobile phase gradient, temperature and backpressure for the first time. An analytical method for the analysis of isoflavones using UHPSFC–MS/MS was developed for the first time, and the established method was successfully applied to quantify isoflavones in three species of Radix Puerariae. The study showed Radix Pueraria Peduncularis contained higher amounts of isoflavones than Radix Puerariae Thomsonii, and it is worth noting that Radix Pueraria Peduncularis was often overlooked by researchers. It took less than 8 min with the current method and the limit of detection was not more than 0.05 ng/ml, which was definitely sufficient for anlysis of various samples from TCMs without enrichment.

Solution structure and backbone dynamics for S1 domain of ribosomal protein S1 from Mycobacterium tuberculosis.

The pro-drug pyrazinamide is hydrolyzed to pyrazinoic acid (POA) in its use for the treatment of tuberculosis. As a molecule with bactericidal activity, POA binds to the C-terminal S1 domain of ribosomal protein S1 from Mycobacterium tuberculosis (MtRpsACTD_S1) to inhibit trans-translation. Trans-translation is a critical component of protein synthesis quality control, and is mediated by transfer-messenger RNA. Here, we have determined the solution structure of MtRpsACTD_S1(280-368), and analyzed its structural dynamics by NMR spectroscopy. The solution structure of MtRpsACTD_S1(280-368) mainly consists of five anti-parallel β strands, two α helices, and two 310 helices. Backbone dynamics reveals that the overall structure of MtRpsACTD_S1(280-368) is rigid, but segment L326-V333 undergoes large amplitude fluctuations on picosecond to nanosecond time scales. In addition, residues V321, H322, V331 and D335 with large Rex values exhibit significant chemical or conformational exchange on microsecond to millisecond time scale. Titration of the truncated MtRpsACTD_S1(280-368) with POA shows similar characteristics to titration of MtRpsACTD_S1(280-438) with POA. In addition, diverse length fragments of MtRpsACTD_S1 show various HN resonance signals, and we find that the interaction of MtRpsA(369-481) with MtRpsACTD_S1(280-368) [Kd = (4.25 ± 0.15) mM] is responsible for the structural difference between MtRpsACTD_S1(280-368) and MtRpsACTD_S1. This work may shed light on the underlying molecular mechanism of MtRpsACTD recognizing and binding POA or mRNA, as well as the detailed mechanism of interactions between MtRpsACTD_S1(280-368) and the additional C-terminal MtRpsA(369-481).

2197-P: SEL1L-HRD1 Endoplasmic Reticulum-Associated Degradation Is Required for Maintaining Glucagon Production in Pancreatic Alpha Cells

Endoplasmic reticulum-associated degradation (ERAD) is a key component of cellular protein quality control, an essential process for pancreatic islet endocrine cells, which synthesize peptide prohormones in high quantities. Two highly conserved ER membrane proteins comprise the core ERAD machinery: HRD1, a ubiquitin ligase that retrotranslocates and ubiquitinates misfolded proteins for proteasomal degradation, and SEL1L, an adaptor protein that identifies ERAD target proteins and is required for HRD1 stability and function. Pancreatic alpha cells, intestinal L-cells, and certain neurons synthesize and differentially cleave proglucagon into tissue-specific hormones, including glucagon and glucagon-like peptide 1 (GLP-1). To investigate the role of ERAD in these cells, we targeted SEL1L deletion with the Cre-lox system, using mice expressing Cre recombinase under the proglucagon promoter. We found that Sel1LGcg mice showed normal growth and glucose homeostasis in vivo. Oral glucose tolerance was equally impaired by administration of the GLP-1 receptor antagonist exendin 9-39 in both Sel1LGcg and control mice, suggesting intact GLP-1 signaling in Sel1LGcg mice. Glucagon secretion in vivo was not significantly different following a 24 hour fast or insulin-induced hypoglycemia. Interestingly, pancreatic glucagon content was reduced by half in Sel1LGcg mice, despite unchanged pancreatic weight. By immunofluorescence, pancreatic islet morphology in Sel1LGcg mice was normal, though α-cells demonstrated increased expression of the ER chaperone BiP and ERAD-associated proteins OS9 and XTP3-B. By transmission electron microscopy, a large subset of α-cells showed significant ER dilation and fewer, smaller glucagon granules. Our data demonstrate that SEL1L-HRD1 ERAD is required for maintaining normal glucagon expression and ER morphology in pancreatic α-cells but does not entirely disrupt proglucagon signaling in vivo. Disclosure R.B. Reinert: None. N. Shrestha: None. Y. Ji: None. L. Qi: None. Funding National Institutes of Health (5T32DK007245)

Perturbation of mRNP biogenesis reveals a dynamic landscape of the Rrp6-dependent surveillance machinery trafficking along the yeast genome

ABSTRACTEukaryotic cells have evolved a nuclear quality control (QC) system to monitor the co-transcriptional mRNA processing and packaging reactions that lead to the formation of export-competent ribonucleoprotein particles (mRNPs). Aberrant mRNPs that fail to pass the QC steps are retained in the nucleus and eliminated by the exonuclease activity of Rrp6. It is still unclear how the surveillance system is precisely coordinated both physically and functionally with the transcription machinery to detect the faulty events that may arise at each step of transcript elongation and mRNP formation. To dissect the QC mechanism, we previously implemented a powerful assay based on global perturbation of mRNP biogenesis in yeast by the bacterial Rho helicase. By monitoring model genes, we have shown that the QC process is coordinated by Nrd1, a component of the NNS complex (Nrd1-Nab3-Sen1) involved in termination, processing and decay of ncRNAs which is recruited by the CTD of RNAP II. Here, we have extended our investigations by analyzing the QC behaviour over the whole yeast genome. We performed high-throughput RNA sequencing (RNA-seq) to survey a large collection of mRNPs whose biogenesis is affected by Rho action and which can be rescued upon Rrp6 depletion. This genome-wide perspective was extended by generating high-resolution binding landscapes (ChIP-seq) of QC components along the yeast chromosomes before and after perturbation of mRNP biogenesis. Our results show that perturbation of mRNP biogenesis redistributes the QC components over the genome with a significant hijacking of Nrd1 and Nab3 from genomic loci producing ncRNAs to Rho-affected protein-coding genes, triggering termination and processing defects of ncRNAs.

Mallostery: Ligand‐dependent Misfolding as a Strategy for Protein Regulation

Protein quality control is an essential set of processes that allow cells to detect, manage, and destroy misfolded and otherwise aberrant proteins. A substantial component of protein quality control involves the selective destruction of misfolded proteins by the ubiquitin proteasome system. Despite the broad range of substrates subject to quality control destruction, these pathways nevertheless show striking specificity for misfolded versions of otherwise stable proteins. This high selectivity can be exploited to regulate the levels of normal proteins through ligand‐mediated, reversible misfolding. This misfolding appears to be a variant of allosteric control that, instead of causing a change in enzyme function, causes a change in enzyme folding to allow recognition and destruction on a contingency basis. This talk will describe an example of such regulated misfolding involved in the control of the sterol synthesizing mevalonate pathway in yeast.HMG‐CoA Reductase (HMGR) is a rate limiting enzyme of the sterol pathway that undergoes regulated degradation as a mechanism of feedback regulation. In yeast, degradation of the HMGR isozyme Hmg2 is keyed to levels of the 20‐carbon isoprenoid geranylgeranyl pyrophosphate (GGPP). When GGPP levels are high, Hmg2 is efficiently degraded by the HRD pathway, which is a major and highly conserved pathway of quality control in the ER known as ER‐associated degradation (ERAD).We have shown that GGPP causes reversible misfolding of Hmg2 that promotes HRD dependent degradation. GGPP‐regulated Hmg2 misfolding shows remarkable similarities to allosteric regulation. GGPP action on Hmg2 is reversible and highly potent, occurring in the mid‐nanomolar range. GGPP's effects are highly specific for its structure, and its effects on Hmg2 can be antagonized both in vivo and in vitro by a related molecule. These features point to a high potency, ligand‐mediated effect on Hmg2 structure. Consistent with this, Hmg2 exists as a multimer, and unregulated Hmg2 variants show classic “toxic subunit” behavior on the regulation of wild‐type Hmg2. Finally, these effects are antagonized by chemical chaperones, demonstrating that the transition caused by GGPP is consistent with misfolding. Accordingly we call this type of regulation “mallostery” to include the ideas of misfolding and allostery in a single term.When viewed through the lens of mallostery, it appears that a number of highly diverse regulatory situations employ similar molecular tactics. Although the generality remains to be discovered, the broadest possibility is for the design of “mallosteric drugs” that specifically program the destruction of desired targets for clinical or basic scientific benefit.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

THE STRUCTURE OF ASSERTIVENESS FROM THE POSITION OF THE CONTINUAL AND HIERARCHICAL APPROACH

This articlе deals with a differential and psychological analysis of assertiveness, which is considered as a systemic multileveled personality trait and is studied from the perspective of the continual and hierarchical approach.The article presents the results of the theoretical analysis of the concept of «assertiveness», outlines the main approaches to understanding the structure of assertiveness in psychological science, the theoretical model of assertiveness from the position of the continual-hierarchical approach. Assertiveness is seen as a complex property of the individual. The phenomenon of «assertiveness» is interpreted as a multilevel, holistic formation, which includes formal-dynamic, content-personal and social-imperative levels. At each level, the assertiveness is represented by certain components that have a specific content. These components interact with each other, complement each other and form an integral property that is not limited to the sum of its constituents and can be considered as a system property characterized by activity and integrity.The article reveals and describes the formal and dynamic (demand for assertiveness, driveness in the manifestation of assertiveness, intensity, easiness, breadth, persistency of assertiveness manifestation, the degree of involvedness or distancing in the process of interaction) and quality (emotional, cognitive, behavioral, control and regulative) components of assertiveness.

Isopsoralen induces different subchronic toxicities and metabolomic outcomes between male and female Wistar rats

Isopsoralen is a major active and quality-control component of Fructus Psoraleae, but lacks a full safety evaluation. We evaluated the oral toxicity of isopsoralen in Wistar rats treated for 3 months at doses of 0, 3.5, 7.0, and 14 mg/kg. Additionally, the plasma metabolomics of isopsoralen in male and female rats treated for 3 months at doses of 0 and 14 mg/kg were investigated by gas chromatography-mass spectrometry. Many abnormalities were observed in the isopsoralen-treated rats, including suppression of body weight gain, and changes in serum biochemical parameters and visceral coefficients. Histopathological changes in liver, pancreatic, and reproductive system tissues were also observed in the isopsoralen-treated rats. The metabolomic analyses showed alterations in many metabolites (19 in female rats; 28 in male rats) after isopsoralen administration. The significant changes in these metabolites revealed metabolomic alterations in the isopsoralen-treated rats, especially in amino acid metabolism regardless of sex, including phenylalanine, tyrosine, and tryptophan biosynthesis and glycine, serine, and threonine metabolism. Furthermore, fatty acid metabolism comprised the main affected pathways in female rats, while lipid metabolism and energy metabolism were the main affected pathways in male rats.

Alice Overwatch: Online Monitoring and Data Quality Assurance Using Hlt Data

ALICE Overwatch is a project started in late 2015 to provide augmented online monitoring and data quality assurance utilizing time-stamped QA histograms produced by the ALICE High Level Trigger. The system receives the data via ZeroMQ, stores it for later review, enriches it with detector specific functionality, and visualizes it via a web application. These provided capabilities are complementary to the existing Data Quality Monitoring system. In addition to basic visualization, additional processing options are accessible to the user, including requests for data within a particular time range or reprocessing of a particular run with different processing parameters. For example, the first ten minutes of a particular run could be investigated for a transient hot trigger channel.Due to similarities between the Overwatch architecture and that which will be used for Quality Control (QC) in LHC Run 3 and beyond, Overwatch will also be utilized to develop and test various QC components during LHC Run 2. Some of the areas of QC development include a new trending and alarm framework. We report on the project᠙s design, development, and status.

A Multi-Center Assessment of Thyroid Function Test Precision in Chemiluminescence Immunoassay (CLIA) Systems

Background: Chemiluminiscence immunoassay (CLIA) is exclusively pragmatic technology for the analysis of biomarker for diagnosis of thyroid disorders. However, performance characteristics of different chemiluminescence immunoassay (CLIA) systems supplied by different manufacturers in diverse set up for thyroid function test (TFT) has not yet been studied well.
 Objective: Our aim is to evaluate laboratory results by assessment of the reproducibility and repeatability of TFTs in three different diagnostic set up to assure the quality of thyroid hormone assay using chemiluminescence immunoassay (CLIA) instruments: Advia Centaur CP (Siemens), Access 2 (Beckman Coulter) and Liaison (Diasorin).
 Materials and Methods: Among the adult male and female individuals visited for thyroid hormone assay, 51 normal individuals were selected for the study. Three aliquots of serum samples were distributed to assess the reproducibility of three different CLIA equipments operated in three diagnostic centers. Additional three aliquots of serum were analyzed weekly for TFT (fFT3, fFT4 and TSH) to check the repeatability of assay in ADVIA Centaur CP set up. Assay precision was determined by reproducibility and repeatability of test results.
 Results: Results of TFTs of serum samples obtained from three different interlaboratory assays using different CLIA systems have achieved good precision showing minimal variance (P>0.05) and acceptable reproducibility. Results are also precise with adequate repeatability showing minimal variance (P >0.05) obtained from the three different intra-laboratory assays in a single CLIA system using ADVIA Centaur CP by same team.
 Conclusion: Our study elucidates the thyroid hormone assay performance of CLIA systems in three centers, which has shown assay precision with good reproducibility and repeatability of thyroid hormone assay. Thus, the analysis of precision as an essential component of quality control is necessary to deliver precise diagnostic services.

Model transfer across additive manufacturing processes via mean effect equivalence of lurking variables

Shape deviation models constitute an important component in quality control for additive manufacturing (AM) systems. However, specified models have a limited scope of application across the vast spectrum of processes in a system that are characterized by different settings of process variables, including lurking variables. We develop a new effect equivalence framework and Bayesian method that enables deviation model transfer across processes in an AM system with limited experimental runs. Model transfer is performed via inference on the equivalent effects of lurking variables in terms of an observed factor whose effect has been modeled under a previously learned process. Studies on stereolithography illustrate the ability of our framework to broaden both the scope of deviation models and the comprehensive understanding of AM systems.

Molecular Regulation of Catalpol and Acteoside Accumulation in Radial Striation and non-Radial Striation of Rehmannia glutinosa Tuberous Root.

Rehmannia glutinosa L., a perennial plant of Scrophulariaceae, is one of the most commonly used herbs in traditional Chinese medicine (TCM) that have been widely cultivated in China. However, to date, the biosynthetic pathway of its two quality-control components, catalpol and acteoside, are only partially elucidated and the mechanism for their tissue-specific accumulation remains unknown. To facilitate the basic understanding of the key genes and transcriptional regulators involved in the biosynthesis of catalpol and acteoside, transcriptome sequencing of radial striation (RS) and non-radial striation (nRS) from four R. glutinosa cultivars was performed. A total of 715,158,202 (~107.27 Gb) high quality reads obtained using paired-end Illumina sequencing were de novo assembled into 150,405 transcripts. Functional annotation with multiple public databases identified 155 and 223 unigenes involved in catalpol and acteoside biosynthesis, together with 325 UGTs, and important transcription factor (TF) families. Comparative analysis of the transcriptomes identified 362 unigenes, found to be differentially expressed in all RS vs. nRS comparisons, with 143 upregulated unigenes, including those encoding enzymes of the catalpol and acteoside biosynthetic pathway, such as geranyl diphosphate synthase (RgGPPS), geraniol 8-hydroxylase (RgG10H), and phenylalanine ammonia-lyase (RgPAL). Other differentially expressed unigenes predicted to be related to catalpol and acteoside biosynthesis fall into UDP-dependent glycosyltransferases (UGTs), as well as transcription factors. In addition, 16 differentially expressed genes were selectively confirmed by real-time PCR. In conclusion, a large unigene dataset of R. glutinosa generated in the current study will serve as a resource for the identification of potential candidate genes for investigation of the tuberous root development and biosynthesis of active components.

Mitochondrial Division Inhibitor 1 Prevents Early-Stage Induction of Mitophagy and Accelerated Cell Death in a Rat Model of Moderate Controlled Cortical Impact Brain Injury

Increasing evidence has implicated dysfunctional mitochondria in the pathophysiology of neurodegenerative disorders. Selective degradation of dysfunctional mitochondria has been termed mitophagy and constitutes a pivotal component of mitochondrial quality control to maintain cellular homeostasis. Mitochondrial fission plays a prominent role in controlling mitochondrial shape and function. However, it is unclear whether mitochondrial fission in the context of eliminating damaged mitochondria is involved in traumatic brain injury (TBI). We examined the role of mitochondrial division inhibitor 1 (Mdivi1), a small-molecule inhibitor of dynamin-related protein (Drp1), in general autophagy and mitophagy after controlled cortical impact (CCI). Mitophagy and the role of Drp1 in this process after CCI were examined using Western blotting, electron microscopy, double immunofluorescence staining, neurological severity scores, and hematoxylin and eosin staining. Statistical analysis was performed using 1-way analysis of variance, followed by the least significant difference test or the Games-Howell test. The rats exposed to CCI exhibited induction of mitophagy and fragmentation of mitochondria. When fission was blocked with Mdivi1, the mitochondria became excessively long and interconnected. Inhibition of Drp1 blocked the induction of mitophagy specifically, which aggravated neurological manifestations and neuronal apoptosis. Mdivi1 activated caspase-3 and caspase-9, implying that selective degradation of damaged mitochondria by autophagy markedly decreased cell apoptosis induced by TBI and, thus, promoted cell survival. The findings from the present study support the hypothesis that Drp1-dependent mitochondrial fission contributes to mitophagy in TBI, and further understanding of the regulatory mechanisms of Drp1 will provide opportunities to develop novel strategies against TBI.

Mitochondrial quality control in cardiac cells: Mechanisms and role in cardiac cell injury and disease.

Mitochondria play an important role in maintaining cardiac homeostasis by supplying the major energy required for cardiac excitation-contraction coupling as well as controlling the key intracellular survival and death pathways. Healthy mitochondria generate ATP molecules through an aerobic process known as oxidative phosphorylation (OXPHOS). Mitochondrial injury during myocardial infarction (MI) impairs OXPHOS and results in the excessive production of reactive oxygen species (ROS), bioenergetic insufficiency, and contributes to the development of cardiovascular diseases. Therefore, mitochondrial biogenesis along with proper mitochondrial quality control machinery, which removes unhealthy mitochondria is pivotal for mitochondrial homeostasis and cardiac health. Upon damage to the mitochondrial network, mitochondrial quality control components are recruited to segregate the unhealthy mitochondria and target aberrant mitochondrial proteins for degradation and elimination. Impairment of mitochondrial quality control and accumulation of abnormal mitochondria have been reported in the pathogenesis of various cardiac disorders and heart failure. Here, we provide an overview of the recent studies describing various mechanistic pathways underlying mitochondrial homeostasis with the main focus on cardiac cells. In addition, this review demonstrates the potential effects of mitochondrial quality control dysregulation in the development of cardiovascular disease.

Protein aggregates encode epigenetic memory of stressful encounters in individual Escherichia coli cells.

Protein misfolding and aggregation are typically perceived as inevitable and detrimental processes tied to a stress- or age-associated decline in cellular proteostasis. A careful reassessment of this paradigm in the E. coli model bacterium revealed that the emergence of intracellular protein aggregates (PAs) was not related to cellular aging but closely linked to sublethal proteotoxic stresses such as exposure to heat, peroxide, and the antibiotic streptomycin. After removal of the proteotoxic stress and resumption of cellular proliferation, the polarly deposited PA was subjected to limited disaggregation and therefore became asymmetrically inherited for a large number of generations. Many generations after the original PA-inducing stress, the cells inheriting this ancestral PA displayed a significantly increased heat resistance compared to their isogenic, PA-free siblings. This PA-mediated inheritance of heat resistance could be reproduced with a conditionally expressed, intracellular PA consisting of an inert, aggregation-prone mutant protein, validating the role of PAs in increasing resistance and indicating that the resistance-conferring mechanism does not depend on the origin of the PA. Moreover, PAs were found to confer robustness to other proteotoxic stresses, as imposed by reactive oxygen species or streptomycin exposure, suggesting a broad protective effect. Our findings therefore reveal the potential of intracellular PAs to serve as long-term epigenetically inheritable and functional memory elements, physically referring to a previous cellular insult that occurred many generations ago and meanwhile improving robustness to a subsequent proteotoxic stress. The latter is presumably accomplished through the PA-mediated asymmetric inheritance of protein quality control components leading to their specific enrichment in PA-bearing cells.

Emerging Cancer Therapeutic Targets in Protein Homeostasis.

Genomic aberrations inside malignant cells through copy number alterations, aneuploidy, and mutations can exacerbate misfolded and unfolded protein burden resulting in increased proteotoxic stress. Increased proteotoxic stress can be deleterious to malignant cells; therefore, these cells rely heavily on the protein quality control mechanisms for survival and proliferation. Components of the protein quality control, such as the unfolded protein response, heat shock proteins, autophagy, and the ubiquitin proteasome system, orchestrate a cascade of downstream events that allow the mitigation of the proteotoxic stress. This dependency makes components of the protein quality control mechanisms attractive targets in cancer therapeutics. In this review, we explore the components of the protein homeostasis especially focusing on the emerging cancer therapeutic agents/targets that are being actively pursued actively.

Variation of main components according to the number of steaming and drying of Rehmanniae radix preparata.

Contents of compounds in Rehmanniae Radix change depending on the number of steaming and drying and the drying method. In this study, as an impregnation method for dried Rehmanniae Radix, takju impregnation and cheongju impregnation were carried out and steaming and drying were repeated for 9 times. The changes of 5-HMF and catalpol contents were analyzed according to the number of repetition times to investigate which stage of steaming and drying is preferable. Also, total nitrogen, crude fat, ash, and crude fiber were measured to analyze changes in general components. 5-HMF was not detected in dried Rehmanniae Radix. As a result of repetitive steaming and drying, the content of 5-HMF increased only slightly from 1 to 4-times steaming and drying but increased significantly from 5-times. The catalpol in dried Rehmanniae Radix was not detected after 5 times of steaming and drying. Sucrose, maltose, and glucose were included in dried Rehmanniae Radix before steaming and drying. However, after the process in both Takju impregnation and Cheongju impregnation, galactose and fructose tended to decrease after production and sucrose and glucose tended to decrease after the increase. In this study condition, 6-times and more steaming and drying were appropriate process which met the content criteria (not less than 0.1%) of the Korean Pharmacopoeia (8th edition) for 5-HMF, an index component for quality control of Rehmanniae Radix Preparata.