Mutant p53 and Cellular Stress Pathways: A Criminal Alliance That Promotes Cancer Progression

The capability of cancer cells to manage stress induced by hypoxia, nutrient shortage, acidosis, redox imbalance, loss of calcium homeostasis and exposure to drugs is a key factor to ensure cancer survival and chemoresistance. Among the protective mechanisms utilized by cancer cells to cope with stress a pivotal role is played by the activation of heat shock proteins (HSP) response, anti-oxidant response induced by nuclear factor erythroid 2-related factor 2 (NRF2), the hypoxia-inducible factor-1 (HIF-1), the unfolded protein response (UPR) and autophagy, cellular processes strictly interconnected. However, depending on the type, intensity or duration of cellular stress, the balance between pro-survival and pro-death pathways may change, and cell survival may be shifted into cell death. Mutations of p53 (mutp53), occurring in more than 50% of human cancers, may confer oncogenic gain-of-function (GOF) to the protein, mainly due to its stabilization and interaction with the above reported cellular pathways that help cancer cells to adapt to stress. This review will focus on the interplay of mutp53 with HSPs, NRF2, UPR, and autophagy and discuss how the manipulation of these interconnected processes may tip the balance towards cell death or survival, particularly in response to therapies.

Immunogenicity profiling of protein antigens from capsular group B Neisseria meningitidis

Outer membrane vesicle (OMV)- based vaccines have been used to provide strain-specific protection against capsular group B Neisseria meningitidis infections, but the full breadth of the immune response against the components of the OMV has not been established. Sera from adults vaccinated with an OMV vaccine were used to screen 91 outer membrane proteins (OMPs) incorporated in an antigen microarray panel. Antigen-specific IgG levels were quantified pre-vaccination, and after 12 and 18 weeks. These results were compared with IgG levels from mice vaccinated with the same OMV vaccine. The repertoires of highly responding antigens in humans and mice overlapped, but were not identical. The highest responding antigens to human IgG comprised four integral OMPs (PorA, PorB, OpcA and PilQ), a protein which promotes the stability of PorA and PorB (RmpM) and two lipoproteins (BamC and GNA1162). These observations will assist in evaluating the role of minor antigen components within OMVs in providing protection against meningococcal infection. In addition, the relative dominance of responses to integral OMPs in humans emphasizes the importance of this subclass and points to the value of maintaining conformational epitopes from integral membrane proteins in vaccine formulations.

The emerging importance of noncoding RNAs in the insecticide tolerance, with special emphasis on Plutella xylostella (Lepidoptera: Plutellidae)

Recently generated high-throughput sequencing data sets have shed light on the important regulatory roles of noncoding RNA (ncRNA) molecules in the development of higher organisms. Nowadays it is well-known that regulatory ncRNAs can bind complementary RNA or DNA sequences and recruit chromatin remodelers to selectively modulate gene expression. Consequently, genome sequencing and transcriptomics technologies are now being used to reveal hidden associations among ncRNAs and distinct biological mechanisms. This is the case for the diamondback moth Plutella xylostella, a worldwide pest known to infest cruciferous crops and to display resistance to most insecticides, including Bacillus thuringiensis (Bt) based biopesticides. In P. xylostella, it is thought that ncRNAs could play important roles in both development and insecticide resistance. This review will highlight recent insights into the roles of ncRNAs in P. xylostella and related lepidopterans, and will outline genetic engineering technologies which might be used to design efficient ncRNA-based pest control strategies. This article is categorized under: Regulatory RNAs/RNAi/Riboswitches > Regulatory RNAs.

Effects of Platycodins Folium on Depression in Mice Based on a UPLC-Q/TOF-MS Serum Assay and Hippocampus Metabolomics

Major depressive disorder (MDD), also known as depression, is a state characterized by low mood and aversion to activity. Platycodins Folium (PF) is the dried leaf of Platycodon grandiflorum, with anti-inflammatory and antioxidative activities. Our previous research suggested that PF was rich in flavonoids, phenols, organic acids, triterpenoid saponins, coumarins and terpenoids. This study aimed to investigate the antidepressant effect of PF using lipopolysaccharide (LPS)-induced depressive mice. Several behavior tests (sucrose preference test (SPT), forced swimming test (FST) and tail suspension test (TST)) and biochemical parameters (IL-6, TNF-α and SOD levels) were used to evaluate the antidepressive effect of PF on LPS-induced depression model. Furthermore, a UPLC-Q/TOF-MS-based metabolomics approach was applied to explore the latent mechanism of PF in attenuating depression. As a result, a total of 21 and 11 metabolites that potentially contribute to MDD progress and PF treatment were identified in serum and hippocampus, respectively. The analysis of metabolic pathways revealed that lipid metabolism, amino acid metabolism, energy metabolism, arachidonic acid metabolism, glutathione metabolism and inositol phosphate metabolism were disturbed in a model of mice undergoing MDD and PF treatment. These results help us to understand the pathogenesis of depression in depth, and to discover targets for clinical diagnosis and treatment. They also provide the possibility of developing PF into an anti-depressantive agent.

The interaction of Hemin and Sestrin2 modulates oxidative stress and colon tumor growth

Several large epidemiological and animal studies demonstrate a direct correlation between dietary heme iron intake and/or systemic iron levels and cancer risk in several cancers including colorectal cancer (CRC). However, the precise mechanisms for how heme iron contributes to CRC and how cancer cells respond to heme iron-induced stress are still unclear. Previously we have shown that one of the stress-inducible proteins, Sestrin2 (SESN2), is a novel tumor suppressor in colon by limiting endoplasmic reticulum stress and mammalian target of rapamycin complex 1 (mTORC1) signaling and tumor growth. But the relationship between heme iron and SESN2, especially in the context of colon carcinogenesis, was not investigated previously. Here, we found that hemin dose-dependently increased SESN2 expression in an oxidative stress and nuclear factor (erythroid-derived 2)-like 2 (NFE2L2, NRF2)-dependent manner. Since SESN2 overexpression reduced hemin-induced oxidative stress, SESN2 could be an important target of NRF2 exerting antioxidant function. Indeed, expression of several oxidative stress responsive proteins such as NRF2 and its target genes was reduced by SESN2. Although we formerly reported that SESN2 expression was reduced after p53 mutation in colon tumors, mouse colon tumors, which have intact p53 and NRF2, induced SESN2 expression in response to iron stimulus. Although SESN2 overexpression decreased murine colon tumor cell growth both in vitro and in vivo, it rendered colon cancer cells more resistant to hemin-induced apoptosis and therefore promoted tumor growth during hemin treatment. Taken together, although SESN2 generally suppresses tumorigenesis, it can produce tumor-promoting role in iron-rich environment by suppressing oxidative stress-associated cancer cell death.

Epigenetic mechanisms related to cognitive decline during aging

Cognitive decline is a hallmark of the aging nervous system, characterized by increasing memory loss and a deterioration of mental capacity, which in turn creates a favorable context for the development of neurodegenerative diseases. One of the most detrimental alterations that occur at the molecular level in the brain during aging is the modification of the epigenetic mechanisms that control gene expression. As a result of these epigenetic-driven changes in the transcriptome most of the functions of the brain including synaptic plasticity, learning, and memory decline with aging. The epigenetic mechanisms altered during aging include DNA methylation, histone modifications, nucleosome remodeling, and microRNA-mediated gene regulation. In this review, we examine the current evidence concerning the changes of epigenetic modifications together with the molecular mechanisms underlying impaired neuronal gene transcription during aging. Herein, we discuss the alterations of DNA methylation pattern that occur in old neurons. We will also describe the most prominent age-related histone posttranslational modifications in the brain since changes in acetylation and methylation of specific lysine residues on H3 and H4 are associated to functional decline in the old. In addition, we discuss the role that changes in the levels of certain miRNAs would play in cognitive decline with aging. Finally, we provide an overview about the mechanisms either extrinsic or intrinsic that would trigger epigenetic changes in the aging brain, and the consequences of these changes, i.e., altered transcriptional profile and reactivation of transposable elements in old brain.

Synthetic-Evolution Reveals Narrow Paths to Regulation of the Saccharomyces cerevisiae Mitotic Kinesin-5 Cin8

Cdk1 has been found to phosphorylate the majority of its substrates in disordered regions, but some substrates maintain precise phosphosite positions over billions of years. Here, we examined the phosphoregulation of the kinesin-5, Cin8, using synthetic Cdk1-sites. We first analyzed the three native Cdk1 sites within the catalytic motor domain. Any single site conferred regulation, but to different extents. Synthetic sites were then systematically generated by single amino-acid substitutions, starting from a phosphodeficient variant of Cin8. Out of 29 synthetic Cdk1 sites, 8 disrupted function; 19 were neutral, similar to the phospho-deficient variant; and only two gave rise to phosphorylation-dependent spindle phenotypes. Of these two, one was immediately adjacent to a native Cdk1 site. Only one novel site position resulted in phospho-regulation. This site was sampled elsewhere in evolution, but the synthetic version was inefficient in S. cerevisiae. This study shows that a single phosphorylation site can modulate complex spindle dynamics, but likely requires further evolution to optimally regulate the precise reaction cycle of a mitotic motor.

Nutrigenomics as a tool to study the impact of diet on aging and age-related diseases: the Drosophila approach

Aging is a complex phenomenon caused by the time-dependent loss of cellular homeodynamics and consequently of physiological organismal functions. This process is affected by both genetic and environmental (e.g., diet) factors, as well as by their constant interaction. Consistently, deregulation of nutrient sensing and signaling pathways is considered a hallmark of aging. Nutrigenomics is an emerging scientific discipline that studies changes induced by diet on the genome and thus it considers the intersection of three topics, namely health, diet, and genomics. Model organisms, such as the fruit fly Drosophila melanogaster, have been successfully used for in vivo modeling of higher metazoans aging and for nutrigenomic studies. Drosophila is a well-studied organism with sophisticated genetics and a fully annotated sequenced genome, in which ~ 75% of human disease-related genes have functional orthologs. Also, flies have organs/tissues that perform the equivalent functions of most mammalian organs, while discrete clusters of cells maintain insect carbohydrate homeostasis in a way similar to pancreatic cells. Herein, we discuss the mechanistic connections between nutrition and aging in Drosophila, and how this model organism can be used to study the effect of different diets (including natural products and/or their derivatives) on higher metazoans longevity.

Gene expression of terminal oxidases in two marine bacterial strains exposed to nanomolar oxygen concentrations

The final step of aerobic respiration is carried out by a terminal oxidase transporting electrons to oxygen (O2). Prokaryotes harbor diverse terminal oxidases that differ in phylogenetic origin, structure, biochemical function, and affinity for O2. Here we report on the expression of high-affinity (cytochrome cbb3 oxidase), low-affinity (cytochrome aa3 oxidase), and putative low-affinity (cyanide-insensitive oxidase (CIO)) terminal oxidases in the marine bacteria Idiomarina loihiensis L2-TR and Marinobacter daepoensis SW-156 upon transition to very low O2 concentrations (<200 nM), measured by RT-qPCR. In both strains, high-affinity cytochrome cbb3 oxidase showed the highest expression levels and was significantly up-regulated upon transition to low O2 concentrations. Low-affinity cytochrome aa3 oxidase showed very low transcription levels throughout the incubation. Surprisingly, however, it was also up-regulated upon transition to low O2 concentrations. In contrast, putative low-affinity CIO had much lower expression levels and markedly different regulation patterns between the two strains. These results demonstrate that exposure to low O2 concentrations regulates the gene expression of different types of terminal oxidases, but also that the type and magnitude of transcriptional response is species-dependent. Therefore, in situ transcriptome data cannot, without detailed knowledge of the transcriptional regulation of the species involved, be translated into relative respiratory activity.

PIK3CA mutations in ductal carcinoma in situ and adjacent invasive breast cancer

PIK3CA is one of the most frequently mutated genes in invasive breast cancer (IBC). These mutations are generally associated with hyper-activation of the phosphatidylinositol 3-kinase signaling pathway, which involves increased phosphorylation of AKT (p-AKT). This pathway is negatively regulated by the tumor suppressor PTEN. Data are limited regarding the variant allele frequency (VAF) of PIK3CA, PTEN and p-AKT expression during various stages of breast carcinogenesis. Therefore, the aim of this study was to gain insight into PIK3CA VAF and associated PTEN and p-AKT expression during the progression from ductal carcinoma in situ (DCIS) to IBC. We isolated DNA from DCIS tissue, synchronous IBC and metastasis when present. These samples were pre-screened for PIK3CA hotspot mutations using the SNaPshot assay and, if positive, validated and quantified by digital PCR. PTEN and p-AKT expression was evaluated by immunohistochemistry using the Histo-score (H-score). Differences in PIK3CA VAF, PTEN and p-AKT H-scores between DCIS and IBC were analyzed. PIK3CA mutations were detected in 17 out of 73 DCIS samples, 16 out of 73 IBC samples and 3 out of 23 lymph node metastasis. We detected a significantly higher VAF of PIK3CA in the DCIS component compared to the adjacent IBC component (P = 0.007). The expression of PTEN was significantly higher in DCIS compared to the IBC component in cases with a wild-type (WT) PIK3CA status (P = 0.007), while it remained similar in both components when PIK3CA was mutated. There was no difference in p-AKT expression between DCIS and the IBC component. In conclusion, our data suggest that PIK3CA mutations could be essential specifically in early stages of breast carcinogenesis. In addition, these mutations do not co-occur with PTEN expression during DCIS progression to IBC in the majority of patients. These results may contribute to further unraveling the process of breast carcinogenesis, and this could aid in the development of patient-specific treatment.

A modular degron library for synthetic circuits in mammalian cells

Tight control over protein degradation is a fundamental requirement for cells to respond rapidly to various stimuli and adapt to a fluctuating environment. Here we develop a versatile, easy-to-handle library of destabilizing tags (degrons) for the precise regulation of protein expression profiles in mammalian cells by modulating target protein half-lives in a predictable manner. Using the well-established tetracycline gene-regulation system as a model, we show that the dynamics of protein expression can be tuned by fusing appropriate degron tags to gene regulators. Next, we apply this degron library to tune a synthetic pulse-generating circuit in mammalian cells. With this toolbox we establish a set of pulse generators with tailored pulse lengths and magnitudes of protein expression. This methodology will prove useful in the functional roles of essential proteins, fine-tuning of gene-expression systems, and enabling a higher complexity in the design of synthetic biological systems in mammalian cells.

Crosstalk between Ras and inositol phosphate signaling revealed by lithium action on inositol monophosphatase in Schizophyllum commune

Mushroom forming basidiomycete Schizophyllum commune has been used as a tractable model organism to study fungal sexual development. Ras signaling activation via G-protein-coupled receptors (GPCRs) has been postulated to play a significant role in the mating and development of S. commune. In this study, a crosstalk between Ras signaling and inositol phosphate signaling by inositol monophosphatase (IMPase) is revealed. Constitutively active Ras1 leads to the repression of IMPase transcription and lithium action on IMPase activity is compensated by the induction of IMPase at transcriptome level. Astonishingly, in S. commune lithium induces a considerable shift to inositol phosphate metabolism leading to a massive increase in the level of higher phosphorylated inositol species up to the inositol pyrophosphates. The lithium induced metabolic changes are not observable in a constitutively active Ras1 mutant. In addition to that, proteome profile helps us to elucidate an overview of lithium action to the broad aspect of fungal metabolism and cellular signaling. Taken together, these findings imply a crosstalk between Ras and inositol phosphate signaling.

Metabolomics Profiling before, during, and after the Beijing Olympics: A Panel Study of Within-Individual Differences during Periods of High and Low Air Pollution

BACKGROUND

The metabolome is a collection of exogenous chemicals and metabolites from cellular processes that may reflect the body's response to environmental exposures. Studies of air pollution and metabolomics are limited.

OBJECTIVES

To explore changes in the human metabolome before, during, and after the 2008 Beijing Olympics Games, when air pollution was high, low, and high, respectively.

METHODS

Serum samples were collected before, during, and after the Olympics from 26 participants in an existing panel study. Gas and ultra-high performance liquid chromatography/mass spectrometry were used in metabolomics analysis. Repeated measures ANOVA, network analysis, and enrichment analysis methods were employed to identify metabolites and classes associated with air pollution changes.

RESULTS

A total of 886 molecules were measured in our metabolomics analysis. Network partitioning identified four modules with 65 known metabolites that significantly changed across the three time points. All known molecules in the first module ([Formula: see text]) were lipids (e.g., eicosapentaenoic acid, stearic acid). The second module consisted primarily of dipeptides ([Formula: see text], e.g., isoleucylglycine) plus 8 metabolites from four other classes (e.g., hypoxanthine, 12-hydroxyeicosatetraenoic acid). Most of the metabolites in Modules 3 (19 of 23) and 4 (5 of 5) were unknown. Enrichment analysis of module-identified metabolites indicted significantly overrepresented pathways, including long- and medium-chain fatty acids, polyunsaturated fatty acids (n3 and n6), eicosanoids, lysolipid, dipeptides, fatty acid metabolism, and purine metabolism [(hypo) xanthine/inosine-containing pathways].

CONCLUSIONS

We identified two major metabolic signatures: one consisting of lipids, and a second that included dipeptides, polyunsaturated fatty acids, taurine, and xanthine. Metabolites in both groups decreased during the 2008 Beijing Olympics, when air pollution was low, and increased after the Olympics, when air pollution returned to normal (high) levels. https://doi.org/10.1289/EHP3705.

Apparent synonymous mutation F9 c.87A>G causes secretion failure by in-frame mutation with aberrant splicing

INTRODUCTION

Hemophilia B is an X-linked recessive bleeding disorder caused by coagulation factor IX (FIX) gene (F9) mutations. Several F9 synonymous mutations have been known to cause hemophilia B; however, the deleterious mechanisms underlying the development of hemophilia B have not been completely understood. To elucidate the molecular pathogenesis causing hemophilia B, we investigated the synonymous F9 mutation: c.87A>G, p.(Thr29=).

MATERIALS AND METHODS

The influence of F9 c.87A>G on mRNA splicing was analyzed by exon-trap assay and in silico prediction. We prepared FIX expression vectors using mutant F9 cDNA and transfected HepG2 cells to investigate intracellular transport and extracellular secretion of FIX. Intracellular kinetics of the expressed FIX was examined by treatment with the proteasome inhibitor MG132.

RESULTS

Exon-trap analysis revealed that F9 c.87A>G resulted in almost (99.1%) aberrant splicing (r.83_88del). In silico analysis predicted that F9 c.87A>G influenced the splicing pattern by generating an available aberrant 5' splice site. The aberrant F9 mRNA (r.83_88del) was translated to a mutant FIX p.Cys28_Val30delinsPhe with an in-frame mutation at the signal peptide cleavage site. Simultaneously, a small amount (0.9%) of mutant F9 r.87A>G translating into WT FIX p.Thr29 = was also observed. The mutant FIX was abnormally retained in the endoplasmic reticulum (ER) and was not extracellularly secreted. It appeared to be intracellularly degraded via proteasome-dependent degradation machinery.

CONCLUSION

F9 c.87A>G was found to cause abnormal mRNA splicing, r.83_88del, and produce the mutant FIX p.Cys28_Val30delinsPhe. The mutant FIX is an abnormal protein with extracellular secretory defects and is intracellularly eliminated via proteasome-dependent ER-associated degradation.

Ultrastructural patterns of photoacclimation and photodamage to photosynthetic algae cell under environmental stress

In oxygenic phototrophs including unicellular algae, acclimation to and damage by diverse environmental stresses induce profound changes in the ultrastructural organization of the cell. These alterations reflect acclimation of the photosynthetic apparatus to unfavorable conditions (mainly reduction of the chloroplast and its membranal system) and rewiring of the photo-fixed carbon fluxes in the cell. These changes, eventually pursuing mitigation of the photooxidative damage risk, are manifested by the formation of diverse carbon-rich inclusions. Although the physiological and molecular basis of these processes are well understood, the ultrastructural manifestations of the stress responses are often fragmented and frequently controversial. This minireview attempts to generalize on the ultrastructural patterns accompanying stresses in the photosynthetic cell, involving the concerted rearrangements of its assimilatory and storage compartments. The changes characteristic of normal functioning and emergency reduction of the chloroplast thylakoids under harsh stress are also addressed. Special attention is paid to the manifestations of the engagement of photoprotection via active (energy-dependent non-photochemical quenching) and passive mechanisms (e.g. optical shielding by secondary carotenoids). We also underline the potentially important role of autophagy-like processes and provide a more integral view of ultrastructural rearrangements under stress.

Differential expression of secreted factors SOSTDC1 and ADAMTS8 cause profibrotic changes in linear morphoea fibroblasts

BACKGROUND

Linear morphoea (LM) is a rare connective tissue disorder characterized by a line of thickened skin and subcutaneous tissue and can also affect the underlying muscle and bone. Little is known about the disease aetiology, with treatment currently limited to immune suppression, and disease recurrence post-treatment is common.

OBJECTIVES

In order to uncover new therapeutic avenues, the cell-intrinsic changes in LM fibroblasts compared with site-matched controls were characterized.

METHODS

We grew fibroblasts from site-matched affected and unaffected regions from five patients with LM, we subjected them to gene expression analysis and investigation of SMAD signalling.

RESULTS

Fibroblasts from LM lesions showed increased migration, proliferation, altered collagen processing, and abnormally high basal levels of phosphorylated SMAD2, thereby rendering them less responsive to transforming growth factor (TGF)-β1 and reducing the degree of myofibroblast differentiation, which is a key component of the wound-healing and scarring process in normal skin. Conditioned media from normal fibroblasts could reverse LM-affected fibroblast migration and proliferation, suggesting that the LM phenotype is driven by an altered secretome. Gene array analysis and RNA-Seq indicated upregulation of ADAMTS8 and downregulation of FRAS1 and SOSTDC1. SOSTDC1 knock-down recapitulated the reduced TGF-β1 responsiveness and LM fibroblast migration, while overexpression of ADAMTS8 induced myofibroblast markers.

CONCLUSIONS

We demonstrate that cell-intrinsic changes in the LM fibroblast secretome lead to changes observed in the disease, and that secretome modulation could be a viable therapeutic approach in the treatment of LM.

Access to a high resource environment protects against accelerated maturation following early life stress: A translational animal model of high, medium and low security settings

Early life exposure to a low security setting, characterized by a scarcity of resources and limited food access, increases the risk for psychiatric illness and metabolic dysfunction. We utilized a translational rat model to mimic a low security environment and determined how this manipulation affected offspring behavior, metabolism, and puberty. Because food insecurity in humans is associated with reduced access to healthy food options the "low security" rat manipulation combined a Western diet with exposure to a limited bedding and nesting manipulation (WD-LB). In this setting, dams were provided with limited nesting materials during the pups' early life (P2-P10). This manipulation was contrasted with standard rodent caging (SD) and environmental enrichment (EE), to model "medium security" and "high security" environments, respectively. To determine if transitioning from a low to high security environment improved outcomes, some juvenile WD-LB offspring were exposed to EE. Maternal care was impacted by these environments such that EE dams engaged in high quality care when on the nest, but spent less time on the nest than SD dams. Although WD-LB dams excessively chased their tails, they were very attentive to their pups, perhaps to compensate for limited resources. Offspring exposed to WD-LB only displayed subtle changes in behavior. However, WD-LB exposure resulted in significant metabolic dysfunction characterized by increased body weight, precocious puberty and alterations in the hypothalamic kisspeptin system. These negative effects of WD-LB on puberty and weight regulation were mitigated by EE exposure. Collectively, these studies suggest that both compensatory maternal care and juvenile enrichment can reduce the impact of a low security environment. Moreover, they highlight how utilizing diverse models of resource (in)stability can reveal mechanisms that confer vulnerability and resilience to early life stress.

Uraemic syndrome of chronic kidney disease: altered remote sensing and signalling

Uraemic syndrome (also known as uremic syndrome) in patients with advanced chronic kidney disease involves the accumulation in plasma of small-molecule uraemic solutes and uraemic toxins (also known as uremic toxins), dysfunction of multiple organs and dysbiosis of the gut microbiota. As such, uraemic syndrome can be viewed as a disease of perturbed inter-organ and inter-organism (host-microbiota) communication. Multiple biological pathways are affected, including those controlled by solute carrier (SLC) and ATP-binding cassette (ABC) transporters and drug-metabolizing enzymes, many of which are also involved in drug absorption, distribution, metabolism and elimination (ADME). The remote sensing and signalling hypothesis identifies SLC and ABC transporter-mediated communication between organs and/or between the host and gut microbiota as key to the homeostasis of metabolites, antioxidants, signalling molecules, microbiota-derived products and dietary components in body tissues and fluid compartments. Thus, this hypothesis provides a useful perspective on the pathobiology of uraemic syndrome. Pathways considered central to drug ADME might be particularly important for the body's attempts to restore homeostasis, including the correction of disturbances due to kidney injury and the accumulation of uraemic solutes and toxins. This Review discusses how the remote sensing and signalling hypothesis helps to provide a systems-level understanding of aspects of uraemia that could lead to novel approaches to its treatment.

PPARγ agonists: potential treatment for autism spectrum disorder by inhibiting the canonical WNT/β-catenin pathway

Autism spectrum disorder (ASD) is a neurodevelopmental disorder that is characterized by a deficit in social interactions and communication with repetitive and restrictive behavior. No curative treatments are available for ASD. Pharmacological treatments do not address the core ASD behaviors, but target comorbid symptoms. Dysregulation of the core neurodevelopmental pathways is associated with the clinical presentation of ASD, and the canonical WNT/β-catenin pathway is one of the major pathways involved. The canonical WNT/β-catenin pathway participates in the development of the central nervous system, and its dysregulation involves developmental cognitive disorders. In numerous tissues, the canonical WNT/β-catenin pathway and peroxisome proliferator-activated receptor gamma (PPARγ) act in an opposed manner. In ASD, the canonical WNT/β-catenin pathway is increased while PPARγ seems to be decreased. PPARγ agonists present a beneficial effect in treatment for ASD children through their anti-inflammatory role. Moreover, they induce the inhibition of the canonical WNT/β-catenin pathway in several pathophysiological states. We focus this review on the hypothesis of an opposed interplay between PPARγ and the canonical WNT/β-catenin pathway in ASD and the potential role of PPARγ agonists as treatment for ASD.

Engineered PPR proteins as inducible switches to activate the expression of chloroplast transgenes

The engineering of plant genomes presents exciting opportunities to modify agronomic traits and to produce high-value products in plants. Expression of foreign proteins from transgenes in the chloroplast genome offers advantages that include the capacity for prodigious protein output, the lack of transgene silencing and the ability to express multicomponent pathways from polycistronic mRNA. However, there remains a need for robust methods to regulate plastid transgene expression. We designed orthogonal activators that boost the expression of chloroplast transgenes harbouring cognate cis-elements. Our system exploits the programmable RNA sequence specificity of pentatricopeptide repeat proteins and their native functions as activators of chloroplast gene expression. When expressed from nuclear transgenes, the engineered proteins stimulate the expression of plastid transgenes by up to ~40-fold, with maximal protein abundance approaching that of Rubisco. This strategy provides a means to regulate and optimize the expression of foreign genes in chloroplasts and to avoid deleterious effects of their products on plant growth.

Cancer-associated mutation and beyond: The emerging biology of isocitrate dehydrogenases in human disease

Isocitrate dehydrogenases (IDHs) are critical metabolic enzymes that catalyze the oxidative decarboxylation of isocitrate to α-ketoglutarate (αKG), NAD(P)H, and CO₂. IDHs epigenetically control gene expression through effects on αKG-dependent dioxygenases, maintain redox balance and promote anaplerosis by providing cells with NADPH and precursor substrates for macromolecular synthesis, and regulate respiration and energy production through generation of NADH. Cancer-associated mutations in IDH1 and IDH2 represent one of the most comprehensively studied mechanisms of IDH pathogenic effect. Mutant enzymes produce (R)-2-hydroxyglutarate, which in turn inhibits αKG-dependent dioxygenase function, resulting in a global hypermethylation phenotype, increased tumor cell multipotency, and malignancy. Recent studies identified wild-type IDHs as critical regulators of normal organ physiology and, when transcriptionally induced or down-regulated, as contributing to cancer and neurodegeneration, respectively. We describe how mutant and wild-type enzymes contribute on molecular levels to disease pathogenesis, and discuss efforts to pharmacologically target IDH-controlled metabolic rewiring.

Highly efficient therapeutic gene editing of human hematopoietic stem cells

Re-expression of the paralogous γ-globin genes (HBG1/2) could be a universal strategy to ameliorate the severe β-globin disorders sickle cell disease (SCD) and β-thalassemia by induction of fetal hemoglobin (HbF, α2γ2)1. Previously, we and others have shown that core sequences at the BCL11A erythroid enhancer are required for repression of HbF in adult-stage erythroid cells but are dispensable in non-erythroid cells2-6. CRISPR-Cas9-mediated gene modification has demonstrated variable efficiency, specificity, and persistence in hematopoietic stem cells (HSCs). Here, we demonstrate that Cas9:sgRNA ribonucleoprotein (RNP)-mediated cleavage within a GATA1 binding site at the +58 BCL11A erythroid enhancer results in highly penetrant disruption of this motif, reduction of BCL11A expression, and induction of fetal γ-globin. We optimize conditions for selection-free on-target editing in patient-derived HSCs as a nearly complete reaction lacking detectable genotoxicity or deleterious impact on stem cell function. HSCs preferentially undergo non-homologous compared with microhomology-mediated end joining repair. Erythroid progeny of edited engrafting SCD HSCs express therapeutic levels of HbF and resist sickling, while those from patients with β-thalassemia show restored globin chain balance. Non-homologous end joining repair-based BCL11A enhancer editing approaching complete allelic disruption in HSCs is a practicable therapeutic strategy to produce durable HbF induction.

Restoration of myocardial glucose uptake with facilitated myocardial glucose transporter 4 translocation contributes to alleviation of diabetic cardiomyopathy in rats after duodenal-jejunal bypass

AIMS/INTRODUCTION

Duodenal-jejunal bypass (DJB) surgery has been reported to effectively relieve diabetic cardiomyopathy (DCM). However, the specific mechanisms remain largely unknown. The present study was designed to determine the alterations of myocardial glucose uptake (MGU) after DJB and their effects on DCM.

MATERIALS AND METHODS

Duodenal-jejunal bypass and sham surgeries were carried out in diabetic rats induced by a high-fat diet and a low dose of streptozotocin, with chow-diet fed rats as controls. Bodyweight, food intake, glucose homeostasis and lipid profiles were measured at indicated time-points. Cardiac function was evaluated by transthoracic echocardiography and hemodynamic measurement. Cardiac remodeling was assessed by a series of morphometric analyses along with transmission electron microscopy. Positron-emission tomography with fluorine-18 labeled fluorodeoxyglucose was carried out to evaluate the MGU in vivo. Furthermore, myocardial glucose transporters (GLUT; GLUT1 and GLUT4), myocardial insulin signaling and GLUT-4 translocation-related proteins were investigated to elucidate the underlying mechanisms.

RESULTS

The DJB group showed restored systolic and diastolic cardiac function, along with significant remission in cardiac hypertrophy, cardiac fibrosis, lipid deposit and ultrastructural disorder independent of weight loss compared with the sham group. Furthermore, the DJB group showed upregulated myocardial insulin signaling, hyperphosphorylation of AKT substrate of 160 kDa (AS160) and TBC1D1, along with preserved soluble N-ethylmaleimide-sensitive factor attachment protein receptor proteins, facilitating the GLUT-4 translocation to the myocardial cell surface and restoration of MGU.

CONCLUSIONS

The present findings provide evidence that restoration of MGU is implicated in the alleviation of DCM after DJB through facilitating GLUT-4 translocation, suggesting a potential choice for treatment of human DCM if properly implemented.

Blocking tombusvirus replication through the antiviral functions of DDX17-like RH30 DEAD-box helicase

Positive-stranded RNA viruses replicate inside cells and depend on many co-opted cellular factors to complete their infection cycles. To combat viruses, the hosts use conserved restriction factors, such as DEAD-box RNA helicases, which can function as viral RNA sensors or as effectors by blocking RNA virus replication. In this paper, we have established that the plant DDX17-like RH30 DEAD-box helicase conducts strong inhibitory function on tombusvirus replication when expressed in plants and yeast surrogate host. The helicase function of RH30 was required for restriction of tomato bushy stunt virus (TBSV) replication. Knock-down of RH30 levels in Nicotiana benthamiana led to increased TBSV accumulation and RH30 knockout lines of Arabidopsis supported higher level accumulation of turnip crinkle virus. We show that RH30 DEAD-box helicase interacts with p33 and p92pol replication proteins of TBSV, which facilitates targeting of RH30 from the nucleus to the large TBSV replication compartment consisting of aggregated peroxisomes. Enrichment of RH30 in the nucleus via fusion with a nuclear retention signal at the expense of the cytosolic pool of RH30 prevented the re-localization of RH30 into the replication compartment and canceled out the antiviral effect of RH30. In vitro replicase reconstitution assay was used to demonstrate that RH30 helicase blocks the assembly of viral replicase complex, the activation of the RNA-dependent RNA polymerase function of p92pol and binding of p33 replication protein to critical cis-acting element in the TBSV RNA. Altogether, these results firmly establish that the plant DDX17-like RH30 DEAD-box helicase is a potent, effector-type, restriction factor of tombusviruses and related viruses. The discovery of the antiviral role of RH30 DEAD-box helicase illustrates the likely ancient roles of RNA helicases in plant innate immunity.

Biased signaling agonist of dopamine D3 receptor induces receptor internalization independent of β-arrestin recruitment

Agonist-induced internalization of G protein-coupled receptors (GPCRs) is a significant step in receptor kinetics and is known to be involved in receptor down-regulation. However, the dopamine D3 receptor (D3R) has been an exception wherein agonist induces D3Rs to undergo desensitization followed by pharmacological sequestration - which is defined as the sequestration of cell surface receptors into a more hydrophobic fraction within the plasma membrane without undergoing the process of receptor internalization. Pharmacological sequestration renders the receptor in an inactive state on the membrane. In our previous study we demonstrated that a novel class of D3R agonists exemplified by SK608 have biased signaling properties via the G-protein dependent pathway and do not induce D3R desensitization. In this study, using radioligand binding assay, immunoblot or immunocytochemistry methods, we observed that SK608 induced internalization of human D3R stably expressed in CHO, HEK and SH-SY5Y cells which are derived from neuroblastoma cells, suggesting that it is not a cell-type specific event. Further, we have evaluated the potential mechanism of D3R internalization induced by these biased signaling agonists. SK608-induced D3R internalization was time- and concentration-dependent. In comparison, dopamine induced D3R upregulation and pharmacological sequestration in the same assays. GRK2 and clathrin/dynamin I/II are the key molecular players in the SK608-induced D3R internalization process, while β-arrestin 1/2 and GRK-interacting protein 1(GIT1) are not involved. These results suggest that SK608-promoted D3R internalization is similar to the type II internalization observed among peptide binding GPCRs.

Inhibiting bacterial secretion systems in the fight against antibiotic resistance

Antimicrobial resistance is a mounting global health crisis that threatens a resurgence of life-threatening bacterial infections. Despite intensive drug discovery efforts, the rate of antimicrobial resistance outpaces the discovery of new antibiotic agents. One of the major mechanisms driving the rapid propagation of antibiotic resistance is bacterial conjugation mediated by the versatile type IV secretion system (T4SS). The search for therapeutic compounds that prevent the spread of antibiotic resistance via T4SS-dependent mechanisms has identified several promising molecular scaffolds that disrupt resistance determinant dissemination. In this brief review, we highlight the progress and potential of conjugation inhibitors and anti-virulence compounds that target diverse T4SS machineries. These studies provide a solid foundation for the future development of potent, dual-purpose molecular scaffolds that can be used as biochemical tools to probe type IV secretion mechanisms and target bacterial conjugation in clinical settings to prevent the dissemination of antibiotic resistance throughout microbial populations.

Arabidopsis FLL2 promotes liquid-liquid phase separation of polyadenylation complexes

An important component of cellular biochemistry is the concentration of proteins and nucleic acids in non-membranous compartments^1,2. These biomolecular condensates are formed from processes that include liquid-liquid phase separation. The multivalent interactions necessary for liquid-liquid phase separation have been extensively studied in vitro^1,3. However, the regulation of this process in vivo is poorly understood. Here we identify an in vivo regulator of liquid-liquid phase separation through a genetic screen targeting factors required for Arabidopsis RNA-binding protein FCA function. FCA contains prion-like domains that phase-separate in vitro, and exhibits behaviour in vivo that is consistent with phase separation. The mutant screen identified a functional requirement for FLL2, a coiled-coil protein, in the formation of FCA nuclear bodies. FCA reduces transcriptional read-through by promoting proximal polyadenylation at many sites in the Arabidopsis genome^3,4. FLL2 was required to promote this proximal polyadenylation, but not the binding of FCA to target RNA. Ectopic expression of FLL2 increased the size and number of FCA nuclear bodies. Crosslinking with formaldehyde captured in vivo interactions between FLL2, FCA and the polymerase and nuclease modules of the RNA 3'-end processing machinery. These 3' RNA-processing components colocalized with FCA in the nuclear bodies in vivo, which indicates that FCA nuclear bodies compartmentalize 3'-end processing factors to enhance polyadenylation at specific sites. Our findings show that coiled-coil proteins can promote liquid-liquid phase separation, which expands our understanding of the principles that govern the in vivo dynamics of liquid-like bodies.

Role of Ca2+ as protectant under heat stress by regulation of photosynthesis and membrane saturation in Anabaena PCC 7120

The present study was aimed at understanding the effects of heat stress on selected physiological and biochemical parameters of a model cyanobacterium, Anabaena PCC 7120 in addition to amelioration strategy using exogenous Ca²⁺. A comparison of the cells exposed to heat stress (0-24 h) in the presence or absence of Ca²⁺ clearly showed reduction in colony-forming ability and increase in reactive oxygen species (ROS) leading to loss in the viability of cells of Ca²⁺-deficient cultures. There was higher level of saturation in membrane lipids of the cells supplemented with Ca²⁺ along with higher accumulation of proline. Similarly, higher quantum yield (7.8-fold) in Ca²⁺-supplemented cultures indicated role of Ca²⁺ in regulation of photosynthesis. Relative electron transport rate (rETR) decreased in both the sets with the difference in the rate of decrease (slow) in Ca²⁺-supplemented cultures. The Ca²⁺-supplemented sets also maintained high levels of open reaction centers of PS II in comparison to Ca²⁺-deprived cells. Increase in transcripts of both subunits ((rbcL and rbcS) of RubisCO from Ca²⁺-supplemented Anabaena cultures pointed out the role of Ca²⁺ in sustenance of photosynthesis of cells via CO₂ fixation, thus, playing an important role in maintaining metabolic status of the heat-stressed cyanobacterium.

RNAi-knockdown of the Locusta migratoria nuclear export factor protein results in insect mortality and alterations in gut microbiome

BACKGROUND

The migratory locust Locusta migratoria is one of the most important agricultural pests worldwide. The nuclear export factor 1 (NXF1) protein plays a crucial role in mediating mRNA transport from the nucleus to the cytoplasm. This study evaluates whether NXF1 could be a potential target for RNAi-mediated pest control of L. migratoria.

RESULTS

We cloned and characterized the nuclear export factor lm-nxf1 of L. migratoria. Lm-nxf1 was expressed in all tissues examined, including head, fat body, hemolymph, trunk, leg and midgut, with high expression observed in the hemolymph and fat body. Injection of lm-nxf1 dsRNA into hemolymph resulted in inhibition of mRNA export in hemocytes, which were used as a target for observing mRNA export. Total hemocyte levels were reduced by ca. 97% in lm-nxf1-dsRNA-treated locusts, and high insect mortality occurred with LT₅₀ = 7.75 day as compared with 18.15 day for gfp-dsRNA-treated controls. Further, the locust intestine became atrophy, and the opportunistic pathogens Enterobacter aerogenes, Klebsiella pneumoniae and Enterobacter asburiae were specifically detected in midgut after lm-nxf1 dsRNA treatment.

CONCLUSIONS

The results reveal that knockdown of the lm-nxf1 gene affects the survival of L. migratoria, indicating that lm-nxf1 is a potential target for RNAi-mediated pest control. © 2018 Society of Chemical Industry.

Mitochondrial complex II of plants: subunit composition, assembly, and function in respiration and signaling

Complex II [succinate dehydrogenase (succinate-ubiquinone oxidoreductase); EC 1.3.5.1; SDH] is the only enzyme shared by both the electron transport chain and the tricarboxylic acid (TCA) cycle in mitochondria. Complex II in plants is considered unusual because of its accessory subunits (SDH5-SDH8), in addition to the catalytic subunits of SDH found in all eukaryotes (SDH1-SDH4). Here, we review compositional and phylogenetic analysis and biochemical dissection studies to both clarify the presence and propose a role for these subunits. We also consider the wider functional and phylogenetic evidence for SDH assembly factors and the reports from plants on the control of SDH1 flavination and SDH1-SDH2 interaction. Plant complex II has been shown to influence stomatal opening, the plant defense response and reactive oxygen species-dependent stress responses. Signaling molecules such as salicyclic acid (SA) and nitric oxide (NO) are also reported to interact with the ubiquinone (UQ) binding site of SDH, influencing signaling transduction in plants. Future directions for SDH research in plants and the specific roles of its different subunits and assembly factors are suggested, including the potential for reverse electron transport to explain the succinate-dependent production of reactive oxygen species in plants and new avenues to explore the evolution of plant mitochondrial complex II and its utility.

Hepatotoxicity of Telfaria occidentalis root extracts on wistar albino rat

The present study investigates the toxicity of Telfaria occidentalis root extracted with different solvents. This was with a view to validating its widely acclaimed use as poison in traditional parlance. Air-dried powdered root of Telfaria occidentalis was extracted separately with distilled water, methanol and diethyl ether. Twenty albino rats were randomly placed into four groups of five animals per group: Group I served as the positive control and were administered distilled water only while groups II, III and IV animals were administered 50 mg/kg body weight of aqueous, methanolic and diethyl ether extracts respectively for two weeks. Activities of aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), superoxide dismutase and catalase were assayed in the liver homogenate and serum. Levels of total cholesterol, HDL-cholesterol, LDL-cholesterol as well as lipid peroxidation were also measured in the liver and serum of animals. Results showed that the level of AST, ALT, ALP as well as LDL-cholesterol and HDL-cholesterol in the serum of group IV animals increased significantly relative to the control group. Antioxidant enzyme biomarkers such as catalase and superoxide dismutase as well as lipid peroxidation were significantly increased in the serum of group IV animals relative to the control. The study concluded that toxicity of root extract of Telfaria occidentalis is solvent-dependent.

Plant defense factors involved in Olea europaea resistance against Xylella fastidiosa infection

Olive quick decline syndrome (OQDS) is a dangerous plant disease, caused by the bacterium Xylella fastidiosa, which targets olive (Olea europaea). Since field observations suggested that some olive cultivars (i.e. Leccino) were more resistant to OQDS than others (i.e. Cellina di Nardò), the plant defense strategies adopted by olive to contrast X. fastidiosa infection were investigated. In the present study, ELISA and genetic approaches were used to confirm plant infection, while microbial colonization mechanism and distribution in host plant tissues and reactive oxygen species (ROS) levels were examined by light, scanning electron and confocal microscopy analyses. Spectrophotometric and chromatographic techniques were performed to measure secondary metabolites content and qPCR assay was carried out for monitoring plant gene expression variation. Our analysis showed that X. fastidiosa caused accumulation of ROS in Leccino samples compared to Cellina di Nardò. Moreover, the infection induced the up-regulation of defense-related genes, such as NADPH oxidase, some protein kinases, pathogen plant response factors and metabolic enzymes. We also found that Leccino plants enhanced the production of specific antioxidant and antimicrobial molecules, to fight the pathogen and avoid its spreading into xylem vessels. We provided new information on OQDS resistance mechanism applied by Leccino cultivar. In particular, we evidenced that high concentrations of ROS, switching on plant defence signalling pathways, may represent a key factor in fighting X. fastidiosa infection.

Increased fes1a thermotolerance is induced by BAG6 knockout

KEY MESSAGE: (1) The fes1a bag6 double mutant shows an increased short term thermotolerance compared to fes1a. BAG6 is a suppressor of Fes1A; (2) IQ motif is essential to effective performance of BAG6. (3) Calmodulin was involved in signal transduction. (4) BAG6 is localized in the nucleus. HSP70s play an important role in the heat-induced stress tolerance of plants. However, effective HSP70 function requires the assistance of many co-chaperones. BAG6 and Fes1A are HSP70-binding proteins that are critical for Arabidopsis thaliana thermotolerance. Despite this importance, little is known about how these co-chaperones interact. In this study, we assessed the thermotolerance of a fes1a bag6 double mutant. We found that the fes1a bag6 double mutant shows an increased short-term thermotolerance compared to fes1a. However, calmodulin inhibitors diminished this enhanced thermotolerance in the fes1a bag6 double mutant. In addition, we found the IQ motif to be essential for effective BAG6 performance. Since BAG6 is localized in the nucleus, the signal transduction is likely to involve nuclear calcium signaling.

Responses of olive plants exposed to different irrigation treatments in combination with heat shock: physiological and molecular mechanisms during exposure and recovery

A water-deficit period, leading to stomatal control and overexpression of protective proteins (sHSP and DHN), contributes to olive´s tolerance to later imposed stress episodes. Aquaporins modulation is important in olive recovery. Olive is traditionally cultivated in dry farming or in high water demanding irrigated orchards. The impact of climate change on these orchards remains to unveil, as heat and drought episodes are increasing in the Mediterranean region. To understand how young plants face such stress episodes, olive plants growing in pots were exposed to well-irrigated and non-irrigated treatments. Subsequently, plants from each treatment were either exposed to 40 °C for 2 h or remained under control temperature. After treatments, all plants were allowed to grow under well-irrigated conditions (recovery). Leaves were compared for photosynthesis, relative water content, mineral status, pigments, carbohydrates, cell membrane permeability, lipid peroxidation and expression of the protective proteins' dehydrin (OeDHN1), heat-shock proteins (OeHSP18.3), and aquaporins (OePIP1.1 and OePIP2.1). Non-irrigation, whilst increasing carbohydrates, reduced some photosynthetic parameters to values below the ones of the well-irrigated plants. However, when both groups of plants were exposed to heat, well-irrigated plants suffered more drastic decreases of net CO₂ assimilation rate and chlorophyll b than non-irrigated plants. Overall, OeDHN1 and OeHSP18.3 expression, which was increased in non-irrigated treatment, was potentiated by heat, possibly to counteract the increase of lipid peroxidation and loss of membrane integrity. Plants recovered similarly from both irrigation and temperature treatments, and recovery was associated with increased aquaporin expression in plants exposed to one type of stress (drought or heat). These data represent an important contribution for further understanding how dry-farming olive will cope with drought and heat episodes.

Lysosomal Dysfunction in Down Syndrome Is APP-Dependent and Mediated by APP-βCTF (C99)

Lysosomal failure underlies pathogenesis of numerous congenital neurodegenerative disorders and is an early and progressive feature of Alzheimer's disease (AD) pathogenesis. Here, we report that lysosomal dysfunction in Down ayndrome (trisomy 21), a neurodevelopmental disorder and form of early onset AD, requires the extra gene copy of amyloid precursor protein (APP) and is specifically mediated by the β cleaved carboxy terminal fragment of APP (APP-βCTF, C99). In primary fibroblasts from individuals with DS, lysosomal degradation of autophagic and endocytic substrates is selectively impaired, causing them to accumulate in enlarged autolysosomes/lysosomes. Direct measurements of lysosomal pH uncovered a significant elevation (0.6 units) as a basis for slowed LC3 turnover and the inactivation of cathepsin D and other lysosomal hydrolases known to be unstable or less active when lysosomal pH is persistently elevated. Normalizing lysosome pH by delivering acidic nanoparticles to lysosomes ameliorated lysosomal deficits, whereas RNA sequencing analysis excluded a transcriptional contribution to hydrolase declines. Cortical neurons cultured from the Ts2 mouse model of DS exhibited lysosomal deficits similar to those in DS cells. Lowering APP expression with siRNA or BACE1 inhibition reversed cathepsin deficits in both fibroblasts and neurons. Deleting one Bace1 allele from adult Ts2 mice had similar rescue effects in vivo The modest elevation of endogenous APP-βCTF needed to disrupt lysosomal function in DS is relevant to sporadic AD where APP-βCTF, but not APP, is also elevated. Our results extend evidence that impaired lysosomal acidification drives progressive lysosomal failure in multiple forms of AD.SIGNIFICANCE STATEMENT Down syndrome (trisomy 21) (DS) is a neurodevelopmental disorder invariably leading to early-onset Alzheimer's disease (AD). We showed in cells from DS individuals and neurons of DS models that one extra copy of a normal amyloid precursor protein (APP) gene impairs lysosomal acidification, thereby depressing lysosomal hydrolytic activities and turnover of autophagic and endocytic substrates, processes vital to neuronal survival. These deficits, which were reversible by correcting lysosomal pH, are mediated by elevated levels of endogenous β-cleaved carboxy-terminal fragment of APP (APP-βCTF). Notably, similar endosomal-lysosomal pathobiology emerges early in sporadic AD, where neuronal APP-βCTF is also elevated, underscoring its importance as a therapeutic target and underscoring the functional and pathogenic interrelationships between the endosomal-lysosomal pathway and genes causing AD.

Vibrio Flagellar Synthesis

Vibrio spp. are highly motile Gram-negative bacteria, ubiquitously found in aquatic environments. Some Vibrios are responsible for disease and morbidity of marine invertebrates and humans, while others are studied for their symbiotic interactions. Vibrio spp. are motile due to synthesis of flagella that rotate and propel the bacteria. Many Vibrio spp. synthesize monotrichous polar flagella (e.g., V. cholerae, V. alginolyticus); however, some synthesize peritrichous or lophotrichous flagella. Flagellar-mediated motility is intimately connected to biological and cellular processes such as chemotaxis, biofilm formation, colonization, and virulence of Vibrio spp. This review focuses on the polar flagellum and its regulation in regard to Vibrio virulence and environmental persistence.

Cytosine methylation of mitochondrial DNA at CpG sequences impacts transcription factor A DNA binding and transcription

In eukaryotes, cytosine methylation of nuclear DNA at CpG sequences (5mCpG) regulates epigenetic inheritance through alterations in chromatin structure. However, mitochondria lack nucleosomal chromatin, therefore the molecular mechanisms by which 5mCpG influences mitochondria must be different and are as yet unknown. Mitochondrial Transcription Factor A (TFAM) is both the primary DNA-compacting protein in the mitochondrial DNA (mtDNA) nucleoid and a transcription-initiation factor. TFAM must encounter hundreds of CpGs in mtDNA, so the occurrence of 5mCpG has the potential to impact TFAM-DNA recognition. We used biophysical approaches to determine whether 5mCpG alters any TFAM-dependent activities. 5mCpG in the heavy strand promoter (HSP1) increased the binding affinity of TFAM and induced TFAM multimerization with increased cooperativity compared to nonmethylated DNA. However, 5mCpG had no apparent effect on TFAM-dependent DNA compaction. Additionally, 5mCpG had a clear and context-dependent effect on transcription initiating from the three mitochondrial promoters. Taken together, our findings demonstrate that 5mCpG in the mitochondrial promoter region does impact TFAM-dependent activities in vitro.

Understanding the influence of carbon nanomaterials on microbial communities

Carbon nanomaterials (CNMs) are widely used because of their unique advantages in recent years. At the same time, the influence of CNMs on the environment is becoming increasingly prominent. This review mainly introduces the research progress in the effects of fullerenes, multi-walled carbon nanotubes (MWCNTs), single-walled carbon nanotubes (SWCNTs) and graphene on microorganisms and their toxicity mechanisms. On this basis, we have analyzed beneficial and adverse effects of fullerenes, graphene, MWCNTs and SWCNTs to microorganisms, and discussed the similarities of the toxicity mechanisms of different CNMs on microorganisms. This review helps provide ideas on how to protect microorganisms from the impacts of carbon nanomaterials, and it will be conductive to providing a strong theoretical basis for better application of carbon nanomaterials.

Identification of NPAC as a novel biomarker and regulator for hepatocellular carcinoma

OBJECTIVE

Hepatocellular carcinoma (HCC) has a high morbidity and mortality around the world, yet the effective therapeutic option for HCC is still limited. NPAC, also known as glyoxylate reductase 1 homolog, is a new nuclear protein recently implicated in tumor biology. However, the role of NPAC in HCC remains unclear. The present study aimed to evaluate the clinical significance and potential role of NPAC in HCC.

METHODS

The NPAC expression in HCC tissues and matched adjacent normal tissues was detected by real-time polymerase chain reaction, immunohistochemistry (IHC), and Western blot analysis. The clinical significance of the expression of NPAC in HCC was assessed by the Kaplan-Meier survival curve and the Cox regression model. In addition, we established a doxiline-induced overexpression of the NPAC system. The effects of NPAC on HCC cell proliferation, migration, and apoptosis were checked by CCK-8 proliferation assays, transwell, and flow cytometry, respectively.

RESULTS

The NPAC expression was significantly downregulated in HCC tissues and HCC cell lines. NPAC reduction was significantly correlated with poorer survival among patients with HCC, and the multivariate analysis confirmed its independent prognostic value. Furthermore, overexpression of NPAC dramatically suppressed the proliferation of HCC cells and promoted HCC cells apoptosis. Besides, the levels of phosphorylation of janus kinase 2 (JAK2) and signal transduction and activator 3 (STAT3) were significantly reduced after overexpression of NPAC in HCC cell lines.

CONCLUSIONS

These results suggest that NPAC may play an important role in the development and progression of HCC, and can act as a novel potential prognostic biomarker and therapeutic target for HCC.

Battle of the sexes: contrasting roles of testis-specific protein Y-encoded (TSPY) and TSPX in human oncogenesis

The Y-located testis-specific protein Y-encoded (TSPY) and its X-homologue TSPX originated from the same ancestral gene, but act as a proto-oncogene and a tumor suppressor gene, respectively. TSPY has specialized in male-specific functions, while TSPX has assumed the functions of the ancestral gene. Both TSPY and TSPX harbor a conserved SET/NAP domain, but are divergent at flanking structures. Specifically, TSPX contains a C-terminal acidic domain, absent in TSPY. They possess contrasting properties, in which TSPY and TSPX, respectively, accelerate and arrest cell proliferation, stimulate and inhibit cyclin B-CDK1 phosphorylation activities, have no effect and promote proteosomal degradation of the viral HBx oncoprotein, and exacerbate and repress androgen receptor (AR) and constitutively active AR variant, such as AR-V7, gene transactivation. The inhibitory domain has been mapped to the carboxyl acidic domain in TSPX, truncation of which results in an abbreviated TSPX exerting positive actions as TSPY. Transposition of the acidic domain to the C-terminus of TSPY results in an inhibitory protein as intact TSPX. Hence, genomic mutations/aberrant splicing events could generate TSPX proteins with truncated acidic domain and oncogenic properties as those for TSPY. Further, TSPY is upregulated by AR and AR-V7 in ligand-dependent and ligand-independent manners, respectively, suggesting the existence of a positive feedback loop between a Y-located proto-oncogene and male sex hormone/receptors, thereby amplifying the respective male oncogenic actions in human cancers and diseases. TSPX counteracts such positive feedback loop. Hence, TSPY and TSPX are homologues on the sex chromosomes that function at the two extremes of the human oncogenic spectrum.

Cypate and Cypate-Glucosamine as Near-Infrared Fluorescent Probes for In Vivo Tumor Imaging

Near-infrared (NIR) imaging is a promising technique for use as a noninvasive and sensitive diagnostic tool. Although the NIR fluorescently labeled glucose analog glucosamine (cypate-glucosamine) has applications in preclinical imaging, the transport pathways and fate of this probe in tissues remain unaddressed. Here, we have synthesized and characterized cypate and cypate-glucosamine conjugate (cy-2-glu), and investigated the probable transport pathways of these probes in vitro and in vivo. We compared uptake of the probes in the presence and absence of excess d-glucose, "saturated cypate" and palmitic acid in two normal-cancer cell line pairs: lung cancer (A549)-normal (MRC9) and prostate cancer (DU145)-normal (BPH). Breast cancer (MDA-MB-231) and liver cancer (HepG2) cell lines were also examined. Results support use of the glucose transport pathway by cy-2-glu and fatty acid transport pathway by cypate. Mass spectrometry data on the in vitro extracts revealed deamidation of cy-2-glu in prostate and liver cells, suggesting release of glucosamine. In vivo biodistribution studies in mice engrafted with breast tumors showed a distinct accumulation of cy-2-glu in liver and tumors, and to a lesser extent in kidneys and spleen. A negligible accumulation of cypate alone in tumors was observed. Analysis of urine extracts revealed renal excretion of the cy-2-glu probe in the form of free cypate, indicating deamidation of cy-2-glu in tissues. Thus, investigation of the metabolic pathways used by NIR probes such as cy-2-glu advances their use in the detection and monitoring of tumor progression in preclinical animal studies.

Micromanaging aerobic respiration and glycolysis in cancer cells

BACKGROUND

Cancer cells possess a common metabolic phenotype, rewiring their metabolic pathways from mitochondrial oxidative phosphorylation to aerobic glycolysis and anabolic circuits, to support the energetic and biosynthetic requirements of continuous proliferation and migration. While, over the past decade, molecular and cellular studies have clearly highlighted the association of oncogenes and tumor suppressors with cancer-associated glycolysis, more recent attention has focused on the role of microRNAs (miRNAs) in mediating this metabolic shift. Accumulating studies have connected aberrant expression of miRNAs with direct and indirect regulation of aerobic glycolysis and associated pathways.

SCOPE OF REVIEW

This review discusses the underlying mechanisms of metabolic reprogramming in cancer cells and provides arguments that the earlier paradigm of cancer glycolysis needs to be updated to a broader concept, which involves interconnecting biological pathways that include miRNA-mediated regulation of metabolism. For these reasons and in light of recent knowledge, we illustrate the relationships between metabolic pathways in cancer cells. We further summarize our current understanding of the interplay between miRNAs and these metabolic pathways. This review aims to highlight important metabolism-associated molecular components in the hunt for selective preventive and therapeutic treatments.

MAJOR CONCLUSIONS

Metabolism in cancer cells is influenced by driver mutations but is also regulated by posttranscriptional gene silencing. Understanding the nuanced regulation of gene expression in these cells and distinguishing rapid cellular responses from chronic adaptive mechanisms provides a basis for rational drug design and novel therapeutic strategies.