Steps Of Life Cycle Research Articles

Nanodynamo quantifies subcellular RNA dynamics revealing extensive coupling between steps of the RNA life cycle

The coordinated action of transcriptional and post-transcriptional machineries shapes gene expression programs at steady state and determines their concerted response to perturbations. We have developed Nanodynamo, an experimental and computational workflow for quantifying the kinetic rates of nuclear and cytoplasmic steps of the RNA life cycle. Nanodynamo is based on mathematical modelling following sequencing of native RNA from cellular fractions and polysomes. We have applied this workflow to triple-negative breast cancer cells, revealing widespread post-transcriptional RNA processing that is mutually exclusive with its co-transcriptional counterpart. We used Nanodynamo to unravel the coupling between transcription, processing, export, decay and translation machineries. We have identified a number of coupling interactions within and between the nucleus and cytoplasm that largely contribute to coordinating how cells respond to perturbations that affect gene expression programs. Nanodynamo will be instrumental in unravelling the determinants and regulatory processes involved in the coordination of gene expression responses.

Abortive Infection of Animal Cells: What Goes Wrong.

Even if a virus successfully binds to a cell, defects in any of the downstream steps of the viral life cycle can preclude the production of infectious virus particles. Such abortive infections are likely common in nature and can provide fundamental insights into the cell and host tropism of viral pathogens. Research over the past 60 years has revealed an incredible diversity of abortive infections by DNA and RNA viruses in various animal cell types. Here we discuss the general causes of abortive infections and provide specific examples from the literature to illustrate the range of abortive infections that have been reported. We also discuss how abortive infections can have critical roles in shaping host immune responses and in the development of virus-induced cancers. Finally, we describe how abortive infections can be applied to basic and clinical research, underscoring the importance of understanding these fascinating aspects of virus biology.

Bafilomycin A1 Inhibits HIV-1 Infection by Disrupting Lysosomal Cholesterol Transport.

The productive replication of human immunodeficiency virus type 1 (HIV-1) involves intricate interactions between viral proteins and host cell machinery. However, the contributions of the lysosomal pathways for HIV-1 replication are not fully understood. The goal of this study was to determine the impact of lysosome-targeting compounds on HIV-1 replication and identify the cellular changes that are linked to HIV-1 inhibition using cell culture models of HIV-1 infection. Here, we demonstrate that the treatment of cells with various pharmacological agents known to inhibit lysosomal functions interfere with HIV-1 replication. The vacuolar ATPase (V-ATPase) inhibitor bafilomycin A1 exerted a potent inhibition of HIV-1 replication. Bafilomycin A1 inhibition of HIV-1 was independent of coreceptor tropism of HIV-1. Our data suggest that bafilomycin A1 inhibits HIV-1 at the post-integration steps of the virus life cycle, which include viral gene expression, virus assembly, and/or egress. Analysis of the cellular alterations following bafilomycin A1 treatment indicates that bafilomycin A1 causes a disruption in lysosome structure and functions. Treatment of cells with bafilomycin A1 caused an accumulation of unesterified cholesterol in lysosomes along with the expansion of the lysosomal compartments. Interestingly, the overexpression of the lysosomal cholesterol transporter Niemann-Pick type C 1 (NPC1) partially relieved bafilomycin A1 inhibition of HIV-1. Collectively, our data suggest that bafilomycin A1 inhibits HIV-1 replication in part by disrupting the lysosomal cholesterol trafficking pathway.

Adenosine modifications impede SARS-CoV-2 RNA-dependent RNA transcription.

SARS-CoV-2, the causative virus of the COVID-19 pandemic, follows SARS and MERS as recent zoonotic coronaviruses causing severe respiratory illness and death in humans. The recurrent impact of zoonotic coronaviruses demands a better understanding of their fundamental molecular biochemistry. Nucleoside modifications, which modulate many steps of the RNA life cycle, have been found in SARS-CoV-2 RNA, although whether they confer a pro- or antiviral effect is unknown. Regardless, the viral RNA-dependent RNA polymerase will encounter these modifications as it transcribes through the viral genomic RNA. We investigated the functional consequences of nucleoside modification on the pre-steady state kinetics of SARS-CoV-2 RNA-dependent RNA transcription using an in vitro reconstituted transcription system with modified RNA templates. Our findings show that N 6-methyladenosine and 2'-O-methyladenosine modifications slow the rate of viral transcription at magnitudes specific to each modification, which has the potential to impact SARS-CoV-2 genome maintenance.

[Translated article] Pharmaceuticals in the environment: A hospital pharmacy perspective

Drugs do not disappear once they have been excreted. In fact, 992 active principles have already been measured in the different environmental matrices. A recent study led by scientists from the University of York has studied the presence of drugs in the rivers of more than 100 different countries, showing that environmental contamination by pharmaceuticals is a global issue and that, concentrations found are frequently harmful to the environment.In this work, we have tried to briefly expose the problem of environmental contamination with medicines, but above all, we have tried to address the possible solutions, with a perspective from the field of hospital pharmacy. This is a very complex matter (a wicked problem), since it involves multiple stakeholders with different visions and interests regarding medicines. In order to find solutions, we will probably need to act at all steps of the drug's life cycle. Until now, health professionals have been part of the problem. It is time for us to be part of the solution.

El impacto ambiental de los medicamentos: una mirada desde la farmacia hospitalaria

Drugs do not disappear once they have been excreted. In fact, 992 active principles have already been measured in the different environmental matrices. A recent study led by scientists from the University of York has studied the presence of drugs in the rivers of more than 100 different countries, showing that environmental contamination by pharmaceuticals is a global issue and that, concentrations found are frequently harmful to the environment.In this work, we have tried to briefly expose the problem of environmental contamination with medicines, but above all, we have tried to address the possible solutions, with a perspective from the field of hospital pharmacy. This is a very complex matter (a wicked problem), since it involves multiple stakeholders with different visions and interests regarding medicines. In order to find solutions, we will probably need to act at all steps of the drug's life cycle. Until now, health professionals have been part of the problem. It is time for us to be part of the solution.

Induction of the antiviral factors APOBEC3A and RSAD2 upon CCL2 neutralization in primary human macrophages involves NF-κB, JAK/STAT, and gp130 signaling.

The CCL2/CC chemokine receptor 2 axis plays key roles in the pathogenesis of HIV-1 infection. We previously reported that exposure of monocyte-derived macrophages to CCL2 neutralizing antibody (αCCL2 Ab) restricted HIV-1 replication at postentry steps of the viral life cycle. This effect was associated with induction of transcripts coding for innate antiviral proteins, including APOBEC3A and RSAD2. This study aimed at identifying the signaling pathways involved in induction of these factors by CCL2 blocking in monocyte-derived macrophages. Through a combination of pharmacologic inhibition, quantitative reverse transcription polymerase chain reaction, Western blotting, and confocal laser-scanning microscopy, we demonstrated that CCL2 neutralization activates the canonical NF-κB and JAK/STAT pathways, as assessed by time-dependent phosphorylation of IκB, STAT1, and STAT3 and p65 nuclear translocation. Furthermore, pharmacologic inhibition of IκB kinase and JAKs strongly reduced APOBEC3A and RSAD2 transcript accumulation elicited by αCCL2 Ab treatment. Interestingly, exposure of monocyte-derived macrophages to αCCL2 Ab resulted in induction of IL-6 family cytokines, and interference with glycoprotein 130, the common signal-transducing receptor subunit shared by these cytokines, inhibited APOBEC3A and RSAD2 upregulation triggered by CCL2 neutralization. These results provide novel insights into the signal transduction pathways underlying the activation of innate responses triggered by CCL2 neutralization in macrophages. Since this response was found to be associated with protective antiviral effects, the new findings may help design innovative therapeutic approaches targeting CCL2 to strengthen host innate immunity.

Dual function of a highly conserved bacteriophage tail completion protein essential for bacteriophage infectivity

Infection of bacteria by phages is a complex multi-step process that includes specific recognition of the host cell, creation of a temporary breach in the host envelope, and ejection of viral DNA into the bacterial cytoplasm. These steps must be perfectly regulated to ensure efficient infection. Here we report the dual function of the tail completion protein gp16.1 of bacteriophage SPP1. First, gp16.1 has an auxiliary role in assembly of the tail interface that binds to the capsid connector. Second, gp16.1 is necessary to ensure correct routing of phage DNA to the bacterial cytoplasm. Viral particles assembled without gp16.1 are indistinguishable from wild-type virions and eject DNA normally in vitro. However, they release their DNA to the extracellular space upon interaction with the host bacterium. The study shows that a highly conserved tail completion protein has distinct functions at two essential steps of the virus life cycle in long-tailed phages.

Development of the ability of future science teachers to put the environmental component into practice

A shift of the science and technology from eco-unfriendly to nature-friendly is reflected in environmental education, which is aimed at improving of the moral values, consumption structure and relationship between human and nature. The purpose of research is to consider the directions of development of the ability of the students to put the environmental component of education into practice upon learning the teaching of the subjects in the higher education institutions. The author discusses the changes being made in the last update of the chemistry curriculum for the secondary school (2017) in accordance with the conception “New Ukrainian school 2016”, dealing with the requirements for the development of the key subject competencies as well as the new structural element of the program “Through content lines” intended to the implementation of the competency-based approach in teaching chemistry. The author suggests that the deep understanding of these changes by the students, especially in the course of mastering by the students such a core competencies as “Environmental awareness and healthy lifestyle”, “Basic competencies in science and technology” is an essential requirement for development of being able to put the environmental component of education into a future practice, that performs in two ways: project-based learning and competency-based learning with the focus on the green tasks.Project-based learning as an educational approach combines research, creative and problem-solving techniques. It was found that combined use of these methods at the different steps of projects life cycles allows shifting the focus from just reproduction of an array of knowledge by the students to the motivative educational journey, which encourages cognitive interest and promotes thinking of the future teachers.Carrying out the projects on various topics, resolving the competency-targeted tasks, cross-disciplinary approach assumes sequentially structured work of the students on solving some tasks that is generally aimed at development of the students’ ability to put the environmental component of education into future practice.

Structure-Activity Relationship of a Pyrrole Based Series of PfPKG Inhibitors as Anti-Malarials.

Controlling malaria requires new drugs against Plasmodium falciparum. The P. falciparum cGMP-dependent protein kinase (PfPKG) is a validated target whose inhibitors could block multiple steps of the parasite's life cycle. We defined the structure-activity relationship (SAR) of a pyrrole series for PfPKG inhibition. Key pharmacophores were modified to enable full exploration of chemical diversity and to gain knowledge about an ideal core scaffold. In vitro potency against recombinant PfPKG and human PKG were used to determine compound selectivity for the parasite enzyme. P. berghei sporozoites and P. falciparum asexual blood stages were used to assay multistage antiparasitic activity. Cellular specificity of compounds was evaluated using transgenic parasites expressing PfPKG carrying a substituted "gatekeeper" residue. The structure of PfPKG bound to an inhibitor was solved, and modeling using this structure together with computational tools was utilized to understand SAR and establish a rational strategy for subsequent lead optimization.

Tubercidin inhibits PRRSV replication via RIG-I/NF-κB pathways and interrupting viral nsp2 synthesis.

Porcine reproductive and respiratory syndrome (PRRS) is one of the most important swine diseases, which causes huge economic loss worldwide. However, there is no effective therapeutic method for PRRS prevention and control. Here, we found that tubercidin, a naturally extracted adenosine analog, exhibited strong anti-porcine reproductive and respiratory syndrome virus (PRRSV) activity. Mechanically, tubercidin inhibited viral binding, replication, and release. Tubercidin suppressed PRRSV non-structural protein 2 expression, which is important for the formation of replication and transcription complex, leading to the block of viral RNA synthesis and PRRSV replication. Moreover, tubercidin could activate retinoic acid-inducible gene I/nuclear factor kappa-light-chain-enhancer of activated B cell innate immune signaling pathway and increased the expression of interferons and proinflammatory cytokines, which was the other way to inhibit PRRSV replication. Our work evaluated the potential value of tubercidin as an antiviral agent on PRRSV replication and provided a new way to prevent PRRSV replication in vitro.

Naphthalene Diimide-Tetraazacycloalkane Conjugates Are G-Quadruplex-Based HIV-1 Inhibitors with a Dual Mode of Action.

Human immunodeficiency virus 1 (HIV-1) therapeutic regimens consist of three or more drugs targeting different steps of the viral life cycle to limit the emergence of viral resistance. In line with the multitargeting strategy, here we conjugated a naphthalene diimide (NDI) moiety with a tetraazacycloalkane to obtain novel naphthalene diimide (NDI)-tetraazacycloalkane conjugates. The NDI inhibits the HIV-1 promoter activity by binding to LTR G-quadruplexes, and the tetraazacycloalkane mimics AMD3100, which blocks HIV entry into cells by interfering with the CXCR4 coreceptor. We synthesized, purified, and tested the metal-free NDI-tetraazacycloalkane conjugate and the two derived metal-organic complexes (MOCs) that incorporate Cu2+ and Zn2+. The NDI-MOCs showed enhanced binding to LTR G4s as assessed by FRET and CD assays in vitro. They also showed enhanced activity in cells where they dose-dependently reduced LTR promoter activity and inhibited viral entry only of the HIV-1 strain that exploited the CXCR4 coreceptor. The time of addition assay confirmed the dual targeting at the different HIV-1 steps. Our results indicate that the NDI-MOC conjugates can simultaneously inhibit viral entry, by targeting the CXCR4 coreceptor, and LTR promoter activity, by stabilizing the LTR G-quadruplexes. The approach of combining multiple targets in a single compound may streamline treatment regimens and improve the overall patient outcomes.

Biology, ecology, and epidemiology of Alternaria species affecting tomato: ground information for the development of a predictive model.

Among pathogens that affect tomato, Alternaria spp. are important due to their implications in yield losses and the contamination of tomato products by mycotoxins. In this study, a systematic literature review was conducted to retrieve and analyze available data on the Alternaria-tomato pathosystem, with particular attention focused on the main biological processes included in the pathogen life cycle and mycotoxin production. We considered 110 papers (selected from initial 2,138 papers) on five Alternaria species that were historically related or recently identified to cause damage to tomato leafage and fruits. Published mathematical models related to Alternaria diseases in tomato were also screened based on their aim and development methods, highlighting the wide use of empirical approach. Retrieved information was also evaluated for applications in building a mechanistic, weather-driven model that incorporates the key steps of the pathogen life cycle. This systematic review highlights several knowledge gaps, including the effect of wetness on infection and environmental requirements for mycotoxin production, and suggests paths for further research especially for recently isolated species.

3D Cooperative Multiplayer Online Game Design as Introduction to Gobak Sodor Traditional Sports Game : Multimedia Development Life Cycle (MDLC)

This research aims to develop a design for a 3D Cooperative Multiplayer Online Game to introduce the traditional sport of “Gobak Sodor” to students. This research method used research and development based on the Multimedia Development Life Cycle (MDLC) steps consisting of concept, design, material collecting, assembly, and testing. Expert Judgement was required to evaluate and validate the developed design by considering various aspects. The testing conducted by media experts resulted in a score of 83,93%. The result of this study indicated that the proposed design falls into the highly feasible category. The results of this research imply that this media can be used to preserve traditional game culture.

Post-transcriptional mechanisms controlling neurogenesis and direct neuronal reprogramming.

Neurogenesis is a tightly regulated process in time and space both in the developing embryo and in adult neurogenic niches. A drastic change in the transcriptome and proteome of radial glial cells or neural stem cells towards the neuronal state is achieved due to sophisticated mechanisms of epigenetic, transcriptional, and post-transcriptional regulation. Understanding these neurogenic mechanisms is of major importance, not only for shedding light on very complex and crucial developmental processes, but also for the identification of putative reprogramming factors, that harbor hierarchically central regulatory roles in the course of neurogenesis and bare thus the capacity to drive direct reprogramming towards the neuronal fate. The major transcriptional programs that orchestrate the neurogenic process have been the focus of research for many years and key neurogenic transcription factors, as well as repressor complexes, have been identified and employed in direct reprogramming protocols to convert non-neuronal cells, into functional neurons. The post-transcriptional regulation of gene expression during nervous system development has emerged as another important and intricate regulatory layer, strongly contributing to the complexity of the mechanisms controlling neurogenesis and neuronal function. In particular, recent advances are highlighting the importance of specific RNA binding proteins that control major steps of mRNA life cycle during neurogenesis, such as alternative splicing, polyadenylation, stability, and translation. Apart from the RNA binding proteins, microRNAs, a class of small non-coding RNAs that block the translation of their target mRNAs, have also been shown to play crucial roles in all the stages of the neurogenic process, from neural stem/progenitor cell proliferation, neuronal differentiation and migration, to functional maturation. Here, we provide an overview of the most prominent post-transcriptional mechanisms mediated by RNA binding proteins and microRNAs during the neurogenic process, giving particular emphasis on the interplay of specific RNA binding proteins with neurogenic microRNAs. Taking under consideration that the molecular mechanisms of neurogenesis exert high similarity to the ones driving direct neuronal reprogramming, we also discuss the current advances in in vitro and in vivo direct neuronal reprogramming approaches that have employed microRNAs or RNA binding proteins as reprogramming factors, highlighting the so far known mechanisms of their reprogramming action.

SPOP inhibits HBV transcription and replication by ubiquitination and degradation of HNF1α.

Hepatitis B virus (HBV) infection remains a significant public health burden worldwide. The persistence of covalently closed circular DNA (cccDNA) within the nucleus of infected hepatocytes is responsible for the failure of antiviral treatments. The ubiquitin proteasome system (UPS) has emerged as a promising antiviral target, as it can regulate HBV replication by promoting critical protein degradation in steps of viral life cycle. Speckle-type POZ protein (SPOP) is a critical adaptor for Cul3-RBX1 E3 ubiquitin ligase complex, but the effect of SPOP on HBV replication is less known. Here, we identified SPOP as a novel host antiviral factor against HBV infection. SPOP overexpression significantly inhibited the transcriptional activity of HBV cccDNA without affecting cccDNA level in HBV-infected HepG2-NTCP and primary human hepatocyte cells. Mechanism studies showed that SPOP interacted with hepatocyte nuclear factor 1α (HNF1α), and induced HNF1α degradation through host UPS pathway. Moreover, the antiviral role of SPOP was also confirmed in vivo. Together, our findings reveal that SPOP is a novel host factor which inhibits HBV transcription and replication by ubiquitination and degradation of HNF1α, providing a potential therapeutic strategy for the treatment of HBV infection.

Life Cycle Analysis of a Particleboard Based on Cardoon and Starch/Chitosan

This work analyzes the life cycle environmental impacts of producing a particleboard based on cardoon fibers and a starch/chitosan adhesive from a “cradle-to-gate” perspective, considering the following life cycle steps: raw material production, adhesive preparation (component mixing and heating), cardoon fiber preparation (crushing and sieving), adhesive and fiber mixing, hot-pressing and final processing. The functional unit is a particleboard with the dimensions of 220 × 220 × 16 mm3. For the life cycle inventory, experimental data obtained from the production of particleboard on a pilot scale were used. The Aspen Plus V9 software was used to simulate the heating process in the manufacture of the biological adhesive and obtain the data associated with this stage. Portuguese or European conditions were considered for the background processes, using data from the EcoInvent V3.5 LCI database. The environmental impacts were quantified using the RECIPE methodology. To complement the study, the VOCs present in the panel were analyzed using the “active headspace” technique. The results show that for most of the environmental impact categories, energy consumption is dominant, followed by starch and chitosan production. Using fully renewable electricity produced in photovoltaic panels, instead of the Portuguese electricity mix, significantly reduces the impacts in most of the environmental impact categories, for example, the carbon footprint is reduced by 34%. Future studies will analyze how the environmental impacts can be further reduced, and how process scale-up may influence them.

Comprehensive mapping of exon junction complex binding sites reveals universal EJC deposition in Drosophila

BackgroundThe exon junction complex (EJC) is involved in most steps of the mRNA life cycle, ranging from splicing to nonsense-mediated mRNA decay (NMD). It is assembled by the splicing machinery onto mRNA in a sequence-independent manner. A fundamental open question is whether the EJC is deposited onto all exon‒exon junctions or only on a subset of them. Several previous studies have made observations supportive of the latter, yet these have been limited by methodological constraints.ResultsIn this study, we sought to overcome these limitations via the integration of two different approaches for transcriptome-wide mapping of EJCs. Our results revealed that nearly all, if not all, internal exons consistently harbor an EJC in Drosophila, demonstrating that EJC presence is an inherent consequence of the splicing reaction. Furthermore, our study underscores the limitations of eCLIP methods in fully elucidating the landscape of RBP binding sites. Our findings highlight how highly specific (low false positive) methodologies can lead to erroneous interpretations due to partial sensitivity (high false negatives).ConclusionsThis study contributes to our understanding of EJC deposition and its association with pre-mRNA splicing. The universal presence of EJC on internal exons underscores its significance in ensuring proper mRNA processing. Additionally, our observations highlight the need to consider both specificity and sensitivity in RBP mapping methodologies.

Sphingomyelin synthase 1 supports two steps of rubella virus life cycle

Our knowledge of the regulatory mechanisms that govern the replication of the rubella virus (RV) in human cells is limited. To gain insight into the host-pathogen interaction, we conducted a loss-of-function screening using the CRISPR-Cas9 system in the human placenta-derived JAR cells. We identified sphingomyelin synthase 1 (SGMS1 or SMS1) as a susceptibility factor for RV infection. Genetic knockout of SGMS1 rendered JAR cells resistant to infection by RV. The re-introduction of SGMS1 restored cellular susceptibility to RV infection. The restricted step of RV infection was post-endocytosis processes associated with the endosomal acidification. In the late phase of the RV replication cycle, the maintenance of viral persistence was disrupted, partly due to the attenuated viral gene expression. Our results shed light on the unique regulation of RV replication by a host factor during the early and late phases of viral life cycle.

Naturally Occurring Herbs and their Bioactive Metabolites: Potential Targets and Signaling Pathways of Antiviral Agents.

Viruses significantly impact global health because they are the leading cause of death everywhere they are found. Despite the rapid development of human healthcare, more effective viricidal or antiviral therapies must be developed. The need to find safe, novel, and effective alternatives against viral diseases is heightened by the rapid emergence of resistance to, and the high cost of, synthetic antiviral drug(s). The development of novel multi-target antiviral compounds that affect multiple steps of the viral life cycle and host proteins has benefited tremendously from looking to nature for guidance and inspiration. Hundreds of natural molecules are preferred over synthetic drugs because of concerns regarding efficacy and safety and a high resistance rate to conventional therapies. In addition, naturally occurring antiviral agents have demonstrated reasonable antiviral value in both animal and human studies. Therefore, finding new antiviral drugs is crucial, and natural products provide an excellent opportunity. This brief review examines the evidence of antiviral effects exhibited by various plants and herbs.