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1.

Background

While the RNA world hypothesis is widely accepted, it is still far from complete: the existence of self-replicating ribozyme, consisting of potentially hundreds of nucleotides, is a core assumption for the majority of RNA world models. The appearance of such long RNA molecules under prebiotic conditions is not self-evident. Recombination seems to be a plausible way of creating RNA diversity, resulting in the appearance of functional RNAs, capable of self-replicating.

Methods

We report here on the study of recombination process modelled with two 96 nts RNA fragments. Detection of recombination products was performed with RT-PCR followed by TA-cloning and Sanger sequencing.

Results

A wide range of recombinant products was detected. We found that (i) the most efficient ligation was observed for RNA species forming bulges or internal loops, with ligation partners located within the loop; (ii) a strong preference was observed for formation of a few types of major products with a large variety of minor products; (iii) ligation could occur with participation of either 2′,3′-cyclophosphate or 5′-ppp; (iv) the presence of key reaction components, i.e. 5′ppp-RNAs, enabled the formation of additional types of product; (v) molecular dynamics simulations of one of the most abundant products suggests that the ligation results in a preferable formation of 2′-5′- rather than 3′-5′-linkages.

Conclusions

The study demonstrates regularities of new RNA molecules formation with non-enzymatic recombination process.

General significance

Our findings provide new data supporting the RNA World hypothesis and show the way of new RNA sequences emergence under prebiotic conditions.  相似文献   

2.

Background

Next generation sequencing (NGS) methods have significantly contributed to a paradigm shift in genomic research for nearly a decade now. These methods have been useful in studying the dynamic interactions between RNA viruses and human hosts.

Scope of the review

In this review, we summarise and discuss key applications of NGS in studying the host – pathogen interactions in RNA viral infections of humans with examples.

Major conclusions

Use of NGS to study globally relevant RNA viral infections have revolutionized our understanding of the within host and between host evolution of these viruses. These methods have also been useful in clinical decision-making and in guiding biomedical research on vaccine design.

General significance

NGS has been instrumental in viral genomic studies in resolving within-host viral genomic variants and the distribution of nucleotide polymorphisms along the full-length of viral genomes in a high throughput, cost effective manner. In the future, novel advances such as long read, single molecule sequencing of viral genomes and simultaneous sequencing of host and pathogens may become the standard of practice in research and clinical settings. This will also bring on new challenges in big data analysis.  相似文献   

3.
4.
5.
李静秋  杨杰  周平  乐燕萍  龚朝辉 《遗传》2015,37(8):756-764
最新研究表明,RNA之间可以通过竞争结合共同的microRNA反应元件(microRNA response element, MRE)实现相互调节,这种调控模式构成竞争性内源RNA(Competing endogenous RNA, ceRNA)。已发现的ceRNA包括蛋白编码mRNA和非编码RNA,其中后者包括假基因转录物、长链非编码RNA(Long non-coding RNA, lncRNA)、环状RNA(Circular RNA, circRNA)等。文章主要从ceRNA分类的角度,阐述各类ceRNA构成的调控网络发挥的生物学功能在病理和生理相关过程中的作用,以及可能影响ceRNA调控有效性的因素。  相似文献   

6.

Background

Nucleic acids are now important targets for therapeutic intervention. Alkaloids are an important class of molecules that have myriad therapeutic utility. Isoquinoline and benzophenanthridine alkaloids exhibit multiple pharmacological activities which are often related to their strong nucleic acid binding abilities. Therefore, a review of their interaction aspects with varying nucleic acid structures is essential for rational design and development as therapeutic agents.

Scope of the review

This work reviews the interaction of various therapeutically important isoquinoline and benzophenanthridine alkaloids with nucleic acids. The review lends insights into the molecular aspects of the interaction that is critical from the perspective of designing better therapeutics.

Major conclusions

This review provides a concise report on the recent developments and advancements on the interaction of various alkaloids with natural and synthetic nucleic acids. The review focuses on the mode, mechanism, specificity, conformational aspects and energetics of the interaction that will be helpful in the design and synthesis nucleic acid targeted alkaloid analogs.

General significance

The molecular aspects of the interaction presented here will benefit the development of effective drugs for many diseases. The fundamental results discussed in this review can serve as a database for the design and development of futuristic nucleic acid based small molecule therapeutics.  相似文献   

7.

Background

Nucleophosmin-1 (NPM1) is an abundant multifunctional protein, implicated in a variety of biological processes and in the pathogenesis of several human malignancies. Its C-terminal domain (CTD) is endowed with a three helix bundle and we demonstrated that several regions within it, associated with acute myeloid leukemia (AML), have a strong tendency to form beta amyloid-like assemblies toxic for cells. The central helix of the bundle (H2) resulted the most amyloidgenic region; here we aim to model the cytoxicity processes of the H2 sequence and getting clues of a potential involvement in toxicity of the interaction between CTDs and cellular membranes.

Methods

We investigated the interaction of CTD-NPM1 regions with model membranes through fluorescence, SPR, CD and ESR spectroscopies and the localization of NPM1 by immune-fluorescence in leukemic cells.

Results

Our findings indicate that investigated regions are able to interact with membranes with different mechanisms and outlined the importance of the presence of cholesterol.

Conclusions

H2 showed a preference of interaction with membrane containing cholesterol determining a sensitive fluidification of the bilayer, while N-term H2 causes a stiffening of central and outer regions of the lipid system. Noticeably, NPM1 mut A demonstrated to thicken at the plasma membrane, differently from wt. These findings were corroborated by diverse mechanisms of interaction of CTDs toward membrane models in vitro.

General significance

This study suggests that the direct interaction of several regions of NPM1CTD with cellular membranes could be implicated in diseases where NPM1 is mutated and/or where its overexpression is cytoxic.  相似文献   

8.

Background

A healthy human can produce over 1?×?1015 blood cells throughout their life. This remarkable amount of biomass requires a concomitantly vast amount of iron to generate functional haemoglobin and functional erythrocytes.

Scope of the review

Erythroblasts form multicellular clusters with macrophages in the foetal liver, bone marrow and spleen termed erythroblastic islands. How the central erythroblastic island macrophage co-ordinates the supply of iron to the developing erythroblasts will be a central focus of this review.

Major conclusion

Despite being studied for over 60?years, the mechanisms by which the erythroblastic island niche serves to control erythroid cell iron metabolism are poorly resolved.

General significance

Over 2 billion people suffer from some form of anaemia. Iron deficiency anaemia is the most prevalent form of anaemia. Therefore, understanding the processes by which iron is trafficked to, and metabolised in developing erythrocytes, is crucially important.  相似文献   

9.
10.

Background

Selenoprotein synthesis requires the reinterpretation of a UGA stop codon as one that encodes selenocysteine (Sec), a process that requires a set of dedicated translation factors. Among the mammalian selenoproteins, Selenoprotein P (SELENOP) is unique as it contains a selenocysteine-rich domain that requires multiple Sec incorporation events.

Scope of review

In this review we elaborate on new data and current models that provide insight into how SELENOP is made.

Major conclusions

SELENOP synthesis requires a specific set of factors and conditions.

General significance

As the key protein required for proper selenium distribution, SELENOP stands out as a lynchpin selenoprotein that is essential for male fertility, proper neurologic function and selenium metabolism.  相似文献   

11.

Background

Selenoproteins (25 genes in human) co-translationally incorporate selenocysteine using a UGA codon, normally used as a stop signal. The human selenoproteome is primarily regulated by selenium bioavailability with a tissue-specific hierarchy.

Methods

We investigated the hierarchy of selenoprotein expression in response to selenium concentration variation in four cell lines originating from kidney (HEK293, immortalized), prostate (LNCaP, cancer), skin (HaCaT, immortalized) and liver (HepG2, cancer), using complementary analytical methods. We performed (i) enzymatic activity, (ii) RT-qPCR, (iii) immuno-detection, (iv) selenium-specific mass spectrometric detection after non-radioactive 76Se labeling of selenoproteins, and (v) luciferase-based reporter constructs in various cell extracts.

Results

We characterized cell-line specific alterations of the selenoproteome in response to selenium variation that, in most of the cases, resulted from a translational control of gene expression. We established that UGA-selenocysteine recoding efficiency, which depends on the nature of the SECIS element, dictates the response to selenium variation.

Conclusions

We characterized that selenoprotein hierarchy is cell-line specific with conserved features. This analysis should be done prior to any experiments in a novel cell line.

General significance

We reported a strategy based on complementary methods to evaluate selenoproteome regulation in human cells in culture.  相似文献   

12.

Background

The abuse of opioids, such as morphine and phentanyl or other drugs as heroin is a social and health problem that affects an increasing number of people each year. The activation of the mu opioid receptor triggers several molecular changes that alter the expression of diverse genes, including miRNAs. The dysregulation of these molecules could explain some of the developmental alterations that are induced after drug intake. In addition, the Notch signaling cascade has also been related to alterations on these processes.

Methods

Zebrafish embryos and SH-SY5Y cells were used to assess the effects of opioid and Notch signaling on the expression on miR-29a and miR-212/132 by qPCR and ChIP-qPCR. Notch1 expression was analyzed using in situ hybridization on 24 hpf zebrafish embryos. In addition, OPRM1 and NICD levels were measured using western blot on the cultured cells to determine the cross-talk between the two pathways.

Results

We have observed changes in the levels of miR-212/132 after administrating DAPT to zebrafish embryos indicating that this pathway could be regulating mu opioid receptor expression. In addition, the ISH experiment showed changes in Notch1 expression after morphine and DAPT administration. Moreover, morphine affects the expression of miR-29a through NF-κB, therefore controlling the cleavage and activation of Notch through ADAM12 expression.

Conclusions

This study shows that these two pathways are closely related, and could explain the alterations triggered in the early stages of the development of addiction.

General significance

Opioid and Notch pathway are reciprocally regulated by the miRNAs 212/132 and 29a.  相似文献   

13.

Background

Argonaute proteins are key in RNA silencing. In Drosophila melanogaster, the five proteins of the Argonaute family participate in the pathways and mechanisms mediated by three types of small RNAs: piRNAs, miRNAs, and siRNAs. Two Argonaute proteins, Argonaute 1 (Ago1) and Argonaute 2 (Ago2), are associated with miRNA and siRNA mechanisms, which are the most thoroughly studied. The available data points to a sorting specialization of Ago1 for miRNAs and Ago2 for siRNAs. However, this has been demonstrated only in D. melanogaster, one of the most modified insects, which emerged some 100 million years ago. Thus, an important question is whether this association of Ago1 with miRNAs and Ago2 with siRNAs occurs generally in insects, or was a specific innovation in higher flies.

Methods

We addressed this question by using RNAi approaches and studying Ago1 and Ago2 functions in the German cockroach, Blattella germanica, a much less modified insect that emerged some 320 million years ago.

Results

The results showed that B. germanica does preferentially use Ago1 in the miRNA pathway, but can also use Ago2 in some cases. Conversely, Ago2 operates in the RNAi, in siRNA sorting, whereas Ago1 seems to have no relevant role in this process.

Conclusions and general significance

These basic associations are equivalent to those observed in D. melanogaster, implying that they have been evolutionary conserved from at least cockroach to flies, and possibly stem from the last common ancestor of extant insects.  相似文献   

14.
15.

Background

Spontaneous intracranial hypotension (SIH) is caused by cerebrospinal fluid (CSF) leakage. Definitive diagnosis can be difficult by clinical examinations and imaging studies.

Methods

SIH was diagnosed with the following criteria: (i) evidence of CSF leakage by cranial magnetic resonance imaging (MRI) findings of intracranial hypotension and/or low CSF opening pressure; (ii) no recent history of dural puncture. We quantified CSF proteins by ELISA or Western blotting.

Results

Comparing with non-SIH patients, SIH patients showed significant increase of brain-derived CSF glycoproteins such as lipocalin-type prostaglandin D synthase (L-PGDS), soluble protein fragments generated from amyloid precursor protein (sAPP) and “brain-type” transferrin (Tf). Serum-derived proteins such as albumin, immunoglobulin G, and serum Tf were also increased. A combination of L-PGDS and brain-type Tf differentiated SIH from non-SIH with sensitivity 94.7% and specificity 72.6%.

Conclusion

L-PGDS and brain-type Tf can be biomarkers for diagnosing SIH.

General significance

L-PGDS and brain-type Tf biosynthesized in the brain appears to be markers for abnormal metabolism of CSF.  相似文献   

16.

Background

Endoglin (CD105) is overexpressed on tumor cells and tumor vasculatures, making it a potential target for diagnostic imaging and therapy of different neoplasms. Therefore, studies on nanocarrier systems designed for endoglin-directed diagnostic and drug delivery purposes would expose the feasibility of targeting endoglin with therapeutics.

Methods

Liposomes carrying high concentrations of a near-infrared fluorescent dye in the aqueous interior were prepared by the lipid film hydration and extrusion procedure, then conjugated to single chain antibody fragments either selective for murine endoglin (termed mEnd-IL) or directed towards human endoglin (termed hEnd-IL). A combination of Dynamic Light Scattering, electron microscopy, cell binding and uptake assays, confocal microscopy and in vivo fluorescence imaging of mice bearing xenografted human breast cancer and human fibrosarcoma models were implemented to elucidate the potentials of the liposomes.

Results

The mEnd-IL and hEnd-IL were highly selective for the respective murine- and human endoglin expressing cells in vitro and in vivo. Hence, the hEnd-IL bound distinctly to the tumor cells and enabled suitable fluorescence imaging of the tumors, whereas the mEnd-IL bound the tumor vasculature, but also to the liver, kidney and lung vasculature of mice.

Conclusions

The work highlights key differences between targeting vascular (murine) and neoplastic (human) endoglin in animal studies, and suggests that the hEnd-IL can serve as a delivery system that targets human endoglin overexpressed in pathological conditions.

General significance

The endoglin-targeting liposomes presented herewith represent strategic tools for the future implementation of endoglin-directed neoplastic and anti-angiogenic therapies.  相似文献   

17.

Background

The human body contains numerous long-lived proteins which deteriorate with age, typically by racemisation, deamidation, crosslinking and truncation. Previously we elucidated one reaction responsible for age-related crosslinking, the spontaneous formation of dehydroalanine (DHA) intermediates from phosphoserine and cysteine. This resulted in non-disulphide covalent crosslinks. The current paper outlines a novel posttranslational modification (PTM) in human proteins, which involves the addition of dehydroalanylglycine (DHAGly) to Lys residues.

Methods

Human lens digests were examined by mass spectrometry for the presence of (DHA)Gly (+144.0535?Da) adducts to Lys residues. Peptide model studies were undertaken to elucidate the mechanism of formation.

Results

In the lens, this PTM was detected at 18 lysine sites in 7 proteins. Using model peptides, a pathway for its formation was found to involve initial formation of the glutathione degradation product, γ-Glu(DHA)Gly from oxidised glutathione (GSSG). Once the Lys adduct formed, the Glu residue was lost in a hydrolytic mechanism apparently catalysed by the ε-amino group of the Lys.

Conclusions

This discovery suggests that within cells, the functional groups of amino acids in proteins may be susceptible to modification by reactive metabolites derived from GSSG.

General significance

Our finding demonstrates a novel +144.0535?Da PTM arising from the breakdown of oxidised glutathione.  相似文献   

18.

Background

The development of approaches that increase therapeutic effects of anti-cancer drugs is one of the most important tasks of oncology. Caloric restriction in vivo or serum deprivation (SD) in vitro has been shown to be an effective tool for sensitizing cancer cells to chemotherapeutic drugs. However, the detailed mechanisms underlying the enhancement of apoptosis in cancer cells by SD remain to be elucidated.

Methods

Flow cytometry, caspase activity assay and western blotting were used for cell death rate evaluation. Western blotting, gel-filtration, siRNA approach and qRT-PCR were used to elucidate the mechanism underlying cell death potentiation upon SD.

Results

We demonstrated that SD sensitizes cancer cells to treatment with chemotherapeutic agent cisplatin. This effect is independent on activation of caspases-2 and -8, apical caspases triggering apoptosis in response to genotoxic stress. SD potentiates cell death via downregulation of the anti-apoptotic protein Mcl-1. In fact, SD reduces the Mcl-1 mRNA level, which consequently decreases the Mcl-1 protein level and renders cells more susceptible to apoptosis induction via the formation of apoptosome.

Conclusions

Mcl-1 protein is an important regulator of sensitivity of cancer cells to apoptotic stimuli upon SD.

General significance

This study identifies Mcl-1 as a new target for the sensitization of human cancer cells to cell death by SD, which is of great significance for the development of efficient anti-cancer therapies.  相似文献   

19.

Background

Nicotinamide adenine dinucleotide (NAD+) is an essential pyridine nucleotide that is currently investigated as an important target to extend lifespan and health span. Age-related NAD+ depletion due to the accumulation of oxidative stress is associated with reduced energy production, impaired DNA repair and genomic instability.

Scope of review

NAD+ levels can be elevated therapeutically using NAD+ precursors or through lifestyle modifications including exercise and caloric restriction. However, high amounts of NAD+ may be detrimental in cancer progression and may have deleterious immunogenic roles.

Major conclusions

Standardized quantitation of NAD+ and related metabolites may therefore represent an important component of NAD+ therapy.

General significance

Quantitation of NAD+ may serve dual roles not only as an ageing biomarker, but also as a diagnostic tool for the prevention of malignant disorders.  相似文献   

20.

Background

Human RNase6 is a small cationic antimicrobial protein that belongs to the vertebrate RNaseA superfamily. All members share a common catalytic mechanism, which involves a conserved catalytic triad, constituted by two histidines and a lysine (His15/His122/Lys38 in RNase6 corresponding to His12/His119/Lys41 in RNaseA). Recently, our first crystal structure of human RNase6 identified an additional His pair (His36/His39) and suggested the presence of a secondary active site.

Methods

In this work we have explored RNase6 and RNaseA subsite architecture by X-ray crystallography, site-directed mutagenesis and kinetic characterization.

Results

The analysis of two novel crystal structures of RNase6 in complex with phosphate anions at atomic resolution locates a total of nine binding sites and reveals the contribution of Lys87 to phosphate-binding at the secondary active center. Contribution of the second catalytic triad residues to the enzyme activity is confirmed by mutagenesis. RNase6 catalytic site architecture has been compared with an RNaseA engineered variant where a phosphate-binding subsite is converted into a secondary catalytic center (RNaseA-K7H/R10H).

Conclusions

We have identified the residues that participate in RNase6 second catalytic triad (His36/His39/Lys87) and secondary phosphate-binding sites. To note, residues His39 and Lys87 are unique within higher primates. The RNaseA/RNase6 side-by-side comparison correlates the presence of a dual active site in RNase6 with a favored endonuclease-type cleavage pattern.

General significance

An RNase dual catalytic and extended binding site arrangement facilitates the cleavage of polymeric substrates. This is the first report of the presence of two catalytic centers in a single monomer within the RNaseA superfamily.  相似文献   

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