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- LIDYL, CEA, CNRS, Université Paris-Saclay, CEA Saclay 91191 Gif-sur-Yvette France (1)
- Lehrstuhl für BioMolekulare Optik, Ludwig-Maximilians-Universität München (1)
- NanoOptics & Biophotonics Group, Experimental Physics 5, Universität Würzburg (1)
Background
Epigenetic mechanisms may play a major role in the biological embedding of early-life stress (ELS). One proposed mechanism is that glucocorticoid (GC) release following ELS exposure induces long-lasting alterations in DNA methylation (DNAm) of important regulatory genes of the stress response. Here, we investigate the dynamics of GC-dependent methylation changes in key regulatory regions of the FKBP5 locus in which ELS-associated DNAm changes have been reported.
Results
We repeatedly measured DNAm in human peripheral blood samples from 2 independent cohorts exposed to the GC agonist dexamethasone (DEX) using a targeted bisulfite sequencing approach, complemented by data from Illumina 450K arrays. We detected differentially methylated CpGs in enhancers co-localizing with GC receptor binding sites after acute DEX treatment (1 h, 3 h, 6 h), which returned to baseline levels within 23 h. These changes withstood correction for immune cell count differences. While we observed main effects of sex, age, body mass index, smoking, and depression symptoms on FKBP5 methylation levels, only the functional FKBP5 SNP (rs1360780) moderated the dynamic changes following DEX. This genotype effect was observed in both cohorts and included sites previously shown to be associated with ELS.
Conclusion
Our study highlights that DNAm levels within regulatory regions of the FKBP5 locus show dynamic changes following a GC challenge and suggest that factors influencing the dynamics of this regulation may contribute to the previously reported alterations in DNAm associated with current and past ELS exposure.
The novel PET probe 2-deoxy-2-18F-fluoro-D-sorbitol (18F-FDS) has demonstrated favorable renal kinetics in animals. We aimed to elucidate its imaging properties in two human volunteers. 18F-FDS was produced by a simple one-step reduction from 18F-FDG. On dynamic renal PET, the cortex was delineated and activity gradually transited in the parenchyma, followed by radiotracer excretion. No adverse effects were reported. Given the higher spatiotemporal resolution of PET relative to conventional scintigraphy, 18F-FDS PET offers a more thorough evaluation of human renal kinetics. Due to its simple production from 18F-FDG, 18F-FDS is virtually available at any PET facility with radiochemistry infrastructure.
Standardized reporting is more and more routinely implemented in clinical practice and such structured reports have a major impact on a large variety of medical fields, e.g. laboratory medicine, pathology, and, recently, radiology. Notably, the field of nuclear medicine is constantly evolving, as novel radiotracers for numerous clinical applications are developed. Thus, framework systems for standardized reporting in this field may a) increase clinical acceptance of new radiotracers, b) allow for inter- and intra-center comparisons for quality assurance, and c) may be used in (global) multi-center studies to ensure comparable results and enable efficient data abstraction. In the last two years, several standardized framework systems for positron emission tomography (PET) radiotracers with potential theranostic applications have been proposed. These include systems for prostate-specific membrane antigen (PSMA)-targeted PET agents for the diagnosis and treatment of prostate cancer (PCa) and somatostatin receptor (SSTR)-targeted PET agents for the diagnosis and treatment of neuroendocrine neoplasias. In the present review, those standardized framework systems for PSMA- and SSTR-targeted PET will be briefly introduced followed by an overview of their advantages and limitations. In addition, potential applications will be defined, approaches to validate such concepts will be proposed, and future perspectives will be discussed.
Converging evidence suggests a role of serotonin (5-hydroxytryptamine, 5-HT) and tryptophan hydroxylase 2 (TPH2), the rate-limiting enzyme of 5-HT synthesis in the brain, in modulating long-term, neurobiological effects of early-life adversity. Here, we aimed at further elucidating the molecular mechanisms underlying this interaction, and its consequences for socio-emotional behaviors, with a focus on anxiety and social interaction. In this study, adult, male Tph2 null mutant (Tph2\(^{-/-}\)) and heterozygous (Tph2\(^{+/-}\)) mice, and their wildtype littermates (Tph2\(^{+/+}\)) were exposed to neonatal, maternal separation (MS) and screened for behavioral changes, followed by genome-wide RNA expression and DNA methylation profiling. In Tph2\(^{-/-}\) mice, brain 5-HT deficiency profoundly affected socio-emotional behaviors, i.e., decreased avoidance of the aversive open arms in the elevated plus-maze (EPM) as well as decreased prosocial and increased rule breaking behavior in the resident-intruder test when compared to their wildtype littermates. Tph2\(^{+/-}\) mice showed an ambiguous profile with context-dependent, behavioral responses. In the EPM they showed similar avoidance of the open arm but decreased prosocial and increased rule breaking behavior in the resident-intruder test when compared to their wildtype littermates. Notably, MS effects on behavior were subtle and depended on the Tph2 genotype, in particular increasing the observed avoidance of EPM open arms in wildtype and Tph2\(^{+/-}\) mice when compared to their Tph2\(^{-/-}\) littermates. On the genomic level, the interaction of Tph2 genotype with MS differentially affected the expression of numerous genes, of which a subset showed an overlap with DNA methylation profiles at corresponding loci. Remarkably, changes in methylation nearby and expression of the gene encoding cholecystokinin, which were inversely correlated to each other, were associated with variations in anxiety-related phenotypes. In conclusion, next to various behavioral alterations, we identified gene expression and DNA methylation profiles to be associated with TPH2 inactivation and its interaction with MS, suggesting a gene-by-environment interaction-dependent, modulatory function of brain 5-HT availability.
Mobile health interventions (i.e., “apps”) are used to address mental health and are an increasingly popular method available to both individuals and organizations to manage workplace stress. However, at present, there is a lack of research on the effectiveness of mobile health interventions in counteracting or improving stress-related health problems, particularly in naturalistic, non-clinical settings. This project aimed at validating a mobile health intervention (which is theoretically grounded in the Job Demands-Resources Model) in preventing and managing stress at work. Within the mobile health intervention, employees make an evidence-based, personalized, psycho-educational journey to build further resources, and thus, reduce stress. A large-scale longitudinal randomized control trial, conducted with six European companies over 6 weeks using four measurement points, examined indicators of mental health via measures of stress, wellbeing, resilience, and sleep. The data were analyzed by means of hierarchical multilevel models for repeated measures, including both self-report measures and user behavior metrics from the app. The results (n = 532) suggest that using the mobile health intervention (vs. waitlist control group) significantly improved stress and wellbeing over time. Higher engagement in the intervention increased the beneficial effects. Additionally, use of the sleep tracking function led to an improvement in sleeping troubles. The intervention had no effects on measures of physical health or social community at work. Theoretical and practical implications of these findings are discussed, focusing on benefits and challenges of using technological solutions for organizations to support individuals’ mental health in the workplace.
Brain serotonin (5-hydroxytryptamine, 5-HT) system dysfunction is implicated in exaggerated fear responses triggering various anxiety-, stress-, and trauma-related disorders. However, the underlying mechanisms are not well understood. Here, we investigated the impact of constitutively inactivated 5-HT synthesis on context-dependent fear learning and extinction using tryptophan hydroxylase 2 (Tph2) knockout mice. Fear conditioning and context-dependent fear memory extinction paradigms were combined with c-Fos imaging and electrophysiological recordings in the dorsal hippocampus (dHip). Tph2 mutant mice, completely devoid of 5-HT synthesis in brain, displayed accelerated fear memory formation and increased locomotor responses to foot shock. Furthermore, recall of context-dependent fear memory was increased. The behavioral responses were associated with increased c-Fos expression in the dHip and resistance to foot shock-induced impairment of hippocampal long-term potentiation (LTP). In conclusion, increased context-dependent fear memory resulting from brain 5-HT deficiency involves dysfunction of the hippocampal circuitry controlling contextual representation of fear-related behavioral responses.
We present a theoretical study on exciton–exciton annihilation (EEA) in a molecular dimer. This process is monitored using a fifth-order coherent two-dimensional (2D) spectroscopy as was recently proposed by Dostál et al. [Nat. Commun. 9, 2466 (2018)]. Using an electronic three-level system for each monomer, we analyze the different paths which contribute to the 2D spectrum. The spectrum is determined by two entangled relaxation processes, namely, the EEA and the direct relaxation of higher lying excited states. It is shown that the change of the spectrum as a function of a pulse delay can be linked directly to the presence of the EEA process.
We present a theoretical study on exciton–exciton annihilation (EEA) in a molecular dimer. This process is monitored using a fifth-order coherent two-dimensional (2D) spectroscopy as was recently proposed by Dostál et al. [Nat. Commun. 9, 2466 (2018)]. Using an electronic three-level system for each monomer, we analyze the different paths which contribute to the 2D spectrum. The spectrum is determined by two entangled relaxation processes, namely, the EEA and the direct relaxation of higher lying excited states. It is shown that the change of the spectrum as a function of a pulse delay can be linked directly to the presence of the EEA process.
In the treatment of bone non-unions, an alternative to bone autografts is the use of bone morphogenetic proteins (BMPs), e.g., BMP–2, BMP–7, with powerful osteoinductive and osteogenic properties. In clinical settings, these osteogenic factors are applied using absorbable collagen sponges for local controlled delivery. Major side effects of this strategy are derived from the supraphysiological doses of BMPs needed, which may induce ectopic bone formation, chronic inflammation, and excessive bone resorption. In order to increase the efficiency of the delivered BMPs, we designed cryostructured collagen scaffolds functionalized with hydroxyapatite, mimicking the structure of cortical bone (aligned porosity, anisotropic) or trabecular bone (random distributed porosity, isotropic). We hypothesize that an anisotropic structure would enhance the osteoconductive properties of the scaffolds by increasing the regenerative performance of the provided rhBMP–2. In vitro, both scaffolds presented similar mechanical properties, rhBMP–2 retention and delivery capacity, as well as scaffold degradation time. In vivo, anisotropic scaffolds demonstrated better bone regeneration capabilities in a rat femoral critical-size defect model by increasing the defect bridging. In conclusion, anisotropic cryostructured collagen scaffolds improve bone regeneration by increasing the efficiency of rhBMP–2 mediated bone healing.
In this work, two new quadrupolar A-π-D-π-A chromophores have been prepared featuring a strongly electron- donating diborene core and strongly electron-accepting dimesitylboryl F(BMes2) and bis(2,4,6-tris(trifluoromethyl)phenyl)boryl (BMes2) end groups. Analysis of the compounds by NMR spectroscopy, X-ray crystallography, cyclic voltammetry and UV-vis-NIR absorption and emission spectroscopy indicated that the compounds possess extended conjugated π-systems spanning their B4C8 cores. The combination of exceptionally potent π-donor (diborene) and π- acceptor (diarylboryl) groups, both based on trigonal boron, leads to very small HOMO-LUMO gaps, resulting in strong absorption in the near-IR region with maxima in THF at 840 and 1092 nm, respectively, and very high extinction coefficients of ca. 120,000 M-1cm-1. Both molecules also display weak near-IR fluorescence with small Stokes shifts.
Structure-fluorescence activation relationships of a large Stokes shift fluorogenic RNA aptamer
(2019)
The Chili RNA aptamer is a 52 nt long fluorogen-activating RNA aptamer (FLAP) that confers fluorescence to structurally diverse derivatives of fluorescent protein chromophores. A key feature of Chili is the formation of highly stable complexes with different ligands, which exhibit bright, highly Stokes-shifted fluorescence emission. In this work, we have analyzed the interactions between the Chili RNA and a family of conditionally fluorescent ligands using a variety of spectroscopic, calorimetric and biochemical techniques to reveal key structure - fluorescence activation relationships (SFARs). The ligands under investigation form two categories with emission maxima of ~540 nm or ~590 nm, respectively, and bind with affinities in the nanomolar to low-micromolar range. Isothermal titration calorimetry was used to elucidate the enthalpic and entropic contributions to binding affinity for a cationic ligand that is unique to the Chili aptamer. In addition to fluorescence activation, ligand binding was also observed by NMR spectroscopy, revealing characteristic signals for the formation of a G-quadruplex only upon ligand binding. These data shed light on the molecular features required and responsible for the large Stokes shift and the strong fluorescence enhancement of red and green emitting RNA-chromophore complexes.
Research on facial emotion expression has mostly focused on emotion recognition, assuming that a small number of discrete emotions is elicited and expressed via prototypical facial muscle configurations as captured in still photographs. These are expected to be recognized by observers, presumably via template matching. In contrast, appraisal theories of emotion propose a more dynamic approach, suggesting that specific elements of facial expressions are directly produced by the result of certain appraisals and predicting the facial patterns to be expected for certain appraisal configurations. This approach has recently been extended to emotion perception, claiming that observers first infer individual appraisals and only then make categorical emotion judgments based on the estimated appraisal patterns, using inference rules. Here, we report two related studies to empirically investigate the facial action unit configurations that are used by actors to convey specific emotions in short affect bursts and to examine to what extent observers can infer a person's emotions from the predicted facial expression configurations. The results show that (1) professional actors use many of the predicted facial action unit patterns to enact systematically specified appraisal outcomes in a realistic scenario setting, and (2) naïve observers infer the respective emotions based on highly similar facial movement configurations with a degree of accuracy comparable to earlier research findings. Based on estimates of underlying appraisal criteria for the different emotions we conclude that the patterns of facial action units identified in this research correspond largely to prior predictions and encourage further research on appraisal-driven expression and inference.
Both low-level physical saliency and social information, as presented by human heads or bodies, are known to drive gaze behavior in free-viewing tasks. Researchers have previously made use of a great variety of face stimuli, ranging from photographs of real humans to schematic faces, frequently without systematically differentiating between the two. In the current study, we used a Generalized Linear Mixed Model (GLMM) approach to investigate to what extent schematic artificial faces can predict gaze when they are presented alone or in competition with real human faces. Relative differences in predictive power became apparent, while GLMMs suggest substantial effects for real and artificial faces in all conditions. Artificial faces were accordingly less predictive than real human faces but still contributed significantly to gaze allocation. These results help to further our understanding of how social information guides gaze in complex naturalistic scenes.
Reactive hydrocarbon molecules like radicals, biradicals and carbenes are not only key players in combustion processes and interstellar and atmospheric chemistry, but some of them are also important intermediates in organic synthesis. These systems typically possess many low-lying, strongly coupled electronic states. After light absorption, this leads to rich photodynamics characterized by a complex interplay of nuclear and electronic motion, which is still not comprehensively understood and not easy to investigate both experimentally and theoretically. In order to elucidate trends and contribute to a more general understanding, we here review our recent work on excited-state dynamics of open-shell hydrocarbon species using time-resolved photoelectron spectroscopy and field-induced surface hopping simulations, and report new results on the excited-state dynamics of the tropyl and the 1-methylallyl radical. The different dynamics are compared, and the difficulties and future directions of time-resolved photoelectron spectroscopy and excited state dynamics simulations of open-shell hydrocarbon molecules are discussed.
Auxin is a molecule, which controls many aspects of plant development through both transcriptional and non-transcriptional signaling responses. AUXIN BINDING PROTEIN1 (ABP1) is a putative receptor for rapid non-transcriptional auxin-induced changes in plasma membrane depolarization and endocytosis rates. However, the mechanism of ABP1-mediated signaling is poorly understood. Here we show that membrane depolarization and endocytosis inhibition are ABP1-independent responses and that auxin-induced plasma membrane depolarization is instead dependent on the auxin influx carrier AUX1. AUX1 was itself not involved in the regulation of endocytosis. Auxin-dependent depolarization of the plasma membrane was also modulated by the auxin efflux carrier PIN2. These data establish a new connection between auxin transport and non-transcriptional auxin signaling.
The lability of B=B, B-P and B-halide bonds is combined in the syntheses of the first diiododiborenes. In a series of reactivity tests, these diiododiborenes demonstrate cleavage of all six of their central bonds in different ways, leading to products of B=B hydrogenation and dihalogenation as well as halide exchange.
Hepatic activation of protein kinase C (PKC) isoforms by diacylglycerol (DAG) promotes insulin resistance and contributes to the development of type 2 diabetes (T2D). The closely related protein kinase D (PKD) isoforms act as effectors for DAG and PKC. Here, we showed that PKD3 was the predominant PKD isoform expressed in hepatocytes and was activated by lipid overload. PKD3 suppressed the activity of downstream insulin effectors including the kinase AKT and mechanistic target of rapamycin complex 1 and 2 (mTORC1 and mTORC2). Hepatic deletion of PKD3 in mice improved insulin-induced glucose tolerance. However, increased insulin signaling in the absence of PKD3 promoted lipogenesis mediated by SREBP (sterol regulatory element-binding protein) and consequently increased triglyceride and cholesterol content in the livers of PKD3-deficient mice fed a high-fat diet. Conversely, hepatic-specific overexpression of a constitutively active PKD3 mutant suppressed insulin-induced signaling and caused insulin resistance. Our results indicate that PKD3 provides feedback on hepatic lipid production and suppresses insulin signaling. Therefore, manipulation of PKD3 activity could be used to decrease hepatic lipid content or improve hepatic insulin sensitivity.
General and efficient tools for site-specific fluorescent or bioorthogonal labeling of RNA are in high demand. Here, we report direct in vitro selection, characterization, and application of versatile trans-acting 2'-5' adenylyl transferase ribozymes for covalent and site-specific RNA labeling. The design of our partially structured RNA pool allowed for in vitro evolution of ribozymes that modify a predetermined nucleotide in cis (i.e. intramolecular reaction), and were then easily engineered for applications in trans (i.e. in an intermolecular setup). The resulting ribozymes are readily designed for specific target sites in small and large RNAs and accept a wide variety of N6-modified ATP analogues as small molecule substrates. The most efficient new ribozyme (FH14) shows excellent specificity towards its target sequence also in the context of total cellular RNA.
The study of main-group molecules that behave and react similarly to transition-metal (TM) complexes has attracted significant interest in recent decades. Most notably, the attractive idea of replacing the all-too-often rare and costly metals from catalysis has motivated efforts to develop main-group-element-mediated reactions. Main-group elements, however, lack the electronic flexibility of TM complexes that arises from combinations of empty and filled d orbitals and that seem ideally suited to bind and activate many substrates. In this review, we look at boron, an element that despite its nonmetal nature, low atomic weight, and relative redox staticity has achieved great milestones in terms of TM-like reactivity. We show how in interelement cooperative systems, diboron molecules, and hypovalent complexes the fifth element can acquire a truly metallomimetic character. As we discuss, this character is powerfully demonstrated by the reactivity of boron-based molecules with H2, CO, alkynes, alkenes and even with N2.
Collective Response in DNA-Stabilized Silver Cluster Assemblies from First-Principles Simulations
(2019)
We investigate fluorescence resonant energy transfer and concurrent electron dynamics in a pair of DNA-stabilized silver clusters. For this purpose we introduce a methodology for the simulation of collective optoelectronic properties of coupled molecular aggregates starting from first-principles quantum chemistry, which can be further applied to a broad range of coupled molecular systems to study their electro-optical response. Our simulations reveal the existence of low-energy coupled excitonic states, which enable ultrafast energy transport between subunits, and give insight into the origin of the fluorescence signal in coupled DNA-stabilized silver clusters, which have been recently experimentally detected. Hence, we demonstrate the possibility of constructing ultrasmall energy transmission lines and optical converters based on these hybrid molecular systems.