The consumption of caffeine (an adenosine receptor antagonist) correlates inversely with depression and memory deterioration, and adenosine A2A receptor (A2AR) antagonists emerge as candidate ...therapeutic targets because they control aberrant synaptic plasticity and afford neuroprotection. Therefore we tested the ability of A2AR to control the behavioral, electrophysiological, and neurochemical modifications caused by chronic unpredictable stress (CUS), which alters hippocampal circuits, dampens mood and memory performance, and enhances susceptibility to depression. CUS for 3 wk in adult mice induced anxiogenic and helpless-like behavior and decreased memory performance. These behavioral changes were accompanied by synaptic alterations, typified by a decrease in synaptic plasticity and a reduced density of synaptic proteins (synaptosomal-associated protein 25, syntaxin, and vesicular glutamate transporter type 1), together with an increased density of A2AR in glutamatergic terminals in the hippocampus. Except for anxiety, for which results were mixed, CUS-induced behavioral and synaptic alterations were prevented by (i) caffeine (1 g/L in the drinking water, starting 3 wk before and continued throughout CUS); (ii) the selective A2AR antagonist KW6002 (3 mg/kg, p.o.); (iii) global A2AR deletion; and (iv) selective A2AR deletion in forebrain neurons. Notably, A2AR blockade was not only prophylactic but also therapeutically efficacious, because a 3-wk treatment with the A2AR antagonist SCH58261 (0.1 mg/kg, i.p.) reversed the mood and synaptic dysfunction caused by CUS. These results herald a key role for synaptic A2AR in the control of chronic stress-induced modifications and suggest A2AR as candidate targets to alleviate the consequences of chronic stress on brain function.
Glutamoptosis is the induction of apoptotic cell death as a consequence of the aberrant activation of glutaminolysis and mTORC1 signaling during nutritional imbalance in proliferating cells. The role ...of the bioenergetic sensor AMPK during glutamoptosis is not defined yet. Here, we show that AMPK reactivation blocks both the glutamine-dependent activation of mTORC1 and glutamoptosis in vitro and in vivo. We also show that glutamine is used for asparagine synthesis and the GABA shunt to produce ATP and to inhibit AMPK, independently of glutaminolysis. Overall, our results indicate that glutamine metabolism is connected with mTORC1 activation through two parallel pathways: an acute alpha-ketoglutarate-dependent pathway; and a secondary ATP/AMPK-dependent pathway. This dual metabolic connection between glutamine and mTORC1 must be considered for the future design of therapeutic strategies to prevent cell growth in diseases such as cancer.
Agro-industrial residues comprise a rich diversity of plant polymers and bioactive compounds, constituting promising sources for the development of materials, including bioplastics, and food ...supplements, among other applications. In particular, the polyester cutin is abundant in fruit peel, a plentiful constituent of pomace agro-industrial residues. The potential of diverse fruit pomaces as a source for the development of cutin-derived materials/products has been extensively sought out. This study expands the established knowledge: it sets proof of concept for the production of antimicrobial oligomers from cutin-rich materials isolated in a single step from tomato pomaces generated by two remote agro-industries. Specifically, it first analyzed how the chemical signature (nuclear magnetic resonance (NMR) and gas chromatography–mass spectrometry (GC–MS)) of a pomace (and of its major constituents) mirrors that of the corresponding cutin-rich material isolated using an ionic liquid extractant. The cutin-rich materials were then deconstructed (using mild hydrolyses), and the resultant mixtures were chemically characterized and screened for bactericidal activity against Escherichia coli and Staphylococcus aureus. The presence of esterified structures, linear and/or branched, likely comprising dioic acids as a major building block (but not exclusively) is a prerequisite for activity against E. coli but not against S. aureus that was susceptible to monomers as well. Further studies are required to optimize the production of broad bactericidal oligomers from any cutin-rich pomace source, moving ahead toward their circular usage.
In humans the stress response is known to be modulated to a great extent by psychological factors, particularly by the predictability and the perceived control that the subject has of the stressor. ...This psychological dimension of the stress response has also been demonstrated in animals phylogenetically closer to humans (i.e. mammals). However, its occurrence in fish, which represent a divergent vertebrate evolutionary lineage from that of mammals, has not been established yet, and, if present, would indicate a deep evolutionary origin of these mechanisms across vertebrates. Moreover, the fact that psychological modulation of stress is implemented in mammals by a brain cortical top-down inhibitory control over subcortical stress-responsive structures, and the absence of a brain cortex in fish, has been used as an argument against the possibility of psychological stress in fish, with implications for the assessment of fish sentience and welfare. Here, we have investigated the occurrence of psychological stress in fish by assessing how stressor controllability modulates the stress response in European seabass (Dicentrarchus labrax).
Fish were exposed to either a controllable or an uncontrollable stressor (i.e. possibility or impossibility to escape a signaled stressor). The effect of loss of control (possibility to escape followed by impossibility to escape) was also assessed. Both behavioral and circulating cortisol data indicates that the perception of control reduces the response to the stressor, when compared to the uncontrollable situation. Losing control had the most detrimental effect. The brain activity of the teleost homologues to the sensory cortex (Dld) and hippocampus (Dlv) parallels the uncontrolled and loss of control stressors, respectively, whereas the activity of the lateral septum (Vv) homologue responds in different ways depending on the gene marker of brain activity used.
These results suggest the psychological modulation of the stress response to be evolutionary conserved across vertebrates, despite being implemented by different brain circuits in mammals (pre-frontal cortex) and fish (Dld-Dlv).
Polyesters, as they exist in planta, are promising materials with which to begin the development of “green” replacements. Cutin and suberin, polyesters found ubiquitously in plants, are prime ...candidates. Samples enriched for plant polyesters, and in which their native backbones were largely preserved, were studied to identify “natural” structural features; features that influence critical physical properties. Quantitative nuclear magnetic resonance (NMR), differential scanning calorimetry (DSC), and X-ray scattering methods were used to quantify structure–property relationships in these polymeric materials. The degree of esterification, namely, the presence of acylglycerol linkages in suberin and of secondary esters in cutin, and the existence of mid-chain epoxide groups defining the packing of the aliphatic chains were observed. This packing determines polymer crystallinity, the resulting crystal structure, and the melting temperature. To evaluate the strength of this rule, tomato cutin from the same genotype, studying wild-type plants and two well-characterized mutants, was analyzed. The results show that cutin’s material properties are influenced by the amount of unbound aliphatic hydroxyl groups and by the length of the aliphatic chain. Collectively, the acquired data can be used as a tool to guide the selection of plant polyesters with precise structural features, and hence physicochemical properties.
Protein conformational disorders are characterized by disruption of protein folding and toxic accumulation of protein aggregates. Here we describe a sensitive and simple method to follow and monitor ...general protein aggregation in human cells. Heat shock protein 27 (HSP27) is an oligomeric small heat shock protein that binds and keeps unfolded proteins in a folding competent state. This high specificity of HSP27 for aggregated proteins can be explored to monitor aggregation in living cells by fusing it to a fluorescent protein as Green Fluorescent Protein (GFP). We have constructed a HeLa stable cell line expressing a HSP27:GFP chimeric reporter protein and after validation, this stable cell line is exposed to different agents that interfere with proteostasis, namely Arsenite, MG132, and Aβ‐peptide. Exposure to proteome destabilizers lead to re‐localization of HSP27:GFP fluorescence to foci, confirming that our reporter system is functional and can be used to detect and follow protein aggregation in living cells. This reporter is a valuable tool to setup wide‐genetic screens to identify genes and pathways involved in protein misfolding and aggregation.
Protein aggregation is a hallmark of several conformational disorders. We have developed a fluorescent sensor assay to detect protein misfolding in mammalian cells, by exploring the high specificity of HSP27 for aggregated proteins. The HSP27:GFP fusion sensor is not limited to amyloid aggregate detection and constitutes a valuable tool to perform high throughput fluorescent‐based screens to identify genes and/or chemical compounds that affect proteostasis.
Soybean (
Glycine max
) is an increasingly relevant crop due to its economic importance and also a model plant for the study of root symbiotic associations with nodule forming
rhizobia
. Plant ...polyesters mediate plant-microbe interactions with both pathogenic and beneficial microbes; suberin has been hypothesized to play a key role during the early steps of
rhizobia
attachment to the root. The downside is that suberin chemistry in soybean root is still scarcely studied. This study addresses this outstanding question by reporting a straightforward workflow for a speedy purification of suberin from soybean root and for its subsequent detailed chemical analysis. To purify suberin, cholinium hexanoate (an ionic liquid) was used as the catalyst. The ensuing suberin is highly esterified as observed by a precise Nuclear Magnetic Resonance quantification of each ester type, discriminating between primary and acylglycerol esters. Moreover, the composing hydrolysable monomers detected through GC-MS revealed that hexadecanoic acid is the most abundant monomer, similar to that reported before by others. Overall, this study highlights the adequacy of the ionic liquid catalyst for the isolation of suberin from soybean roots, where the polymer natural abundance is low, and builds new knowledge on the specificities of its chemistry; essential to better understand the biological roles of suberin in roots.
Diamagnetic metal complexes of phthalocyanines with n-butoxyl groups in all the α-benzo positions of the macrocycle skeleton, MPc(OBu)8, have strong near-infrared absorptions and intense ...fluorescences that are Stokes shifted by more than 15 nm. Interestingly, the silicon complex 6 is also remarkably photostable and nontoxic. The use of 6 in the fluorescence imaging of BALB/c mice bearing a 4T1-luc2 tumor in the mammary fat pad unambiguously revealed the presence of the tumor when it was only 1 mm in diameter and was not visible with the naked eye. Compound 6 has an intrinsic ability to accumulate in the tumor, adequate spectroscopic properties, and excellent stability to function as a NIR fluorescent label in the early detection of tumors.
Saprophytic fungi are able to catabolize many plant‐derived aromatics, including, for example, gallate. The catabolism of gallate in fungi is assumed to depend on the five main central pathways, ...i.e., of the central intermediates' catechol, protocatechuate, hydroxyquinol, homogentisate and gentisate, but a definitive demonstration is lacking. To shed light on this process, we analysed the transcriptional reprogramming of the growth of Aspergillus terreus on gallate compared with acetate as the control condition. Surprisingly, the results revealed that the five main central pathways did not exhibit significant positive regulation. Instead, an in‐depth analysis identified four highly expressed and upregulated genes that are part of a conserved gene cluster found in numerous species of fungi, though not in Aspergilli. The cluster comprises a monooxygenase gene and a fumarylacetoacetate hydrolase‐like gene, which are recognized as key components of catabolic pathways responsible for aromatic compound degradation. The other two genes encode proteins with no reported enzymatic activities. Through functional analyses of gene deletion mutants in Aspergillus nidulans, the conserved short protein with no known domains could be linked to the conversion of the novel metabolite 5‐hydroxydienelatone, whereas the DUF3500 gene likely encodes a ring‐cleavage enzyme for 1,2,3,5‐tetrahydroxybenzene. These significant findings establish the existence of a new 1,2,3,5‐tetrahydroxybenzene central pathway for the catabolism of gallate and related compounds (e.g. 2,4,6‐trihydroxybenzoate) in numerous fungi where this catabolic gene cluster was observed.
Our understanding of how fungi utilize gallate or other syringyl derivatives is, to date, scarce and mostly relies on unproven assumptions. This study demonstrates the existence of a new 1,2,3,5‐tetrahydroxybenzene central pathway for the catabolism of gallate and related compounds in numerous fungi. DUF3500 gene likely encodes a ring‐cleavage enzyme for the central intermediate. These findings have the potential to make a significant contribution to our understanding of key ecological and biotechnological processes in both fungi and bacteria.
The cuticle constitutes the outermost defensive barrier of most land plants. It comprises a polymeric matrix - cutin, surrounded by soluble waxes. Moreover, the cuticle constitutes the first line of ...defense against pathogen invasion, while also protecting the plant from many abiotic stresses. Aliphatic monomers in cutin have been suggested to act as immune elicitors in plants. This study analyses the potential of cutin oligomers to activate rapid signaling outputs reminiscent of pattern-triggered immunity (PTI) in the model plant Arabidopsis. Cutin oligomeric mixtures led to Ca2+ influx and MAPK activation. Comparable responses were measured for cutin, which was also able to induce a reactive oxygen species (ROS) burst. Furthermore, cutin oligomer treatment resulted in a unique transcriptional reprogramming profile, having many archetypal features of PTI. Targeted spectroscopic and spectrometric analyses of the cutin oligomers suggest that the elicitors compounds consist mostly of two up to three 10,16-dihydroxyhexadecanoic acid monomers linked together through ester bonds. This study demonstrates that cutin breakdown products can act as inducers of early plant immune responses, which underlying mechanisms of perception and potential use in agriculture warrant further investigation.
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