Search

The sleep–wake patterns and nocturnal activity of diurnal birds have been little studied. Here, we analysed, by chance, those behaviours for free-living Eurasian Blue Tits (Cyanistes caeruleus, Linnaeus, 1758) roosting in nest boxes equipped with motion sensor-triggered Internet Protocol (IP) cameras. By monitoring individual birds over six sessions for more than one hundred nights each session, we found repetitive activity patterns during the night as well as a correlation between daylength and roosting times. Using the same method, we found the roosting behaviour of Eurasian Blue Tits (Cyanistes caeruleus, Linnaeus, 1758) to be comparable to that of Great Tits (Parus major, Linnaeus, 1758) and Common Starlings (Sturnus vulgaris, Linnaeus, 1758) in nest boxes in the same structure. These data, which we showed can be collected relatively easily and inexpensively, suggest that in rural areas the sleep–wake behaviours of free-living birds are mainly determined by the circadian rhythm associated with natural light.

Barttin is the accessory subunit of the human ClC-K chloride channels, which are expressed in both the kidney and inner ear. Barttin promotes trafficking of the complex it forms with ClC-K to the plasma membrane and is involved in activating this channel. Barttin undergoes post-translational palmitoylation that is essential for its functions, but the enzyme(s) catalyzing this post-translational modification is unknown. Here, we identified zinc finger DHHC-type containing 7 (DHHC7) protein as an important barttin palmitoyl acyltransferase, whose depletion affected barttin palmitoylation and ClC-K-barttin channel activation. We investigated the functional role of barttin palmitoylation in vivo in Zdhhc7(−/−) mice. Although palmitoylation of barttin in kidneys of Zdhhc7(−/−) animals was significantly decreased, it did not pathologically alter kidney structure and functions under physiological conditions. However, when Zdhhc7(−/−) mice were fed a low-salt diet, they developed hyponatremia and mild metabolic alkalosis, symptoms characteristic of human Bartter syndrome (BS) type IV. Of note, we also observed decreased palmitoylation of the disease-causing R8L barttin variant associated with human BS type IV. Our results indicate that dysregulated DHHC7-mediated barttin palmitoylation appears to play an important role in chloride channel dysfunction in certain BS variants, suggesting that targeting DHHC7 activity may offer a potential therapeutic strategy for reducing hypertension.

Background The number of studies on gender differences in psychomotor performance and sleepiness is small and the results are contradictory. The aim of this study was to assess the changes in psychomotor performance, due to 24 h of sleep deprivation in young women and men. Participants Eighty-nine students (49 women and 40 men) took part in the study. Participants were randomized into two groups: experimental (sleep deprived) and control (non-sleep deprived). Methods The research was carried out using computer-based tests of the Vienna Test System (COG, DT, WAFF) and pupillography (F2D Fit-For-Duty). Results There were no statistically significant effects of the main genders and groups on sleepiness measured by the pupillography. There was no deterioration in the results after deprivation among women and men in the COG test. Changes were noted in the DT and WAFF tests, and their size depended on the test. The number of false responses in psychomotor test was higher in women after sleep deprivation. Conclusion One night of sleep deprivation may not have been a negative enough stimulus for young, healthy women and men to reveal gender differences in psychomotor tests. Low sleep levels can lead to low productivity at work and accidents due to reduced vigilance. Insufficient sleep in the long term can lead to poor health, resulting in hypertension, obesity and depression.

Synopsis image The lack of an effective treatment for ALS is calling for the development of novel therapeutic strategies. By using hiPSC���derived motoneurons and focusing on synapse���related processes, we provide new molecular targets rescuing the degenerative processes and neuronal loss in ALS. Human C9orf72���mutant motoneurons are characterized by reduced expression of synaptic gene, progressive loss of CREB activity and synapse loss. Similar alterations are observed also in motoneurons harboring TBK1 pathogenic mutations, and in primary neurons upon overexpression of poly(GA) aggregates. The K+ channel blockers Apamin and XE991 revert the CREB���dependent loss of synaptic contacts and rescue the degenerative phenotypes of ALS motoneurons., publishedVersion

The small GTPase Cdc42 exists in the form of two alternatively spliced variants that are modified by hydrophobic chains: the ubiquitously expressed Cdc42-prenyl and a brain-specific isoform that can be palmitoylated, Cdc42-palm. Our previous work demonstrated that Cdc42-palm can be palmitoylated at two cysteine residues, Cys188 and Cys189, while Cys188 can also be prenylated. We showed that palmitoylation of Cys188 is essential for the plasma membrane localization of Cdc42-palm and is critically involved in Cdc42-mediated regulation of gene transcription and neuronal morphology. However, the abundance and regulation of this modification was not investigated. In the present study, we found that only a minor fraction of Cdc42 undergoes monopalmitoylation in neuroblastoma cells and in hippocampal neurons. In addition, we identified DHHC5 as one of the major palmitoyl acyltransferases that could physically interact with Cdc42-palm. We demonstrate that overexpression of dominant negative DHHC5 mutant decreased palmitoylation and plasma membrane localization of Cdc42-palm. In addition, knockdown of DHHC5 significantly reduced Cdc42-palm palmitoylation, leading to a decrease of Cdc42-mediated gene transcription and spine formation in hippocampal neurons. We also found that the expression of DHHC5 in the brain is developmentally regulated. Taken together, these findings suggest that DHHC5-mediated palmitoylation of Cdc42 represents an important mechanism for the regulation of Cdc42 functions in hippocampus.

Ageing provokes a plethora of molecular, cellular and physiological deteriorations, including heart failure, neurodegeneration, metabolic maladaptation, telomere attrition and hair loss. Interestingly, on the molecular level, the capacity to induce autophagy, a cellular recycling and cleaning process, declines with age across a large spectrum of model organisms and is thought to be responsible for a subset of age-induced changes. Here, we show that a 6-month administration of the natural autophagy inducer spermidine in the drinking water to aged mice is sufficient to significantly attenuate distinct age-associated phenotypes. These include modulation of brain glucose metabolism, suppression of distinct cardiac inflammation parameters, decreased number of pathological sights in kidney and liver and decrease of age-induced hair loss. Interestingly, spermidine-mediated age protection was associated with decreased telomere attrition, arguing in favour of a novel cellular mechanism behind the anti-ageing effects of spermidine administration. Supplementary Information The online version contains supplementary material available at 10.1007/s11357-020-00310-0.

Rabanal-Ruiz and Byron et al. present a novel mechanism of nutrient signaling that identifies FAs as key cellular hubs that coordinate growth factor signaling and amino acid input into the cell and are required for efficient downstream activation of mTORC1., The mammalian target of rapamycin complex 1 (mTORC1) integrates mitogenic and stress signals to control growth and metabolism. Activation of mTORC1 by amino acids and growth factors involves recruitment of the complex to the lysosomal membrane and is further supported by lysosome distribution to the cell periphery. Here, we show that translocation of lysosomes toward the cell periphery brings mTORC1 into proximity with focal adhesions (FAs). We demonstrate that FAs constitute discrete plasma membrane hubs mediating growth factor signaling and amino acid input into the cell. FAs, as well as the translocation of lysosome-bound mTORC1 to their vicinity, contribute to both peripheral and intracellular mTORC1 activity. Conversely, lysosomal distribution to the cell periphery is dispensable for the activation of mTORC1 constitutively targeted to FAs. This study advances our understanding of spatial mTORC1 regulation by demonstrating that the localization of mTORC1 to FAs is both necessary and sufficient for its activation by growth-promoting stimuli.

Aging is associated with functional alterations of synapses thought to contribute to age-dependent memory impairment (AMI). While therapeutic avenues to protect from AMI are largely elusive, supplementation of spermidine, a polyamine normally declining with age, has been shown to restore defective proteostasis and to protect from AMI in Drosophila. Here we demonstrate that dietary spermidine protects from age-related synaptic alterations at hippocampal mossy fiber (MF)-CA3 synapses and prevents the aging-induced loss of neuronal mitochondria. Dietary spermidine rescued age-dependent decreases in synaptic vesicle density and largely restored defective presynaptic MF-CA3 long-term potentiation (LTP) at MF-CA3 synapses (MF-CA3) in aged animals. In contrast, spermidine failed to protect CA3-CA1 hippocampal synapses characterized by postsynaptic LTP from age-related changes in function and morphology. Our data demonstrate that dietary spermidine attenuates age-associated deterioration of MF-CA3 synaptic transmission and plasticity. These findings provide a physiological and molecular basis for the future therapeutic usage of spermidine.

Background The number of studies on gender differences in psychomotor performance and sleepiness is small and the results are contradictory. The aim of this study was to assess the changes in psychomotor performance, due to 24 h of sleep deprivation in young women and men. Participants Eighty-nine students (49 women and 40 men) took part in the study. Participants were randomized into two groups: experimental (sleep deprived) and control (non-sleep deprived). Methods The research was carried out using computer-based tests of the Vienna Test System (COG, DT, WAFF) and pupillography (F2D Fit-For-Duty). Results There were no statistically significant effects of the main genders and groups on sleepiness measured by the pupillography. There was no deterioration in the results after deprivation among women and men in the COG test. Changes were noted in the DT and WAFF tests, and their size depended on the test. The number of false responses in psychomotor test was higher in women after sleep deprivation. Conclusion One night of sleep deprivation may not have been a negative enough stimulus for young, healthy women and men to reveal gender differences in psychomotor tests. Low sleep levels can lead to low productivity at work and accidents due to reduced vigilance. Insufficient sleep in the long term can lead to poor health, resulting in hypertension, obesity and depression.

The plasma membrane is a highly compartmentalised organelle containing specialised lipid microdomains or lipid rafts that enable the spatial regulation of signal transduction. Lipid microdomains are enriched in sphingolipids and cholesterol that are arranged in a highly ordered state. Functionally, they contribute to a lesser fluidity compared to the surrounding membrane. Besides their unique lipid composition, these domains are characterised by the accumulation of various signalling molecules, including G protein-coupled receptors (GPCRs) and its downstream effectors. In this way lipid microdomains can integrate a plethora of signalling cascades and thereby modulate the functions of e.g. GPCRs. Here, we provide a short overview about the role of lipid microdomains in the distribution and signalling of GPCRs with particular focus on serotonin receptors. Since recent investigations dealing with lipid microdomain functions revealed the participation of these membrane domains in various pathophysiological processes, we also discuss a possible link between lipid microdomains and serotonin receptor functions in the pathogenesis of depression.

Cdc42 (cell division cycle 42) is a member of the Rho GTPase family which regulates a variety of cellular activities by controlling actin cytoskeleton and gene expression. Cdc42 is expressed in the form of two splice variants. The canonical Cdc42 isoform is prenylated (Cdc42-prenyl), whereas the brainspecific isoform can be palmitoylated (Cdc42-palm). In the present study we have demonstrated palmitoylation of endogenous Cdc42 in rodent and human brains and identified Cys188 and Cys189 as acylation sites of Cdc42-palm. Moreover, we have shown that Cys188 can also be prenylated. Analysis of acylation-deficient mutants revealed that lipidation of Cys188 is essential for proper membrane binding of Cdc42-palm as well as for Cdc42-mediated regulation of gene transcription and induction of densely packed filopodia in neuroblastoma cells. We also found that Cdc42-prenyl is a dominant splice variant in a wide range of commonly used cell lines as well as in the cerebellum, whereas Cdc42-palm is the main Cdc42 isoform in hippocampus, where it is critically involved in the formation of dendritic filopodia and spines. Replacement of endogenous Cdc42 by its acylation-deficient mutants revealed the importance of Cdc42-palm lipidation for its morphogenic and synaptogenic effects in neurons. These findings demonstrate that dual lipidation of Cdc42-palm represents an important regulator of morphogenic signalling in hippocampal neurons.

Palmitoylation of cdc42 Promotes Spine Stabilization and Rescues Spine Density Deficit in a Mouse Model of 22q11.2 Deletion Syndrome. 22q11.2 deletion syndrome (22q11DS) is associated with learning and cognitive dysfunctions and a high risk of developing schizophrenia. It has become increasingly clear that dendritic spine plasticity is tightly linked to cognition. Thus, understanding how genes involved in cognitive disorders affect synaptic networks is a major challenge of modern biology. Several studies have pointed to a spine density deficit in 22q11DS transgenic mice models. Using the LgDel mouse model, we first quantified spine deficit at different stages using electron microscopy. Next we performed repetitive confocal imaging over several days on hippocampal organotypic cultures of LgDel mice. We show no imbalanced ratio between daily spine formation and spine elimination, but a decreased spine life expectancy. We corrected this impaired spine stabilization process by overexpressing ZDHHC8 palmitoyltransferase, whose gene belongs to the LgDel microdeletion. Overexpression of one of its substrates, the cdc42 brain-specific variant, under a constitutively active form (cdc42-palm-CA) led to the same result. Finally, we could rescue spine density in vivo, in adult LgDel mice, by injecting pups with a vector expressing cdc42-palm-CA. This study reveals a new role of ZDHHC8-cdc42-palm molecular pathway in postsynaptic structural plasticity and provides new evidence in favor of the dysconnectivity hypothesis for schizophrenia.

Human bone marrow-derived stromal cells (hBMSCs) derived from the adult organism hold great promise for diverse settings in regenerative medicine. Therefore a more complete understanding of hBMSC biology to fully exploit the cells’ potential for clinical settings is important. The protein CD24 has been reported to be involved in a diverse range of processes such as cancer, adaptive immunity, inflammation, and autoimmune diseases in other cell types. Its expression in hBMSCs, which has not yet been analyzed, may add an important aspect in the understanding of hBMSC biology. The present study therefore analyzes the expression, regulation, and functional implication of the surface protein CD24 in hBMSCs. Methods used are stimulation studies with TGF beta as well as shRNA-mediated knockdown and overexpression of CD24 followed by microarray, immunocytochemistry, and flow cytometric analyses. To our knowledge, we demonstrate for the first time that the expression of CD24 is an inherent property of hBMSCs. Importantly, the data links the upregulation of CD24 to the adoption of a myofibroblast-like gene expression pattern in hBMSCs. We demonstrate that CD24 is an important modulator in transforming growth factor beta 3 (TGFβ3) signaling with a reciprocal regulatory relationship between these two proteins.

Background It is proven that in patients with endstage renal disease (ESRD) the prevalence of sleep disorders (insomnia, periodic leg movement and sleep apnea) is high. This fact may contribute to an impaired quality of life and to an increased risk for cardiovascular diseases. However, only few published data are available with regard to sleepdisordered breathing in long-term hemodialysed patients.

Serotonin (5-hydroxytrympamine or 5-HT) is one of the phylogenetically oldest neurotransmitters, and the serotonergic system is among the earliest developed neuronal systems. Serotonin is critically involved in regulating multiple physiological functions, acting via a heterogenic receptor family that includes G protein-coupled receptors and ligand-gated ion channels. Although serotonergic neurons comprise a widely distributed and complex network that targets nearly every brain structure, serotonin-mediated signalling is under strict temporal and spatial control. Imbalance in serotonergic signalling is implicated in many pathophysiological conditions, including schizophrenia, Alzheimer's disease, depression, and anxiety. In addition to its well-established role as a neurotransmitter, serotonin is involved in many aspects of neural development, including neurite outgrowth, somatic morphology regulation, growth cone motility, synaptogenesis, and control of dendritic spine shape and density. The morphogenic effects of serotonin are developmentally regulated, and serotonin availability during sensitive developmental stages can modulate the formation and functions of behaviourally relevant neuronal networks in adulthood. Here we provide an overview of the molecular mechanisms responsible for the morphogenic effects of serotonin elicited by its different receptors in neurons. We also discuss the role of serotonin receptor-mediated morphogenic signalling in the development and maintenance of pathophysiological conditions.

Serotonin (5-hydroxytryptamine or 5-HT) is an important neurotransmitter regulating a wide range of physiological and pathological functions via activation of heterogeneously expressed 5-HT receptors. The 5-HT7 receptor is one of the most recently described members of the 5-HT receptor family. Functionally, 5-HT7 receptor is associated with a number of physiological and pathological responses, including serotonin-induced phase shifting of the circadian rhythm, control of memory as well as locomotor and exploratory activity. A large body of evidence indicates involvement of the 5-HT7 receptor in anxiety and depression, and recent studies suggest that 5-HT7 receptor can be highly relevant for the treatment of major depressive disorders. The 5-HT7 receptor is coupled to the stimulatory Gs-protein, and receptor stimulation results in activation of adenylyl cyclase (AC) leading to a rise of cAMP concentration. In addition, this receptor is coupled to the G12-protein to activate small GTPases of the Rho family. This review focuses on molecular mechanisms responsible for the 5-HT7 receptor-mediated signaling. We provide detailed overview of signaling cascades controlled and regulated by the 5-HT7 receptor and discuss the functional impact of 5-HT7 receptor for the regulation of different cellular and subcellular processes.

The purpose of this study was to examine, on the basis of masticatory performance (MP), total muscle work (TMW), and range of movement (RoM), whether reduction of the profile of the cusps results in loss of the biomechanical effectiveness of chewing by healthy dentate patients.Twenty healthy patients (10 female, mean age: 24.1 ± 1.2 years) chewed standardized silicone particles, performing 15 masticatory cycles. Three experimental conditions were investigated: chewing on (1) the natural dentition (ND), (2) splints with structured occlusal profiles simulating the patient's natural dentition (SS), and (3) splints with a plane surface (PS). The expectorated particles were analyzed by a validated scanning procedure. The size distribution of the particles was calculated with the Rosin-Rammler function and the mean particle sizes (X50) were determined for each experimental condition. The target variables of the experimental conditions were compared by repeated measures analysis of variance.X50 values calculated for MP differed significantly (P.002) between PS and SS, and between ND and SS. Conversely, no significant differences (P.05) were observed between SS and ND. Regarding muscle work the EMG activity of the masseter differed significantly (P.001) between the left and right sides, with higher values for the right (chewing) side. No significant differences (P.05) were observed for TMW and RoM under the three test conditions.The results confirm the biomechanical significance of structured occlusal surfaces during chewing of brittle test food by young dentate subjects.

Experimental evidence suggests that most members of class A G-protein coupled receptors (GPCRs) can form homomers and heteromers in addition to functioning as single monomers. In particular, serotonin (5-HT) receptors were shown to homodimerize and heterodimerize with other GPCRs, although the details and the physiological role of the oligomerization has not yet been fully elucidated. Here we used computational modeling of the 5-HT(1A) receptor monomer and dimer to predict residues important for dimerization. Based on these results, we carried out rationally designed site-directed mutagenesis. The ability of the mutants to dimerize was evaluated using different FRET-based approaches. The reduced levels of acceptor photobleaching-Forster resonance energy transfer (FRET) and the lower number of monomers participating in oligomers, as assessed by lux-FRET, confirmed the decreased ability of the mutants to dimerize and the involvement of the predicted contacts (Trp175(4.64), Tyr198(5.41), Arg151(4.40), and Arg152(4.41)) at the interface. This information was reintroduced as constraints for computational protein-protein docking to obtain a high-quality dimer model. Analysis of the refined model as well as molecular dynamics simulations of wild-type (WT) and mutant dimers revealed compensating interactions in dimers composed of WT and W175A mutant. This provides an explanation for the requirement of mutations of Trp175(4.64) in both homomers for disrupting dimerization. Our iterative computational-experimental study demonstrates that transmembrane domains TM4/TM5 can form an interaction interface in 5-HT(1A) receptor dimers and indicates that specific amino acid interactions maintain this interface. The mutants and the optimized model of the dimer structure may be used in functional studies of serotonin dimers.

The common neurotransmitter serotonin controls different aspects of early neuronal differentiation, although the underlying mechanisms are poorly understood. Here we report that activation of the serotonin 5-HT7receptor promotes synaptogenesis and enhances synaptic activity in hippocampal neurons at early postnatal stages. An analysis of Gα12-deficient mice reveals a critical role of G12-protein for 5-HT7receptor-mediated effects in neurons. In organotypic preparations from the hippocampus of juvenile mice, stimulation of 5-HT7R/G12signaling potentiates formation of dendritic spines, increases neuronal excitability, and modulates synaptic plasticity. In contrast, in older neuronal preparations, morphogenetic and synaptogenic effects of 5-HT7/G12signaling are abolished. Moreover, inhibition of 5-HT7receptor had no effect on synaptic plasticity in hippocampus of adult animals. Expression analysis reveals that the production of 5-HT7and Gα12-proteins in the hippocampus undergoes strong regulation with a pronounced transient increase during early postnatal stages. Thus, regulated expression of 5-HT7receptor and Gα12-protein may represent a molecular mechanism by which serotonin specifically modulates formation of initial neuronal networks during early postnatal development.

Regulation of neuronal morphology and activity-dependent synaptic modifications involves reorganization of the actin cytoskeleton. Dynamic changes of the actin cytoskeleton in many cell types are controlled by small GTPases of the Rho family, such as RhoA, Rac1 and Cdc42. As key regulators of both actin and microtubule cytoskeleton, Rho GTPases have also emerged as important regulators of dendrite and spine structural plasticity. Multiple studies suggest that Rac1 and Cdc42 are positive regulators promoting neurite outgrowth and growth cone protrusion, while the activation of RhoA induces stress fiber formation, leading to growth cone collapse and neurite retraction. This review focuses on recent advances in our understanding of the molecular mechanisms underlying physiological and pathological functions of Cdc42 in the nervous system. We also discuss application of different FRET-based biosensors as a powerful approach to examine the dynamics of Cdc42 activity in living cells.