A role of prefrontal cortico-hypothalamic projections in wake promotion.

Ventromedial prefrontal cortex (vmPFC) processes many critical brain functions, such as decision-making, value-coding, thinking, and emotional arousal/recognition, but whether vmPFC plays a role in sleep-wake promotion circuitry is still unclear. Here, we find that photoactivation of dorsomedial hypothalamus (DMH)-projecting vmPFC neurons, their terminals, or their postsynaptic DMH neurons rapidly switches non-rapid eye movement (NREM) but not rapid eye movement sleep to wakefulness, which is blocked by photoinhibition of DMH outputs in lateral hypothalamus (LHs). Chemoactivation of DMH glutamatergic but not GABAergic neurons innervated by vmPFC promotes wakefulness and suppresses NREM sleep, whereas chemoinhibition of vmPFC projections in DMH produces opposite effects. DMH-projecting vmPFC neurons are inhibited during NREM sleep and activated during wakefulness. Thus, vmPFC neurons innervating DMH likely represent the first identified set of cerebral cortical neurons for promotion of physiological wakefulness and suppression of NREM sleep.

Simultaneous Electrophysiology and Imaging Reveal Changes in Lipid Membrane Thickness and Tension upon Uptake of Amphiphilic Gold Nanoparticles.

Amphiphilic gold core nanoparticles (AmNPs) striped with hydrophilic 11-mercapto-1-undecanesulfonate (MUS) and hydrophobic 1-octanethiol (OT) ligands are promising candidates for drug carriers that passively and nondisruptively enter cells. Yet, how they interact with cellular membranes is still only partially understood. Herein, we use electrophysiology and imaging to carefully assess changes in droplet interface bilayer lipid membranes (DIBs) incurred by striped AmNPs added via microinjection. We find that AmNPs spontaneously reduce the steady-state specific capacitance and contact angle of phosphatidylcholine DIBs by amounts dependent on the final NP concentration. These reductions, which are greater for NPs with a higher % OT ligands and membranes containing unsaturated lipids but negligible for MUS-only-coated NPs, reveal that AmNPs passively embed in the interior of the bilayer where they increase membrane thickness and lateral tension through disruption of lipid packing. These results demonstrate the enhanced evaluation of nano-bio interactions possible via electrophysiology and imaging of DIBs.

miRNA-126a-3p participates in hippocampal memory via alzheimer's disease-related proteins.

Memory formation and consolidation necessitate gene expression and new protein synthesis. MicroRNAs (miRNAs), a family of small noncoding RNAs that inhibit target gene mRNA expression, are involved in new memory formation. In this study, elevated miR-126a-3p (miR-126) levels were found to contribute to the consolidation of contextual fear memory. Using different commonly mined algorithms and luciferase reporter assay, we found two Alzheimer's disease (AD)-related proteins, namely EFHD2 and BACE1, but not ADAM9, were the targets downregulated by miR-126 after CFC training. Moreover, we indicated that upregulated miR-126 could promote the formation of contextual fear memory by modulating its target EFHD2. Finally, we demonstrated that miR-126 overexpression in dentate gyrus of hippocampus could reduce Aß plaque area and neuroinflammation, as well as rescue the hippocampal memory deficits in APP/PS1 mice. This study adds to the growing body of evidence for the role of miRNAs in memory formation and demonstrates the implication of EFHD2 protein regulated by miR-126 in the adult brain.

Dysregulation of non-coding RNAs mediates cisplatin resistance in hepatocellular carcinoma and therapeutic strategies.

Hepatocellular carcinoma (HCC) is the fourth major contributor to cancer-related deaths worldwide, and patients mostly have poor prognosis. Although several drugs have been approved for the treatment of HCC, cisplatin (CDDP) is still applied in treatment of HCC as a classical chemotherapeutic drug. Unfortunately, the emergence of CDDP resistance has caused HCC patients to exhibit poor drug response. How to mitigate or even reverse CDDP resistance is an urgent clinical issue to be solved. Because of critical roles in biological functional processes and disease developments, non-coding RNAs (ncRNAs) have been extensively studied in HCC in recent years. Importantly, ncRNAs have also been demonstrated to be involved in the development of HCC to CDDP resistance process. Therefore, this review highlighted the regulatory roles of ncRNAs in CDDP resistance of HCC, elucidated the multiple potential mechanisms by which HCC develops CDDP resistance, and attempted to propose multiple drug delivery systems to alleviate CDDP resistance. Recently, ncRNA-based therapy may be a feasible strategy to alleviate CDDP resistance in HCC. Meanwhile, nanoparticles can overcome the deficiencies in ncRNA-based therapy and make it possible to reverse tumor drug resistance. The combined use of these strategies provides clues for reversing CDDP resistance and overcoming the poor prognosis of HCC.

Layering of bidisperse charged nanoparticles in sedimentation.

Bidisperse mixtures of charged nanoparticles form separate layers upon centrifugation as a result of minimization of the system's free energy in sedimentation-diffusion equilibrium. Different factors were investigated experimentally for their effects on the layering, and are supported by theoretical calculations of the full sedimentation profiles. Surprisingly, lighter/smaller nanoparticles can even sink below heavier/larger ones when the particle surface charge is carefully tuned. This study provides deeper insights into the control of layering in polydisperse particle mixtures during sedimentation.

Binary Colloidal Nanoparticles with a Large Size Ratio in Analytical Ultracentrifugation.

Sedimenting colloidal particles may feel a surprisingly strong buoyancy in a mixture with other particles of a considerably larger size. In this paper we investigated the buoyancy of colloidal particles in a concentrated binary suspension in situ in a centrifugal field. After dispersing two different fluorescence-labeled silica nanoparticles with a large size ratio (90 nm and 30 nm, size ratio: 3) in a refractive index matching solvent, we used a multi-wavelength analytical ultracentrifuge to measure the concentration gradients of both particles in situ. The concentration of the 90 nm silica nanoparticles was used to calculate the effective solvent density for the 30 nm silica nanoparticles. The exponential Boltzmann equation for the sedimentation-diffusion equilibrium with locally varying effective solvent density was then used to theoretically predict the concentration gradient of 30 nm silica nanoparticles, which describes the experimental results very well. This finding proves the validity of effective buoyancy in colloidal mixtures and provides a good model to study sedimenting polydisperse colloids.

miR-151-5p modulates APH1a expression to participate in contextual fear memory formation.

Long-term memory formation requires gene expression and new protein synthesis. MicroRNAs (miRNAs), a family of small non-coding RNAs that inhibit target gene mRNA expression, are involved in new memory formation. In this study, elevated miR-151-5p (miR-151) levels were found to be responsible for hippocampal contextual fear memory formation. Using a luciferase reporter assay, we demonstrated that miR-151 targets APH1a, a protein that has been identified as a key factor in γ-secretase activity, namely APH1a. Blocking miR-151 can upregulate APH1a protein levels and subsequently impair hippocampal fear memory formation. These results indicate that miR-151 is involved in hippocampal contextual fear memory by inhibiting APH1a protein expression. This work provides novel evidence for the role of miRNAs in memory formation and demonstrates the implication of APH1a protein in miRNA processing in the adult brain.

miR-181a Participates in Contextual Fear Memory Formation Via Activating mTOR Signaling Pathway.

Long-term memory formation has been proven to require gene expression and new protein synthesis. MicroRNAs (miRNAs), as an endogenous small non-coding RNAs, inhibit the expression of their mRNA targets, through which involve in new memory formation. In this study, elevated miR-181a levels were found to be responsible for hippocampal contextual fear memory consolidation. Using a luciferase reporter assay, we indicated that miR-181a targets 2 upstream molecules of mTOR pathway, namely, PRKAA1 and REDD1. Upregulated miR-181a can downregulate the PRKAA1 and REDD1 protein levels and promote mTOR activity to facilitate hippocampal fear memory consolidation. These results indicate that miR-181a is involved in hippocampal contextual fear memory by activating the mTOR signaling pathway. This work provides a novel evidence for the role of miRNAs in memory formation and demonstrates the implication of mTOR signaling pathway in miRNA processing in the adult brain.

HDAC7 Ubiquitination by the E3 Ligase CBX4 Is Involved in Contextual Fear Conditioning Memory Formation.

Histone acetylation, an epigenetic modification, plays an important role in long-term memory formation. Recently, histone deacetylase (HDAC) inhibitors were demonstrated to promote memory formation, which raises the intriguing possibility that they may be used to rescue memory deficits. However, additional research is necessary to clarify the roles of individual HDACs in memory. In this study, we demonstrated that HDAC7, within the dorsal hippocampus of C57BL6J mice, had a late and persistent decrease after contextual fear conditioning (CFC) training (4-24 h), which was involved in long-term CFC memory formation. We also showed that HDAC7 decreased via ubiquitin-dependent degradation. CBX4 was one of the HDAC7 E3 ligases involved in this process. Nur77, as one of the target genes of HDAC7, increased 6-24 h after CFC training and, accordingly, modulated the formation of CFC memory. Finally, HDAC7 was involved in the formation of other hippocampal-dependent memories, including the Morris water maze and object location test. The current findings facilitate an understanding of the molecular and cellular mechanisms of HDAC7 in the regulation of hippocampal-dependent memory.SIGNIFICANCE STATEMENT The current findings demonstrated the effects of histone deacetylase 7 (HDAC7) on hippocampal-dependent memories. Moreover, we determined the mechanism of decreased HDAC7 in contextual fear conditioning (CFC) through ubiquitin-dependent protein degradation. We also verified that CBX4 was one of the HDAC7 E3 ligases. Finally, we demonstrated that Nur77, as one of the important targets for HDAC7, was involved in CFC memory formation. All of these proteins, including HDAC7, CBX4, and Nur77, could be potential therapeutic targets for preventing memory deficits in aging and neurological diseases.

Syntaxin 8 modulates the post-synthetic trafficking of the TrkA receptor and inflammatory pain transmission.

Nerve growth factor (NGF) promotes the survival, maintenance, and neurite outgrowth of sensory and sympathetic neurons, and the effects are mediated by TrkA receptor signaling. Thus, the cell surface location of the TrkA receptor is crucial for NGF-mediated functions. However, the regulatory mechanism underlying TrkA cell surface levels remains incompletely understood. In this study, we identified syntaxin 8 (STX8), a Q-SNARE protein, as a novel TrkA-binding protein. Overexpression and knockdown studies showed that STX8 facilitates TrkA transport from the Golgi to the plasma membrane and regulates the surface levels of TrkA but not TrkB receptors. Furthermore, STX8 modulates downstream NGF-induced TrkA signaling and, consequently, the survival of NGF-dependent dorsal root ganglia neurons. Finally, knockdown of STX8 in rat dorsal root ganglia by recombinant adeno-associated virus serotype 6-mediated RNA interference led to analgesic effects on formalin-induced inflammatory pain. These findings demonstrate that STX8 is a modulator of TrkA cell surface levels and biological functions.

Phosphorylation of cofilin regulates extinction of conditioned aversive memory via AMPAR trafficking.

Actin dynamics provide an important mechanism for the modification of synaptic plasticity, which is regulated by the actin depolymerizing factor (ADF)/cofilin. However, the role of cofilin regulated actin dynamics in memory extinction process is still unclear. Here, we observed that extinction of conditioned taste aversive (CTA) memory led to temporally enhanced ADF/cofilin activity in the infralimbic cortex (IrL) of the rats. Moreover, temporally elevating ADF/cofilin activity in the IrL could accelerate CTA memory extinction by facilitating AMPAR synaptic surface recruitment, whereas inhibition of ADF/cofilin activity abolished AMPAR synaptic surface trafficking and impaired memory extinction. Finally, we observed that ADF/cofilin-regulated synaptic plasticity was not directly coupled to morphological changes of postsynaptic spines. These findings may help us understand the role of ADF/cofilin-regulated actin dynamics in memory extinction and suggest that appropriate manipulating ADF/cofilin activity might be a suitable way for therapeutic treatment of memory disorders.

Transcriptome profiling analysis of the mechanisms underlying the BDNF Val66Met polymorphism induced dysfunctions of the central nervous system.

Brain-derived neurotrophic factor (BDNF) Val66Met polymorphism affects postnatal behaviors and is associated with a variety of neuropsychiatric disorders. However, the mechanisms underlying the BDNF(Met) variant induced dysfunctions of the central nervous system remain obscure. In order to identify the candidate genes and pathways responsible for the dysfunctions associated with this BDNF variation, we analyzed the expression of genes in the hippocampus, prefrontal cortex, and amygdala of the BDNF(Met) variant mice in comparison with the wild-type mice using Illumina bead microarray. Transcriptome profiling analysis revealed region-distinctive and gene-dose dependent changes of gene expression associated with the BDNF(Met) variant. BDNF(Met) variant mice exhibited altered expression of genes associated with translational machinery, neuronal plasticity and mitochondrial function based on the gene ontology (GO) annotation. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis revealed that the chemokine, cell adhesion, ubiquitin-proteosome and wnt signaling pathways were altered in the BDNF(Met) variant mice brain. Finally, the CX3CL1/CX3CR1 signaling was identified to be impaired in the hippocampus and microinjection of CX3CL1 into the hippocampus could rescue the hippocampal dependent memory deficits in BDNF(Met/Met) mice, indicating that CX3CL1 may be an effective treatment option for memory disorders in humans with this genetic BDNF variation. These findings will help us further understanding the molecular mechanisms involved in the BDNF(Met) associated behavior and neuroanatomy alternations.

Amino Acids and Their Biological Derivatives Modulate Protein-Protein Interactions in an Additive Way.

Protein-protein interactions (PPIs) differ when measured in test tubes and cells due to the complexity of the intracellular environment. Free amino acids (AAs) and their derivatives constitute a significant fraction of the intracellular volume and mass. Recently, we have found that AAs have a generic property of rendering protein dispersions more stable by reducing the net attractive part of PPIs. Here, we study the effects on PPIs of different AA derivatives, AA mixtures, and short peptides. We find that all the tested AA derivatives modulate PPIs in solution as effectively as AAs. Furthermore, we show that the modulation effect is additive when AAs form mixtures or are bound into short peptides. Therefore, this study demonstrates the additive effects of a class of small molecules (i.e., AAs and their biological derivatives) on PPIs and provides insights into rationally designing biocompatible molecules for stabilizing protein interactions and consequently tuning protein functions.

Evolution Pattern in Bruised Tissue of 'Red Delicious' Apple.

The study of apple damage mechanisms is key to improving post-harvest apple treatment techniques, and the evolution pattern of damaged tissue is fundamental to the study of apple damage mechanisms. In the study, 'Red Delicious' apples were used to explore the relationship between damage and time. A cell death zone was found in the pulp of the damaged tissue after the apple had been bruised. The tissue damage was centered in the cell death zone and developed laterally, with the width of the damage increasing with injury time. The extent of tissue damage in the core and pericarpal directions varied. About 60% of the damaged tissue developed in the core direction and 40% in the pericarpal direction, and the damage ratios in both directions remained consistent throughout the injury. The depth of damage and the rate of damage were influenced by the impact force size and the difference in the size of the damaged part of the apple, but the damage development pattern was independent of the impact force size and the difference in the damaged part. The maximum damage rate was reached at about 30 min, and the depth of damage was stabilized at about 72 min. By studying the evolution pattern of the damaged tissue of the bruised 'Red Delicious' apple, it provides the research idea and theoretical basis for enhancing the prediction accuracy and robustness of early stage damage in apples.

Ligand concentration determines antiviral efficacy of silica multivalent nanoparticles.

We have learned from the recent COVID-19 pandemic that the emergence of a new virus can quickly become a global health burden and kill millions of lives. Antiviral drugs are essential in our fight against viral diseases, but most of them are virus-specific and are prone to viral mutations. We have developed broad-spectrum antivirals based on multivalent nanoparticles grafted with ligands that mimic the target of viral attachment ligands (VALs). We have shown that when the ligand has a sufficiently long hydrophobic tail, the inhibition mechanism switches from reversible (virustatic) to irreversible (virucidal). Here, we investigate further how ligand density and particle size affect antiviral efficacy, both in terms of half-inhibitory concentration (IC50) and of reversible vs irreversible mechanism. We designed antiviral silica nanoparticles modified with 11-mercaptoundecane-1-sulfonic acid (MUS), a ligand that mimics heparan sulfate proteoglycans (HSPG) and we showed that these nanoparticles can be synthesized with different sizes (4-200 nm) and ligand grafting densities (0.59-10.70 /nm2). By testing these particles against herpes simplex virus type 2 (HSV-2), we show that within the size and density ranges studied, the antiviral IC50 is determined solely by equivalent ligand concentration. The nanoparticles are found to be virucidal at all sizes and densities studied.

Bistable memory devices with lower threshold voltage by extending the molecular alkyl-chain length.

Three organic small molecules with alkyl chains of different lengths based on an azobenzene scaffold were designed and synthesized. The indium-tin oxide (ITO)-Azo-Al sandwich memory devices showed write-once-read-many-times (WORM) characteristics. The switch threshold voltage of Azo-based memory devices significantly decreased as the end-capping alkyl chain extends, which is totally consistent with the AFM and X-ray diffraction results that the thin films showed smoother morphologies and closer intermolecular packing with the molecular alkyl-chain length prolonging. These results demonstrated that variation in the alkyl-chain length at the end of the conjugated molecules is a powerful strategy for tuning film microstructure and intermolecular packing to enable high performance of the fabricated sandwiched devices.

Comparative studies on chemical parameters and antioxidant properties of stipes and caps of shiitake mushroom as affected by different drying methods.

BACKGROUND: Shiitake, the second most cultivated mushroom, is famous for its high nutritional value and medicinal properties. In this study, various chemical parameters and antioxidant properties of caps and stipes of shiitake mushroom dried by different methods (freeze-drying, shade drying and hot air drying) were comparatively investigated by spectrophotometric assays, high-performance liquid chromatography, 1,1'-diphenyl-2-picrylhydrazyl assay, ferric reducing power assay and lipid peroxidation inhibition assay. RESULTS: The contents of amino acids, neutral sugar and total phenolics in stipes were higher than those in caps of shiitake, while caps showed advantages in terms of their contents of protein and eritadenine. The chemical parameters and antioxidant activities of shiitake were significantly affected by the drying method used. CONCLUSION: The contents of total phenolics, amino acids and neutral sugar in stipes were higher than those in caps of shiitake, which suggested that stipes were more nutritional than caps in some respects. Hot air drying at 50 °C resulted in high total phenolic, amino acid, uronic acid and neutral sugar contents and antioxidant activities, which could be useful for the application of shiitake and related products in the food industry.

Chromatin Remodeling Factor SMARCA5 is Essential for Hippocampal Memory Maintenance via Metabolic Pathways in Mice.

Gene transcription and new protein synthesis regulated by epigenetics play integral roles in the formation of new memories. However, as an important part of epigenetics, the function of chromatin remodeling in learning and memory has been less studied. Here, we showed that SMARCA5 (SWI/SNF related, matrix-associated, actin-dependent regulator of chromatin, subfamily A, member 5), a critical chromatin remodeler, was responsible for hippocampus-dependent memory maintenance and neurogenesis. Using proteomics analysis, we found protein expression changes in the hippocampal dentate gyrus (DG) after the knockdown of SMARCA5 during contextual fear conditioning (CFC) memory maintenance in mice. Moreover, SMARCA5 was revealed to participate in CFC memory maintenance via modulating the proteins of metabolic pathways such as nucleoside diphosphate kinase-3 (NME3) and aminoacylase 1 (ACY1). This work is the first to describe the role of SMARCA5 in memory maintenance and to demonstrate the involvement of metabolic pathways regulated by SMARCA5 in learning and memory.

Self-association and gel formation during sedimentation of like-charged colloids.

Formation of superstructures from colloidal dispersion involves a continuous increase in particle concentration, resulting in increasingly more complicated interparticle interaction. At high particle concentration, the presence of the super-crowding effect, strong non-ideality in addition to significant light absorption and scattering makes particle analysis very difficult. Here we report quantitative molecular, microscopic and macroscopic experimental results on like-charged colloids with concentration up to 60 vol%, close to the densest possible packing of spheres. It is achieved by conducting sedimentation-diffusion-equilibrium analytical ultracentrifugation (SE-AUC) on a concentrated dispersion of colloidal silica nanoparticles in a refractive-index-matching solvent. Surprisingly, we observed the self-association and even colloidal gel formation of like-charged colloids at very high concentration. Further experiments indicate that the attraction force may be counter-ion mediated. These results represent an important step forward in understanding complicated interparticle interaction in extremely high concentration, which is vital for the controlled fabrication of colloidal superstructures.

Cryogenic electron tomography to determine thermodynamic quantities for nanoparticle dispersions.

Here we present a method to extract thermodynamic quantities for nanoparticle dispersions in solvents. The method is based on the study of tomograms obtained from cryogenic electron tomography (cryoET). The approach is demonstrated for gold nanoparticles (diameter < 5 nm). Tomograms are reconstructed from tilt-series 2D images. Once the three-dimensional (3D) coordinates for the centres of mass of all of the particles in the sample are determined, we calculate the pair distribution function g(r) and the potential of mean force U(r) without any assumption. Importantly, we show that further quantitative information from 3D tomograms is readily available as the spatial fluctuation in the particles' position can be efficiently determined. This in turn allows for the prompt derivation of the Kirkwood-Buff integrals with all their associated quantities such as the second virial coefficient. Finally, the structure factor and the agglomeration states of the particles are evaluated directly. These thermodynamic quantities provide key insights into the dispersion properties of the particles. The method works well both for dispersed systems containing isolated particles and for systems with varying degrees of agglomerations.