Planar cell polarity proteins mediate ketamine-induced restoration of glutamatergic synapses in prefrontal cortical neurons in a mouse model for chronic stress.

Single administration of low-dose ketamine has both acute and sustained anti-depressant effects. Sustained effect is associated with restoration of glutamatergic synapses in medial prefrontal cortic (mFPC) neurons. Ketamine induced profound changes in a number of molecular pathways in a mouse model for chronic stress. Cell-cell communication analyses predicted that planar-cell-polarity (PCP) signaling was decreased after chronic administration of corticosterone but increased following ketamine administration in most of the excitatory neurons. Similar decrease of PCP signaling in excitatory neurons was predicted in dorsolateral prefrontal cortical (dl-PFC) neurons of patients with major depressive disorder (MDD). We showed that the basolateral amygdala (BLA)-projecting infralimbic prefrontal cortex (IL PFC) neurons regulate immobility time in the tail suspension test and food consumption. Conditionally knocking out Celsr2 and Celsr3 or Prickle2 in the BLA-projecting IL PFC neurons abolished ketamine-induced synapse restoration and behavioral remission. Therefore, PCP proteins in IL PFC-BLA neurons mediate synapse restoration induced by of low-dose ketamine.

Enhanced Biofilm Formation by Tetracycline in a Staphylococcus aureus Naturally Lacking ica Operon and atl.

Staphylococcus aureus is a major, widespread pathogen, and its biofilm-forming characteristics make it even more difficult to eliminate by biocides. Tetracycline (TCY) is a major broad-spectrum antibiotic, the residues of which can cause deleterious health impacts, and subinhibitory concentrations of TCY have the potential to increase biofilm formation in S. aureus. In this study, we showed how the biofilm formation of S. aureus 123786 is enhanced in the presence of TCY at specific subinhibitory concentrations. S. aureus 123786 used in this study was identified as Staphylococcal Cassette Chromosome mec III, sequence type239 and naturally lacking ica operon and atl gene. Two assays were performed to quantify the formation of S. aureus biofilm. In the crystal violet (CV) assay, the absorbance values of biofilm stained with CV at optical density (OD)540 nm increased after 8 and 16 hr of incubation when the concentration of TCY was 1/2 minimum inhibitory concentration (MIC), whereas at the concentration of 1/16 MIC, the absorbance values increased after 16 and 24 hr of incubation. In tetrazolium salt reduction assay, the absorbance value at OD490 nm of S. aureus 123786 biofilms mixed with 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium solution increased after 8 hr when the concentration of TCY was 1/4 MIC, which may be correlated with the higher proliferation and maturation of biofilm. In conclusion, the biofilm formation of S. aureus 123786 could be enhanced in the presence of TCY at specific subinhibitory concentrations.

Emerging roles of planar cell polarity proteins in glutamatergic synapse formation, maintenance and function in health and disease.

The local signaling mechanism which directly assembles and maintains glutamatergic synapses has not been well understood. Glutamatergic synapses are made of presynaptic and postsynaptic compartments with distinct sets of proteins. The planar cell polarity (PCP) pathway is highly conserved and responsible for establishing and maintaining the cell and tissue polarity along the tissue plane. The six core PCP proteins form antagonizing complexes within the cells and asymmetric intercellular complexes across neighboring cells which regulate cell-cell interactions during planar polarity signaling. Accumulating evidence suggests that the PCP proteins play essential roles in glutamatergic synapse assembly, maintenance and function in the brain. This review summarizes the key evidence that PCP proteins may be responsible for the formation and stability of the vast majority of the glutamatergic synapses in hippocampus and medial prefrontal cortex, the progress in understanding the mechanisms of how PCP proteins assemble and maintain glutamatergic synapses and initial insights on how disruption of the function of the PCP proteins can lead to neurodegenerative, neurodevelopmental and neuropsychiatric disorders. The PCP proteins may be the missing pieces of a long-standing puzzle and filling this gap of knowledge may provide the basis for understanding many unsolved questions in synapse biology.

The Fragile X Messenger Ribonucleoprotein 1 Participates in Axon Guidance Mediated by the Wnt/Planar Cell Polarity Pathway.

The Planar cell polarity (PCP) pathway is known to mediate the function of the Wnt proteins in growth cone guidance. Here, we show that the PCP pathway may directly influence local protein synthesis within the growth cones. We found that Fragile X Messenger Ribonucleoprotein 1 (FMRP) interacts with Fzd3. This interaction is negatively regulated by Wnt5a, which induces FMRP phosphorylation. Knocking down FMRP via electroporating shRNAs into the dorsal spinal cord lead to a randomization of anterior-posterior turning of post-crossing commissural axons, which could be rescued by a FMRP rescue construct. Using RNAscope, we found that some of the FMRP target mRNAs encoding PCP components, PRICKLE2 and Celsr2, as well as regulators of cytoskeletal dynamics and components of cytoskeleton, APC, Cfl1, Map1b, Tubb3 and Actb, are present in the commissural neuron growth cones. Our results suggest that PCP signaling may regulate growth cone guidance, at least in part, by regulating local protein synthesis in the growth cones through via an interaction between Frizzled3 and FMRP.

Corrigendum: First report on the rapid detection and identification of methicillin-resistant Staphylococcus aureus (MRSA) in viable but non-culturable (VBNC) under food storage conditions.

[This corrects the article DOI: 10.3389/fmicb.2020.615875.].

Image Observation Study on Improving the Effectiveness of Muscle Strength Training for Sprinters.

In order to solve the problem of improving the effectiveness of muscle strength training for sprinters, this paper presents a study using image observation technology. The main content of this technology research is to determine the experimental object and method according to the image observation and muscle characteristics. Through the data processing and other processes, it is concluded that the image observation technology has a high accuracy in the observation of muscle movement patterns. The experimental results show that when the relationship number r = 0.99, the average error of prediction is 0.09, and the image observation technology has a high accuracy in the observation of muscle movement. Conclusion. It is proved that the technical research of image observation is effective and accurate for improving the training of sports muscle strength of sprinters.

Molecular-level insights into the surface-induced assembly of functional bacterial amyloid.

Protein coating material is important in many technological fields. The interaction between carbon nanomaterial and protein is especially interesting since it makes the development of novel hybrid materials possible. Functional bacterial amyloid (FuBA) is promising as a coating material because of its desirable features, such as well-defined molecular structure, robustness against harsh conditions, and easily engineerable functionality. Here, we report the systematic assembly of the functional amyloid protein, CsgA, from Escherichia coli (E. coli) on graphite. We characterize the assemblies using scanning tunneling microscopy (STM) and show that CsgA forms assemblies according to systematic patterns, dictated by the graphite lattice. In addition, we show that graphite flakes induce the fibrillization of CsgA, in vitro, suggesting a surface-induced conformational change of CsgA facilitated by the graphite lattice. Using coarse-grained molecular dynamics simulations, we model the adhesion and lamellar formation of a CsgA-derived peptide and conclude that peptides are adsorbed both as monomers and smaller aggregates leading initially to unordered graphite-bound aggregates, which are followed by rearrangement into lamellar structures. Finally, we show that CsgA-derived peptides can be immobilized in very systematic assemblies and their molecular orientation can be tuned using a small chaperone-like molecule. Our findings have implications for the development of FuBA-based biosensors, catalysts, and other technologies requiring well-defined protein assemblies on graphite.

Inter-growth cone communication mediated by planar cell polarity pathway in axon guidance.

The emergence of exquisitely organized axonal projections is one of the greatest wonders of nervous system development. In addition to growing along stereotyped directions, axons join one another as they extend. It is well known that axonal growth cones recognize cell surface guidance cues on axons and either grow along the axons or away from the axons. However, it is less well understood whether and how the growth cones communicate with each other and, if so, what do these interactions mean. Recent studies from our lab provided direct evidence that the growth cones do interact with each other during axon pathfinding. And this interaction is regulated by highly regulated protein-protein interactions among components of the planar cell polarity pathway. The disruption of these interactions lead to guidance defects and disorganization of axons. We propose that this local inter-growth cone PCP-like signaling mechanism reinforces and increases the sensitivity of the growth cone response to shallow Wnt gradients to turn in a precise and organized fashion.

Rhenium-guanidine complex as photosensitizer: trigger HeLa cell apoptosis through death receptor-mediated, mitochondria-mediated, and cell cycle arrest pathways.

The growing evidence over the past few decades has indicated that the photodynamic antitumor activity of transition metal complexes, and Re(I) compounds are potential candidates for photodynamic therapy. This study reports the synthesis, characterization, and anti-tumor activity of three new Re(I)-guadinium complexes. Cytotoxicity tests reveal that complex Re1 increased cytotoxicity by 145-fold from IC50 > 180 µM in the dark to 1.3 ± 0.7 µM following 10 min of light irradiation (425 nm) in HeLa cells. Further, the mechanism by which Re1 induces apoptosis in the presence or absence of light irradiation was investigated, and results indicate that cell death was caused through different pathways. Upon irradiation, Re1 first accumulates on the cell membrane and interacts with death receptors to activate the extrinsic death receptor-mediated signaling pathway, and then is transported into the cell cytoplasm. Most of the intracellular Re1 locates within mitochondria, improving the reactive oxygen species level, and decreasing mitochondrial membrane potential and ATP levels, and inducing the activation of caspase-9 and, thus, apoptosis. Subsequently, the residual Re1 can translocate into the cell nucleus, and activates the p53 pathway, causing cell cycle arrest and eventually cell death.

Characterization of Axon Guidance Phenotypes in Wnt/PCP Mutant Mice.

Our lab showed that the Wnt family proteins can function as axon guidance molecules and the planar cell polarity (PCP) pathway mediates the function of Wnts in axon guidance. One of the key evidences was by identifying the axon guidance defects in knockout or conditional knockout animals. We utilized a variety of axon tracing and labeling techniques, including immunohistochemistry (IHC), DiI, BDA, and fluorescent reporters (GFP or tdTomato). These studies have primarily been conducted in spinal cord commissural axons, but have been applied to retinal ganglion cell axons, corticospinal tract axons, dopaminergic and serotonergic projections.

In Vitro Explant Assays and Cultures to Study PCP Signaling in Axon Guidance.

In vitro studies have provided valuable insights to the function and mechanisms in axon guidance. In this chapter, we will introduce the rodent "open-book" assay, pre- or postcrossing explant culture and the dissociated neuron culture. They have been used to discover mechanism which we have gone on to validate or will confirm using in vivo genetic approaches.

Biochemical and Cellular Assays to Study Mechanisms of PCP Signaling in Axon Guidance.

Understanding biochemical and cellular mechanisms of how PCP components regulate axon guidance is important for understanding brain development and may lead to new therapeutic approaches for neural repair. Meanwhile, axonal growth cones are a highly polarized structure and are a great experimental system. Therefore, some of these novel mechanisms we are uncovering for axon guidance may be applicable for PCP signaling in general. In this chapter, we introduce some of the techniques we used or developed: (1) protein localization and trafficking; (2) protein phosphorylation; and (3) protein-protein interactions in the same cell and across the two neighboring cells.

Mutation of the murine Prickle1 (R104Q) causes phenotypes analogous to human symptoms of epilepsy and autism.

Epilepsy and autism spectrum disorders (ASD) frequently show comorbidity, suggesting shared or overlapping neurobiological basis underlying these conditions. R104Q is the first mutation in the PRICKLE 1(PK1) gene that was discovered in human patients with progressive myoclonus epilepsy (PME). Subsequently, a number of mutations in the PK1 gene were shown to be associated with either epilepsy, autism, or both, as well as other developmental disorders. Using CRISPR-Cas9-mediated gene editing, we generated a PK1R104Q mouse line. The mutant mice showed reduced density of excitatory synapses in hippocampus and impaired interaction between PK1 and the repressor element 1(RE-1) silencing transcription factor (REST). They also displayed reduced seizure threshold, impaired social interaction, and cognitive functions. Taken together, the PK1R104Q mice display characteristic behavioral features similar to the key symptoms of epilepsy and ASD, providing a useful model for studying the molecular and neural circuit mechanisms underlying the comorbidity of epilepsy and ASD.

Prickle promotes the formation and maintenance of glutamatergic synapses by stabilizing the intercellular planar cell polarity complex.

Whether there exists a common signaling mechanism that assembles all glutamatergic synapses is unknown. We show here that knocking out Prickle1 and Prickle2 reduced the formation of the PSD-95­positive glutamatergic synapses in the hippocampus and medial prefrontal cortex in postnatal development by 70­80%. Prickle1 and Prickle2 double knockout in adulthood lead to the disassembly of 70 to 80% of the postsynaptic-density(PSD)-95­positive glutamatergic synapses. PSD-95­positive glutamatergic synapses in the hippocampus of Prickle2E8Q/E8Q mice were reduced by 50% at postnatal day 14. Prickle2 promotes synapse formation by antagonizing Vangl2 and stabilizing the intercellular complex of the planar cell polarity (PCP) components, whereas Prickle2 E8Q fails to do so. Coculture experiments show that the asymmetric PCP complexes can determine the presynaptic and postsynaptic polarity. In summary, the PCP components regulate the assembly and maintenance of a large number of glutamatergic synapses and specify the direction of synaptic transmission.

Measurement of the Total Lung Volume Using an Adjusted Single-Breath Helium Dilution Method in Patients With Obstructive Lung Disease.

Background: Whole-body plethysmography (WBP) is the gold standard for measuring lung volume, but its clinical application is limited as it requires expensive equipment and is not simple to use. Studies have shown that the single-breath helium dilution (SBHD) method, which is commonly used in clinical practice, significantly underestimates lung volume in patients with obstructive lung disease (OLD). By comparing the differences in lung volume measured using SBHD and WBP, we aimed to establish a correction equation for the SBHD method to determine the total lung volume in patients with OLD of different severities. Methods: From 628 patients with OLD simultaneously subjected to SBHD and WBP, 407 patients enrolled between January 2018 and November 2019 were in the training group and 221 enrolled between December 2019 and December 2020 were in the prospective verification cohort. The multiple linear regression equation was used for data in the training group to establish a correction equation for SBHD to determine the total lung volume, and this was validated in the prospective validation cohort. Results: There was a moderate positive correlation between total lung capacity (TLC) determined using the SBHD [TLC (SBHD)] and WBP methods [TLC (WBP)] (r = 0.701; P < 0.05), and the differences between TLC (SBHD) and TLC (WBP) (ΔTLC) were related to the severity of obstruction. As the severity of obstruction increased, the TLC was underestimated by the SBHD method. We established the following correction equation: TLC (adjusted SBHD) (L) = -0.669 + 0.756*TLC(SBHD)(L) - 0.047* F E V 1 F V C +0.039*height (cm)-0.009*weight(kg)(r2 = 0.753 and adjusted r2 = 0.751). Next, we validated this equation in the validation cohort. With the correction equation, no statistical difference was observed between TLC (adjusted SBHD) and TLC (WBP) among the obstruction degree groups (P > 0.05). Conclusions: The SBHD method is correlated with WBP to measure the total lung volume, but the SBHD method presents limitations in determining the total lung volume in patients with obstructive lung disease. Here, we established an effective and reliable correction equation in order to accurately assess the total lung volume of patients with OLD using the SBHD method.

Planar cell polarity signaling components are a direct target of ß-amyloid-associated degeneration of glutamatergic synapses.

The signaling pathway directly controlling the maintenance of adult glutamatergic synapses has not been well understood. Planar cell polarity (PCP) signaling components were recently shown to play essential roles in the formation of glutamatergic synapses. Here, we show that they are localized in the adult synapses and are essential for their maintenance. Synapse loss at early stages of Alzheimer's disease is thought to be induced by ß-amyloid (Aß) pathology. We found that oligomeric Aß binds to Celsr3 and assists Vangl2 in disassembling synapses. Moreover, a Wnt receptor and regulator of PCP signaling, Ryk, is also required for Aß-induced synapse loss. In the 5XFAD mouse model of Alzheimer's disease, Ryk conditional knockout or a function-blocking monoclonal Ryk antibody protected synapses and preserved cognitive function. We propose that tipping of the fine balance of Wnt/PCP signaling components in glutamatergic synapses may cause synapse degeneration in neurodegenerative disorders with Aß pathology.

Anti-fouling peptide functionalization of ultraflexible neural probes for long-term neural activity recordings in the brain.

Implantable neural probes constitute an essential tool for neuronal activity recordings in basic neuroscience and also hold great promise for the development of neuroprosthesis to restore lost motor or sensory functions of the body. However, conventional neural probes are susceptible to biofouling because of their physicochemical mismatch with neural tissues, resulting in signal degradation in chronic studies. Here, we describe an ultraflexible neural probe (uFNP) with anti-fouling zwitterionic peptide modification for long-term stable neural activity recordings. The anti-fouling zwitterionic peptide consists of two parts: negatively charged glutamic acid (E) and positively charged lysine (K) formed EKEKEK (EK) head to create a hydration layer that resists protein adsorption on the microelectrodes, and a fragment of laminin formed IKVAV tail to increase the adhesion of the microelectrodes to neuronal cells. We demonstrate that EK-IKVAV modified uFNPs can allow for stable neuronal activity recordings over 16 weeks. Immunohistological studies confirm that EK-IKVAV functionalized uFNPs could induce greatly reduced neuronal cell loss. Collectively, these results suggest that the anti-fouling zwitterionic peptide functionalization of uFNPs provide a promising route to construct biocompatible and stable neural interfaces.

Composition-dependent multivalency of peptide-peptide interactions revealed by tryptophan-scanning mutagenesis.

We have examined in this contribution the composition dependence of binding characteristics in peptide-peptide interactions between an oligopeptide octa-glycine and a series of tryptophan-containing octapeptides. The binding energy associated with tryptophan-glycine interactions manifests pronounced stepwise binding characteristics as the number of tryptophan increases from 0 to 8 in the octapeptides consisting only of glycine and can be attributed to mono-, di-, and tri-valent peptide-peptide interactions. At the same time, only weak fluctuations in binding energy were observed as the number of tryptophan increases from 2 to 7. Such distinctive nonlinearity of composition-dependent tryptophan-glycine binding energy characteristics due to continuously varying tryptophan compositions in the octapeptides could be considered as a reflection of combinatorial contributions due to the hydrogen bonds originated from the indole moieties of tryptophan with the main chains of octapeptide of glycine containing N-H and C=O moieties and the van der Waals interactions (including π-π and π-CH interactions) between peptides.

Targeting axon guidance cues for neural circuit repair after spinal cord injury.

At least two-thirds of spinal cord injury cases are anatomically incomplete, without complete spinal cord transection, although the initial injuries cause complete loss of sensory and motor functions. The malleability of neural circuits and networks allows varied extend of functional restoration in some individuals after successful rehabilitative training. However, in most cases, the efficiency and extent are both limited and uncertain, largely due to the many obstacles of repair. The restoration of function after anatomically incomplete injury is in part made possible by the growth of new axons or new axon branches through the spared spinal cord tissue and the new synaptic connections they make, either along the areas they grow through or in the areas they terminate. This review will discuss new progress on the understanding of the role of axon guidance molecules, particularly the Wnt family proteins, in spinal cord injury and how the knowledge and tools of axon guidance can be applied to increase the potential of recovery. These strategies, combined with others, such as neuroprotection and rehabilitation, may bring new promises. The recovery strategies for anatomically incomplete spinal cord injuries are relevant and may be applicable to traumatic brain injury and stroke.