Novel Cinnamaldehyde Derivatives Inhibit Peripheral Nerve Degeneration by Targeting Schwann Cells.

Peripheral nerve degeneration (PND) is a preparative process for peripheral nerve regeneration and is regulated by Schwann cells, a unique glial cell in the peripheral nervous system. Dysregulated PND induces irreversible peripheral neurodegenerative diseases (e.g., diabetic peripheral neuropathy). To develop novel synthetic drugs for these diseases, we synthesized a set of new cinnamaldehyde (CAH) derivatives and evaluated their activities in vitro, ex vivo, and in vivo. The 12 CAH derivatives had phenyl or naphthyl groups with different substitution patterns on either side of the α,ß-unsaturated ketone. Among them, 3f, which had a naphthaldehyde group, was the most potent at inhibiting PND in vitro, ex vivo, and in vivo. To assess their interactions with transient receptor potential cation channel subfamily A member 1 (TRPA1) as a target of CAH, molecular docking studies were performed. Hydrophobic interactions had the highest binding affinity. To evaluate the underlying pharmacological mechanism, we performed bioinformatics analysis of the effect of 3f on PND based on coding genes and miRNAs regulated by CAH, suggesting that 3f affects oxidative stress in Schwann cells. The results show 3f to be a potential lead compound for the development of novel synthetic drugs for the treatment of peripheral neurodegenerative diseases.

Investigation of the Hydrogen Sulfide Signaling Pathway in Schwann Cells during Peripheral Nerve Degeneration: Multi-Omics Approaches.

N-ethylmaleimide (NEM) inhibits peripheral nerve degeneration (PND) by targeting Schwann cells in a hydrogen sulfide (H2S)-pathway-dependent manner, but the underlying molecular and pharmacological mechanisms are unclear. We investigated the effect of NEM, an α,ß-unsaturated carboxyl compound, on H2S signaling in in vitro- and ex vivo-dedifferentiated Schwann cells using global proteomics (LC-MS) and transcriptomics (whole-genome and small RNA-sequencing (RNA-seq)) methods. The multi-omics analyses identified several genes and proteins related to oxidative stress, such as Sod1, Gnao1, Stx4, Hmox2, Srxn1, and Edn1. The responses to oxidative stress were transcriptionally regulated by several transcription factors, such as Atf3, Fos, Rela, and Smad2. In a functional enrichment analysis, cell cycle, oxidative stress, and lipid/cholesterol metabolism were enriched, implicating H2S signaling in Schwann cell dedifferentiation, proliferation, and myelination. NEM-induced changes in the H2S signaling pathway affect oxidative stress, lipid metabolism, and the cell cycle in Schwann cells. Therefore, regulation of the H2S signaling pathway by NEM during PND could prevent Schwann cell demyelination, dedifferentiation, and proliferation.

Protective and therapeutic effect of (S)-ginsenoside F1 on peripheral nerve degeneration targeting Schwann cells: a pharmaco-neuroanatomical approach.

Damaged peripheral nerves undergo peripheral neurodegenerative processes that are essential for the nerve regeneration. Peripheral neurodegenerative diseases, including diabetic peripheral neuropathy, are induced by irreversible nerve damage caused by abnormal peripheral nerve degeneration. However, until now, there have been no effective therapeutic treatments for these diseases. Ginsenosides are the most pharmacologically active compounds in Panax ginseng, and are being actively studied. Ginsenosides have a variety of effects, including neuroprotective, antioxidative, anti-cytotoxic, and anti-inflammatory effects. Here, we investigated the efficacy of 18 ginsenosides. We then tested the ability of the most effective ginsenoside, (S)-ginsenosides F1 (sF1), to inhibit peripheral neurodegenerative processes using mouse sciatic ex vivo culture, and several morphological and biochemical indicators. Our results suggest that sF1 could effectively protect Schwann cells against peripheral nerve degeneration.

Inhibition of transient receptor potential melastatin 7 (TRPM7) protects against Schwann cell trans-dedifferentiation and proliferation during Wallerian degeneration.

Irreversible peripheral neurodegenerative diseases such as diabetic peripheral neuropathy are becoming increasingly common due to rising rates of diabetes mellitus; however, no effective therapeutic treatments have been developed. One of main causes of irreversible peripheral neurodegenerative diseases is dysfunction in Schwann cells, which are neuroglia unique to the peripheral nervous system (PNS). Because homeostasis of calcium (Ca2+) and magnesium (Mg2+) is essential for Schwann cell dynamics, the regulation of these cations is important for controlling peripheral nerve degeneration and regeneration. Transient receptor potential melastatin 7 (TRPM7) is a non-selective ion (Ca2+ and Mg2+) channel that is expressed in Schwann cells. In the present study, we demonstrated in an ex vivo culture system that inhibition of TRPM7 during peripheral nerve degeneration (Wallerian degeneration) suppressed dedifferentiable or degenerative features (trans-dedifferentiation and proliferation) and conserved a differentiable feature of Schwann cells. Our results indicate that TRPM7 could be very useful as a molecular target for irreversible peripheral neurodegenerative diseases, facilitating discovery of new therapeutic methods for improving human health.

Penta-fluorophenol: a Smiles rearrangement-inspired cysteine-selective fluorescent probe for imaging of human glioblastoma.

Two of the most critical factors for the survival of glioblastoma (GBM) patients are precision diagnosis and the tracking of treatment progress. At the moment, various sophisticated and specific diagnostic procedures are being used, but there are relatively few simple diagnosis methods. This work introduces a sensing probe based on a turn-on type fluorescence response that can measure the cysteine (Cys) level, which is recognized as a new biomarker of GBM, in human-derived cells and within on-site human clinical biopsy samples. The Cys-initiated chemical reactions of the probe cause a significant fluorescence response with high selectivity, high sensitivity, a fast response time, and a two-photon excitable excitation pathway, which allows the imaging of GBM in both mouse models and human tissue samples. The probe can distinguish the GBM cells and disease sites in clinical samples from individual patients. Besides, the probe has no short or long-term toxicity and immune response. The present findings hold promise for application of the probe to a relatively simple and straightforward following of GBM at clinical sites.

Carvacrol effectively protects demyelination by suppressing transient receptor potential melastatin 7 (TRPM7) in Schwann cells.

Peripheral neurodegenerative processes are essential for regenerating damaged peripheral nerves mechanically or genetically. Abnormal neurodegenerative processes induce peripheral neurodegenerative diseases via irreversible nerve damage. Carvacrol, a major component in Origanum vulgare, possesses various effects on organisms, such as antibiotic, anti-inflammatory and cytoprotective effects; although transient receptor potential (TRP) ankyrin 1 (TRPA1), TRP canonical 1 (TRPC1), TRP melastatin M7 (TRPM7), and TRP vanilloid 3 (TRPV3) are carvacrol-regulated TRPs, however, effect of carvacrol on the peripheral neurodegenerative process, and its underlying mechanism, remain unclear. Here, we investigated the specificity of carvacrol for TRPM7 in Schwann cells and the regulatory effect of carvacrol on TRPM7-dependent neurodegenerative processes. To construct peripheral nerve degeneration model, we used with a sciatic explant culture and sciatic nerve axotomy. Ex vivo, in vivo sciatic nerves were treated with carvacrol following an assessment of demyelination (ovoid fragmentation) and axonal degradation using morphometric indices. In these models, carvacrol effectively suppressed the morphometric indices, such as stripe, ovoid, myelin, and neurofilament indices during peripheral nerve degeneration. We found that carvacrol significantly inhibited upregulation of TRPM7 in Schwann cells. In this study, our results suggest that carvacrol effectively protects against the peripheral neurodegenerative process via TRPM7-dependent regulation in Schwann cells. Thus, pharmacological use of carvacrol could be helpful to protect against neurodegeneration that occurs with aging and peripheral neurodegenerative diseases, prophylactically.

Latent turn-on fluorescent probe for the detection of toxic malononitrile in water and its practical applications.

A latent turn-on fluorescent probe for the detection of malononitrile (NCCH2CN), a precursor of hydrogen cyanide (HCN) in the mammalian tissue metabolism, is developed based on reaction-based fluorophore generation for the first time. Malononitrile is utilized within a wide spectrum of academic and industrial applications, and it is a key reagent to make o-chlorobenzylidene malononitrile (CS gas; tear gas), which is used for riot control. Due to its extensive use as well as potential health risks and the environmental pollution, malononitrile monitoring method has been required. In this paper, we discovered that our key sensing platform, 6-(dimethylamino)-3-hydroxy-2-naphthaldehyde (named Mal-P1), responds sensitively and selectively towards malononitrile. The Knoevenagel condensation induced benzo [g]coumarin formation of Mal-P1 with malononitrile showed significant fluorescence turn-on response. In addition, Mal-P1 showed the malononitrile sensing ability in environmental samples (real water, CS gas) and imaging ability in biological sample (HeLa cell line) using fluorescence microscopy with low cytotoxicity. The successful demonstrations will facilitate further applications in a variety of fields.

Heme Oxygenase 1 in Schwann Cells Regulates Peripheral Nerve Degeneration Against Oxidative Stress.

During Wallerian degeneration, Schwann cells lose their characteristic of myelinating axons and shift into the state of developmental promyelinating cells. This recharacterized Schwann cell guides newly regrowing axons to their destination and remyelinates reinnervated axons. This Schwann cell dynamics during Wallerian degeneration is associated with oxidative events. Heme oxygenases (HOs) are involved in the oxidative degradation of heme into biliverdin/bilirubin, ferrous iron, and carbon monoxide. Overproduction of ferrous iron by HOs increases reactive oxygen species, which have deleterious effects on living cells. Thus, the key molecule for understanding the exact mechanism of Wallerian degeneration in the peripheral nervous system is likely related to oxidative stress-mediated HOs in Schwann cells. In this study, we demonstrate that demyelinating Schwann cells during Wallerian degeneration highly express HO1, not HO2, and remyelinating Schwann cells during nerve regeneration decrease HO1 activation to levels similar to those in normal myelinating Schwann cells. In addition, HO1 activation during Wallerian degeneration regulates several critical phenotypes of recharacterized repair Schwann cells, such as demyelination, transdedifferentiation, and proliferation. Thus, these results suggest that oxidative stress in Schwann cells after peripheral nerve injury may be regulated by HO1 activation during Wallerian degeneration and oxidative-stress-related HO1 activation in Schwann cells may be helpful to study deeply molecular mechanism of Wallerian degeneration.

Fluorescence-Based Analysis of Noncanonical Functions of Aminoacyl-tRNA Synthetase-Interacting Multifunctional Proteins (AIMPs) in Peripheral Nerves.

Aminoacyl-tRNA synthetase-interacting multifunctional proteins (AIMPs) are auxiliary factors involved in protein synthesis related to aminoacyl-tRNA synthetases (ARSs). AIMPs, which are well known as nonenzymatic factors, include AIMP1/p43, AIMP2/p38, and AIMP3/p18. The canonical functions of AIMPs include not only protein synthesis via multisynthetase complexes but also maintenance of the structural stability of these complexes. Several recent studies have demonstrated nontypical (noncanonical) functions of AIMPs, such as roles in apoptosis, inflammatory processes, DNA repair, and so on. However, these noncanonical functions of AIMPs have not been studied in peripheral nerves related to motor and sensory functions. Peripheral nerves include two types of structures: peripheral axons and Schwann cells. The myelin sheath formed by Schwann cells produces saltatory conduction, and these rapid electrical signals control motor and sensory functioning in the service of survival in mammals. Schwann cells play roles not only in myelin sheath formation but also as modulators of nerve degeneration and regeneration. Therefore, it is important to identify the main functions of Schwann cells in peripheral nerves. Here, using immunofluorescence technique, we demonstrated that AIMPs are essential morphological indicators of peripheral nerve degeneration, and their actions are limited to peripheral nerves and not the dorsal root ganglion and the ventral horn of the spinal cord.

Frontiers in Probing Alzheimer's Disease Biomarkers with Fluorescent Small Molecules.

Alzheimer's disease (AD) is the most common form of dementia. The pathogenesis of the disease is associated with aggregated amyloid-ß, hyperphosphorylated tau, a high level of metal ions, abnormal enzyme activities, and reactive astrocytes. This outlook gives an overview of fluorescent small molecules targeting AD biomarkers for ex vivo and in vivo imaging. These chemical imaging probes are categorized based on the potential biomarkers, and their pros and cons are discussed. Guidelines for designing new sensing strategies as well as the desirable properties to be pursued for AD fluorescence imaging are also provided.

Mitophagy links oxidative stress conditions and neurodegenerative diseases.

Mitophagy is activated by a number of stimuli, including hypoxia, energy stress, and increased oxidative phosphorylation activity. Mitophagy is associated with oxidative stress conditions and central neurodegenerative diseases. Proper regulation of mitophagy is crucial for maintaining homeostasis; conversely, inadequate removal of mitochondria through mitophagy leads to the generation of oxidative species, including reactive oxygen species and reactive nitrogen species, resulting in various neurodegenerative diseases, such as Alzheimer's disease, Parkinson's disease, Huntington's disease, and amyotrophic lateral sclerosis. These diseases are most prevalent in older adults whose bodies fail to maintain proper mitophagic functions to combat oxidative species. As mitophagy is essential for normal body function, by targeting mitophagic pathways we can improve these disease conditions. The search for effective remedies to treat these disease conditions is an ongoing process, which is why more studies are needed. Additionally, more relevant studies could help establish therapeutic conditions, which are currently in high demand. In this review, we discuss how mitophagy plays a significant role in homeostasis and how its dysregulation causes neurodegeneration. We also discuss how combating oxidative species and targeting mitophagy can help treat these neurodegenerative diseases.

Benzo[g]coumarin-Based Fluorescent Probes for Bioimaging Applications.

Benzo[g]coumarins, which consist of coumarins fused with other aromatic units in the linear shape, have recently emerged as an interesting fluorophore in the bioimaging research. The pi-extended skeleton with the presence of electron-donating and electron-withdrawing substituents from the parent coumarins changes the basic photophysical parameters such as absorption and fluorescence emission significantly. Most of the benzo[g]coumarin analogues show red/far-red fluorescence emission with high two-photon absorbing property that can be applicable for the two-photon microscopy (TPM) imaging. In this review, we summarized the recently developed benzo[g]coumarin analogues including photophysical properties, synthesis, and applications for molecular probes that can sense biologically important species such as metal ions, cell organs, reactive species, and disease biomarkers.

Ginger fermented with Schizosaccharomyces pombe alleviates memory impairment via protecting hippocampal neuronal cells in amyloid beta1-42 plaque injected mice.

Ginger, which has been widely used for dietary condiment, has been reported to improve memory dysfunction in an animal model of Alzheimer's disease (AD). Recently, a few trials have been carried out to enhance the effects of ginger by improving the bioavailability of its relevant components via fermentation. Some reports have suggested that the fermented ginger has the ability to affect the AD in vitro systems; however, its anti-amnesic effects on an in vivo model still remain to be investigated. In the present study, we aimed to investigate the neuroprotective effects of ginger fermented with Schizosaccharomyces pombe (FG) in the in vivo models of AD. The neuroprotective effects were investigated by employing behavioral, western blotting, and immunohistochemical assays. The administration of FG improved recognition memory, impaired by scopolamine injection, than that of non-fermented ginger. In addition, FG ameliorated memory impairment in amyloid beta1-42 (Aß1-42) plaque-injected mice via protecting neuronal cells in the CA3 area of the mouse hippocampus. Moreover, FG reinstated the pre- and postsynaptic protein levels decreased by Aß1-42 plaque-toxicity. Overall, these data suggest that FG attenuates memory impairment in Aß1-42 plaque-induced AD mice through inhibition of neuronal cell loss and synaptic disruption.

Fluorescent Labeling of Protein Using Blue-Emitting 8-Amino-BODIPY Derivatives.

8-Amino-BODIPY (boron-dipyrromethane) dyes show bright blue fluorescence. Disclosed here are synthesis and characterization of the photophysical properties of a series of functionalized 8-Amino-BODIPY (BP1-4) for protein labeling. The compact structure and solvent-insensitive absorption property of the dye are desirable features for protein labeling. For the model protein, bovine serum albumin (BSA), the labeling proceeds under mild condition via amide bond formation or thiol-ene conjugation with maintaining the bright blue fluorescence. The chromatography and mass spectroscopy analysis clearly support the labeling of the BODIPY dye on the BSA. The protein labeling with blue-emitting BODIPY would be applicable for studying protein dynamics and fluorescence resonance energy transfer (FRET) with intrinsic biomolecules.

Two-Photon In Vivo Imaging with Porous Silicon Nanoparticles.

A major obstacle in luminescence imaging is the limited penetration of visible light into tissues and interference associated with light scattering and autofluorescence. Near-infrared (NIR) emitters that can also be excited with NIR radiation via two-photon processes can mitigate these factors somewhat because they operate at wavelengths of 650-1000 nm where tissues are more transparent, light scattering is less efficient, and endogenous fluorophores are less likely to absorb. This study presents photolytically stable, NIR photoluminescent, porous silicon nanoparticles with a relatively high two-photon-absorption cross-section and a large emission quantum yield. Their ability to be targeted to tumor tissues in vivo using the iRGD targeting peptide is demonstrated, and the distribution of the nanoparticles with high spatial resolution is visualized.

Anatomical distributional defects in mutant genes associated with dominant intermediate Charcot-Marie-Tooth disease type C in an adenovirus-mediated mouse model.

Dominant intermediate Charcot-Marie-Tooth disease type C (DI-CMTC) is a dominantly inherited neuropathy that has been classified primarily based on motor conduction velocity tests but is now known to involve axonal and demyelination features. DI-CMTC is linked to tyrosyl-tRNA synthetase (YARS)-associated neuropathies, which are caused by E196K and G41R missense mutations and a single de novo deletion (153-156delVKQV). It is well-established that these YARS mutations induce neuronal dysfunction, morphological symptoms involving axonal degeneration, and impaired motor performance. The present study is the first to describe a novel mouse model of YARS-mutation-induced neuropathy involving a neuron-specific promoter with a deleted mitochondrial targeting sequence that inhibits the expression of YARS protein in the mitochondria. An adenovirus vector system and in vivo techniques were utilized to express YARS fusion proteins with a Flag-tag in the spinal cord, peripheral axons, and dorsal root ganglia. Following transfection of YARS-expressing viruses, the distributions of wild-type (WT) YARS and E196K mutant proteins were compared in all expressed regions; G41R was not expressed. The proportion of Flag/green fluorescent protein (GFP) double-positive signaling in the E196K mutant-type mice did not significantly differ from that of WT mice in dorsal root ganglion neurons. All adenovirus genes, and even the empty vector without the YARS gene, exhibited GFP-positive signaling in the ventral horn of the spinal cord because GFP in an adenovirus vector is driven by a cytomegalovirus promoter. The present study demonstrated that anatomical differences in tissue can lead to dissimilar expressions of YARS genes. Thus, use of this novel animal model will provide data regarding distributional defects between mutant and WT genes in neurons, the DI-CMTC phenotype, and potential treatment approaches for this disease.

Role of Gasotransmitters in Oxidative Stresses, Neuroinflammation, and Neuronal Repair.

To date, three main gasotransmitters, that is, hydrogen sulfide (H2S), carbon monoxide (CO), and nitric oxide (NO), have been discovered to play major bodily physiological roles. These gasotransmitters have multiple functional roles in the body including physiologic and pathologic functions with respect to the cellular or tissue quantities of these gases. Gasotransmitters were originally known to have only detrimental and noxious effects in the body but that notion has much changed with years; vast studies demonstrated that these gasotransmitters are precisely involved in the normal physiological functioning of the body. From neuromodulation, oxidative stress subjugation, and cardiovascular tone regulation to immunomodulation, these gases perform critical roles, which, should they deviate from the norm, can trigger the genesis of a number of neurodegenerative diseases such as Alzheimer's disease (AD) and Parkinson's disease (PD). The purpose of this review is to discuss at great length physical and chemical properties and physiological actions of H2S, NO, and CO as well as shedding light on recently researched molecular targets. We particularly put emphasis on the roles in neuronal inflammation and neurodegeneration and neuronal repair.

A Dipolar Anthracene Dye: Synthesis, Optical Properties and Two-photon Tissue Imaging.

Two-photon microscopy is a powerful tool for studying biological systems. In search of novel two-photon absorbing dyes for bioimaging, we synthesized a new anthracene-based dipolar dye (anthradan) and evaluated its two-photon absorbing and imaging properties. The new anthradan, 9,10-bis(o-dimethoxy-phenyl)-anthradan, absorbs and emits at longer wavelengths than acedan, a well-known two-photon absorbing dye. It is also stable under two-photon excitation conditions and biocompatible, and thus used for two-photon imaging of mouse organ tissues to show bright, near-red fluorescence along with negligible autofluorescence. Such an anthradan thus holds promise as a new class of two-photon absorbing dyes for the development of fluorescent probes and tags for biological systems.

Differences in MR signal intensity of lateral collateral ligament of knee joint on fat-suppressed proton density-weighted imaging.

OBJECTIVE: To investigate the relationship between the increased signal intensity (SI) of proximal lateral collateral ligament (LCL) at femoral attachment site on fat-suppressed (FS) proton density-weighted (PDW) MR imaging and the corresponding histological features on cadaveric knees. METHODS: MRI was obtained from 11 cadaveric knees. Two musculoskeletal radiologists evaluated SI of LCL at femoral attachment site and the remaining caudal portion on FS PDW imaging. The SI was classified into three types; I = low, II = intermediate to slightly high, III = high SI or intraligamentous discontinuity of fibre. In addition, 100 control subjects were reviewed for normal LCL SI. RESULTS: All proximal LCLs at femoral attachment site showed increased SI (nine cases of Type II and two cases of Type III). The remaining caudal portion presented Type I in all cases. Histological examination of proximal LCL at femoral attachment site revealed loose distribution of fine collagen fibres, intervened with fat and vessels, whereas the remaining caudal portion was composed of parallel distribution of compact collagen bundles. There were no signs of degeneration or tear of the LCL in all our cadaveric knee samples, even for the two cases that presented as Type III. Clinical study identified increased SI of proximal LCL at femoral attachment site in 94% (94/100) of control subjects. CONCLUSION: Increased SI of proximal LCL at femoral attachment site on FS PDW imaging is due to histological characteristics, not degeneration or tear. ADVANCES IN KNOWLEDGE: Increased SI of proximal LCL at femoral attachment site on FS PDW MR imaging is a common, normal finding that its clinical significance can be neglected.