Loganin possesses neuroprotective properties, restores SMN protein and activates protein synthesis positive regulator Akt/mTOR in experimental models of spinal muscular atrophy

Loganin exerts neuroprotective effect by inhibiting neuronal pyroptosis in rat with cerebral haemorrhage

Intracerebral haemorrhage (ICH) presents significant challenges in clinical management because of the high morbidity and mortality, necessitating novel therapeutic approaches. This study aimed to assess the neuroprotective effects of loganin in a rat ICH model. Sprague-Dawley rats were used, subjected to a collagenase-induced ICH model, followed by loganin treatment at doses of 2.5, 5 and 10 mg/kg. Neurological functions were evaluated using the modified neurological severity score (mNSS) and a rotarod test. Results indicated a significant improvement in neurological functions in loganin-treated groups, evident from the mNSS and rotarod tests, suggesting dose-dependent neuroprotection. Loganin also effectively reduced the blood-brain barrier (BBB) permeability and cerebral oedema. Additionally, it mitigated cellular pyroptosis, as shown by terminal deoxynucleotidyl transferase dUTP nick-end labelling staining and western blot analysis, which indicated reduced levels of pyroptosis markers in treated rats. Furthermore, loganin's regulatory effects on the adenosine A2A receptor and myosin light chain kinase pathways were observed, potentially underpinning its protective mechanism against ICH. The study concludes that loganin exhibits significant neuroprotective properties in a rat ICH model, highlighting its potential as a novel therapeutic strategy. Despite promising results, the study needs further research to determine loganin's therapeutic potential in human ICH patients. This research paves the way for further exploration into loganin's clinical applications, potentially revolutionizing treatment strategies for patients suffering from intracerebral haemorrhage.

Running improves muscle mass by activating autophagic flux and inhibiting ubiquitination degradation in mdx mice

BACKGROUND

Exercise therapy can improve muscle mass, strengthen muscle and cardiorespiratory function, and may be an excellent adjunctive treatment option for Duchenne muscular dystrophy.

METHODS

This article investigates the effects of 10 weeks of treadmill training on skeletal muscle in control and mdx mice. Hematoxylin and eosin (H&E) staining was used to detect the morphometry of skeletal muscle; the grip strength test, suspension test, and rotarod test were used to detect limb muscle strength of mice, and Aurora Scientific Instruments were used to detect in vivo Muscle Stimulation Measuring Maximum Force of pre-fatigue and post-fatigue. The expression levels of myogenic proteins, ubiquitination markers, autophagy pathway proteins, and the proportion of different muscle fiber types were detected.

RESULTS

The experimental results show that running exercise can significantly improve the muscle mass of mdx mice, promote muscle strength, endurance, and anti-fatigue ability, reverse the pathological state of skeletal muscle destruction in mdx mice, and promote muscle regeneration. WB experiments showed that running inhibited the ubiquitination and degradation of muscle protein in mdx mice, inhibited AKT activation, decreased phosphorylated FoxO1 and FoxO3a, and restored the suppressed autophagic flux. Running enhances muscle strength and endurance by comprehensively promoting the expression of Myh1/2/4/7 fast and slow muscle fibers in mdx mice.

CONCLUSIONS

Running can inhibit the degradation of muscle protein in mdx mice, and promote the reuse and accumulation of proteins, thereby slowing down muscle loss. Running improves skeletal muscle mass by activating autophagic flux and inhibiting ubiquitination degradation in mdx mice.

The SMN-ribosome interplay: a new opportunity for Spinal Muscular Atrophy therapies

The underlying cause of Spinal Muscular Atrophy (SMA) is in the reduction of survival motor neuron (SMN) protein levels due to mutations in the SMN1 gene. The specific effects of SMN protein loss and the resulting pathological alterations are not fully understood. Given the crucial roles of the SMN protein in snRNP biogenesis and its interactions with ribosomes and translation-related proteins and mRNAs, a decrease in SMN levels below a specific threshold in SMA is expected to affect translational control of gene expression. This review covers both direct and indirect SMN interactions across various translation-related cellular compartments and processes, spanning from ribosome biogenesis to local translation and beyond. Additionally, it aims to outline deficiencies and alterations in translation observed in SMA models and patients, while also discussing the implications of the relationship between SMN protein and the translation machinery within the context of current and future therapies.

Brain-derived neurotrophic factor/tropomyosin receptor kinase B signaling in spinal muscular atrophy and amyotrophic lateral sclerosis

Tropomyosin receptor kinase B (TrkB) and its primary ligand brain-derived neurotrophic factor (BDNF) are expressed in the neuromuscular system, where they affect neuronal survival, differentiation, and functions. Changes in BDNF levels and full-length TrkB (TrkB-FL) signaling have been revealed in spinal muscular atrophy (SMA) and amyotrophic lateral sclerosis (ALS), two common forms of motor neuron diseases that are characterized by defective neuromuscular junctions in early disease stages and subsequently progressive muscle weakness. This review summarizes the current understanding of BDNF/TrkB-FL-related research in SMA and ALS, with an emphasis on their alterations in the neuromuscular system and possible BDNF/TrkB-FL-targeting therapeutic strategies. The limitations of current studies and future directions are also discussed, giving the hope of discovering novel and effective treatments.

Spinal Muscular Atrophy Treatment: The MTOR Regulatory Intervention

Spinal muscular atrophy (SMA) is a hereditary disorder affecting neurons and muscles, resulting in muscle weakness and atrophy. Most SMA cases are diagnosed during infancy or early childhood, the most common inherited cause of infant mortality without treatment. Still, SMA might appear at older ages with milder symptoms. SMA patients demonstrate progressive muscle waste, movement problems, tremors, dysphagia, bone and joint deformations, and breathing difficulties. The mammalian target of rapamycin (mTOR), the mechanistic target of rapamycin, is a member of the phosphatidylinositol 3-kinase-related kinase family of protein kinases encoded by the mTOR gene in humans. The mTOR phosphorylation, deregulation, and autophagy have shown dissimilarity amongst SMA cell types. Therefore, exploring the underlying molecular process in SMA therapy could provide novel insights and pave the way for finding new treatment options. This paper provides new insight into the possible modulatory effect of mTOR/ autophagy in SMA management.

Iridoids and active ones in patrinia: A review

Iridoid is a special class of monoterpenoids, whose basic skeleton is the acetal derivative of antinodilaldehyde with a bicyclic H-5/H-9β, β-cisfused cyclopentan pyran ring. They were often existed in Valerianaceae, Rubiaceae, Scrophulariaceae and Labiaceae family, and has various biological activities, such as anti-inflammatory, hypoglycemic, neuroprotection, and soon. In this review, iridoids from Patrinia (Valerianaceae family), and the active ones as well as their mechanisms in recent 20 years were summarized. Up to now, a total of 115 iridoids had been identified in Patrinia, among which 48 had extensive biological activities mainly presented in anti-inflammatory, anti-tumor and neuroprotective. And the mechanisms involved in MAPK, NF-κB and JNK signal pathways. The summary for iridoids and their activities will provide the evidence to exploit the iridoids in Patrinia.

Loganin improves chronic unpredictable mild stress-induced depressive-like behaviors and neurochemical dysfunction

ETHNOPHARMACOLOGICAL RELEVANCE

Cornus officinalis Sieb. et Zucc., is a valuable herb commonly used in Chinese medicine clinics. Loganin is a major iridoid glycoside obtained from the traditional Chinese herb Corni Fructus. Loganin, which has been shown to improve depression-like behavior in mice exposed to acute stress, is probably a potential antidepressant candidate.

AIM OF THE STUDY

Loganin was evaluated for its effect on chronic unpredictable mild stress (CUMS) induced depressive-like mice, and its action mechanisms were explored.

MATERIALS AND METHODS

ICR mice were subjected to the CUMS stimulation method to induce depression. The therapeutic effect of loganin on depressive-like behavior was evaluated by a series of behavioral tests such as sucrose preference test (SPT), forced swim test (FST), tail suspension test (TST) and open-field test (OFT). In addition, the serum levels of adrenocorticotropic hormone (ACTH) and corticosterone (CORT) were measured using ELISA. The levels of monoamine neurotransmitters were detected by high performance liquid chromatography-electrochemical detection (HPLC-ECD). The levels of brain-derived neurotrophic factor (BDNF) in the hippocampus were measured using western blot analysis.

RESULTS

The results showed that CUMS induced depressive-like behaviors in mice, as indicated by behavioral tests. Administration of loganin increased the sucrose preference in SPT, as well as decreased the immobility time in FST and TST. Loganin could also improve food intake, and increased crossing times in the OFT. In mechanism, loganin restored the secretion of monoamine neurotransmitters, ACTH and CORT to normal levels. In addition, loganin elevated the expression of BDNF in the hippocampus. In conclusion, loganin exerts antidepressant-like effects in CUMS model mice through modulating monoamine neurotransmitters, ACTH, CORT and BDNF.

CONCLUSION

Loganin effectively ameliorated depressive-like symptoms in CUMS-exposed mice by increasing 5-hydroxytryptamine (5-HT) and dopamine (DA) levels, alleviating hypothalamic-pituitary-adrenal (HPA) axis dysfunction, and increasing BDNF expression. In conclusion, the findings of the current study extensive evidence for the application of loganin in stress-associated disorders, specifically targeting depression.

Loganin attenuates neuroinflammation after ischemic stroke and fracture by regulating α7nAChR-mediated microglial polarization

Fracture in acute stage of ischemic stroke can increase inflammatory response and enhance stroke injury. Loganin alleviates the symptoms of many inflammatory diseases through its anti-inflammatory effect, but its role in ischemic stroke and fracture remains to be explored. Here, mice were handled with permanent middle cerebral artery occlusion (pMCAO) followed by tibial fracture 1 day later to establish a pMCAO+fracture model. Loganin or Methyllycaconitine (MLA, a specific a7nAchR inhibitor) were intragastrically administered 2 or 0.5 h before pMCAO, respectively. And mouse motor function and infarct volume were evaluated 3 days after pMCAO. We found that loganin alleviated the neurological deficit, cerebral infarction volume, and neuronal apoptosis (NeuN⁺ TUNEL⁺ ) in mice with pMCAO+fracture. And loganin suppressed pMCAO+fracture-induced neuroinflammation by promoting M2 microglia polarization (Iba1⁺ CD206⁺ ) and inhibiting M1 microglia polarization (Iba1⁺ CD11b⁺ ). While administration with MLA reversed the protective effect of loganin on pMCAO+fracture-induced neurological deficit and neuroinflammation. Next, LPS was used to stimulate BV2 microglia to simulate pMCAO+fracture-induced inflammatory microenvironment in vitro. Loganin facilitated the transformation of LPS-stimulated BV2 cells from M1 pro-inflammatory state (CD11b⁺ ) to M2 anti-inflammatory state (CD206⁺ ), which was antagonized by treatment with MLA. And loganin induced autophagy activation in LPS-stimulated BV2 cells by activating a7nAchR. Moreover, treatment with rapamycin (an autophagy activator) neutralized the inhibitory effect of MLA on loganin induced transformation of BV2 cells to M2 phenotype. Furthermore, BV2 cells were treated with LPS, LPS + loganin, LPS + loganin+MLA, or LPS + loganin+MLA+ rapamycin to obtain conditioned medium (CM) for stimulating primary neurons. Loganin reduced the damage of primary neurons caused by LPS-stimulated BV2 microglia through activating a7nAchR and inducing autophagy activation. In conclusion, loganin played anti-inflammatory and neuroprotective roles in pMCAO + fracture mice by activating a7nAchR, enhancing autophagy and promoting M2 polarization of microglia.

Activation of Nrf2/HO-1 antioxidant signaling correlates with the preventive effect of loganin on oxidative injury in ARPE-19 human retinal pigment epithelial cells

BACKGROUND

Loganin, a type of iridoid glycoside derived from Corni Fructus, is known to have beneficial effects various chronic diseases. However, studies on mechanisms related to antioxidant efficacy in human retinal pigment epithelial (RPE) cells have not yet been conducted.

OBJECTIVES

This study was to investigate whether loganin could inhibit oxidative stress-mediated cellular damage caused by hydrogen peroxide (H₂O₂) in human RPE ARPE-19 cells.

METHODS

The preventive effect of loganin on H₂O₂-induced cytotoxicity, reactive oxygen species (ROS) generation, DNA damage and apoptosis was investigated. In addition, immunofluorescence staining and immunoblotting analysis were applied to evaluate the related mechanisms.

RESULTS

The loss of cell viability and increased ROS accumulation in H₂O₂-treated ARPE-19 cells were significantly abrogated by loganin pretreatment, which was associated with activation of nuclear factor erythroid 2-related factor 2 (Nrf2) and increased expression of heme oxygenase-1 (HO-1). Loganin also markedly attenuated H₂O₂-induced DNA damage, ultimately ameliorating apoptosis. In addition, H₂O₂-induced mitochondrial dysfunction was reversed in the presence of loganin as indicated by preservation of mitochondrial integrity, decrease of Bax/Bcl-2 expression ratio, reduction of caspase-3 activity and suppression of cytochrome c release into the cytoplasm. However, zinc protoporphyrin, a selective inhibitor of HO-1, remarkably alleviated the preventive effect offered by loganin against H₂O₂-mediated ARPE-19 cell injury, suggesting a critical role of Nrf2-mediated activation of HO-1 in the antioxidant activity of loganin.

CONCLUSION

The results of this study suggest that loganin-induced activation of the Nrf2/HO-1 axis is at least involved in protecting at least ARPE-19 cells from oxidative injury.

Loganin attenuates interleukin-1-induced chondrocyte inflammation, cartilage degeneration, and rat synovial inflammation by regulating TLR4/MyD88/NF-κB

Objective

Inflammation plays a crucial part in osteoarthritis (OA) development. This work aimed to explore loganin’s role and molecular mechanism in inflammation and clarify its anti-inflammatory effects in OA treatment.

Methods

Chondrocytes were stimulated using interleukin (IL)-1β and loganin at two concentrations (1 μM and 10 μM). Nitric oxide (NO) and prostaglandin E2 (PGE2) expression was assessed. Real-time polymerase chain reaction was used to evaluate inducible NO synthase (iNOS), cyclooxygenase (COX)-2, IL-6, and tumor necrosis factor (TNF)-α mRNA levels. Western blot was used to investigate TLR4, MyD88, p-p65, and IκB-α expression. p65 nuclear translocation, synovial inflammatory response, and cartilage degeneration were also assessed.

Results

Loganin significantly reduced IL-1β-mediated PGE2, NO, iNOS, and COX-2 expression compared with that of the IL-1β stimulation group. The TLR4/MyD88/NF-κB pathway was suppressed by loganin, which decreased inflammatory cytokine (TNF-α and IL-6) levels compared with those of the IL-1β stimulation group. Loganin inhibited IL-1β-mediated NF-κB p65 nuclear translocation compared with that of the IL-1β stimulation group. Loganin partially suppressed cartilage degeneration and the synovial inflammatory response in vivo.

Conclusion

This work demonstrated that loganin inhibited IL-1β-mediated inflammation in rat chondrocytes through TLR4/MyD88/NF-κB pathway regulation, thereby reducing rat cartilage degeneration and the synovial inflammatory response.

Phytochemistry, synthesis, analytical methods, pharmacological activity, and pharmacokinetics of loganin: A comprehensive review

Iridoid glycosides (IGs) are found in many medicinal and edible plants, such as Gardenia jasminoides, Cistanche tubulosa, Eucommia ulmoides, Rehmanniae Radix, Lonicera japonica, and Cornus officinalis. Loganin, an IG, is one of the main active ingredient of Cornus officinalis Sieb. et Zucc., which approved as a medicinal and edible plant in China. Loganin has been widely concerned due to its extensive pharmacological effects, including anti-diabetic, antiinflammatory, neuroprotective, and anti-tumor activities, etc. Studies have shown that these underlying mechanisms include anti-oxidation, antiinflammation and anti-apoptosis by regulating a variety of signaling pathways, such as STAT3/NF-κB, JAK/STAT3, TLR4/NF-κB, PI3K/Akt, MCP-1/CCR2, and RAGE/Nox4/p65 NF-κB signaling pathways. In order to better understand the research status of loganin and promote its application in human health, this paper systematically summarized the phytochemistry, analysis methods, synthesis, pharmacological properties and related mechanisms, and pharmacokinetics based on the research in the past decades.

Therapy development for spinal muscular atrophy: perspectives for muscular dystrophies and neurodegenerative disorders

BACKGROUND

Major efforts have been made in the last decade to develop and improve therapies for proximal spinal muscular atrophy (SMA). The introduction of Nusinersen/Spinraza™ as an antisense oligonucleotide therapy, Onasemnogene abeparvovec/Zolgensma™ as an AAV9-based gene therapy and Risdiplam/Evrysdi™ as a small molecule modifier of pre-mRNA splicing have set new standards for interference with neurodegeneration.

MAIN BODY

Therapies for SMA are designed to interfere with the cellular basis of the disease by modifying pre-mRNA splicing and enhancing expression of the Survival Motor Neuron (SMN) protein, which is only expressed at low levels in this disorder. The corresponding strategies also can be applied to other disease mechanisms caused by loss of function or toxic gain of function mutations. The development of therapies for SMA was based on the use of cell culture systems and mouse models, as well as innovative clinical trials that included readouts that had originally been introduced and optimized in preclinical studies. This is summarized in the first part of this review. The second part discusses current developments and perspectives for amyotrophic lateral sclerosis, muscular dystrophies, Parkinson's and Alzheimer's disease, as well as the obstacles that need to be overcome to introduce RNA-based therapies and gene therapies for these disorders.

CONCLUSION

RNA-based therapies offer chances for therapy development of complex neurodegenerative disorders such as amyotrophic lateral sclerosis, muscular dystrophies, Parkinson's and Alzheimer's disease. The experiences made with these new drugs for SMA, and also the experiences in AAV gene therapies could help to broaden the spectrum of current approaches to interfere with pathophysiological mechanisms in neurodegeneration.

Exosomal hsa_circ_0125310 promotes cell proliferation and fibrosis in diabetic nephropathy via sponging miR-422a and targeting the IGF1R/p38 axis

Diabetic nephropathy (DN) is still on the rise worldwide, and millions of patients have to be treated through dialysis or transplant because of kidney failure caused by DN. Recent reports have highlighted circRNAs in the treatment of DN. Herein, we aimed to investigate the mechanism by which high glucose‐induced exo‐circ_0125310 promotes diabetic nephropathy progression. circ_0125310 is highly expressed in diabetic nephropathy and exosomes isolated from high glucose‐induced mesangial cells (MCs). High glucose‐induced exosomes promote the proliferation and fibrosis of MCs. However, results showed that the effects of exosomes on MCs can be reversed by the knockdown of circ_0125310. miR‐422a, which targets IGF1R, was the direct target of circ_0125310. circ_0125310 regulated IGF1R/p38 axis by sponging miR‐422a. Exo‐circ_0125310 increased the luciferase activity of the WT‐IGF1R reporter in the dual‐luciferase reporter gene assays and upregulated the expression level of IGF1R and p38. Finally, in vivo research indicated that the overexpression of circ_0125310 promoted the diabetic nephropathy progression. Above results demonstrated that the high glucose‐induced exo‐circ_0125310 promoted cell proliferation and fibrosis in diabetic nephropathy via sponging miR‐422a and targeting the IGF1R/p38 axis.

Autophagy and apoptosis cascade: which is more prominent in neuronal death?

Autophagy and apoptosis are two crucial self-destructive processes that maintain cellular homeostasis, which are characterized by their morphology and regulated through signal transduction mechanisms. These pathways determine the fate of cellular organelle and protein involved in human health and disease such as neurodegeneration, cancer, and cardiovascular disease. Cell death pathways share common molecular mechanisms, such as mitochondrial dysfunction, oxidative stress, calcium ion concentration, reactive oxygen species, and endoplasmic reticulum stress. Some key signaling molecules such as p53 and VEGF mediated angiogenic pathway exhibit cellular and molecular responses resulting in the triggering of apoptotic and autophagic pathways. Herein, based on previous studies, we describe the intricate relation between cell death pathways through their common genes and the role of various stress-causing agents. Further, extensive research on autophagy and apoptotic machinery excavates the implementation of selective biomarkers, for instance, mTOR, Bcl-2, BH3 family members, caspases, AMPK, PI3K/Akt/GSK3β, and p38/JNK/MAPK, in the pathogenesis and progression of neurodegenerative diseases. This molecular phenomenon will lead to the discovery of possible therapeutic biomolecules as a pharmacological intervention that are involved in the modulation of apoptosis and autophagy pathways. Moreover, we describe the potential role of micro-RNAs, long non-coding RNAs, and biomolecules as therapeutic agents that regulate cell death machinery to treat neurodegenerative diseases. Mounting evidence demonstrated that under stress conditions, such as calcium efflux, endoplasmic reticulum stress, the ubiquitin-proteasome system, and oxidative stress intermediate molecules, namely p53 and VEGF, activate and cause cell death. Further, activation of p53 and VEGF cause alteration in gene expression and dysregulated signaling pathways through the involvement of signaling molecules, namely mTOR, Bcl-2, BH3, AMPK, MAPK, JNK, and PI3K/Akt, and caspases. Alteration in gene expression and signaling cascades cause neurotoxicity and misfolded protein aggregates, which are characteristics features of neurodegenerative diseases. Excessive neurotoxicity and misfolded protein aggregates lead to neuronal cell death by activating death pathways like autophagy and apoptosis. However, autophagy has a dual role in the apoptosis pathways, i.e., activation and inhibition of the apoptosis signaling. Further, micro-RNAs and LncRNAs act as pharmacological regulators of autophagy and apoptosis cascade, whereas, natural compounds and chemical compounds act as pharmacological inhibitors that rescue neuronal cell death through inhibition of apoptosis and autophagic cell death.

Loganin prevents CXCL12/CXCR4-regulated neuropathic pain via the NLRP3 inflammasome axis in nerve-injured rats

BACKGROUND

Neuropathic pain has been shown to be modulated by the activation of the chemokine C-X-C motif ligand 12 (CXCL12)/chemokine CXC receptor 4 (CXCR4) dependent nucleotide-binding oligomerization domain (NOD)-like receptor protein 3 (NLRP3) inflammasome. Loganin, an iridoid glycoside, was proven to prevent neuropathic pain, but its underlying mechanisms related to NLRP3 activation are still unknown.

PURPOSE

This study investigated the underlying mechanisms of loganin's effect on chronic constriction injury (CCI)-induced NLRP3 inflammasome activation in the spinal cord.

METHODS

Sprague-Dawley rats were randomly divided into four groups: sham, CCI, sham + loganin, and CCI + loganin. Loganin (5 mg/kg/day) was administered intraperitoneally starting the day after surgery. Paw withdrawal threshold (PWT) and latency (PWL) were assessed before CCI and on days 1, 3, 7 and 14 after CCI. Spinal cords were collected for western blots and immunofluorescence studies.

RESULTS

Loganin prevented CCI-attenuated PWT and PWL, suggesting improved mechanical allodynia and thermal hyperalgesia. The expression of CXCL12, CXCR4, thioredoxin-interacting protein (TXNIP), NLRP3 inflammasome (NLRP3, ASC, and caspase-1), IL-1β, and IL-18 were enhanced on day 7 after CCI, and all were reduced after loganin treatment. Dual immunofluorescence also showed that increased CXCL12, CXCR4, and NLRP3 were colocalized with NeuN (neuronal marker), GFAP (astrocyte marker), and Iba1 (microglial marker) on day 7 in the ipsilateral spinal dorsal horn (SDH). These immunoreactivities were attenuated in loganin-treated rats. Moreover, loganin decreased the assembly of NLRP3/ASC inflammasome after CCI in the ipsilateral SDH. Loganin appears to attenuate CCI-induced neuropathic pain by suppressing CXCL12/CXCR4-mediated NLRP3 inflammasome.

CONCLUSION

Our findings suggest that loganin might be a suitable candidate for managing CCI-provoked neuropathic pain.

Spinal Muscular Atrophy autophagy profile is tissue-dependent: differential regulation between muscle and motoneurons

Spinal muscular atrophy (SMA) is a neuromuscular genetic disease caused by reduced survival motor neuron (SMN) protein. SMN is ubiquitous and deficient levels cause spinal cord motoneurons (MNs) degeneration and muscle atrophy. Nevertheless, the mechanism by which SMN reduction in muscle contributes to SMA disease is not fully understood. Therefore, studies evaluating atrophy mechanisms in SMA muscles will contribute to strengthening current knowledge of the pathology. Here we propose to evaluate autophagy in SMA muscle, a pathway altered in myotube atrophy. We analized autophagy proteins and mTOR in muscle biopsies, fibroblasts, and lymphoblast cell lines from SMA patients and in gastrocnemius muscles from a severe SMA mouse model. Human MNs differentiated from SMA and unaffected control iPSCs were also included in the analysis of the autophagy. Muscle biopsies, fibroblasts, and lymphoblast cell lines from SMA patients showed reduction of the autophagy marker LC3-II. In SMA mouse gastrocnemius, we observed lower levels of LC3-II, Beclin 1, and p62/SQSTM1 proteins at pre-symptomatic stage. mTOR phosphorylation at Ser2448 was decreased in SMA muscle cells. However, in mouse and human cultured SMA MNs mTOR phosphorylation and LC3-II levels were increased. These results suggest a differential regulation in SMA of the autophagy process in muscle cells and MNs. Opposite changes in autophagy proteins and mTOR phosphorylation between muscle cells and neurons were observed. These differences may reflect a specific response to SMN reduction, which could imply diverse tissue-dependent reactions to therapies that should be taken into account when treating SMA patients.

Loganin Inhibits Angiotensin II-Induced Cardiac Hypertrophy Through the JAK2/STAT3 and NF-κB Signaling Pathways

Loganin is an iridoid glycoside extracted from Cornus officinalis, which is a traditional oriental medicine, and many biological properties of loganin have been reported. Nevertheless, it is not clear whether loganin has therapeutic effect on cardiovascular diseases. Hence, the aim of the present study was to investigate the effect of loganin on Ang II-induced cardiac hypertrophy. In the present study, we reported for the first time that loganin inhibits Ang II-provoked cardiac hypertrophy and cardiac damages in H9C2 cells and in mice. Furthermore, loganin can achieve cardioprotective effects through attenuating cardiac fibrosis, decreasing pro-inflammatory cytokine secretion, and suppressing the phosphorylation of critical proteins such as JAK2, STAT3, p65, and IκBα. Besides, the outstanding findings of the present study were to prove that loganin has no significant toxicity or side effects on normal cells and organs. Based on these results, we conclude that loganin mitigates Ang II-induced cardiac hypertrophy at least partially through inhibiting the JAK2/STAT3 and NF-κB signaling pathways. Accordingly, the natural product, loganin, might be a novel effective agent for the treatment of cardiac hypertrophy and heart failure.

TOR signaling regulates liquid phase separation of the SMN complex governing snRNP biogenesis

The activity of the SMN complex in promoting the assembly of pre-mRNA processing UsnRNPs correlates with condensation of the complex in nuclear Cajal bodies. While mechanistic details of its activity have been elucidated, the molecular basis for condensation remains unclear. High SMN complex phosphorylation suggests extensive regulation. Here, we report on systematic siRNA-based screening for modulators of the capacity of SMN to condense in Cajal bodies and identify mTOR and ribosomal protein S6 kinase β-1 as key regulators. Proteomic analysis reveals TOR-dependent phosphorylations in SMN complex subunits. Using stably expressed or optogenetically controlled phospho mutants, we demonstrate that serine 49 and 63 phosphorylation of human SMN controls the capacity of the complex to condense in Cajal bodies via liquid-liquid phase separation. Our findings link SMN complex condensation and UsnRNP biogenesis to cellular energy levels and suggest modulation of TOR signaling as a rational concept for therapy of the SMN-linked neuromuscular disorder spinal muscular atrophy.

Loganin Inhibits Lipopolysaccharide-Induced Inflammation and Oxidative Response through the Activation of the Nrf2/HO-1 Signaling Pathway in RAW264.7 Macrophages

Inflammation caused by the excessive secretion of inflammatory mediators in abnormally activated macrophages promotes many diseases along with oxidative stress. Loganin, a major iridoid glycoside isolated from Cornus officinalis, has recently been reported to exhibit anti-inflammatory and antioxidant effects, whereas the underlying mechanism has not yet been fully clarified. Therefore, the aim of the present study is to investigate the effect of loganin on inflammation and oxidative stress in lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages. Our results indicated that loganin treatment markedly attenuated the LPS-mediated phagocytic activity and release of nitric oxide (NO) and prostaglandin E₂, which was associated with decreased the expression of inducible NO synthase and cyclooxygenase-2. In addition, loganin suppressed the expression and their extracellular secretion of LPS-induced pro-inflammatory cytokines, such as tumor necrosis factor-α and interleukin-1β. Furthermore, loganin abolished reactive oxygen species (ROS) generation, and promoted the activation of nuclear factor-E2-related factor 2 (Nrf2) and the expression of heme oxygenase-1 (HO-1) in LPS-stimulated macrophages. However, zinc protoporphyrin, a selective HO-1 inhibitor, reversed the loganin-mediated suppression of pro-inflammatory cytokines in LPS-treated macrophages. In conclusion, our findings suggest that the upregulation of the Nrf2/HO-1 signaling pathway is concerned at least in the protective effect of loganin against LPS-mediated inflammatory and oxidative stress, and that loganin can be a potential functional agent to prevent inflammatory and oxidative damage.

Metabolic Dysfunction in Spinal Muscular Atrophy

Spinal muscular atrophy (SMA) is an autosomal recessive genetic disorder leading to paralysis, muscle atrophy, and death. Significant advances in antisense oligonucleotide treatment and gene therapy have made it possible for SMA patients to benefit from improvements in many aspects of the once devastating natural history of the disease. How the depletion of survival motor neuron (SMN) protein, the product of the gene implicated in the disease, leads to the consequent pathogenic changes remains unresolved. Over the past few years, evidence toward a potential contribution of gastrointestinal, metabolic, and endocrine defects to disease phenotype has surfaced. These findings ranged from disrupted body composition, gastrointestinal tract, fatty acid, glucose, amino acid, and hormonal regulation. Together, these changes could have a meaningful clinical impact on disease traits. However, it is currently unclear whether these findings are secondary to widespread denervation or unique to the SMA phenotype. This review provides an in-depth account of metabolism-related research available to date, with a discussion of unique features compared to other motor neuron and related disorders.

Intracellular pathways involved in cell survival are deregulated in mouse and human spinal muscular atrophy motoneurons

Spinal Muscular Atrophy (SMA) is a severe neuromuscular disorder caused by loss of the Survival Motor Neuron 1 gene (SMN1). Due to this depletion of the survival motor neuron (SMN) protein, the disease is characterized by the degeneration of spinal cord motoneurons (MNs), progressive muscular atrophy, and weakness. Nevertheless, the ultimate cellular and molecular mechanisms leading to cell loss in SMN-reduced MNs are only partially known. We have investigated the activation of apoptotic and neuronal survival pathways in several models of SMA cells. Even though the antiapoptotic proteins FAIM-L and XIAP were increased in SMA MNs, the apoptosis executioner cleaved-caspase-3 was also elevated in these cells, suggesting the activation of the apoptosis process. Analysis of the survival pathway PI3K/Akt showed that Akt phosphorylation was reduced in SMA MNs and pharmacological inhibition of PI3K diminished SMN and Gemin2 at transcriptional level in control MNs. In contrast, ERK phosphorylation was increased in cultured mouse and human SMA MNs. Our observations suggest that apoptosis is activated in SMA MNs and that Akt phosphorylation reduction may control cell degeneration, thereby regulating the transcription of Smn and other genes related to SMN function.

In Search of a Cure: The Development of Therapeutics to Alter the Progression of Spinal Muscular Atrophy

Until the recent development of disease-modifying therapeutics, spinal muscular atrophy (SMA) was considered a devastating neuromuscular disease with a poor prognosis for most affected individuals. Symptoms generally present during early childhood and manifest as muscle weakness and progressive paralysis, severely compromising the affected individual’s quality of life, independence, and lifespan. SMA is most commonly caused by the inheritance of homozygously deleted SMN1 alleles with retention of one or more copies of a paralog gene, SMN2, which inversely correlates with disease severity. The recent advent and use of genetically targeted therapies have transformed SMA into a prototype for monogenic disease treatment in the era of genetic medicine. Many SMA-affected individuals receiving these therapies achieve traditionally unobtainable motor milestones and survival rates as medicines drastically alter the natural progression of this disease. This review discusses historical SMA progression and underlying disease mechanisms, highlights advances made in therapeutic research, clinical trials, and FDA-approved medicines, and discusses possible second-generation and complementary medicines as well as optimal temporal intervention windows in order to optimize motor function and improve quality of life for all SMA-affected individuals.

The Antioxidant, Anti-Inflammatory, and Neuroprotective Properties of the Synthetic Chalcone Derivative AN07

Chalcones belong to a class of biologically active polyphenolic natural products. As a result of their simple chemical nature, they are easily synthesized and show a variety of promising biological activities. 2-Hydroxy-4′-methoxychalcone (AN07) is a synthetic chalcone derivate with potential anti-atherosclerosis effects. In this study, we demonstrated the novel antioxidant, anti-inflammatory, and neuroprotective effects of AN07. In RAW 264.7 macrophages, AN07 attenuated lipopolysaccharide (LPS)-induced elevations in reactive oxygen species (ROS) level and oxidative stress via down-regulating gp91^phox expression and stimulating the antioxidant system of nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1) pathways, which were accompanied by increased glutathione (GSH) levels. Additionally, AN07 attenuated LPS-induced inflammatory factors, including NO, inducible NO synthase (iNOS), cyclooxygenase-2 (COX-2), and phosphorylated inhibitor of nuclear factor kappa B-alpha (p-IκBα) in RAW 264.7 macrophages. However, the effects of AN07 on promoting nuclear Nrf2 levels and decreasing COX-2 expressions were significantly abrogated by the peroxisome proliferator-activated receptor-γ (PPARγ) antagonist GW9662. In human dopaminergic SH-SY5Y cells treated with or without methylglyoxal (MG), a toxic endogenous by-product of glycolysis, AN07 up-regulated neurotrophic signals including insulin-like growth factor 1 receptor (IGF-1R), p-Akt, p-GSK3β, glucagon-like peptide 1 receptor (GLP-1R), and brain-derived neurotrophic factor (BDNF). AN07 attenuated MG-induced apoptosis by up-regulating the B-cell lymphoma 2 (Bcl-2) protein and down-regulating the cytosolic expression of cytochrome c. AN07 also attenuated MG-induced neurite damage via down-regulating the Rho-associated protein kinase 2 (ROCK2)/phosphorylated LIM kinase 1 (p-LIMK1) pathway. Moreover, AN07 ameliorated the MG-induced down-regulation of neuroprotective Parkinsonism-associated proteins parkin, pink1, and DJ-1. These findings suggest that AN07 possesses the potentials to be an anti-inflammatory, antioxidant, and neuroprotective agent

Loganin attenuates intestinal injury in severely burned rats by regulating the toll-like receptor 4/NF-κB signaling pathway

Severe burns may lead to intestinal inflammation and oxidative stress, resulting in intestinal barrier damage and gut dysfunction. Loganin, an iridoid glycoside compound, has been isolated from Cornus officinalis Sieb. et Zucc; however, its role in the treatment of burn injury is yet to be fully elucidated. Therefore, the present study examined the effect of loganin administration on burn-induced intestinal inflammation and oxidative stress after severe burns in male Sprague-Dawley rats. Histological injury was assessed by hematoxylin and eosin staining. Furthermore, cytokine expression in intestinal tissues was measured by ELISA and reverse transcription-quantitative PCR. Antioxidative activities were assessed by determining the levels of reactive oxygen species (ROS), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px) and malondialdehyde (MDA). Apoptosis was detected by flow cytometry. Apoptosis-related proteins, toll-like receptor 4 (TLR4) protein and NF-κB translocation were examined by western blotting. Immunohistochemical staining was used to observe TLR4 and NF-κB p65 expression in intestinal tissues. The present study suggested that loganin administration significantly reduced burn injury-induced intestinal histological changes, tumor necrosis factor-α, interleukin (IL)-6 and IL-1β production and oxidative stress, evidenced by decreased ROS levels and MDA content (P<0.05). Furthermore, loganin increased SOD, CAT and GSH-Px levels and intestinal epithelial cell apoptosis. Loganin treatment also significantly inhibited activation of the TLR4/NF-κB signaling pathway in the intestine of severely burned rats (P<0.05). In conclusion, loganin reduced burns-induced intestinal inflammation and oxidative stress, potentially by regulating the TLR4/NF-κB signaling pathway.

Autophagy in motor neuron diseases

Motor neuron diseases (MNDs) are a wide group of neurodegenerative disorders characterized by the degeneration of a specific neuronal type located in the central nervous system, the motor neuron (MN). There are two main types of MNs, spinal and cortical MNs and depending on the type of MND, one or both types are affected. Cortical MNs innervate spinal MNs and these control a variety of cellular targets, being skeletal muscle their main one which is also affected in MNDs. A correct functionality of autophagy is necessary for the survival of all cellular types and it is particularly crucial for neurons, given their postmitotic and highly specialized nature. Numerous studies have identified alterations of autophagy activity in multiple MNDs. The scientific community has been particularly prolific in reporting the role that autophagy plays in the most common adult MND, amyotrophic lateral sclerosis, although many studies have started to identify physiological and pathological functions of this catabolic system in other MNDs, such as spinal muscular atrophy and spinal and bulbar muscular atrophy. The degradation of selective cargo by autophagy and how this process is altered upon the presence of MND-causing mutations is currently also a matter of intense investigation, particularly regarding the selective autophagic clearance of mitochondria. Thorough reviews on this field have been recently published. This chapter will cover the current knowledge on the functionality of autophagy and lysosomal homeostasis in the main MNDs and other autophagy-related topics in the MND field that have risen special interest in the research community.

Insulin-like growth factor 1 signaling in motor neuron and polyglutamine diseases: From molecular pathogenesis to therapeutic perspectives

The pleiotropic peptide insulin-like growth factor 1 (IGF-I) regulates human body homeostasis and cell growth. IGF-I activates two major signaling pathways, namely phosphoinositide-3-kinase (PI3K)/protein kinase B (PKB/Akt) and Ras/extracellular signal-regulated kinase (ERK), which contribute to brain development, metabolism and function as well as to neuronal maintenance and survival. In this review, we discuss the general and tissue-specific effects of the IGF-I pathways. In addition, we present a comprehensive overview examining the role of IGF-I in neurodegenerative diseases, such as spinal and muscular atrophy, amyotrophic lateral sclerosis, and polyglutamine diseases. In each disease, we analyze the disturbances of the IGF-I pathway, the modification of the disease protein by IGF-I signaling, and the therapeutic strategies based on the use of IGF-I developed to date. Lastly, we highlight present and future considerations in the use of IGF-I for the treatment of these disorders.

Loganin prevents chronic constriction injury-provoked neuropathic pain by reducing TNF-α/IL-1β-mediated NF-κB activation and Schwann cell demyelination

BACKGROUND

Peripheral nerve injury can produce chronic and ultimately neuropathic pain. The chronic constriction injury (CCI) model has provided a deeper understanding of nociception and chronic pain. Loganin is a well-known herbal medicine with glucose-lowering action and neuroprotective activity.

PURPOSE

This study investigated the molecular mechanisms by which loganin reduced CCI-induced neuropathic pain.

METHODS

Sprague-Dawley rats were randomly divided into four groups: sham, sham+loganin, CCI and CCI+loganin. Loganin (1 or 5 mg/kg/day) was injected intraperitoneally once daily for 14 days, starting the day after CCI. For behavioral testing, mechanical and thermal responses were assessed before surgery and on d1, d3, d7 and d14 after surgery. Sciatic nerves (SNs) were collected to measure proinflammatory cytokines. Proximal and distal SNs were collected separately for Western blotting and immunofluorescence studies.

RESULTS

Thermal hyperalgesia and mechanical allodynia were reduced in the loganin-treated group as compared to the CCI group. Loganin (5 mg/kg/day) prevented CCI from inducing proinflammatory cytokines (TNF-α, IL-1β), inflammatory proteins (TNF-α, IL-1β, pNFκB, pIκB/IκB, iNOS) and receptor (TNFR1, IL-1R), adaptor protein (TRAF2) of TNF-α, and Schwann cell demyelination and axonal damage. Loganin also blocked IκB phosphorylation (p-IκB). Double immunofluorescent staining further demonstrated that pNFκB/pIκB protein was reduced by loganin in Schwann cells on d7 after CCI. In the distal stumps of injured SN, Schwann cell demyelination was correlated with pain behaviors in CCI rats.

CONCLUSION

Our findings indicate that loganin improves CCI-induced neuroinflammation and pain behavior by downregulating TNF-α/IL-1β-dependent NF-κB activation.

Drug treatment for spinal muscular atrophy types II and III

BACKGROUND

Spinal muscular atrophy (SMA) is caused by a homozygous deletion of the survival motor neuron 1 (SMN1) gene on chromosome 5, or a heterozygous deletion in combination with a (point) mutation in the second SMN1 allele. This results in degeneration of anterior horn cells, which leads to progressive muscle weakness. Children with SMA type II do not develop the ability to walk without support and have a shortened life expectancy, whereas children with SMA type III develop the ability to walk and have a normal life expectancy. This is an update of a review first published in 2009 and previously updated in 2011.

OBJECTIVES

To evaluate if drug treatment is able to slow or arrest the disease progression of SMA types II and III, and to assess if such therapy can be given safely.

SEARCH METHODS

We searched the Cochrane Neuromuscular Specialised Register, CENTRAL, MEDLINE, Embase, and ISI Web of Science conference proceedings in October 2018. In October 2018, we also searched two trials registries to identify unpublished trials.

SELECTION CRITERIA

We sought all randomised or quasi-randomised trials that examined the efficacy of drug treatment for SMA types II and III. Participants had to fulfil the clinical criteria and have a homozygous deletion or hemizygous deletion in combination with a point mutation in the second allele of the SMN1 gene (5q11.2-13.2) confirmed by genetic analysis. The primary outcome measure was change in disability score within one year after the onset of treatment. Secondary outcome measures within one year after the onset of treatment were change in muscle strength, ability to stand or walk, change in quality of life, time from the start of treatment until death or full-time ventilation and adverse events attributable to treatment during the trial period. Treatment strategies involving SMN1-replacement with viral vectors are out of the scope of this review, but a summary is given in Appendix 1. Drug treatment for SMA type I is the topic of a separate Cochrane Review.

DATA COLLECTION AND ANALYSIS

We followed standard Cochrane methodology.

MAIN RESULTS

The review authors found 10 randomised, placebo-controlled trials of treatments for SMA types II and III for inclusion in this review, with 717 participants. We added four of the trials at this update. The trials investigated creatine (55 participants), gabapentin (84 participants), hydroxyurea (57 participants), nusinersen (126 participants), olesoxime (165 participants), phenylbutyrate (107 participants), somatotropin (20 participants), thyrotropin-releasing hormone (TRH) (nine participants), valproic acid (33 participants), and combination therapy with valproic acid and acetyl-L-carnitine (ALC) (61 participants). Treatment duration was from three to 24 months. None of the studies investigated the same treatment and none was completely free of bias. All studies had adequate blinding, sequence generation and reporting of primary outcomes. Based on moderate-certainty evidence, intrathecal nusinersen improved motor function (disability) in children with SMA type II, with a 3.7-point improvement in the nusinersen group on the Hammersmith Functional Motor Scale Expanded (HFMSE; range of possible scores 0 to 66), compared to a 1.9-point decline on the HFMSE in the sham procedure group (P < 0.01; n = 126). On all motor function scales used, higher scores indicate better function. Based on moderate-certainty evidence from two studies, the following interventions had no clinically important effect on motor function scores in SMA types II or III (or both) in comparison to placebo: creatine (median change 1 higher, 95% confidence interval (CI) -1 to 2; on the Gross Motor Function Measure (GMFM), scale 0 to 264; n = 40); and combination therapy with valproic acid and carnitine (mean difference (MD) 0.64, 95% CI -1.1 to 2.38; on the Modified Hammersmith Functional Motor Scale (MHFMS), scale 0 to 40; n = 61). Based on low-certainty evidence from other single studies, the following interventions had no clinically important effect on motor function scores in SMA types II or III (or both) in comparison to placebo: gabapentin (median change 0 in the gabapentin group and -2 in the placebo group on the SMA Functional Rating Scale (SMAFRS), scale 0 to 50; n = 66); hydroxyurea (MD -1.88, 95% CI -3.89 to 0.13 on the GMFM, scale 0 to 264; n = 57), phenylbutyrate (MD -0.13, 95% CI -0.84 to 0.58 on the Hammersmith Functional Motor Scale (HFMS) scale 0 to 40; n = 90) and monotherapy of valproic acid (MD 0.06, 95% CI -1.32 to 1.44 on SMAFRS, scale 0 to 50; n = 31). Very low-certainty evidence suggested that the following interventions had little or no effect on motor function: olesoxime (MD 2, 95% -0.25 to 4.25 on the Motor Function Measure (MFM) D1 + D2, scale 0 to 75; n = 160) and somatotropin (median change at 3 months 0.25 higher, 95% CI -1 to 2.5 on the HFMSE, scale 0 to 66; n = 19). One small TRH trial did not report effects on motor function and the certainty of evidence for other outcomes from this trial were low or very low. Results of nine completed trials investigating 4-aminopyridine, acetyl-L-carnitine, CK-2127107, hydroxyurea, pyridostigmine, riluzole, RO6885247/RG7800, salbutamol and valproic acid were awaited and not available for analysis at the time of writing. Various trials and studies investigating treatment strategies other than nusinersen (e.g. SMN2-augmentation by small molecules), are currently ongoing.

AUTHORS' CONCLUSIONS

Nusinersen improves motor function in SMA type II, based on moderate-certainty evidence. Creatine, gabapentin, hydroxyurea, phenylbutyrate, valproic acid and the combination of valproic acid and ALC probably have no clinically important effect on motor function in SMA types II or III (or both) based on low-certainty evidence, and olesoxime and somatropin may also have little to no clinically important effect but evidence was of very low-certainty. One trial of TRH did not measure motor function.

Drug treatment for spinal muscular atrophy type I

BACKGROUND

Spinal muscular atrophy (SMA) is caused by a homozygous deletion of the survival motor neuron 1 (SMN1) gene on chromosome 5, or a heterozygous deletion in combination with a point mutation in the second SMN1 allele. This results in degeneration of anterior horn cells, which leads to progressive muscle weakness. By definition, children with SMA type I are never able to sit without support and usually die or become ventilator dependent before the age of two years. There have until very recently been no drug treatments to influence the course of SMA. We undertook this updated review to evaluate new evidence on emerging treatments for SMA type I. The review was first published in 2009 and previously updated in 2011.

OBJECTIVES

To assess the efficacy and safety of any drug therapy designed to slow or arrest progression of spinal muscular atrophy (SMA) type I.

SEARCH METHODS

We searched the Cochrane Neuromuscular Specialised Register, CENTRAL, MEDLINE, Embase, and ISI Web of Science conference proceedings in October 2018. We also searched two trials registries to identify unpublished trials (October 2018).

SELECTION CRITERIA

We sought all randomised controlled trials (RCTs) or quasi-RCTs that examined the efficacy of drug treatment for SMA type I. Included participants had to fulfil clinical criteria and have a genetically confirmed deletion or mutation of the SMN1 gene (5q11.2-13.2). The primary outcome measure was age at death or full-time ventilation. Secondary outcome measures were acquisition of motor milestones, i.e. head control, rolling, sitting or standing, motor milestone response on disability scores within one year after the onset of treatment, and adverse events and serious adverse events attributable to treatment during the trial period. Treatment strategies involving SMN1 gene replacement with viral vectors are out of the scope of this review.

DATA COLLECTION AND ANALYSIS

We followed standard Cochrane methodology.

MAIN RESULTS

We identified two RCTs: one trial of intrathecal nusinersen in comparison to a sham (control) procedure in 121 randomised infants with SMA type I, which was newly included at this update, and one small trial comparing riluzole treatment to placebo in 10 children with SMA type I. The RCT of intrathecally-injected nusinersen was stopped early for efficacy (based on a predefined Hammersmith Infant Neurological Examination-Section 2 (HINE-2) response). At the interim analyses after 183 days of treatment, 41% (21/51) of nusinersen-treated infants showed a predefined improvement on HINE-2, compared to 0% (0/27) of participants in the control group. This trial was largely at low risk of bias. Final analyses (ranging from 6 months to 13 months of treatment), showed that fewer participants died or required full-time ventilation (defined as more than 16 hours daily for 21 days or more) in the nusinersen-treated group than the control group (hazard ratio (HR) 0.53, 95% confidence interval (CI) 0.32 to 0.89; N = 121; a 47% lower risk; moderate-certainty evidence). A proportion of infants in the nusinersen group and none of 37 infants in the control group achieved motor milestones: 37/73 nusinersen-treated infants (51%) achieved a motor milestone response on HINE-2 (risk ratio (RR) 38.51, 95% CI 2.43 to 610.14; N = 110; moderate-certainty evidence); 16/73 achieved head control (RR 16.95, 95% CI 1.04 to 274.84; moderate-certainty evidence); 6/73 achieved independent sitting (RR 6.68, 95% CI 0.39 to 115.38; moderate-certainty evidence); 7/73 achieved rolling over (RR 7.70, 95% CI 0.45 to 131.29); and 1/73 achieved standing (RR 1.54, 95% CI 0.06 to 36.92; moderate-certainty evidence). Seventy-one per cent of nusinersen-treated infants versus 3% of infants in the control group were responders on the Children's Hospital of Philadelphia Infant Test of Neuromuscular Disorders (CHOP INTEND) measure of motor disability (RR 26.36, 95% CI 3.79 to 183.18; N = 110; moderate-certainty evidence). Adverse events and serious adverse events occurred in the majority of infants but were no more frequent in the nusinersen-treated group than the control group (RR 0.99, 95% CI 0.92 to 1.05 and RR 0.70, 95% CI 0.55 to 0.89, respectively; N = 121; moderate-certainty evidence). In the riluzole trial, three of seven children treated with riluzole were still alive at the ages of 30, 48, and 64 months, whereas all three children in the placebo group died. None of the children in the riluzole or placebo group developed the ability to sit, which was the only milestone reported. There were no adverse effects. The certainty of the evidence for all measured outcomes from this study was very low, because the study was too small to detect or rule out an effect, and had serious limitations, including baseline differences. This trial was stopped prematurely because the pharmaceutical company withdrew funding. Various trials and studies investigating treatment strategies other than nusinersen, such as SMN2 augmentation by small molecules, are ongoing.

AUTHORS' CONCLUSIONS

Based on the very limited evidence currently available regarding drug treatments for SMA type 1, intrathecal nusinersen probably prolongs ventilation-free and overall survival in infants with SMA type I. It is also probable that a greater proportion of infants treated with nusinersen than with a sham procedure achieve motor milestones and can be classed as responders to treatment on clinical assessments (HINE-2 and CHOP INTEND). The proportion of children experiencing adverse events and serious adverse events on nusinersen is no higher with nusinersen treatment than with a sham procedure, based on evidence of moderate certainty. It is uncertain whether riluzole has any effect in patients with SMA type I, based on the limited available evidence. Future trials could provide more high-certainty, longer-term evidence to confirm this result, or focus on comparing new treatments to nusinersen or evaluate them as an add-on therapy to nusinersen.

Mechanisms of exercise-induced survival motor neuron expression in the skeletal muscle of spinal muscular atrophy-like mice

Key points

Spinal muscular atrophy (SMA) is a health‐ and life‐limiting neuromuscular disorder caused by a deficiency in survival motor neuron (SMN) protein.

While historically considered a motor neuron disease, current understanding of SMA emphasizes its systemic nature, which requires addressing affected peripheral tissues such as skeletal muscle in particular.

Chronic physical activity is beneficial for SMA patients, but the cellular and molecular mechanisms of exercise biology are largely undefined in SMA.

After a single bout of exercise, canonical responses such as skeletal muscle AMP‐activated protein kinase (AMPK), p38 mitogen‐activated protein kinase (p38) and peroxisome proliferator‐activated receptor γ coactivator 1α (PGC‐1α) activation were preserved in SMA‐like Smn^2B/− animals. Furthermore, molecules involved in SMN transcription were also altered following physical activity. Collectively, these changes were coincident with an increase in full‐length SMN transcription and corrective SMN pre‐mRNA splicing.

This study advances understanding of the exercise biology of SMA and highlights the AMPK–p38–PGC‐1α axis as a potential regulator of SMN expression in muscle.

Abstract

Chronic physical activity is safe and effective in spinal muscular atrophy (SMA) patients, but the underlying cellular events that drive physiological adaptations are undefined. We examined the effects of a single bout of exercise on molecular mechanisms associated with adaptive remodelling in the skeletal muscle of Smn^2B/− SMA‐like mice. Skeletal muscles were collected from healthy Smn^2B/+ mice and Smn^2B/− littermates at pre‐ (postnatal day (P) 9), early‐ (P13) and late‐ (P21) symptomatic stages to characterize SMA disease progression. Muscles were also collected from Smn^2B/− animals exercised to fatigue on a motorized treadmill. Intracellular signalling and gene expression were examined using western blotting, confocal immunofluorescence microscopy, real‐time quantitative PCR and endpoint PCR assays. Basal skeletal muscle AMP‐activated protein kinase (AMPK) and p38 mitogen‐activated protein kinase (p38) expression and activity were not affected by SMA‐like conditions. Canonical exercise responses such as AMPK, p38 and peroxisome proliferator‐activated receptor γ coactivator‐1α (PGC‐1α) activation were observed following a bout of exercise in Smn^2B/− animals. Furthermore, molecules involved in survival motor neuron (SMN) transcription, including protein kinase B (AKT) and extracellular signal‐regulated kinases (ERK)/ETS‐like gene 1 (ELK1), were altered following physical activity. Acute exercise was also able to mitigate aberrant proteolytic signalling in the skeletal muscle of Smn^2B/− mice. Collectively, these changes were coincident with an exercise‐evoked increase in full‐length SMN mRNA expression. This study advances our understanding of the exercise biology of SMA and highlights the AMPK–p38–PGC‐1α axis as a potential regulator of SMN expression alongside AKT and ERK/ELK1 signalling.

Spinal muscular atrophy (SMA) is a health‐ and life‐limiting neuromuscular disorder caused by a deficiency in survival motor neuron (SMN) protein.

While historically considered a motor neuron disease, current understanding of SMA emphasizes its systemic nature, which requires addressing affected peripheral tissues such as skeletal muscle in particular.

Chronic physical activity is beneficial for SMA patients, but the cellular and molecular mechanisms of exercise biology are largely undefined in SMA.

After a single bout of exercise, canonical responses such as skeletal muscle AMP‐activated protein kinase (AMPK), p38 mitogen‐activated protein kinase (p38) and peroxisome proliferator‐activated receptor γ coactivator 1α (PGC‐1α) activation were preserved in SMA‐like Smn^2B/− animals. Furthermore, molecules involved in SMN transcription were also altered following physical activity. Collectively, these changes were coincident with an increase in full‐length SMN transcription and corrective SMN pre‐mRNA splicing.

This study advances understanding of the exercise biology of SMA and highlights the AMPK–p38–PGC‐1α axis as a potential regulator of SMN expression in muscle.

2-Iodo-4'-Methoxychalcone Attenuates Methylglyoxal-Induced Neurotoxicity by Activation of GLP-1 Receptor and Enhancement of Neurotrophic Signal, Antioxidant Defense and Glyoxalase Pathway

Methylglyoxal (MG) acts as a reactive precursor of advanced glycation end products (AGEs). This compound is often connected with pathologies such as diabetes, neurodegenerative processes and diseases of aging. 2-iodo-4'-methoxychalcone (CHA79), a synthetic halogen-containing chalcone derivative, has been reported its anti-diabetic activity. This study aims to investigate the potential protective capability of CHA79 against MG-mediated neurotoxicity in SH-SY5Y cells. Results indicated CHA79 increased viability of cells and attenuated the rate of apoptosis in MG-exposed SH-SY5Y. CHA79 up-regulated expression of anti-apoptotic protein (Bcl-2) and down-regulated apoptotic proteins (Bax, cytochrome c, caspase-3, caspase-9). Moreover, CHA79 significantly up-regulated expression of neurotrophic factors, including glucagon-like peptide-1 receptor (GLP-1R), brain derived neurotrophic factor (BDNF), p75NTR, p-TrkB, p-Akt, p-GK-3β and p-CREB. CHA79 attenuated MG-induced ROS production and enhanced the antioxidant defense including nuclear factor erythroid 2-related factor 2 (Nrf2), HO-1, SOD and GSH. Furthermore, CHA79 attenuated MG-induced reduction of glyoxalase-1 (GLO-1), a vital enzyme on removing AGE precursors. In conclusion, CHA79 is the first novel synthetic chalcone possessing the GLP-1R and GLO-1 activating properties. CHA 79 also exhibits neuroprotective effects against MG toxicity by enhancing neurotrophic signal, antioxidant defense and anti-apoptosis pathway.

Loganin Attenuates Osteoarthritis in Rats by Inhibiting IL-1β-Induced Catabolism and Apoptosis in Chondrocytes Via Regulation of Phosphatidylinositol 3-Kinases (PI3K)/Akt

Background

Chondrocyte apoptosis and catabolism are 2 major factors that contribute to the progression of osteoarthritis (OA). Loganin, an iridoid glycoside present in several herbs, including Flos lonicerae, Cornus mas L, and Strychnos nux vomica, is a valuable medication with anti-inflammatory and anti-apoptotic effects. Our study examines these effects and explores the potential benefits of loganin in the OA treatment.

Material/Methods

To clarify the roles of loganin in OA and its specific signaling pathway, chondrocytes were administrated with IL-1β and supplemented with or without LY294002 (a classic PI3K/Akt inhibitor). The apoptotic level, catabolic factors (MMP-3 and MMP-13 and ADAMTS-4 and ADAMTS-5), extracellular matrix (ECM) degradation, and activation of the PI3K/Akt pathway were evaluated using western blotting, PCR, and an immunofluorescent assay. The degenerative condition of the cartilage was evaluated using the Safranin O assay in vivo. The expression of cleaved-caspase-3 (C-caspase-3) was measured using immunochemistry.

Results

The data suggested that loganin suppressed the apoptotic level, reduced the release of catabolic enzymes, and decreased the ECM degradation of IL-1β-induced chondrocytes. However, suppressing PI3K/Akt signaling using LY294002 alleviated the therapeutic effects of loganin in chondrocytes. Our in vivo experiment showed that loganin partially attenuated cartilage degradation while inhibiting the apoptotic level.

Conclusions

This work revealed that loganin treatment attenuated IL-1β-treated apoptosis and ECM catabolism in rat chondrocytes via regulation of the PI3K/Akt signaling, revealing that loganin is a potentially useful treatment for OA.

Naringenin, a dietary flavanone, enhances insulin-like growth factor 1 receptor-mediated antioxidant defense and attenuates methylglyoxal-induced neurite damage and apoptotic death

Objectives: Recent studies revealed the neuroprotective effects of naringenin (NGEN), a common dietary bioflavonoid contained in citrus fruits. However, there are limited data on its protection against methylglyoxal (MG), the most potent precursor of advanced glycation end-products. The present study was to investigate the protection of NGEN on MG-induced neurotoxicity and the involvement of insulin-like growth factor 1 receptor (IGF-1R) signaling. Methods: NSC34 motor neuron-like cells was used. Cell viability was measured by MTT assay. Protein expressions were analyzed by western blots. Morphological changes of neurites were observed by an inverted microscope. Reactive oxygen species (ROS) production and apoptotic cell numbers were measured by flow cytometer. Glutathione (GSH) level and superoxide dismutase (SOD) activity were measured by ELISA. Results: >NGEN attenuated ROS production and increased GSH level, SOD activity and nuclear factor erythroid 2-related factor 2 (Nrf2) nuclear expression in MG-treated NSC34 cells. NGEN also increased neurite length and enhanced IGF-1R and p-Akt in MG-treated NSC34 cells. Furthermore, NGEN attenuated MG-induced apoptotic death accompanied with down-regulation of cleaved-poly (ADP-ribose) polymerase (PARP) and up-regulation of B-cell lymphoma-2 (Bcl-2). However, AG1024, an IGF-1R antagonist, attenuated the anti-oxidative and anti-apoptotic effects of NGEN in MG-treated cells. Discussion: The present results demonstrated that NGEN decreased neuronal apoptosis and improved antioxidant defense in MG-treated NSC34 cells. Moreover, IGF-1R-mediated antioxidant defense plays an important role in this protective mechanism. These findings suggest the potential benefits of NGEN on the prevention of MG-induced or diabetes/hyperglycemia-related neurotoxicity. In vivo studies are needed for further confirmation on NGEN-mediated neuroprotection.

Protective effects of Liuwei dihuang water extracts on diabetic muscle atrophy

BACKGROUND

Liuwei dihuang (LWDH), a widely used traditional Chinese herbal medicine, has been noticed for its potential on the improvement of diabetic complications including diabetic nephropathy and diabetic encephalopathy. However, whether LWDH can improve the effects of diabetic skeletal muscle atrophy has not yet been reported.

PURPOSE

The present study aimed to investigate the protective effects and mechanisms of the water extract of Liuwei dihuang (LWDH-WE) on skeletal muscle in cellular and animal models of diabetic muscle atrophy.

STUDY DESIGN

The muscle protective effects of LWDH-WE on diabetic muscle atrophy and weakness were examined in methylglyoxal (MG)-treated C2C12 myotubes and streptozotocin (STZ)-treated C57BL/6 mice, respectively.

METHODS

C2C12 myoblasts were differentiated by differentiation medium to form myotube structures. C2C12 myotubes were pre-treated with LWDH-WE 1 h before MG treatment. Diabetic mice were induced by single intraperitoneal injection of STZ (150 mg/kg) in C57BL/6 mice. Cell viability was determined by MTT and LDH assays. Protein expressions were detected by western blots. Morphological changes of cells were observed by an inverted microscope. Mitochondria membrane potential and reactive oxygen species (ROS) production were measured by flow cytometry. Muscle strength was evaluated by measuring grip strength of mice.

RESULTS

In C2C12 myotubes, LWDH-WE attenuated MG-induced cellular death and oxidative damage accompanied with improving mitochondrial membrane potential, inhibiting NADPH oxidase (Nox) activation, and ROS production. Moreover, LWDH-WE could attenuate MG-induced atrophy of C2C12 myotubes accompanied with regulating protein synthesis (IGF-1R, Akt, mTOR) and protein degradation (FoxO3a, atrogin-1, MuRF-1) signals. In STZ-induced diabetic mice, LWDH-WE improved body weight and skeletal muscle mass of mice. LWDH-WE also enhanced muscle strength of STZ-induced diabetic mice. Furthermore, LWDH-WE enhanced the improvement of insulin on gastrocnemius muscle mass and grip strength in STZ-treated mice.

CONCLUSION

LWDH-WE possesses skeletal muscle protection via reducing oxidative damage and regulating protein synthesis and degradation pathways in MG-induced atrophy of C2C12 myotubes. We also reveal the novel protection of LWDH-WE against STZ-induced reduction of muscle mass and muscle strength in mice.

Elucidation of the Intestinal Absorption Mechanism of Loganin in the Human Intestinal Caco-2 Cell Model

Loganin, iridoid glycosides, is the main bioactive ingredients in the plant Strychnos nux-vomica L. and demonstrates various pharmacological effects, though poor oral bioavailability in rats. In this study, the intestinal absorption mechanism of loganin was investigated using the human intestinal Caco-2 cell monolayer model in both the apical-to-basolateral (A-B) and the basolateral-to-apical (B-A) direction; additionally, transport characteristics were systematically investigated at different concentrations, pHs, temperatures, and potential transporters. The absorption permeability (PappAB) of loganin, which ranged from 12.17 to 14.78 × 10-6cm/s, was high at four tested concentrations (5, 20, 40, and 80μM), while the major permeation mechanism of loganin was found to be passive diffusion with active efflux mediated by multidrug resistance-associated protein (MRP) and breast cancer resistance protein (BCRP). In addition, it was found that loganin was not the substrate of efflux transporter P-glycoprotein (P-gp) since the selective inhibitor (verapamil) of the efflux transporter exhibited little effects on the transport of loganin in the human intestinal Caco-2 cells. Meanwhile, transport from the apical to the basolateral side increased 2.09-fold after addition of a MRP inhibitor and 2.32-fold after addition of a BCRP inhibitor. In summary, our results clearly demonstrate, for the first time, a good permeability of loganin in the human intestinal Caco-2 cell model and elucidate, in detail, the intestinal absorption mechanism and the effects of transporters on iridoid glycosides compounds.

The novel protective effects of loganin against 1-methyl-4-phenylpyridinium-induced neurotoxicity: Enhancement of neurotrophic signaling, activation of IGF-1R/GLP-1R, and inhibition of RhoA/ROCK pathway

Loganin, a major iridoid glycoside obtained from fruits of Cornus officinalis, possesses anti-inflammatory, antitumor, antidiabetic, and osteoporosis prevention effects. Loganin has been linked to neuroprotection in several models of neurodegeneration, including Parkinson's disease (PD). However, mechanisms underlying the neuroprotective effects of loganin are still mostly unknown. Here, we demonstrated the protective effects of loganin against PD mimetic toxin 1-methyl-4-phenylpyridinium (MPP⁺ ) and the important roles of insulin-like growth factor 1 receptor (IGF-1R) and glucagon-like peptide 1 receptor (GLP-1R) in the neuroprotective mechanisms of loganin. In primary mesencephalic neuronal cultures treated with or without MPP⁺ , loganin up-regulated expressions of neurotrophic signals including IGF-1R, GLP-1R, p-Akt, BDNF, and tyrosine hydroxylase. Loganin protected against MPP⁺ -induced apoptosis by up-regulating antiapoptotic protein and down-regulating proapoptotic protein. Moreover, loganin attenuated MPP⁺ -induced neurite damage via up-regulation of GAP43 and down-regulation of membrane-RhoA/ROCK2/p-LIMK/p-cofilin. Loganin also attenuated MPP⁺ -induced reactive oxygen species (ROS) production. However, both AG1024, an IGF-1R antagonist, and exendin 9-39, a GLP-1R antagonist, attenuated the protective effects of loganin on MPP⁺ -induced cytotoxicity, apoptosis, neurite length decrease, and ROS production. Our results suggest that loganin attenuates MPP⁺ -induced apoptotic death, neurite damage, and oxidative stress through enhancement of neurotrophic signaling, activation of IGF-1R/GLP-1R, and inhibition of RhoA/ROCK pathway, providing the evidence that loganin possesses novel neuroprotective effects.

Scabiosa Genus: A Rich Source of Bioactive Metabolites

The genus Scabiosa (family Caprifoliaceae) is considered large (618 scientific plant names of species) although only 62 have accepted Latin binominal names. The majority of the Scabiosa species are widely distributed in the Mediterranean region and some Scabiosa species are used in traditional medicine systems. For instance, Scabiosa columbaria L. is used traditionally against diphtheria while S. comosa Fisch. Ex Roem. and Schult. is used in Mongolian and Tibetan traditional medical settings to treat liver diseases. The richness of Scabiosa species in secondary metabolites such as iridoids, flavonoids and pentacyclic triterpenoids may contribute to its use in folk medicine. Details on the most recent and relevant pharmacological in vivo studies on the bioactive secondary metabolites isolated from Scabiosa species will be summarized and thoroughly discussed.

Molecular Factors Involved in Spinal Muscular Atrophy Pathways as Possible Disease-modifying Candidates

Spinal Muscular Atrophy (SMA) is a neuromuscular disorder caused by mutations in the SMN1 gene. Being a monogenic disease, it is characterized by high clinical heterogeneity. Variations in penetrance and severity of symptoms, as well as clinical discrepancies between affected family members can result from modifier genes influence on disease manifestation. SMN2 gene copy number is known to be the main phenotype modifier and there is growing evidence of additional factors contributing to SMA severity. Potential modifiers of spinal muscular atrophy can be found among the wide variety of different factors, such as multiple proteins interacting with SMN or promoting motor neuron survival, epigenetic modifications, transcriptional or splicing factors influencing SMN2 expression. Study of these factors enables to reveal mechanisms underlying SMA pathology and can have pronounced clinical application.

The increase in fiber size in male rat gastrocnemius after chronic central leptin infusion is related to activation of insulin signaling

Insulin potentiates leptin effects on muscle accrual and glucose homeostasis. However, the relationship between leptin's central effects on peripheral insulin sensitivity and the associated structural changes remain unclear. We hypothesized that central leptin infusion modifies muscle size through activation of insulin signaling. Muscle insulin signaling, enzymes of fatty acid metabolism, mitochondrial respiratory chain complexes, proliferating cell nuclear antigen (PCNA) and fiber area were analyzed in the gastrocnemius of chronic central infused (L), pair-fed (PF) and control rats. PCNA-positive nuclei, fiber area, GLUT4 and glycogen levels and activation of Akt and mechanistic target of rapamycin were increased in L, with no changes in PF. Acetyl-CoA carboxylase-β mRNA levels and non-esterified fatty acid and triglyceride content were reduced and carnitine palmitoyltransferase-1b expression and mitochondrial complexes augmented in L. These results suggest that leptin promotes an increase in muscle size associated with improved insulin signaling favored by lipid profile.

Blocking p62-dependent SMN degradation ameliorates spinal muscular atrophy disease phenotypes

Spinal muscular atrophy (SMA), a degenerative motor neuron (MN) disease, caused by loss of functional survival of motor neuron (SMN) protein due to SMN1 gene mutations, is a leading cause of infant mortality. Increasing SMN levels ameliorates the disease phenotype and is unanimously accepted as a therapeutic approach for patients with SMA. The ubiquitin/proteasome system is known to regulate SMN protein levels; however, whether autophagy controls SMN levels remains poorly explored. Here, we show that SMN protein is degraded by autophagy. Pharmacological and genetic inhibition of autophagy increases SMN levels, while induction of autophagy decreases these levels. SMN degradation occurs via its interaction with the autophagy adapter p62 (also known as SQSTM1). We also show that SMA neurons display reduced autophagosome clearance, increased p62 and ubiquitinated proteins levels, and hyperactivated mTORC1 signaling. Importantly, reducing p62 levels markedly increases SMN and its binding partner gemin2, promotes MN survival, and extends lifespan in fly and mouse SMA models, revealing p62 as a potential new therapeutic target for the treatment of SMA.

Interventions Targeting Glucocorticoid-Krüppel-like Factor 15-Branched-Chain Amino Acid Signaling Improve Disease Phenotypes in Spinal Muscular Atrophy Mice

The circadian glucocorticoid-Krüppel-like factor 15-branched-chain amino acid (GC-KLF15-BCAA) signaling pathway is a key regulatory axis in muscle, whose imbalance has wide-reaching effects on metabolic homeostasis. Spinal muscular atrophy (SMA) is a neuromuscular disorder also characterized by intrinsic muscle pathologies, metabolic abnormalities and disrupted sleep patterns, which can influence or be influenced by circadian regulatory networks that control behavioral and metabolic rhythms. We therefore set out to investigate the contribution of the GC-KLF15-BCAA pathway in SMA pathophysiology of Taiwanese Smn^−/−;SMN2 and Smn^2B/− mouse models. We thus uncover substantial dysregulation of GC-KLF15-BCAA diurnal rhythmicity in serum, skeletal muscle and metabolic tissues of SMA mice. Importantly, modulating the components of the GC-KLF15-BCAA pathway via pharmacological (prednisolone), genetic (muscle-specific Klf15 overexpression) and dietary (BCAA supplementation) interventions significantly improves disease phenotypes in SMA mice. Our study highlights the GC-KLF15-BCAA pathway as a contributor to SMA pathogenesis and provides several treatment avenues to alleviate peripheral manifestations of the disease. The therapeutic potential of targeting metabolic perturbations by diet and commercially available drugs could have a broader implementation across other neuromuscular and metabolic disorders characterized by altered GC-KLF15-BCAA signaling.

•

SMA is a neuromuscular disease characterized by motoneuron loss, muscle abnormalities and metabolic perturbations.

•

The regulatory GC-KLF15-BCAA pathway is dysregulated in serum and skeletal muscle of SMA mice during disease progression.

•

Modulating GC-KLF15-BCAA signaling by pharmacological, dietary and genetic interventions improves phenotype of SMA mice.

Spinal muscular atrophy (SMA) is a devastating and debilitating childhood genetic disease. Although nerve cells are mainly affected, muscle is also severely impacted. The normal communication between the glucocorticoid (GC) hormone, the protein KLF15 and the dietary branched-chain amino acids (BCAAs) maintains muscle and whole-body health. In this study, we identified an abnormal activity of GC-KLF15- BCAA in blood and muscle of SMA mice. Importantly, targeting GC-KLF15-BCAA activity with an existing drug or a specific diet improved disease progression in SMA mice. Our research uncovers GCs, KLF15 and BCAAs as therapeutic targets to ameliorate SMA muscle and whole-body health.

Loganic Acid Methyltransferase: Insights into the Specificity of Methylation on an Iridoid Glycoside

Loganin is an iridoid glycoside of interest as both an intermediate in the biosynthesis of indole alkaloids in plants and as a bioactive compound itself. Loganic acid methyltransferase catalyzes the methylation of a monoterpenoid glycoside precursor to produce loganin and demonstrates stereospecificity for the (6S,7R) substrate. We have biochemically characterized this biocatalyst and elucidated the basis for its strict substrate specificity. These studies could help facilitate the design of new classes of monoterpenoid indole alkaloids of pharmaceutical interest.

Spinal muscular atrophy: antisense oligonucleotide therapy opens the door to an integrated therapeutic landscape

Spinal muscular atrophy (SMA) is a devastating neuromuscular disorder characterized by loss of spinal cord motor neurons, muscle atrophy and infantile death or severe disability. It is caused by severe reduction of the ubiquitously expressed survival motor neuron (SMN) protein, owing to loss of the SMN1 gene. This would be completely incompatible with survival without the presence of a quasi-identical duplicated gene, SMN2, specific to humans. SMN2 harbours a silent point mutation that favours the production of transcripts lacking exon 7 and a rapidly degraded non-functional SMNΔ7 protein, but from which functional full length SMN protein is produced at very low levels (∼10%). Since the seminal discovery of the SMA-causing gene in 1995, research has focused on the development of various SMN replacement strategies culminating, in December 2016, in the approval of the first precise molecularly targeted therapy for SMA (nusinersen), and a pivotal proof of principle that therapeutic antisense oligonucleotide (ASO) treatment can effectively target the central nervous system (CNS) to treat neurological and neuromuscular disease. Nusinersen is a steric block ASO that binds the SMN2 messenger RNA and promotes exon 7 inclusion and thus increases full length SMN expression. Here, we consider the implications of this therapeutic landmark for SMA therapeutics and discuss how future developments will need to address the challenges of delivering ASO therapies to the CNS, with appropriate efficiency and activity, and how SMN-based therapy should be used in combination with complementary strategies to provide an integrated approach to treat CNS and peripheral pathologies in SMA.

The water extract of Liuwei dihuang possesses multi-protective properties on neurons and muscle tissue against deficiency of survival motor neuron protein

BACKGROUND

Deficiency of survival motor neuron (SMN) protein, which is encoded by the SMN1 and SMN2 genes, induces widespread splicing defects mainly in spinal motor neurons, and leads to spinal muscular atrophy (SMA). Currently, there is no effective treatment for SMA. Liuwei dihuang (LWDH), a traditional Chinese herbal formula, possesses multiple therapeutic benefits against various diseases via modulation of the nervous, immune and endocrine systems. Previously, we demonstrated water extract of LWDH (LWDH-WE) protects dopaminergic neurons and improves motor activity in models of Parkinson's disease.

PURPOSE

This study aimed to investigate the potential protection of LWDH-WE on SMN deficiency-induced neurodegeneration and muscle weakness.

STUDY DESIGN

The effects of LWDH-WE on SMN deficiency-induced neurotoxicity and muscle atrophy were examined by using SMN-deficient NSC34 motor neuron-like cells and SMA-like mice, respectively.

METHODS

Inducible SMN-knockdown NSC34 motor neuron-like cells were used to mimic SMN-deficient condition. Doxycycline (1 µg/ml) was used to induce SMN deficiency in stable NSC34 cell line carrying SMN-specific shRNA. SMAΔ7 mice were used as a severe type of SMA mouse model. Cell viability was measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) and lactate dehydrogenase (LDH) assays. Apoptotic cells and neurite length were observed by inverted microscope. Protein expressions were examined by western blots. Muscle strength of animals was evaluated by hind-limb suspension test.

RESULTS

LWDH-WE significantly increased SMN protein level, mitochondrial membrane potential and cell viability of SMN-deficient NSC34 cells. LWDH-WE attenuated SMN deficiency-induced down-regulation of B-cell lymphoma-2 (Bcl-2) and up-regulation of cytosolic cytochrome c and cleaved caspase-3. Moreover, LWDH-WE prevented SMN deficiency-induced inhibition of neurite outgrowth and activation of Ras homolog gene family, member A (RhoA)/ Rho-associated protein kinase (ROCK2)/ phospho-LIM kinase (p-LIMK)/ phospho-cofilin (p-cofilin) pathway. Furthermore, in SMA-like mice, LWDH-WE improved muscle strength and body weight accompanied with up-regulation of SMN protein in spinal cord, brain, and gastrocnemius muscle tissues.

CONCLUSION

The present study demonstrated that LWDH-WE protects motor neurons against SMN deficiency-induced neurodegeneration, and it also improves the muscle strength of SMA-like mice, suggesting the potential benefits of LWDH-WE as a complementary prescription for SMN deficiency-related diseases.

Blocking Smad2 signalling with loganin attenuates SW10 cell cycle arrest induced by TNF-α

The activity of Schwann cells (SWCs) is very important in trauma-induced nerve repair, and tumour necrosis factor-α (TNF-α) produced during tissue injury inhibits the viability of SWCs, which delays the repair of peripheral nerves. Loganin is an iridoid glycoside that has been shown to alleviate a variety of cytotoxic effects. In the current study, we evaluated the potential efficacy and the mechanism of action of loganin in TNF-α-induced cytotoxicity in SW10 cells. The experimental results indicated that loganin blocked TNF-α-mediated Smad2 activation, downregulated the expression of the G1 phase cell cycle inhibitor p15IN4KB, and upregulated the expression of the G1 phase cell cycle activator cyclin D1-CDK4/6, which upregulated E2F-1-dependent survivin expression and relieved TNF-α-induced apoptosis in SW10 cells. The protective effect of loganin on SWCs has potential medicinal value in the promotion of peripheral nerve repair and is significant for studies in the field of tissue regeneration.