Sonic hedgehog promotes neurite outgrowth of cortical neurons under oxidative stress: Involving of mitochondria and energy metabolism

Reactive Oxygen Species Induced Upregulation of TRPV1 in Dorsal Root Ganglia Results in Low Back Pain in Rats

Background

Dorsal root ganglia (DRGs) contain sensory neurons that innervate intervertebral discs (IVDs) and may play a critical role in mediating low-back pain (LBP), but the potential pathophysiological mechanism needs to be clarified.

Methods

A discogenic LBP model in rats was established by penetration of a lumbar IVD. The severity of LBP was evaluated through behavioral analysis, and the gene and protein expression levels of pro-algesic peptide substance P (SP) and calcitonin gene-related peptide (CGRP) in DRGs were quantified. The level of reactive oxygen species (ROS) in bilateral lumbar DRGs was also quantified using dihydroethidium staining. Subsequently, hydrogen peroxide solution or N-acetyl-L-cysteine was injected into DRGs to evaluate the change in LBP, and gene and protein expression levels of transient receptor potential vanilloid-1 (TRPV1) in DRGs were analyzed. Finally, an inhibitor or activator of TRPV1 was injected into DRGs to observe the change in LBP.

Results

The rats had remarkable LBP after disc puncture, manifesting as mechanical and cold allodynia and increased expression of the pro-algesic peptides SP and CGRP in DRGs. Furthermore, there was significant overexpression of ROS in bilateral lumbar DRGs, while manipulation of the level of ROS in DRGs attenuated or aggravated LBP in rats. In addition, excessive ROS in DRGs stimulated upregulation of TRPV1 in DRGs. Finally, activation or inhibition of TRPV1 in DRGs resulted in a significant increase or decrease of discogenic LBP, respectively, suggesting that ROS-induced TRPV1 has a strong correlation with discogenic LBP.

Conclusion

Increased ROS in DRGs play a primary pathological role in puncture-induced discogenic LBP, and excessive ROS-induced upregulation of TRPV1 in DRGs may be the underlying pathophysiological mechanism to cause nerve sensitization and discogenic LBP. Therapeutic targeting of ROS or TRPV1 in DRGs may provide a promising method for the treatment of discogenic LBP.

Taurine promotes axonal sprouting via Shh-mediated mitochondrial improvement in stroke

PURPOSE

Motor function is restored by axonal sprouting in ischemic stroke. Mitochondria play a crucial role in axonal sprouting. Taurine (TAU) is known to protect the brain against experimental stroke, but its role in axonal sprouting and the underlying mechanism are unclear.

METHODS

We evaluated the motor function of stroke mice using the rotarod test on days 7, 14, and 28. Immunocytochemistry with biotinylated dextran amine was used to detect axonal sprouting. We observed neurite outgrowth and cell apoptosis in cortical neurons under oxygen and glucose deprivation (OGD), respectively. Furthermore, we evaluated the mitochondrial function, adenosine triphosphate (ATP), mitochondrial DNA (mtDNA), peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PCG-1α), transcription factor A of mitochondria (TFAM), protein patched homolog 1 (PTCH1), and cellular myelocytomatosis oncogene (c-Myc).

RESULTS

TAU recovered the motor function and promoted axonal sprouting in ischemic mice. TAU restored the neuritogenesis ability of cortical neurons and reduced OGD-induced cell apoptosis. TAU also reduced reactive oxygen species, stabilized mitochondrial membrane potential, enhanced ATP and mtDNA content, increased the levels of PGC-1α, and TFAM, and restored the impaired levels of PTCH1, and c-Myc. Furthermore, these TAU-related effects could be blocked using an Shh inhibitor (cyclopamine).

CONCLUSION

Taurine promoted axonal sprouting via Shh-mediated mitochondrial improvement in ischemic stroke.

Gli1 depletion induces oxidative stress and apoptosis of nucleus pulposus cells via Fos in intervertebral disc degeneration

Background

Intervertebral disc degeneration (IDD) is the most common chronic disease. Oxidative stress and apoptosis of nucleus pulposus (NP) cells disrupt intervertebral disc (IVD) homeostasis, which is the main cause of IDD. Glioma-associated oncogene 1 (Gli1) is an important transcription factor in the Hedgehog (Hh) pathway. Depletion of Gli1 accelerates the occurrence and development of degenerative diseases. This study aimed to explore the role of aging related Gli1 depletion in the progression of IDD.

Methods

The relationship between aging related Gli1 depletion and IDD was studied in the NP tissues of human and rats of different ages, and the levels of oxidative stress and NP cell apoptosis during IDD were explored. Gli1 depletion of NP cells were established by targeting inhibitor GANT61 or lentivirus-coated Gli1 sh-RNA (sh-Gli1) to explore the role of Gli1 in NP cells and underlying mechanism. Exogenous Gli1 depletion induced IDD of rats was established by intraperitoneal injection of GANT61. Also, the roles of Fos in the Gli1 depletion induced NP cell oxidative stress, apoptosis and IDD were investigated.

Results

Gli1 was down-regulated in the tissues of degenerative NP, and the level of Gli1 was negatively correlated with the severity of aging related IDD in human and rats. Furthermore, we found enhanced oxidative stress and apoptosis in degenerative NP tissues. Gli1 depletion promoted oxidative stress and apoptosis of NP cells and resulted in the degradation of extracellular matrix (ECM) and decreased ECM synthesis. Transcriptome sequencing showed that Gli1 depletion caused Fos activation in NP cells. the effect of Gli1 depletion on the oxidative stress and apoptosis of NP cells were retarded by Fos inhibitor. In vivo, Fos inhibition alleviated the IDD induced by exogenous Gli1 depletion.

Conclusions

This study revealed for the first time that Gli1 is gradually depleted in NP with IDD progression. Exogenous Gli1 depletion causes oxidative stress and apoptosis of NP cells both in vivo and in vitro. Fos suppression effectively retards the destructive effects of Gli1 depletion on IVD homoeostasis.The translational potential of this article: This study may provide new potential targets for preventing and reversing IDD. Maintaining Gli1 expression in NP and suppressing Fos activation may be an effective treatment strategy for IDD.

An early Shh-H2O2 reciprocal regulatory interaction controls the regenerative program during zebrafish fin regeneration

Reactive oxygen species (ROS), originally classified as toxic molecules, have attracted increasing interest given their actions in cell signaling. Hydrogen peroxide (H2O2), the major ROS produced by cells, acts as a second messenger to modify redox-sensitive proteins or lipids. After caudal fin amputation, tight spatiotemporal regulation of ROS is required first for wound healing and later to initiate the regenerative program. However, the mechanisms carrying out this sustained ROS production and their integration with signaling pathways are still poorly understood. We focused on the early dialog between H2O2 and Sonic Hedgehog (Shh) during fin regeneration. We demonstrate that H2O2 controls Shh expression and that Shh in turn regulates the H2O2 level via a canonical pathway. Moreover, the means of this tight reciprocal control change during the successive phases of the regenerative program. Dysregulation of the Hedgehog pathway has been implicated in several developmental syndromes, diabetes and cancer. These data support the existence of an early positive crosstalk between Shh and H2O2 that might be more generally involved in various processes paving the way to improve regenerative processes, particularly in vertebrates.

Mitochondrial Protection and Against Glutamate Neurotoxicity via Shh/Ptch1 Signaling Pathway to Ameliorate Cognitive Dysfunction by Kaixin San in Multi-Infarct Dementia Rats

Multi-infarct dementia (MID), a prominent subtype of vascular dementia (VD), is responsible for at least 15 to 20 percent of dementia in the elderly. Mitochondrial dysfunctions and glutamate neurotoxicity due to chronic hypoperfusion and oxidative stress were regarded as the major risk factors in the pathogenesis. Kaixin San (KXS), a classic prescription of Beiji Qianjin Yaofang, was applied to treatment for "amnesia" and has been demonstrated to alleviate the cognitive deficit in a variety of dementias, including MID. However, little is known whether mitochondria and glutamate are associated with the protection of KXS in MID treatment. The aim of this study was to investigate the role of KXS in improving the cognitive function of MID rats through strengthening mitochondrial functions and antagonizing glutamate neurotoxicity via the Shh/Ptch1 signaling pathway. Our data showed that KXS significantly ameliorated memory impairment and hippocampal neuron damage in MID rats. Moreover, KXS improved hippocampal mitochondrial functions by reducing the degree of mitochondrial swelling, increasing the mitochondrial membrane potential (MMP), and elevating the energy charge (EC) and ATP content in MID rats. As expected, the concentration of glutamate and the expression of p-NMDAR1 were significantly reduced by KXS in the brain tissue of MID rats. Furthermore, our results showed that KXS noticeably activated the Shh/Ptch1 signaling pathway which was demonstrated by remarkable elevations of Ptch1, Smo, and Gli1 protein levels in the brain tissue of MID rats. Intriguingly, the inhibition of the Shh signaling pathway with cyclopamine significantly inhibited the protective effects of KXS on glutamate-induced neurotoxicity in PC12 cells. To sum up, these findings suggested that KXS protected MID rats from memory loss by rescuing mitochondrial functions as well as against glutamate neurotoxicity through activating Shh/Ptch1 signaling pathway.

Astrocytic Sonic Hedgehog Alleviates Intracerebral Hemorrhagic Brain Injury via Modulation of Blood-Brain Barrier Integrity

Background: Intracerebral hemorrhage (ICH) is a fatal subtype of stroke that lacks effective therapy. Blood-brain barrier (BBB) damage is a hallmark of ICH-induced brain injury that leads to edema formation, leukocytes infiltration, influx of blood components into the perihematomal (PHE) region, and eventually brain injury. Astrocytes are essential for the formation and maintenance of the BBB by providing secreted molecules that contribute to the association between these cells. Sonic hedgehog (SHH) derived from astrocytes promotes the maturity and integrity of the BBB by upregulating tight junctions (TJs) in brain capillary endothelial cells (ECs). However, the effect of SHH on BBB in ICH has not been investigated.

Methods: Cyclopamine (CYC) is a potent, selective inhibitor that specifically blocks the SHH signaling pathway. Here, we used pharmacological inhibitions (CYC and its derivatives) to determine a critical role of the SHH signaling pathway in promoting BBB integrity after ICH by mechanisms of regulating the TJ proteins in vivo and in vitro.

Results: The expression of astrocytic SHH was upregulated in mouse brains after ICH. Compared with the vehicle-treated group, inhibition of the SHH signaling pathway with CYC and its derivatives treatments aggravated neurological function deficits, brain edema, hematoma volume, and BBB impairment by downregulating TJs in ECs through the SHH-Gli-1 axis in vivo and in vitro.

Conclusions: SHH signaling pathway at the level of the BBB provides a barrier-promoting effect, suggesting that the SHH signaling pathway may function as a potential therapeutic target for restoring BBB function in ICH.

Dl-3-n-butylphthalide promotes neurite outgrowth of primary cortical neurons by Sonic Hedgehog signaling via upregulating Gap43

Neurite outgrowth is the basis for wiring during the development of the nervous system. Dl-3-n-butylphthalide (NBP) has been recognized as a promising treatment to improve behavioral, neurological and cognitive outcomes in ischemic stroke. However, little is known about the effect and mechanism of NBP on the neurite outgrowth. In this study, we used different methods to investigate the potential effects of NBP on the neurite extension and plasticity of immature and mature primary cortical neurons and explored the underlying mechanisms. Our results demonstrated that in immature and mature cortical neurons, NBP promoted the neurite length and intersections, increased neuritic arborization, elevated numbers of neurite branch and terminal points and improved neurite complexity and plasticity of neuronal development processes. Besides, our data revealed that NBP promoted neurite extension and branching partly by activating Shh signaling pathway via increasing Gap43 expression both in immature and mature primary cortical neurons. The present study provided new insights into the contribution of NBP in neuronal plasticity and unveiled a novel pathway to induce Gap43 expression in primary cortical neurons.

Geniposide Alleviates Oxidative Stress of Mice With Depression-Like Behaviors by Upregulating Six3os1

Depression is a major cause of disease burden and severely impairs well-being of patients around the globe. Geniposide (GP) has been revealed to play a significant role in depression treatment. Of note, RNA sequencing of this study identified highly expressed long non-coding RNA Six3os1 in response to GP treatment. Thus, we aim to explore how GP affected chronic unpredictable mild stress (CUMS)-induced depression-like behaviors in mice in vivo and in vitro and the downstream molecular mechanism related to Six3os1. The relationship of Six3os1, miR-511-3p and Fezf1 was evaluated by dual-luciferase reporter gene assay, RIP assay, and RNA pulling down assay. Ectopic expression and knockdown experiments were developed in CUMS-induced mice and neurons with or without GP treatment. In vitro experiments and behavioral tests were conducted to examine alteration of CUMS-triggered oxidative stress following different interferences. The experimental data validated that GP treatment resulted in high expression of Six3os1 and Fezf1 and poor expression of miR-511-3p in CUMS-induced neurons. Six3os1 activated the AKT signaling pathway by upregulating miR-511-3p-targeted Fezf1. Either GP treatment or overexpression of Six3os1 or Fezf1 alleviated depression-like behaviors of CUMS-induced mice. GP treatment, miR-511-3p inhibition or overexpression of Six3os1 or Fezf1 not only reduced oxidative stress in CUMS-induced mice and neurons, but also reduced CUMS-induced neuronal apoptosis. Collectively, GP treatment-mediated Six3os1 upregulation ameliorated oxidative stress of mice with depression-like behaviors via the miR-511-3p/Fezf1/AKT axis.

NRF2 and Primary Cilia: An Emerging Partnership

When not dividing, many cell types target their centrosome to the plasma membrane, where it nucleates assembly of a primary cilium, an antenna-like signaling structure consisting of nine concentric microtubule pairs surrounded by membrane. Primary cilia play important pathophysiological roles in many tissues, their dysfunction being associated with cancer and ciliopathies, a diverse group of congenital human diseases. Several recent studies have unveiled functional connections between primary cilia and NRF2 (nuclear factor erythroid 2-related factor 2), the master transcription factor orchestrating cytoprotective responses to oxidative and other cellular stresses. These NRF2-cilia relationships are reciprocal: primary cilia, by promoting autophagy, downregulate NRF2 activity. In turn, NRF2 transcriptionally regulates genes involved in ciliogenesis and Hedgehog (Hh) signaling, a cilia-dependent pathway with major roles in embryogenesis, stem cell function and tumorigenesis. Nevertheless, while we found that NRF2 stimulates ciliogenesis and Hh signaling, a more recent study reported that NRF2 negatively affects these processes. Herein, we review the available evidence linking NRF2 to primary cilia, suggest possible explanations to reconcile seemingly contradictory data, and discuss what the emerging interplay between primary cilia and NRF2 may mean for human health and disease.

A Novel Cerebroprotein Hydrolysate, CH1, Ameliorates Chronic Focal Cerebral Ischemia Injury by Promoting White Matter Integrity via the Shh/Ptch-1/Gli-1 Signaling Pathway

PURPOSE

Strokes are devastating as there are no current therapies to prevent long-term neurological deficits. Previous studies reported that cerebroprotein hydrolysate (CH) plays a role in neuronal protection in acute phase after ischemic stroke, while the long-term effects of CH upon brain plasticity and neurological outcomes after stroke are still uncertain. To address these gaps, we assessed the effect of a new cerebroprotein hydrolysate, CH1, on long-term gray and white matter integrity as well as axonal plasticity in the late phase after ischemic stroke and the potential mechanisms.

METHODS

Adult male mice were subjected to permanent distal middle cerebral artery occlusion (dMCAO), followed by daily intraperitoneal injection of CH1 for 14 days. Motor function was measured weekly through behavioral neurological evaluations. Gray matter intensity and white matter intensity were examined by immunofluorescence staining. The sonic hedgehog (Shh) inhibitor cyclopamine (CYC) was injected to determine the involvement of the Shh pathway in the therapeutic effects of CH1.

RESULTS

We found that intraperitoneal delivery of CH1, compared to vehicle administration, significantly improved long-term neurological outcomes at various times and promoted neuronal viability at 14 days but not at 28 days after stroke. Importantly, CH1 mitigated stroke-induced white matter injury and facilitated axonal plasticity in the late stage after stroke.

CONCLUSION

These results unveil a previously unappreciated role for CH in the repair of white matter and brain plasticity after stroke.

The Hedgehog Signaling Pathway in Ischemic Tissues

Hedgehog (Hh) proteins are prototypical morphogens known to regulate epithelial/mesenchymal interactions during embryonic development. In addition to its pivotal role in embryogenesis, the Hh signaling pathway may be recapitulated in post-natal life in a number of physiological and pathological conditions, including ischemia. This review highlights the involvement of Hh signaling in ischemic tissue regeneration and angiogenesis, with particular attention to the heart, the brain, and the skeletal muscle. Updated information on the potential role of the Hh pathway as a therapeutic target in the ischemic condition is also presented.

NRF2-dependent gene expression promotes ciliogenesis and Hedgehog signaling

The transcription factor NRF2 is a master regulator of cellular antioxidant and detoxification responses, but it also regulates other processes such as autophagy and pluripotency. In human embryonic stem cells (hESCs), NRF2 antagonizes neuroectoderm differentiation, which only occurs after NRF2 is repressed via a Primary Cilia-Autophagy-NRF2 (PAN) axis. However, the functional connections between NRF2 and primary cilia, microtubule-based plasma membrane protrusions that function as cellular antennae, remain poorly understood. For instance, nothing is known about whether NRF2 affects cilia, or whether cilia regulation of NRF2 extends beyond hESCs. Here, we show that NRF2 and primary cilia reciprocally regulate each other. First, we demonstrate that fibroblasts lacking primary cilia have higher NRF2 activity, which is rescued by autophagy-activating mTOR inhibitors, indicating that the PAN axis also operates in differentiated cells. Furthermore, NRF2 controls cilia formation and function. NRF2-null cells grow fewer and shorter cilia and display impaired Hedgehog signaling, a cilia-dependent pathway. These defects are not due to increased oxidative stress or ciliophagy, but rather to NRF2 promoting expression of multiple ciliogenic and Hedgehog pathway genes. Among these, we focused on GLI2 and GLI3, the transcription factors controlling Hh pathway output. Both their mRNA and protein levels are reduced in NRF2-null cells, consistent with their gene promoters containing consensus ARE sequences predicted to bind NRF2. Moreover, GLI2 and GLI3 fail to accumulate at the ciliary tip of NRF2-null cells upon Hh pathway activation. Given the importance of NRF2 and ciliary signaling in human disease, our data may have important biomedical implications.

Role of liraglutide in brain repair promotion through Sirt1-mediated mitochondrial improvement in stroke

Brain repair, especially axonal sprouting, is critical to restore motor function in disabled stroke patients. Liraglutide (LG) is a new kind of long-acting analogue of glucagon-like peptide-1 (GLP-1) and has potential protective effects in stroke. The mitochondria participate in brain repair after cerebral injury. However, the mechanism of the effect of LG on brain repair and its potential influence on mitochondria in stroke remains obscure. Here, in focal cerebral cortical ischemic mice model, LG improved the motor functional recovery and promoted axonal sprouting by restoring the activities of isocitrate dehydrogenase, α-ketoglutarate dehydrogenase, and succinate dehydrogenase. Moreover, LG remarkably increased the cell survival rate and revived the NeuN and GAP-43 levels in cortical neurons under hydrogen peroxide (H₂ O₂ ) exposure. It was also observed that LG reduced the generation of reactive oxygen species, stabilized the mitochondrial membrane potential, enhanced the levels of adenosine triphosphate, enhanced activities of mitochondrial complex-I, and decreased protein expression levels of fission-1 in H₂ O₂ -injured cortical neurons. Additionally, LG suppressed the expressions of sirtuin 1 (Sirt1) in cortical neurons exposed to H₂ O₂ . Furthermore, knockdown of Sirt1 by short interfering RNA facilitated the LG-mediated mitochondrial protection in cortical neurons under H₂ O₂ . Collectively, this data from the present study illustrated that LG exerted a promoting influence on brain repair, after cerebral ischemic injury, through Sirt1-mediated mitochondrial improvement.

Astragaloside IV and ferulic acid synergistically promote neurite outgrowth through Nrf2 activation

Recently, nuclear factor (erythroid-derived 2)-like 2 (Nrf2) have nuclear localization and nuclear exclusion signals and shuttle between the cytoplasm and the nucleus. Thus, we hypothesised that astragaloside IV (AS-IV) induction nuclear import of Nrf2 and ferulic acid (FA) inhibition nuclear export of Nrf2 contribute to synergistic antioxidant effects of combination of FA and AS-IV (FA/AS-IV). Here, we have demonstrated that FA/AS-IV enhances neurite outgrowth of PC12 cells challenged with lead acetate (PbAc) via antioxidant properties in a synergistic manner. Concomitantly, FA/AS-IV significantly promotes Nrf2 activation and induces "phase-II'' enzymes during PbAc toxicity, compared with either FA or AS-IV alone. Interestingly, FA but not AS-IV activates the extracellular signal-regulated kinases 1 and 2 (ERK1/2), leading to an increase in both de novo synthesis of Nrf2 and nuclear import of Nrf2. Simultaneously, AS-IV but not FA suppresses Fyn phosphorylation via Akt-mediated inhibition of GSK-3β, which inhibited nuclear export of Nrf2. Importantly, dual activation of both ERK1/2 and Akt by FA/AS-IV in PC12 cells challenged with PbAc is mediated by independent mechanisms, which are supported by pharmacological inhibitors. Collectively, these results support the notion that the FA/AS-IV may be promising in therapy for lead developmental neurotoxicity. This combination deserves further study in vivo.

A mitochondria-targeted organic arsenical accelerates mitochondrial metabolic disorder and function injury

Considering the vital role of mitochondria in the anti-cancer mechanism of organic arsenical, the mitochondria-targeted precursor PDT-PAO-TPP was designed and synthesized. PDT-PAO-TPP, as a delocalization lipophilic cation (DLCs) which mainly accumulated in mitochondria, contributed to improve anti-cancer efficacy and selectivity towards NB4 cells. In detail, PDT-PAO-TPP inhibited the activity of PDHC resulting in the suppression of ATP synthesis and thermogenesis disorder. Additionally, the inhibition of respiratory chain complex I and IV by short-time incubation of PDT-PAO-TPP also accelerated the respiration dysfunction and continuous generation of ROS. These results led to the release of cytochrome c and activation of caspase family-dependent apoptosis. Different from the mechanism of PDT-PAO in HL-60 cells, it mainly induced the mitochondrial metabolic disturbance resulting in the intrinsic apoptosis via inhibiting the activity of PDHC in NB4 cells, which also implied that the efficacy exertion of organic arsenical was a complex process involved in many aspects of cellular function. This study systematically clarifies the anti-cancer mechanism of mitochondria-targeted organic arsenical PDT-PAO-TPP and confirms the new target PDHC of organic arsenicals, which further supports the organic arsenical as a promising anticancer drug.

Antidepressant, anti-inflammatory, and antioxidant effects of electroacupuncture through sonic hedgehog-signaling pathway in a rat model of poststroke depression

Background: Poststroke depression (PSD) is the most frequent psychological sequela after stroke. Electroacupuncture (EA) treatment is effective for PSD. The study aimed at clarifying the mechanisms of EA's antidepressant effects in a PSD rat model. Methods: We used middle cerebral artery occlusion to establish the rat model of PSD. Tests of sucrose preference and locomotor activity were performed to examine depressive-like behaviors. We measured malondialdehyde, GSH, SOD, IL6, IL1β, TNFα, and 5HT with ELISA. The hippocampal Shh-signaling pathway was assessed by Western blot. Results: EA significantly decreased sucrose preference and locomotor activities of PSD rats, reduced IL6, TNFα, increased GSH, and upregulated 5HT, and also slightly reduced IL1β and malondialdehyde, all of which were measured with ELISA. The Shh-signaling pathway assessed by Western blotting was activated by EA. Those changes were inhibited by the Shh-pathway inhibitor cyclopamine. Conclusion: EA effectively alleviated depressive-like behaviors in PSD by suppressing inflammation and oxidative stress through activation of the Shh-signaling pathway.

GM604 regulates developmental neurogenesis pathways and the expression of genes associated with amyotrophic lateral sclerosis

Background

Amyotrophic lateral sclerosis (ALS) is currently an incurable disease without highly effective pharmacological treatments. The peptide drug GM604 (GM6 or Alirinetide) was developed as a candidate ALS therapy, which has demonstrated safety and good drug-like properties with a favorable pharmacokinetic profile. GM6 is hypothesized to bolster neuron survival through the multi-target regulation of developmental pathways, but mechanisms of action are not fully understood.

Methods

This study used RNA-seq to evaluate transcriptome responses in SH-SY5Y neuroblastoma cells following GM6 treatment (6, 24 and 48 h).

Results

We identified 2867 protein-coding genes with expression significantly altered by GM6 (FDR < 0.10). Early (6 h) responses included up-regulation of Notch and hedgehog signaling components, with increased expression of developmental genes mediating neurogenesis and axon growth. Prolonged GM6 treatment (24 and 48 h) altered the expression of genes contributing to cell adhesion and the extracellular matrix. GM6 further down-regulated the expression of genes associated with mitochondria, inflammatory responses, mRNA processing and chromatin organization. GM6-increased genes were located near GC-rich motifs interacting with C2H2 zinc finger transcription factors, whereas GM6-decreased genes were located near AT-rich motifs associated with helix-turn-helix homeodomain factors. Such motifs interacted with a diverse network of transcription factors encoded by GM6-regulated genes (STAT3, HOXD11, HES7, GLI1). We identified 77 ALS-associated genes with expression significantly altered by GM6 treatment (FDR < 0.10), which were known to function in neurogenesis, axon guidance and the intrinsic apoptosis pathway.

Conclusions

Our findings support the hypothesis that GM6 acts through developmental-stage pathways to influence neuron survival. Gene expression responses were consistent with neurotrophic effects, ECM modulation, and activation of the Notch and hedgehog neurodevelopmental pathways. This multifaceted mechanism of action is unique among existing ALS drug candidates and may be applicable to multiple neurodegenerative diseases.

Electronic supplementary material

The online version of this article (10.1186/s40035-018-0135-7) contains supplementary material, which is available to authorized users.

Emerging Roles of Sonic Hedgehog in Adult Neurological Diseases: Neurogenesis and Beyond

Sonic hedgehog (Shh), a member of the hedgehog (Hh) family, was originally recognized as a morphogen possessing critical characters for neural development during embryogenesis. Recently, however, Shh has emerged as an important modulator in adult neural tissues through different mechanisms such as neurogenesis, anti-oxidation, anti-inflammation, and autophagy. Therefore, Shh may potentially have clinical application in neurodegenerative diseases and brain injuries. In this article, we present some examples, including ours, to show different aspects of Shh signaling and how Shh agonists or mimetics are used to alter the neuronal fates in various disease models, both in vitro and in vivo. Other potential mechanisms that are discussed include alteration of mitochondrial function and anti-aging effect; both are critical for age-related neurodegenerative diseases. A thorough understanding of the protective mechanisms elicited by Shh may provide a rationale to design innovative therapeutic regimens for various neurodegenerative diseases.

Rosuvastatin Improves Neurite Outgrowth of Cortical Neurons against Oxygen-Glucose Deprivation via Notch1-mediated Mitochondrial Biogenesis and Functional Improvement

Neurogenesis, especially neurite outgrowth is an essential element of neuroplasticity after cerebral ischemic injury. Mitochondria may supply ATP to power fundamental developmental processes including neuroplasticity. Although rosuvastatin (RSV) displays a potential protective effect against cerebral ischemia, it remains unknown whether it modulates mitochondrial biogenesis and function during neurite outgrowth. Here, the oxygen-glucose deprivation (OGD) model was used to induce ischemic injury. We demonstrate that RSV treatment significantly increases neurite outgrowth in cortical neurons after OGD-induced damage. Moreover, we show that RSV reduces the generation of reactive oxygen species (ROS), protects mitochondrial function, and elevates the ATP levels in cortical neurons injured by OGD. In addition, we found that, under these conditions, RSV treatment increases the mitochondrial DNA (mtDNA) content and the mRNA levels of mitochondrial transcription factor A (TFAM) and nuclear respiratory factor 1 (NRF-1). Furthermore, blocking Notch1, which is expressed in primary cortical neurons, reverses the RSV-dependent induction of mitochondrial biogenesis and function under OGD conditions. Collectively, these results suggest that RSV could restore neurite outgrowth in cortical neurons damaged by OGD in vitro, by preserving mitochondrial function and improving mitochondrial biogenesis, possibly through the Notch1 pathway.

Baihui (DU20)-penetrating-Qubin (GB7) acupuncture inhibits apoptosis in the perihemorrhagic penumbra

Baihui (DU20)-penetrating-Qubin (GB7) acupuncture can inhibit inflammatory reactions and activate signaling pathways related to proliferation after intracerebral hemorrhage. However, there is no research showing the relationship between this treatment and cell apoptosis. Rat models of intracerebral hemorrhage were established by injecting 60 μL of autologous blood into the right side of the caudate-putamen. Six hours later, the needle traveled subcutaneously from the Baihui acupoint to Qubin acupoint. The needle was alternately rotated (180 ± 10 turns/min) manually along clockwise and counter-clockwise directions. Stimulation lasted for 7 days, and was performed three times each for 6 minutes with 6-minute intervals between stimulations. Rats intraperitoneally receiving Sonic hedgehog pathway activator, purmorphamine (1 mg/kg per day), served as positive controls. Motor and sensory function were assessed using the Ludmila Belayev test. Extent of pathological changes were measured in the perihemorrhagic penumbra using hematoxylin-eosin staining. Apoptosis was examined by terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick end labeling assay. Expression of smoothened (Smo) and glioma-associated homolog 1 (Gli1) was determined by western blot assay. Our results showed that Baihui-penetrating-Qubin acupuncture promoted recovery of motor and sensory function, reduced the apoptotic cell percentage in the perihemorrhagic penumbra, and up-regulated Smo and Gli1 expression. We conclude that Baihui-penetrating-Qubin acupuncture can mitigate hemorrhage and promote functional recovery of the brain in a rat model of intracerebral hemorrhage, possibly by activating the Sonic hedgehog pathway.