cAMP Response Element-Binding Protein (CREB): A Possible Signaling Molecule Link in the Pathophysiology of Schizophrenia

Common Molecular Signatures Between Coronavirus Infection and Alzheimer's Disease Reveal Targets for Drug Development

BACKGROUND

Cognitive decline is a common consequence of COVID-19, and studies suggest a link between COVID-19 and Alzheimer's disease (AD). However, the molecular mechanisms underlying this association remain unclear.

OBJECTIVE

To understand the potential molecular mechanisms underlying the association between COVID-19 and AD development, and identify the potential genetic targets for pharmaceutical approaches to reduce the risk or delay the development of COVID-19-related neurological pathologies.

METHODS

We analyzed transcriptome datasets of 638 brain samples using a novel Robust Rank Aggregation method, followed by functional enrichment, protein-protein, hub genes, gene-miRNA, and gene-transcription factor (TF) interaction analyses to identify molecular markers altered in AD and COVID-19 infected brains.

RESULTS

Our analyses of frontal cortex from COVID-19 and AD patients identified commonly altered genes, miRNAs and TFs. Functional enrichment and hub gene analysis of these molecular changes revealed commonly altered pathways, including downregulation of the cyclic adenosine monophosphate (cAMP) signaling and taurine and hypotaurine metabolism, alongside upregulation of neuroinflammatory pathways. Furthermore, gene-miRNA and gene-TF network analyses provided potential up- and downstream regulators of identified pathways.

CONCLUSION

We found that downregulation of cAMP signaling pathway, taurine metabolisms, and upregulation of neuroinflammatory related pathways are commonly altered in AD and COVID-19 pathogenesis, and may make COVID-19 patients more susceptible to cognitive decline and AD. We also identified genetic targets, regulating these pathways that can be targeted pharmaceutically to reduce the risk or delay the development of COVID-19-related neurological pathologies and AD.

BDNF/TrkB signaling endosomes in axons coordinate CREB/mTOR activation and protein synthesis in the cell body to induce dendritic growth in cortical neurons

Brain-derived neurotrophic factor (BDNF) and its receptors tropomyosin kinase receptor B (TrkB) and the p75 neurotrophin receptor (p75) are the primary regulators of dendritic growth in the CNS. After being bound by BDNF, TrkB and p75 are endocytosed into endosomes and continue signaling within the cell soma, dendrites, and axons. We studied the functional role of BDNF axonal signaling in cortical neurons derived from different transgenic mice using compartmentalized cultures in microfluidic devices. We found that axonal BDNF increased dendritic growth from the neuronal cell body in a cAMP response element-binding protein (CREB)-dependent manner. These effects were dependent on axonal TrkB but not p75 activity. Dynein-dependent BDNF-TrkB-containing endosome transport was required for long-distance induction of dendritic growth. Axonal signaling endosomes increased CREB and mTOR kinase activity in the cell body, and this increase in the activity of both proteins was required for general protein translation and the expression of Arc, a plasticity-associated gene, indicating a role for BDNF-TrkB axonal signaling endosomes in coordinating the transcription and translation of genes whose products contribute to learning and memory regulation.

Dikkopf-1 promotes matrix mineralization of osteoblasts by regulating Ca+-CAMK2A- CREB1 pathway

Dickkopf-1 (DKK1) is a secreted protein that acts as an antagonist of the canonical WNT/β-catenin pathway, which regulates osteoblast differentiation. However, the role of DKK1 on osteoblast differentiation has not yet been fully clarified. Here, we investigate the functional role of DKK1 on osteoblast differentiation. Primary osteoprogenitor cells were isolated from human spinal bone tissues. To examine the role of DKK1 in osteoblast differentiation, we manipulated the expression of DKK1, and the cells were differentiated into mature osteoblasts. DKK1 overexpression in osteoprogenitor cells promoted matrix mineralization of osteoblast differentiation but did not promote matrix maturation. DKK1 increased Ca⁺ influx and activation of the Ca⁺/calmodulin-dependent protein kinase II Alpha (CAMK2A)-cAMP response element-binding protein 1 (CREB1) and increased translocation of p-CREB1 into the nucleus. In contrast, stable DKK1 knockdown in human osteosarcoma cell line SaOS2 exhibited reduced nuclear translocation of p-CREB1 and matrix mineralization. Overall, we suggest that manipulating DKK1 regulates the matrix mineralization of osteoblasts by Ca⁺-CAMK2A-CREB1, and DKK1 is a crucial gene for bone mineralization of osteoblasts. [BMB Reports 2022; 55(12): 627-632].

Anti-Melanogenesis Effects of a Cyclic Peptide Derived from Flaxseed via Inhibition of CREB Pathway

Linosorbs (Los) are cyclic peptides from flaxseed oil composed of the LO mixture (LOMIX). The activity of LO has been reported as being anti-cancer and anti-inflammatory. However, the study of skin protection has still not proceeded. In particular, there are poorly understood mechanisms of melanogenesis to LO. Therefore, we investigated the anti-melanogenesis effects of LOMIX and LO, and its activity was examined in mouse melanoma cell lines. The treatment of LOMIX (50 and 100 μg/mL) and LO (6.25-50 μM) suppressed melanin secretion and synthesis, which were 3-fold increased, in a dose-dependent manner, up to 95%. In particular, [1-9-NαC]-linusorb B3 (LO1) and [1-9-NαC]-linusorb B2 (LO2) treatment (12.5 and 25 μM) highly suppressed the synthesis of melanin in B16F10 cell lines up to 90%, without toxicity. LOMIX and LOs decreased the 2- or 3-fold increased mRNA levels, including the microphthalmia-associated transcription factor (MITF), Tyrosinase, tyrosinase-related protein 1 (TYRP1), and tyrosinase-related protein 2 (TYRP2) at the highest concentration (25 μM). Moreover, the treatment of 25 μM LO1 and LO2 inhibited the expression of MITF and phosphorylation of upper regulatory proteins such as CREB and PKA. Taken together, these results suggested that LOMIX and its individual LO could inhibit melanin synthesis via downregulating the CREB-dependent signaling pathways, and it could be used for novel therapeutic materials in hyperpigmentation.

Antipsychotics-Induced Changes in Synaptic Architecture and Functional Connectivity: Translational Implications for Treatment Response and Resistance

Schizophrenia is a severe mental illness characterized by alterations in processes that regulate both synaptic plasticity and functional connectivity between brain regions. Antipsychotics are the cornerstone of schizophrenia pharmacological treatment and, beyond occupying dopamine D2 receptors, can affect multiple molecular targets, pre- and postsynaptic sites, as well as intracellular effectors. Multiple lines of evidence point to the involvement of antipsychotics in sculpting synaptic architecture and remodeling the neuronal functional unit. Furthermore, there is an increasing awareness that antipsychotics with different receptor profiles could yield different interregional patterns of co-activation. In the present systematic review, we explored the fundamental changes that occur under antipsychotics' administration, the molecular underpinning, and the consequences in both acute and chronic paradigms. In addition, we investigated the relationship between synaptic plasticity and functional connectivity and systematized evidence on different topographical patterns of activation induced by typical and atypical antipsychotics.

Mechanisms Underlying Cognitive Impairment Induced by Prenatal Alcohol Exposure

Alcohol is one of the most commonly used illicit substances among pregnant women. Clinical and experimental studies have revealed that prenatal alcohol exposure affects fetal brain development and ultimately results in the persistent impairment of the offspring's cognitive functions. Despite this, the rate of alcohol use among pregnant women has been progressively increasing. Various aspects of human and animal behavior, including learning and memory, are dependent on complex interactions between multiple mechanisms, such as receptor function, mitochondrial function, and protein kinase activation, which are especially vulnerable to alterations during the developmental period. Thus, the exploration of the mechanisms that are altered in response to prenatal alcohol exposure is necessary to develop an understanding of how homeostatic imbalance and various long-term neurobehavioral impairments manifest following alcohol abuse during pregnancy. There is evidence that prenatal alcohol exposure results in vast alterations in mechanisms such as long-term potentiation, mitochondrial function, and protein kinase activation in the brain of offspring. However, to the best of our knowledge, there are very few recent reviews that focus on the cognitive effects of prenatal alcohol exposure and the associated mechanisms. Therefore, in this review, we aim to provide a comprehensive summary of the recently reported alterations to various mechanisms following alcohol exposure during pregnancy, and to draw potential associations with behavioral changes in affected offspring.

Aging-suppressor Klotho: Prospects in diagnostics and therapeutics

INTRODUCTION

The protein Klotho (KL) was first discovered in KL-deficient mice, which developed a syndrome similar to premature aging in humans. Since then, KL has been implicated in multiple molecular signaling pathways and diseases. KL has been shown to have anti-aging, healthspan and lifespan extending, cognitive enhancing, anti-oxidative, anti-inflammatory, and anti-tumor properties. KL levels decrease with age and in many diseases. Therefore, it has been of great interest to develop a KL-boosting or restoring drug, or to supplement endogenous Klotho with exogenous Klotho genetic material or recombinant Klotho protein, and to use KL levels in the body as a marker for the efficacy of such drugs and as a biomarker for the diagnosis and management of diseases.

OBJECTIVE

The goal of this study was to provide a comprehensive review of KL levels across age groups in individuals who are healthy or have certain health conditions, using four sources: blood, cerebrospinal fluid, urine, and whole biopsy/necropsy tissue. By doing so, baseline KL levels can be identified across the lifespan, in the absence or presence of disease. In turn, these findings can be used to guide the development of future KL-based therapeutics and biomarkers, which will heavily rely on an individual's baseline KL range to be efficacious.

METHODS

A total of 65 studies were collected primarily using the PubMed database. Research articles that were published up to April 2022 were included. Statistical analysis was conducted using RStudio.

RESULTS

Mean and median blood KL levels in healthy individuals, mean blood KL levels in individuals with renal conditions, and mean blood KL levels in individuals with metabolic or endocrine conditions were shown to decrease with age. Similarly, CSF KL levels in patients with AD also declined compared with age-matched controls.

CONCLUSIONS

The present study confirms the trend that KL levels in blood decrease with age in humans, among those who are healthy, and even further among those with renal and endocrine/metabolic illnesses. Further, by drawing this trend from multiple published works, we were able to provide a general idea of baseline KL ranges, specifically in blood in these populations. These data add to the current knowledge on normal KL levels in the body and how they change with time and in disease, and can potentially support efforts to create KL-based treatments and screening tools to better manage aging, renal, and metabolic/endocrine diseases.

Dikkopf-1 promotes matrix mineralization of osteoblasts by regulating Ca+-CAMK2A- CREB1 pathway

Dickkopf-1 (DKK1) is a secreted protein that acts as an antagonist of the canonical WNT/β-catenin pathway, which regulates osteoblast differentiation. However, the role of DKK1 on osteoblast differentiation has not yet been fully clarified. Here, we investigate the functional role of DKK1 on osteoblast differentiation. Primary osteoprogenitor cells were isolated from human spinal bone tissues. To examine the role of DKK1 in osteoblast differentiation, we manipulated the expression of DKK1, and the cells were differentiated into mature osteoblasts. DKK1 overexpression in osteoprogenitor cells promoted matrix mineralization of osteoblast differentiation but did not promote matrix maturation. DKK1 increased Ca+ influx and activation of the Ca+/calmodulin-dependent protein kinase II Alpha (CAMK2A)-cAMP response element-binding protein 1 (CREB1) and increased translocation of p-CREB1 into the nucleus. In contrast, stable DKK1 knockdown in human osteosarcoma cell line SaOS2 exhibited reduced nuclear translocation of p-CREB1 and matrix mineralization. Overall, we suggest that manipulating DKK1 regulates the matrix mineralization of osteoblasts by Ca+-CAMK2A-CREB1, and DKK1 is a crucial gene for bone mineralization of osteoblasts. [BMB Reports 2022; 55(12): 627-632].

cGMP Signaling in the Neurovascular Unit-Implications for Retinal Ganglion Cell Survival in Glaucoma

Glaucoma is a progressive age-related disease of the visual system and the leading cause of irreversible blindness worldwide. Currently, intraocular pressure (IOP) is the only modifiable risk factor for the disease, but even as IOP is lowered, the pathology of the disease often progresses. Hence, effective clinical targets for the treatment of glaucoma remain elusive. Glaucoma shares comorbidities with a multitude of vascular diseases, and evidence in humans and animal models demonstrates an association between vascular dysfunction of the retina and glaucoma pathology. Integral to the survival of retinal ganglion cells (RGCs) is functional neurovascular coupling (NVC), providing RGCs with metabolic support in response to neuronal activity. NVC is mediated by cells of the neurovascular unit (NVU), which include vascular cells, glial cells, and neurons. Nitric oxide-cyclic guanosine monophosphate (NO-cGMP) signaling is a prime mediator of NVC between endothelial cells and neurons, but emerging evidence suggests that cGMP signaling is also important in the physiology of other cells of the NVU. NO-cGMP signaling has been implicated in glaucomatous neurodegeneration in humans and mice. In this review, we explore the role of cGMP signaling in the different cell types of the NVU and investigate the potential links between cGMP signaling, breakdown of neurovascular function, and glaucoma pathology.

Galangin inhibited ferroptosis through activation of the PI3K/AKT pathway in vitro and in vivo

Ferroptosis is an iron-dependent form of nonapoptotic cell death characterized by the accumulation of lipid peroxides in cells. In recent years, extensive attention has been dedicated to exploring safe and effective natural ferroptosis regulators which can provide novel treatment strategies for ferroptosis-related diseases. This study identified galangin, a natural flavonoid, as an effective inhibitor of ferroptosis, which could increase cell viability in RSL3-inhibited HT1080 cells, decrease levels of lipid ROS and MDA, improve PTGS2 mRNA expression, and enhance the expression of glutathione peroxidase 4 (GPX4). Ferroptosis is widely present in ischemia-reperfusion (IR) injury. This study found that galangin significantly ameliorated the pathological damage of liver tissue in mice with IR, reduced levels of serum ALT, AST, and MDA, and increased the expression of GPX4. The results of RNA-seq exhibited ferroptosis was significant and the PI3K/AKT pathway deserved to explore the inhibition effects of galangin on ferroptosis. Indeed, galangin treatment significantly rescued RSL3-inhibited phosphorylation levels of PI3K, AKT, and CREB proteins, and the ferroptosis inhibitory effects of galangin were counteracted by PI3K inhibitor LY294002. These findings indicated that galangin may exert its anti-ferroptosis effects via activating the PI3K/AKT/CREB signaling pathway and it will hopefully serve as a promising effective measure to attenuate IR injury by inhibiting ferroptosis.

Gintonin stimulates dendritic growth in striatal neurons by activating Akt and CREB

Gintonin, a glycolipid protein conjugated with lysophosphatidic acid (LPA), is a newly identified compound extracted from Korean ginseng. LPA receptor isotypes exhibit high affinity for gintonin and mediate intracellular calcium signaling in various animal cell models. In this study, we found that gintonin induced the activation of Akt and cAMP-response element binding protein (CREB) in mouse striatal neurons, and chronic treatment with gintonin potently induced dendritic growth and filopodia formation. Gintonin-induced Akt/CREB activation and dendritic development were significantly impaired by LPA receptor (LPAR1/3) inhibition with Ki16425. Intriguingly, prolonged treatment with gintonin ameliorated the reduction in dendritic formation caused by Shank3 and Slitrk5 deficiency in the striatal neurons. In addition, gintonin and brain-derived neurotrophic factor (BDNF) had a synergistic effect on AKT/CREB activation and dendritic growth at suboptimal concentrations. These findings imply that gintonin-stimulated LPA receptors play a role in dendritic growth in striatal neurons and that they may act synergistically with BDNF, which is known to play a role in dendritogenesis.

Yuk-Gunja-Tang attenuates neuronal death and memory impairment via ERK/CREB/BDNF signaling in the hippocampi of experimental Alzheimer’s disease model

Yuk-Gunja-Tang (YG) is the Korean traditional medicine in East Asia for gastrointestinal disorders. In the present study, we determined the protective effects of YG on glutamate-induced cytotoxicity in HT22 hippocampal neuronal cells and mice with scopolamine-induced memory impairment. In vitro assessments were performed using a cell viability assay, flow cytometry, and Western blotting, while in vivo assessments were performed in C57BL/6 mice administered with YG for 7 days and injected with scopolamine (1 mg/kg) for 7 days. We assessed the memory function using the Y-maze, novel object recognition, and passive avoidance tests. Protein expression analyses and histological analyses were performed using hippocampal tissues. YG treatment significantly restored cell viability against glutamate-induced apoptosis. It significantly suppressed glutamate-induced reactive oxygen species accumulation and mitochondrial dysfunction. It also increased Bcl-2 protein expression and decreased HO-1 protein expression. It activated the extracellular signal-regulated kinase/cAMP response element binding protein (ERK/CREB) signaling pathway and increased the expression of brain-derived neurotrophic factor (BDNF) under excitotoxic conditions. In the scopolamine-injected mice, YG ameliorated memory impairment in the Y-maze, novel object recognition, and passive avoidance tests; restored dysfunction in the acetylcholine, acetylcholinesterase expression levels; reduced neuronal damage in Nissl staining; and increased BDNF and phosphorylated ERK and CREB levels in Western blotting and immunofluorescence staining. Thus, YG exerted neuroprotective effects by activating ERK/CREB/BDNF signaling in the hippocampus, indicating its potential cognition-enhancing effects, especially in Alzheimer’s disease.

TPM1 mediates inflammation downstream of TREM2 via the PKA/CREB signaling pathway

Background

Microglia, the innate immune cells in the central nervous system, play an essential role in brain homeostasis, neuroinflammation and brain infections. Dysregulated microglia, on the other hand, are associated with neurodegenerative diseases, yet the mechanisms underlying pro-inflammatory gene expression in microglia are incompletely understood.

Methods

We investigated the role of the actin-associated protein tropomyosin 1 (TPM1) in regulating pro-inflammatory phenotype of microglia in the retina by using a combination of cell culture, immunocytochemistry, Western blot, qPCR, TUNEL, RNA sequencing and electroretinogram analysis. TREM2^−/− mice were used to investigate whether TPM1 regulated pro-inflammatory responses downstream of TREM2. To conditionally deplete microglia, we backcrossed CX3CR1^CreER mice with Rosa26^iDTR mice to generate CX3CR1^CreER:Rosa26^iDTR mice.

Results

We revealed a vital role for TPM1 in regulating pro-inflammatory phenotype of microglia. We found that TPM1 drove LPS-induced inflammation and neuronal death in the retina via the PKA/CREB pathway. TPM1 knockdown ameliorated LPS-induced inflammation in WT retinas yet exaggerated the inflammation in TREM2^−/− retinas. RNA sequencing revealed that genes associated with M1 microglia and A1 astrocytes were significantly downregulated in LPS-treated WT retinas but upregulated in LPS-treated TREM2^−/− retinas after TPM1 knockdown. Mechanistically, we demonstrated that CREB activated by TPM1 knockdown mediated anti-inflammatory genes in LPS-treated WT retinas but pro-inflammatory genes in LPS-treated TREM2^−/− retinas, suggesting a novel role for TREM2 as a brake on TPM1-mediated inflammation. Furthermore, we identified that TPM1 regulated inflammation downstream of TREM2 and in a microglia-dependent manner.

Conclusions

We demonstrate that TPM1 mediates inflammation downstream of TREM2 via the PKA/CREB signaling pathway. Our findings suggest that TPM1 could be a potential target for therapeutic intervention in brain diseases.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12974-022-02619-3.

Inhibition of phosphodiesterase: A novel therapeutic target for the treatment of mild cognitive impairment and Alzheimer's disease

Alzheimer's disease (AD) is the most common form of dementia and is ranked as the 6th leading cause of death in the US. The prevalence of AD and dementia is steadily increasing and expected cases in USA is 14.8 million by 2050. Neuroinflammation and gradual neurodegeneration occurs in Alzheimer's disease. However, existing medications has limitation to completely abolish, delay, or prevent disease progression. Phosphodiesterases (PDEs) are large family of enzymes to hydrolyze the 3'-phosphodiester links in cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP) in signal-transduction pathways for generation of 5'-cyclic nucleotides. It plays vital role to orchestrate several pharmacological activities for proper cell functioning and regulating the levels of cAMP and cGMP. Several evidence has suggested that abnormal cAMP signaling is linked to cognitive problems in neurodegenerative disorders like AD. Therefore, the PDE family has become a widely accepted and multipotential therapeutic target for neurodegenerative diseases. Notably, modulation of cAMP/cGMP by phytonutrients has a huge potential for the management of AD. Natural compounds have been known to inhibit phosphodiesterase by targeting key enzymes of cGMP synthesis pathway, however, the mechanism of action and their therapeutic efficacy has not been explored extensively. Currently, few PDE inhibitors such as Vinpocetine and Nicergoline have been used for treatment of central nervous system (CNS) disorders. Considering the role of flavonoids to inhibit PDE, this review discussed the therapeutic potential of natural compounds with PDE inhibitory activity for the treatment of AD and related dementia.

Hepatic cytokine-inducible SH2-containing protein (CISH) regulates gluconeogenesis via cAMP-responsive element binding protein (CREB)

Impairment of gluconeogenesis is a key factor responsible for hyperglycemia in patients with type 2 diabetes. As an important member of the suppressors of cytokine signaling (SOCS) protein family, many physiological functions of cytokine-inducible SH2-containing protein (CISH) have been described; however, the role of hepatic CISH in gluconeogenesis is poorly understood. In the present study, we observed that hepatic CISH expression was reduced in fasted wild-type (WT) mice. Overexpression of CISH decreased glucose production in mouse primary hepatocytes, while silencing of CISH had the opposite effects. In addition, adenovirus-mediated hepatic CISH overexpression resulted in improved glucose tolerance and decreased gluconeogenesis in WT and leptin receptor-deficient diabetic (db/db) mice. In contrast, adenovirus-mediated hepatic CISH knockdown impaired glucose tolerance and increased gluconeogenesis in WT mice. We also generated liver-specific CISH knockout (LV-CISH KO) mice and discovered that these mice had a similar phenotype in glucose tolerance and gluconeogenesis as mice injected with adenoviruses that knockdown CISH expression. Mechanistically, we found that CISH overexpression decreased and CISH knockdown increased the mRNA and protein levels of glucose-6-phosphatase (G6Pase) and phosphoenolpyruvate carboxykinase 1 (PEPCK), two key enzymes involved in gluconeogenesis, in vitro, and in vivo. Moreover, we discovered that the phosphorylation of cAMP-responsive element binding protein 1 (CREB), a transcription factor of G6pase and Pepck, was required for regulating gluconeogenesis by CISH. Taken together, this study identifies hepatic CISH as an important regulator of gluconeogenesis. Our results also provide important insights into the metabolic functions of the SOCS protein family and the potential targets for the treatment of diabetes.

Bioinformatics analysis reveals the potential target of rosiglitazone as an antiangiogenic agent for breast cancer therapy

Background

Several studies have demonstrated the antitumor activity of rosiglitazone (RGZ) in cancer cells, including breast cancer cells. However, the molecular targets of RGZ in the inhibition of angiogenesis in breast cancer cells remain unclear. This study aimed to explore the potential targets of RGZ in inhibiting breast cancer angiogenesis using bioinformatics-based analysis.

Results

Venn diagram analysis revealed 29 TR proteins. KEGG pathway enrichment analysis demonstrated that TR regulated the adipocytokine, AMPK, and PPAR signaling pathways. Oncoprint analysis showed genetic alterations in FABP4 (14%), ADIPOQ (2.9%), PPARG (2.8%), PPARGC1A (1.5%), CD36 (1.7%), and CREBBP (11%) in patients with breast cancer in a TCGA study. The mRNA levels of FABP4, ADIPOQ, PPARG, CD36, and PPARGC1A were significantly lower in patients with breast cancer than in those without breast cancer. Analysis of gene expression using bc-GenExMiner showed that the mRNA levels of FABP, ADIPOQ, PPARG, CD36, PPARGC1A, and CREBBP were significantly lower in basal-like and triple-negative breast cancer (TNBC) cells than in non-basal-like and non-TNBC cells. In general, the protein levels of these genes were low, except for that of CREBBP. Patients with breast cancer who had low mRNA levels of FABP4, ADIPOQ, PPARG, and PPARGC1A had lower overall survival rates than those with high mRNA levels, which was supported by the overall survival related to DNA methylation. Correlation analysis of immune cell infiltration with TR showed a correlation between TR and immune cell infiltration, highlighting the potential of RGZ for immunotherapy.

Conclusion

This study explored the potential targets of RGZ as antiangiogenic agents in breast cancer therapy and highlighted FABP4, ADIPOQ, PPARG, PPARGC1A, CD36, and CREBBP as potential targets of RGZ. These findings require further validation to explore the potential of RGZ as an antiangiogenic agent.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12863-022-01086-2.

Recent studies have focused on the development of indirect angiogenesis inhibitors.

Bioinformatics-based identification of potential rosiglitazone target genes to inhibit breast cancer angiogenesis.

FABP4, ADIPOQ, PPARG, PPARGC1A, CD36, and CREBBP are potential targets of rosiglitazone.

Forskolin, an Adenylcyclase/cAMP/CREB Signaling Activator Restoring Myelin-Associated Oligodendrocyte Destruction in Experimental Ethidium Bromide Model of Multiple Sclerosis

Multiple sclerosis (MS) is a chronic neurodegenerative disease marked by oligodendrocyte loss, which results in central neuronal demyelination. AC/cAMP/CREB signaling dysregulation is involved in the progression of MS, including mitochondrial dysfunctions, reduction in nerve growth factors, neuronal inflammation, apoptosis, and white matter degeneration. Our previous research has shown that Forskolin (FSK), a naturally occurring direct adenylyl cyclase (AC)/cAMP/CREB activator, has neuroprotective potential to alleviate pathogenic factors linked with numerous neurological abnormalities. The current study intends to explore the neuroprotective potential of FSK at doses of 40 mg/kg and 60 mg/kg alone, as well as in combination with conventional medicines, such as Fingolimod (FNG), Donepezil (DON), Memantine (MEM), and Simvastatin (SIM) in EB-induced demyelinated experimental MS rats. Adult Wistar rats were divided into nine groups, and EB was infused stereotaxically in the rat brain’s intracerebropeduncle (ICP) area. Chronic gliotoxin EB treatment results in demyelination as well as motor and cognitive dysfunctions. FSK, combined with standard medications, improves behavioral dysfunctions, such as neuromuscular and motor deficits and memory and cognitive abnormalities. Following pharmacological treatments improved remyelination by enhancing myelin basic protein and increasing AC, cAMP, and CREB levels in brain homogenates. Furthermore, FSK therapy restored brain mitochondrial-ETC complex enzymes and neurotransmitter levels while decreasing inflammatory cytokines and oxidative stress markers. The Luxol fast blue (LFB) stain results further indicate FSK’s neuroprotective potential in preventing oligodendrocyte death. Therefore, the results of these studies contribute to a better understanding of the possible role that natural phytochemicals FSK could have in preventing motor neuron diseases, such as multiple sclerosis.

Silencing of hypothalamic FGF11 prevents diet-induced obesity

Fibroblast growth factor 11 (FGF11) is a member of the intracellular fibroblast growth factor family. Here, we report the central role of FGF11 in the regulation of metabolism. Lentiviral injection of Fgf11 shRNA into the arcuate nucleus of the mouse hypothalamus decreased weight gain and fat mass, increased brown adipose tissue thermogenesis, and improved glucose and insulin intolerances under high-fat diet conditions. Fgf11 was expressed in the NPY–expressing neurons, and Fgf11 knockdown considerably decreased Npy expression and projection, leading to increased expression of tyrosine hydroxylase in the paraventricular nucleus. Mechanistically, FGF11 regulated Npy gene expression through the glycogen synthase kinase 3–cAMP response element-binding protein pathway. Our study defines the physiological significance of hypothalamic FGF11 in the regulation of metabolism in response to overnutrition such as high-fat diet.

Ameliorating effect offluoxetine on tamoxifen-induced memory loss: The role of corticolimbic NMDA receptors and CREB/BDNF/cFos signaling pathways in rats

Tamoxifen-induced cognitive dysfunction may lead to fluoxetine consumption in patients with breast cancer. Since the brain mechanisms are unclear in tamoxifen/fluoxetine therapy, the blockade effect of hippocampal/amygdala/prefrontal cortical NMDA receptors was examined in fluoxetine/tamoxifen-induced memory retrieval. We also assessed the corticolimbic signaling pathways in memory retrieval under the drug treatment in adult male Wistar rats. Using the Western blot technique, the expression levels of the cAMP response element-binding protein (CREB), brain-derived neurotrophic factor (BDNF), and cFos were evaluated in the corticolimbic regions. The results showed that pre-test administration of fluoxetine (3 and 5 mg/kg, i.p.) improved tamoxifen-induced memory impairment in the passive avoidance learning task. Pre-test bilateral microinjection of D-AP5, a selective NMDA receptor antagonist, into the dorsal hippocampal CA1 regions and the central amygdala (CeA), but not the medial prefrontal cortex (mPFC), inhibited the improving effect of fluoxetine on tamoxifen response. It is important to note that the microinjection of D-AP5 into the different sites by itself did not affect memory retrieval. Memory retrieval increased the signaling pathway of pCREB/CREB/BDNF/cFos in the corticolimbic regions. Tamoxifen-induced memory impairment decreased the hippocampal/PFC BDNF level and the amygdala level of pCREB/CREB/cFos. The improving effect of fluoxetine on tamoxifen significantly increased the hippocampal/PFC expression levels of BDNF, the PFC/amygdala expression levels of cFos, and the ratio of pCREB/CREB in all targeted areas. Thus, NMDA receptors' activity in the different corticolimbic regions mediates fluoxetine/tamoxifen memory retrieval. The corticolimbic synaptic plasticity changes likely accompany the improving effect of fluoxetine on tamoxifen response.

Crocin molecular signaling pathways at a glance: A comprehensive review

Crocin is a hydrophilic carotenoid that is synthesized in the flowers of the Crocus genus. Numerous in vitro and in vivo research projects have been published about the biological and pharmacological properties and toxicity of crocin. Crocin acts as a memory enhancer, anxiolytic, aphrodisiac, antidepressant, neuroprotective, and so on. Here, we introduce an updated and comprehensive review of crocin molecular mechanisms based on previously examined and mentioned in the literature. Different studies confirmed the significant effect of crocin to control pathological conditions, including oxidative stress, inflammation, metabolic disorders, neurodegenerative disorders, and cancer. The neuroprotective effect of crocin could be related to the activation of phosphatidylinositol 3-kinase/protein kinase B (PI3K/AKT)/mammalian target of rapamycin (mTOR), Notch, and cyclic-AMP response element-binding protein signaling pathways. The crocin also protects the cardiovascular system through the inhibitory effect on toll-like receptors. The regulatory effect of crocin on PI3K/AKT/mTOR, AMP-activated protein kinase, mitogen-activated protein kinases (MAPK), and peroxisome proliferator-activated receptor pathways can play an effective role in the treatment of metabolic disorders. The crocin has anticancer activity through the PI3K/AKT/mTOR, MAPK, vascular endothelial growth factor, Wnt/β-catenin, and Janus kinases-signal transducer and activator of transcription suppression. Also, the nuclear factor-erythroid factor 2-related factor 2 and p53 signaling pathway activation may be effective in the anticancer effect of crocin. Finally, among signaling pathways regulated by crocin, the most important ones seem to be those related to the regulatory effect on the PI3K/AKT/mTOR pathway.

Ninjinyoeito improves social behavior disorder in neuropeptide Y deficient zebrafish

Sociability is an essential component of the linkage structure in human and other vertebrate communication. Low sociability is defined as a poor social approach, including social withdrawal and apathy, and is implicated in a variety of psychiatric disorders. Ninjinyoeito (NYT), a traditional Japanese herbal medicine, has been used in the medical field. This study aimed to determine the effect of NYT on low sociality in NPY-KO zebrafish. NPY-KO zebrafish were fed a 3% NYT-supplemented diet for 4 days and subjected to behavioral tests. In the mirror test, NPY-KO zebrafish fed a control diet showed avoidance behavior toward their mirror counterparts. In contrast, the treatment of NPY-KO zebrafish with NYT significantly increased their interaction with their counterparts in the mirror. In addition, a 3-chambers test was conducted to confirm the effect of NYT on the low sociality of NPY-KO zebrafish. NPY-KO zebrafish fed the control diet showed less interaction with fish chambers, while NYT treatment increased the interaction. Phosphorylation of ERK, a marker of neuronal activity, was significantly reduced in the whole brain of NYT-fed NPY-KO zebrafish, compared to the control diet. NYT treatment significantly suppressed hypothalamic-pituitary-adrenal-related genes (gr, pomc, and crh) and sympathetic-adrenal-medullary-related genes (th1, th2, and cck) in NPY-KO zebrafish. NYT administration significantly reduced mRNA levels of gad1b compared to the control diet, suggesting the involvement of GABAergic neurons in NYT-induced improvement of low sociability. Furthermore, the expression of CREB was suppressed when NPY-KO zebrafish were fed NYT. Next, we attempted to identify the effective herb responsible for the NYT-induced improvement of low sociability. NPY-KO zebrafish were fed an experimental diet containing the target herb for 4 days, and its effect on sociability was evaluated using the 3-chambers test. Results showed that Cinnamon Bark and Polygala Root treatments significantly increased time spent in the fish tank area compared to the control diet, while the other 10 herbs did not. We confirmed that these two herbs suppressed the activity of HPA-, SAM-, and GABAergic neurons, as well as NYT-treated zebrafish, accompanied by downregulation of CREB signaling. This study suggests the potential use of NYT as a drug for sociability disorders.

Effects and Mechanism of Particulate Matter on Tendon Healing Based on Integrated Analysis of DNA Methylation and RNA Sequencing Data in a Rat Model

Exposure to particulate matter (PM) has been linked with the severity of various diseases. To date, there is no study on the relationship between PM exposure and tendon healing. Open Achilles tenotomy of 20 rats was performed. The animals were divided into two groups according to exposure to PM: a PM group and a non-PM group. After 6 weeks of PM exposure, the harvest and investigations of lungs, blood samples, and Achilles tendons were performed. Compared to the non-PM group, the white blood cell count and tumor necrosis factor-alpha expression in the PM group were significantly higher. The Achilles tendons in PM group showed significantly increased inflammatory outcomes. A TEM analysis showed reduced collagen fibrils in the PM group. A biomechanical analysis demonstrated that the load to failure value was lower in the PM group. An upregulation of the gene encoding cyclic AMP response element-binding protein (CREB) was detected in the PM group by an integrated analysis of DNA methylation and RNA sequencing data, as confirmed via a Western blot analysis showing significantly elevated levels of phosphorylated CREB. In summary, PM exposure caused a deleterious effect on tendon healing. The molecular data indicate that the action mechanism of PM may be associated with upregulated CREB signaling.

Network Biology Approaches to Uncover Therapeutic Targets Associated with Molecular Signaling Pathways from circRNA in Postoperative Cognitive Dysfunction Pathogenesis

Postoperative cognitive dysfunction (POCD) is a cognitive deterioration and dementia that arise after a surgical procedure, affecting up to 40% of surgery patients over the age of 60. The precise etiology and molecular mechanisms underlying POCD remain uncovered. These reasons led us to employ integrative bioinformatics and machine learning methodologies to identify several biological signaling pathways involved and molecular signatures to better understand the pathophysiology of POCD. A total of 223 differentially expressed genes (DEGs) comprising 156 upregulated and 67 downregulated genes were identified from the circRNA microarray dataset by comparing POCD and non-POCD samples. Gene ontology (GO) analyses of DEGs were significantly involved in neurogenesis, autophagy regulation, translation in the postsynapse, modulating synaptic transmission, regulation of the cellular catabolic process, macromolecule modification, and chromatin remodeling. Pathway enrichment analysis indicated some key molecular pathways, including mTOR signaling pathway, AKT phosphorylation of cytosolic targets, MAPK and NF-κB signaling pathway, PI3K/AKT signaling pathway, nitric oxide signaling pathway, chaperones that modulate interferon signaling pathway, apoptosis signaling pathway, VEGF signaling pathway, cellular senescence, RANKL/RARK signaling pathway, and AGE/RAGE pathway. Furthermore, seven hub genes were identified from the PPI network and also determined transcription factors and protein kinases. Finally, we identified a new predictive drug for the treatment of SCZ using the LINCS L1000, GCP, and P100 databases. Together, our results bring a new era of the pathogenesis of a deeper understanding of POCD, identified novel therapeutic targets, and predicted drug inhibitors in POCD.

GABAA receptor agonist suppresses pediatric medulloblastoma progression by inhibiting PKA-Gli1 signaling axis

The Sonic hedgehog-activated subgroup of medulloblastoma (SHH-MB) is one of the most common malignant pediatric brain tumors. Recent clinical studies and genomic databases indicate that GABAA receptor holds significant clinical relevance as a therapeutic target for pediatric MB. Herein, we report that "moxidectin," a GABAA receptor agonist, inhibits the proliferation of Daoy, UW426, UW228, ONS76, and PFSK1 SHH-MB cells by inducing apoptosis. Immunoblotting and immunofluorescence microscopy demonstrated that moxidectin significantly induced GABAA receptor expression and inhibited cyclic AMP (cAMP)-mediated protein kinase A (PKA)-cAMP response element-binding protein (CREB)-Gli1 signaling in SHH-MB. Gli1 and the downstream effector cancer stem cell (CSC) molecules such as Pax6, Oct4, Sox2, and Nanog were also inhibited by moxidectin treatment. Interestingly, moxidectin also inhibited the expression of MDR1. Mechanistic studies using pharmacological or genetic inhibitors/activators of PKA and Gli1 confirmed that the anti-proliferative and apoptotic effects of moxidectin were mediated through inhibition of PKA-Gli1 signaling. Oral administration of 2.5 mg/kg moxidectin suppressed the growth of SHH-MB tumors by 55%-80% in subcutaneous and intracranial tumor models in mice. Ex vivo analysis of excised tumors confirmed the observations made in the in vitro studies. Moxidectin is an FDA-approved drug with an established safety record, therefore any positive findings from our studies will prompt its further clinical investigation for the treatment of MB patients.

ERRγ Ligand Regulates Adult Neurogenesis and Depression-like Behavior in a LRRK2-G2019S-associated Young Female Mouse Model of Parkinson's Disease

Adult neurogenesis, a process controlling the proliferation to maturation of newly generated neurons in the post-developmental brain, is associated with various brain functions and pathogenesis of neuropsychological diseases, such as Parkinson's disease (PD) and depression. Because orphan nuclear receptor estrogen-related receptor γ (ERRγ) plays a role in the differentiation of neuronal cells, we investigated whether an ERRγ ligand enhances adult neurogenesis and regulates depressive behavior in a LRRK2-G2019S-associated mouse model of PD. Young female LRRK2-G2019S mice (7-9 weeks old) showed depression-like behavior without dopaminergic neuronal loss in the nigrostriatal pathway nor motor dysfunction. A significant decrease in adult hippocampal neurogenesis was detected in young female LRRK2-G2019S mice, but not in comparable male mice. A synthetic ERRγ ligand, (E)-4-hydroxy-N'-(4-(phenylethynyl)benzylidene)benzohydrazide (HPB2), ameliorated depression-like behavior in young female LRRK2-G2019S mice and enhanced neurogenesis in the hippocampus, as evidenced by increases in the number of bromodeoxyuridine/neuronal nuclei-positive cells and in the intensity and number of doublecortin-positive cells in the hippocampal dentate gyrus (DG). Moreover, HPB2 significantly increased the number of spines and the number and length of dendrites in the DG of young female LRRK2-G2019S mice. Furthermore, HPB2 upregulated brain-derived neurotrophic factor (BDNF)/tropomyosin receptor kinase B (TrkB) signaling, one of the important factors regulating neurogenesis, as well as phosphorylated cAMP-response element binding protein-positive cells in the DG of young female LRRK2-G2019S mice. Together, these results suggest ERRγ as a novel therapeutic target for PD-associated depression by modulating adult neurogenesis and BDNF/TrkB signaling.

Neuroprotective effects of ex vivo-expanded regulatory T cells on trimethyltin-induced neurodegeneration in mice

Background

Trimethyltin (TMT) is a potent neurotoxicant that leads to hippocampal neurodegeneration. Regulatory T cells (Tregs) play an important role in maintaining the immune balance in the central nervous system (CNS), but their activities are impaired in neurodegenerative diseases. In this study, we aimed to determine whether adoptive transfer of Tregs, as a living drug, ameliorates hippocampal neurodegeneration in TMT-intoxicated mice.

Methods

CD4⁺CD25⁺ Tregs were expanded in vitro and adoptively transferred to TMT-treated mice. First, we explored the effects of Tregs on behavioral deficits using the Morris water maze and elevated plus maze tests. Biomarkers related to memory formation, such as cAMP response element-binding protein (CREB), protein kinase C (PKC), neuronal nuclear protein (NeuN), nerve growth factor (NGF), and ionized calcium binding adaptor molecule 1 (Iba1) in the hippocampus were examined by immunohistochemistry after killing the mouse. To investigate the neuroinflammatory responses, the polarization status of microglia was examined in vivo and in vitro using real-time reverse transcription polymerase chain reaction (rtPCR) and Enzyme-linked immunosorbent assay (ELISA). Additionally, the inhibitory effects of Tregs on TMT-induced microglial activation were examined using time-lapse live imaging in vitro with an activation-specific fluorescence probe, CDr20.

Results

Adoptive transfer of Tregs improved spatial learning and memory functions and reduced anxiety in TMT-intoxicated mice. Additionally, adoptive transfer of Tregs reduced neuronal loss and recovered the expression of neurogenesis enhancing molecules in the hippocampi of TMT-intoxicated mice. In particular, Tregs inhibited microglial activation and pro-inflammatory cytokine release in the hippocampi of TMT-intoxicated mice. The inhibitory effects of TMT were also confirmed via in vitro live time-lapse imaging in a Treg/microglia co-culture system.

Conclusions

These data suggest that adoptive transfer of Tregs ameliorates disease progression in TMT-induced neurodegeneration by promoting neurogenesis and modulating microglial activation and polarization.

Bupleurum chinense DC improves CUMS-induced depressive symptoms in rats through upregulation of the cAMP/PKA/CREB signalling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Bupleurum chinense DC. (B. chinense) is the dried root of B. chinense, belonging to the Umbelliferae family. B. chinense has been reported since ancient times for its effect of soothing the liver and relieving depression. Additionally, its important role in treating depression, depressed mood disorders and anti-inflammation has been proven in previous studies. However, its specific mechanism of action remains unknown.

AIM OF THE STUDY

The key targets and metabolites of the antidepressant effect of B. chinense were investigated based on the cAMP signalling pathway. The study examined the mechanism for the antidepressant effect of B. chinense by target prediction, analysis of related metabolites and potential metabolic pathways.

MATERIALS AND METHODS

A network pharmacology approach was used to predict the antidepressant targets and pathways of B. chinense. A depression rat model was established through the CUMS (chronic unpredictable mild stress) procedure. The depression model was assessed by body weight, sugar-water preference, water maze and enzyme-linked immunosorbent assay (ELISA) indicators (5hydroxytryptamine, etc.). The key metabolic pathways were screened by correlations between metabolites and key targets. Finally, a quantitative analysis of key targets and metabolites was experimentally validated.

RESULTS

B. chinense significantly ameliorated the reduction in body weight, sugar-water preference rate and cognitive performance in the water maze experiment in rats with depression induced by CUMS. ELISA, Western blotting (WB) and reverse transcription-polymerase chain reaction (RT-PCR) assays showed that B. chinense significantly improves the expression of protein kinase cyclic adenylic acid (cAMP)-activated catalytic subunit alpha (PRKACA), cAMP-response element-binding protein (CREB) and cAMP activation in the rat brain induced by CUMS. According to metabolic pathway analysis, B. chinense shows an antidepressant effect primarily by regulating the cAMP metabolic pathway.

CONCLUSION

B. chinense upregulated PRKACA and CREB expression and the level of the key metabolite cAMP in the cAMP/PKA/CREB pathway while reducing the inflammatory response to depression treatment. These new findings support future research on the antidepressant effects of B. chinense.

Potential role of IP3/Ca2+ signaling and phosphodiesterases: Relevance to neurodegeneration in Alzheimer's disease and possible therapeutic strategies

Despite large investments by industry and governments, no disease-modifying medications for the treatment of patients with Alzheimer's disease (AD) have been found. The failures of various clinical trials indicate the need for a more in-depth understanding of the pathophysiology of AD and for innovative therapeutic strategies for its treatment. Here, we review the rational for targeting IP3 signaling, cytosolic calcium dysregulation, phosphodiesterases (PDEs), and secondary messengers like cGMP and cAMP, as well as their correlations with the pathophysiology of AD. Various drugs targeting these signaling cascades are still in pre-clinical and clinical trials which support the ideas presented in this article. Further, we describe different molecular mechanisms and medications currently being used in various pre-clinical and clinical trials involving IP3/Ca⁺² signaling. We also highlight various isoforms, as well as the functions and pharmacology of the PDEs broadly expressed in different parts of the brain and attempt to unravel the potential benefits of PDE inhibitors for use as novel medications to alleviate the pathogenesis of AD.

Loss-of-function variants in the schizophrenia risk gene SETD1A alter neuronal network activity in human neurons through the cAMP/PKA pathway

Heterozygous loss-of-function (LoF) mutations in SETD1A, which encodes a subunit of histone H3 lysine 4 methyltransferase, cause a neurodevelopmental syndrome and increase the risk for schizophrenia. Using CRISPR-Cas9, we generate excitatory/inhibitory neuronal networks from human induced pluripotent stem cells with a SETD1A heterozygous LoF mutation (SETD1A+/-). Our data show that SETD1A haploinsufficiency results in morphologically increased dendritic complexity and functionally increased bursting activity. This network phenotype is primarily driven by SETD1A haploinsufficiency in glutamatergic neurons. In accordance with the functional changes, transcriptomic profiling reveals perturbations in gene sets associated with glutamatergic synaptic function. At the molecular level, we identify specific changes in the cyclic AMP (cAMP)/Protein Kinase A pathway pointing toward a hyperactive cAMP pathway in SETD1A+/- neurons. Finally, by pharmacologically targeting the cAMP pathway, we are able to rescue the network deficits in SETD1A+/- cultures. Our results demonstrate a link between SETD1A and the cAMP-dependent pathway in human neurons.

An epigenetic association analysis of childhood trauma in psychosis reveals possible overlap with methylation changes associated with PTSD

Patients with a severe mental disorder report significantly higher levels of childhood trauma (CT) than healthy individuals. Studies have suggested that CT may affect brain plasticity through epigenetic mechanisms and contribute to developing various psychiatric disorders. We performed a blood-based epigenome-wide association study using the Childhood Trauma Questionnaire-short form in 602 patients with a current severe mental illness, investigating DNA methylation association separately for five trauma subtypes and the total trauma score. The median trauma score was set as the predefined cutoff for determining whether the trauma was present or not. Additionally, we compared our genome-wide results with methylation probes annotated to candidate genes previously associated with CT. Of the patients, 83.2% reported CT above the cutoff in one or more trauma subtypes, and emotional neglect was the trauma subtype most frequently reported. We identified one significant differently methylated position associated with the gene TANGO6 for physical neglect. Seventeen differentially methylated regions (DMRs) were associated with different trauma categories. Several of these DMRs were annotated to genes previously associated with neuropsychiatric disorders such as post-traumatic stress disorder and cognitive impairments. Our results support a biomolecular association between CT and severe mental disorders. Genes that were previously identified as differentially methylated in CT-exposed subjects with and without psychosis did not show methylation differences in our analysis. We discuss this inconsistency, the relevance of our findings, and the limitations of our study.

Hyperbaric Oxygen Therapy Improves Parkinson’s Disease by Promoting Mitochondrial Biogenesis via the SIRT-1/PGC-1α Pathway

Hyperbaric oxygen therapy (HBOT) has been suggested as a potential adjunctive therapy for Parkinson’s disease (PD). PD is a neurodegenerative disease characterized by the progressive loss of dopaminergic neurons in the substantia nigra pars compacta (SNpc). The aim of this study was to investigate the protective mechanisms of HBOT on neurons and motor function in a 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model of PD and 1-methyl-4-phenylpyridinium (MPP⁺)-mediated neurotoxicity in SH-SY5Y cells on the potential protective capability. In vivo: male C57BL/6 mice were randomly divided into three groups: control, MPTP group and MPTP+HBOT group. The MPTP-treated mice were intraperitoneally received MPTP (20 mg/kg) four times at 2 h intervals within a day. The day after MPTP treatment, MPTP+HBOT mice were exposed to hyperbaric oxygen at 2.5 atmosphere absolute (ATA) with 100% oxygen for 1 h once daily for 7 consecutive days. In vitro: retinoic acid (RA)-differentiated SH-SY5Y cells were treated with MPP⁺ for 1 h followed by hyperbaric oxygen at 2.5 ATA with 100% oxygen for 1 h. The results showed that MPTP induced a significant loss in tyrosine hydroxylase (TH)-positive neurons in the SNpc of mice. HBOT treatment significantly increased the number of TH-positive neurons, with enhanced neurotrophic factor BDNF, decreased apoptotic signaling and attenuated inflammatory mediators in the midbrain of MPTP-treated mice. In addition, MPTP treatment decreased the locomotor activity and grip strength of mice, and these effects were shown to improve after HBOT treatment. Furthermore, MPTP decreased mitochondrial biogenesis signaling (SIRT-1, PGC-1α and TFAM), as well as mitochondrial marker VDAC expression, while HBOT treatment was shown to upregulate protein expression. In cell experiments, MPP⁺ reduced neurite length, while HBOT treatment attenuated neurite retraction. Conclusions: the effects of HBOT in MPTP-treated mice might come from promoting mitochondrial biogenesis, decreasing apoptotic signaling and attenuating inflammatory mediators in the midbrain, suggesting its potential benefits in PD treatment.

Receptor-Mediated AKT/PI3K Signalling and Behavioural Alterations in Zebrafish Larvae Reveal Association between Schizophrenia and Opioid Use Disorder

The link between substance abuse and the development of schizophrenia remains elusive. In this study, we assessed the molecular and behavioural alterations associated with schizophrenia, opioid addiction, and opioid withdrawal using zebrafish as a biological model. Larvae of 2 days post fertilization (dpf) were exposed to domperidone (DMP), a dopamine-D2 dopamine D2 receptor antagonist, and morphine for 3 days and 10 days, respectively. MK801, an N-methyl-D-aspartate (NMDA) receptor antagonist, served as a positive control to mimic schizophrenia-like behaviour. The withdrawal syndrome was assessed 5 days after the termination of morphine treatment. The expressions of schizophrenia susceptibility genes, i.e., pi3k, akt1, slc6a4, creb1 and adamts2, in brains were quantified, and the levels of whole-body cyclic adenosine monophosphate (cAMP), serotonin and cortisol were measured. The aggressiveness of larvae was observed using the mirror biting test. After the short-term treatment with DMP and morphine, all studied genes were not differentially expressed. As for the long-term exposure, akt1 was downregulated by DMP and morphine. Downregulation of pi3k and slc6a4 was observed in the morphine-treated larvae, whereas creb1 and adamts2 were upregulated by DMP. The levels of cAMP and cortisol were elevated after 3 days, whereas significant increases were observed in all of the biochemical tests after 10 days. Compared to controls, increased aggression was observed in the DMP-, but not morphine-, treated group. These two groups showed reduction in aggressiveness when drug exposure was prolonged. Both the short- and long-term morphine withdrawal groups showed downregulation in all genes examined except creb1, suggesting dysregulated reward circuitry function. These results suggest that biochemical and behavioural alterations in schizophrenia-like symptoms and opioid dependence could be controlled by common mechanisms.

miR-542-3p-Targeted PDE4D Regulates cAMP/PKA Signaling Pathway and Improves Cardiomyocyte Injury

Objective

To investigate the protective effect of miR-542-3p on cardiomyocyte injury and related mechanisms.

Methods

A cardiomyocyte hypoxia/reoxygenation model was established. The expression levels of miR-542-3p and PDE4D were detected using qRT-PCR; the luciferase reporter assay system was used to detect the targeting relationship between miR-542-3p and PDE4D; overexpressing miR-542-3p was transfected into cardiomyocytes, and ROS release was detected by immunofluorescence while cellular apoptosis was detected by TUNEL; and the western blot assay was applied to detect the expression of PDE4D, phosphorylated protein kinase A (p-PKA), and phosphorylated cyclic adenosine monophosphate (cAMP) response element-binding protein (p-CREB).

Results

Compared with the control group, the miR-542-3p expression level was decreased and the PDE4D expression level was increased in the cardiomyocyte hypoxia/reoxygenation model group. The dual-luciferase reporter assay system confirmed that miR-542-3p could target and regulate PDE4D; the transfection with cardiomyocytes using the overexpressing miR-542-3p could downregulate PDE4D expression, attenuate ROS release during cardiomyocyte injury, and reduce cellular apoptosis rate, while upregulating the expression of p-PKA and p-CREB.

Conclusion

The miR-542-3p can negatively regulate PDE4D protein expression and attenuate cardiomyocyte injury through a mechanism related to the activation of the cAMP/PKA signaling pathway.

Upscaling biological complexity to boost neuronal and oligodendroglia maturation and improve in vitro developmental neurotoxicity (DNT) evaluation

Human induced pluripotent stem cell (iPSC)-derived neuronal and glial cell models are suitable to assess the effects of environmental chemicals on the developing brain. Such test systems can recapitulate several key neurodevelopmental features, such as neural stem cell formation and differentiation towards different neuronal subtypes and astrocytes, neurite outgrowth, synapse formation and neuronal network formation and function, which are crucial for brain development. While monolayer, two-dimensional (2D) cultures of human iPSC-neuronal or glial derivatives are generally suited for high-throughput testing, they also show some limitations. In particular, differentiation towards myelinating oligodendrocytes can only be achieved after extended periods in differentiation. In recent years, the implementation of three-dimensional (3D) neuronal and glial models obtained from human iPSCs has been shown to compensate for such limitations, enabling robust differentiation towards both neuronal and glial cell populations, myelination and formation of more mature neuronal network activity. Here we compared the differentiation capacity of human iPSC-derived neural stem cells cultured either as 2D monolayer or as 3D neurospheres, and assessed chlorpyrifos (CPF) effects. Data indicate that 3D neurospheres differentiate towards neurons and oligodendroglia more rapidly than 2D cultures; however, the 2D model is more suitable to assess neuronal functionality by analysis of spontaneous electrical activity using multielectrode array. Moreover, 2D and 3D test systems are diversely susceptible to CPF treatment. In conclusion, the selection of the most suitable in vitro test system (either 2D or 3D) should take into account the context of use and intended research goals ('fit for purpose' principle).

Counteracting epigenetic mechanisms regulate the structural development of neuronal circuitry in human neurons

Autism spectrum disorders (ASD) are associated with defects in neuronal connectivity and are highly heritable. Genetic findings suggest that there is an overrepresentation of chromatin regulatory genes among the genes associated with ASD. ASH1 like histone lysine methyltransferase (ASH1L) was identified as a major risk factor for ASD. ASH1L methylates Histone H3 on Lysine 36, which is proposed to result primarily in transcriptional activation. However, how mutations in ASH1L lead to deficits in neuronal connectivity associated with ASD pathogenesis is not known. We report that ASH1L regulates neuronal morphogenesis by counteracting the catalytic activity of Polycomb Repressive complex 2 group (PRC2) in stem cell-derived human neurons. Depletion of ASH1L decreases neurite outgrowth and decreases expression of the gene encoding the neurotrophin receptor TrkB whose signaling pathway is linked to neuronal morphogenesis. The neuronal morphogenesis defect is overcome by inhibition of PRC2 activity, indicating that a balance between the Trithorax group protein ASH1L and PRC2 activity determines neuronal morphology. Thus, our work suggests that ASH1L may epigenetically regulate neuronal morphogenesis by modulating pathways like the BDNF-TrkB signaling pathway. Defects in neuronal morphogenesis could potentially impair the establishment of neuronal connections which could contribute to the neurodevelopmental pathogenesis associated with ASD in patients with ASH1L mutations.

Improved cognition impairment by activating cannabinoid receptor type 2: Modulating CREB/BDNF expression and impeding TLR-4/NFκBp65/M1 microglia signaling pathway in D-galactose-injected ovariectomized rats

Alzheimer's disease (AD) is characterized by an active inflammatory response induced by the brain's deposition and accumulation of amyloid-beta (Aβ). Cannabinoid receptor type 2 (CB2R) is expressed in specific brain areas, modulating functions, and pathophysiologies in CNS. Herein, we aimed to evaluate whether activation of CB2R can improve the cognitive impairment in the experimental AD-like model and determine the involved intracellular signaling pathway. Injection of D-galactose (150 mg/kg, i.p.) was performed to urge AD-like features in bilaterally ovariectomized female rats (OVC/D-gal rats) for 8-weeks. Then, AM1241, a CB2R-agonist (3 and 6 mg/kg), was injected intraperitoneally starting from the 6th week. Treatment with AM1241, significantly down-regulated; Toll-like receptor4 (TLR4), Myd88 (TLR4-adaptor protein) genes expression, and the pro-inflammatory cytokines (NFκB p65, TNF-α, IL-6, and IL-12). In contrast, it enhanced BDNF (the brain-derived neurotrophic factor) and CREB (the cyclic AMP response element-binding protein) as well as the immune-modulatory cytokines (IL-4 and IL-10) levels. Moreover, AM1241 lessened the immune-expression of GFAP, CD68, caspase-3, and NFκB p65 markers and mended the histopathological damage observed in OVC/D-gal rats by decreasing the deposition of amyloid plaques and degenerative neuronal lesions, as well as improving their recognition and learning memory in both novel object recognition and Morris water maze tests. In conclusion, activating CB2R by the selective agonist AM1241 can overrun cognitive deficits in OVC/D-gal rats through modulation of TLR4/ NFκB p65 signaling, mediated by modulating CREB/BDNF pathway, thereby can be applied as a potential therapeutic strategy in AD treatment.

Disruption of 5-hydroxytryptamine 1A receptor and orexin receptor 1 heterodimer formation affects novel G protein-dependent signaling pathways and has antidepressant effects in vivo

G protein-coupled receptor (GPCR) heterodimers are new targets for the treatment of depression. Increasing evidence supports the importance of serotonergic and orexin-producing neurons in numerous physiological processes, possibly via a crucial interaction between 5-hydroxytryptamine 1A receptor (5-HT1AR) and orexin receptor 1 (OX1R). However, little is known about the function of 5-HT1AR/OX1R heterodimers. It is unclear how the transmembrane domains (TMs) of the dimer affect its function and whether its modulation mediates antidepressant-like effects. Here, we examined the mechanism of 5-HT1AR/OX1R dimerization and downstream G protein-dependent signaling. We found that 5-HT1AR and OX1R form constitutive heterodimers that induce novel G protein-dependent signaling, and that this heterodimerization does not affect recruitment of β-arrestins to the complex. In addition, we found that the structural interface of the active 5-HT1AR/OX1R dimer transforms from TM4/TM5 in the basal state to TM6 in the active conformation. We also used mutation analyses to identify key residues at the interface (5-HT1AR R151^4.40, 5-HT1AR Y198^5.41, and OX1R L230^5.54). Injection of chronic unpredictable mild stress (CUMS) rats with TM4/TM5 peptides improved their depression-like emotional status and decreased the number of endogenous 5-HT1AR/OX1R heterodimers in the rat brain. These antidepressant effects may be mediated by upregulation of BDNF levels and enhanced phosphorylation and activation of CREB in the hippocampus and medial prefrontal cortex. This study provides evidence that 5-HT1AR/OX1R heterodimers are involved in the pathological process of depression. Peptides including TMs of the 5-HT1AR/OX1R heterodimer interface are candidates for the development of compounds with fast-acting antidepressant-like effects.

The COVID-19 Cell Signalling Problem: Spike, RAGE, PKC, p38, NFκB & IL-6 Hyper-Expression and the Human Ezrin Peptide, VIP, PKA-CREB Solution

SARS-CoV-2 infection inhibits interferon expression, while hyper-activating innate-immune signalling and expression of pro-inflammatory cytokines. SARS-CoV-2 proteins: Spike, M and nsp6, nsp12 and nsp13 inhibit IFR3-mediated Type-1-interferon defence, but hyper-activate intracellular signalling, which leads to dysfunctional expression of pro-inflammatory cytokines, particularly IL-1β IL-6, IL-8, and TNFα. Ezrin, a sub-membrane adaptor-protein, organises multi-protein-complexes such as ezrin+NHERF1+NHE+CFTR, which control the density and location of ACE2 receptor expression on the luminal surface of airway-epithelial-cells, as well as determining susceptibility to SARS-CoV-2 infection. This protein complex is vital for lung-surfactant production for efficient gas-exchange. Ezrin also forms multi-protein-complexes that regulate signalling kinases; Ras, PKC, PI3K, and PKA. m-RAGE is a pattern-recognition-receptor of the innate immune system that is triggered by AGEs, which are chemically modified proteins common in the elderly and obese. m-RAGE forms multi-protein complexes with ezrin and TIRAP, a toll-like-receptor adaptor-protein. The main cause of COVID-19 is not viral infection but pro-inflammatory p38MAPK signalling mediated by TLRs and RAGE. In contrast, it appears that activated ezrin+PKA signalling results in the activation of transcription-factor CREB, which suppresses NFκB mediated pro-inflammatory cytokine expression. In addition, competition between ezrin and TIRAP to form multi-protein-complexes on membrane PIP2-lipid-rafts is a macromolecular-switch that changes the priority from innate immune activation programs to adaptive immune activation programs. Human Vasoactive Intestinal Peptide (VIP), and Human Ezrin Peptides (HEP-1 and RepG3) probably inhibit COVID-19 by activating the ezrin+PKA and ras>Raf>MEK>ERK>RSK>CREB>IL-10 signalling, which favours activation of adaptive immunity programs and inhibition of the dysfunctional innate-inflammation, the cause of COVID-19. HEP-1, RepG3, and VIP in individual human volunteers and in small clinical studies have been shown to be effective COVID-19 therapies, and seem to have a closely related mechanism of action.

Natural Cyclooxygenase-2 Inhibitors Synergize With Butyrate to Augment Chicken Host Defense Peptide Gene Expression

Enhancing the synthesis of microbicidal and immunomodulatory host defense peptides (HDP) is a promising host-directed antimicrobial strategy to combat a growing threat of antimicrobial resistance. Here we investigated the effect of several natural cyclooxygenase-2 (COX-2) inhibitors on chicken HDP gene regulation. Our results indicated that phenolic COX-2 inhibitors such as quercetin, resveratrol, epigallocatechin gallate, anacardic acid, and garcinol enhanced HDP gene expression in chicken HTC macrophage cell line and peripheral blood mononuclear cells (PBMCs). Moreover, these natural COX-2 inhibitors showed a strong synergy with butyrate in augmenting the expressions of multiple HDP genes in HTC cells and PBMCs. Additionally, quercetin and butyrate synergistically promoted the expressions of mucin-2 and claudin-1, two major genes involved in barrier function, while suppressing lipopolysaccharide-triggered interleukin-1β expression in HTC macrophages. Mechanistically, we revealed that NF-κB, p38 mitogen-activated protein kinase, and cyclic adenosine monophosphate signaling pathways were all involved in the avian β-defensin 9 gene induction, but histone H4 was not hyperacetylated in response to a combination of butyrate and quercetin. Because of their HDP-inducing, barrier-protective, and antiinflammatory activities, these natural COX-2 inhibitors, when combined with butyrate, may be developed as novel host-directed antimicrobial therapeutics.

Discovery of new ERRγ agonists regulating dopaminergic neuronal phenotype in SH-SY5Y cells

The discovery of small molecules that regulate specific neuronal phenotypes is important for the development of new therapeutic candidates for neurological diseases. Estrogen-related receptor γ (ERRγ), an orphan nuclear receptor widely expressed in the central nervous system (CNS), is closely related to the regulation of neuronal metabolism and differentiation. We previously reported that upregulation of ERRγ could enhance dopaminergic neuronal phenotypes in the neuroblastoma cell line, SH-SY5Y. In this study, we designed and synthesized a series of new ERRγ agonists using the X-ray crystal structure of the GSK4716-bound ERRγ complex and known synthetic ligands. Our new ERRγ agonists exhibited increased transcriptional activities of ERRγ. In addition, our molecular docking results supported the experimental findings for ERRγ agonistic activity of the potent analogue, 5d. Importantly, 5d not only enhanced the expression of dopaminergic neuronal-specific molecules, TH and DAT but also activated the relevant signaling events, such as the CREB-mediated signaling pathway. The results of the present study may provide useful clues for the development of novel ERRγ agonists for neurological diseases related to the dopaminergic nervous system.

Nuclear-Mitochondrial Interactions

Mitochondria, the cell’s major energy producers, also act as signaling hubs, interacting with other organelles both directly and indirectly. Despite having its own circular genome, the majority of mitochondrial proteins are encoded by nuclear DNA. To respond to changes in cell physiology, the mitochondria must send signals to the nucleus, which can, in turn, upregulate gene expression to alter metabolism or initiate a stress response. This is known as retrograde signaling. A variety of stimuli and pathways fall under the retrograde signaling umbrella. Mitochondrial dysfunction has already been shown to have severe implications for human health. Disruption of retrograde signaling, whether directly associated with mitochondrial dysfunction or cellular environmental changes, may also contribute to pathological deficits. In this review, we discuss known signaling pathways between the mitochondria and the nucleus, examine the possibility of direct contacts, and identify pathological consequences of an altered relationship.

Allosteric Modulation of the Sigma-1 Receptor Elicits Antipsychotic-like Effects

Allosteric modulation represents an important approach in drug discovery because of its advantages in safety and selectivity. SOMCL-668 is the first selective and potent sigma-1 receptor allosteric modulator, discovered in our laboratory. The present work investigates the potential therapeutic effects of SOMCL-668 on phencyclidine (PCP)-induced schizophrenia-related behavior in mice and further elucidates underlying mechanisms for its antipsychotic-like effects. SOMCL-668 not only attenuated acute PCP-induced hyperactivity and PPI disruption, but also ameliorated social deficits and cognitive impairment induced by chronic PCP treatment. Pretreatment with the selective sigma-1 receptor antagonist BD1047 blocked the effects of SOMCL-668, indicating sigma-1 receptor-mediated responses. This was confirmed using sigma-1 receptor knockout mice, in which SOMCL-668 failed to ameliorate PPI disruption and hyperactivity induced by acute PCP and social deficits and cognitive impairment induced by chronic PCP treatment. Additionally, in vitro SOMCL-668 exerted positive modulation of sigma-1 receptor agonist-induced intrinsic plasticity in brain slices recorded by patch-clamp. Furthermore, in vivo lower dose of SOMCL-668 exerted positive modulation of improvement in social deficits and cognitive impairment induced by the selective sigma-1 agonist PRE084. Also, SOMCL-668 reversed chronic PCP-induced down-regulation in expression of frontal cortical p-AKT/AKT, p-CREB/CREB and BDNF in wide-type but not sigma-1 knockout mice. Moreover, administration of the PI3K/AKT inhibitor LY294002 abolished amelioration by SOMCL-668 of chronic PCP-induced schizophrenia-related behaviors by inhibition of BDNF expression. The present data provide initial, proof-of-concept evidence that allosteric modulation of the sigma-1 receptor may be a novel approach for the treatment of psychotic illness.

Capsaicin and Zinc Promote Glucose Uptake in C2C12 Skeletal Muscle Cells through a Common Calcium Signalling Pathway

Capsaicin and zinc have recently been highlighted as potential treatments for glucose metabolism disorders; however, the effect of these two natural compounds on signalling pathways involved in glucose metabolism is still uncertain. In this study, we assessed the capsaicin- or zinc- induced activation of signalling molecules including calcium/calmodulin-dependent protein kinase 2 (CAMKK2), cAMP-response element-binding protein (CREB), and target of rapamycin kinase complex 1 (TORC1). Moreover, the expression status of genes associated with the control of glucose metabolism was measured in treated cells. The activation of cell signalling proteins was then evaluated in capsaicin- or zinc treated cells in the presence or absence of cell-permeant calcium chelator (BAPTA-AM) and the CAMKK inhibitor (STO-609). Finally, capsaicin- and zinc-induced glucose uptake was measured in the cells pre-treated with or without BAPTA-AM. Our results indicate that calcium flux induced by capsaicin or zinc led to activation of calcium signalling molecules and promoting glucose uptake in skeletal muscle cells. Pharmacological inhibition of CAMKK diminished activation of signalling molecules. Moreover, we observed an increase in intracellular cAMP levels in the cells after treatment with capsaicin and zinc. Our data show that capsaicin and zinc mediate glucose uptake in C2C12 skeletal muscle cells through the activation of calcium signalling.

SPOCK1 Promotes the Development of Hepatocellular Carcinoma

The extracellular matrix proteoglycan SPOCK1 is increasingly recognized as a contributor to the development and progression of cancers. Here, we study how SPOCK1, which is present in non-tumorous hepatocytes at low concentrations, promotes the development and progression of malignant hepatocellular tumors. Although SPOCK1 is an extracellular matrix proteoglycan, its concentration increases in the cytoplasm of hepatocytes starting with very low expression in the normal cells and then appearing in much higher quantities in cells of cirrhotic human liver and hepatocellular carcinoma. This observation is similar to that observed after diethylnitrosamine induction of mouse hepatocarcinogenesis. Furthermore, syndecan-1, the major proteoglycan of the liver, and SPOCK1 are in inverse correlation in the course of these events. In hepatoma cell lines, the cytoplasmic SPOCK1 colocalized with mitochondrial markers, such as MitoTracker and TOMM20, a characteristic protein of the outer membrane of the mitochondrion and could be detected in the cell nucleus. SPOCK1 downregulation of hepatoma cell lines by siRNA inhibited cell proliferation, upregulated p21 and p27, and interfered with pAkt and CDK4 expression. A tyrosine kinase array revealed that inhibition of SPOCK1 in the liver cancer cells altered MAPK signaling and downregulated several members of the Sarc family, all related to the aggressivity of the hepatoma cell lines. These studies support the idea that SPOCK1 enhancement in the liver is an active contributor to human and rodent hepatocarcinogenesis and cancer progression. However, its mitochondrial localization raises the possibility that it has a currently unidentified physiological function in normal hepatocytes.

Bee Venom Activates the Nrf2/HO-1 and TrkB/CREB/BDNF Pathways in Neuronal Cell Responses against Oxidative Stress Induced by Aβ1-42

Honeybee venom has recently been considered an anti-neurodegenerative agent, primarily due to its anti-inflammatory effects. The natural accumulation of amyloid-beta (Aβ) in the brain is reported to be the natural cause of aging neural ability downfall, and oxidative stress is the main route by which Aβ ignites its neural toxicity. Anti-neural oxidative stress is considered an effective approach for neurodegenerative therapy. To date, it is unclear how bee venom ameliorates neuronal cells in oxidative stress induced by Aβ. Here, we evaluated the neuroprotective effect of bee venom on Aβ-induced neural oxidative stress in both HT22 cells and an animal model. Our results indicate that bee venom protected HT22 cells against apoptosis induced by Aβ_1–42. This protective effect was explained by the increased nuclear translocation of nuclear factor erythroid 2-like 2 (Nrf2), consequently upregulating the production of heme oxygenase-1 (HO-1), a critical cellular instinct antioxidant enzyme that neutralizes excessive oxidative stress. Furthermore, bee venom treatment activated the tropomyosin-related kinase receptor B (TrkB)/cAMP response element-binding (CREB)/brain-derived neurotrophic factor (BDNF), which is closely related to the promotion of cellular antioxidant defense and neuronal functions. A mouse model with cognitive deficits induced by Aβ_1–42 intracerebroventricular (ICV) injections was also used. Bee venom enhanced animal cognitive ability and enhanced neural cell genesis in the hippocampal dentate gyrus region in a dose-dependent manner. Further analysis of animal brain tissue and serum confirmed that bee venom reduced oxidative stress, cholinergic system activity, and intercellular neurotrophic factor regulation, which were all adversely affected by Aβ_1–42. Our study demonstrates that bee venom exerts antioxidant and neuroprotective actions against neural oxidative stress caused by Aβ_1–42, thereby promoting its use as a therapeutic agent for neurodegenerative disorders.

Clinical Implication of Phosphodiesterase-4-Inhibition

The pleiotropic function of 3',5'-cyclic adenosine monophosphate (cAMP)-dependent pathways in health and disease led to the development of pharmacological phosphodiesterase inhibitors (PDE-I) to attenuate cAMP degradation. While there are many isotypes of PDE, a predominant role of PDE4 is to regulate fundamental functions, including endothelial and epithelial barrier stability, modulation of inflammatory responses and cognitive and/or mood functions. This makes the use of PDE4-I an interesting tool for various therapeutic approaches. However, due to the presence of PDE4 in many tissues, there is a significant danger for serious side effects. Based on this, the aim of this review is to provide a comprehensive overview of the approaches and effects of PDE4-I for different therapeutic applications. In summary, despite many obstacles to use of PDE4-I for different therapeutic approaches, the current data warrant future research to utilize the therapeutic potential of phosphodiesterase 4 inhibition.