Human lncRNA SUGCT-AS1 Regulates the Proinflammatory Response of Macrophage.

Macrophages are the major primary immune cells that mediate the inflammatory response. In this process, long non-coding RNAs (lncRNAs) play an important, yet largely unknown role. Therefore, utilizing several publicly available RNA sequencing datasets, we predicted and selected lncRNAs that are differentially expressed in M1 or M2 macrophages and involved in the inflammatory response. We identified SUGCT-AS1, which is a human macrophage-specific lncRNA whose expression is increased upon M1 macrophage stimulation. Conditioned media of SUGCT-AS1-depleted M1 macrophages induced an inflammatory phenotype of vascular smooth muscle cells, which included increased expression of inflammatory genes (IL1B and IL6), decreased contractile marker proteins (ACTA2 and SM22α), and increased cell migration. Depletion of SUGCT-AS1 promoted the expression and secretion of proinflammatory cytokines, such as TNF, IL1B, and IL6, in M1 macrophages, and transcriptomic analysis showed that SUGCT-AS1 has functions related to inflammatory responses and cytokines. Furthermore, we found that SUGCT-AS1 directly binds to hnRNPU and regulates its nuclear-cytoplasmic translocation. This translocation of hnRNPU altered the proportion of the MALT1 isoforms by regulating the alternative splicing of MALT1, a mediator of NF-κB signaling. Overall, our findings suggest that lncRNAs can be used for future studies on macrophage regulation. Moreover, they establish the SUGCT-AS1/hnRNPU/MALT1 axis, which is a novel inflammatory regulatory mechanism in macrophages.

Profiling and Cellular Analyses of Obesity-Related circRNAs in Neurons and Glia under Obesity-like In Vitro Conditions.

Recent evidence indicates that the pathogenesis of neurodegenerative diseases, including Alzheimer's disease, is associated with metabolic disorders such as diabetes and obesity. Various circular RNAs (circRNAs) have been found in brain tissues and recent studies have suggested that circRNAs are related to neuropathological mechanisms in the brain. However, there is a lack of interest in the involvement of circRNAs in metabolic imbalance-related neuropathological problems until now. Herein we profiled and analyzed diverse circRNAs in mouse brain cell lines (Neuro-2A neurons, BV-2 microglia, and C8-D1a astrocytes) exposed to obesity-related in vitro conditions (high glucose, high insulin, and high levels of tumor necrosis factor-alpha, interleukin 6, palmitic acid, linoleic acid, and cholesterol). We observed that various circRNAs were differentially expressed according to cell types with many of these circRNAs conserved in humans. After suppressing the expression of these circRNAs using siRNAs, we observed that these circRNAs regulate genes related to inflammatory responses, formation of synaptic vesicles, synaptic density, and fatty acid oxidation in neurons; scavenger receptors in microglia; and fatty acid signaling, inflammatory signaling cyto that may play important roles in metabolic disorders associated with neurodegenerative diseases.

A new paradigm in sarcopenia: Cognitive impairment caused by imbalanced myokine secretion and vascular dysfunction.

Sarcopenia characterized by reduced skeletal muscle mass and decreased muscle strength is increasing in prevalence globally. The pathophysiology of sarcopenia is related to various factors including hormonal imbalance, increased intracellular oxidative stress, reduction of food intake, advanced age, low body mass index, and low physical activity. Recently, sarcopenia has been reported to be associated with cognitive decline, and the common risk factors between sarcopenia and memory loss were observed in cohort studies. Many researchers suggested that the prevalence of sarcopenia is associated with vascular disorder, such as atherosclerosis and alteration of intracellular mechanisms caused by changes in myokine secretion. We herein review the emerging evidence on the strong link between cognitive impairment and sarcopenia, focusing on myokine secretion and vascular dysfunction, and provide an understanding of the relevant mechanisms and crucial determinants in cognitive decline caused by sarcopenia.

Circular RNA circSmoc1-2 regulates vascular calcification by acting as a miR-874-3p sponge in vascular smooth muscle cells.

Vascular calcification (VC), or calcium deposition inside the blood vessels, is common in patients with atherosclerosis, cardiovascular disease, and chronic kidney disease. Although several treatments are available to reduce calcification, the incidence of VC continues to rise. Recently, there have been several reports describing the regulation of circular RNAs (circRNAs) in various diseases. However, the role of circRNAs in VC has not yet been fully explored. Here, we investigated the function of circSmoc1-2, one of the circRNAs generated from the Smoc1 gene, which is downregulated in response to VC. CircSmoc1-2 is localized primarily to the cytoplasm and is resistant to exonuclease digestion. Inhibition of circSmoc1-2 worsens VC, while overexpression of circSmoc1-2 reduces VC, suggesting that circSmoc1-2 can prevent calcification. We went on to investigate the mechanism of circSmoc1-2 as a microRNA sponge and noted that miR-874-3p, the predicted target of circSmoc1-2, promotes VC, while overexpression of circSmoc1-2 reduces VC by suppressing miR-874-3p. Additionally, we identified the potential mRNA target of miR-874-3p as Adam19. In conclusion, we revealed that the circSmoc1-2/miR-874-3p/Adam19 axis regulates VC, suggesting that circSmoc1-2 may be a novel therapeutic target in the treatment of VC.

Obesity-linked circular RNA circTshz2-2 regulates the neuronal cell cycle and spatial memory in the brain.

Metabolic syndromes, including obesity, cause neuropathophysiological changes in the brain, resulting in cognitive deficits. Only a few studies explored the contribution of non-coding genes in these pathophysiologies. Recently, we identified obesity-linked circular RNAs (circRNA) by analyzing the brain cortices of high-fat-fed obese mice. In this study, we scrutinized a conserved and neuron-specific circRNA, circTshz2-2, which affects neuronal cell cycle and spatial memory in the brain. Transcriptomic and cellular analysis indicated that circTshz2-2 dysregulation altered the expression of cell division-related genes and induced cell cycle arrest at the G2/M phase of the neuron. We found that circTshz2-2 bound to the YY1 transcriptional complex and suppressed Bdnf transcription. Suppression of circTshz2-2 increased BDNF expression and reduced G2/M checkpoint proteins such as Cyclin B2 and CDK1 through BDNF/TrkB signaling pathway, resulting in cell cycle arrest and neurite elongation. Inversely, overexpression of circTshz2-2 decreased BDNF expression, induced cell cycle proteins, and shortened the neurite length, indicating that circTshz2-2 regulates neuronal cell cycle and structure. Finally, we showed that circTshz2-2 affects spatial memory in wild-type and obese mice. Our data have revealed potential regulatory roles of obesity-related circTshz2-2 on the neuronal cell cycle and memory function providing a novel link between metabolic syndromes and cognitive deficits.

Exendin-4 improves long-term potentiation and neuronal dendritic growth in vivo and in vitro obesity condition.

Metabolic syndrome, which increases the risk of obesity and type 2 diabetes has emerged as a significant issue worldwide. Recent studies have highlighted the relationship between metabolic imbalance and neurological pathologies such as memory loss. Glucagon-like peptide 1 (GLP-1) secreted from gut L-cells and specific brain nuclei plays multiple roles including regulation of insulin sensitivity, inflammation and synaptic plasticity. Although GLP-1 and GLP-1 receptor agonists appear to have neuroprotective function, the specific mechanism of their action in brain remains unclear. We investigated whether exendin-4, as a GLP-1RA, improves cognitive function and brain insulin resistance in metabolic-imbalanced mice fed a high-fat diet. Considering the result of electrophysiological experiments, exendin-4 inhibits the reduction of long term potentiation (LTP) in high fat diet mouse brain. Further, we identified the neuroprotective effect of exendin-4 in primary cultured hippocampal and cortical neurons in in vitro metabolic imbalanced condition. Our results showed the improvement of IRS-1 phosphorylation, neuronal complexity, and the mature of dendritic spine shape by exendin-4 treatment in metabolic imbalanced in vitro condition. Here, we provides significant evidences on the effect of exendin-4 on synaptic plasticity, long-term potentiation, and neural structure. We suggest that GLP-1 is important to treat neuropathology caused by metabolic syndrome.

Role of Exendin-4 in Brain Insulin Resistance, Mitochondrial Function, and Neurite Outgrowth in Neurons under Palmitic Acid-Induced Oxidative Stress.

Glucagon like peptide 1 (GLP-1) is an incretin hormone produced by the gut and brain, and is currently being used as a therapeutic drug for type 2 diabetes and obesity, suggesting that it regulates abnormal appetite patterns, and ameliorates impaired glucose metabolism. Many researchers have demonstrated that GLP-1 agonists and GLP-1 receptor agonists exert neuroprotective effects against brain damage. Palmitic acid (PA) is a saturated fatty acid, and increases the risk of neuroinflammation, lipotoxicity, impaired glucose metabolism, and cognitive decline. In this study, we investigated whether or not Exentin-4 (Ex-4; GLP-1 agonist) inhibits higher production of reactive oxygen species (ROS) in an SH-SY5Y neuronal cell line under PA-induced apoptosis conditions. Moreover, pre-treatment with Ex-4 in SH-SY5Y neuronal cells prevents neural apoptosis and mitochondrial dysfunction through several cellular signal pathways. In addition, insulin sensitivity in neurons is improved by Ex-4 treatment under PA-induced insulin resistance. Additionally, our imaging data showed that neuronal morphology is improved by EX-4 treatment, in spite of PA-induced neuronal damage. Furthermore, we identified that Ex-4 inhibits neuronal damage and enhanced neural complexity, such as neurite length, secondary branches, and number of neurites from soma in PA-treated SH-SY5Y. We observed that Ex-4 significantly increases neural complexity, dendritic spine morphogenesis, and development in PA treated primary cortical neurons. Hence, we suggest that GLP-1 administration may be a crucial therapeutic solution for improving neuropathology in the obese brain.

Role of Adiponectin and Brain Derived Neurotrophic Factor in Metabolic Regulation Involved in Adiposity and Body Fat Browning.

Obesity, characterized by excessive fat mass, has been emerging as a major global epidemic and contributes to the increased risk of morbidity around the world. Thus, the necessity to find effective therapy and specific regulatory mechanisms is increasing for controlling obesity. Lately, many researchers have been interested in the linkage between obesity and adipokines/myokines, particularly adiponectin and brain-derived neurotrophic factor (BDNF). However, the role of adiponectin and BDNF in adiposity has not been clearly defined yet. We examined the association of adiposity with adiponectin and BDNF through human study (observational study) with Korean women and in vitro experiments. In the human study, we found a negative relationship between adiposity and circulating adiponectins but irregular patterns in the relationship between adiposity and circulating BDNFs. In the in vitro study using 3T3-L1 adipocytes, adiponectin treatment strongly promoted adipocyte differentiation and the fat browning process, whereas BDNF treatment attenuated adipocyte differentiation and the fat browning process in differentiated adipocytes. Our results demonstrate that adiponectin and BDNF play an important role in regulating fat mass and the expression of fat-browning markers in different ways, and also suggest that circulating adiponectin may be used as an important monitoring index for obesity status.

Glucagon-like peptide-1 suppresses neuroinflammation and improves neural structure.

Glucagon-like peptide-1 (GLP-1) is a hormone mainly secreted from enteroendocrine L cells. GLP-1 and its receptor are also expressed in the brain. GLP-1 signaling has pivotal roles in regulating neuroinflammation and memory function, but it is unclear how GLP-1 improves memory function by regulating neuroinflammation. Here, we demonstrated that GLP-1 enhances neural structure by inhibiting lipopolysaccharide (LPS)-induced inflammation in microglia with the effects of GLP-1 itself on neurons. Inflammatory secretions of BV-2 microglia by LPS aggravated mitochondrial function and cell survival, as well as neural structure in Neuro-2a neurons. In inflammatory condition, GLP-1 suppressed the secretion of tumor necrosis factor-alpha (TNF-α)-associated cytokines and chemokines in BV-2 microglia and ultimately enhanced neurite complexity (neurite length, number of neurites from soma, and secondary branches) in Neuro-2a neurons. We confirmed that GLP-1 improves neurite complexity, dendritic spine morphogenesis, and spine development in TNF-α-treated primary cortical neurons based on altered expression levels of the factors related to neurite growth and spine morphology. Given that our data that GLP-1 itself enhances neurite complexity and spine morphology in neurons, we suggest that GLP-1 has a therapeutic potential in central nervous system diseases.

Transcriptomic Analysis of High Fat Diet Fed Mouse Brain Cortex.

High fat diet can lead to metabolic diseases such as obesity and diabetes known to be chronic inflammatory diseases with high prevalence worldwide. Recent studies have reported cognitive dysfunction in obese patients is caused by a high fat diet. Accordingly, such dysfunction is called "type 3 diabetes" or "diabetic dementia." Although dysregulation of protein-coding genes has been extensively studied, profiling of non-coding RNAs including long non-coding RNAs (lncRNAs) and circular RNAs (circRNAs) has not been reported yet. Therefore, the objective of this study was to obtain profiles of diverse RNAs and determine their patterns of alteration in high fat fed brain cortex compared to normal brain cortex. To investigate regulatory roles of both coding and non-coding RNAs in high fat diet brain, we performed RNA sequencing of ribosomal RNA-depleted RNAs and identified genome-wide lncRNAs and circRNAs expression and co-expression patterns of mRNAs in high fat diet mouse brain cortex. Our results showed expression levels of mRNAs related to neurogenesis, synapse, and calcium signaling were highly changed in high fat diet fed cortex. In addition, numerous differentially expressed lncRNAs and circRNAs were identified. Our study provides valuable expression profiles and potential function of both coding and non-coding RNAs in high fat diet fed brain cortex.

Transcriptome Analysis of Pineal Glands in the Mouse Model of Alzheimer's Disease.

The pineal gland maintains the circadian rhythm in the body by secreting the hormone melatonin. Alzheimer's disease (AD) is the most common neurodegenerative disease. Pineal gland impairment in AD is widely observed, but no study to date has analyzed the transcriptome in the pineal glands of AD. To establish resources for the study on pineal gland dysfunction in AD, we performed a transcriptome analysis of the pineal glands of AD model mice and compared them to those of wild type mice. We identified the global change of diverse protein-coding RNAs, which are implicated in the alteration in cellular transport, protein transport, protein folding, collagen expression, histone dosage, and the electron transfer system. We also discovered various dysregulated long noncoding RNAs and circular RNAs in the pineal glands of mice with AD. This study showed that the expression of diverse RNAs with important functional implications in AD was changed in the pineal gland of the AD mouse model. The analyzed data reported in this study will be an important resource for future studies to elucidate the altered physiology of the pineal gland in AD.

Intermittent Fasting: a Promising Approach for Preventing Vascular Dementia.

Vascular dementia is the most common neuropsychiatric syndrome and is characterized by synaptic dysfunction, neuroinflammation, and cognitive dysfunction. Vascular dementia is associated with various environmental, genetic, and lifestyle risk factors. Recent research has focused on the association between vascular dementia and dietary patterns, suggesting that dietary regulation leads to better control of energy metabolism, improvements in brain insulin resistance, and the suppression of neuroinflammation. Intermittent fasting is a calorie-restriction method known to be more effective in promoting fat loss and regulating the impairment of glucose metabolism as compared with other dietary restriction regimens. Herein, the authors review the effects of intermittent fasting with regard to vascular dementia based on recent evidence and propose that intermittent fasting could be a therapeutic approach for ameliorating vascular dementia pathology and preventing its onset.

The small molecule CA140 inhibits the neuroinflammatory response in wild-type mice and a mouse model of AD.

BACKGROUND: Neuroinflammation is associated with neurodegenerative diseases, including Alzheimer's disease (AD). Thus, modulating the neuroinflammatory response represents a potential therapeutic strategy for treating neurodegenerative diseases. Several recent studies have shown that dopamine (DA) and its receptors are expressed in immune cells and are involved in the neuroinflammatory response. Thus, we recently developed and synthesized a non-self-polymerizing analog of DA (CA140) and examined the effect of CA140 on neuroinflammation. METHODS: To determine the effects of CA140 on the neuroinflammatory response, BV2 microglial cells were pretreated with lipopolysaccharide (LPS, 1 µg/mL), followed by treatment with CA140 (10 µM) and analysis by reverse transcription-polymerase chain reaction (RT-PCR). To examine whether CA140 alters the neuroinflammatory response in vivo, wild-type mice were injected with both LPS (10 mg/kg, intraperitoneally (i.p.)) and CA140 (30 mg/kg, i.p.), and immunohistochemistry was performed. In addition, familial AD (5xFAD) mice were injected with CA140 or vehicle daily for 2 weeks and examined for microglial and astrocyte activation. RESULTS: Pre- or post-treatment with CA140 differentially regulated proinflammatory responses in LPS-stimulated microglia and astrocytes. Interestingly, CA140 regulated D1R levels to alter LPS-induced proinflammatory responses. CA140 significantly downregulated LPS-induced phosphorylation of ERK and STAT3 in BV2 microglia cells. In addition, CA140-injected wild-type mice exhibited significantly decreased LPS-induced microglial and astrocyte activation. Moreover, CA140-injected 5xFAD mice exhibited significantly reduced microglial and astrocyte activation. CONCLUSIONS: CA140 may be beneficial for preventing and treating neuroinflammatory-related diseases, including AD.

Ibrutinib suppresses LPS-induced neuroinflammatory responses in BV2 microglial cells and wild-type mice.

BACKGROUND: The FDA-approved small-molecule drug ibrutinib is an effective targeted therapy for patients with chronic lymphocytic leukemia (CLL). Ibrutinib inhibits Bruton's tyrosine kinase (BTK), a kinase involved in B cell receptor signaling. However, the potential regulation of neuroinflammatory responses in the brain by ibrutinib has not been comprehensively examined. METHODS: BV2 microglial cells were treated with ibrutinib (1 µM) or vehicle (1% DMSO), followed by lipopolysaccharide (LPS; 1 µg/ml) or PBS. RT-PCR, immunocytochemistry, and subcellular fractionation were performed to examine the effects of ibrutinib on neuroinflammatory responses. In addition, wild-type mice were sequentially injected with ibrutinib (10 mg/kg, i.p.) or vehicle (10% DMSO, i.p.), followed by LPS (10 mg/kg, i.p.) or PBS, and microglial and astrocyte activations were assessed using immunohistochemistry. RESULTS: Ibrutinib significantly reduced LPS-induced increases in proinflammatory cytokine levels in BV2 microglial and primary microglial cells but not in primary astrocytes. Ibrutinib regulated TLR4 signaling to alter LPS-induced proinflammatory cytokine levels. In addition, ibrutinib significantly decreased LPS-induced increases in p-AKT and p-STAT3 levels, suggesting that ibrutinib attenuates LPS-induced neuroinflammatory responses by inhibiting AKT/STAT3 signaling pathways. Interestingly, ibrutinib also reduced LPS-induced BV2 microglial cell migration by inhibiting AKT signaling. Moreover, ibrutinib-injected wild-type mice exhibited significantly reduced microglial/astrocyte activation and COX-2 and IL-1ß proinflammatory cytokine levels. CONCLUSIONS: Our data provide insights on the mechanisms of a potential therapeutic strategy for neuroinflammation-related diseases.

The Adiponectin Homolog Osmotin Enhances Neurite Outgrowth and Synaptic Complexity via AdipoR1/NgR1 Signaling in Alzheimer's Disease.

Alzheimer's disease is a major neurodegenerative disease characterized by memory loss and cognitive deficits. Recently, we reported that osmotin, which is a homolog of adiponectin, improved long-term potentiation and cognitive functions in Alzheimer's disease mice. Several lines of evidence have suggested that Nogo-A and the Nogo-66 receptor 1 (NgR1), which form a complex that inhibits long-term potentiation and cognitive function, might be associated with the adiponectin receptor 1 (AdipoR1), which is a receptor for osmotin. Here, we explore whether osmotin's effects on long-term potentiation and memory function are associated with NgR1 signaling via AdipoR1 in Alzheimer's disease. Osmotin reduced the expression of NgR1 without affecting Nogo-A expression. Furthermore, osmotin inhibited NgR1 signaling by prohibiting the formation of the Nogo-A and NgR1 ligand-receptor complex, resulting in enhanced neurite outgrowth; these effects disappeared in the presence of AdipoR1 interference. In addition, osmotin increased the expression of the pre- and postsynaptic markers synaptophysin and PSD-95, as well as the activation of the memory-associated markers AMPA receptor and CREB; these effects occurred in an AdipoR1- and NgR1-dependent manner. Osmotin was also found to enhance dendritic complexity and spine density in the hippocampal region of Alzheimer's disease mouse brains. These results suggest that osmotin can enhance neurite outgrowth and synaptic complexity through AdipoR1 and NgR1 signaling, implying that osmotin might be an effective therapeutic agent for Alzheimer's disease and that AdipoR1 might be a crucial therapeutic target for neurodegenerative diseases such as Alzheimer's.

Inhibition of c-Jun N-Terminal Kinase Protects Against Brain Damage and Improves Learning and Memory After Traumatic Brain Injury in Adult Mice.

Traumatic brain injury (TBI) is a global risk factor that leads to long-term cognitive impairments. To date, the disease remains without effective therapeutics because of the multifactorial nature of the disease. Here, we demonstrated that activation of the c-Jun N-terminal kinase (JNK) is involved in multiple pathological features of TBI. Therefore, we investigated the disease-modifying therapeutic potential of JNK-specific inhibitor (SP600125) in TBI mice. Treating 2 different models of TBI mice with SP600125 for 7 days dramatically inhibited activated JNK, resulting in marked reductions of amyloid precursor protein (APP) expression level and in amyloid beta production and hyperphosphorylated tau and regulation of the abnormal expression of secretases. Furthermore, SP600125 strongly inhibited inflammatory responses, blood-brain barrier breakdown, apoptotic neurodegeneration, and synaptic protein loss, regulated prosurvival processes and improved motor function and behavioral outcomes in TBI mice. More interestingly, we found that SP600125 treatment ameliorated amyloidogenic APP processing and promoted the nonamyloidogenic pathway in TBI mouse brains. Our findings strongly suggest that active JNK is critically involved in disease development after TBI and that inhibition of JNK with SP600125 is highly efficient for slowing disease progression by reducing multiple pathological features in TBI mouse brains and regulating cognitive dysfunction.

Molecular Cloning and Expression of Osmotin in a Baculovirus-Insect System: Purified Osmotin Mitigates Amyloid-beta Deposition in Neuronal Cells.

Osmotin is a pathogenesis-related plant protein, have gained focus of research because of its homology with mammalian adiponectin. The therapeutic properties of osmotin have been explored in recent years as it exhibits neuroprotective effects against amyloid beta-, glutamate- and ethanol-induced synaptic dysfunction and neurodegeneration. In the present study, the full-length gene of the tobacco plant osmotin was cloned and expressed in the Sf9 insect cell line using the baculovirus expression system. In vitro analysis of purified Osmotin protein showed excellent cell viability, p-AMPK activation and a reduction in amyloid-beta deposition. Immunofluorescent analysis showed significant reduction in amyloid beta deposition in APP over expressing neuronal cells. Osmotin inhibited amyloid beta deposition by influencing expression of APP processing genes including APP, ADAM 10 and BACE 1. Purified Osmotin showed reduction in amyloid beta deposition in different in vitro models as well. Osmotin showed similar mechanism when compared with mammalian adiponectin in different in vitro models. The present method will be an excellent approach for the efficient and cost-effective production of the functional protein to be utilized for therapeutic purposes. Reduction in amyloid beta deposition by activation of p-AMPK influencing APP processing genes makes osmotin a potent therapeutic candidate for neurodegenerative diseases.