Publications by authors named "Sang-Ha Baik"

Intermittent fasting (IF) has been shown to reduce cardiovascular risk factors in both animals and humans, and can protect the heart against ischemic injury in models of myocardial infarction. However, the underlying molecular mechanisms behind these effects remain unclear. To shed light on the molecular and cellular adaptations of the heart to IF, we conducted comprehensive system-wide analyses of the proteome, phosphoproteome, and transcriptome, followed by functional analysis.

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Vascular dementia (VaD) is a progressive cognitive impairment of vascular etiology. VaD is characterized by cerebral hypoperfusion, increased blood-brain barrier permeability and white matter lesions. An increased burden of VaD is expected in rapidly aging populations.

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We recently discovered that Mfsd2b, which is the S1P exporter found in blood cells. Here, we report that Mfsd2b is critical for the release of all S1P species in both resting and activated platelets. We show that resting platelets store S1P in the cytoplasm.

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Introduction: Intermittent fasting (IF) has been suggested to have neuroprotective effects through the activation of multiple signaling pathways. Rodents fasted intermittently exhibit enhanced hippocampal neurogenesis and long-term potentiation (LTP) at hippocampal synapses compared with sedentary animals fed an ad libitum (AL) diet. However, the underlying mechanisms have not been studied.

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Intermittent fasting (IF) has been extensively reported to promote improved energy homeostasis and metabolic switching. While IF may be a plausible strategy to ameliorate the epidemiological burden of disease in many societies, our understanding of the underlying molecular mechanisms behind such effects is still lacking. The present study has sought to investigate the relationship between IF and changes in gene expression.

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BACE1 is the rate-limiting enzyme for amyloid-β peptides (Aβ) generation, a key event in the pathogenesis of Alzheimer's disease (AD). By an unknown mechanism, levels of and a mRNA-stabilizing antisense RNA () are elevated in the brains of AD patients, implicating that dysregulation of expression plays an important role in AD pathogenesis. We found that nuclear factor erythroid-derived 2-related factor 2 (NRF2/NFE2L2) represses the expression of and through binding to antioxidant response elements (AREs) in their promoters of mouse and human.

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Inhibition of Notch signalling has shown anti-inflammatory properties and models of rheumatoid arthritis (RA). The objective of this study was to determine whether Notch1 might play a role in regulating T-regulatory cells (Tregs) in animal models of RA. Collagen-induced arthritis (CIA) and collagen antibody-induced arthritis (CAIA) were induced in C57BL/6, Notch1 antisense transgenic (NAS) or DBA1/J mice.

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Stroke is the second leading cause of death in the world and a major cause of long-term disability. Recent evidence has provided insight into a newly described inflammatory mechanism that contributes to neuronal and glial cell death, and impaired neurological outcome following ischemic stroke - a form of sterile inflammation involving innate immune complexes termed inflammasomes. It has been established that inflammasome activation following ischemic stroke contributes to neuronal cell death, but little is known about inflammasome function and cell death in activated microglial cells following cerebral ischemia.

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Sirtuin 2 (SIRT2) is a family member of nicotinamide adenine dinucleotide (NAD)-dependent deacetylases which appears to have detrimental roles in an array of neurological disorders such as Parkinson's disease (PD) and Huntington's disease (HD). In light of the recently emerging roles of sirtuins in normal physiology and pathological conditions such as ischemic stroke, we investigated the role of SIRT2 in ischemic stroke-induced neuronal cell death. Primary cortical neurons were subjected to oxygen-glucose deprivation (OGD) under in vitro ischemic conditions, and subsequently tested for the efficacy of SIRT2 inhibitors AK1 and AGK2 in attenuating apoptotic cell death caused by OGD.

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Ischemic stroke is a leading cause of morbidity and death, with the outcome largely determined by the amount of hypoxia-related neuronal death in the affected brain regions. Cerebral ischemia and hypoxia activate the Notch1 signaling pathway and four prominent interacting pathways (NF-κB, p53, HIF-1α and Pin1) that converge on a conserved DNA-associated nuclear multi-protein complex, which controls the expression of genes that can determine the fate of neurons. When neurons experience a moderate level of ischemic insult, the nuclear multi-protein complex up-regulates adaptive stress response genes encoding proteins that promote neuronal survival, but when ischemia is more severe the nuclear multi-protein complex induces genes encoding proteins that trigger and execute a neuronal death program.

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Genetic changes due to dietary intervention in the form of either calorie restriction (CR) or intermittent fasting (IF) are not reported in detail until now. However, it is well established that both CR and IF extend the lifespan and protect against neurodegenerative diseases and stroke. The current research aims were first to describe the transcriptomic changes in brains of IF mice and, second, to determine whether IF induces extensive transcriptomic changes following ischemic stroke to protect the brain from injury.

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Stroke is the world's second leading cause of mortality, with a high incidence of morbidity. Numerous neuronal membrane receptors are activated by endogenous ligands and may contribute to infarct development. Notch is a well-characterized membrane receptor involved in cell differentiation and proliferation, and now shown to play a pivotal role in cell death during ischemic stroke.

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Excessive mitochondrial fission is a prominent early event and contributes to mitochondrial dysfunction, synaptic failure, and neuronal cell death in the progression of Alzheimer's disease (AD). However, it remains to be determined whether inhibition of excessive mitochondrial fission is beneficial in mammal models of AD. To determine whether dynamin-related protein 1 (Drp1), a key regulator of mitochondrial fragmentation, can be a disease-modifying therapeutic target for AD, we examined the effects of Drp1 inhibitor on mitochondrial and synaptic dysfunctions induced by oligomeric amyloid-β (Aβ) in neurons and neuropathology and cognitive functions in Aβ precursor protein/presenilin 1 double-transgenic AD mice.

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Article Synopsis
  • Multi-protein complexes called inflammasomes, particularly NLRP1 and NLRP3, contribute to neuronal cell death and brain injury following ischemic strokes.
  • The study finds that the NF-κB and MAPK signaling pathways are responsible for the expression and activation of these inflammasome proteins, and that using specific inhibitors can reduce their effects in brain tissue.
  • Additionally, intravenous immunoglobulin (IVIg) treatment can decrease the activation of the NF-κB and MAPK pathways, lowering NLRP1 and NLRP3 expression while increasing protective proteins, suggesting potential new therapeutic approaches for ischemic stroke.
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Notch signaling pathways modulate various cellular processes, including cell proliferation, differentiation, adhesion, and communication. Recent studies have demonstrated that Notch1 signaling also regulates hepatic glucose production and lipid synthesis. However, the effect of Notch1 signaling on hepatic lipid oxidation has not yet been directly investigated.

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Article Synopsis
  • Stroke is a major health issue causing high rates of death and disability, and recent research highlights the role of Pin1, an enzyme that affects cell growth and apoptosis, in this context.
  • In laboratory studies and mouse models, manipulating Pin1 levels showed that it enhances the stability of Notch1 intracellular domain (NICD1), leading to increased neuron death during ischemic conditions, while reducing Pin1 levels offered protection against stroke damage.
  • The findings suggest that targeting Pin1 could be a potential new treatment strategy for ischemic stroke by inhibiting its role in promoting harmful cell signaling related to stroke-related neuron death.
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Objective: To test the hypothesis that Notch signalling plays a role in the pathogenesis of rheumatoid arthritis (RA) and to determine whether pharmacological inhibition of Notch signalling with γ-secretase inhibitors can ameliorate the RA disease process in an animal model.

Methods: Collagen-induced arthritis was induced in C57BL/6 or Notch antisense transgenic mice by immunisation with chicken type II collagen (CII). C57BL/6 mice were administered with different doses of inhibitors of γ-secretase, an enzyme required for Notch activation, at disease onset or after onset of symptoms.

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Toll-like receptors (TLRs) are transmembrane pattern-recognition receptors that initiate signals in response to diverse pathogen-associated molecular patterns. Several groups have recently reported a role for TLR2 and TLR4 in ischemic stroke-induced brain injury. However, relatively little is known about the role of TLR8 in ischemic stroke.

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Recent findings suggest that Notch-1 signaling contributes to neuronal death in ischemic stroke, but the underlying mechanisms are unknown. Hypoxia inducible factor-1α (HIF-1α), a global regulator of cellular responses to hypoxia, can interact with Notch and modulate its signaling during hypoxic stress. Here we show that Notch signaling interacts with the HIF-1α pathway in the process of ischemic neuronal death.

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Calsenilin is a calcium sensor protein that interacts with presenilin and increases calcium-triggered neuronal apoptosis, and γ-secretase activity. Notch is a cell surface receptor that regulates cell-fate decisions and synaptic plasticity in brain. The aim of the present study was to characterize the role of calsenilin as a regulator of the γ-secretase cleavage of Notch in ischemic stroke.

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The cause of elevated level of amyloid β-peptide (Aβ42) in common late-onset sporadic [Alzheimer's disease (AD)] has not been established. Here, we show that the membrane lipid peroxidation product 4-hydroxynonenal (HNE) is associated with amyloid and neurodegenerative pathologies in AD and that it enhances γ-secretase activity and Aβ42 production in neurons. The γ-secretase substrate receptor, nicastrin, was found to be modified by HNE in cultured neurons and in brain specimens from patients with AD, in which HNE-nicastrin levels were found to be correlated with increased γ-secretase activity and Aβ plaque burden.

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Chronic alcohol consumption contributes to numerous diseases, including cancers, cardiovascular diseases, and liver cirrhosis. Epidemiological studies have shown that excessive alcohol consumption is a risk factor for dementia. Along this line, Alzheimer's disease (AD) is the most common form of dementia and is caused by the accumulation of amyloid-β (Aβ plaques in neurons.

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Accumulation of amyloid-β (Aβ) is widely accepted as the key instigator of Alzheimer's disease (AD). The proposed mechanism is that accumulation of Aβ results in inflammatory responses, oxidative damages, neurofibrillary tangles and, subsequently, neuronal/synaptic dysfunction and neuronal loss. Given the critical role of Aβ in the disease process, the proteases that produce this peptide are obvious targets.

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Article Synopsis
  • Presenilins are vital components of the gamma-secretase complex, which processes the beta-amyloid precursor protein (APP) into beta-amyloid, linked to Alzheimer's disease.
  • Mutations in presenilin lead to early-onset familial Alzheimer's, disrupting calcium (Ca(2+)) signaling and increasing cell death susceptibility.
  • The study shows that heightened gamma-secretase activity correlates with cell death from increased Ca(2+), and using specific inhibitors significantly reduces this type of cell death, highlighting gamma-secretase's role in the process.
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