Dong-Gyu Jo

Microglial neuroinflammation appears to be neuroprotective in the early pathological stage, yet neurotoxic, which often precedes neurodegeneration in Alzheimer's disease (AD). However, it remains unclear how the microglial activities transit to the neurotoxic state during AD progression, due to complex neuron‐glia interactions. Here, the mechanism of detrimental microgliosis in AD by employing 3D human AD mini‐brains, brain tissues of AD patients, and 5XFAD mice is explored. In the human and animal AD models, amyloid‐beta (Aβ)‐overexpressing neurons and reactive astrocytes produce interferon‐gamma (IFNγ) and excessive oxidative stress. IFNγ results in the downregulation of mitogen‐activated protein kinase (MAPK) and the upregulation of Kelch‐like ECH‐associated Protein 1 (Keap1) in microglia, which inactivate nuclear factor erythroid‐2‐related factor 2 (Nrf2) and sensitize microglia to the …

Extracellular vesicles (EVs), through their complex cargo, can reflect the state of their cell of origin and change the functions and phenotypes of other cells. These features indicate strong biomarker and therapeutic potential and have generated broad interest, as evidenced by the steady year‐on‐year increase in the numbers of scientific publications about EVs. Important advances have been made in EV metrology and in understanding and applying EV biology. However, hurdles remain to realising the potential of EVs in domains ranging from basic biology to clinical applications due to challenges in EV nomenclature, separation from non‐vesicular extracellular particles, characterisation and functional studies. To address the challenges and opportunities in this rapidly evolving field, the International Society for Extracellular Vesicles (ISEV) updates its ‘Minimal Information for Studies of Extracellular Vesicles’, which …

Ocular diseases are a growing global concern and have a significant impact on the quality of life. Cataracts, glaucoma, age-related macular degeneration, and diabetic retinopathy are the most prevalent ocular diseases. Their prevalence and the global market size are also increasing. However, the available pharmacotherapy is currently limited. These diseases share common pathophysiological features, including neovascularization, inflammation, and/or neurodegeneration. Histone deacetylases (HDACs) are a class of enzymes that catalyze the removal of acetyl groups from lysine residues of histone and nonhistone proteins. HDACs are crucial for regulating various cellular processes, such as gene expression, protein stability, localization, and function. They have also been studied in various research fields, including cancer, inflammatory diseases, neurological disorders, and vascular diseases. Our study aimed …

A bioactive compound, collagen peptide (CP), is widely used for biological activities such as anti-photoaging and antioxidant effects, with increased oral bioavailability because of its low molecular weight and high hydrophilicity. However, controlling release time and increasing retention time in the digestive tract for a more convenient oral administration is still a challenge. We developed CP-loaded chitosan (CS) microcapsules via strong and rapid ionic gelation using a highly negative phytic acid (PA) crosslinker. The platform enhanced the oral bioavailability of CP with controlled gastrointestinal delivery by utilizing the mucoadhesiveness and tight junction-opening properties of CS. CS and CP concentrations varied from 1.5 to 3.5% and 0–30%, respectively, for optimal and stable microcapsule synthesis. The physicochemical properties, in vitro release profile with intestinal permeability, in vivo oral bioavailability, in …

Background Accumulation of Aβ in a brain is one of the pathological hallmarks of Alzheimer’s disease (AD). Aβ is generated through sequential cleavage of amyloid precursor protein (APP) by β‐secretase (BACE1) and γ‐secretase complex. BACE1 is one of the crucial targets for AD given that BACE1 expression is significantly upregulated in AD patients compared with non‐AD. However, direct and complete inhibition of BACE1 activity can cause unpredictable or unintended effects because of numerous physiological substrates of BACE1. Method We screened small compounds, including drugs approved by the U.S. Food and Drug Administration to identify medicines that reduce promoter activity of BACE1. TG reduced the levels of BACE1 protein and mRNA in APP‐SH‐SY5Y cells. In order to confirm the effect of TG regulating the expression BACE1, we constructed the RFP (BACE1 expression indicator) ‐GFP …

Many approaches to neurodegenerative diseases that focus on amyloid-β clearance and gene therapy have not been successful. Some therapeutic applications focus on enhancing neuronal cell survival during the pathogenesis of neurodegenerative diseases, including mitochondrial dysfunction. Plasma membrane (PM) redox enzymes are crucial in maintaining cellular physiology and redox homeostasis in response to mitochondrial dysfunction. Neurohormetic phytochemicals are known to induce the expression of detoxifying enzymes under stress conditions. In this study, mechanisms of neuroprotective effects of 4-hydroxycinnamic acid (HCA) were examined by analyzing cell survival, levels of abnormal proteins, and mitochondrial functions in two different neuronal cells. HCA protected two neuronal cells exhibited high expression of PM redox enzymes and the consequent increase in the NAD+/NADH ratio …

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

Vascular cognitive impairment (VCI) describes a wide spectrum of cognitive deficits related to cerebrovascular diseases. Although the loss of blood flow to cortical regions critically involved in cognitive processes must feature as the main driver of VCI, the underlying mechanisms and interactions with related disease processes remain to be fully elucidated. Recent clinical studies of cerebral blood flow measurements have supported the role of chronic cerebral hypoperfusion (CCH) as a major driver of the vascular pathology and clinical manifestations of VCI. Here we review the pathophysiological mechanisms as well as neuropathological changes of CCH. Potential interventional strategies for VCI are also reviewed. A deeper understanding of how CCH can lead to accumulation of VCI-associated pathology could potentially pave the way for early detection and development of disease-modifying therapies, thus …

BackgroundSeveral epidemiological research have recommended a potential link between Helicobacter pylori infection and neurodegeneration, including Alzheimer’s and Parkinson’s diseases. However, the current research could not fully provide a comprehensive understanding of this association due to the absence of suitable model systems for studying multi-organ interactions and multiplex effects upon Helicobacter pylori infection.ResultsHere, we recapitulated a human stomach-brain axis by treating human in vitro cellular models with Helicobacter pylori’s cell-free supernatant (HP CFS). We first confirmed that HP CFS disrupted the tightness of gut and brain barriers via Vacuolating cytotoxin A (VacA) binding to Low-density Lipoprotein receptor 1 (LRP1) receptor, leading to reduced tight junction proteins and transmembrane electrical resistance. Blood-brain barrier-penetrating VacA toxin in HP CFS activated central innate immune cells, evidenced by the increased expression of inflammatory markers, oxidative stress, the release of neurotoxic factors, and inflammatory soluble markers, such as NO, IL-8, IL-18 from microglia as well as H 2 O 2, IL-6, and IL-16 from astrocytes. VacA toxin hindered microglial amyloid-beta phagocytosis of amyloid-beta by microglia through by blocking LRP1, a receptor for amyloid-beta. We found that VacA in HP CFS led to neurodegeneration, evidenced by the presence of phosphorylated tau, phosphorylated alpha-synuclein, synaptic impairment, and neuronal loss. Notably, microglia stimulated with VacA exacerbated neurodegeneration compared to direct HP CFS stimulation. Furthermore, we demonstrated …

Chronic cerebral hypoperfusion (CCH) is postulated to underlie multiple pathophysiological processes in vascular dementia (VaD), including extracellular matrix dysfunction. While several extracellular matrix proteins, namely cyclophilin A (CypA), extracellular matrix metalloproteinase inducer (EMMPRIN) and gelatinases (matrix metalloproteinases, MMP-2 and -9) have been investigated in acute stroke, their involvement in CCH and VaD remains unclear. In this study, CypA-EMMPRIN-gelatinase proteins were analysed in a clinical cohort of 36 aged, cognitively unimpaired subjects and 48 VaD patients, as well as in a bilateral carotid artery stenosis mouse model of CCH. Lower CypA and higher EMMPRIN levels were found in both VaD serum and CCH mouse brain. Furthermore, gelatinases were differentially altered in CCH mice and VaD patients, with significant MMP-2 increase in CCH brain and serum, whilst …

The present invention relates to a pharmaceutical composition for preventing or treating dentin-dental pulp disease or periodontal disease, a quasi-drug composition for preventing or improving dentin-dental pulp disease or periodontal disease or a health functional food composition for preventing or improving dentin-dental pulp disease or periodontal disease, all of which comprise a LPAR2 (lysophosphatidic acid receptor 2) inhibitor.

Spatial learning and memory flexibility are known to require long-term potentiation (LTP) and long-term depression (LTD), respectively, on a cellular basis. We previously showed that cyclin Y (CCNY), a synapse-remodeling cyclin, is a novel actin-binding protein and an inhibitory regulator of functional and structural LTP in vitro. In this study, we report that Ccny knockout (KO) mice exhibit enhanced LTP and weak LTD at Schaffer collateral-CA1 synapses in the hippocampus. In accordance with enhanced LTP, Ccny KO mice showed improved spatial learning and memory. However, although previous studies reported that normal LTD is necessary for memory flexibility, Ccny KO mice intriguingly showed improved memory flexibility, suggesting that weak LTD could exert memory flexibility when combined with enhanced LTP. At the molecular level, CCNY modulated spatial learning and memory flexibility by distinctively …

The present invention relates to a composition for preventing or treating Alzheimer’s disease, containing an inhibitor of ATL2, and a method of diagnosing the disease based on the measurement of the ATL2. In the present invention, it was found that PS1 mutants may result in mitochondrial dysfunction, such as increased binding between endoplasmic reticulum and mitochondria, increased mitochondrial ROS production, decreased mitochondrial membrane potential, decreased ATP production, decreased complex I activity, and decreased peroxidase activity, in brain glioma cells and that the PS1 mutants may abnormally increase the binding between endoplasmic reticulum and mitochondria by elevating the expression of the ATL2 in the brain. In addition, when the ATL2 was knocked down, it was observed that the binding between endoplasmic reticulum and mitochondria was lowered and that the expression of …

A composition, for inducing chondrocyte differentiation or regenerating cartilage tissue or both, includes exosomes derived from stem cells differentiating into chondrocytes.

The present disclosure relates to an exosome comprising a photocleavable protein and a use thereof, and the exosome according to the present disclosure contains a fusion protein comprising a blue fluorescent protein (TagBFP), a photocleavable protein (mMaple3), and an exosome-specific marker protein (CD9), and it has been found that when light of 405 nm is irradiated to the exosome, the photocleavable protein, mMaple3 is cleaved and thereby the blue fluorescent protein in the exosome can be delivered into a target cell. In addition, it has been found that Cre protein in the exosome can be delivered into an animal organ, when light of 405 nm is irradiated to an exosome containing Cre fusion protein (Cre-mMaple3-CD9). Therefore, the exosome containing the photocleavable protein according to the present disclosure is expected to be useful in the protein treatment field by safely and efficiently delivering …

BackgroundBile acids (BAs), which act in the liver-brain axis, are liver-derived signaling molecules found in the brain. However, how they modulate neurological function remains largely unknown.MethodsTo assess the role of BAs in the brain, we generated mice with absent 12α-hydroxylase (Cyp8b1), a BA synthesis enzyme, and determined if brain BA levels were altered in these mice, and if and how this may modulate neuronal function.ResultsThe absence of CYP8B1 increased brain levels of the primary BA chenodeoxycholic acid (CDCA), and decreased ischemic stroke infarct area. Furthermore, CDCA administration reduced ischemic stroke lesion area in wild-type mice. Excitotoxicity due to elevated extra-cellular glutamate contributes to neuronal death in ischemic stroke. Neurons from Cyp8b1-/- mice showed reduced susceptibility to glutamate-induced toxicity, and exogenous CDCA reduced glutamate-induced toxicity in neurons from wild-type mice. These data suggest that CDCA-mediated decreases in excitotoxic neuronal death contributes to the reduced stroke lesion area in Cyp8b1-/- mice. Aberrant N-methyl-D-aspartate receptor (NMDAR) over-activation contributes to excitotoxicity. CDCA decreased NMDAR-mediated excitatory post-synaptic currents (EPSCs) in wild-type brain slices, by reducing over-activation of the NMDAR subunit GluN2B. In line with this, synaptic NMDAR activity was also decreased in Cyp8b1-/- brain slices. Expression level and synaptic distribution of GluN2B were unaltered in Cyp8b1-/- mice, suggesting that CDCA may directly antagonize GluN2B-containing NMDARs.ConclusionsOur data suggests that …

Background-Chronic cerebral hypoperfusion (CCH) is an important pathophysiological mechanism of vascular cognitive impairment (VCI). The heterogeneous effects of CCH complicate establishing single target therapies against VCI and its more severe form, vascular dementia (VaD). Intermittent fasting (IF) has multiple targets and is neuroprotective across a range of disease conditions including stroke, but its effects against CCH-induced neurovascular pathologies remain to be elucidated. We therefore assessed the effect of IF against CCH-associated neurovascular pathologies and investigated its underlying mechanisms.Methods-Male C57BL/6NTac mice were subjected to either ad libitum feeding (AL) or IF (16 hours of fasting per day) for 4 months. In both groups, CCH was experimentally induced by the bilateral common carotid artery stenosis (BCAS) method. Sham operated groups were used as controls …

There is an increasing prevalence of Vascular Cognitive Impairment (VCI) worldwide, and several studies have suggested that Chronic Cerebral Hypoperfusion (CCH) plays a critical role in disease onset and progression. However, there is a limited understanding of the underlying pathophysiology of VCI, especially in relation to CCH. Neuroinflammation is a significant contributor in the progression of VCI as increased systemic levels of the proinflammatory cytokine interleukin-1β (IL-1β) has been extensively reported in VCI patients. Recently it has been established that CCH can activate the inflammasome signaling pathways, involving NLRP3 and AIM2 inflammasomes that critically regulate IL-1β production. Given that neuroinflammation is an early event in VCI, it is important that we understand its molecular and cellular mechanisms to enable development of disease-modifying treatments to reduce the …

Severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) entry is mediated by the interaction of the viral spike (S) protein with angiotensin‐converting enzyme 2 (ACE2) on the host cell surface. Although a clinical trial testing soluble ACE2 (sACE2) for COVID‐19 is currently ongoing, our understanding of the delivery of sACE2 via small extracellular vesicles (sEVs) is still rudimentary. With excellent biocompatibility allowing for the effective delivery of molecular cargos, sEVs are broadly studied as nanoscale protein carriers. In order to exploit the potential of sEVs, we design truncated CD9 scaffolds to display sACE2 on the sEV surface as a decoy receptor for the S protein of SARS‐CoV‐2. Moreover, to enhance the sACE2‐S binding interaction, we employ sACE2 variants. sACE2‐loaded sEVs exhibit typical sEVs characteristics and bind to the S protein. Furthermore, engineered sEVs inhibit the entry of wild …

Intermittent fasting (IF) remains the most effective intervention to achieve robust anti-aging effects and attenuation of age-related diseases in various species. Epigenetic modifications mediate the biological effects of several environmental factors on gene expression; however, no information is available on the effects of IF on the epigenome. Here, we first found that IF for 3 months caused modulation of H3K9 trimethylation (H3K9me3) in the cerebellum, which in turn orchestrated a plethora of transcriptomic changes involved in robust metabolic switching processes commonly observed during IF. Second, a portion of both the epigenomic and transcriptomic modulations induced by IF was remarkably preserved for at least 3 months post-IF refeeding, indicating that memory of IF-induced epigenetic changes was maintained. Notably, though, we found that termination of IF resulted in a loss of H3K9me3 regulation of the …