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1,314 result(s) for "Park, Tae Ju"
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Crk1/2-dependent signaling is necessary for podocyte foot process spreading in mouse models of glomerular disease
The morphology of healthy podocyte foot processes is necessary for maintaining the characteristics of the kidney filtration barrier. In most forms of glomerular disease, abnormal filter barrier function results when podocytes undergo foot process spreading and retraction by remodeling their cytoskeletal architecture and intercellular junctions during a process known as effacement. The cell adhesion protein nephrin is necessary for establishing the morphology of the kidney podocyte in development by transducing from the specialized podocyte intercellular junction phosphorylation-mediated signals that regulate cytoskeletal dynamics. The present studies extend our understanding of nephrin function by showing that nephrin activation in cultured podocytes induced actin dynamics necessary for lamellipodial protrusion. This process required a PI3K-, Cas-, and Crk1/2-dependent signaling mechanism distinct from the previously described nephrin-Nck1/2 pathway necessary for assembly and polymerization of actin filaments. Our present findings also support the hypothesis that mechanisms governing lamellipodial protrusion in culture are similar to those used in vivo during foot process effacement in a subset of glomerular diseases. In mice, podocyte-specific deletion of Crk1/2 prevented foot process effacement in one model of podocyte injury and attenuated foot process effacement and associated proteinuria in a delayed fashion in a second model. In humans, focal adhesion kinase and Cas phosphorylation - markers of focal adhesion complex-mediated Crk-dependent signaling - was induced in minimal change disease and membranous nephropathy, but not focal segmental glomerulosclerosis. Together, these observations suggest that activation of a Cas-Crk1/2-dependent complex is necessary for foot process effacement observed in distinct subsets of human glomerular diseases.
Neuroprotective effects of osmotin in Parkinson’s disease-associated pathology via the AdipoR1/MAPK/AMPK/mTOR signaling pathways
Background Parkinson’s disease (PD) is the second most frequent age-related neurodegenerative disorder and is characterized by the loss of dopaminergic neurons. Both environmental and genetic aspects are involved in the pathogenesis of PD. Osmotin is a structural and functional homolog of adiponectin, which regulates the phosphorylation of 5′ adenosine monophosphate-activated protein kinase (AMPK) via adiponectin receptor 1 (AdipoR1), thus attenuating PD-associated pathology. Therefore, the current study investigated the neuroprotective effects of osmotin using in vitro and in vivo models of PD. Methods The study used 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced and neuron-specific enolase promoter human alpha-synuclein (NSE-hαSyn) transgenic mouse models and 1-methyl-4-phenylpyridinium (MPP + )- or alpha-synuclein A53T-treated cell models. MPTP was injected at a dose of 30 mg/kg/day for five days, and osmotin was injected twice a week at a dose of 15 mg/kg for five weeks. We performed behavioral tests and analyzed the biochemical and molecular changes in the substantia nigra pars compacta (SNpc) and the striatum. Results Based on our study, osmotin mitigated MPTP- and α-synuclein-induced motor dysfunction by upregulating the nuclear receptor-related 1 protein (Nurr1) transcription factor and its downstream markers tyrosine hydroxylase (TH), dopamine transporter (DAT), and vesicular monoamine transporter 2 (VMAT2). From a pathological perspective, osmotin ameliorated neuronal cell death and neuroinflammation by regulating the mitogen-activated protein kinase (MAPK) signaling pathway. Additionally, osmotin alleviated the accumulation of α-synuclein by promoting the AMPK/mammalian target of rapamycin (mTOR) autophagy signaling pathway. Finally, in nonmotor symptoms of PD, such as cognitive deficits, osmotin restored synaptic deficits, thereby improving cognitive impairment in MPTP- and α-synuclein-induced mice. Conclusions Therefore, our findings indicated that osmotin significantly rescued MPTP/α-synuclein-mediated PD neuropathology. Altogether, these results suggest that osmotin has potential neuroprotective effects in PD neuropathology and may provide opportunities to develop novel therapeutic interventions for the treatment of PD.
Antioxidant and Neuroprotective Effects of Caffeine against Alzheimer’s and Parkinson’s Disease: Insight into the Role of Nrf-2 and A2AR Signaling
This paper reviews the results of studies conducted on the role of caffeine in the management of different neurological disorders, such as Parkinson’s disease (PD) and Alzheimer’s disease (AD). To highlight the potential role of caffeine in managing different neurodegenerative diseases, we identified studies by searching PubMed, Web of Science, and Google Scholar by scrutinizing the lists of pertinent publications. According to the collected overall findings, caffeine may reduce the elevated oxidative stress; inhibit the activation of adenosine A2A, thereby regulating the accumulation of Aβ; reduce the hyperphosphorylation of tau; and reduce the accumulation of misfolded proteins, such as α-synuclein, in Alzheimer’s and Parkinson’s diseases. The studies have suggested that caffeine has promising protective effects against different neurodegenerative diseases and that these effects may be used to tackle the neurological diseases and/or their consequences. Here, we review the ongoing research on the role of caffeine in the management of different neurodegenerative disorders, focusing on AD and PD. The current findings suggest that caffeine produces potent antioxidant, inflammatory, and anti-apoptotic effects against different models of neurodegenerative disease, including AD, PD, and other neurodegenerative disorders. Caffeine has shown strong antagonistic effects against the adenosine A2A receptor, which is a microglial receptor, and strong agonistic effects against nuclear-related factor-2 (Nrf-2), thereby regulating the cellular homeostasis at the brain by reducing oxidative stress, neuroinflammation, regulating the accumulation of α-synuclein in PD and tau hyperphosphorylation, amyloidogenesis, and synaptic deficits in AD, which are the cardinal features of these neurodegenerative diseases.
The adaptor protein CRK is a pro-apoptotic transducer of endoplasmic reticulum stress
The signalling pathway by which ER damage triggers apoptosis remains unclear. Oakes and colleagues identify CT10-regulated kinase (CRK) as a pro-apoptotic protein induced by ER stress. Such stress leads to the accumulation of cleaved CRK fragments at mitochondria, sensitizing them to cytochrome c release in a cell-free system. Excessive demands on the protein-folding capacity of the endoplasmic reticulum (ER) cause irremediable ER stress and contribute to cell loss in a number of cell degenerative diseases, including type 2 diabetes and neurodegeneration 1 , 2 . The signals communicating catastrophic ER damage to the mitochondrial apoptotic machinery remain poorly understood 3 , 4 , 5 , 6 . We used a biochemical approach to purify a cytosolic activity induced by ER stress that causes release of cytochrome c from isolated mitochondria. We discovered that the principal component of the purified pro-apoptotic activity is the proto-oncoprotein CRK (CT10-regulated kinase), an adaptor protein with no known catalytic activity 7 . C r k −/− cells are strongly resistant to ER-stress-induced apoptosis. Moreover, CRK is cleaved in response to ER stress to generate an amino-terminal M r ∼14K fragment with greatly enhanced cytotoxic potential. We identified a putative BH3 (BCL2 homology 3) domain within this N-terminal CRK fragment, which sensitizes isolated mitochondria to cytochrome c release and when mutated significantly reduces the apoptotic activity of CRK in vivo . Together these results identify CRK as a pro-apoptotic protein that signals irremediable ER stress to the mitochondrial execution machinery.
Gut Microbiota, Its Role in Induction of Alzheimer’s Disease Pathology, and Possible Therapeutic Interventions: Special Focus on Anthocyanins
The human gut is a safe environment for several microbes that are symbiotic and important for the wellbeing of human health. However, studies on gut microbiota in different animals have suggested that changes in the composition and structure of these microbes may promote gut inflammation by releasing inflammatory cytokines and lipopolysaccharides, gut-wall leakage, and may affect systemic inflammatory and immune mechanisms that are important for the normal functioning of the body. There are many factors that aid in the gut’s dysbiosis and neuroinflammation, including high stress levels, lack of sleep, fatty and processed foods, and the prolonged use of antibiotics. These neurotoxic mechanisms of dysbiosis may increase susceptibility to Alzheimer’s disease (AD) and other neurodegenerative conditions. Therefore, studies have recently been conducted to tackle AD-like conditions by specifically targeting gut microbes that need further elucidation. It was suggested that gut dyshomeostasis may be regulated by using available options, including the use of flavonoids such as anthocyanins, and restriction of the use of high-fatty-acid-containing food. In this review, we summarize the gut microbiota, factors promoting it, and possible therapeutic interventions especially focused on the therapeutic potential of natural dietary polyflavonoid anthocyanins. Our study strongly suggests that gut dysbiosis and systemic inflammation are critically involved in the development of neurodegenerative disorders, and the natural intake of these flavonoids may provide new therapeutic opportunities for preclinical or clinical studies.
Multifaceted neuroprotective approach of Trolox in Alzheimer's disease mouse model: targeting Aβ pathology, neuroinflammation, oxidative stress, and synaptic dysfunction
Alzheimer's disease (AD) is a progressive neurodegenerative disorder pathologically characterized by the deposition of amyloid beta (Aβ) plaques and neurofibrillary tangles (NFTs) in the brain. The accumulation of these aggregated proteins causes memory and synaptic dysfunction, neuroinflammation, and oxidative stress. This research study is significant as it aims to assess the neuroprotective properties of vitamin E (VE) analog Trolox in an Aβ 1 − 42 -induced AD mouse model. Aβ 1 − 42 5μL/5min/mouse was injected intracerebroventricularly (i.c.v.) into wild-type adult mice brain to induce AD-like neurotoxicity. For biochemical analysis, Western blotting and confocal microscopy were performed. Remarkably, intraperitoneal (i.p.) treatment of Trolox (30 mg/kg/mouse for 2 weeks) reduced the AD pathology by reducing the expression of Aβ, phosphorylated tau (p-tau), and β-site amyloid precursor protein cleaving enzyme1 (BACE1) in both cortex and hippocampus regions of mice brain. Furthermore, Trolox-treatment decreased neuroinflammation by inhibiting Toll-like receptor 4 (TLR4), phosphorylated nuclear factor-κB (pNF-κB) and interleukin-1β (IL-1β), and other inflammatory biomarkers of glial cells [ionized calcium-binding adaptor molecule 1 (Iba1) and glial fibrillary acidic protein (GFAP)]. Moreover, Trolox reduced oxidative stress by enhancing the expression of nuclear factor erythroid-related factor 2 (NRF2) and heme oxygenase 1 (HO1). Similarly, Trolox-induced synaptic markers, including synaptosomal associated protein 23 (SNAP23), synaptophysin (SYN), and post-synaptic density protein 95 (PSD-95), and memory functions in AD mice. Our findings could provide a useful and novel strategy for investigating new medications to treat AD-associated neurodegenerative diseases.
Ambroxol confers neuroprotection against scopolamine-induced Alzheimer’s-like pathology by modulating oxidative stress, neuroinflammation, and cognitive deficits via Nrf-2/JNK/GSK-3β signaling pathways
Alzheimer’s disease (AD) is the most common and costly chronic progressive neurodegenerative disorder, with the highest impact on public health worldwide. Pathological hallmarks of AD include progressive cognitive decline and memory impairment, dominantly mediated by oxidative neurodegeneration. Oxidative stress is commonly recognized as a key factor in the pathophysiological progression of AD. Despite significant advancements, a definitive and effective therapeutic intervention for AD remains elusive. In this study, we investigate the neuroprotective potential of ambroxol (Amb), known for its potent anti-inflammatory and antioxidant properties. Given ambroxol’s potential neuroprotective effects, we explore the underlying molecular mechanisms, explicitly examining its role in attenuating scopolamine-induced oxidative stress-mediated activation of the c-Jun N-terminal kinase (JNK) pathway, as well as its modulation of Akt and glycogen synthase kinase-3 beta (GSK-3β) signaling, which is a key contributor to neuroinflammation, synaptic dysfunction and neurodegeneration. AD pathology is induced by scopolamine administration, leading to excessive lipid peroxidation (LPO) and reactive oxygen species (ROS) generation, which leads to a decline in critical antioxidant proteins, including nuclear factor erythroid 2-related factor 2 (Nrf-2) and heme oxygenase-1 (HO-1). However, ambroxol treatment effectively attenuated oxidative stress by reducing the production of reactive oxidative species while restoring the expression of key antioxidant proteins. Similarly, ambroxol attenuated oxidative stress-induced JNK activation and modulated Akt and GSK-3β alterations. Immunofluorescence and western blot analyses revealed that ambroxol attenuated reactive gliosis by suppressing the expression of GFAP and Iba-1, alongside the downregulation of key pro-inflammatory mediators, such as IL-1β, TNF-α, and phosphorylated NF-κB (p-p65). Scopolamine also compromised synaptic integrity and induced deficits in memory formation and spatial learning. In contrast, ambroxol promoted synaptic integrity by upregulating the expression of SNAP-23 and PSD-95, thereby ameliorating scopolamine-induced impairments in spatial learning and memory.
Osmotin-derived 9-amino-acid peptide alleviates α-synuclein and MPTP-induced glial cell activation mediated neuroinflammation, protecting dopaminergic neurons in Parkinson’s disease mice brain
Background Parkinson’s disease (PD) is the second most common neurodegenerative disorder, categorized by the loss of dopaminergic neurons in the brain’s Substantia Nigra pars compacta (SNpc) due to α-synuclein (α-syn) aggregation, leading to reduced dopamine levels in the striatum. This research study evaluates the neuroprotective potential of the novel peptide osmotin-derived 9-amino-acid (Os_9aa, C-T-Q-G-P-C-G-P-T) against α-syn (neuron-specific enolase promoter human alpha-synuclein (NSE-hαSyn)) and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD models. Methods Human neuroblastoma SH-SY5Y cells were employed as an in vitro model, while NSE-hαSyn (α-synuclein) transgenic mice and MPTP-treated mice were used as in vivo models of PD. MPTP was administered intraperitoneally (30 mg/kg) once daily for five consecutive days. Mice were immunized with Os_9aa (15 mg/kg, i.p., twice weekly for five weeks), followed by behavioral assessments including open field test, wire hang test, pole test, and rotarod test, and biochemical analysis using the Triplex Assay, western blotting, and confocal microscopy. Results Our study demonstrated that the novel peptide Os_9aa enhanced cell viability, reduced cytotoxicity, and apoptosis in SH-SY5Y neuroblastoma cells. Os_9aa attenuated synucleinopathy-related pathology in NSE-hαSyn transgenic mice and MPTP-induced PD mouse models. Current findings also highlighted the therapeutic potential of Os_9aa in mitigating behavioral deficits observed in NSE-hαSyn and MPTP mouse models of PD. Furthermore, Os_9aa administration effectively restored key dopaminergic markers, including tyrosine hydroxylase (TH), vesicular monoamine transporter 2 (VMAT2), and dopamine transporter (DAT). Additionally, it reduced neuroinflammation by decreasing the activation of glial cells—ionized calcium-binding adaptor molecule 1 (Iba-1) and glial fibrillary acidic protein (GFAP), as well as pro-inflammatory cytokines, such as phosphorylated nuclear factor-κB (p-NF-кB), tumor necrosis factor-α (TNF-α), and interleukin-1β (IL-1β), in the striatum and SNpc regions. Furthermore, Os_9aa mitigated oxidative stress (OS) by upregulating the expression of nuclear factor erythroid-related factor 2 (Nrf-2) and heme oxygenase 1 (HO-1), and improved cognitive performance. Conclusion Collectively, these findings highlight the neuroprotective potential of the Os_9aa, which counteracts α-synuclein– and MPTP-induced neurotoxicity by reducing oxidative stress, glial activation, and neuroinflammation. This multifaceted protection preserves neuronal integrity in both the NSE-hαSyn transgenic and MPTP-induced PD mouse models, underscoring Os_9aa as a promising therapeutic candidate for modifying PD pathogenesis.
Lupeol restores dopaminergic function by suppressing glial activation in a Parkinson’s disease mouse model
Parkinson's disease (PD) is a progressive neurodegenerative disorder marked by chronic neuroinflammation and loss of dopaminergic neurons. The neurotoxin MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine) selectively targets dopaminergic neurons, effectively replicating the pathological features of PD. Lupeol, a natural pentacyclic triterpenoid, has been shown to exhibit neuroprotective properties in various models by reducing oxidative stress, inflammation, and apoptosis. This study aimed to investigate the neuroprotective effects of lupeol in an MPTP-induced mouse model of PD. Male mice were administered MPTP (30 mg/kg, i.p.) for seven days to induce PD-like pathology. Lupeol (50 mg/kg) was administered as a potential therapeutic intervention. Behavioral assessments were conducted to evaluate motor function. Biochemical analyses were performed to measure dopamine and tyrosine hydroxylase (TH) levels. Immunohistochemical and molecular approaches were used to assess glial activation, oxidative stress, and apoptotic signaling pathways in the substantia nigra pars compacta (SNpc) and striatum. Lupeol treatment significantly improved MPTP-induced motor impairments and restored dopamine and TH levels. Additionally, lupeol reduced neuroinflammation, by decreasing microglial activation, astrocyte reactivity, and lower levels of inflammatory mediators. Oxidative stress markers, including reactive oxygen species (ROS) and lipid peroxidation (LPO), were diminished in SNpc and striatum following lupeol treatment. Furthermore, lupeol upregulated antioxidant defense mechanisms by increasing the expression of Nrf-2 and HO-1. Apoptotic markers, such as Cytochrome C, Bax, and Caspase-3, were downregulated, indicating reduced neuronal apoptosis. The current study suggests that lupeol exerts neuroprotective effects by inhibiting glial cell activation, thereby reducing neuroinflammation, oxidative stress, and apoptosis in an MPTP-induced PD mouse model.
Ambroxol attenuates detrimental effect of LPS-induced glia-mediated neuroinflammation, oxidative stress, and cognitive dysfunction in mice brain
Neurodegenerative diseases, such as Alzheimer’s disease (AD) and Parkinson’s disease (PD), are multifactorial. Among various factors, lipopolysaccharides (LPSs) from Gram-negative bacteria, such as E. coli , are considered potential causative agents. Despite significant advancements in the field, there is still no cure. In this study, we investigated the neuroprotective effects of ambroxol against LPS-induced neuroinflammation, oxidative stress, neurodegeneration, and the associated cognitive dysfunction. Intraperitoneal injection of LPS (250 µg/kg every alternative day for a total of seven doses over 14 days) triggered glial cell activation, neuroinflammation, oxidative stress, and neurodegeneration in the mouse brain. Ambroxol treatment (30 mg/kg/day for 14 days) significantly reduced neuroinflammation and oxidative stress compared to LPS-treated mice. Immunoblotting and immunofluorescence results showed that ambroxol reduced levels of Toll-like receptor 4 (TLR4) and oxidative stress kinase phospho-c-Jun N-terminal Kinase 1 (p-JNK). It also decreased astrocyte and microglia activation in the cortex and hippocampus of LPS+ Amb-treated mice, as indicated by the downregulation of GFAP and Iba-1. Furthermore, ambroxol-reversed LPS-induced neuroinflammation by inhibiting inflammatory mediators, such as IL-1β and TNF-α, through regulation of the transcription factor p-NFkB. Persistent neuroinflammation disrupted the natural antioxidant mechanisms, leading to oxidative stress. Ambroxol treatment upregulated antioxidant markers, including Nrf-2, HO-1, and SOD, which were downregulated in the LPS-treated group. Additionally, ambroxol-inhibited lipid peroxidation, maintaining malondialdehyde levels in the mouse brain. Ambroxol also improves synaptic integrity by upregulating synaptic biomarkers, including PSD-95 and SNAP-23. Overall, ambroxol demonstrated anti-inflammatory, antioxidant, and neuroprotective effects in LPS-treated mice, highlighting its potential benefits in neurological disorders.