Publications by authors named "Ji Seon Ahn"

The gut microbiome, a complex community of trillions of microorganisms in the intestines, is crucial in maintaining human health. Recent advancements in microbiome research have unveiled a compelling link between the gut microbiome and cancer development and progression. Alterations in the composition and function of the gut microbiome, known as dysbiosis, have been implicated in various types of cancer, including, esophageal, liver, colon, pancreatic, and gastrointestinal.

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  • Theta-gamma coupling (TGC) is important for working memory (WM) and could help understand WM deficits in panic disorder (PD) during tasks like mental arithmetic (MA).
  • A study compared EEG results from 34 PD patients and 34 healthy controls, examining TGC and theta/gamma oscillations during resting states and MA.
  • Findings showed that PD patients had lower TGC and theta power, which correlated with higher anxiety levels; however, during MA, better performance was linked to greater TGC and theta power.
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The gut microbiome is well known for its influence on human physiology and aging. Therefore, we speculate that the gut microbiome may affect muscle strength in the same way as the host's own genes. To demonstrate candidates for gut microbes affecting muscle strength, we remodeled the original gut microbiome of mice into human intestinal microbiome through fecal microbiome transplantation (FMT), using human feces and compared the changes in muscle strength in the same mice before and three months after FMT.

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Purpose: Delirium in the intensive care unit (ICU) poses a significant safety and socioeconomic burden to patients and caregivers. However, invasive interventions for managing delirium have severe drawbacks. To reduce unnecessary interventions during ICU hospitalization, we aimed to investigate the features of delirium among ICU patients according to the occurrence of hypoactive symptoms, which are not expected to require invasive intervention.

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Phytochemicals are increasingly recognized in the field of healthy aging as potential therapeutics against various aging-related diseases. Nutmeg, derived from the tree, is an example. Nutmeg has been extensively studied and proven to possess antioxidant properties that protect against aging and alleviate serious diseases such as cancer, heart disease, and liver disease.

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Given the impact of the gut microbiome on human physiology and aging, it is possible that the gut microbiome may affect locomotion in the same way as the host's own genes. There is not yet any direct evidence linking the gut microbiome to locomotion, though there are some potential connections, such as regular physical activity and the immune system. In this study, we demonstrate that the gut microbiome can contribute differently to locomotion.

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  • - A tic disorder (TD) is a neurodevelopmental condition marked by involuntary movements and sounds, linked to issues in specific brain circuits responsible for sensory processing.
  • - A study compared the resting-state theta-gamma coupling (TGC) of 13 children with TD to 13 healthy peers, revealing that TD patients had significantly lower TGC, indicating potential difficulties in cognitive functions related to attention.
  • - The lower TGC in TD patients suggests a dysfunction in the brain networks vital for processing visual information, indicating they may struggle to filter out irrelevant sensory information when at rest with their eyes closed.
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The precise mechanisms of action of the host's gut microbiome at the level of its constituting bacteria are obscure in most cases despite its definitive role. To study the precise role of the gut microbiome on the phenotypes of a host by excluding host factors, we analyzed two different gut microbiomes within the same individual mouse after replacing the gut microbiome with a new one to exclude the host factors. The gut microbiome of conventional C57BL/6 mice was randomly reestablished by feeding fecal samples from obese humans to the mice, and depleting their original gut microbiome with an antibiotic and antifungal treatment.

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Theta phase-gamma amplitude coupling (TGC) plays an important role in several different cognitive processes. Although spontaneous brain activity at the resting state is crucial in preparing for cognitive performance, the functional role of resting-state TGC remains unclear. To investigate the role of resting-state TGC, electroencephalogram recordings were obtained for 56 healthy volunteers while they were in the resting state, with their eyes closed, and then when they were engaged in a retention interval period in the visual memory task.

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The determining factors of the composition of the gut microbiome are one of the main interests in current science. In this work, we compared the effect of diet shift (DS) from heavily relying on meatatarian diets to vegetarian diets and physical exercise (EX) on the composition of the gut microbiome after 3 months. Although both DS and EX affected the composition of the gut microbiome, the patterns of alteration were different.

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Leucine-rich repeat kinase 2 (LRRK2), a multi-domain protein, is a key causative factor in Parkinson's disease (PD). Identification of novel substrates and the molecular mechanisms underlying the effects of LRRK2 are essential for understanding the pathogenesis of PD. In this study, we showed that LRRK2 played an important role in neuronal cell death by directly phosphorylating and activating apoptosis signal-regulating kinase 1 (ASK1).

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Parkin, an E3 ubiquitin ligase, is the most frequently mutated gene in hereditary Parkinson's disease. Inactivation of Parkin leads to impairment of the ubiquitin-proteasome system, resulting in the accumulation of misfolded or aggregated proteins and ensuing neurodegeneration. In this study, we show that Parkin positively regulates the Notch1 signaling pathway.

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Autophagy is a highly conserved mechanism that degrades long-lived proteins and dysfunctional organelles, and contributes to cell fate. In this study, autophagy attenuates Notch1 signaling by degrading the Notch1 intracellular domain (Notch1-IC). Nutrient-deprivation promotes Notch1-IC phosphorylation by MEKK1 and phosphorylated Notch1-IC is recognized by Fbw7 E3 ligase.

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  • The study identifies HIPK2 as a key kinase that promotes the degradation of Notch1, a receptor linked to cancer progression, by phosphorylating it in a specific degradation motif.
  • Notch1-IC levels are found to be higher in cancer cells compared to normal cells, and under stress conditions, HIPK2 helps keep these levels low through degradation processes.
  • Mutations near the phosphorylation site T2512 on Notch1-IC can prevent its degradation, suggesting potential therapeutic approaches to inhibit Notch1-related cancer progression.
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p21-Activated kinase 1 (PAK1) is a serine/threonine protein kinase implicated in cytoskeletal remodeling and cell motility. Recent studies have shown that it also promotes cell proliferation, regulates apoptosis, and increases cell transformation and invasion. In this study, we showed that NOTCH1 intracellular domain (NOTCH1-IC) negatively regulated PAK1 signaling pathway.

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Fe65 is a highly conserved adaptor protein that interacts with several binding partners. Fe65 binds proteins to mediate various cellular processes. But the interacting partner and the regulatory mechanisms controlled by Fe65 are largely unknown.

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Notch signaling pathway is well known that it is involved in regulating cell fate, proliferation and homeostasis. In this study, we show a novel function of alpha-synuclein (SNCA) to promote degradation of Notch1 intracellular domain (Notch1-IC) through Fbw7, ubiquitin E3 ligase. We identified that SNCA inhibits Notch1 transcription activity and diminishes the interaction between Notch1-IC and RBP-Jk.

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The gamma-secretase is a multiprotein complex that cleaves many type-I membrane proteins, such as the Notch receptor and the amyloid precursor protein. Nicastrin (NCT) is an essential component of the multimeric gamma-secretase complex and functions as a receptor for gamma-secretase substrates. In this study, we found that Akt1 markedly regulated the protein stability of NCT.

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Notch1 genes encode receptors for a signaling pathway that regulates various aspects of cell growth and differentiation; however, the role of Notch1 signaling in p38 mitogen-activated protein kinase (MAPK) signaling pathway is still not well defined. In this study, we found that Notch1 intracellular domain (Notch1-IC) prevents oxidative stress-induced cell death through the suppression of the Apoptosis signal-regulating kinase (ASK) 1 signaling pathway. Notch1-IC inhibited H2O2-induced activation of ASK1 and the activation of downstream kinases in the p38 MAPK signaling cascade.

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Serine-threonine Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) is the key component in noncanonical Wnt5a signaling and has been shown to regulate its signaling. In this study, we found that CaMKII induced by Wnt5a remarkably reduced the protein stability of the silencing mediator of retinoic acid and thyroid hormone receptor (SMRT), a co-repressor of Notch signaling, through proteasomal degradation. Wnt5a was found to enhance Notch1 intracellular domain (Notch1-IC) transcription activity, which could be inhibited by treatment with KN93, a CaMKII inhibitor.

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The gamma-secretase complex is involved in the intramembranous proteolysis of a variety of substrates, including the amyloid precursor protein and the Notch receptor. Nicastrin (NCT) is an essential component of the gamma-secretase complex and functions as a receptor for gamma-secretase substrates. In this study, we determined that serum- and glucocorticoid-induced protein kinase 1 (SGK1) markedly reduced the protein stability of NCT.

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  • - Notch signaling is activated when the Notch receptor is cleaved after interacting with its ligands, and Jagged-1 can also be cleaved to release a fragment called Jagged-1 intracellular domain (JICD).
  • - The study shows that JICD inhibits Notch1 signaling by destabilizing the Notch1 intracellular domain (Notch1-IC), thereby preventing the formation of a key signaling complex.
  • - JICD promotes the degradation of Notch1-IC through the Fbw7 proteasomal pathway, acting as a negative regulator of Notch1 signaling.
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  • * AICD reduces Notch1 signaling by promoting the breakdown of Notch1's active form (Notch1-IC) and a key partner protein (RBP-Jk) through different degradation processes.
  • * The research reveals that AICD acts as a negative regulator in Notch1 signaling by enhancing the degradation of both Notch1-IC and RBP-Jk, affecting their ability to control genetic transcription.
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  • Notch is a key transmembrane protein involved in regulating cell survival, death, and differentiation through the Notch signaling pathway, with mutations in Notch1 and Fbw7 linked to T-ALL leukemia in many patients.
  • This study finds that the protein SGK1 reduces the stability of the active Notch1 protein by promoting its degradation through the Fbw7 protein, suggesting a regulatory role in the Notch signaling pathway.
  • The research confirms that SGK1 phosphorylates Fbw7, which leads to the degradation and ubiquitylation of Notch1, indicating a mechanism by which SGK1 inhibits the Notch signaling pathway.
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