Publications by authors named "Youngkyoung Lee"

Cellular senescence, recognized as a key hallmark of aging, leads to the accumulation of senescent cells in various tissues over time. While the detrimental effects of these cells on age-related pathological conditions are well-documented, there is still limited information about how senescent cells are distributed in normal tissues of both young and aged organs. Our research indicates that fully senescent p16 cells are rarely identified in the parenchyma of organic tissues and in the stromal cells crucial for structural maintenance, such as fibroblasts and smooth muscle cells.

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Background: Tuberculosis is a highly contagious disease caused by Mycobacterium tuberculosis, and the increase in antibiotic resistance threatens humankind. Therefore, there is an urgent need to develop new anti-tuberculosis drugs that can overcome the limitations of existing drugs. Here, we report the anti-tuberculosis effect of microbiome therapeutic PMC205, a strain of Bacillus subtilis.

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Article Synopsis
  • - This study investigates how colorectal cancer progresses, particularly the shift towards more aggressive, metastatic behavior as tumors invade surrounding tissues.
  • - It defines "evolution" as the transition from structured tumor formations to invasive cancer cell growth, focusing on cancer cell buddings at the invasive front.
  • - The research identifies two types of senescent tumor cells (Type I and Type II) that contribute differently to cancer progression, with Type II being significant for local invasion and lymph node metastasis, which may influence patient outcomes.
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The biological process of aging is thought to result in part from accumulation of senescent cells in organs. However, the present study identified a subset of fibroblasts and smooth muscle cells which are the major constituents of organ stroma neither proliferative nor senescent in tissues of the elderly, which we termed "mid-old status" cells. Upregulation of pro-inflammatory genes (IL1B and SAA1) and downregulation of anti-inflammatory genes (SLIT2 and CXCL12) were detected in mid-old cells.

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Article Synopsis
  • NGS technology is advancing microbiome research, particularly in the study of fermented foods like bokbunja vinegar in Korea.
  • The study involved a 70-day fermentation under various conditions, analyzing physicochemical properties, organic acids, microbial communities, and taste using an electronic tongue.
  • Three distinct fermentation patterns were identified based on fermentation method and conditions, contributing to the understanding of vinegar's flavor and quality, which could enhance traditional vinegar production.
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Background: The excessive production and accumulation of melanin in the epidermal skin layer can result in skin hyperpigmentation and darkening. Current technologies for regulating melanin are based on inhibiting melanin biosynthesis. They have low effectiveness and safety issues.

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Senescent tumor cells are nonproliferating tumor cells which are closely related to cancer progression by secreting senescence-related molecules, called senescence-associated secreting phenotypes. Therefore, the presence of senescent tumor cells is considered a prognostic factor in various cancer types. Although senescence-associated β-galactosidase staining is considered the best marker for detection of senescent tumor cells, it can only be performed in fresh-frozen tissues.

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An imbalanced gut microbiome has been linked to a higher risk of many bone-related diseases. The objective of this study was to discover biomarkers of osteoporosis (OP). So, we collected 76 stool samples (60 human controls and 16 OP patients), extracted DNA, and performed 16S ribosomal ribonucleic acid (rRNA) gene-based amplicon sequencing.

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Outbreaks of carbapenem-resistant (CRE), especially (CRKP), are commonly reported as severe infections in hospitals and long-term care settings, and their occurrence is increasing globally. Conventional antibiotics used for treating CRE have become ineffective due to resistance development. Furthermore, their safety issues restrict their availability and use for CRE treatment.

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Tuberculosis, an infectious disease, is one of the leading causes of death worldwide. Drug-resistant tuberculosis exacerbates its threat. Despite long-term and costly treatment with second-line drugs, treatment failure rates and mortality remain high.

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While mitochondrial bioenergetic deregulation has long been implicated in cellular senescence, its mechanistic involvement remains unclear. By leveraging diverse mitochondria-related gene expression profiles derived from two different cellular senescence models of human diploid fibroblasts, we found that the expression of mitoribosomal proteins (MRPs) was generally decreased during the early-to-middle transition prior to the exhibition of noticeable SA-β-gal activity. Suppressed expression patterns of the identified senescence-associated MRP signatures (SA-MRPs) were validated in aged human cells and rat and mouse skin tissues and in aging mouse fibroblasts at single-cell resolution.

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Mycobacterium tuberculosis (M. tb), the etiological agent of tuberculosis (TB), poses a severe challenge for public health and remains the number one cause of death as a single infectious agent. There are 10 million active cases of TB per year with 1.

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Deregulated mitochondrial energetics is a metabolic hallmark of cancer cells. However, the causative mechanism of the bioenergetic deregulation is not clear. In this study, we show that somatic copy number alteration (SCNA) of mitoribosomal protein (MRP) genes is a key mechanism of bioenergetic deregulation in hepatocellular carcinoma (HCC).

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Tuberculosis, an infectious disease, is caused by Mycobacterium tuberculosis. It remains a significant public health issue around the globe, causing about 1.8 million deaths every year.

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Tuberculosis is a highly contagious disease caused by . It affects about 10 million people each year and is still one of the leading causes of death worldwide. About 2 to 3 billion people (equivalent to 1 in 3 people in the world) are infected with latent tuberculosis.

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Cellular senescence can either support or inhibit cancer progression. Here, it is shown that intratumoral infiltration of CD8 T cells is negatively associated with the proportion of senescent tumor cells in colorectal cancer (CRC). Gene expression analysis reveals increased expression of C-X-C motif chemokine ligand 12 (CXCL12) and colony stimulating factor 1 (CSF1) in senescent tumor cells.

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Mitochondrial respiratory defects have been implicated in cancer progression and metastasis, but how they control tumor cell aggressiveness remains unclear. Here, we demonstrate that a mitochondrial respiratory defect induces nuclear factor-erythroid 2 like 1 (NFE2L1) expression at the transcriptional level via reactive oxygen species (ROS)-mediated STAT3 activation. We identified syntaxin 12 (STX12) as an effective downstream target of NFE2L1 by performing cDNA microarray analysis after the overexpression and depletion of NFE2L1 in hepatoma cells.

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Mitochondrial ribosomes (mitoribosomes), the specialized translational machinery for mitochondrial genes, exclusively encode the subunits of the oxidative phosphorylation (OXPHOS) system. Although OXPHOS dysfunctions are associated with hepatic disorders including hepatocellular carcinoma (HCC), their underlying mechanisms remain poorly elucidated. In this study, we aimed to investigate the effects of mitoribosome defects on OXPHOS and HCC progression.

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Overproduction and accumulation of melanin in the skin will darken the skin and cause skin disorders. So far, components that can inhibit tyrosinase, a melanin synthase of melanocytes, have been developed and used as ingredients of cosmetics or pharmaceutical products. However, most of existing substances can only inhibit the biosynthesis of melanin while melanin that is already synthesized and deposited is not directly decomposed.

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Aerobic glycolysis and mitochondrial dysfunction are key metabolic features of cancer cells, but their interplay during cancer development remains unclear. We previously reported that human hepatoma cells with mitochondrial defects exhibit down-regulated lactate dehydrogenase subunit B (LDHB) expression. Here, using several molecular and biochemical assays and informatics analyses, we investigated how LDHB suppression regulates mitochondrial respiratory activity and contributes to liver cancer progression.

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Organismal aging is accompanied by a host of progressive metabolic alterations and an accumulation of senescent cells, along with functional decline and the appearance of multiple diseases. This implies that the metabolic features of cell senescence may contribute to the organism's metabolic changes and be closely linked to age-associated diseases, especially metabolic syndromes. However, there is no clear understanding of senescent metabolic characteristics.

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Article Synopsis
  • Mitochondrial DNA (mtDNA) mutations are common in various cancers, and while links between mitochondrial dysfunction and cancer have been identified, more research is needed to clarify how these mutations promote tumor growth and spread.
  • The researchers created a cell line lacking mtDNA (ρ⁰) to investigate how mitochondrial dysfunction contributes to cancer severity, finding that these cells showed reduced drug-induced cell death and lower levels of key apoptosis-related proteins, such as p53.
  • The decrease in p53 was linked to the activation of nuclear factor-κB, which relied on increased free calcium levels in the cells, pointing to a new understanding of how mitochondrial dysfunction can lead to greater tumor aggressiveness and resistance to treatment.
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Impaired mitochondrial oxidative phosphorylation (OXPHOS) capacity, accompanied by enhanced glycolysis, is a key metabolic feature of cancer cells, but its underlying mechanism remains unclear. Previously, we reported that human hepatoma cells that harbor OXPHOS defects exhibit high tumor cell invasiveness via elevated claudin-1 (CLN1). In the present study, we show that OXPHOS-defective hepatoma cells (SNU354 and SNU423 cell lines) exhibit reduced expression of mitochondrial ribosomal protein L13 (MRPL13), a mitochondrial ribosome (mitoribosome) subunit, suggesting a ribosomal defect.

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As senescence develops, cells sequentially acquire diverse senescent phenotypes along with simultaneous multistage gene reprogramming. It remains unclear what acts as the key regulator of the collective changes in gene expression at initiation of senescent reprogramming. Here we analyzed time series gene expression profiles obtained in two different senescence models in human diploid fibroblasts: replicative senescence and HO-induced senescence.

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