• 치위생과학회지
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• 제23권2호
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• pp.169-175
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• 2023

Background: Although microbial infection is direct cause of periodontal disease, various environmental factors influence the disease severity. Aging is considered a risk factor for oral diseases, with the prevalence of periodontal diseases increasing with age. Moreover, senescence-associated secretory phenotype (SASP) expressed in age-related diseases is a key marker of chronic inflammation and aging phenotypes. Therefore, this study aimed to understand the relevance of senescent cells to periodontal health and disease, investigate the possibility of regulating the expression of aging- and osteolysis-related factors in gingival fibroblasts, and investigate the effect of senescence induction in gingival fibroblasts on osteoclast differentiation in mouse bone marrow-derived macrophages (BMMs). Methods: After stimulation with 400 nM hydrogen peroxidase, human gingival fibroblasts (HGFs) were examined for senescence-associated β-galactosidase. Western blot and enzyme-linked immunosorbent assays were performed to assess the expression of SASP. Osteoclast formation was assessed in BMMs using a conditioned medium (CM) from hydrogen peroxide-stimulated HGFs. Osteoclastic differentiation was investigated using tartrate-resistant acid phosphatase (TRAP) staining and activity. Data analysis was performed using SPSS version 25.0. Results: The expression of senescence-related molecules, including p53, p16, and p21, and the expression of osteolytic factors, including IL-6, IL-8, and IL-17, were found to be significantly higher in the hydrogen peroxide-stimulated HGF than in the control group. Regarding the indirect effects of senescent gingival cells, the number of osteoclasts and TRAP activity increased according to the differentiation of BMM cultured in CM. Conclusion: Our results on the of between osteolytic factors and cellular senescence in gingival fibroblast cells helped to reveal evidence of pathological aging mechanisms. Furthermore, our results suggest that the development of novel therapies that target specific SASP factors could be an effective treatment strategy for periodontal disease.

• Biomolecules & Therapeutics
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• 제25권5호
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• pp.511-518
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• 2017

Ultraviolet (UV) irradiation is a relevant environment factor to induce cellular senescence and photoaging. Both autophagy- and silent information regulator T1 (SIRT1)-dependent pathways are critical cellular processes of not only maintaining normal cellular functions, but also protecting cellular senescence in skin exposed to UV irradiation. In the present studies, we investigated whether modulation of autophagy induction using a novel synthetic SIRT1 activator, heptasodium hexacarboxymethyl dipeptide-12 (named as Aquatide), suppresses the UVB irradiation-induced skin aging. Treatment with Aquatide directly activates SIRT1 and stimulates autophagy induction in cultured human dermal fibroblasts. Next, we found that Aquatide-mediated activation of SIRT1 increases autophagy induction via deacetylation of forkhead box class O (FOXO) 1. Finally, UVB irradiation-induced cellular senescence measured by $SA-{\beta}-gal$ staining was significantly decreased in cells treated with Aquatide in parallel to occurring SIRT1 activation-dependent autophagy. Together, Aquatide modulates autophagy through SIRT1 activation, contributing to suppression of skin aging caused by UV irradiation.

• Toxicological Research
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• 제19권3호
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• pp.161-172
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• 2003

Explanted mammalian cells perform a limited number of cell division in vitro and than are arrested in a state known as replicative senescence. Such cells are irreversibly blocked, mostly in the G1 phase of cell cycle, and are no longer sensitive to growth factor stimulation. Thus replicative senescence is defined as a permanent and irreversible loss of replicative potential of cells. For this characteristic, replicative senescence seems to evolve to protect mammalian organism from cancer. However, senescence also contributes to aging. It seems to decrease with age of the cell donor and, as a form of cell senescence, is thought to underlie the aging process. Extensive evidence supports the idea that progressive telomere loss contributes to the phenomenon of cell senescence. Telomeres are repetitive structures of the sequence (TTAGGG)n at the ends of linear chromosomes. It has been shown that the average length of telomere repeats in human somatic cells decreases by 30∼200 bp with each cell division. It is generally believed that when telomeres reach a critical length, a signal is activated to initiate the senescent program. This has given rise to the hypothesis that telomeres act as mitotic clocks to regulate lifespan. One proposes that cumulative oxidative stress, mainly reactive oxygen species generated from mitochondria, may mainly cause telomere shortening, accelerating aging. Here, the biological importance and mechanism of replicative senescence were briefly reviewed. Also it was summarized that how oxidative stress affects replicative senescence and telomere shortening.

• 생명과학회지
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• 제18권3호
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• pp.344-349
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• 2008

이 논문에서는 신생아와 노인 유래의 섬유아세포들의 노화의 특징들을 비교하여 사람의 나이와 세포의 수명 및 세포 형질의 관계에 대해 연구하였다. 본 연구의 결과는 비록 한가지의 노인세포에 대해 얻어진 것이기는 하지만 다음과 같은 세 가지 중요한 가능성을 제시한다. 첫째로, 노인에서 유래한 섬유아세포의 증식속도가 신생아 유래의 세포에 비해서 느릴 가능성이 있다. 이러한 결과는 실제로 노인 신체에 존재하는 세포가 신생아에 존재하는 세포에 비해 낮은 속도로 증식할 가능성을 시사하는 것으로서, 노인에서 관찰되는 조직실질의 감소 원인을 설명하는 자료가 될 수 있겠다. 둘째로, 노인 유래 섬유아세포의 early passage 세포가 신생아 유래의 세포의 early passage 세포와 동일하게 낮은 수준의 SA ${\beta}-Gal$ 활성, autofluorescence, lysosome 함량, 그리고 활성산소 수준을 갖고 있었다. 이 점은, early passage 때의 세포가 보이는 형질이 신체에 존재하는 세포의 상황과 크게 다르지 않다고 가정할 때, 노인 신체의 조직에 존재하는 세포들이 신생아의 세포와 유사한 상태로 존재할 가능성을 시사하는 것이다. 즉, 노인 신체에서는 in vitro 노화세포에서 나타나는 수준의 세포노화가 일어나 있지 않다는 것이다. 셋째, 노인세포가 노화했을 때는 신생아세포의 경우와 거의 동일한 수준의 활성산소, lysosome, SA ${\beta}-Gal$ activity 증가를 보이고 있었는데, 이는 노인 유래의 세포가 in vitro 배양 시 신생아 유래의 세포보다 더 심하거나 또는 빠른 산화적 손상이나 세포학적 변화를 겪지는 않는다는 것을 보여주는 것으로서, 세포가 보유한 항산화적 기능이 노인이 되면서 크게 약화되지는 않음을 시사하고 있다. 결론적으로 노인 유래의 세포는 세포증식 속도를 제외하면 대체로 신생아 때의 상태와 동일한 세포 내 상태를 갖고 있다고 결론 내릴 수 있겠다.

• 대한약침학회지
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• 제20권3호
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• pp.213-219
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• 2017

Objectives: Based on data from Chinese and Indian traditional herbal medicines, gum resin of Ferula assa-foetida (sometimes referred to asafetida or asafoetida) has several therapeutic applications. The authors of various studies have claimed that asafetida has cytotoxic, antiulcer, anti-neoplasm, anti-cancer, and anti-oxidative effects. In present study, the anti-aging effect of asafetida on senescent human dermal fibroblasts was evaluated. Methods: Senescence was induced in in vitro cultured human dermal fibroblasts (HDFs) through exposure to $H_2O_2$, and the incidence of senescence was recognized by using cytochemical staining for the activity of ${\beta}$-galactosidase. Then, treatment with oleo gum resin of asafetida was started to evaluate its rejuvenating effect. The survival rate of fibroblasts was evaluated by using methyl tetrazolium bromide (MTT) assays. Real-time quantitative reverse transcription-polymerase chain reaction (qRT-PCR) and western blot assays were performed to evaluate the expressions of apoptotic and anti-apoptotic markers. Results: Our experiments show that asafetida in concentrations ranging from $5{\times}10^{-8}$ to $10^{-7}g/mL$ has revitalizing effects on senescent fibroblasts and significantly reduces the ${\beta}$-galactosidase activity in these cells (P < 0.05). Likewise, treatment at these concentrations increases the proliferation rate of normal fibroblasts (P < 0.05). However, at concentrations higher than $5{\times}10^{-7}g/mL$, asafetida is toxic for cells and induces cell death. Conclusion: The results of this study indicate that asafetida at low concentrations has a rejuvenating effect on senescent fibroblasts whereas at higher concentrations, it has the opposite effect of facilitating cellular apoptosis and death.

• Molecules and Cells
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• 제39권3호
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• pp.266-279
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• 2016

The mechanism by which 12-O-tetradecanoylphorbol-13-acetate (TPA) bypasses cellular senescence was investigated using human diploid fibroblast (HDF) cell replicative senescence as a model. Upon TPA treatment, protein kinase C (PKC) ${\alpha}$ and $PKC{\beta}1$ exerted differential effects on the nuclear translocation of cytoplasmic pErk1/2, a protein which maintains senescence. $PKC{\alpha}$ accompanied pErk1/2 to the nucleus after freeing it from $PEA-15pS^{104}$ via $PKC{\beta}1$ and then was rapidly ubiquitinated and degraded within the nucleus. Mitogen-activated protein kinase docking motif and kinase activity of $PKC{\alpha}$ were both required for pErk1/2 transport to the nucleus. Repetitive exposure of mouse skin to TPA downregulated $PKC{\alpha}$ expression and increased epidermal and hair follicle cell proliferation. Thus, $PKC{\alpha}$ downregulation is accompanied by in vivo cell proliferation, as evidenced in 7, 12-dimethylbenz(a)anthracene (DMBA)-TPA-mediated carcinogenesis. The ability of TPA to reverse senescence was further demonstrated in old HDF cells using RNA-sequencing analyses in which TPA-induced nuclear $PKC{\alpha}$ degradation freed nuclear pErk1/2 to induce cell proliferation and facilitated the recovery of mitochondrial energy metabolism. Our data indicate that TPA-induced senescence reversal and carcinogenesis promotion share the same molecular pathway. Loss of $PKC{\alpha}$ expression following TPA treatment reduces pErk1/2-activated SP1 biding to the $p21^{WAF1}$ gene promoter, thus preventing senescence onset and overcoming G1/S cell cycle arrest in senescent cells.

• 대한화장품학회지
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• 제41권2호
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• pp.135-141
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• 2015

세포 노쇠화(cell senescence)는 나이 듦에 따른 내인성 노화 및 질병들에서 나타날 수 있는 세포의 노화인자 발현, 세포분열 정지 등의 현상으로 일컬어진다. 피부세포의 경우, 노화 및 외부요인으로 인한 세포 노쇠화가 일어나 세포분열의 정지 및 기능 이상이 관찰되며 이는 피부노화를 가속화시키는 요인이 된다. 본 연구에서는, cordycepin을 이용하여 노화된 피부세포의 세포 노쇠화 억제 및 기능 향상을 유도하여 피부노화 개선의 가능성을 제시하였다. 사람에서 유래한 섬유아세포를 이용하여 세포의 ${\beta}$-galactosidase 활성 세포염색 결과, 많은 계대의 세포에서 발현이 높게 나타남을 알 수 있었다. 항산화 및 항염 효과가 알려진 cordycepin을 많은 계대의 세포에 처리하였을 때 ${\beta}$-galactosidase 활성이 확연히 떨어짐을 확인하였고 무혈청 배지 조건에서 많은 계대 세포의 증식 및 생존율을 높이는 결과를 보였으며 세포 노쇠화와 많은 연관성이 대두되고 있는 미토콘드리아의 기능관련 실험을 진행한 결과, 높은 ROS억제능이 나타났다. 본 연구를 통하여 노화된 사람 피부 섬유아세포에서의 cordycepin의 세포 노화 개선능을 알 수 있었으며, 피부 항노화소재로서의 가능성을 확인하였다.

• Journal of Ginseng Research
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• 제44권2호
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• pp.341-349
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• 2020

Background: The replicative senescence of human dermal fibroblasts (HDFs) is accompanied by growth arrest. In our previous study, the treatment of senescent HDFs with Rg3(S) lowered the intrinsic reactive oxygen species (ROS) levels and reversed cellular senescence by inducing peroxiredoxin-3, an antioxidant enzyme. However, the signaling pathways involved in Rg3(S)-induced senescence reversal in HDFs and the relatedness of the stereoisomer Rg3(R) in corresponding signaling pathways are not known yet. Methods: We performed senescence-associated β-galactosidase and cell cycle assays in Rg3(S)-treated senescent HDFs. The levels of ROS, adenosine triphosphate (ATP), and cyclic adenosine monophosphate (cAMP) as well as the mitochondrial DNA copy number, nicotinamide adenine dinucleotide (NAD)⁺/1,4-dihydronicotinamide adenine dinucleotide (NADH) ratio, and NAD-dependent sirtuins expression were measured and compared among young, old, and Rg3(S)-pretreated old HDFs. Major signaling pathways of phosphatidylinositol 3-kinase/Akt, 5' adenosine monophosphate-activated protein kinase (AMPK), and sirtuin 1/3, including cell cycle regulatory proteins, were examined by immunoblot analysis. Results: Ginsenoside Rg3(S) reversed the replicative senescence of HDFs by restoring the ATP level and NAD⁺/NADH ratio in downregulated senescent HDFs. Rg3(S) recovered directly the cellular levels of ROS and the NAD⁺/NADH ratio in young HDFs inactivated by rotenone. Rg3(S) mainly downregulated phosphatidylinositol 3-kinase/Akt through the inhibition of mTOR by cell cycle regulators like p53/p21 in senescent HDFs, whereas Rg3(R) did not alter the corresponding signaling pathways. Rg3(S)-activated sirtuin 3/PGC1α to stimulate mitochondrial biogenesis. Conclusion: Cellular molecular analysis suggests that Rg3(S) specifically reverses the replicative senescence of HDFs by modulating Akt-mTOR-sirtuin signaling to promote the biogenesis of mitochondria.

• Molecules and Cells
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• 제46권11호
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• pp.655-663
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• 2023

Autophagy dysfunction is associated with human diseases and conditions including neurodegenerative diseases, metabolic issues, and chronic infections. Additionally, the decline in autophagic activity contributes to tissue and organ dysfunction and aging-related diseases. Several factors, such as down-regulation of autophagy components and activators, oxidative damage, microinflammation, and impaired autophagy flux, are linked to autophagy decline. An autophagy flux impairment (AFI) has been implicated in neurological disorders and in certain other pathological conditions. Here, to enhance our understanding of AFI, we conducted a comprehensive literature review of findings derived from two well-studied cellular stress models: glucose deprivation and replicative senescence. Glucose deprivation is a condition in which cells heavily rely on oxidative phosphorylation for ATP generation. Autophagy is activated, but its flux is hindered at the autolysis step, primarily due to an impairment of lysosomal acidity. Cells undergoing replicative senescence also experience AFI, which is also known to be caused by lysosomal acidity failure. Both glucose deprivation and replicative senescence elevate levels of reactive oxygen species (ROS), affecting lysosomal acidification. Mitochondrial alterations play a crucial role in elevating ROS generation and reducing lysosomal acidity, highlighting their association with autophagy dysfunction and disease conditions. This paper delves into the underlying molecular and cellular pathways of AFI in glucose-deprived cells, providing insights into potential strategies for managing AFI that is driven by lysosomal acidity failure. Furthermore, the investigation on the roles of mitochondrial dysfunction sheds light on the potential effectiveness of modulating mitochondrial function to overcome AFI, offering new possibilities for therapeutic interventions.

• Molecules and Cells
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• 제41권5호
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• pp.381-389
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• 2018

ARF is a tumor suppressor protein that has a pivotal role in the prevention of cancer development through regulating cell proliferation, senescence, and apoptosis. As a factor that induces senescence, the role of ARF as a tumor suppressor is closely linked to the p53-MDM2 axis, which is a key process that restrains tumor formation. Thus, many cancer cells either lack a functional ARF or p53, which enables them to evade cell oncogenic stress-mediated cycle arrest, senescence, or apoptosis. In particular, the ARF gene is a frequent target of genetic and epigenetic alterations including promoter hyper-methylation or gene deletion. However, as many cancer cells still express ARF, pathways that negatively modulate transcriptional or post-translational regulation of ARF could be potentially important means for cancer cells to induce cellular proliferation. These recent findings of regulators affecting ARF protein stability along with its low levels in numerous human cancers indicate the significance of an ARF post-translational mechanism in cancers. Novel findings of regulators stimulating or suppressing ARF function would provide new therapeutic targets to manage cancer- and senescence-related diseases. In this review, we present the current knowledge on the regulation and alterations of ARF expression in human cancers, and indicate the importance of regulators of ARF as a prognostic marker and in potential therapeutic strategies.