• Journal of Yeungnam Medical Science
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• 제34권1호
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• pp.1-10
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• 2017

The life history of man is summarized as a birth-aging-disease-death. Man eventually ages and dies. How long can humans live? What is aging? Why do we age? Is aging inevitable? Can we rejuvenate? Recent researches on biological aging suggest that humans might overcome aging and rejuvenate. In this paper, we review the biologic characteristics of aging and the latest results of biological aging research, implicating that aging can be controlled, further treated, and that humans can ultimately be rejuvenated.

• Asian Pacific Journal of Cancer Prevention
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• 제16권8호
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• pp.3085-3090
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• 2015

The telomeric end structures of the DNA are known to contain tandem repeats of TTAGGG sequence bound with specialised protein complex called the "shelterin complex". It comprises six proteins, namely TRF1, TRF2, TIN2, POT1, TPP1 and RAP1. All of these assemble together to form a complex with double strand and single strand DNA repeats at the telomere. Such an association contributes to telomere stability and its protection from undesirable DNA damage control-specific responses. However, any alteration in the structure and function of any of these proteins may lead to undesirable DNA damage responses and thus cellular senescence and death. In our review, we throw light on how mutations in the proteins belonging to the shelterin complex may lead to various malfunctions and ultimately have a role in tumorigenesis and cancer progression.

• Molecules and Cells
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• 제38권5호
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• pp.390-395
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• 2015

Degradation of chlorophyll (Chl) by Chl catabolic enzymes (CCEs) causes the loss of green color that typically occurs during senescence of leaves. In addition to CCEs, STAYGREEN1 (SGR1) functions as a key regulator of Chl degradation. Although sgr1 mutants in many plant species exhibit a staygreen phenotype, the biochemical function of the SGR1 protein remains elusive. Many recent studies have examined the physiological and molecular roles of SGR1 and its homologs (SGR2 and SGR-LIKE) in Chl metabolism, finding that these proteins have different roles in different species. In this review, we summarize the recent studies on SGR and discuss the most likely functions of SGR homologs.

• 한국동물번식학회:학술대회논문집
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• 한국동물번식학회 2001년도 발생공학 국제심포지움 및 학술대회 발표자료집
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• pp.3-4
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• 2001

Normal cells proliferate generally a limited number doublings in culture and only rarely have they been shown to overcome cellular senescence and crisis stages, and immortalize spontaneously. I have established a number of non-chemically and non-chemically immortalized embryo fibroblastic (EF) cell lines in continuous cell culture. These include the spontaneously immortalized cell line, DF-1 and several immortal EF cell lines derived from various embryonic tissues. I have previously demonstrated that all of the immortal EF cells established have rapid cell proliferation capacity compared to primary EF cells, presumably due to the deregulation of cell cycle regulators such as p53, E2F-1 and the numerous cyclins. DF-1 cells, in particular, were shown to proliferate more rapidly under normal culture conditions compared to other immortal EF cells, implicating other mechanisms may be important for regulating their growth. The possible mechanism(s) underlying the accelerated growth of DF-1 cells will be addressed in this study. (omitted)

• International Journal of Industrial Entomology and Biomaterials
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• 제43권2호
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• pp.94-98
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• 2021

Reactive oxygen species (ROS) induce a variety of cellular responses, such as proliferation, differentiation, senescence, and apoptosis. Intestinal epithelial cells are continuously exposed to ROS, and excessive generation of ROS severely damages cells via oxidative stress. Pro-inflammatory cytokines may lead to intestinal inflammation and damage by inducing excessive ROS generation. In this study, we showed that papiliocin, an antimicrobial peptide, significantly inhibited ROS production, without affecting cell viability. Moreover, TNF-α and IL-6 expression was decreased in the intestinal epithelial cells. The activity of papiliocin may significantly contribute to preserving the integrity of the intestinal mucosa against oxidative damage and inflammation-related disorders.

• 대한치매학회지
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• 제21권3호
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• pp.83-92
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• 2022

Telomeres are located at the end of chromosomes. They are known to protect chromosomes and prevent cellular senescence. Telomere length shortening has been considered an important marker of aging. Many studies have reported this concept in connection with neurodegenerative disorders. Considering the role of telomeres, it seems that longer telomeres are beneficial while shorter telomeres are detrimental in preventing neurodegenerative disorders. However, several studies have shown that people with longer telomeres might also be vulnerable to neurodegenerative disorders. Before these conflicting results can be explained through large-scale longitudinal clinical studies on the role of telomere length in neurodegenerative disorders, it would be beneficial to simultaneously review these opposing results. Understanding these conflicting results might help us plan future studies to reveal the role of telomere length in neurodegenerative disorders. In this review, these contradictory findings are thoroughly discussed, with the aim to better understand the role of telomere length in neurodegenerative disorders.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2001년도 추계학술발표대회
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• pp.189-192
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• 2001

Polyamine 함량이 증가된 형질전환 식물체들은 $H_2O_2$ 처리에 의해서 야기된 산화적스트레스에 대해 야생형 식물체보다 조직 손상이 월등히 낮았으며 백화와 괴사되는 정도도 훨씬 낮았으며 chlorophyll 양의 손실도 비교적 적은 편이었다. 또한 고염분 스트레스를 처리하면서 야생형보다 비교적 높게 유지되었으며 4달 정도까지 생장이 지속되었지만 야생형 식물체에서는 생장이 거의 정지되어 식물체가 고사하였다. 그 외에 ABA를 처리하여 노화를 유도한 경우 야생형에서 훨씬 빠르게 노화가 일어났으며 형질전환 식물체 잎에서는 노화가 트게 지연되었다. 또한 pH3.0의 potassium phosphate를 처리한 경우에도 야생형의 잎보다 형질전환 식물체 잎에서 갈변등의 세포 손상이 크게 지연되었다. 곰팡이 감염에서도 높은 저항성을 보였으며 항산화효소임 GST와 CAT 유전자 발현이 증가하였다. Ethylene 발현 저해 식물체에서도 스트레스를 처리한 후 ethylene 생합성 효소의 발현이 억제되면서 스트레스 저항성을 나타내었다. 따라서 이러한 스트레스에 의하여 유도되는 노화의 지연현상이 야생형 식물체보다 형질전환 식물체 잎에서 두드러지게 나타나는데 그 기작은 mpolyamine이 이러한 스트레스를 완화시키는데 작용하였기 때문이라고 생각된다.

• Nutritional Sciences
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• 제7권4호
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• pp.189-195
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• 2004

1bis study investigated the antioxidative effect in kidney of senescence-accelerated prone SAMP8 mice with calorie restriction. 4-weeks-old SAMP8 female mice were divided into 4 groups according to the experimental feeding period: for 4, 8, 12 month, and at natural death. Each group was subdivided into 2 groups, with thirteen mice each one, as ad libitum group and as dietary restriction group (60% of ad libitum feeding amount). After feeding for a given period, the mice were sacrificed to get the following results: among the experimental groups, there wereno significant differences in xanthine oxidase (XOD) activity in their kidney tissues. The contents of cytochrome $P_{450}$ decreased in ad libitum group and dietary restriction group by age. The activity of NADPH-cytochrome $P_{450}$ reductase showed a trend similar to cytochrome $P_{450}$. Superoxide radical content increased with age. At the 4th, 8th and 12 months of the experimental period, the activity in the dietary restriction group was less than that of ad libitum group by as much as 17% 14% and 14% respectively. For hydrogen peroxide, the contents were increased in the ad libitum group with age, while no correlation between content and age was observed in the dietary restriction group. In the 8th and 12th months of the experimental period, the were in the dietary restriction group less than that of ad libitum group counterpart as much as 17% and 20o/c, respectively. For the cellular membrane stability of the kidney, no significant correlation with age was observed in either the dietary restriction group or the ad libitum group. However at the 12th month of the experiment, however, the stability in the dietary restriction group was 11 % higher than that in the ad libitum group. In conclusion, with these results obtained from the SAMP8 mouse model, we demonstrate that dietary restriction has the effects of anti-oxidation and anti-senescence in the kidney.

• Molecules and Cells
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• 제40권10호
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• pp.773-786
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• 2017

The loss of green coloration via chlorophyll (Chl) degradation typically occurs during leaf senescence. To date, many Chl catabolic enzymes have been identified and shown to interact with light harvesting complex II to form a Chl degradation complex in senescing chloroplasts; this complex might metabolically channel phototoxic Chl catabolic intermediates to prevent oxidative damage to cells. The Chl catabolic enzyme 7-hydroxymethyl Chl a reductase (HCAR) converts 7-hydroxymethyl Chl a (7-HMC a) to Chl a. The rice (Oryza sativa) genome contains a single HCAR homolog (OsHCAR), but its exact role remains unknown. Here, we show that an oshcar knockout mutant exhibits persistent green leaves during both dark-induced and natural senescence, and accumulates 7-HMC a and pheophorbide a (Pheo a) in green leaf blades. Interestingly, both rice and Arabidopsis hcar mutants exhibit severe cell death at the vegetative stage; this cell death largely occurs in a light intensity-dependent manner. In addition, 7-HMC a treatment led to the generation of singlet oxygen ($^1O_2$) in Arabidopsis and rice protoplasts in the light. Under herbicide-induced oxidative stress conditions, leaf necrosis was more severe in hcar plants than in wild type, and HCAR-overexpressing plants were more tolerant to reactive oxygen species than wild type. Therefore, in addition to functioning in the conversion of 7-HMC a to Chl a in senescent leaves, HCAR may play a critical role in protecting plants from high light-induced damage by preventing the accumulation of 7-HMC a and Pheo a in developing and mature leaves at the vegetative stage.

• Molecules and Cells
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• 제21권1호
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• pp.147-152
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• 2006

Most plant organs develop from meristems. Rice FON1, which is an ortholog of Clv1, regulates stem cell proliferation and organ initiation. The point mutations, fon1-1 and fon1-2, disrupt meristem balance, resulting in alteration of floral organ numbers and the architecture of primary rachis branches. In this study, we identified two knockout alleles, fon1-3 and fon1-4, generated by T-DNA and Tos17 insertion, respectively. Unlike the previously isolated point mutants, the null mutants have alterations not only of the reproductive organs but also of vegetative tissues, producing fewer tillers and secondary rachis branches. The mutant plants are semi-dwarfs due to delayed leaf emergence, and leaf senescence is delayed. SEM analysis showed that the shoot apical meristems of fon1-3 mutants are enlarged. These results indicate that FON1 controls vegetative as well as reproductive development by regulating meristem size.