• 폴리머
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• 제38권1호
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• pp.24-30
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• 2014

망막색소상피(retinal pigment epithelium, RPE)는 시기능을 유지하는데 중요한 역할을 하여 RPE의 퇴화는 여러 망막변성질병을 유발한다. 현재 이에 대한 효과적인 치료법이 부족하여 세포 이식에 적합한 지지체를 제작하기 위해, 생분해성 고분자인 PLGA와 항염증, 항산화 작용 등의 기능이 있는 헤스페리딘을 이용하여 하이브리드 필름을 제조하였다. ARPE-19를 파종한 후, MTT 분석법을 이용하여 세포 증식률을 확인하고, 세포의 부착 및 세포 형태를 SEM을 통하여 확인하였다. 또한 RPE 세포의 특이적 유전자 발현정도를 확인하기 위하여 RT-PCR을 수행하였고, RPE65의 발현을 확인하기 위해 AEC 면역화학적 염색을 실시하였다. 그 결과, 헤스페리딘/PLGA 필름은 PLGA보다 RPE 세포의 부착, 증식 및 표현형 유지가 우수함을 확인하였고, 이를 통해 헤스페리딘/PLGA 필름의 망막재생을 위한 조직공학적 담체로써 응용 가능성을 확인할 수 있었다.

• BMB Reports
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• 제56권2호
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• pp.84-89
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• 2023

The implications of nutrient starvation due to aging on the degeneration of the retinal pigment epithelium (RPE) is yet to be fully explored. We examined the involvement of AMPK activation in mitochondrial homeostasis and its relationship with the maintenance of a healthy mitochondrial population and epithelial characteristics of RPE cells under nutrient starvation. Nutrient starvation induced mitochondrial senescence, which led to the accumulation of reactive oxygen species (ROS) in RPE cells. As nutrient starvation persisted, RPE cells underwent pathological epithelial-mesenchymal transition (EMT) via the upregulation of TWIST1, a transcription regulator which is activated by ROS-induced NF-κB signaling. Enhanced activation of AMPK with metformin decelerated mitochondrial senescence and EMT progression through mitochondrial biogenesis, primed by activation of PGC1-α. Thus, by facilitating mitochondrial biogenesis, AMPK protects RPE cells from the loss of epithelial integrity due to the accumulation of ROS in senescent mitochondria under nutrient starvation.

• Molecules and Cells
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• 제43권7호
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• pp.632-644
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• 2020

The molecular mechanism underlying autophagy impairment in the retinal pigment epithelium (RPE) in dry age-related macular degeneration (AMD) is not yet clear. Based on the causative role of poly(ADP-ribose) polymerase 1 (PARP1) in RPE necrosis, this study examined whether PARP1 is involved in the autophagy impairment observed during dry AMD pathogenesis. We found that autophagy was downregulated following H₂O₂-induced PARP1 activation in ARPE-19 cells and olaparib, PARP1 inhibitor, preserved the autophagy process upon H₂O₂ exposure in ARPE-19 cells. These findings imply that PARP1 participates in the autophagy impairment upon oxidative stress in ARPE-19 cells. Furthermore, PARP1 inhibited autolysosome formation but did not affect autophagosome formation in H₂O₂-exposed ARPE-19 cells, demonstrating that PARP1 is responsible for impairment of late-stage autophagy in particular. Because PARP1 consumes NAD⁺ while exerting its catalytic activity, we investigated whether PARP1 impedes autophagy mediated by sirtuin1 (SIRT1), which uses NAD⁺ as its cofactor. A NAD⁺ precursor restored autophagy and protected mitochondria in ARPE-19 cells by preserving SIRT1 activity upon H₂O₂. Moreover, olaparib failed to restore autophagy in SIRT1-depleted ARPE-19 cells, indicating that PARP1 inhibits autophagy through SIRT1 inhibition. Next, we further examined whether PARP1-induced autophagy impairment occurs in the retinas of dry AMD model mice. Histological analyses revealed that olaparib treatment protected mouse retinas against sodium iodate (SI) insult, but not in retinas cotreated with SI and wortmannin, an autophagy inhibitor. Collectively, our data demonstrate that PARP1-dependent inhibition of SIRT1 activity impedes autophagic survival of RPE cells, leading to retinal degeneration during dry AMD pathogenesis.

• Applied Microscopy
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• 제27권2호
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• pp.131-144
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• 1997

The present study was carried out to investigate the processes of the ultrastructural differentiation and the acetylcholinesterase (AChE) activities of the developing rat retina. The results are as follows. The retina of fetal rat on the 13th day of gestation showed the early stage of differentiation. Briefly, there appeared dividing chromosomes, the plentiful free ribosomes, and the high ratio of nucleus to cytoplasm. The reaction products by AChE were localized at the membrane of endoplasmic reticulum and on the outer membrane of nucleus. Ultrastructures and AChE activities in the retina of the fetal rats on the 18th day of gestation were similar to those of the prior stages, except the appearence of rough endoplasmic reticulum and Golgi apparatus. According to the ultrastructural observations, the rat retina was still in immature state at birth, but the pigment epithelial cells were fully differentiated, e. g. the increase of melanin granules, the development of mitochondria and Golgi apparatus. The AChE activity was weekly detected. The differentiated retinal layers and the outer segment of photoreceptor cells were observed on the 7th postnatal day. And the pigment epithelium appeared to be fully differentiated. On the 14th postnatal day, rat retina were completely differentiated. In other words, the rat retina was characterized by the prominent outer segments, phagocytosed residues in the pigment epithelium, and the localization of reaction products by AChE in the synapses. In conclusion, the differentiation of rat retina is charaterized by the changes of cell shape, the increase of retinal layers, and the alterations of AChE activities. It seems that rat retina is to be functional from 2 weeks of birth onward, coinciding with the eye opening of the juvenile rats.

• BMB Reports
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• 제53권5호
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• pp.284-289
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• 2020

Tamoxifen, a nonsteroidal estrogen receptor (ER) antagonist, is used routinely as a chemotherapeutic agent for ER-positive breast cancer. However, it is also causes side effects, including retinotoxicity. The retinal pigment epithelium (RPE) has been recognized as the primary target of tamoxifen-induced retinotoxicity. The RPE plays an essential physiological role in the normal functioning of the retina. Nonetheless, potential therapeutic agents to prevent tamoxifen-induced retinotoxicity in breast cancer patients have not been investigated. Here, we evaluated the action mechanisms of sulfasalazine against tamoxifen-induced RPE cell death. Tamoxifen induced reactive oxygen species (ROS)-mediated autophagic cell death and caspase-1-mediated pyroptosis in RPE cells. However, sulfasalazine reduced tamoxifen-induced total ROS and ROS-mediated autophagic RPE cell death. Also, mRNA levels of tamoxifen-induced pyroptosis-related genes, IL-1β, NLRP3, and procaspase-1, also decreased in the presence of sulfasalazine in RPE cells. Additionally, the mRNA levels of tamoxifen-induced AMD-related genes, such as complement factor I (CFI), complement factor H (CFH), apolipoprotein E (APOE), apolipoprotein J (APOJ), toll-like receptor 2 (TLR2) and toll-like receptor 4 (TLR4), were downregulated in RPE cells. Together, these data provide novel insight into the therapeutic effects of sulfasalazine against tamoxifen-induced RPE cell death.

• Molecules and Cells
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• 제46권7호
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• pp.420-429
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• 2023

Age-related macular degeneration (AMD) is one of the leading causes of blindness in elderly individuals. However, the currently used intravitreal injections of anti-vascular endothelial growth factor are invasive, and repetitive injections are also accompanied by a risk of intraocular infection. The pathogenic mechanism of AMD is still not completely understood, but a multifactorial mechanism that combines genetic predisposition and environmental factors, including cellular senescence, has been suggested. Cellular senescence refers to the accumulation of cells that stop dividing due to the presence of free radicals and DNA damage. Characteristics of senescent cells include nuclear hypertrophy, increased levels of cell cycle inhibitors such as p16 and p21, and resistance to apoptosis. Senolytic drugs remove senescent cells by targeting the main characteristics of these cells. One of the senolytic drugs, ABT-263, which inhibits the antiapoptotic functions of Bcl-2 and Bcl-xL, may be a new treatment for AMD patients because it targets senescent retinal pigment epithelium (RPE) cells. We proved that it selectively kills doxorubicin (Dox)-induced senescent ARPE-19 cells by activating apoptosis. By removing senescent cells, the expression of inflammatory cytokines was reduced, and the proliferation of the remaining cells was increased. When ABT-263 was orally administered to the mouse model of senescent RPE cells induced by Dox, we confirmed that senescent RPE cells were selectively removed and retinal degeneration was alleviated. Therefore, we suggest that ABT-263, which removes senescent RPE cells through its senolytic effect, has the potential to be the first orally administered senolytic drug for the treatment of AMD.

• Molecules and Cells
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• 제46권11호
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• pp.675-687
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• 2023

Accumulation of pathogenic amyloid-β disrupts the tight junction of retinal pigment epithelium (RPE), one of its senescence-like structural alterations. In the clearance of amyloid-β, the autophagy-lysosome pathway plays the crucial role. In this context, mammalian target of rapamycin (mTOR) inhibits the process of autophagy and lysosomal degradation, acting as a potential therapeutic target for age-associated disorders. However, efficacy of targeting mTOR to treat age-related macular degeneration remains largely elusive. Here, we validated the therapeutic efficacy of the mTOR inhibitors, Torin and PP242, in clearing amyloid-β by inducing the autophagy-lysosome pathway in a mouse model with pathogenic amyloid-β with tight junction disruption of RPE, which is evident in dry age-related macular degeneration. High concentration of amyloid-β oligomers induced autophagy-lysosome pathway impairment accompanied by the accumulation of p62 and decreased lysosomal activity in RPE cells. However, Torin and PP242 treatment restored the lysosomal activity via activation of LAMP2 and facilitated the clearance of amyloid-β in vitro and in vivo. Furthermore, clearance of amyloid-β by Torin and PP242 ameliorated the tight junction disruption of RPE in vivo. Overall, our findings suggest mTOR inhibition as a new therapeutic strategy for the restoration of tight junctions in age-related macular degeneration.

• 대한안과학회지
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• 제59권12호
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• pp.1190-1194
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• 2018

목적: 단안에 국소적으로 발생한 색소정맥옆망막맥락막 위축(pigmented paravenous retinochoroidal atrophy) 1예를 경험하여 이를 보고하고자 한다. 증례요약: 46세 여자 환자가 건강검진상에서 발견된 우안 망막 이상 소견으로 내원하였다. 나안시력은 양안 모두 1.0이었다. 세극등현미경으로 시행한 전안부 검사상 특이 이상 소견은 관찰되지 않았다. 안저검사상 우안의 상측 망막정맥을 따라 국소적으로 분포된 뼈 조각 모양의 색소침착이 동반된 망막맥락막위축 소견이 관찰되었다. 안저자가형광상 우안의 망막맥락막위축의 경계에서 다소 과형광을 보이면서 병변의 대부분은 저형광 소견을 보였다. 빛간섭단층촬영상 해당 병변은 망막색소상피층의 위축 및 뭉침이 혼재되어 있었고, 맥락막층에서 맥락막모세혈관층이 얇아진 소견을 보였다. 형광안저촬영상 병변 내 창문비침 및 형광차단이 혼재되어 관찰되었으며 이는 망막색소상피층의 위축 및 뭉침 부위와 일치하였다. 결론: 단안에 국소적으로 발생한 색소정맥옆망막맥락막 위축 1예를 경험하여 이를 국내 최초로 보고하는 바이다.

• Journal of Photoscience
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• 제7권4호
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• pp.161-167
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• 2000

Temperature-dependent electroretinogram responses were investigated in the dark adapted bullfrog eyes within the physiological temperature range 0-40$\^{C}$. In hypothermic process(25→0→25$\^{C}$), the amplitude of b-and c-wave decreased with lowering the temperature again. Both b-wave amplitude and threshold responses were maximal around 15$\^{C}$ during the temperature increment. Upon warming to room temperature again (25$\^{C}$), the b-wave amplitude was approximately doubled as compared to that of control without temperature changes. During the hyperthermic process (25→40→25$\^{C}$), however, the responses decreased with warming, and the wave amplitude failed to recover by cooling to 25$\^{C}$ again. As describe above, the recoveries of ERG in both processes show the striking difference. The hypothermia induces the amplification of the b-wave, that is, enhances the retinal function with the temperature recovery toward room temperature. While the hypertherima produces the decrease of the b-wave even though recovered to room temperature, which indicates an irreversible retina. The morphological alteration is shown both hypothermic and hyperthermic process, such as an appearance of large vacuoles and degenerating outer segments, more intense in hyperthermia, similar to light induced damage.

• 한국어류학회지
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• 제22권2호
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• pp.96-104
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• 2010

멸조위기종인 묵납자루 Acheilognathus signifer의 종복원을 위한 인공수정을 실시하는 과정에서눈과 피부의 색소발현이 결여된 백색증 개체가 출현하였다. 정상 묵납자루와 백색증 개체간 색소발현과 형태의 차이여부를 알아보기 위하여 몸통, 지느러미 눈 등 총 10개 부위에 대한 조직학적 검사를 실시하였다. 그 결과 정상 묵납자루의 경우, 멜라닌세포는 빛에 쉽게 노출되는 등부위와 상미병부, 맥락막-망막색소상피층 및 홍채에서 다량으로 분포하였다. 반면에 백색증 개체에서는 멜라닌세포가 등 부위와 등지느러미, 그리고 꼬리지느러미에서 아주 소량으로 분포하고 있었으며 눈의 맥락막-망막색소상피층 및 홍채에서는 색소결핍 현상이 뚜렷하게 관찰되었다.