• 환경생물
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• 제27권1호
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• pp.66-72
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• 2009

당뇨망막병증은 서구에서 성인들의 실명을 일으키는 원인이다. 당뇨병이 있을 때 고혈당증은 여러 세포 형태에서 세포자연사를 유도하지만 그 기작은 명확하게 밝혀지지 않았다. 본 연구의 목적은 인간망막 내피세포에서 고혈당 포도당이 세포자연사에 미치는 영향에 대하여 알아보았다. 망막 내피세포는 5, 25, 50 mM 포도당이 포함된 IMDM배지에서 37$^{\circ}C$, 5% CO$_2$조정된 항온기에서 24, 36, 48시간 동안 배양하였다. 여러 농도의 포도당을 처리한 인간망막 내피세포 형태의 특징은 위상차현미경으로 관찰하였고, 세포의 생존은 MTT assay를 통해 산정하였다. 고농도 포도당에서 활성산소종인 세포 내의 H$_2$O$_2$는 FOX II assay와 caspase-3 assay에 의한 세포자연사를 통해 측정하였다. 고농도의 포도당을 처리한 세포에서의 DNA분절화는 아가펄스 겔 전기영동을 통해 관찰하였다. 25, 50mM 포도당을 포함한 배양액에 48시간 동안 배양한 세포는 형태가 변하고. 세포자연사에 의해 유도된 DNA 분절화를 관찰 할 수 있었다. 25, 50 mM의 포도당에서 배양한 세포와 5 mM 포도당에서 24, 36, 48 시간 배양한 세포와 비교했을 때 25, 50 mM에서 죽은 세포의 수가 더 많았다. 또한 과산화수소의 양과 caspase-3의 활성은 고농도 포도당을 처리한 세포에서 증가하였다. 결론적으로 고농도 포도당이 배양된 인간망막 내피세포에서 세포자연사를 유도하는 것을 증명하였고, 고혈당증의 유도로 caspase 활성에 의존적인 세포자연사는 증가하였다. 고농도의 포도당이 처리된 세포에서 활성산소종 유발과 caspase-3 활성간의 관계는 아직 조사되지않았다.

• The Korean Journal of Physiology and Pharmacology
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• 제2권1호
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• pp.21-30
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• 1998

The effects of GABA and glutamate on the horizontal cells were explored by an intracellular recording method to discern the mechanisms of receptive field formation by chemical coupling in the catfish outer retina. The results suggest that the horizontal cells of the catfish retina might use GABA as their transmitters and that the GABAergic system contributes to the formation of receptive fields of the horizontal cells. GABAC receptors may be involved in a chemical coupling between horizontal cells and concerned with the depolarizing actions by GABA on horizontal cells in the catfish retina. Since the chloride equilibrium potential is more positive than the dark membrane potential in horizontal cells, GABA released from a horizontal cell may depolarize the neighboring horizontal cells. Thus a chemical coupling between horizontal cells may be formed. $GABA_A$ receptors also may be involved in the negative feedback mechanism between photoreceptor and horizontal cell. And glutamate may be involved in connecting positive and negative feedback systems since it potentiated the GABA's actions. Therefore, it is presumed that large receptive fields in the catfish retina are formed not only by electrical coupling but also by chemical coupling between horizontal cells. And information travels laterally by pathways involving both electrical coupling composed of gap junctions and chemical coupling in the retinal network.

• Journal of Korean Neurosurgical Society
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• 제65권3호
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• pp.370-379
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• 2022

Abusive head trauma (AHT) is the most severe form of physical abuse in children. Such injury involves traumatic damage to the head and/or spine of infants and young children. The term AHT was introduced to include a wider range of injury mechanisms, such as intentional direct blow, throw, and even penetrating trauma by perpetuator(s). Currently, it is recommended to replace the former term, shaken baby syndrome, which implicates shaking as the only mechanism, with AHT to include diverse clinical and radiological manifestations. The consequences of AHT cause devastating medical, social and financial burdens on families, communities, and victims. The potential harm of AHT to the developing brain and spinal cord of the victims is tremendous. Many studies have reported that the adverse effects of AHT are various and serious, such as blindness, mental retardation, physical limitation of daily activities and even psychological problems. Therefore, appropriate vigilance for the early recognition and diagnosis of AHT is highly recommended to stop and prevent further injuries. The aim of this review is to summarize the relevant evidence concerning the early recognition and diagnosis of AHT. To recognize this severe type of child abuse early, all health care providers maintain a high index of suspicion and vigilance. Such suspicion can be initiated with careful and thorough history taking and physical examinations. Previously developed clinical prediction rules can be helpful for decision-making regarding starting an investigation when considering meaningful findings. Even the combination of biochemical markers may be useful to predict AHT. For a more confirmative evaluation, neuroradiological imaging is required to find AHT-specific findings. Moreover, timely consultation with ophthalmologists is needed to find a very specific finding, retinal hemorrhage.

• 한국발생생물학회지:발생과생식
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• 제16권4호
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• pp.301-307
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• 2012

Olive flounder Paralichthys olivaceus is one of the most widely cultured fish species in Korea. Although olive flounder receive attention from aquaculture and fisheries and extensive research has been conducted eye morphological change in metamorphosis, but little information was known to molecular mechanism and gene expression of eye development- related genes during the early part of eye formation period. For the reason of eyesight is the most important sense in flounder larvae to search prey, the screening and identification of expressed genes in the eye will provide useful insight into the molecular regulation mechanism of eye development in olive flounder. Through the search of an olive flounder DNA database of expressed sequence tags (EST), we found a partial sequence that was similar to crystallin beta A1 and gamma S. Microscopic observation of retinal formation correspond with the time of expression of the crystallin beta A1 and gamma S gene in the developmental stage, these result suggesting that beta A1 and gamma S play a vital role in the remodeling of the retina during eye development. The expression of crystallin beta A1 and gamma S were obviously strong in eye at all tested developing stage, it is also hypothesized that crystallin acts as a molecular chaperone to prevent protein aggregation during maturation and aging in the eye.

• BMB Reports
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• 제49권5호
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• pp.245-246
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• 2016

The level and activity of critical regulatory proteins in cells are tightly controlled by several tiers of post-translational modifications. HIF-1α is maintained at low levels under normoxia conditions by the collaboration between PHD proteins and the VHL-containing E3 ubiquitin ligase complex. We recently identified a new physiologically relevant mechanism that regulates HIF-1α stability in the nucleus in response to cellular oxygen levels. This mechanism is based on the collaboration between the SET7/9 methyltransferase and the LSD1 demethylase. SET7/9 adds a methyl group to HIF-1α, which triggers degradation of the protein by the ubiquitin-proteasome system, whereas LSD1 removes the methyl group, leading to stabilization of HIF-1α under hypoxia conditions. In cells from knock-in mice with a mutation preventing HIF-1α methylation (Hif1α^KA/KA), HIF-1α levels were increased in both normoxic and hypoxic conditions. Hif1α^KA/KA knock-in mice displayed increased hematological parameters, such as red blood cell count and hemoglobin concentration. They also displayed pathological phenotypes; retinal and tumor-associated angiogenesis as well as tumor growth were increased in Hif1α^KA/KA knock-in mice. Certain human cancer cells exhibit mutations that cause defects in HIF-1α methylation. In summary, this newly identified methylation-based regulation of HIF-1α stability constitutes another layer of regulation that is independent of previously identified mechanisms.

• Parasites, Hosts and Diseases
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• 제56권2호
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• pp.135-145
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• 2018

Due to the critical location and physiological activities of the retinal pigment epithelial (RPE) cell, it is constantly subjected to contact with various infectious agents and inflammatory mediators. However, little is known about the signaling events in RPE involved in Toxoplasma gondii infection and development. The aim of the study is to screen the host mRNA transcriptional change of 3 inflammation-related gene categories, PI3K/Akt pathway regulatory components, blood vessel development factors and ROS regulators, to prove that PI3K/Akt or mTOR signaling pathway play an essential role in regulating the selected inflammation-related genes. The selected genes include PH domain and leucine- rich-repeat protein phosphatases (PHLPP), casein kinase2 (CK2), vascular endothelial growth factor (VEGF), pigment epithelium-derived factor (PEDF), glutamate-cysteine ligase (GCL), glutathione S-transferase (GST), and NAD(P)H: quinone oxidoreductase (NQO1). Using reverse transcription polymerase chain reaction (RT-PCR) and quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR), we found that T. gondii up-regulates PHLPP2, $CK2{\beta}$, VEGF, GCL, GST and NQO1 gene expression levels, but down-regulates PHLPP1 and PEDF mRNA transcription levels. PI3K inhibition and mTOR inhibition by specific inhibitors showed that most of these host gene expression patterns were due to activation of PI3K/Akt or mTOR pathways with some exceptional cases. Taken together, our results reveal a new molecular mechanism of these gene expression change dependent on PI3K/Akt or mTOR pathways and highlight more systematical insight of how an intracellular T. gondii can manipulate host genes to avoid host defense.

• 한국식품영양과학회지
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• 제46권2호
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• pp.161-168
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• 2017

본 연구에서는 산화적 스트레스로 유도한 시신경 세포사멸에 대한 차조기 물 추출물(PFE)의 효과를 확인하였다. Staurosporine으로 분화된 ssdRGC-5 세포에 buthionine과 glutamate(B/G)로 산화적 스트레스를 유도하였으며, LDH release assay, MTT reduction assay를 통하여 PFE가 농도 의존적으로 B/G에 의한 세포사멸을 억제함을 관찰하였다. 세포사멸의 기전을 연구하기 위해 caspase 활성, 세포 내 ROS 생성량, 세포고사 관련 단백질 발현을 관찰한 결과, B/G에 의해 증가한 ROS 생성량, caspase 활성을 PFE가 억제하였고, 세포질로 방출된 cytochrome c와 미토콘드리아로 이동한 Bax도 감소함을 확인하였다. 이상의 결과로부터 차조기는 산화적 스트레스로 유도된 시신경 세포사멸 과정에서 항산화 효과와 미토콘드리아성 세포사멸을 완화함으로써 세포 보호 작용을 나타냄을 확인하였다.

• Journal of Photoscience
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• 제9권2호
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• pp.41-43
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• 2002

In photoreceptor cells, light activates visual pigments consisting of a chromophore (retinal) and a protein moiety (opsin). Activated visual pigments trigger an enzymatic cascade, called phototransduction cascade, in which more than ten phototransduction proteins are participating. Two types of vertebrate photoreceptor cells, rods and cones, play roles in twilight and daylight vision, respectively. Cones are further classified into several subtypes based on their morphology and spectral sensitivity. Though the diversities of vertebrate photoreceptor cells are crucial for color discrimination and detection of light over a wider range of intensities, the molecular mechanism to characterize the photoreceptor types remains unclear. We investigated the amino acid sequences of about 50 vertebrate opsins, and found that these sequences can be classified into five fundamental subfamilies. Clear relationships were found between these subfamilies and their characteristic spectral sensitivities. In addition to opsins, we studied other phototransduction proteins. The amino acid sequences of phototransduction proteins can be classified into a few subfamilies. Even though their spectral sensitivity is considerably different, cones fundamentally share the phototransduction protein isoforms which are different from those found in rods. It is suggested that the difference in phototransduction proteins between rods and cones is responsible for their sensitivity to light. Isoforms and their selective expression may characterize individual photoreceptor cells, thus providing us with physiological functions such as color vision and daylight/twilight visions.

• Molecules and Cells
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• 제38권2호
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• pp.105-111
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• 2015

The beta2-adrenergic receptor (${\beta}2AR$) belongs to the G protein coupled receptor (GPCR) family, which is the largest family of cell surface receptors in humans. Extra attention has been focused on the human GPCRs because they have been studied as important protein targets for pharmaceutical drug development. In fact, approximately 40% of marketed drugs directly work on GPCRs. GPCRs respond to various extracellular stimuli, such as sensory signals, neurotransmitters, chemokines, and hormones, to induce structural changes at the cytoplasmic surface, activating downstream signaling pathways, primarily through interactions with heterotrimeric G proteins or through G-protein independent pathways, such as arrestin. Most GPCRs, except for rhodhopsin, which contains covalently linked 11 cis-retinal, bind to diffusible ligands, having various conformational states between inactive and active structures. The first human GPCR structure was determined using an inverse agonist bound ${\beta}2AR$ in 2007 and since then, more than 20 distinct GPCR structures have been solved. However, most GPCR structures were solved as inactive forms, and an agonist bound fully active structure is still hard to obtain. In a structural point of view, ${\beta}2AR$ is relatively well studied since its fully active structure as a complex with G protein as well as several inactive structures are available. The structural comparison of inactive and active states gives an important clue in understanding the activation mechanism of ${\beta}2AR$. In this review, structural features of inactive and active states of ${\beta}2AR$, the interaction of ${\beta}2AR$ with heterotrimeric G protein, and the comparison with ${\beta}1AR$ will be discussed.

• The Korean Journal of Physiology and Pharmacology
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• 제13권2호
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• pp.91-97
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• 2009

The tubby mouse is characterized by progressive retinal and cochlear degeneration and late-onset obesity. These phenotypes are caused by a loss-of-function mutation in the tub gene and are shared with several human syndromes, suggesting the importance of tubby protein in central nervous system (CNS) functioning. Although evidence suggests that tubby may act as a transcription factor mediating G-protein coupled receptor (GPCR) signaling, any downstream gene regulated by tubby has yet to be identified. To explore potential target genes of tubby with region-specific transcription patterns in the brain, we performed a microarray analysis using the cerebral cortex and hypothalamus of tubby mice. We also validated the changes of gene expression level observed with the microarray analysis using real-time RT-PCR. We found that expression of erythroid differentiation factor 1 (Erdrl) and caspase 1 (Casp1) increased, while p21-activated kinase 1 (Pak1) and cholecystokinin 2 receptor (Cck2r) expression decreased in the cerebral cortex of tubby mice. In the hypothalamic region, Casp 1 was up-regulated and $\mu$-crystallin (CRYM) was down-regulated. Based on the reported functions of the differentially expressed genes, these individual or grouped genes may account for the phenotype of tubby mice. We discussed how altered expression of genes in tubby mice might be understood as the underlying mechanism behind tubby phenotypes.