• BMB Reports
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• 제51권3호
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• pp.157-162
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• 2018

Angiogenesis is a complex, multistep process involving dynamic changes in endothelial cell (EC) shapes and behaviors, especially in specialized cell types such as tip cells (with active filopodial extensions), stalk cells (with less motility) and phalanx cells (with stable junction connections). The Hippo-Yes-associated protein (YAP)/ transcription activator with PDZ binding motif (TAZ) signaling plays a critical role in development, regeneration and organ size by regulating cell-cell contact and actin cytoskeleton dynamics. Recently, with the finding that YAP is expressed in the front edge of the developing retinal vessels, Hippo-YAP/TAZ signaling has emerged as a new pathway for blood vessel development. Intriguingly, the LATS1/2-mediated angiomotin (AMOT) family and YAP/TAZ activities contribute to EC shapes and behaviors by spatiotemporally modulating actin cytoskeleton dynamics and EC junction stability. Herein, we summarize the recent understanding of the role of Hippo-YAP/TAZ signaling in the processes of EC sprouting and junction maturation in angiogenesis.

• BMB Reports
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• 제48권8호
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• pp.429-430
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• 2015

Angiogenesis is a complex process involving dynamic interaction of various cell to cell interactions. Endothelial cell interactions regulated by growth factors, inflammatory cytokines, or hemodynamic stress are critical for balancing vascular quiescence and activation. Yes-associated protein (YAP), an effector of Hippo signaling, is known to play significant roles in maintaining cellular homeostasis. However, its role in endothelial cells for angiogenic regulation remains relatively unexplored. We demonstrated the critical role of YAP in vascular endothelial cells and elucidated the underlying molecular mechanisms involved in angiogenic regulation of YAP. YAP was expressed in active angiogenic regions where endothelial cell junctions were relatively loosened. Consistently, YAP subcellular localization and activity were regulated by VE-cadherin-mediated PI3K/Akt pathway. YAP thereby regulated endothelial sprouting via angiopoietin-2 expression. These results provide an insight into a model of coordinating endothelial junctional stability and angiogenic activation through YAP. [BMB Reports 2015; 48(8): 429-430]

• BMB Reports
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• 제39권2호
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• pp.132-139
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• 2006

Vascular endothelial cadherin (VE-cadherin), which belongs to the classical cadherin family, is localized at adherens junctions exclusively in vascular endothelial cells. Biochemical and biomechanical cues regulate the VE-cadherin adhesive potential by triggering the intracellular signals. VE-cadherin-mediated cell adhesion is required for cell survival and endothelial cell deadhesion is required for vascular development. It is therefore crucial to understand how VE-cadherin-based cell adhesion is controlled. This review summarizes the inter-endothelial cell adhesions and introduces our recent advance in Rap1-regulated VE-cadherin adhesion. A further analysis of the VE-cadherin recycling system will aid the understanding of cell adhesion/deadhesion mechanisms mediated by VE-cadherin in response to extracellular stimuli during development and angiogenesis.

• The Korean Journal of Physiology and Pharmacology
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• 제5권1호
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• pp.1-8
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• 2001

Hyperpolarization of arterial smooth muscle by acetylcholine is considered to be produced by the release of an unidentified chemical substance, an endothelium-derived hyperpolarizing factor (EDHF). Several chemicals have been proposed as the candidate for EDHF. However, none of them fulfil completely the nature and property of EDHF. Ultrastructural observation with electron microscope reveals that in some arteries, gap junctions are formed between endothelial and smooth muscle cells. In small arterioles, injection of gap junction permeable dyes into an endothelial cell results in a distribution of the dye to surrounding cells including smooth muscle cells. These observations allow the speculation that myoendothelial gap junctions may have a functional significance. Simultaneous measurement of the electrical responses in both endothelial and smooth muscle cells using the double patch clamp method demonstrates that these two cell types are indeed electrically coupled, indicating that they behave as a functional syncytium. The EDHF-induced hyperpolarization is produced by an activation of $Ca^{2+}-sensitive\;K^+-channels$ that are inhibited by charybdotoxin and apamin. Agonists that release EDHF increase $[Ca^{2+}]_i$ in endothelial cells but not in smooth muscle cells. Inhibition of gap junctions with chemical agents abolishes the agonist-induced hyperpolarization in smooth muscle cells but not in endothelial cells. All these observations can be explained if EDHF is an electrotonic signal propagating from endothelium to smooth muscle cells through gap junctions.

• 한국응용약물학회:학술대회논문집
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• 한국응용약물학회 2002년도 창립10주년기념 및 국립독성연구원 의약품동등성평가부서 신설기념 국재학술대회:생물학적 동등성과 의약품 개발 전략을 위한 국제심포지움
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• pp.235-235
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• 2002

• The Korean Journal of Physiology and Pharmacology
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• 제11권3호
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• pp.107-112
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• 2007

Gap junction protein, connexin, is expressed in endothelial cells of vessels, glomerulus, and renin secreting cells of the kidney. The purpose of this study was to investigate the role of gap junction in renin secretion and its underlying mechanisms using As 4.1 cell line, a renin-expressing clonal cell line. Renin release was increased proportionately to incubation time. The specific gap junction inhibitor, 18-beta glycyrrhetinic acid (GA) increased renin release in dose-dependent and time-dependent manners. Heptanol and octanol, gap junction blockers, also increased renin release, which were less potent than GA. GA-stimulated renin release was attenuated by pretreatment of the cells with amiloride, nifedipine, ryanodine, and thapsigargin. GA dose-dependently increased intracellular $Ca^{2+}$ concentration, which was attenuated by nifedipine, nimodipine, ryanodine, and thapsigargin. However, RP-cAMP, chelerythrine, tyrphostin A23, or phenylarsine oxide did not induced any significant change in GA-stimulated increase of intracellular $Ca^{2+}$ concentration. These results suggest that gap junction plays an important role on the regulation of renin release and intracellular $Ca^{2+}$ concentration in As 4.1 cells.

• Applied Microscopy
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• 제35권4호
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• pp.55-63
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• 2005

쥐의 뇌로부터 미세혈관에서 분리하고 배양한 내피세포의 특성을 현미경관찰, 면역염색과 전기저항을 측정해 관찰하였다. 미세혈관 내피세포는 배양 후 $5{\sim}6$일 경에 단층을 형성하였으며 특징적으로 소용돌이치는 모양을 나타냈다. 내피세포 단층의 전기저항은 배양 후 5일 경까지 따라 증가하였고 이후로는 감소하였다. 면역형광염색에서 anti-GFAP, anti-GalC, anti-neurofilament 160/200 kD antibody에 대한 면역반응을 거의 찾아볼 수 없었어 별아교세포, 희소돌기아교세포 및 신경세포에 의한 우려할 만한 오염은 배제할 수 있었다. vWF 항원에 대한 면역반응은 내피세포의 세포질에 Weibel-Palade 과립이 전반적으로 퍼져 있었다. 치밀이음부를 구성하는 occludin, ZO-1, ZO-2에 대한 면역반응은 내피세포의 접촉부위에서 매우 특징적으로 나타나고 있었다. 요약하면 쥐의 뇌 미세혈관 내피세포를 분리, 배양하여 형태학적, 조직면역 화학적 방법과 전기저항을 측정하여 내피세포의 특성을 확인하였다. 이 생체외 혈액뇌장벽 모델은 앞으로 진행될 액뇌장벽의 특징을 규명하고자 하는 시험관내 실험에 유용하게 이용될 수 있을 것이다.

• Journal of Ginseng Research
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• 제46권5호
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• pp.700-709
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• 2022

Background: Ginsenoside Rd is a natural compound with promising neuroprotective effects. However, the underlying mechanisms are still not well-understood. In this study, we explored whether ginsenoside Rd exerts protective effects on cerebral endothelial cells after oxygen-glucose deprivation/reoxygenation (OGD/R) treatment and its potential docking proteins related to the underlying regulations. Method: Commercially available primary human brain microvessel endothelial cells (HBMECs) were used for in vitro OGD/R studies. Cell viability, pyroptosis-associated protein expression and tight junction protein degradation were evaluated. Molecular docking proteins were predicted. Subsequent surface plasmon resonance (SPR) technology was utilized for validation. Flow cytometry was performed to quantify caspase-1 positive and PI positive (caspase-1+/PI+) pyroptotic cells. Results: Ginsenoside Rd treatment attenuated OGD/R-induced damage of blood-brain barrier (BBB) integrity in vitro. It suppressed NLRP3 inflammasome activation (increased expression of NLRP3, cleaved caspase-1, IL-1β and GSDMD-N terminal (NT)) and subsequent cellular pyroptosis (caspase-1+/PI + cells). Ginsenoside Rd interacted with SLC5A1 with a high affinity and reduced OGD/R-induced sodium influx and potassium efflux in HBMECs. Inhibiting SLC5A1 using phlorizin suppressed OGD/R-activated NLRP3 inflammasome and pyroptosis in HBMECs. Conclusion: Ginsenoside Rd protects HBMECs from OGD/R-induced injury partially via binding to SLC5A1, reducing OGD/R-induced sodium influx and potassium efflux, thereby alleviating NLRP3 inflammasome activation and pyroptosis.

• Applied Microscopy
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• 제30권1호
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• pp.89-100
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• 2000

아프리카 왕달팽이 (Achatina fulica) 및 산민달팽이(Incilaria fruhstorferi)의 타액을 분비하는 관들을 전자현미경을 통해 관찰한 결과 다음과 같은 결론을 얻었다. Achatina fulica의 소엽내관과 소엽간관은 대부분 원형또는 타원형의 도우넛(dough-nut)형태로서 관을 구성하는 내강세포는 세포의 경계가 불분명하며 세포질은 손가락 마주끼기와 같은 많은 주름들로 구성되어 있었다. 이들의 세포상단에는 미세융모가 잘 발달해 있었다. 반면 Incilaria fruhstorfer의 소엽내관과 소엽간관은 불규칙한 단층원주상피로 구성되어 있고, 전자밀도가 높은 세포질 속에는 다소 불규칙한 구형의 과립들로 가득차 있었다. 세포의 상단에는 미세융모의 발달이 미진하였다. Achatina fulica의 타액관은 내강이 비교적 좁은 긴 관상구조를 하고 있었다. 내강상피세포들은 세포의 경계가 불분명하고, 세포질 속에는 많은 공포와 전자밀도가 낮은 투명과립들로 가득 차 있었고 이들 상피세포의 상단에는 길이가 짧고 가늘은 미세융모가 발달해 있었다. 반면 Incilaria fruhstorfer의 타액관은 Achatiana fulica의 타액관 보다 그 직경이 $65\times250{\mu}m$정도로 더 넓었으며 같은 구조의 내강상피로 구성되어 있었고 상피세포의 상단에는 치밀반과 같은 연접장치가 자주 관찰되는 특징도 보였다. Achatina fulica와 Incilaria fruhstorferi 타액선내 혈관들은 타액선 세포사이에 있는 결합조직에서 주로 관찰되었으며 내피세포들은 대부분 불규칙한 구조이고 전자밀도는 높아서 어둡게 관찰되었다. 이들은 사상족을 내어 포식현상을 보였다.

• Applied Microscopy
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• 제29권1호
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• pp.83-94
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• 1999

미세혈관 수술의 발달로 수지동맥의 재접합술이 성행함에 따라 혈관벽의 구조에 관한 연구들이 활발하지만 수지의 미세동맥과 모세혈관에 관한 연구는 드물다. 이에 저자는 흰쥐 수지의 충양근 안에 있는 미세동맥과 모세혈관의 구조를 전자현미경으로 관찰하여 보고하고자 한다. 1. 흰쥐 충양근 내의 미세동맥 (small arterioles)은 그 직경이 $12\sim20{\mu}m$로 중막이 한 층의 평활근세포로 구성된 종말소동맥 (terminal arteriole) 형태였는데 인체의 종말소동맥$(30\sim35{\mu}m)$에 비해 직경이 작았으며, 모세혈관은 직경이 $5\sim8{\mu}m$로 비슷하였다. 2. 모든 미세동맥 및 모세혈관의 내막을 구성하는 내피세포는 연속형 (continuous type)이었고, 따라서 전체 세포질내에 포음소포(pinocytic vesicles)가 많이 관찰되었다. 3. 모세혈관 주위에서 자주 혈관주위세포(pericytes)가 관찰되었는데 철관주위세포의 긴 들기가 내피세포의 일부를 싸는 경우도 많았으며 이들은 기저판에 의해 둘러싸여 있었다. 4. 내피세포들 사이에는 여러 가지 형태의 접촉이 있었으나 특히 폐쇄띠 (tight junction)를 가장 많이 관찰할 수 있었다. 미세동맥의 내피하층은 기저판 아래에서 매우 불규칙한 양상으로 나타났는데 곳곳에 내피세포와 중막을 구성하는 평활근세포의 막이 꽉 붙어 관찰되었다. 5. 미세동맥의 중막을 구성하는 한 층의 평활근세포의 세포질은 많은 filaments가 있어 균질성으로 보이는 균질성 영역 (homogeneous area)과 mitochondria, 조면내형질망, 골지복합체, polyribosome 등이 관찰되는 핵 주위의 비균질성 영역 (non-homogeneous area)으로 구분되었다. 6. 미세동맥의 외막은 섬유모세포의 아주 가느다란 돌기들로 형성되어 있었으며 군데군데 교원섬유들이 관찰되었다.