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Regulation of Actin Cytoskeleton by Rap1 Binding to RacGEF1
Hyemin Mun,전택중 한국분자세포생물학회 2012 Molecules and cells Vol.34 No.1
Rap1 is rapidly and transiently activated in response to chemoattractant stimulation and helps establish cell polarity by locally modulating cytoskeletons. Here, we investigated the mechanisms by which Rap1 controls actin cytoskeletal reorganization in Dictyostelium and found that Rap1 interacts with RacGEF1 in vitro and stimulates F-actin polymerization at the sites where Rap1 is activated upon chemoattractant stimulation. Live cell imaging using GFP-coronin, a reporter for F-actin, demonstrates that cells expressing constitutively active Rap1 (Rap1CA) exhibit a high level of F-actin uniformly distributed at the cortex including the posterior and lateral sides of the chemotaxing cell. Examination of the localization of a PH-domain containing PIP3 reporter, PhdA-GFP, and the activation of Akt/Pkb and other Ras proteins in Rap1CA cells reveals that activated Rap1 has no effect on the production of PIP3 or the activation of Akt/Pkb and Ras proteins in response to chemoattractant stimulation. Rac family proteins are crucial regulators in actin cytoskeletal reorganization. In vitro binding assay using truncated RacGEF1 proteins shows that Rap1 interacts with the DH domain of RacGEF1. Taken together, these results suggest that Rap1-mediated F-actin polymerization probably occurs through the Rac signaling pathway by directly binding to RacGEF1.
Guidelines for Manufacturing and Application of Organoids: Liver
Hye-Ran Moon,Seon Ju Mun,Tae Hun Kim,Hyemin Kim,Dukjin Kang,Suran Kim,Ji Hyun Shin,Dongho Choi,Sun-Ju Ahn,Myung Jin Son Korean Society for Stem Cell Research 2024 International journal of stem cells Vol.17 No.2
Recent amendments to regulatory frameworks have placed a greater emphasis on the utilization of in vitro testing platforms for preclinical drug evaluations and toxicity assessments. This requires advanced tissue models capable of accurately replicating liver functions for drug efficacy and toxicity predictions. Liver organoids, derived from human cell sources, offer promise as a reliable platform for drug evaluation. However, there is a lack of standardized quality evaluation methods, which hinders their regulatory acceptance. This paper proposes comprehensive quality standards tailored for liver organoids, addressing cell source validation, organoid generation, and functional assessment. These guidelines aim to enhance reproducibility and accuracy in toxicity testing, thereby accelerating the adoption of organoids as a reliable alternative or complementary tool to animal testing in drug development. The quality standards include criteria for size, cellular composition, gene expression, and functional assays, thus ensuring a robust hepatotoxicity testing platform.
콩기름 저장 중 휘발성분에 대한 LED와 형광등 광원 조사의 영향
박인선(In-Seon Park),최덕주(Duck-Joo Choi),윤예리(Aye-Ree Youn),이윤정(Youn-Jung Lee),김윤경(Youn-Kyeong Kim),김문호(Mun-Ho Kim),최소례(So-Rye Choi),김기화(Ki Hwa Kim),동혜민(Hyemin Dong),한현정(Hyun Jung Han),노봉수(Bong Soo Noh) 한국식품과학회 2013 한국식품과학회지 Vol.45 No.6
본 연구는 전자코를 이용하여 시판 콩기름의 휘발성분이 파장에 영향을 받는지 알아보고자 암실과 형광등 및 파장이 다른 LED 광원을 PE 용기에 조사하면서 12주 동안 변화되는 휘발성분의 패턴 변화를 분석하였다. 콩기름의 휘발성분의 변화는 저장기간 동안 암실 처리구에서 가장 적고 천천히 일어났으며, 형광등 처리구에서 가장 크고 급격한 변화가 일어나는 것을 보여주었다. 저장 초기인 4주에는 형광등 처리구를 제외한 모든 처리구에서 미세한 변화가 일어났으며, 저장 12주에는 형광등 처리구 다음으로 파란색과 백색 LED 처리구에서 큰 변화를 보여준 반면 초록색 LED 처리구에서는 변화가 적었다. 파란색과 흰색 LED 처리구는 저장 12주째에서 급격한 휘발성분의 변화가 나타났다. 하지만 빨간색과 초록색 LED 조사 시에는 8주째에 급격한 휘발성분이 생성된 것에 비하여, 저장 12주째에는 휘발성분의 변화가 매우 감소하는 것을 보여주었다. 또한 초록색 LED 처리구에서 가장 적은 변화를 보였다. 이러한 결과를 토대로 볼 때 초록색 LED 광원에서 콩기름을 전시 판매하는 것이 바람직하며, 형광등과 파란색, 백색 LED 광원은 바람직하지 못한 것으로 판단된다. 또한, 전시 판매가 아니라면 암실에서 저장하는 것이 가장 바람직할 것으로 예상되는 바이다. Soybean oil was stored in polyethylene for 12 weeks at 20oC. The influence of LED (light emitting diode) irradiation on four different wavelengths and fluorescent light was investigated. The pattern changes of volatile components in soybean oil was analyzed by electronic nose based on mass spectrometer. The obtained data from electronic nose were analyzed by discrimination function analysis. Under fluorescent light, the discriminant function first score (DF1) was significantly moved from positive position to negative one after 4-12 weeks. It means that the volatile compounds related to quality of lipid. It was shown to increase slowly due to green light of LED treatment, while blue and white LED light was influenced significantly as well as fluorescent light irradiation. Selection of LED irradiation would provide to keep good quality of soybean oil under distribution chain system.