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54 results on '"Jeon, Myung‐Shin"'

51. Hypoxia induces adipocyte differentiation of adipose-derived stem cells by triggering reactive oxygen species generation.

Author

Kim, Ji Hye, Kim, Seok‐Ho, Song, Seung Yong, Kim, Won‐Serk, Song, Sun U., Yi, TacGhee, Jeon, Myung‐Shin, Chung, Hyung‐Min, Xia, Ying, and Sung, Jong‐Hyuk

Subjects
HYPOXEMIA, CELL differentiation, FAT cells, ADIPOSE tissues, REACTIVE oxygen species, NADPH oxidase, CELL proliferation
Abstract

Generation of reactive oxygen species (ROS) by NADPH oxidase 4 (Nox4) induces the proliferation and migration of adipose-derived stem cells (ASCs). However, the functional role of mitochondrial ROS (mtROS) generation in ASCs is unknown. Therefore, we have investigated whether hypoxia induces the differentiation of ASCs via ROS generation. We also have tried to identify the cellular mechanisms of ROS generation underlying adipocyte differentiation. Hypoxia (2%) and ROS generators, such as antimycin and rotenone, induced adipocyte differentiation, which was attenuated by an ROS scavenger. Although Nox4 generates ROS and regulates proliferation of ASCs, Nox4 inhibition or Nox4 silencing did not inhibit adipocyte differentiation; indeed fluorescence intensity of mito-SOX increased in hypoxia, and treatment with mito-CP, a mtROS scavenger, significantly reduced hypoxia-induced adipocyte differentiation. Phosphorylation of Akt and mTOR was induced by hypoxia, while inhibition of these molecules prevented adipocyte differentiation. Thus hypoxia induces adipocyte differentiation by mtROS generation, and the PI3K/Akt/mTOR pathway is involved. [ABSTRACT FROM AUTHOR]

Published
2014
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52. Constitutive Expression in gal7Mutants of Kluyveromyces lactisIs Due to Internal Production of Galactose as an Inducer of the Gal/Lac Regulon†

Author

Cardinali, Gianluigi, Vollenbroich, Verena, Jeon, Myung-Shin, de Graaf, A. A., and Hollenberg, Cornelis P.

Abstract

The induction process of the galactose regulon has been intensively studied, but until now the nature of the inducer has remained unknown. We have analyzed a ∆gal7mutant of the yeast Kluyveromyces lactis, which lacks the galactotransferase activity and is able to express the genes of the Gal/Lac regulon also in the absence of galactose. We found that this expression is semiconstitutive and undergoes a strong induction during the stationary phase. The gal1-209mutant, which has a reduced kinase activity but retains its positive regulatory function, also shows a constitutive expression of β-galactosidase, suggesting that galactose is the inducer. A gal10 deletion in ∆gal7or gal1-209mutants reduces the expression to under wild-type levels. The presence of the inducer could be demonstrated in both ∆gal7crude extracts and culture medium by means of a bioassay using the induction in gal1-209cells. A mutation in the transporter gene LAC12decreases the level of induction in gal7cells, indicating that galactose is partly released into the medium and then retransported into the cells. Nuclear magnetic resonance analysis of crude extracts from ∆gal7cells revealed the presence of 50 μM galactose. We conclude that galactose is the inducer of the Gal/Lac regulon and is produced via UDP-galactose through a yet-unknown pathway.

Published
1997
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54. Lymphocyte Signal Transduction

Author

Constantine Tsoukas and Constantine Tsoukas

Subjects
Lymphocytes--Congresses, Leucocytes--Receptors--Congresses, Cellular signal transduction--Congresses, Post-translational modification--Congresses, Signal Transduction--physiology--Congresses
Abstract

Signal transduction through leukocyte receptors involves a variety of signaling molecules including kinases, phosphatases, adaptor proteins, small GTPases GTP exchange factors, membrane phospholipids as well as others. These signal transducers, regulated by inter- and intra-molecular interactions, as well as by various post-translational modifications, lead to the activation of transcription factors that mediate cellular differentiation and growth, effector cell functions, and apoptotic cell death. Several investigators from various parts of the world convened at the 3rd Lymphocyte Signal Transduction Workshop in Crete, Greece from May 27 to June 1, 2005 to discuss their most recent findings in leukocyte signaling. This volume represents a collection of topics discussed during the conference.

Published
2006

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