Time filter

Source Type

Pohang, South Korea

Lee M.J.,Pusan National University | Kim J.,Pohang University of Science and Technology | Kim J.,Sungkyunkwan University | Kim M.Y.,Pusan National University | And 4 more authors.
Journal of Proteome Research

Human adipose tissue-derived mesenchymal stem cells (hASCs) are useful for regeneration of inflamed or injured tissues. To identify secreted hASC proteins during inflammation, hASCs were exposed to tumor necrosis factor-α (TNF-α) and conditioned media derived from hASCs were analyzed by liquid chromatography coupled with tandem mass spectrometry. We identified 187 individual proteins as secreted proteins (secretome) in hASC-conditioned media; 118 proteins were secreted at higher levels upon TNF-α treatment. The TNF-α-induced secretome included a variety of cytokines and chemokines such as interleukin-6 (IL-6), IL-8, chemokine (C-X-C motif) ligand 6, and monocyte chemotactic protein-1 (MCP-1). TNF-α also increased expression of various proteases including cathepsin L, matrix metalloproteases and protease inhibitors, and induced secretion of long pentraxin 3, a key inflammatory mediator implicated in innate immunity. TNF-α-conditioned media stimulated migration of human monocytes, which play a key role in inflammatory responses. This migration was abrogated by pretreatment with neutralizing anti-IL-6, anti-IL-8, and anti-MCP-1 antibodies, suggesting that IL-6, IL-8, and MCP-1 are involved in migration of monocytes. Taken together, these results suggest that TNF-α-induced secretome may play a pivotal role in inflammatory responses and that shotgun proteomic analysis will be useful for elucidation of the paracrine functions of mesenchymal stem cells. © 2010 American Chemical Society. Source

Kim J.,Pohang University of Science and Technology | Choi Y.S.,Pohang University of Science and Technology | Lim S.,Pohang University of Science and Technology | Yea K.,Sanford Burnham Institute for Medical Research | And 8 more authors.

Adipogenesis is a complex process that is accompanied by a number of molecular events. In this study, a proteomic approach was adopted to identify secretory factors associated with adipogenesis. A label-free shotgun proteomic strategy was implemented to analyze proteins secreted by human adipose stromal vascular fraction cells and differentiated adipocytes. A total of 474 proteins were finally identified and classified according to quantitative changes and statistical significances. Briefly, 177 proteins were significantly upregulated during adipogenesis (Class I), whereas 60 proteins were significantly downregulated (Class II). Changes in the expressions of several proteins were confirmed by quantitative RT-PCR and immunoblotting. One obvious finding based on proteomic data was that the amounts of several extracellular modulators of Wnt and transforming growth factor-β (TGF-β) signaling changed during adipogenesis. The expressions of secreted frizzled-related proteins, dickkopfrelated proteins, and latent TGF-β-binding proteins were found to be altered during adipogenesis, which suggests that they participate in the fine regulation of Wnt and TGF-β signaling. This study provides useful tools and important clues regarding the roles of secretory factors during adipogenic differentiation, and provides information related to obesity and obesity-related metabolic diseases. © 2010 Wiley-VCH Verlag GmbH & Co. KGaA. Source

Yoon J.H.,NovaCell Technology Inc. | Kim J.,NovaCell Technology Inc. | Lee H.,NovaCell Technology Inc. | Kim S.Y.,Chung - Ang University | And 4 more authors.
Biochemical and Biophysical Research Communications

The dermal ECM is synthesized from fibroblasts and is primarily compromised of fibrillar collagen and elastic fibers, which support the mechanical strength and resiliency of skin, respectively. Laminin, a major glycoprotein located in the basement membrane, promotes cell adhesion, cell growth, differentiation, and migration. The laminin tyrosine-isoleucine-glycine-serine-arginine (YIGSR) peptide, corresponding to the 929-933 sequence of the β1 chain, is known to be a functional motif with effects on the inhibition of tumor metastasis, the regulation of sensory axonal response and the inhibition of angiogenesis through high affinity to the 67. kDa laminin receptor. In this study, we identified a novel function of the YIGSR peptide to enhance collagen synthesis in human dermal fibroblasts. To elucidate this novel function regarding collagen synthesis, we treated human dermal fibroblasts with YIGSR peptide in both a time- and dose-dependent manner. According to subsequent experiments, we found that the YIGSR peptide strongly enhanced collagen type 1 synthesis without changing cell proliferation or cellular MMP-1 level. This YIGSR peptide-mediated collagen type 1 synthesis was modulated by FAK inhibitor and MEK inhibitor. This study clearly reveals that YIGSR peptide plays a novel function on the collagen type 1 synthesis of dermal fibroblasts and also suggests that YIGSR is a strong candidate peptide for the treatment of skin aging and wrinkles. © 2012 Elsevier Inc. Source

Yoon J.H.,Pohang University of Science and Technology | Kim J.,NovaCell Technology Inc. | Song P.,Pohang University of Science and Technology | Lee T.G.,NovaCell Technology Inc. | And 2 more authors.
Advances in Biological Regulation

Metabolic tissues, including skeletal muscle, adipose tissue and the digestive system, dynamically secrete various factors depending on the metabolic state, communicate with each other and orchestrate functions to maintain body homeostasis. Skeletal muscle secretes cytokines such as interleukin-6 (IL-6), IL-15, fibroblast growth factor-21 (FGF21) and IL-8. These compounds, myokines, play important roles in biological homeostasis such as energy metabolism, angiogenesis and myogenesis. New technological advances have allowed secretomics - analysis of the secretome - to be performed. The application of highly sensitive mass spectrometry makes qualitative and quantitative analysis of the secretome of skeletal muscle possible. Secretory proteins derived from skeletal muscle cells under various conditions were analyzed, and many important factors were suggested. In-depth studies of the secretome from metabolic cells in various conditions are strongly recommended. This study will provide information on methods of novel communication between metabolic tissues. © 2012 Elsevier Ltd. Source

Do E.K.,Pusan National University | Cheon H.C.,Pusan National University | Jang I.H.,Pusan National University | Choi E.J.,Pusan National University | And 8 more authors.
Stem Cells

Oct4 has been implicated in regulation of pluripotency in embryonic stem cells (ESCs) and reprogramming of somatic cells into induced pluripotent stem cells. However, the molecular mechanisms involved in Oct4-dependent regulation of pluripotency and reprogramming have not been clear. To gain insight into the mechanism of regulation of Oct4-mediated self-renewal of ESCs and reprogramming of somatic cells, we attempted to identify Oct4-binding proteins using affinity purification and mass spectrometry. We identified Reptin, a key component of ATP-dependent chromatin remodeling complexes, as an Oct4-binding protein. Depletion of endogenous Reptin using lentiviral short hairpin RNA (shRNA) led to a decrease in the number and size of alkaline phosphatase-positive colonies of mouse ESCs. In addition, shRNA-mediated silencing of Reptin resulted in decreased expression of pluripotency-specific marker genes, including Oct4, Sox2, Nanog, and SSEA-1. Results of the Oct4 reporter assay showed synergism between Oct4 and Reptin, and depletion of endogenous Reptin abolished Oct4 transcriptional activity. Results of a chromatin immunoprecipitation assay showed the overlapping interaction of Reptin and Oct4 to CR4 in the Oct4 enhancer in ESCs. Knockdown of Reptin using shRNA suppressed the reprogramming of mouse embryonic fibroblasts to induced pluripotent stem cells, whereas overexpression of Reptin resulted in enhanced efficiency of induced pluripotent stem cell generation. These results strongly suggest that Reptin plays a key role in maintaining the pluripotency of ESCs and in establishing the pluripotency during reprogramming of somatic cells by regulation of Oct4-mediated gene regulation. Stem Cells 2014;32:3126-3136 © 2014 AlphaMed Press. Source

Discover hidden collaborations