Diatech Korea Co.

Seoul, South Korea

Diatech Korea Co.

Seoul, South Korea
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Jeon A.,Sogang University | Lee J.H.,Sogang University | Kwon H.S.,Sogang University | Park H.S.,Diatech Korea Co. | And 2 more authors.
Mass Spectrometry Letters | Year: 2013

In the present study, we report that the charge-directed (assisted) peptide dissociation products, such as b- and y-type peptide backbone fragments, were the major products in MS/MS and MS3 applications of some o-TEMPO-Bz-C(O)-peptide ions, while radical-driven dissociation products, such as a/x and c/z-type fragments, were previously shown to be the major products in the free radical initiated peptide sequencing mass spectrometry (FRIPS MS). Those o-TEMPO-Bz-C(O)-peptides share a common feature in their sequences, that is, the peptides do not include an arginine residue that has the highest proton affinity among free amino acids. The appearance of b- and y-type fragments as major products in FRIPS MS can be understood in terms of the so-called "mobile-proton model". When the proton is highly mobilized by the absence of arginine, the chare-directed peptide dissociation pathways appear to be more competitive than the radical-driven dissociation pathways, in our FRIPS experiments.


Woo D.-H.,Korea University | Kim S.-K.,Korea University | Kim S.-K.,U.S. National Institutes of Health | Lim H.-J.,Korea University | And 17 more authors.
Gastroenterology | Year: 2012

Background & Aims: Many studies of embryonic stem cells have investigated direct cell replacement of damaged tissues, but little is known about how donor cellderived signals affect host tissue regeneration. We investigated the direct and indirect roles of human embryonic stem cellderived cells in liver repair in mice. Methods: To promote the initial differentiation of human embryonic stem cells into mesendoderm, we activated the β-catenin signaling pathway with lithium; cells were then further differentiated into hepatocyte-like cells. The differentiated cells were purified by indocyanine green staining and laser microdissection and characterized by immunostaining, polymerase chain reaction, biochemical function, electron microscopy, and transplantation analyses. To investigate indirect effects of these cells, secreted proteins (secretomes) were analyzed by a label-free quantitative mass spectrometry. Carbon tetrachloride was used to induce acute liver injury in mice; cells or secreted proteins were administered by intrasplenic or intraperitoneal injection, respectively. Results: The differentiated hepatocyte-like cells had multiple features of normal hepatocytes, engrafted efficiently into mice, and continued to have hepatic features; they promoted proliferation of host hepatocytes and revascularization of injured host liver tissues. Proteomic analysis identified proteins secreted from these cells that might promote host tissue repair. Injection of the secreted proteins into injured livers of mice promoted significant amounts of tissue regeneration without cell grafts. Conclusions: Hepatocyte-like cells derived from human embryonic stem cells contribute to recovery of injured liver tissues in mice, not only by cell replacement but also by delivering trophic factors that support endogenous liver regeneration. © 2012 AGA Institute.


Jayabalan A.K.,Chosun University | Sanchez A.,University of South Florida | Park R.Y.,Chosun University | Yoon S.P.,Jeju National University | And 5 more authors.
Nature Communications | Year: 2016

Stress granules (SGs) harbour translationally stalled messenger ribonucleoproteins and play important roles in regulating gene expression and cell fate. Here we show that neddylation promotes SG assembly in response to arsenite-induced oxidative stress. Inhibition or depletion of key components of the neddylation machinery concomitantly inhibits stress-induced polysome disassembly and SG assembly. Affinity purification and subsequent mass-spectrometric analysis of Nedd8-conjugated proteins from translationally stalled ribosomal fractions identified ribosomal proteins, translation factors and RNA-binding proteins (RBPs), including SRSF3, a previously known SG regulator. We show that SRSF3 is selectively neddylated at Lys85 in response to arsenite. A non-neddylatable SRSF3 (K85R) mutant do not prevent arsenite-induced polysome disassembly, but fails to support the SG assembly, suggesting that the neddylation pathway plays an important role in SG assembly.


Kim J.-H.,Seoul National University | Choi S.-Y.,Seoul National University | Kang B.-H.,Seoul National University | Lee S.-M.,Seoul National University | And 6 more authors.
Biochemical and Biophysical Research Communications | Year: 2013

CtBP is a transcriptional repressor which plays a significant role in the regulation of cell proliferation and tumor progression. It was reported that glucose withdrawal causes induction of Bax due to the dissociation of CtBP from the Bax promoter. However, the precise mechanism involved in the regulation of CtBP still remains unclear. In this study, we found that an activated AMP-activated protein kinase (AMPK) phosphorylates CtBP1 on Ser-158 upon metabolic stresses. Moreover, AMPK-mediated phosphorylation of CtBP1 (S158) attenuates the repressive function of CtBP1. We also confirmed that triggering activation of AMPK by various factors resulted in an increase of Bax gene expression. These findings provide connections of AMPK with CtBP1-mediated regulation of Bax expression for cell death under metabolic stresses. © 2012 Elsevier Inc.


Seo K.-S.,Chungnam National University | Park J.-H.,Chungnam National University | Heo J.-Y.,Chungnam National University | Jing K.,Chungnam National University | And 11 more authors.
Oncogene | Year: 2015

Hypoxia-inducible factor-1α (HIF-1α) is a transcription factor that has a central role in the regulation of tumour metabolism under hypoxic conditions. HIF-1α stimulates glycolytic energy production and promotes tumour growth. Sirtuins are NAD(+)-dependent protein deacetylases that regulate cellular metabolism in response to stress; however, their involvement in the hypoxic response remains unclear. In this study, it is shown that SIRT2-mediated deacetylation of HIF-1α regulates its stability in tumour cells. SIRT2 overexpression destabilized HIF-1α under hypoxic conditions, whereas HIF-1α protein levels were high in SIRT2-deficient cells. SIRT2 directly interacted with HIF-1α and deacetylated Lys709 of HIF-1α. Deacetylation of HIF-1α by SIRT2 resulted in increased binding affinity for prolyl hydroxylase 2, a key regulator of HIF-1α stability, and increased HIF-1α hydroxylation and ubiquitination. Moreover, a pharmacological agent that increased the intracellular NAD(+)/NADH ratio led to the degradation of HIF-1α by increasing SIRT2-mediated deacetylation and subsequent hydroxylation. These findings suggest that SIRT2-mediated HIF-1α deacetylation is critical for the destablization of HIF-1α and the hypoxic response of tumour cells.


Seo K.-S.,Chungnam National University | Park J.-H.,Chungnam National University | Heo J.-Y.,Chungnam National University | Jing K.,Chungnam National University | And 11 more authors.
Oncogene | Year: 2014

Hypoxia-inducible factor-1α (HIF-1α) is a transcription factor that has a central role in the regulation of tumour metabolism under hypoxic conditions. HIF-1α stimulates glycolytic energy production and promotes tumour growth. Sirtuins are NAD+-dependent protein deacetylases that regulate cellular metabolism in response to stress; however, their involvement in the hypoxic response remains unclear. In this study, it is shown that SIRT2-mediated deacetylation of HIF-1α regulates its stability in tumour cells. SIRT2 overexpression destabilized HIF-1α under hypoxic conditions, whereas HIF-1α protein levels were high in SIRT2-deficient cells. SIRT2 directly interacted with HIF-1α and deacetylated Lys709 of HIF-1α. Deacetylation of HIF-1α by SIRT2 resulted in increased binding affinity for prolyl hydroxylase 2, a key regulator of HIF-1α stability, and increased HIF-1α hydroxylation and ubiquitination. Moreover, a pharmacological agent that increased the intracellular NAD+/NADH ratio led to the degradation of HIF-1α by increasing SIRT2-mediated deacetylation and subsequent hydroxylation. These findings suggest that SIRT2-mediated HIF-1α deacetylation is critical for the destablization of HIF-1α and the hypoxic response of tumour cells.Oncogene advance online publication, 31 March 2014; doi:10.1038/onc.2014.76.


Kang G.-Y.,Diatech Korea Co. | Bang J.Y.,Diatech Korea Co. | Choi A.J.,Konkuk University | Yoon J.,Konkuk University | And 8 more authors.
Journal of Proteome Research | Year: 2014

Age-related macular degeneration (AMD) describes the progressive degeneration of the retinal pigment epithelium (RPE), retina, and choriocapillaris and is the leading cause of blindness in people over 50. The molecular mechanisms underlying this multifactorial disease remain largely unknown. To uncover novel secretory biomarkers related to the pathogenesis of AMD, we adopted an integrated approach to compare the proteins identified in the conditioned medium (CM) of cultured RPE cells and the exosomes derived from CM and from the aqueous humor (AH) of AMD patients by LC-ESI-MS/MS. Finally, LC-MRM was performed on the AH from patients and controls, which revealed that cathepsin D, cytokeratin 8, and four other proteins increased in the AH of AMD patients. The present study has identified potential biomarkers and therapeutic targets for AMD treatment, such as proteins related to the autophagy-lysosomal pathway and epithelial-mesenchymal transition, and demonstrated a novel and effective approach to identifying AMD-associated proteins that might be secreted by RPE in vivo in the form of exosomes. The proteomics-based characterization of this multifactorial disease could help to match a particular marker to particular target-based therapy in AMD patients with various phenotypes. © 2014 American Chemical Society.


The present invention relates to a pharmaceutical composition for the treatment of cancer comprising a chlorin e6-folic acid conjugate compound and chitosan, and more particularly, to a pharmaceutical composition for photodynamic therapy of solid tumors comprising the novel chlorin e6-folic acid conjugate compound or a pharmaceutically acceptable salt thereof and chitosan as an active ingredient, in which the novel compound is prepared by linking chlorin e6 to folic acid, and effectively produces singlet oxygen in various media and has much better tumor selectivity than the known porphyrin-based photosensitizers, thereby being used effectively in photodynamic treatment for malignant tumors.


The present invention relates to a novel chlorin e6-folic acid conjugate, a preparation method thereof, and a pharmaceutical composition for the treatment of cancer comprising the same, and more particularly, to a novel compound prepared by linking chlorin e6 to folic acid, which effectively produces singlet oxygen in various media and has much better tumor selectivity than the known porphyrin-based photosensitizers, thereby being used effectively in photodynamic therapy for malignant tumors, a preparation method thereof, and a pharmaceutical composition for photodynamic treatment of solid tumors comprising the compound as an active ingredient.


PubMed | Diatech Korea Co. and Konkuk University
Type: Journal Article | Journal: BMB reports | Year: 2014

Age-related macular degeneration (AMD) is the leading cause of blindness in the world. Evidence indicates that the suppression of the ubiquitin-proteasome system (UPS) contributes to the accumulation of toxic proteins and inflammation in retinal pigment epithelium (RPE), the functional abnormalities and/or the degeneration of which are believed to be the initiators and major pathologies of AMD. To identify new protein associations with the altered UPS in AMD, we used LC-ESI-MS/MS to perform a proteomic analysis of the aqueous humor (AH) of AMD patients and matched control subjects. Six UPS-related proteins were present in the AH of the patients and control subjects. Four of the proteins, including 26S proteasome non-ATPase regulatory subunit 1 (Rpn2), were increased in patients, according to semi-quantitative proteomic profiling. An LC-MRM assay revealed a significant increase of Rpn2 in 15 AMD patients compared to the control subjects, suggesting that this protein could be a biomarker for AMD.

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