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ABSTRACT: Two genes on chromosome 21, namely dual specificity tyrosine phosphorylation-regulated kinase 1A (Dyrk1A) and regulator of calcineurin 1 (RCAN1), have been implicated in some of the phenotypic characteristics of Down syndrome, including the early onset of Alzheimer disease. Although a link between Dyrk1A and RCAN1 and the nuclear factor of activated T cells (NFAT) pathway has been reported, it remains unclear whether Dyrk1A directly interacts with RCAN1. In the present study, Dyrk1A is shown to directly interact with and phosphorylate RCAN1 at Ser(112) and Thr(192) residues. Dyrk1A-mediated phosphorylation of RCAN1 at Ser(112) primes the protein for the GSK3β-mediated phosphorylation of Ser(108). Phosphorylation of RCAN1 at Thr(192) by Dyrk1A enhances the ability of RCAN1 to inhibit the phosphatase activity of calcineurin (Caln), leading to reduced NFAT transcriptional activity and enhanced Tau phosphorylation. These effects are mediated by the enhanced binding of RCAN1 to Caln and its extended half-life caused by Dyrk1A-mediated phosphorylation. Furthermore, an increased expression of phospho-Thr(192)-RCAN1 was observed in the brains of transgenic mice overexpressing the Dyrk1A protein. These results suggest a direct link between Dyrk1A and RCAN1 in the Caln-NFAT signaling and Tau hyperphosphorylation pathways, supporting the notion that the synergistic interaction between the chromosome 21 genes RCAN1 and Dyrk1A is associated with a variety of pathological features associated with DS.
Journal of Biological Chemistry 09/2011; 286(46):40401-12. · 4.77 Impact Factor
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Young Shin Ryu,
So Young Park,
Min-Su Jung,
Song-Hee Yoon,
Mi-Yang Kwen,
Sun-Young Lee,
Sun-Hee Choi,
Chinzorig Radnaabazar,
Mi-Kyoung Kim,
Hangun Kim,
Kwonseop Kim,
Woo-Joo Song,
Sul-Hee Chung
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ABSTRACT: The dual-specificity tyrosine(Y)-phosphorylation-regulated kinase 1A (Dyrk1A) gene is located on human chromosome 21 and encodes a proline-directed protein kinase that might be responsible for mental retardation and early onset of Alzheimer's disease (AD) in Down syndrome (DS) patients. Presenilin 1 (PS1) is a key component of the γ-secretase complex in the generation of β-amyloid (Aβ), an important trigger protein in the pathogenesis of AD. Increased Dyrk1A expression has been reported in human AD and DS brains. We previously showed that Dyrk1A increased Aβ production in mammalian cells and transgenic mice that over-express Dyrk1A. In this study, we describe a potential mechanism by which Aβ is increased in Dyrk1A-over-expressing DS and AD brains. First, we show that PS1 is phosphorylated by the Dyrk1A at Thr(354) and that this phosphorylation increases γ-secretase activity. Then, using transgenic mice that over-express human Dyrk1A, we demonstrate that phospho-Thr354-PS1 (pT354-PS1) expression is enhanced when Dyrk1A level is increased. We also show that pT354-PS1 is more stable than the unphosphorylated form of PS1. These results reveal a potential regulatory link between Dyrk1A and PS1 in the Aβ pathway of DS and AD brains, suggesting that up-regulated Dyrk1A may accelerate AD pathogenesis through PS1 phosphorylation.
Journal of Neurochemistry 04/2010; 115(3):574-84. · 4.06 Impact Factor
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ABSTRACT: Recent reports demonstrated that a hemangioblast population emerged during hematopoietic development in both mouse and human embryonic stem cell (hESC) differentiation cultures.
In this study, a new uncharacterized hESC line, SNUhES#3, was studied for its capacity to proliferate with STO cells and differentiate into hemangioblasts in co-culture with OP9 cells.
We were able to obtain CD34(+)CD45(-) cells from SNUhES#3 cells after 12 days of in vitro culture, and this cell population could be maximized to 12.6% of the total. These cells, derived from SNUhES#3, showed the morphology of hematopoietic precursor cells and endothelial lineage cells with high efficiency. Reverse transcription polymerase chain reaction (RT-PCR) analysis showed that the hematopoietic markers CD34, GATA2, and LMO2 were co-expressed with the endothelial marker CD31 from day 8, whereas ES cell marker OCT4 no longer existed at an early stage. Moreover, we found that the efficacy of colony forming by SNUhES#3 cells is better than that of H9 cells.
These findings provide evidence that SNUhES#3 cells can be used as an established human ESC line, and co-culture with OP9 can induce SNUhES#3 cells to differentiate into hemangioblasts, the common precursors of the hematopoietic and endothelial lineages.
Life sciences 05/2009; 85(1-2):39-45. · 2.56 Impact Factor
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ABSTRACT: Capsaicin, the pungent component of chilli peppers, is known to induce mediators of hematopoiesis. We investigated the effect of capsaicin on hematopoiesis in mouse progenitor cells. Treatment of mouse bone marrow cells with capsaicin induced the formation of colony of burst-forming units-erythroid (BFU-E). We also found that the number of erythropoietin receptor (EpoR)-positive cells was increased by capsaicin. To clarify the effect of capsaicin on erythroid lineage, BFU-E colonies were separated from non-BFU-E colonies by colony-picking after in vitro culture of mouse bone marrow cells. Quantitative RT-PCR analysis revealed that capsaicin stimulated the expression of the erythroid-specific genes encoding EpoR, glycophorin A (GPA), beta-globin (Hbb-b1), GATA-1, PU.1, nuclear factor erythroid-derived 2 (NF-E2), and Krüppel-like factor 1 (KLF1) in the BFU-E colonies. Furthermore, capsaicin could effectively stimulate the transfected GATA-1 promoter in K562 cells. GATA-1 is known as an essential transcription factor for the development of erythroid cells. Our results show that development of the erythroid lineage from bone marrow cells can be induced by treatment with capsaicin, and that GATA-1 seems to play a role in this induced erythroid maturation.
Experimental and Molecular Medicine 07/2007; 39(3):278-83. · 2.48 Impact Factor
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Chung-Hyun Cho,
Richard A Kammerer,
Hyuek Jong Lee,
Michel O Steinmetz, Young Shin Ryu,
Sung Ho Lee,
Kunio Yasunaga,
Kyung-Tae Kim,
Injune Kim,
Han-Ho Choi,
Won Kim,
Sung Hyun Kim,
Sung Kwang Park,
Gyun Min Lee,
Gou Young Koh
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ABSTRACT: Angiopoietin-1 (Ang1) has potential therapeutic applications in inducing angiogenesis, enhancing endothelial cell survival, and preventing vascular leakage. However, production of Ang1 is hindered by aggregation and insolubility resulting from disulfide-linked higher-order structures. Here, by replacing the N-terminal portion of Ang1 with the short coiled-coil domain of cartilage oligomeric matrix protein (COMP), we have generated a soluble, stable, and potent Ang1 variant, COMP-Ang1. This variant is more potent than native Ang1 in phosphorylating the tyrosine kinase with Ig and epidermal growth factor homology domain 2 (Tie2) receptor and Akt in primary cultured endothelial cells, enhancing angiogenesis in vitro and increasing adult angiogenesis in vivo. Thus, COMP-Ang1 is an effective alternative to native Ang1 for therapeutic angiogenesis in vivo.
Proceedings of the National Academy of Sciences 05/2004; 101(15):5547-52. · 9.68 Impact Factor
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ABSTRACT: Interaction between ephrinB2 and EphB4 in endothelial cells at the arterial-venous capillary interface is critical for proper embryonic capillary morphogenesis. However, the intracellular downstream signaling of ephrinB2-EphB in vascular endothelial cells is unknown. This study examined the effect of ephrinB2-induced activation of EphB kinases on vascular endothelial growth factor (VEGF)- and angiopoietin-1 (Ang1)-induced Ras/mitogen-activated protein kinase (MAPK) signaling cascades in human umbilical vein endothelial cells (HUVECs). Reverse transcriptase-polymer chain reaction results showed that HUVECs expressed three kinds of EphB kinases known to bind to ephrinB2: EphB2, EphB3, and EphB4. EphrinB2 not only increased the phosphorylation of EphB2 and EphB4 in a time-dependent manner but also increased recruitment of p120-Ras-GTPase-activating protein (p120-RasGAP) to EphB2 and EphB4. Accordingly, ephrinB2 inhibited VEGF- and Ang1-induced Ras-MAPK activities, whereas ephrinB2 did not alter VEGF-induced Flk phosphorylation or Ang1-induced Tie2 phosphorylation. Furthermore, ephrinB2 suppressed VEGF- and Ang1-induced proliferation and/or migration, which are mediated mainly through Ras/MAPK signaling cascades. From these results, we propose that ephrinB2-EphB, signaling through Ras/MAPK cascade, may be critical for proper morphogenesis of capillary endothelium through the arrest of endothelial cell proliferation and migration at the arterial-venous interface.
The FASEB Journal 08/2002; 16(9):1126-8. · 5.71 Impact Factor
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ABSTRACT: Normally, tissue factor (TF) is not expressed on the surface of endothelial cells, but its expression can be induced by vascular endothelial growth factor (VEGF) and tumor necrosis factor (TNF)-a. However, the signaling pathway(s) affecting this induction is unknown. Using human umbilical vein endothelial cells, we found that inhibitors of guanine-cytosine-rich DNA binding protein and nuclear factor (NF)-kB suppressed VEGF- and TNF-a-induced expression and activity of TF. However, unexpectedly, phosphatidylinositol (PI) 3'-kinase inhibitor enhanced the VEGF- and TNF-a-induced expression and activity of TF. Angiopoietin-1 (Ang1), a strong activator of intracellular PI 3'-kinase/Akt, inhibited the induction of TF by VEGF and TNF-a, whereas Ang1 itself did not produce any significant effect on TF. Selective activation (or inactivation) of PI 3'-kinase/Akt by using adenoviral transfer reduced (or enhanced) TNF-a-induced expression of TF mRNA and protein, regardless of Ang1 treatment. From these results, we conclude that Ang1 inhibits the up-regulation of TF expression, possibly through activation of PI 3'-kinase/Akt in endothelial cells. Ang1 may be useful as an inhibitor of VEGF- and TNF-a-induced coagulation, inflammation, and cancer progression.
The FASEB Journal 02/2002; 16(1):126-8. · 5.71 Impact Factor
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ABSTRACT: Angiopoietin-2 (Ang2) is a naturally occurring antagonist of angiopoietin-1 (Ang1) that competes for binding to the Tie2 receptor
and blocks Ang1-induced Tie2 autophosphorylation during vasculogenesis. Using the polymerase chain reaction, we isolated a
cDNA encoding a novel shorter form of Ang2 from human umbilical vein endothelial cell cDNA and have designated it angiopoietin-2443 (Ang2443), because it contains 443 amino acids. Part of the coiled-coil domain (amino acids 96–148) is absent in Ang2443 because of alternative splicing of the gene. Like Ang2, recombinant Ang2443expressed in COS-7 cells is secreted as a glycosylated homodimeric protein. Recombinant Ang2443 binds to the Tie2 receptor but does not induce Tie2 phosphorylation. Pre-occupation of Ang2443 on Tie2 inhibits Ang1 or Ang2 binding and inhibits Ang1-induced phosphorylation. Expression ofAng2
443 mRNA is detectable in primary endothelial cells, several nonendothelial tumor cell lines, and primary tumor tissues. Interestingly,
two cervical carcinoma cell lines express relatively moderate levels of Ang2
443 mRNA and protein. Macrophages express mainly Ang2 mRNA, but the expression of Ang2
443 mRNA is temporarily up-regulated during macrophage differentiation. These results suggest that Ang2443 is a functional antagonist of Ang1 and could be an important regulator of angiogenesis during some tumorigenic and inflammatory
processes.
Journal of Biological Chemistry 06/2000; 275(24):18550-18556. · 4.77 Impact Factor
