Ji-Yoon Kim

The non-provitamin A carotenoid, lutein, inhibits NF-κB-dependent gene expression through redox-based regulation of the phosphatidylinositol 3-kinase/PTEN/Akt and NF-κB-inducing kinase pathways: Role of H2O2 in NF-κB activation

Reactive oxygen species (ROS) have been implicated in the regulation of NF-kappaB activation, which plays an important role in inflammation and cell survival. However, the molecular mechanisms of ROS in NF-kappaB activation remain poorly defined. We found that the non-provitamin A carotenoid, lutein, decreased intracellular H(2)O(2) accumulation by scavenging superoxide and H(2)O(2) and the NF-kappaB-regulated inflammatory genes, iNOS, TNF-alpha, IL-1beta, and cyclooxygenase-2, in lipopolysaccharide (LPS)-stimulated macrophages. Lutein inhibited LPS-induced NF-kappaB activation, which highly correlated with its inhibitory effect on LPS-induced IkappaB kinase (IKK) activation, IkappaB degradation, nuclear translocation of NF-kappaB, and binding of NF-kappaB to the kappaB motif of the iNOS promoter. This compound inhibited LPS- and H(2)O(2)-induced increases in phosphatidylinositol 3-kinase (PI3K) activity, PTEN inactivation, NF-kappaB-inducing kinase (NIK), and Akt phosphorylation, which are all upstream of IKK activation, but did not affect the interaction between Toll-like receptor 4 and MyD88 and the activation of mitogen-activated protein kinases. The NADPH oxidase inhibitor apocynin and gp91(phox) deletion reduced the LPS-induced NF-kappaB signaling pathway as lutein did. Moreover, lutein treatment and gp91(phox) deletion decreased the expressional levels of the inflammatory genes in vivo and protected mice from LPS-induced lethality. Our data suggest that H(2)O(2) modulates IKK-dependent NF-kappaB activation by promoting the redox-sensitive activation of the PI3K/PTEN/Akt and NIK/IKK pathways. These findings further provide new insights into the pathophysiological role of intracellular H(2)O(2) in the NF-kappaB signal pathway and inflammatory process.

Filaggrin knockdown and Toll‐like receptor 3 (TLR3) stimulation enhanced the production of thymic stromal lymphopoietin (TSLP) from epidermal layers

Abstract:  Keratinocytes constitute the first‐line barrier against exogenous antigens and contain Toll‐like receptors (TLRs), which function as pattern‐recognition molecules to activate antimicrobial innate immune responses. In an effort to ascertain whether or not filaggrin (filament‐aggregating protein) expression affected the TLR‐mediated responses of keratinocytes, we transfected filaggrin siRNA into HaCaT human keratinocyte cells and determined that thymic stromal lymphopoietin (TSLP) and IL‐6 secretion were increased by poly(I:C) stimulus. Additionally, TSLP expression is increased in filaggrin knockdown as well as TLR3 stimulation in reconstituted human epidermal layers. Therefore, the findings of this study show that reduced filaggrin levels may influence innate immune responses via TLR stimuli and may contribute to the pathogenesis of inflammatory skin disease via TSLP expression.

Specific activation of insulin-like growth factor-1 receptor by ginsenoside Rg5 promotes angiogenesis and vasorelaxation.

Background: The mechanism by which ginsenoside Rg5 regulates vascular function remains unclear. Results: Rg5 increases angiogenesis and vasorelxation by activating multiple signal transduction pathways downstream of insulin-like growth fastor-1 receptor (IGF-1R). Conclusion: Rg5 promotes endothelial cell function through activation of IGF-1R. Significance: These findings reveal a mechanism for the positive regulation of vascular function by Rg5-mediated IGF-1R activation. Ginsenoside Rg5 is a compound newly synthesized during the steaming process of ginseng; however, its biological activity has not been elucidated with regard to endothelial function. We found that Rg5 stimulated in vitro angiogenesis of human endothelial cells, consistent with increased neovascularization and blood perfusion in a mouse hind limb ischemia model. Rg5 also evoked vasorelaxation in aortic rings isolated from wild type and high cholesterol-fed ApoE−/− mice but not from endothelial nitric-oxide synthase (eNOS) knock-out mice. Angiogenic activity of Rg5 was highly associated with a specific increase in insulin-like growth factor-1 receptor (IGF-1R) phosphorylation and subsequent activation of multiple angiogenic signals, including ERK, FAK, Akt/eNOS/NO, and Gi-mediated phospholipase C/Ca2+/eNOS dimerization pathways. The vasodilative activity of Rg5 was mediated by the eNOS/NO/cGMP axis. IGF-1R knockdown suppressed Rg5-induced angiogenesis and vasorelaxation by inhibiting key angiogenic signaling and NO/cGMP pathways. In silico docking analysis showed that Rg5 bound with high affinity to IGF-1R at the same binding site of IGF. Rg5 blocked binding of IGF-1 to its receptor with an IC50 of ∼90 nmol/liter. However, Rg5 did not induce vascular inflammation and permeability. These data suggest that Rg5 plays a novel role as an IGF-1R agonist, promoting therapeutic angiogenesis and improving hypertension without adverse effects in the vasculature.

TRAIL negatively regulates VEGF-induced angiogenesis via caspase-8-mediated enzymatic and non-enzymatic functions

Solid tumors supply oxygen and nutrients required for angiogenesis by producing vascular endothelial growth factor (VEGF). Thus, inhibitors of VEGF signaling abrogate tumor angiogenesis, resulting in the suppression of tumor growth and metastasis. We here investigated the effects of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) on VEGF-induced angiogenesis. TRAIL inhibited VEGF-induced in vitro angiogenesis of human umbilical vein endothelial cells (HUVECs) and in vivo neovascularization in chicken embryos and mice. TRAIL blocked VEGF-induced angiogenic signaling by inhibiting ERK, Src, FAK, paxillin, Akt, and eNOS. Further, TRAIL blocked intracellular Ca2+ elevation and actin reorganization in HUVECs stimulated with VEGF, without inhibiting VEGF receptor-2 tyrosine phosphorylation. TRAIL increased caspase-8 activity, without inducing caspase-9/-3 activation and apoptosis. Moreover, TRAIL resulted in cleavage of FAK into FAK-related non-kinase-like fragments in VEGF-stimulated HUVECs, which was blocked by a caspase-8 inhibitor and cellular caspase-8-like inhibitory protein. Biochemical and pharmacological inhibition of caspase-8 and FAK blocked the inhibitory effects of TRAIL on VEGF-stimulated anti-angiogenic signaling and events. In addition, caspase-8 knockdown also suppressed VEGF-mediated signaling and angiogenesis, suggesting that procaspase-8 plays a role of a non-apoptotic modulator in VEGF-induced angiogenic signaling. These results suggest that TRAIL inhibits VEGF-induced angiogenesis by increasing caspase-8 activity and subsequently decreasing non-apoptotic signaling functions of procaspase-8, without inducing caspase-3 activation and endothelial cell cytotoxicity. These data indicate that caspase-8 may be used as an anti-angiogenic drug for solid tumors resistant to TRAIL and anti-tumor drugs.

Sec16A is critical for both conventional and unconventional secretion of CFTR

CFTR is a transmembrane protein that reaches the cell surface via the conventional Golgi mediated secretion pathway. Interestingly, ER-to-Golgi blockade or ER stress induces alternative GRASP-mediated, Golgi-bypassing unconventional trafficking of wild-type CFTR and the disease-causing ΔF508-CFTR, which has folding and trafficking defects. Here, we show that Sec16A, the key regulator of conventional ER-to-Golgi transport, plays a critical role in the ER exit of protein cargos during unconventional secretion. In an initial gene silencing screen, Sec16A knockdown abolished the unconventional secretion of wild-type and ΔF508-CFTR induced by ER-to-Golgi blockade, whereas the knockdown of other COPII-related components did not. Notably, during unconventional secretion, Sec16A was redistributed to cell periphery and associated with GRASP55 in mammalian cells. Molecular and morphological analyses revealed that IRE1α-mediated signaling is an upstream regulator of Sec16A during ER-to-Golgi blockade or ER stress associated unconventional secretion. These findings highlight a novel function of Sec16A as an essential mediator of ER stress-associated unconventional secretion.

Influence of intrinsic factors and extrinsic product information on acceptability for Mulnaengmyeon (Korean traditional cold noodle) broth

Despite expansion of the mulnaengmyeon market in Korea, there have been no studies about consumer attitudes toward mulnaengmyeon. This study was conducted to investigate influences of intrinsic and extrinsic factors on consumer acceptability for mulnaengmyeon broths and to examine differences in use of information between consumers of different ages. Sensory characteristics of mulnaengmyeon broths were examined using descriptive analysis by trained panels. Old and young consumers were separately recruited for consumer test. Each consumer participated in acceptability evaluation for mulnaengmyeon either in blind or informed conditions. In informed condition, product package was provided along with the corresponding mulnaengmyeon sample. Overall, consumer acceptability for mulnaengmyeon broth was observed to be primarily influenced by sensory characteristics, but it was further adjusted by the influence of brand awareness. Mulnaengmyeon acceptability was little affected by price and package. Difference in use of intrinsic and extrinsic information depending on consumers’ age was not observed well in this study.

pH-Dependent Release Property of Agar Beads Containing Chitosan Particles

Agar beads containing chitosan particles were prepared by dropping hot suspension of agar/chitosan (2/1, w/w) into cold distilled water. The bead size was 2–3 mm and the cross section of the bead revealed a porous structure on FE-SEM (Field Emission Scanning electron microscopy) photos. The pH-dependent release property of the bead was observed using either blue dextran or FITC-dextran (Fluorescein isothiocyanate-dextran) as a dye. The % releases of blue dextran for 6 h were 42% at pH 3.5, 48% at pH 5.5 and 52% at pH 8.0. Obviously, the release was significantly suppressed at acidic pHs. This is possibly because the positive charge intensity of chitosan becomes stronger at an acidic pH. As a result, it tends to interact with negatively charged blue dextran, leading to a suppressed release at acidic pHs. On the other hand, the % releases of FITC-dextran for 6 h were 88% at pH 4.5, 80% at pH 5.5 and 76% at pH 8.0. The release was somewhat promoted at acidic pHs. At an acidic pH such as pH 3.5, chitosan could be dissolved within agar beads, giving rise to cavities. In addition, there might be no electrostatic interaction between positively charged chitosan and neutral FITC-dextran. Therefore, FITC-dextran would readily release through the cavities, resulting in a higher release at an acidic pH.