Nelumbo nucifera Receptaculum Extract Suppresses Angiotensin II-Induced Cardiomyocyte Hypertrophy

Nelumbo nucifera Gaertn. (lotus) is an important medicinal plant, and many parts of the plant have been investigated for their therapeutic effects. However, the therapeutic effect of receptacles of lotuses on pathological cardiomyocyte hypertrophy has not been investigated yet. Therefore, the current study aimed to determine the protective effect of lotus against angiotensin II (Ang II)-induced cardiomyocyte hypertrophy in vitro. Ang II was used to induce hypertrophy of H9c2 cells. The lotus receptacle powder (MeOH extract of receptaculum Nelumbinis; MRN) used in the experiments was prepared by MeOH extraction and subsequent evaporation. To evaluate the effect of MRN on cardiomyocyte hypertrophy, cell size, protein synthesis, and hypertrophic marker expressions were examined. The antioxidant ability of MRN was determined by using CM-H2DCFDA, a general oxidative stress indicator. Ang II-induced cardiomyocyte hypertrophy was significantly attenuated by 5 µg/mL of MRN, as confirmed by the reductions in cell size, protein synthesis, and hypertrophic marker expression. MRN also attenuated Ang II-induced excessive intracellular reactive oxygen species (ROS) production through the suppression of protein kinase C (PKC), extracellular-signal-regulated kinase (ERK), and NF-κB activation and subsequent type I angiotensin receptor (AT1R), receptor for advanced glycation end products (RAGE), and NADPH oxidase (NOX) expression. MRN exerted a significant protective effect against Ang II-induced cardiomyocyte hypertrophy through suppression of PKC-ERK signaling, and this subsequently led to attenuation of intracellular ROS production.ope

Soluble RAGE attenuates AngII-induced endothelial hyperpermeability by disrupting HMGB1-mediated crosstalk between AT1R and RAGE

Increased endothelial permeability, one of the earliest signs of endothelial dysfunction, is associated with the development of cardiovascular diseases such as hypertension and atherosclerosis. Recent studies suggest that the receptor for advanced glycation end products (RAGE) regulates endothelial permeability in inflammation. In the present study, we investigated the regulatory mechanism of RAGE in endothelial hyperpermeability induced by angiotensin II (Ang II), a well-known inflammatory mediator, and the potential therapeutic effect of soluble RAGE (sRAGE), a decoy receptor for RAGE ligands. For in vitro studies, Ang II-treated human umbilical vein endothelial cells (HUVECs) were treated with siRNA specific to either RAGE or sRAGE to disrupt RAGE-mediated signaling. Endothelial permeability was estimated using FITC-labeled dextran 40 and a resistance meter. To evaluate intercellular junction disruption, VE-cadherin expression was examined by western blotting and immunocytochemistry. Ang II increased the expression of the Ang II type 1 receptor (AT1R) and RAGE, and this increase was inhibited by sRAGE. sRAGE prevented Ang II-induced VE-cadherin disruption in HUVECs. For in vivo studies, Ang II-infused, atherosclerosis-prone apolipoprotein E knockout mice were utilized. Endothelial permeability was assessed by Evans blue staining of the aorta. Ang II increased endothelial barrier permeability, and this effect was significantly attenuated by sRAGE. Our data demonstrate that blockade of RAGE signaling using sRAGE attenuates Ang II-induced endothelial barrier permeability in vitro and in vivo and indicate the therapeutic potential of sRAGE in controlling vascular permeability under pathological conditions.ope

TNF-α-Induced YAP/TAZ Activity Mediates Leukocyte-Endothelial Adhesion by Regulating VCAM1 Expression in Endothelial Cells

YAP/TAZ, a transcriptional co-activator of Hippo pathway, has emerged as a central player in vessel homeostasis such as sprouting angiogenesis and vascular barrier stabilization, during development. However, the role of YAP/TAZ in pathological angiogenesis remains unclear. Here, we demonstrated that YAP/TAZ is a critical mediator in leukocyte-endothelial adhesion induced by the vascular inflammatory cytokine TNF-α. YAP/TAZ was dephosphorylated, translocated from the cytosol to the nucleus, and activated by TNF-α in endothelial cells. A specific inhibitor of Rho GTPases suppressed the TNF-α-induced dephosphorylation of YAP. Knockdown of YAP/TAZ using siRNA significantly reduced the expression of the leukocyte adhesion molecule VCAM1 induced by TNF-α. The adhesion of monocytes to endothelial cells was also markedly reduced by YAP/TAZ silencing. However, knockdown of YAP/TAZ did not affect TNF-α-induced NF-κB signaling. Overall, these results suggest that YAP/TAZ plays critical roles in regulating TNF-α-induced endothelial cell adhesive properties without affecting the NF-κB pathway, and implicate YAP/TAZ as a potential therapeutic target for treating inflammatory vascular diseases.ope

신호전달 G 단백질 베타감마 소단위가 자외선에 의한 MAP kinase 신호전달계의 활성화에 미치는 영향

학위논문(석사)--서울대학교 대학원 :의학과 생화학전공,2001.Maste

자외선에 의한 mitogen-activated protein kinases 활성화에서 G 단백질 베타감마 소단위의 역할

Thesis (doctoral)--서울대학교 대학원 :의학과 생화학,2003.Docto

Salvianolic Acid B Inhibits Atherogenesis of Vascular Cells through Induction of Nrf2-dependent Heme Oxygenase-1

Aims: Salvianolic acid B (Sal B), one of the most active components of Danshen extracts, has beneficial roles in the prevention and treatment of cardiovascular diseases. However, the precise mechanism by which Sal B exerts its effects on vascular cells is unclear. We aimed to elucidate the effects of Sal B on vascular cells and the underlying mechanisms. Methods and Results: Treatment of vascular smooth muscle cells with Sal B effectively inhibited platelet-derived growth factor (PDGF)-induced cell proliferation and migration, and markedly increased heme oxygenase-1 (HO-1) expression. These changes were accompanied by antioxidant effects, including decreases in the generation of reactive oxygen species and the NADP/NADPH ratio. In human umbilical vein endothelial cells, Sal B also strongly induced HO-1 and effectively inhibited tumor necrosis factor- α-induced NF- κB activation. Knockdown of HO-1 expression by siRNA abolished the effects of Sal B in vascular cells and prevented the inhibition of proliferation, migration, and inflammation in HO-1-deficient cells. In ex vivo culture of arterial rings isolated from nuclear factor-E2-related factor 2 (Nrf2)-knockout mice, Sal B neither induce HO-1 expression and nor inhibit PDGF-induced neointimal hyperplasia in arteries, suggesting that Nrf2 plays a crucial role in the induction of HO-1 expression. Conclusions: We conclude that Sal B exerts antiatherogenic effects by inhibiting the proliferation, migration, and inflammation of vascular cells through induction of HO-1 via Nrf2 activation.ope

Role of Protein Kinases and Their Inhibitors in Radiation Response of Tumor Cells

Phosphorylation, the addition of a phosphate group to a molecule, is an effective way of regulating the biological properties of that molecule. Protein phosphorylation is a post-translational modification of proteins and affects cellular signaling transduction. Protein kinases induce phosphorylation by catalyzing the transfer of phosphate groups to serine, threonine, and tyrosine residues on protein substrates. Consistent with their roles in cancer, protein kinases have emerged as one of the most clinically useful target molecules in pharmacological cancer therapy. Intrinsic or acquired resistance of cancers against anti-cancer therapeutics, such as ionizing radiation, is a major obstacle for the effective treatment of many cancers. In this review, we describe key aspects of various kinases acting on proteins. We also discuss the roles of protein kinases in the pathophysiology and treatment of cancer. Because protein kinases correlate with radiation resistance in various types of cancer, we focus on several kinases responsible for radiation resistance and/or sensitivity and their therapeutic implications. Finally, we suggest some ongoing radiation-sensitization strategies using genetic loss and/or kinase inhibitors that can counteract radiation resistance-related protein kinases.restrictio

Antioxidant activity of caffeoyl-prolyl-histidine amide and its effects on PDGF-induced proliferation of vascular smooth muscle cells

Caffeic acid (CA) is one of the antioxidants found in plants, which protects vascular cells against vascular injuries from oxidative stress. In our previous study, caffeoyl-prolyl-histidine amide (CA-L-Pro-L-His-NH2; CA-PH; a CA derivative) was synthesized, which exhibited a strong antioxidant activity with sufficient stability. In this study, we investigated the role of CA-PH in vascular smooth muscle cells (VSMCs) and confirmed the enhanced antioxidant activity of CA-PH compared with that of CA. In in vitro tube assays, CA-PH showed a higher free-radical-scavenging activity and lipid-peroxidation-inhibition activity than those of CA. In VSMCs, CA-PH significantly reduced hydrogen peroxide-induced ROS generation and increased the expression of heme oxygenase-1. Moreover, CA-PH effectively inhibited the platelet-derived growth factor-induced cellular proliferation of VSMCs, which was confirmed by a decrease in the expression of the proliferating cell nuclear antigen and the phosphorylation of Akt.ope

Inhibition of Akt/FOXO3a signaling by constitutively active FOXO3a suppresses growth of follicular thyroid cancer cell lines.

Akt-dependent FOXO3a cytoplasmic translocation is an important tumorigenic mechanism for escaping from apoptosis in cancer cells. In the present study, we examined whether non-phosphorylatable FOXO3a can inhibit cell growth of various follicular thyroid carcinoma (FTC) cell lines. Adenovirus carrying the FOXO3a-triple mutant (TM) sequence including point mutations at three Akt phosphorylation sites (Ad-FOXO3a-TM) was generated and transduced to the cells to mimic inhibition of Akt/FOXO3a signal. Transduction of Ad-FOXO3a-TM to FTC133 cells induced cell cycle arrest and apoptosis. Injection of Ad-FOXO3a-TM suppressed the growth of xenograft tumors in athymic mice. Consequently, our results indicate that gene therapy based on Ad-FOXO3a-TM has therapeutic potential for FTC.ope

Nonmuscle myosin heavy chain and histone H3 are intracellular binding partners of lithospermic acid B and mediate its antiproliferative effect on VSMCs.

Lithospermic acid B (LAB), an active component of danshen, is known to inhibit the proliferation of vascular smooth muscle cells (VSMCs) and has pharmacological activity scavenging free radicals in VSMCs. However, the precise mechanism through which LAB exerts its antiproliferative effect is unclear. Therefore, we investigated how LAB regulates cellular proliferation in primary cultured rat VSMCs. Using fluorescein isothiocyanate (FITC)-conjugated LAB to track its cellular localization, we show that LAB localizes to the nucleus, specifically to the nucleolus, where it binds to histone H3, leading to the inhibition of the platelet-derived growth factor (PDGF)- induced phosphorylation of histone H3. LAB also only moves into the nucleus during the normal expression of nonmuscle myosin heavy chain (NMHC-IIA), which is associated with LAB in VSMCs. Notably, LAB suppressed the PDGF-induced phosphorylation of Akt and the expression of cyclin D2 in the presence of NMHC-IIA expression. Knockdown of NMHC-IIA expression impeded the function of LAB, which was then unable to inhibit the PDGF-induced proliferation of VSMCs. We conclude that LAB modulates the PDGF-induced proliferation of VSMCs by interacting with NMHC-IIA, which allows LAB to localize in the nucleus and to suppress the PDGF-induced proliferation of VSMCs.ope