Acylated saponins and flavonoid glycosides from the fruits of Stewartia koreana.

Three acylated saponins and three flavonoid glycosides, along with nine known flavonoids, were isolated from the fruits of Stewartia koreana Nakai ex Rehder (Theaceae) using relative mass defect filtering analysis. The structures of these compounds were determined by performing spectroscopic analyses and using chemical methods. Furthermore, all the isolates were evaluated for their effects on the mRNA expression of the genes for proprotein convertase subtilisin/kexin type 9 (PCSK9) and low-density lipoprotein receptor (LDLR) as well as their inhibitory activities on PCSK9 and LDLR binding. None of the isolates was deemed to be active in PCSK9-LDLR binding inhibition. However, (+)-catechin was found to inhibit PCSK9 expression and increase LDLR expression, suggesting the potential of (+)-catechin to lower cholesterol level via the downregulation of PCSK9 expression.

Nickel Oxide Nanoparticles Doped Liquid Crystal System for Superior Electro-Optical Properties.

We examined the properties of nematic liquid crystal (N-LC) systems with dispersed nickel oxide nanoparticles (NPs). Uniform LC alignments with regular pretilt angles were achieved on rubbed polymer surface regardless of NiO nanoparticles concentration. We confirmed the electro-optical characteristics of twisted nematic (TN) cells containing NiO nanoparticles on rubbed polymer surface, which exhibited lower threshold voltages and faster response times with less capacitance hysteresis than pure LC cells. It is clear that the response time of TN cells on rubbed polymer surfaces decreases with increasing the NiO nanoparticles concentration. These results demonstrate the relationship between NP doping concentration and trapping of impurity ions, and were confirmed by a software simulation of electric flux and field density. NiO nanoparticles in the LC cells focused the electric field flux and strengthened the electric field. Further, NiO nanoparticles in LC medium trapped charged ionic impurities and suppressed the screen effect, leading to a stronger electric field and the van der Waals interactions between LC molecules and the alignment layers.

High performance twisted nematic liquid crystal display with solution-derived YZO surface modification via ion-beam irradiation.

Solution-derived YZO films were investigated as liquid crystal (LC) alignment layers modified by ion beam (IB) irradiation. Solution processing was adopted in place of the sputtering method for the deposition of YZO films as LC alignment layers. Uniform and homogeneous LC alignment was achieved to produce a high performance LC system. X-ray photoelectron spectroscopy analysis showed that surface reformation of YZO films by annealing and IB irradiation affects the uniformity of the LC alignment. Superior electro-optical characteristics of twisted nematic LC cells constructed from IB-irradiated YZO films were observed, which indicates that the proposed solution-derived YZO films have strong potential for use in the production of advanced LC displays.

Protective immunity of Pichia pastoris-expressed recombinant envelope protein of Japanese encephalitis virus.

Japanese encephalitis virus (JEV) envelope (E) protein holds great promise for use in the development of a recombinant vaccine. Purified recombinant E (rE) protein may be useful for numerous clinical applications; however, there are limitations in using the Escherichia coli expression system for producing high-quality rE protein. Therefore, in this study, the yeast expression system was used to generate the rE protein. For protein production using the yeast system, the full-length JEV E gene was cloned into Pichia pastoris. SDS-PAGE and immunoblotting analysis demonstrated that the rE protein had a molecular mass of 58 kDa and was glycosylated. The predicted size of the mature unmodified E protein is 53 kDa, suggesting that post-translational modifications resulted in the higher molecular mass. The rE protein was purified to greater than 95% purity using combined ammonium sulfate precipitation and a SP-Sepharose Fast Flow column. This purified rE protein was evaluated for immunogenicity and protective efficacy in mice. The survival rates of mice immunized with the rE protein were significantly increased over that of Hyphantria cunea nuclear polyhedrosis virus E protein (HcE). Our results indicate that the rE protein expressed in the P. pastoris expression system holds great promise for use in the development of a subunit vaccine against JEV.

Purification and characterization of a novel angiotensin I-converting enzyme inhibitory peptide derived from an enzymatic hydrolysate of duck skin byproducts.

An angiotensin I-converting enzyme (ACE) inhibitory peptide was isolated and identified from hydrolysates of duck skin byproducts. Duck skin byproducts were hydrolyzed using nine proteases (Alcalase, Collagenase, Flavourzyme, Neutrase, papain, pepsin, Protamex, trypsin, and α-chymotrypsin) to produce an antihypertensive peptide. Of the various hydrolysates produced, the α-chymotrypsin hydrolysate exhibited the highest ACE inhibitory activity. The hydrolysate was purified using fast protein liquid chromatography (FPLC) and high-performance liquid chromatography (HPLC). The amino acid sequence of the ACE inhibitory peptide was identified as a hexapeptide Trp-Tyr-Pro-Ala-Ala-Pro, with a molecular weight of 693.90 Da. The peptide had an IC50 value of 137 µM, and the inhibitory pattern of the purified ACE inhibitor from duck skin byproducts was determined to be competitive by Lineweaver-Burk plots. In addition, the peptide was synthesized and the ACE inhibitory activity was verified in vivo. Spontaneously hypertensive rats (SHR) exhibited significantly decreased blood pressure and heart rate after peptide injection. Taken together, the results suggest that Trp-Tyr-Pro-Ala-Ala-Pro may be useful as a new antihypertensive agent.

Immunogenicity of Japanese encephalitis virus envelope protein by Hyphantria cunea nuclear polyhedrosis virus vector in guinea pig.

Japanese encephalitis virus (JEV) is an important pathogen causing febrile syndrome, encephalitis, and death. Envelop (E) glycoprotein is the major target of inducing neutralizing antibodies and protective immunity in host. In this study, E glycoprotein of JEV was expressed in Spodoptera frugiperd 9 cells as a fusion protein containing a gX signal sequence of pseudorabies virus. This purified HcE recombinant protein was evaluated for their immunogenicity and protective efficacy in guinea pig. The survival rates of guinea pig immunized with HcE protein was significantly increased over that of JE vaccine. This result indicates helpful information for developing a subunit vaccine against JEV.

Mechanism of activation of human c-KIT kinase by internal tandem duplications of the juxtamembrane domain and point mutations at aspartic acid 816.

The proto-oncogene c-KIT receptor has been implicated as an essential component in the activation of leukemic cells. The internal tandem duplication (ITD) of c-KIT has also been identified as a predominant cause of acute myeloid leukemia (AML), although its role in the activation process is still unclear. To investigate the biological mechanisms of c-KIT activation, we generated a c-KIT receptor bearing two different immunological tags, HA and Flag tags. In this study, we demonstrated that the mutant (Mt)-ITD and Asp816 (D816Y) c-KIT receptors spontaneously formed dimers and that these Mt-ITD forms of c-KIT displayed high levels of phosphorylation and increased cellular tyrosine phosphorylation. The amount of wild-type homodimers increased following the addition of the c-KIT ligand, while the level of mutant homodimers was less affected by the addition of the c-KIT ligand. Furthermore, we demonstrated that Mt-ITD and activating point mutations of D816Y induced constitutive activation of c-KIT kinase in the absence of ligand in COS-1 cells. These data suggest a novel mechanism for the regulation of cell growth autonomy. Overall, our study suggests that c-KIT activation might have significant effects on hematopoietic cells and might help to improve our understanding of the pathogenesis of systemic mast cell disease, gastrointestinal stromal tumors and AML and potentially lead to the development of novel therapeutic approaches.

A comparison of the immunostimulatory effects of the medicinal herbs Echinacea, Ashwagandha and Brahmi.

AIM OF THE STUDY: Herbs, as food or medicine, can strengthen the body and increase its resistance to illnesses by acting on various components of the immune system. For example, Echinacea is noted for its ability to enhance immune function, primarily through activation of the innate immune responses. Here, we investigated the potential for two herbs commonly found in India, Ashwagandha (Withania somnifera) and Brahmi (Bacopa monnieri), to enhance immune function and compared their effects to that of Echinacea. MATERIALS AND METHODS: Sprague Dawley rats were fed a diet supplemented with 1% (w/w) Echinacea, Ashwagandha, or Brahmi for 4 weeks to examine their effects on immune function. RESULTS: The Brahmi diet stimulated more secretion of IgA and IgG in the serum compared to Echinacea or Ashwagandha. Whether or not lectin was present in the diet, the production of IgA, IgG and IgM in spleen lymphocytes increased with herbal supplements. The concentrations of IFN-γ and IL-2 treated with LPS and ConA were significantly higher in the dietary herb than in the control. On the contrary, TNF-α production in rats receiving dietary herbal supplements was significantly lower compared to the control animals. CONCLUSION: Herbal remedies based on Echinacea, Brahmi, or Ashwagandha can enhance immune function by increasing immunoglobulin production. Furthermore, these herbal medicines might regulate antibody production by augmenting both Th1 and Th2 cytokine production.

Neuroprotective effects of a novel peptide purified from venison protein.

A novel antioxidative peptide (APVPH I, antioxidative peptides from venison protein hydrolysates I) was purified from venison by enzymatic hydrolysis, column chromatography of DEAE-Sephacel and high performance liquid chromatography. The molecular weight of the purified peptide was found to be 9,853 Da and the amino acid sequences of the purified peptide was Met-Gln-Ile-Phe-Val-Lys-Thr-Leu-Thr-Gly. The purpose of this study was to evaluate the effects of APVPH I against H2O2-induced neuronal cells damage in PC-12 cells. Antioxidative enzyme levels in cultured neuronal cells were increased in the presence of the peptide. In addition, APVPH I inhibited productions of nitric oxide (NO), reactive oxygen species (ROS), malondialdehyde (MDA) and cell death against H2O2-induced neuronal cells damage in PC-12 cells. It was presumed to be APVPH I involved in regulating the apoptosis-related gene expression in the cell environment. Present results indicate APVPH I substantially contribute to antioxidative properties in neuronal cells.

Diminished expression of dihydropteridine reductase is a potent biomarker for hypertensive vessels.

To identify the new targets for hypertension, we analyzed the protein expression profiles of aortic smooth muscle in spontaneously hypertensive rats (SHR) of various ages during the development of hypertension, as well as in age-matched normotensive Wistar-Kyoto (WKY) rats, using a proteomic analysis. The expressions of seven proteins were altered in SHR compared with WKY rats. Of these proteins, NADH dehydrogenase 1alpha, GSTomega1, peroxi-redoxin I and transgelin were upregulated in SHR compared with WKY rats. On the other hand, the expression of HSP27 and Ran protein decreased in SHR. The diminution of dihydrobiopterin reductase, an enzyme located in the regeneration pathways of tetrahydrobiopterin (BH4), was also prominent in SHR. The results from a PCR analysis revealed that the expression of BH4 biosynthesis enzymes - GTP cyclohydrolase-1 and sepiapterin reductase - decreased and increased, respectively, in SHR compared with WKY rats. The level of BH4 was less in aortic strips from SHR than from WKY rats. Moreover, treatment with BH4 inhibited aortic smooth muscle contraction induced by serotonin. These results suggest that the deficiency in BH4 regeneration produced by diminished dihydrobiopterin reductase expression is involved in vascular disorders in hypertensive rats.

Gene transfer of redox factor-1 inhibits neointimal formation: involvement of platelet-derived growth factor-beta receptor signaling via the inhibition of the reactive oxygen species-mediated Syk pathway.

The role of apurinic/apyrimidinic endonuclease-1/redox factor-1 (Ref-1) in vascular smooth muscle cells has yet to be clearly elucidated. Therefore, we attempted to determine the roles of Ref-1 in the migration induced by platelet-derived growth factor (PDGF)-BB and in its signaling in rat aortic smooth muscle cells (RASMCs). Cellular migration, superoxide (O(2)(-*)) production, Rac-1 activity, and neointima formation were determined in cells transfected with adenoviruses encoding for Ref-1 (AdRef-1) and small interference RNA of Ref-1. Overexpression of Ref-1 induced by treatment with RASMCs coupled with AdRef-1 inhibited the migration induced by PDGF-BB. PDGF-BB also increased the phosphorylation of the PDGFbeta receptor, spleen tyrosine kinase (Syk), mitogen-activated protein kinase, and heat shock protein 27, but these increases were significantly inhibited by AdRef-1 treatment. PDGF-BB increased O(2)(-*) production and Rac-1 activity, and these were diminished in cells transfected with AdRef-1. In contrast, RASMC migration, phosphorylation of Syk and O(2)(-*) production in response to PDGF-BB were increased by the knock down of Ref-1 with small interference RNA. The phosphorylation of PDGFbeta receptor in response to PDGF-BB was inhibited completely by the Syk inhibitor and was partly attenuated by a NADPH oxidase inhibitor. PDGF-BB increased the sprout outgrowth of the aortic ring ex vivo, which was inhibited in the AdRef-1-infected RASMCs as compared with the controls. Balloon injury-induced neointimal formation was significantly attenuated by the gene transfer of AdRef-1. These results indicate that Ref-1 inhibits the PDGF-mediated migration signal via the inhibition of reactive oxygen species-mediated Syk activity in RASMCs.

Antioxidant activity of enzymatic extracts from Stellaria dichotoma.

The antioxidant properties of enzymatic extracts from Stellaria dichotoma were evaluated using seven carbohydrases (Promozyme, Celluclast, Maltogenase, Viscozyme, Termamyl, Dextrozyme, and AMG 300L) and five proteases (Protamex, Flavourzyme, Neutrase, pancreatic trypsin, and Alcalase) (all from Novo Co., Novozyme Nordisk, Bagsvaerd, Denmark) for 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical, hydroxyl radical, and alkyl radical scavenging activity using an electron spin resonance spectrometer. The DPPH radical scavenging activities of pancreatic trypsin and Celluclast extracts from S. dichotoma were the highest among various protease and carbohydrate extracts, and the 50% inhibitory concentration (IC(50)) values were 10.45 and 13.80 microg/mL, respectively. The Flavourzyme and Promozyme extracts of S. dichotoma showed the highest hydroxyl radical scavenging activities among the tested protease and carbohydrase extracts, with IC(50) values of 1.51 and 1.23 microg/mL, respectively. The S. dichotoma enzymatic extracts also exhibited alkyl radical scavenging activity in a dose-dependent manner. In addition, the ability of the enzymatic extracts to inhibit the oxidative damage of DNA was assessed in vitro by measuring the conversion of supercoiled pBR322 plasmid DNA to the open circular form. It was found that the enzymatic extracts could significantly and dose-dependently protect against hydroxyl radical-induced DNA damage. These results indicate that enzymatic extracts of S. dichotoma possess potent antioxidant activity.

Soluble form of vascular cell adhesion molecule 1 induces migration and proliferation of vascular smooth muscle cells.

BACKGROUND: Serum levels of soluble vascular cell adhesion molecule 1 (sVCAM-1) shed from its membrane-bound form are elevated in hypertension. This study clarified the effects of sVCAM-1 on vascular responses in rat aortic smooth muscle cells (RASMCs). METHODS: Boyden chamber, 5-bromo-2'-deoxyuridine incorporation and ex vivo aortic ring assays for migration and proliferation, and Western blot for the kinase activity were used. RESULTS: Spontaneously hypertensive rats (SHR) and Wistar Kyoto (WKY) rats were compared functionally. sVCAM-1 increased RASMC migration and proliferation, which were greater in SHR compared with WKY rats. RASMCs expressed the very late antigen 4alpha receptor integrin with no difference between SHR and WKY rats. Inhibitors of phosphoinositide kinase 3 (PI3K) and spleen tyrosine kinase (Syk) and small interference RNA-Syk abolished the sVCAM-1-induced migration, proliferation and phosphorylation of focal adhesion kinase. The phosphorylation of Syk was significantly greater in RASMCs from SHR than from WKY rats. sVCAM-1 increased aortic sprout outgrowth, which was inhibited by inhibitors of PI3K and Syk. CONCLUSIONS: This study suggests that sVCAM-1 promotes the RASMC migration and proliferation via the focal adhesion kinase pathway regulated by Syk and PI3K, and the altered sVCAM-1-induced responses during hypertension are closely associated with the increments in intracellular signal transmission.

Contribution of soluble intercellular adhesion molecule-1 to the migration of vascular smooth muscle cells.

Soluble intercellular adhesion molecule-1 (sICAM-1), a circulating form of ICAM-1, has been known to be involved in the development of vascular diseases that are associated with vascular smooth muscle cell migration, such as hypertension and atherosclerosis. Here we investigated the contributions of sICAM-1 in promoting vascular migration in rat aortic smooth muscle cells (RASMCs). sICAM-1 increased RASMC migration, and this response was stronger in spontaneously hypertensive rats (SHRs) than in Wistar Kyoto (WKY) rats. The CD11a, CD11b, and CD18 subunits of ICAM-1 receptors were expressed in both SHRs and WKY rats; however, the expression levels of CD18 and CD11b were greater in SHRs than in WKY rats. The neutralization of the receptor subunits with anti-CD11a and -CD18 antibodies abolished the sICAM-1-increased migration. The treatment of inhibitors of spleen tyrosine kinase (Syk) and p38 mitogen-activated protein kinase suppressed the sICAM-1-stimulated migration of RASMCs. sICAM-1 also increased the sprout formation in aortic rings on Matrigel, and this response was inhibited by treatment with these inhibitors. The results suggest that sICAM-1 play crucial roles in vascular cell function through Syk pathways, and that the altered responses of sICAM-1 in RASMCs from SHRs may be mediated by the increased expression of the CD18 receptor.

p38 mitogen-activated protein kinase contributes to angiotensin II-stimulated migration of rat aortic smooth muscle cells.

In this study, we clarified the intracellular mechanism of angiotensin II (Ang II) in promoting migration in rat aortic smooth muscle cells (RASMCs). RASMC migration was measured with the Boyden chamber assay, and the result was confirmed with an aortic sprout assay. The activities of kinases were investigated by western blot analysis. Ang II enhanced RASMC migration, which was chemotaxis directed, and induced the phosphorylation of p38 mitogen-activated protein kinase (MAPK), extracellular signal-regulated kinase 1/2 (ERK1/2), and heat shock protein 27 (Hsp27). Ang II-enhanced cell migration was inhibited by SB203580 (a p38 MAPK inhibitor) and piceatannol (a spleen tyrosine kinase inhibitor), but only partially by PD98059 (an ERK inhibitor) and PP2 (a Src inhibitor). The Ang II-stimulated phosphorylation of p38 MAPK and Hsp27 in RASMCs was inhibited by piceatannol and SB203580. The phosphorylation of ERK1/2 stimulated by Ang II was suppressed by PD98059, piceatannol, and PP2. Ang II increased the sprout outgrowth from aortic rings and this response was attenuated by pretreatment with SB203580, PD98059, PP2, or piceatannol. These results suggest that p38 MAPK contributes to the regulation of the Ang II-induced chemotactic migration of vascular smooth muscle cells, which is mediated by Hsp27 phosphorylation.

Genome-wide examination of chromosomal aberrations in neuroblastoma SH-SY5Y cells by array-based comparative genomic hybridization.

Most neuroblastoma cells have chromosomal aberrations such as gains, losses, amplifications and deletions of DNA. Conventional approaches like fluorescence in situ hybridization (FISH) or metaphase comparative genomic hybridization (CGH) can detect chromosomal aberrations, but their resolution is low. In this study we used array-based comparative genomic hybridization to identify the chromosomal aberrations in human neuroblastoma SH-SY5Y cells. The DNA microarray consisting of 4000 bacterial artificial chromosome (BAC) clones was able to detect chromosomal regions with aberrations. The SH-SY5Y cells showed chromosomal gains in 1q12 approximately q44 (Chr1:142188905-246084832), 7 (over the whole chromosome), 2p25.3 approximately p16.3 (Chr2:18179-47899074), and 17q 21.32 approximately q25.3 (Chr17:42153031-78607159), while chromosomal losses detected were the distal deletion of 1p36.33 (Chr1:552910-563807), 14q21.1 approximately q21.3 (Chr14:37666271- 47282550), and 22q13.1 approximately q13.2 (Chr22:36885764-4190 7123). Except for the gain in 17q21 and the loss in 1p36, the other regions of gain or loss in SH-SY5Y cells were newly identified.

Cudraflavanone A, a flavonoid isolated from the root bark of Cudrania tricuspidata, inhibits vascular smooth muscle cell growth via an Akt-dependent pathway.

In previous studies of the root bark of Cudrania tricuspidata, various isoprenylated xanthones and flavonoids were isolated, some of which have anticancer, hepatoprotective, and antiperoxidative activities. Cytokines and growth factors are involved in the regulation of vascular smooth muscle cells (VSMCs) in atherosclerotic plaques. To assess whether cudraflavanone A isolated from the root bark of C. tricuspidata may be useful in the prevention of atherosclerosis or restenosis after angioplasty, we investigated the ability of cudraflavanone A to inhibit VSMCs growth under 25 ng/mL platelet-derived growth factor BB (PDGF-BB)-stimulated conditions. Cudraflavanone A (0.1-1 microM) significantly inhibited PDGF-BB-induced cell numbers in a concentration-dependent manner. The antigrowth effects of cudraflavanone A on VSMCs were also examined in [3H]-thymidine incorporation and cell cycle assays. Consistent with the inhibitory effect on cell number, PDGF-BB-stimulated [3H]-thymidine incorporation and cell cycle progression in VSMCs was also concentration-dependently reduced by cudraflavanone A. Furthermore, PDGF-BB markedly activated PDGF-beta receptor (PDGF-Rbeta) tyrosine kinase activity, leading to activation of intracellular signals required for VSMC growth. However, PDGF-BB-induced this kinase activity was not affected by cudraflavanone A. PDGF-BB also increased the activation of extracellular signal-regulated kinases 1 and 2 (ERK1/2), Akt, and phospholipase C gamma (PLCgamma)1, which are important signaling molecules in cell growth. Cudraflavanone A (0.1-1 microM) suppressed PDGF-BB-stimulated Akt activation, which is involved in cell survival, but had no effect on the activation of ERK1/2 and PLCgamma1. Selective modification of Akt activation by cudraflavanone A in VSMCs may suppress intimal thickening after angioplasty and plaque formation in atherosclerosis. These results suggest that cudraflavanone A from C. tricuspidata inhibits PDGF-BB-induced rat aortic VSMC growth via an Akt-dependent pathway.

Sulfated chitooligosaccharides as prolyl endopeptidase inhibitor.

Prolyl endopeptidase (PEP, EC 3.4.21.26) is a proline-specific endopeptidase with a serine-type mechanism, which digests small peptide-like hormones, neuroactive peptides, and various cellular factors. PEP has been involved in neurodegenerative disorders, therefore, the discovery of PEP inhibitors can revert memory loss caused by amnesic compounds. In this study, we prepared hetero-chitooligosaccharides (COSs) with different molecular sizes using ultrafiltration (UF) membrane reactor system from hetero-chitosan with different degrees of deacetylation (DD; 90%, 75% and 50% deacetylation), and synthesized sulfated COSs (SCOSs). PEP inhibitory activities of SCOSs were evaluated and the results showed that 50% deacetylated SCOSs (50-SCOSs) exhibited higher inhibitory activities than those of 90% and 75% deacetylated SCOSs (90-SCOSs and 75-SCOSs). Among the 50-SCOSs (50-SCOS I, 5000-10,000Da; 50-SCOS II, 1000-5000Da; 50-SCOS III, below 1000Da), 50-SCOS II possessed the highest inhibitory activity and IC(50) value was 0.38mg/ml. Kinetics studies with 50-SCOS II indicated a competitive enzyme inhibition with a K(i) value of 0.78mg/ml. It was concluded that the 50-SCOS II may be useful for PEP inhibitor and for developing a new type PEP inhibitor from carbohydrate based materials.

Syk contributes to PDGF-BB-mediated migration of rat aortic smooth muscle cells via MAPK pathways.

OBJECTIVE: Here we investigated the role of spleen tyrosine kinase (Syk) in the migration induced by platelet-derived growth factor (PDGF) in rat aortic smooth muscle cells (RASMC). METHODS: Cell migration was determined using a Boyden chamber, by wound-healing, and by aortic ring assays. Activity of Syk, mitogen-activated protein kinase (MAPK), and heat shock protein 27 (HSP27) were tested using immunoblotting with kinase inhibitors and small interference RNAs. RESULTS: PDGF-BB induced binding of Syk to the PDGFbeta receptor and increased the phosphorylation of Syk and migration in RASMC. These effects of PDGF-BB were inhibited by piceatannol, an inhibitor of Syk. PDGF-BB increased the phosphorylation of extracellular signal-regulated kinase (ERK) 1/2, p38 MAPK, and HSP27, which were significantly inhibited by piceatannol and in Syk-knockdown cells. The p38 MAPK inhibitor SB203580 and ERK1/2 inhibitor PD98059 inhibited the migration, which was further inhibited by the combination of these inhibitors. SB203580, but not PD98059, inhibited the phosphorylation of HSP27 induced by PDGF-BB in RASMC. PDGF-BB-induced migration was attenuated in HSP27-knockdown cells. Kinase inhibitors and Syk-knockdown diminished PDGF-BB-induced sprout outgrowth in the aortic ring assay. CONCLUSIONS: These results imply that Syk is an upstream signal of the p38 MAPK/HSP27 and ERK1/2 pathways that contributes to PDGF-BB-mediated migration in RASMC.

Phorbol ester-induced contraction through p38 mitogen-activated protein kinase is diminished in aortas from DOCA-salt hypertensive rats.

The role of mitogen-activated protein kinase (MAPK) in the decreased contractile response to phorbol ester in aortic smooth muscle strips from deoxycorticosterone acetate (DOCA)-salt hypertensive rats was examined. Norepinephrine (NE) evoked greater contractility in aortic strips from DOCA rats than in those of sham-operated rats. 12-Deoxyphorbol 13-isobutyrate (DPB) induced contraction in Ca2+-free medium, which was diminished in strips from DOCA rats compared to sham-operated rats. Vasoconstrictions induced by these stimulants were inhibited by SB203580 and PD098059, inhibitors of p38 MAPK and extracellular signal-regulated kinase (ERK) 1/2, respectively, in both strips. The phosphorylation of p38 MAPK and ERK1/2 induced by NE was greater in strips from DOCA rats compared to those from sham-operated rats, and this phosphorylation was inhibited by the kinase inhibitors. DPB increased the phosphorylation of p38 MAPK and ERK1/2 in strips from both animals, and the increment of p38 MAPK phosphorylation by the stimulant was diminished in strips from DOCA rats compared to sham-operated rats. These findings suggest that the Ca2+-independent contraction evoked by DPB results from the activation of MAPKs in rat aortic smooth muscle and that the attenuated contractility by DPB in DOCA rat appears to be associated with diminished p38 MAPK activity.