α_(1A)-adrenergic receptor mediated pressor response to phenylephrine in anesthetized rat

To determine which subtype of α1-adrenergic receptors plays a role in the regulation of blood pressure, with α1A-adrenergic receptor-mediated vasoconstriction in perfused hindlimb as a control, we compared the inhibitory effects of various ai-adrenergic receptor selective antagonists on the vasopressure responses to phenylephrine between the mean arterial pressure and hindlimb perfusion pressure in anesthetized rats. In Normotensive Wistar rats, the results showed that the inhibitory effects (dose ratios of ED50, Dr) of α1-adrenoceptor selective antagonist (prazosin, Dr 13.5±3.6 vs.15.1±4.3, n = 11), α1A-adrenoceptor selective antagonist (5-methyl-urapidil, Dr 2.4±0.9 vs. 3.7±2.3, n = 12; RS-17053, Dr 3.2±1.6 vs. 4.4±3.3, n =12) and α1D-adrenoceptor selective antagonist (BMY7378, Dr 1.9±0.9 vs. 2.2±0.8, n = 8) on phenylephrine- induced increases of perfusion pressure in the autoperfused femoral beds were the same as that in the mean arterial blood pressure in normotensive Wistar rats. The i     

Identification of γ_1 subunit of GABA_A receptor in rat testis

INTRODUCTIONry-Aminobutyric acid (GABA) is the predomi-nant inhibitory neurotransmitter in the vertebratecentral nervous system (CNS)[1]. Whereas outsidethe CNS, many peripheral tissues have also beenfOund to have GABAergic system[2].The mammalian sperm acrosome reaction (AR)is a modified exocytotic event that is essential to thefertilization process[3]. Two main agOnists of AR,the zona pellucida glycoprotein ZP3[4] and proges-terone[5], have been identified in the oocyte vest-me…     

Adenovirus-mediated expression of pig α(1,3) galactosyltransferase reconstructs Gal α(1,3) Gal epitope on the surface of human tumor cells

INTRODUCTIONGal a(1, 3) Gal (gal epitope) is a carbohydrate epitope, which is produced in large amounton the cells of pigs, mice and New World monkey(monkey of South America) by the glycosylationenzyme G alal 1 ) 4G IcNAc3- a- D- galactosyltransferase[or(1, 3)GT; EC2.4.1.511111. This enzyme is active in the Golgi appaxatus of cells and transfers galactose from the sugandonor uridine diphoSphate galactose (UDP-galactose) to the acceptor Nacetyllactosamine residue (Galaal-4GlcNAc-R…     

PLD activation in Chinese hamster ovary (CHO) cells transfected with PGF2α receptor cDNA

Pertussis toxin-insensitive GTP-binding protein was observed to be involved in prostaglandin F2α(PGF2α)-induced phosphoinositide metabolism in Chinese hamster ovary (CHO) cells transfected with PGF2α receptor cDNA (CHO-PGF2α·R cells) (Ito, S. et al. Biochem. Biophys. Res. Commun. 200: 756, 1994). In the present study, we investigated PGF2α-induced PLD activation in CHO-PGF2α·R cells. PLD activation was examined by measuring the production of [³H]phosphatidylbutanol ([³H]PBut), a specific product of the PLD-catalyzed transphosphatidylation reaction. PGF2α-induced [³H]PBut formation was concentration-dependent with the maximal level obtained at 1 μM PGF2α. The maximal [³H]PBut formation was observed at 2 min after addition of PGF2α. Depletion of extracellular Ca²⁺ with EGTA suppressed PGF2α-induced PLD activation by 50%. PKC inhibitors Ro31–8425 and calphostin C inhibited PGF2α-induced [³H]PBut formation by 50%. PTK inhibitors genistein and herbimycin A failed to inhibit PGF2α-induced PLD activation. A combination of maximal effective concentrations of PGF2α (1 μM) and PMA (100 nM) enhanced PLD activation in an additive manner. Pretreatment of the cells with PMA for 2 h down-regulated PKCα and decreased PGF2α-induced PLD activation. These results suggest that PLD activation by PGF2α is mediated by both PKC-dependent and -independent pathways and that PKCα is involved in the former pathway.     

Expression of human transforming growth factor β1 in E. coli (I) --Direct expression in cytoplasm

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Microcystin-LR (MCLR) induces a compensation of PP2A activity mediated by α4 protein in HEK293 cells

Protein phosphatase 2A (PP2A) is a major protein phosphatase with important cell functions. Known and utilized as a potent inhibitor of PP2A, microcystin-LR (MCLR) targets PP2A as a core element that affects numerous cellular mechanisms. But apart from direct inhibition, the exact effect of MCLR on PP2A in cell is largely unknown, specifically with regard to cellular response and autoregulation. Here, we show that a low concentration of MCLR stimulates, rather than inhibits, PP2A activity in HEK293 cells. Immunoprecipitation and immunofluorescence assays reveal that the catalytic subunit and a regulatory subunit of PP2A, termed α4, dissociate from inactive complex upon MCLR exposure, suggesting that the released catalytic subunit regains activity and thereby compensates the activity loss. At high concentrations of MCLR, PP2A activity decreases along with dissociation of the core enzyme and altered post-translational modification of its catalytic subunit. In addition, the dissociation of α4 and PP2A may contribute to destabilization of HEK293 cells cytoskeleton architecture, detachment to extracellular matrix and further anoikis. Our data provide a novel PP2A upregulation mechanism and challenge the recognition of MCLR only as a PP2A inhibitor in cells.     

Active expression of Gγ globin gene on chromosome 11 with Yunnanese (Ayγδβ)~0-thalasseinia deletion in MEL cells

A permanent lymphocyte cell line of a heterozygote with Yunnanese (Aγδβ)0-thalassemia deletion, associated with an increased production of Cry globin in adult, was founded using Epstein-Barr virus transformation. The hybrids of the lymphocyte cell and mouse erythroleukemia cell (MEL) were achieved and the hybrids containing human chromosome 11 were selected with the monoclonal antibody 53/6. The subclones containing only either the normal or the abnormal human chromosome 11 were separated and the expression of the human globin genes was studied. Expression of the β-globin gene, but not the Cγ and Aγ, was observed in the hybrids containing only the normal human chromosome 11, while active expression of the Cγ globin gene was observed in the hybrids containing only the abnormal human chromosome 11. These results have confirmed that the DNA deletion in the β-globin gene cluster is the cause of persistent active expression of the Cγ globin gene in the Yunnanese mutant.     

Arylsulfonamide derivatives of (aryloxy)ethyl pyrrolidines and piperidines as α1-adrenergic receptor antagonist with uro-selective activity

A series of arylsulfonamide derivatives of (aryloxy)ethyl pyrrolidines and piperidines was synthesized to develop new α₁-adrenoceptor antagonists with uroselective profile. Biological evaluation for α₁- and α₂-adrenorecepor showed that tested compounds 13–37 displayed high-to-moderate affinity for the α₁-adrenoceptor (K_i = 34–348 nM) and moderate selectivity over α₂-receptor subtype. Compounds with highest affinity and selectivity for α₁-adrenoceptor were evaluated in vitro for their intrinsic activity toward α_1A- and α_1B-adrenoceptor subtypes. All compounds behaved as antagonists at both α₁-adrenoceptor subtypes, displaying 2- to 6-fold functional preference to α_1A-subtype. Among them, N-{1-[2-(2-methoxyphenoxy)ethyl]piperidin-4-yl}isoquinoline-4-sulfonamide (25) and 3-chloro-2-fluoro-N-{[1-(2-(2-isopropoxyphenoxy)ethyl)piperidin-4-yl]methyl}benzene sulfonamide (34) displayed the highest preference to α_1A-adrenoceptor. Finally, compounds 25 and 34 (2–5 mg/kg, iv), in contrast to tamsulosin (1–2 mg/kg, iv), did not significantly decrease systolic and diastolic blood pressure in normotensive anesthetized rats to determine their influence on blood pressure.     

Identification of a NF-кB site in the negative regulatory element (ε-NRAII) of human ε-globin gene and its binding protein NF-кB p50 in the nuclei of K562 cells

INTRODUCTIONThe human P-like globin genes are arranged as acluster of five genes(e, Gry, Ary, 8 and P) in the orderof their temporal expression. The human embryonicE-globin gene is expressed in the blood island of theembryonic yolk sac and is silenced completely at 6~8w of gestation in the fetal liverI11. Studies on trans-genic mice suggested that the regulation of 5-globingene expression is autonomous. The activating andsilencing of 5-globin gene expression rely on distallocus control …     

Effects of adeno-associated virus (AAV) of transforming growth factors β_1 and β_3 (TGFβ_(1,3)) on promoting synthesis of glycosaminoglycan and collagen type II of dedifferentiated nucleus pulposus (NP) cells

The effects of AAV-TGFβ1 and AAV-TGFβ3 on promoting synthesis of glycosaminoglycan and collagen type II of dedifferentiated rabbit lumbar disc NP cells were studied in this work. The rabbit lumbar disc NP cells were isolated and cultured. The earlier and later dedifferentiated NP cells were established by subculture. The AAV transfection efficiency to dedifferentiated NP cells was analyzed with AAV-EGFP in vitro. After dedifferentiated NP cells were transfected by AAV-TGFβ1 or AAV-TGFβ3, their biological effects on promoting synthesis of glycosaminoglycan or collagen type II were detected and compared by the methods of 35S incorporation or immunoblotting. The experimental results showed that AAV could transfect efficiently the earlier dedifferentiated NP cells, but its transfection rate was shown to be at a low level to the later dedifferentiated NP cells. Both AAV-TGFβ1 and AAV-TGFβ3 could promote the earlier dedifferentiated NP cells to synthesize glycosaminoglycan and collagen type II, and the effect of AAV-TGFβ1 was better than that of AAV-TGFβ3. For the later dedifferentiated NP cells, the AAV-TGFβ3 could promote their synthesis, but AAV-TGFβ1 could slightly inhibit their synthesis. Therefore, AAV-TGFβ1 and AAV-TGFβ3 could be used for the earlier dedifferentiated NP cells, and the TGFβ3 could be used as the objective gene for the later dedifferentiated NP cells.     

Evaluation of 3,4-dihydroquinazoline-2(1H)-thiones as inhibitors of α-MSH-induced melanin production in melanoma B16 cells

Novel 3,4-dihydroquinazoline-2(1H)-thiones (QNTs) 1 were found to be potent inhibitors of α-MSH-induced melanin production. The effect of QNTs to inhibit melanin formation in B16 melanoma cells was screened in the presence of α-MSH. In defining the mechanism of activity, the effects on tyrosinase activity, on tyrosinase synthesis and on the depigmentation of melanin were evaluated. QNTs did not affect the catalytic activity of tyrosinase, but rather acted as an inhibitor of tyrosinase synthesis.     

The influence of monovalent cations on trimeric G protein G(i)1α activity in HEK293 cells stably expressing DOR-G(i)1α (Cys(351)-Ile(351)) fusion protein

The effect of monovalent cations on trimeric G protein G(i)1α was measured at equimolar concentration of chloride anion in pertussis-toxin (PTX)-treated HEK293 cells stably expressing PTX-insensitive DOR- G(i)1α (Cys(351)-Ile(351)) fusion protein by high-affinity [(35)S]GTPgammaS binding assay. The high basal level of binding was detected in absence of DOR agonist and monovalent ions and this high level was inhibited with the order of: Na(+) > K(+) > Li(+). The first significant inhibition was detected at 1 mM NaCl. The inhibition by monovalent ions was reversed by increasing concentrations of DOR agonist DADLE. The maximum DADLE response was also highest for sodium and decreased in the order of: Na(+) > K(+) ~ Li(+). Our data indicate i) an inherently high activity of trimeric G protein G(i)1α when expressed within DOR- G(i)1α fusion protein and determined in the absence of monovalent cations, ii) preferential sensitivity of DOR- G(i)1alpha to sodium as far as maximum of agonist response is involved.     

3-Formylchromone interacts with cysteine 38 in p65 protein and with cysteine 179 in IκBα kinase, leading to down-regulation of nuclear factor-κB (NF-κB)-regulated gene products and sensitization of tumor cells

3-Formylchromone (3-FC) has been associated with anticancer potential through a mechanism yet to be elucidated. Because of the critical role of NF-κB in tumorigenesis, we investigated the effect of this agent on the NF-κB activation pathway. Whether activated by inflammatory agents (such as TNF-α and endotoxin) or tumor promoters (such as phorbol ester and okadaic acid), 3-FC suppressed NF-κB activation. It also inhibited constitutive NF-κB expressed by most tumor cells. This activity correlated with sequential inhibition of IκBα kinase (IKK) activation, IκBα phosphorylation, IκBα degradation, p65 phosphorylation, p65 nuclear translocation, and reporter gene expression. We found that 3-FC inhibited the direct binding of p65 to DNA, and this binding was reversed by a reducing agent, thus suggesting a role for the cysteine residue. Furthermore, mutation of Cys38 to Ser in p65 abolished this effect of the chromone. This result was confirmed by a docking study. 3-FC also inhibited IKK activation directly, and the reducing agent reversed this inhibition. Furthermore, mutation of Cys179 to Ala in IKK abolished the effect of the chromone. Suppression of NF-κB activation led to inhibition of anti-apoptotic (Bcl-2, Bcl-xL, survivin, and cIAP-1), proliferative (cyclin D1 and COX-2), invasive (MMP-9 and ICAM-1), and angiogenic (VEGF) gene products and sensitization of tumor cells to cytokines. Thus, this study shows that modification of cysteine residues in IKK and p65 by 3-FC leads to inhibition of the NF-κB activation pathway, suppression of anti-apoptotic gene products, and potentiation of apoptosis in tumor cells.     

Induction of intracellular calcium concentration by environmental benzo(a)pyrene involves a β2-adrenergic receptor/adenylyl cyclase/Epac-1/inositol 1,4,5-trisphosphate pathway in endothelial cells

Polycyclic aromatic hydrocarbons (PAHs) such as benzo(a)pyrene (B(a)P) are widely distributed environmental contaminants, known as potent ligands of the aryl hydrocarbon receptor (AhR). These chemicals trigger an early and transient increase of intracellular calcium concentration ([Ca(2+)](i)), required for AhR-related effects of PAHs. The mechanisms involved in this calcium mobilization were investigated in the present study. We demonstrated that B(a)P-mediated [Ca(2+)](i) induction was prevented in endothelial HMEC-1 cells by counteracting β2-adrenoreceptor (β2ADR) activity using pharmacological antagonists, anti-β2ADR antibodies, or siRNA-mediated knockdown of β2ADR expression; by contrast, it was strongly potentiated by β2ADR overexpression in human kidney HEK293 cells. B(a)P was shown, moreover, to directly bind to β2ADR, as assessed by in vitro binding assays and molecular modeling. Pharmacological inhibition and/or siRNA-mediated silencing of various signaling actors acting downstream of β2ADR in a sequential manner, such as G protein, adenylyl cyclase, Epac-1 protein, and inositol 1,4,5-trisphosphate (IP(3))/IP(3) receptor, were next demonstrated to prevent B(a)P-induced calcium signal. Inhibition or knockdown of these signaling elements, as well as the use of chemical β-blockers, were finally shown to counteract B(a)P-mediated induction of cytochrome P-450 1B1, a prototypical AhR target gene. Taken together, our results show that B(a)P binds directly to β2ADR and consequently utilizes β2ADR machinery to mobilize [Ca(2+)](i), through activation of a G protein/adenylyl cyclase/cAMP/Epac-1/IP(3) pathway. This β2ADR-dependent signaling pathway activated by PAHs may likely be crucial for PAH-mediated up-regulation of AhR target genes, thus suggesting a contribution of β2ADR to the health-threatening effects of these environmental pollutants.     

Macrophage inflammatory protein-1α (MIP-1α) enhances a receptor activator of nuclear factor κB ligand (RANKL) expression in mouse bone marrow stromal cells and osteoblasts through MAPK and PI3K/Akt pathways

Osteolytic lesions are rapidly progressive during the terminal stages of myeloma, and the bone pain or bone fracture that occurs at these lesions decreases the patients’ quality of life to a notable degree. In relation to the etiology of this bone destruction, it has been reported recently that MIP-1α, produced in large amounts in myeloma patients, acts indirectly on osteoclastic precursor cells, and activates osteoclasts by way of bone-marrow stromal cells or osteoblasts, although the details of this process remain obscure. In the present study, our group investigated the mechanism by which RANKL expression is induced by MIP-1α and the effects of MIP-1α on the activation of osteoclasts. RANKL mRNA and RANKL protein expressions increased in both ST2 cells and MC3T3–E1 cells in a MIP-1α concentration-dependent manner. RANKL mRNA expression began to increase at 1 h after the addition of MIP-1α; the increase became remarkable at 2 h, and continuous expression was observed subsequently. Both ST2 and MC3T3-E1 cells showed similar levels of increased RANKL protein expression at 1, 2, and 3 days after the addition of MIP-1α. After the addition of MIP-1α, the amount of phosphorylated ERK1/2 and Akt protein expressions showed an increase, as compared to the corresponding amount in the control group. On the other hand, the amount of phosphorylated p38MAPK protein expression showed a decrease from the amount in the control group after the addition of MIP-1α. U0126 (a MEK1/2 inhibitor) or LY294002 (a PI3K inhibitor) was added to ST2 and MC3T3-E1 cells, and was found to inhibit RANKL mRNA and RANKL protein expression in these cells. When SB203580, a p38MAPK inhibitor, was added, RANKL mRNA and RANKL protein expression were increased in these cells. MIP-1α was found to promote osteoclastic differentiation of C7 cells, an osteoclastic precursor cell line, in a MIP-1α concentration-dependent manner. MIP-1α promoted differentiation into osteoclasts more extensively in C7 cells incubated together with ST2 and MC3T3-E1 cells than in C7 cells incubated alone. These results suggested that MIP-1α directly acts on the osteoclastic precursor cells and induces osteoclastic differentiation. This substance also indirectly induces osteoclastic differentiation through the promotion of RANKL expression in bone-marrow stromal cells and osteoblasts. The findings of this investigation suggested that activation of the MEK/ERK and the PI3K/Akt pathways and inhibition of p38MAPK pathway were involved in RANKL expression induced by MIP-1α in bone-marrow stromal cells and osteoblasts. This finding may be useful in the development of an osteoclastic inhibitor that targets intracellular signaling factors.