RESUMO
The co-mitogenic effects of the α1-adrenoceptor agonist phenylephrine on S-allyl-L-cysteine (SAC)-induced hepatocyte proliferation were examined in primary cultures of adult rat hepatocytes. The combination of phenylephrine (10-10-10-6 M) and SAC (10-6 M) exhibited a significant dose-dependent increase in the number of hepatocyte nuclei and viable cells compared to SAC alone. This combination also increased the progression of hepatocyte nuclei into the S-phase. The potentiating effect of phenylephrine on SAC-induced cell proliferation was counteracted by prazosin (an α1-adrenergic receptor antagonist) and GF109203X (selective protein kinase C (PKC) inhibitor). In addition, PMA (direct PKC activator) potentiated the proliferative effects of SAC similarly to phenylephrine. In essence, these findings suggest that PKC activity plays a crucial role in enhancing SAC-induced cell proliferation. Moreover, the effects of phenylephrine on SAC-induced Ras activity, Raf phosphorylation, and extracellular signal-regulated kinase 2 (ERK2) phosphorylation were investigated. Phenylephrine (or PMA) in combination with SAC did not augment Ras activity, but further increased ERK2 phosphorylation and its upstream B-Raf phosphorylation. These results indicate that PKC activation, triggered by stimulating adrenergic α1 receptors, further amplifies SAC-induced cell proliferation through enhanced ERK2 phosphorylation via increased B-Raf-specific phosphorylation in primary cultured hepatocytes.
Assuntos
Agonistas de Receptores Adrenérgicos alfa 1 , Proliferação de Células , Cisteína , Hepatócitos , Fenilefrina , Proteína Quinase C , Proteínas Proto-Oncogênicas B-raf , Animais , Fenilefrina/farmacologia , Hepatócitos/efeitos dos fármacos , Hepatócitos/metabolismo , Proteína Quinase C/metabolismo , Cisteína/farmacologia , Cisteína/análogos & derivados , Fosforilação/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Células Cultivadas , Agonistas de Receptores Adrenérgicos alfa 1/farmacologia , Masculino , Proteínas Proto-Oncogênicas B-raf/metabolismo , Prazosina/farmacologia , Acetato de Tetradecanoilforbol/farmacologia , Acetato de Tetradecanoilforbol/análogos & derivados , Proteína Quinase 1 Ativada por Mitógeno/metabolismo , Maleimidas/farmacologia , Ratos , Indóis/farmacologia , Antagonistas de Receptores Adrenérgicos alfa 1/farmacologia , Sinergismo Farmacológico , Ratos Sprague-Dawley , Mitógenos/farmacologiaRESUMO
The cell proliferation effect of S-allyl-L-cysteine (SAC) and its mechanisms were examined in primary cultures of adult rat hepatocytes. In serum-free cultivation, SAC (10-6 M)-stimulated hepatocytes showed significant proliferation compared to control at 5-h culture; the effect was dependent on the culture time and the dose of SAC (EC50 value 8.58 × 10-8 M). In addition, SAC-stimulated hepatocytes significantly increased mRNA expression levels of c-Myc and c-Fos at 1 h and cyclin B1 at 3.5 and 4 h, respectively. In contrast, alliin and allicin, structural analogs of SAC, did not show these effects observed with SAC. The SAC-induced hepatocyte proliferation effects were completely suppressed by monoclonal antibodies against growth hormone receptor and insulin-like growth factor type-I (IGF-I) receptor, respectively. Furthermore, the Janus kinase 2 (JAK2) inhibitor TG101209, phospholipase C (PLC) inhibitor U-73122, IGF-I receptor tyrosine kinase (RTK) inhibitor AG538, PI3 kinase inhibitor LY294002, MEK inhibitor PD98059, and mTOR inhibitor rapamycin completely suppressed the SAC-induced hepatocyte proliferation. JAK2 (p125 kDa) phosphorylation in cultured hepatocytes peaked 5 min after SAC stimulation. SAC-induced IGF-I RTK (p95 kDa) and ERK2 (p42 kDa) phosphorylation had slower rises than JAK2, peaking at 20 and 30 min, respectively. These results indicate that SAC promoted cell proliferation by growth hormone receptor/JAK2/PLC pathway activation followed by activation of the IGF-I RTK/PI3K/ERK2/mTOR pathway in primary cultures of adult rat hepatocytes.
Assuntos
Cisteína/análogos & derivados , Hepatócitos , Fator de Crescimento Insulin-Like I , Janus Quinase 2 , Proteína Quinase 1 Ativada por Mitógeno , Receptor IGF Tipo 1 , Animais , Proliferação de Células/efeitos dos fármacos , Cisteína/farmacologia , Hepatócitos/citologia , Hepatócitos/efeitos dos fármacos , Hepatócitos/enzimologia , Hepatócitos/metabolismo , Fator de Crescimento Insulin-Like I/metabolismo , Fator de Crescimento Insulin-Like I/farmacologia , Janus Quinase 2/metabolismo , Proteína Quinase 1 Ativada por Mitógeno/metabolismo , Fosfatidilinositol 3-Quinases/metabolismo , Fosforilação/efeitos dos fármacos , Cultura Primária de Células , Ratos , Receptor IGF Tipo 1/metabolismo , Receptores da Somatotropina/metabolismo , Serina-Treonina Quinases TOR/metabolismoRESUMO
The mechanism of insulin-like growth factor type-I (IGF-I) secretion stimulated by S-allyl-L-cysteine (SAC) was investigated as part of a study of SAC-induced DNA synthesis and cell proliferation in primary cultures of adult rat hepatocytes. When 10-6 M SAC was added to the culture, the amount of IGF-I in the medium was significantly increased at 10 min. The peak IGF-I level (140 pg/mL) was observed 20 min after SAC stimulation. The SAC-induced IGF-I secretion was completely suppressed by a selective Janus kinase 2 (JAK2) inhibitor (TG101209), a selective phospholipase C (PLC) inhibitor (U-73122), an intracellular Ca2+ chelating agent (BAPTA-AM), and a granule secretion inhibitor (somatostatin). On the other hand, 10-6 M SAC-stimulated hepatocytes showed increased intracellular Ca2+ concentration in a time-dependent manner from 0 to 10 min. Phosphorylation of SAC-induced JAK2 and IGF-I receptor tyrosine kinase (RTK) was completely suppressed by TG101209. In addition, U-73122, BAPTA-AM, and somatostatin did not suppress SAC-induced JAK2 phosphorylation, but significantly suppressed SAC-induced IGF-I RTK phosphorylation. Furthermore, binding of the monoclonal antibody against growth hormone (GH) to GH receptor was dose-dependently suppressed by SAC on immunofluorescence. These results showed that SAC promotes cell proliferation by stimulating GH receptor/JAK2/phospholipase C pathways and promoting autocrine secretion of IGF-I in primary cultures of adult rat hepatocytes.
Assuntos
Fator de Crescimento Insulin-Like I , Receptores da Somatotropina , Animais , Proliferação de Células , Cisteína/metabolismo , Hepatócitos/metabolismo , Fator de Crescimento Insulin-Like I/metabolismo , Fator de Crescimento Insulin-Like I/farmacologia , Janus Quinase 2/metabolismo , Ratos , Receptores da Somatotropina/metabolismo , Somatostatina/metabolismo , Fosfolipases Tipo CRESUMO
Two-thirds partial hepatectomy (PHx) was performed in rats, and the differences in effects between S-allylcysteine (SAC) and other sulfur-containing compounds on regeneration of the remaining liver and restoration of the injury were examined. Three days after two-thirds PHx, rats treated with 300 mg/kg/d, per os (p.o.) SAC showed a 1.2-fold increase in liver weight per 100 g body weight compared with saline-treated controls. In contrast, S-methylcysteine (SMC) (300 mg/kg/d, p.o.) or cysteine (Cys) (300 mg/kg/d, p.o.) did not have a regeneration-promoting effect. In the comparison with control rats, the regenerating liver of SAC-treated rats showed a significantly higher 5-bromo-2'-deoxyuridine labeling index on day 1. In contrast, serum alanine aminotransferase activity, which increases following PHx, was significantly inhibited by SAC and SMC (but not Cys) on day 1 after two-thirds PHx. In addition, SAC induced increases in insulin-like growth factor (IGF)-1 and its receptor mRNA expressions at 1 h after two-thirds PHx, and it increased phosphorylation of extracellular signal-regulated kinase (ERK)2 and Akt at 3 h after two-thirds PHx without affecting serum growth hormone levels. These results demonstrate that SAC is a mitogenic effector of normal remnant liver and promotes recuperation of liver function after two-thirds PHx. Moreover, SAC-induced proliferative effects are mediated via increased mRNA expressions of IGF-1 and its receptor and subsequent phosphorylation of ERK2 and Akt.
Assuntos
Cisteína/análogos & derivados , Fator de Crescimento Insulin-Like I/genética , Regeneração Hepática/efeitos dos fármacos , Fígado/efeitos dos fármacos , Receptor IGF Tipo 1/genética , Animais , Proliferação de Células/efeitos dos fármacos , Proliferação de Células/genética , Cisteína/administração & dosagem , Hepatectomia , Fígado/cirurgia , Regeneração Hepática/genética , Masculino , Proteína Quinase 1 Ativada por Mitógeno/metabolismo , Modelos Animais , Fosforilação/efeitos dos fármacos , Proteínas Proto-Oncogênicas c-akt/metabolismo , RNA Mensageiro/metabolismo , Ratos , Ratos WistarRESUMO
Serotonin (5-hydroxytryptamine; 5-HT) can induce hepatocyte DNA synthesis and proliferation by autocrine secretion of transforming growth factor (TGF)-α through 5-HT2B receptor/phospholipase C (PLC)/Ca2+ and a signaling pathway involving epidermal growth factor (EGF)/TGF-α receptor tyrosine kinase (RTK)/extracellular signal-regulated kinase 2 (ERK2)/mammalian target of rapamycin (mTOR). In the present study, we investigated whether 5-HT or a selective 5-HT2B receptor agonist BW723C86, would stimulate phosphorylation of TGF-α RTK and ribosomal p70 S6 kinase (p70S6K) in primary cultures of adult rat hepatocytes. Western blotting analysis was used to detect 5-HT- or BW723C86 (10-6 M)-induced phosphorylation of EGF/TGF-α RTK and p70S6K. Our results showed that 5-HT- or BW723C86 (10-6 M)-induced phosphorylation of EGF/TGF-α RTK peaked at between 5 and 10 min. On the other hand, 5-HT- or BW723C86 (10-6 M)-induced phosphorylation of p70S6K peaked at about 30 min. Furthermore, a selective 5-HT2B receptor antagonist LY272015, a specific PLC inhibitor U-73122, a membrane-permeable Ca2+ chelator BAPTA/AM, an L-type Ca2+ channel blocker verapamil, somatostatin, and a specific p70S6K inhibitor LY2584702 completely abolished the phosphorylation of p70S6K induced by both 5-HT and BW723C86. These results indicate that phosphorylation of p70S6K is dependent on the 5-HT2B-receptor-mediated autocrine secretion of TGF-α. In addition, these results demonstrate that the hepatocyte proliferating action of 5-HT and BW723C86 are mediated by phosphorylation of p70S6K, a downstream element of the EGF/TGF-α RTK signaling pathway.
Assuntos
Receptores ErbB/metabolismo , Hepatócitos/efeitos dos fármacos , Indóis/farmacologia , Receptor 5-HT2B de Serotonina/metabolismo , Proteínas Quinases S6 Ribossômicas 70-kDa/metabolismo , Agonistas do Receptor 5-HT2 de Serotonina/farmacologia , Tiofenos/farmacologia , Animais , Proliferação de Células/efeitos dos fármacos , Células Cultivadas , Hepatócitos/metabolismo , Masculino , Fosforilação , Cultura Primária de Células , Ratos WistarRESUMO
Polycationic compounds, such as poly-L-arginine and poly-L-ornithine (PLO), enhance the nasal absorption of hydrophilic macromolecular drugs. However, the bio availability corresponding to the dose of these enhancers has not been obtained in an open system study, where an administered solution is transferred to the pharynx because they do not exhibit mucoadhesion/retention in the nasal cavity. In this study, we prepared PEGylated-poly-L-ornithine (PEG-PLO) and investigated the effects of PEGylation on in vitro adhesion/retention properties, permeation enhancement efficiency, and cytotoxicity. PEG-PLO bearing 3-4 polyethylene glycol (PEG) chains per PLO molecule was more retentive than unmodified PLO on an inclined plate. The permeability of a model drug, FD-4, across Caco-2 cell sheets was enhanced by PEG-PLO as well as by PLO. PLO showed cytotoxicity at high concentrations, whereas PEG-PLO did not decrease cell viability, even above the concentration giving a sufficient enhancement effect. These findings suggest that PEGylation of polycationic absorption enhancers improves their adhesion/retention and decreases their cytotoxicity, which may lead to enhancers with greater utility.
Assuntos
Absorção Gastrointestinal/fisiologia , Peptídeos/metabolismo , Polietilenoglicóis/metabolismo , Tensoativos/metabolismo , Células CACO-2 , Sobrevivência Celular/efeitos dos fármacos , Sobrevivência Celular/fisiologia , Avaliação Pré-Clínica de Medicamentos/métodos , Absorção Gastrointestinal/efeitos dos fármacos , Humanos , Peptídeos/síntese química , Peptídeos/farmacologia , Polietilenoglicóis/síntese química , Polietilenoglicóis/farmacologia , Tensoativos/síntese química , Tensoativos/farmacologiaRESUMO
We have already reported that poly-L-arginine (PLA) remarkably enhanced the in vivo nasal absorption of hydrophilic macromolecules without producing any significant epithelial damage in rats. In the present study, we examined whether PLA could enhance the absorption of a model hydrophilic macromolecule, fluorescein isothiocyanate-dextran (FD-4), across the intestinal mucosa, as well as the nasal mucosa, by an in situ closed-loop method using the rat intestine. PLA was found to enhance the intestinal absorption of FD-4 in a concentration-dependent manner within the concentrations investigated in this study, but segment-specific differences were found to be associated with this effect (ileum>jejunum>duodenumâ§colon). The factors responsible for the segment-specific differences were also investigated by intestinal absorption studies using aprotinin, a trypsin inhibitor, and an analysis of the expression of occludin, a tight junction protein. In the small intestine, the differences in the effect of PLA on the absorption of FD-4 may be related to the enzymatic degradation of PLA. In the colon, the reduced effect of PLA on the absorption of FD-4 may be related to the smaller surface area for absorption and the higher expression of occludin compared with other segments.
Assuntos
Imidazóis/farmacocinética , Absorção Intestinal/efeitos dos fármacos , Peptídeos/farmacologia , Éteres Fenílicos/farmacocinética , Animais , Relação Dose-Resposta a Droga , Masculino , Ratos , Ratos WistarRESUMO
We investigated the effects of α- and ß-adrenoceptor agonists on L-ascorbic acid-induced hepatocyte DNA synthesis and proliferation in primary cultures of adult rat hepatocytes. The results showed that phenylephrine (10(-6) M) and metaproterenol (10(-6) M) alone did not induce hepatocyte DNA synthesis and proliferation. However, when combined with L-ascorbic acid (10(-6) M), these adrenoceptor agonists potentiated the hepatocyte DNA synthesis and proliferation induced by L-ascorbic acid. Then intracellular signal transduction mechanisms for the effects of phenylephrine and metaproterenol on L-ascorbic acid-induced hepatocyte mitogenesis were examined. Western blot analysis showed that phenylephrine and metaproterenol did not potentiate L-ascorbic acid-induced insulin-like growth factor I receptor tyrosine kinase phosphorylation. In contrast, they both significantly potentiated L-ascorbic acid-induced extracellular-signal regulated kinase-2 (ERK2) phosphorylation within 5 min. Moreover, cell-permeable second messenger analogs phorbol ester (10(-7) M) and 8-bromo cAMP (10(-7) M) mimicked the effects of phenylephrine and metaproterenol on L-ascorbic acid-induced ERK2 phosphorylation. The effects of these adrenoceptor agents were specifically antagonized by GF109203X and H-89, respectively. These results indicate that activation of ERK2 via protein kinas C and protein kinase A represents a mechanism for potentiation of L-ascorbic acid-induced hepatocyte DNA synthesis and proliferation in primary cultures of adult rat hepatocytes.
Assuntos
Ácido Ascórbico/farmacologia , DNA/biossíntese , Hepatócitos/citologia , Hepatócitos/efeitos dos fármacos , Receptores Adrenérgicos alfa 1/metabolismo , Receptores Adrenérgicos beta 2/metabolismo , Transdução de Sinais/efeitos dos fármacos , 8-Bromo Monofosfato de Adenosina Cíclica/farmacologia , Agonistas de Receptores Adrenérgicos alfa 1/farmacologia , Agonistas de Receptores Adrenérgicos beta 2/farmacologia , Animais , Proliferação de Células/efeitos dos fármacos , Células Cultivadas , Sinergismo Farmacológico , MAP Quinases Reguladas por Sinal Extracelular/metabolismo , Hepatócitos/metabolismo , Masculino , Metaproterenol/farmacologia , Fenilefrina/farmacologia , Fosforilação/efeitos dos fármacos , Ratos , Ratos Wistar , Receptor IGF Tipo 1/metabolismo , Acetato de Tetradecanoilforbol/farmacologia , Fatores de TempoRESUMO
We investigated the effects of α- and ß-adrenergic agonists on epidermal growth factor (EGF)-stimulated extracellular-signal regulated kinase (ERK) isoforms in primary cultures of adult rat hepatocytes. Hepatocytes were isolated and cultured with EGF (20 ng/ml) and/or α(1)-, α(2)- and ß(2)-adrenergic agonists. Phosphorylated ERK isoforms (ERK1; p44 mitogen-activated protein kinase (MAPK) and ERK2; p42 MAPK) were detected by Western blotting analysis using anti-phospho-ERK1/2 antibody. The results show that EGF induced a 2.5-fold increase in ERK2-, but not ERK1-, phosphorylation within 3 min. This EGF-induced ERK2 activation was abolished by treatment with the EGF-receptor kinase inhibitor AG1478 (10(-7) M) or the MEK (MAPK kinase) inhibitor PD98059 (10(-6) M). The α(2)-adrenergic and ß(2)-adrenergic agonists, UK14304 (10(-6) M) and metaproterenol (10(-6) M), respectively, had no effect in the absence of EGF, but metaproterenol significantly potentiated EGF-induced ERK2 phosphorylation. Moreover, the cell-permeable cAMP analog 8-bromo cAMP (10(-7) M), also potentiated EGF-induced ERK2 phosphorylation. The effects of these analogs were antagonized by the protein kinase A (PKA) inhibitor H-89 (10(-7) M). These results suggest that direct or indirect activation of PKA represents a positive regulatory mechanism for EGF stimulation of ERK2 induction.
Assuntos
AMP Cíclico/agonistas , Fator de Crescimento Epidérmico/metabolismo , Receptores ErbB/metabolismo , MAP Quinases Reguladas por Sinal Extracelular/metabolismo , Hepatócitos/efeitos dos fármacos , Terapia de Alvo Molecular , 8-Bromo Monofosfato de Adenosina Cíclica/farmacologia , Agonistas de Receptores Adrenérgicos alfa 2/farmacologia , Agonistas de Receptores Adrenérgicos beta 2/farmacologia , Animais , Tartarato de Brimonidina , Técnicas de Cultura de Células , Proliferação de Células/efeitos dos fármacos , AMP Cíclico/análogos & derivados , Avaliação Pré-Clínica de Medicamentos , Hepatócitos/fisiologia , MAP Quinase Quinase 2/análise , Masculino , Metaproterenol/farmacologia , Proteína Quinase 3 Ativada por Mitógeno/análise , Fosforilação , Quinoxalinas/farmacologia , Ratos , Ratos Wistar , Transdução de Sinais/efeitos dos fármacosRESUMO
We investigated the effects of the α(1)-adrenergic agonist phenylephrine on platelet-derived growth factor (PDGF)-stimulated extracellular signal-regulated kinase (ERK) in primary cultures of adult rat hepatocytes. Hepatocytes were isolated and cultured with PDGF (10 ng/ml) and/or α-adrenergic agonist. Phosphorylated ERK isoforms (ERK1 and ERK2) were detected by Western blotting analysis using anti-phospho mitogen-activated protein kinase (MAPK) antibody. PDGF stimulated phosphorylation of ERK2 (42 kDa MAPK) by 2.0-fold within 3-5 min. The PDGF-induced ERK activation was abolished by AG1296 (10(-7) M) or LY294002 (10(-7) M) treatment. MAPK kinase inhibitor, PD98059 (10(-6) M), completely inhibited the PDGF-induced increase in ERK activity. In addition, PDGF-induced mammalian target of rapamycin activity was completely inhibited by AG1296, LY294002, PD98059, or rapamycin treatment. Phenylephrine alone showed no effects on ERKs, but significantly increased phosphorylation of ERK2 induced by PDGF. Moreover, a synthetic analog of diacylglycerol (DG), phorbol 12-myristate 13 acetate (TPA; 10(-7) M), potentiated PDGF-induced ERK2 phosphorylation, while ionomycin had no effect (10(-6) M). The effects of phenylephrine and TPA were antagonized by the phospholipase C (PLC) inhibitor U73122 (10(-7) M), and the protein kinase C (PKC) inhibitor GF109203X (10(-7) M), respectively. Accordingly, PDGF-induced DNA synthesis and proliferation in the presence or absence of phenylephrine or TPA were completely inhibited by AG1296, LY294002, PD98059, or rapamycin treatment. These results suggest that activation of PLC/PKC by phenylephrine represent an indirect positive regulatory mechanism for stimulating ERK induced by 10 ng/ml PDGF.
Assuntos
MAP Quinases Reguladas por Sinal Extracelular/metabolismo , Hepatócitos/efeitos dos fármacos , Fenilefrina/farmacologia , Fator de Crescimento Derivado de Plaquetas/farmacologia , 8-Bromo Monofosfato de Adenosina Cíclica/farmacologia , Animais , Western Blotting , Tartarato de Brimonidina , Células Cultivadas , Ativação Enzimática , Hepatócitos/metabolismo , Masculino , Metaproterenol/farmacologia , Fosforilação , Quinoxalinas/farmacologia , Ratos , Ratos Wistar , Transdução de Sinais/efeitos dos fármacos , Serina-Treonina Quinases TOR/metabolismo , Acetato de Tetradecanoilforbol/farmacologiaRESUMO
We investigated the effects of tumor necrosis factor (TNF)-alpha on DNA synthesis and proliferation, and its signal transduction pathways in primary cultures of adult rat hepatocytes. TNF-alpha induced time- and dose-dependent increases in hepatocyte DNA synthesis and proliferation. The hepatocyte proliferation stimulated by 30 ng/ml TNF-alpha was significantly inhibited by anti-TNF receptor 2 antibody, but not by anti-TNF receptor 1 antibody. TNF-alpha-induced hepatocyte DNA synthesis and proliferation were blocked by AG1478 (10(-7) M), PD98059 (10(-6) M), LY 294002 (10(-7) M), and rapamycin (100 ng/ml). TNF-alpha at 30 ng/ml significantly increased phosphorylation of receptor tyrosine kinase (175 kDa) and p42 mitogen-activated protein (MAP) kinase. This data suggests that the proliferative signal for primary cultured hepatocytes induced by TNF-alpha is mediated by TNF receptor 2 and the receptor tyrosine kinase/MAP kinase pathway. In addition, TNF-alpha-induced hepatocyte mitogenesis was significantly blocked by somatostatin (10(-6) M), adenylate cyclase inhibitor dideoxyadenosine (10(-7) M), protein kinase A inhibitor H-89 (10(-7) M), and neutralizing antibody to transforming growth factor (TGF)-alpha in culture. Indeed, 30 ng/ml TNF-alpha was found to rapidly stimulate secretion of TGF-alpha, and this secretion was also blocked by anti-TNF receptor 2 antibody. Moreover, TGF-alpha secretion induced by TNF-alpha was suppressed by dideoxyadenosine, H-89, and somatostatin. Together, these results indicate that stimulation of TNF receptor 2 by 30 ng/ml TNF-alpha induces autocrine secretion of TGF-alpha via the adenylate cyclase/protein kinase A pathway, after which TGF-alpha induces hepatocyte DNA synthesis and proliferation through the TGF-alpha receptor-linked tyrosine kinase (175 kDa)/MAP kinase signaling system.
Assuntos
Proliferação de Células/efeitos dos fármacos , DNA/biossíntese , Hepatócitos/efeitos dos fármacos , Receptores Tipo II do Fator de Necrose Tumoral/fisiologia , Fator de Crescimento Transformador alfa/metabolismo , Fator de Necrose Tumoral alfa/farmacologia , Animais , Anticorpos Monoclonais/farmacologia , Western Blotting , Células Cultivadas , AMP Cíclico/metabolismo , Relação Dose-Resposta a Droga , Ensaio de Imunoadsorção Enzimática , Hepatócitos/enzimologia , Hepatócitos/metabolismo , Masculino , Proteínas Quinases Ativadas por Mitógeno/metabolismo , Fosforilação , Proteínas Tirosina Quinases/metabolismo , Ratos , Ratos Wistar , Receptores Tipo II do Fator de Necrose Tumoral/metabolismo , Transdução de Sinais/efeitos dos fármacos , Fatores de TempoRESUMO
We investigated the effects of alpha(1)- and beta(2)-adrenergic agonists on hepatocyte growth factor (HGF)-stimulated mitogen-activated protein kinase (MAPK) isoforms in primary cultures of adult rat hepatocytes. Hepatocytes were isolated and cultured with HGF (5 ng/ml) and/or alpha- and beta-adrenergic agonists. Phosphorylated MAPK isoforms (p42 and p44 MAPK) were detected by Western blotting analysis using anti-phospho-MAPK antibody. The results show that HGF increased phosphorylation of p42 MAPK by 2.2-fold within 3 min. The HGF-induced MAPK activation was abolished by AG1478 treatment (10(-7) M). The MEK (MAPK kinase) inhibitor PD98059 (10(-6) M) completely inhibited the HGF-dependent increase in MAPK activity. Phenylephrine (10(-6) M) and metaproterenol (10(-6) M) alone had no effect in the absence of HGF, but significantly increased p42 MAPK induction by HGF. Moreover, the cell-permeable cAMP analog, 8-bromo cAMP (10(-7) M), and phorbol 12-myristate 13 acetate (10(-7) M) potentiated HGF-induced MAPK phosphorylation. The effects of these analogs were antagonized by the protein kinase A (PKA) inhibitor H-89 (10(-7) M) and the protein kinase C (PKC) inhibitor sphingosine (10(-6) M), respectively. These results suggest that direct or indirect activation of both PKA and PKC represent a positive regulatory mechanism for stimulating MAPK induction by HGF.
Assuntos
Agonistas Adrenérgicos/farmacologia , Agonistas de Receptores Adrenérgicos alfa 1 , Agonistas de Receptores Adrenérgicos beta 2 , Fator de Crescimento de Hepatócito/farmacologia , Hepatócitos/efeitos dos fármacos , 8-Bromo Monofosfato de Adenosina Cíclica/farmacologia , Androstadienos/farmacologia , Animais , Células Cultivadas , Relação Dose-Resposta a Droga , Ativação Enzimática/efeitos dos fármacos , Inibidores Enzimáticos/farmacologia , Flavonoides/farmacologia , Hepatócitos/citologia , Hepatócitos/metabolismo , Masculino , Proteína Quinase 1 Ativada por Mitógeno/metabolismo , Proteínas Quinases Ativadas por Mitógeno/metabolismo , Modelos Biológicos , Inibidores de Fosfoinositídeo-3 Quinase , Fosforilação/efeitos dos fármacos , Quinazolinas , Ratos , Ratos Wistar , Proteínas Quinases S6 Ribossômicas 70-kDa/antagonistas & inibidores , Sirolimo/farmacologia , Esfingosina/farmacologia , Tirfostinas/farmacologia , WortmaninaRESUMO
Five-hundred thirty one bacterial strains isolated from 412 patients diagnosed as having urinary tract infections (UTIs) in 10 institutions in Japan were supplied between September and December 2001. Then, the clinical background of patients were investigated such as sex, age, and type of infections, infections and kind of bacteria, frequency of bacteria isolation by age and infections, bacteria and infections by timing of antibiotics administration, and bacteria and infections by surgical procedures. With regard to the relationship between age and sex of patients and type of infections, the number of cases aged lower than 50 years was few and complicated UTIs without indwelling catheter was the most frequent in male patients. In females, the number of patients aged lower than 20 years was few. Most of female patients aged lower than 80 years had uncomplicated UTIs. As for the relationship between type of infections and kind of bacteria, Escherichia coli decreased as the infections were more complicated, and Pseudomonas aeruginosa and Enterococcus faecalis increased as the infections were more complicated. In relation of these results to age of patients, isolation frequency of E. coli gradually decreased with aging in patients aged 20 years and older with uncomplicated UTIs. The isolation frequencies of E. faecalis decreased with aging in the patients with complicated UTIs without indwelling catheter while P. aeruginosa decreased with aging in the patients with complicated UTIs with indwelling catheter. E. coli was isolated a few after administration of antibiotics, and P. aeruginosa and E. faecalis were frequently isolated after administration in the patients with all types of infections. As for type of causative organisms in UTIs and with or without surgical operation, E. coli was frequently isolated in the patients without surgery in the patients with uncomplicated UTIs and complicated UTIs without indwelling catheter, while P. aeruginosa was frequently isolated in the patients who underwent surgery in the patients with uncomplicated UTIs and complicated UTIs with indwelling catheter. In uncomplicated UTIs, isolation frequencies of Klebsiella spp., P. aeruginosa, and E. faecalis were significant in the patients with surgery. In complicated UTIs without indwelling catheter, Klebsiella spp. was frequently isolated in the patients with surgery. In complicated UTIs with indwelling catheter, S. aureus and Staphylococcus spp. were frequently isolated in the patients without surgery.
Assuntos
Antibacterianos/farmacologia , Bactérias/efeitos dos fármacos , Bactérias/isolamento & purificação , Infecções Urinárias/microbiologia , Adolescente , Adulto , Fatores Etários , Idoso , Idoso de 80 Anos ou mais , Antibacterianos/uso terapêutico , Criança , Pré-Escolar , Farmacorresistência Bacteriana , Feminino , Humanos , Lactente , Japão/epidemiologia , Masculino , Pessoa de Meia-Idade , Fatores Sexuais , Fatores de Tempo , Infecções Urinárias/tratamento farmacológico , Infecções Urinárias/epidemiologiaRESUMO
PURPOSE: The purpose of the present study is to explore whether a poly-L-arginine (poly-L-Arg)-induced increase in tight junctions (TJ) permeability of fluorescein isothiocyanate-labeled dextran (MW 4.4 kDa, FD-4) is associated with the Ca2+-dependent signaling and occurs following the phosphorylation/dephosphorylation of TJ proteins. METHODS: Excised rabbit nasal epithelium was mounted in an Ussing-type chamber for measurement of FD-4 transport and membrane conductance (Gt) in the presence of various inhibitors that are involved in the Ca2+-dependent pathway and the phosphorylation/dephosphorylation of TJ proteins. The resultant distribution of TJ proteins was observed using confocal laser scanning microscopy (CLSM) in an immunostaining. RESULTS: The increase in TJ permeability of FD4 induced by 0.2 mg/ml poly-L-Arg was not altered by treatment with inhibitors (of possible Ca2+ mobilization pathways followed by exposure of poly-L-Arg, suggesting that the promoting effect of poly-L-Arg is independent of Ca2+-related signaling. On the other hand, the protein kinase C (PKC) and tyrosine phosphatase inhibitors suppress the increase in TJ permeability by poly-L-Arg, indicating that serine/threonine phosphorylation by way of Ca2+-independent PKC and tyrosine dephosphorylation of junction proteins may have occurred. Furthermore, immunofluorescent monitoring of ZO-1, a TJ associated protein, and occludin, an integral membrane protein localizing at TJ, after preincubation with PKC and tyrosine phosphatase inhibitors followed by poly-L-Arg treatment has shown that the internalization of ZO-1 and occludin occurred by way of serine/threonine phosphorylation by PKC activation and by way of tyrosine dephosphorylation, respectively, providing TJ disassembly. CONCLUSIONS: We conclude that poly-L-Arg enhances the paracellular permeability of FD-4 (i.e., macromolecules), at least, by way of both serine/threonine phosphorylation of ZO-1 and tyrosine dephosphorylation of occludin in rabbit nasal epithelium.
Assuntos
Permeabilidade da Membrana Celular , Proteínas de Membrana/metabolismo , Mucosa Nasal/metabolismo , Peptídeos/química , Fosfoproteínas/metabolismo , Serina/metabolismo , Treonina/metabolismo , Tirosina/metabolismo , Animais , Arginina/química , Técnicas In Vitro , Masculino , Mucosa Nasal/citologia , Ocludina , Fosforilação , Coelhos , Proteína da Zônula de Oclusão-1RESUMO
Five-hundred eighty eight bacterial strains isolated from 435 patients diagnosed as having urinary tract infections (UTIs) in 10 institutions in Japan were supplied between August 2000 and July 2001. Then, the clinical background of patients were investigated such as sex, age, and type of infections, infections and kind of bacteria, frequency of bacteria isolation by age and infections, bacteria and infections by timing of antibiotics administration, and bacteria and infections by surgical procedures. About the relationship between age and sex of patients and type of infections, the number of male patients aged less than 50 years was few, and complicated UTIs without indwelling catheter was the most frequent. In females, the number of patients aged less than 20 years was few. The majority of female patients aged 40 years and over had complicated UTIs while uncomplicated UTIs was most frequent in the patients being twenties. As for type of infections and kind of bacteria, Escherichia coli decreased when the infections became complicated, and pseudomonas aeruginosa increased when the infection became complicated. Enterococcus faecalis was isolated more frequently in complicated UTIs than in uncomplicated UTIs. Considering this result by age of patients, isolated frequency of E. coli was gradually decreased with aging in patients aged 20 years and over with uncomplicated UTIs or complicated UTIs without indwelling catheter. The isolated frequencies of Klebsiella spp., P. aeruginosa, and E. faecalis were high in the patients with complicated UTIs without indwelling catheter. In the patients aged 70 years and over with complicated UTIs with indwelling catheter, P. aeruginosa and E. faecalis were frequently isolated. As for type of causative organisms in UTIs before and after the administration of antibiotics, the isolation of bacteria was remarkably decreased after administration in the patients with uncomplicated UTIs and complicated UTIs without indwelling catheter. E. coli decreased after administration of antibiotics, and P. aeruginosa increased after administration in the patients with all types of infections. As for type of causative organisms in UTIs and surgical procedures, E. coli was frequently isolated in the patients without surgery in all types of infections, while P. aeruginosa was frequently isolated in the patients who underwent surgery. In uncomplicated UTIs, Proteus spp. and E. faecalis were frequently isolated in the patients with surgery. In complicated UTIs without indwelling catheter, Klebsiella spp. was frequently isolated in the patients without surgery and E. faecalis was frequently isolated in the patients with surgery. In complicated UTIs with indwelling catheter, most of organisms except P. aeruginosa and S. aureus were frequently isolated in the patients without surgery.
Assuntos
Infecções Urinárias/microbiologia , Adolescente , Adulto , Fatores Etários , Idoso , Bactérias/isolamento & purificação , Cateteres de Demora/efeitos adversos , Criança , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Fatores Sexuais , Procedimentos Cirúrgicos OperatóriosRESUMO
BACKGROUND: Liver dysfunction is a frequent complication that arises in the period following kidney transplantations, often resulting in death. We reported a case proving hemosiderosis as a cause of prolonged liver dysfunction after cadaveric kidney transplantation. METHODS: A 47-year-old man, who had been undergoing hemodialysis, was referred to our hospital on 2 November 1999. On the same day, cadaveric kidney transplantation was performed, and serum creatinine level reached a normal level within 2 weeks after surgery. However, serum transaminase gradually increased in the postoperative period. Serum ALT rose up to 116 IU/L on day 20 after the operation and 215 IU/L on day 30. Microscopic examination by needle biopsy revealed hemosiderosis of the liver. Recombinant human erythropoietin was administered and phlebotomy was performed. Liver function improved as a result. CONCLUSION: Early histological diagnosis can be a useful marker in predicting the course of chronic liver disease.