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2.
Liver Int ; 41(11): 2788-2800, 2021 11.
Artigo em Inglês | MEDLINE | ID: mdl-34328265

RESUMO

BACKGROUND & AIMS: Noncoding RNAs (ncRNAs) play critical roles in hepatocellular carcinoma (HCC) progression. Here, by performing RNA-sequencing (RNA-Seq) profiling, we sought to identify novel ncRNAs that potentially drive the heterogeneous progression of liver cancers. METHODS: RNA-Seq profiles were obtained from 68 HCC specimens and 10 samples of adjacent non-tumour liver tissues. The functional significance of the potential driver ncRNAs was evaluated by cell experiments. RESULTS: TPRG1-AS1 was identified as a potential driver noncoding RNA that promotes heterogeneous liver cancer progression. TPRG1-AS1 induced tumour suppressor RNA-binding motif protein 24 (RBM24), suppressing tumour growth by activating apoptotic tumour cell death. In addition, we report that TPRG1-AS1 acts as a competing endogenous RNA (ceRNA) for RBM24, sponging miR-4691-5p and miR-3659 to interfere with their binding to RBM24. CONCLUSIONS: We suggest that TPRG1-AS1 is a novel ceRNA sponging miR-4691-5p and miR-3659, resulting in RBM24 expression and suppression of liver cancer growth. Our results provide new insights into the functions of ncRNAs in heterogeneous HCC progression.


Assuntos
Carcinoma Hepatocelular , Neoplasias Hepáticas , MicroRNAs , RNA Antissenso/genética , Proteínas de Ligação a RNA , Carcinoma Hepatocelular/genética , Linhagem Celular Tumoral , Proliferação de Células , Progressão da Doença , Regulação Neoplásica da Expressão Gênica , Humanos , Neoplasias Hepáticas/genética , MicroRNAs/genética , Proteínas de Ligação a RNA/genética , Proteínas de Ligação a RNA/metabolismo
3.
BMJ Open ; 11(5): e045051, 2021 05 11.
Artigo em Inglês | MEDLINE | ID: mdl-33980527

RESUMO

INTRODUCTION: The application of advanced technologies in paediatric rehabilitation to improve performance and enhance everyday functioning shows considerable promise. The aims of this systematic review are to investigate the effectiveness of robotic-assisted therapy for upper extremity function in children and adolescents with cerebral palsy and to extend the scope of intervention from empirical evidence. METHODS AND ANALYSIS: Multiple databases, including MEDLINE (Ovid), PubMed, CINAHL, Scopus, Web of Science, Cochrane Library and IEEE Xplore, will be comprehensively searched for relevant randomised controlled trials and non-randomised studies. The grey literature will be accessed on the ProQuest Dissertations & Theses Global database, and a hand search from reference lists of previous articles will be performed. The papers written in English language will be considered, with no limitation on publication date. Two independent reviewers will identify eligible studies, evaluate the level of evidence (the Oxford Centre for Evidence-Based Medicine) and appraise methodological quality and risk of bias (the Standard quality assessment criteria for evaluating primary research papers from a variety of fields (QualSyst tool); the Grading of Recommendations Assessment, Development and Evaluation). Data will be appropriately extracted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guideline. A narrative synthesis will be provided to summarise the results, and a meta-analysis will be conducted if there is sufficient homogeneity across outcomes. PROSPERO REGISTRATION NUMBER: CRD42020205818. ETHICS AND DISSEMINATION: Ethical approval is not required for this study. The findings will be disseminated via a peer-reviewed journal and international conferences.


Assuntos
Paralisia Cerebral , Procedimentos Cirúrgicos Robóticos , Robótica , Adolescente , Criança , Mãos , Humanos , Metanálise como Assunto , Projetos de Pesquisa , Revisões Sistemáticas como Assunto
4.
Int J Med Robot ; 11(3): 296-301, 2015 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-25376750

RESUMO

BACKGROUND: Extralevator abdominoperineal resection (APR) in a prone jackknife position was developed to avoid a positive circumferential resection margin, and its application led to lower rates of local recurrence. The paper describes a technique of robotic extralevator APR with transabdominal levator division followed by pelvic floor reconstruction with bilayered composite mesh. METHODS: A 42-year-old man with low rectal cancer required APR that was performed in a lithotomy position with transabdominal division of the levators. After the perineal phase, the robot was redocked and a bilayered composite mesh was sutured to the pelvic inlet using robotic needle drivers. RESULTS: The specimen had a cylindrical shape, and there was no surgical waist or perforation. Histology revealed a ypT2N0 tumor without circumferential margin involvement. CONCLUSIONS: The robotic interface can aid in APR by accurately transecting the levators from the top. Additionally, it allows suturing of mesh around the pelvic inlet to prevent perineal hernias. Copyright © 2014 John Wiley & Sons, Ltd.

5.
Mol Pharmacol ; 71(3): 835-42, 2007 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-17164407

RESUMO

The primary mechanism for clearance of extracellular dopamine (DA) is uptake mediated by the dopamine transporter (DAT), which is governed, in part, by the number of functional DATs on the cell surface. Previous studies have shown that amphetamine (AMPH) decreases DAT cell surface expression, whereas insulin reverses this effect through the action of phosphatidylinositol 3-kinase (PI3K). Therefore, it is possible that AMPH causes DAT cell surface redistribution by inhibiting basal insulin signaling. Here, we show in a heterologous expression system and in murine striatal synaptosomes that AMPH causes a time-dependent decrease in the activity of Akt, a protein kinase immediately downstream of PI3K. This effect was blocked by the DAT inhibitor cocaine, suggesting that AMPH must interact with DAT to inhibit Akt. We also showed that AMPH is able to stimulate Ca2+/calmodulin-dependent kinase II (CaMKII) activity, both in the heterologous expression system as well as in murine striatal synaptosomes. The ability of AMPH to decrease Akt activity was blocked by the CaMKII inhibitor 2-[N-(2-hydroxyethyl)]-N-(4-methoxybenzenesulfonyl)]amino-N-(4-chlorocinnamyl)-N-methylbenzylamine (KN93), but not by its inactive analog 2-[N-(4-methoxybenzenesulfonyl)]amino-N-(4-chlorocinnamyl)-N-methylbenzylamine (KN92). Furthermore, preincubation with KN93 prevented the AMPH-induced decrease in DAT cell surface expression. Thus, AMPH, but not cocaine, decreases Akt activity through a CaMKII-dependent pathway, thereby providing a novel mechanism by which AMPH regulates insulin signaling and DAT trafficking.


Assuntos
Anfetamina/farmacologia , Proteínas Quinases Dependentes de Cálcio-Calmodulina/fisiologia , Proteínas da Membrana Plasmática de Transporte de Dopamina/fisiologia , Proteínas Proto-Oncogênicas c-akt/antagonistas & inibidores , Benzilaminas/farmacologia , Proteína Quinase Tipo 2 Dependente de Cálcio-Calmodulina , Proteínas Quinases Dependentes de Cálcio-Calmodulina/antagonistas & inibidores , Células Cultivadas , Cocaína/farmacologia , Corpo Estriado/efeitos dos fármacos , Corpo Estriado/metabolismo , Proteínas da Membrana Plasmática de Transporte de Dopamina/análise , Humanos , Fosfatidilinositol 3-Quinases/fisiologia , Sulfonamidas/farmacologia , Sinaptossomos/metabolismo
6.
Korean Journal of Medicine ; : 432-436, 2004.
Artigo em Coreano | WPRIM (Pacífico Ocidental) | ID: wpr-99259

RESUMO

Carcinoma of the pancreas represents less than 5% of human malignant neoplasm. It's skin involvement is rare. A 73-year-old man presented with multiple skin lesions located on the face, neck and body. The histopathologic study of the skin lesion was confirmed to be an metastatic adenocarcinoma. The primary tumor was regarded as the mass at the head of the pancreas observed on the CT scan, but was not confirmed by biopsy. We report a case of multiple cutaneous metastasis from pancreatic carcinoma with brief review of related literature.


Assuntos
Idoso , Humanos , Adenocarcinoma , Biópsia , Cabeça , Pescoço , Metástase Neoplásica , Pâncreas , Pele , Tomografia Computadorizada por Raios X
7.
Eur J Clin Pharmacol ; 58(6): 423-9, 2002 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-12242602

RESUMO

OBJECTIVE: The objectives of this study were to assess the effect of mirtazapine on steady-state pharmacokinetics of phenytoin and vice versa and to assess tolerability and safety of the combined use of mirtazapine and phenytoin. METHODS: This was an open-label, randomised, parallel-groups, single-centre, multiple-dose pharmacokinetic study. Seventeen healthy, male subjects completed either treatment A [nine subjects: daily 200 mg phenytoin for 17 days plus mirtazapine (15 mg for 2 days continuing with 30 mg for 5 days) from day 11 to day 17] or treatment B [eight subjects: mirtazapine, daily 15 mg for 2 days continuing with 30 mg for 15 days plus phenytoin 200 mg from day 8 to day 17]. Serial blood samples were taken for kinetic profiling on the 10th and 17th days of treatment A and on the 7th and 17th days of treatment B. Induction of CYP 3A by phenytoin was evaluated by measuring the ratio of 6 beta-hydroxycortisol over cortisol on the 1st, 7th and 17th days of treatment B. RESULTS: Co-administration of mirtazapine had no effect on the steady-state pharmacokinetics of phenytoin, i.e. the area under the plasma concentration-time curve (AUC)(0-24) and peak plasma concentration (C(max)) remained unchanged. The addition of phenytoin to an existing daily administration of mirtazapine resulted in a mean (+/-SD) decrease of the AUC(0-24) from 576+/-104 ng h/ml to 305+/-81.6 ng h/ml and a mean decrease of C(max) from 69.7+/-17.5 ng/ml to 46.9+/-10.9 ng/ml. Induction of CYP 3A by phenytoin is confirmed by the significantly ( P=0.001) increased 6beta-hydroxycortisol/cortisol ratio from 1.74+/-1.00 to 2.74+/-1.64. CONCLUSION: Co-administration of mirtazapine did not alter the steady-state pharmacokinetics of phenytoin. The addition of phenytoin to an existing daily administration of mirtazapine results in a decrease of the plasma concentrations of mirtazapine by 46% on average, most likely due to induction of CYP 3A3/4.


Assuntos
Anticonvulsivantes/farmacocinética , Antidepressivos Tricíclicos/farmacocinética , Mianserina/farmacocinética , Fenitoína/farmacocinética , Administração Oral , Adolescente , Adulto , Anticonvulsivantes/administração & dosagem , Anticonvulsivantes/efeitos adversos , Antidepressivos Tricíclicos/administração & dosagem , Antidepressivos Tricíclicos/efeitos adversos , Área Sob a Curva , Interações Medicamentosas , Humanos , Masculino , Mianserina/administração & dosagem , Mianserina/efeitos adversos , Mianserina/análogos & derivados , Pessoa de Meia-Idade , Mirtazapina , Fenitoína/administração & dosagem , Fenitoína/efeitos adversos
8.
J Pharmacol Exp Ther ; 299(2): 666-77, 2001 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-11602680

RESUMO

Presynaptic, cocaine- and antidepressant-sensitive norepinephrine (NE) transporters (NETs) dictate levels of extracellular NE after vesicular release. Recent studies suggest that G protein-coupled receptors linked to protein kinase C (PKC) down-regulate cell surface NET protein levels and diminish NE uptake capacity. We identified distinct phosphatidylinositol 3-OH kinase (PI3K)-linked pathways supporting basal and insulin-triggered NE transport in the human noradrenergic neuroblastoma, SK-N-SH. Acute (0-60 min) insulin treatments produced a time- and concentration-dependent stimulation of NE transport, resolved in kinetic studies as an enhancement of NE transport capacity (Vmax) without an alteration in NE Km. Basal and insulin-modulated NET activities were reduced by the tyrosine kinase inhibitor genistein and the PI3K inhibitors wortmannin and LY-294002, but not by the PKC inhibitor staurosporine. PI3K activation was found to support phosphorylation of p38 mitogen-activated protein kinase (p38 MAPK). However, basal and insulin-stimulated NET activities were differentiated by their reliance on p38 MAPK activation. Thus, the p38 MAPK inhibitor SB203580 and SB202190 abolished insulin activation of NE transport yet failed to impact basal NET activity. Moreover, p38 MAPK activation and insulin activation of NETs were found to be sensitive to external Ca2+ depletion, blockade of voltage-sensitive Ca2+ channels, and inhibition of protein phosphatase 2A. Effects of tyrosine kinase and PI3K inhibitors on basal NET uptake appear to arise from a loss of cell surface NET protein, whereas the p38 MAPK-dependent enhancement of NE transport occurs without a detectable enhancement of surface NET. Our findings establish two distinct pathways for regulation of NE uptake involving PI3K, one linked to transporter trafficking and a second linked to Ca2+-dependent, p38 MAPK phosphorylation that promotes activation of cell surface NETs.


Assuntos
Fluoxetina/análogos & derivados , Hipoglicemiantes/farmacologia , Insulina/farmacologia , Proteínas Quinases Ativadas por Mitógeno/metabolismo , Norepinefrina/metabolismo , Simportadores/metabolismo , Western Blotting , Cálcio/metabolismo , Linhagem Celular , Fluoxetina/metabolismo , Humanos , Indicadores e Reagentes , Proteínas da Membrana Plasmática de Transporte de Norepinefrina , Fosfatidilinositol 3-Quinases/metabolismo , Proteínas Tirosina Quinases/metabolismo , Ensaio Radioligante , Receptores Muscarínicos/efeitos dos fármacos , Receptores Muscarínicos/metabolismo , Transdução de Sinais/efeitos dos fármacos , Proteínas Quinases p38 Ativadas por Mitógeno
10.
Am J Pathol ; 153(6): 1937-45, 1998 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-9846983

RESUMO

Programmed cell death (PCD) is a prominent feature of the development of the immune and nervous systems. In both systems, widespread PCD occurs in primitive progenitor cells during development. In this study, we demonstrated that Ewing's sarcoma (ES) cells, undifferentiated neural precursors, underwent apoptosis upon engagement of CD99 with anti-CD99 monoclonal antibody. Apoptosis via CD99 occurred only in the undifferentiated state of ES cells, but not in differentiated ES cells. CD99-induced apoptosis in ES cells appeared to require de novo synthesis of RNA and protein as well as caspase activation. Cyclosporin A, known to be a potent inhibitor of both calcineurin activation and mitochondrial permeability transition pore opening, inhibited CD99-mediated apoptosis, whereas FK-506, a specific calcineurin inhibitor, did not, indicating the induction of CD99-mediated apoptosis through a calcineurin-independent pathway. Furthermore, the dying cells displayed the reduction of mitochondrial transmembrane potential (delta psi m). These results suggest that CD99 engagement induce CsA-inhibitable mitochondrial permeability transition pore opening, followed by a reduction of delta psi m and caspase activation, thereby leading to apoptosis. Based on these results, we suggest the possible involvement of CD99 in the apoptotic processes that occur during nervous system development and also its application in immunotherapeutic trials for ES cases.


Assuntos
Antígenos CD/fisiologia , Apoptose , Moléculas de Adesão Celular/fisiologia , Sarcoma de Ewing/patologia , Antígeno 12E7 , Anticorpos Monoclonais/farmacologia , Antígenos CD/imunologia , Calcineurina , Cálcio/fisiologia , Inibidores de Caspase , Caspases/fisiologia , Moléculas de Adesão Celular/imunologia , Diferenciação Celular , Ciclosporina/farmacologia , Dactinomicina/farmacologia , Técnica Indireta de Fluorescência para Anticorpo , Humanos , Potenciais da Membrana , Microscopia Confocal , Microscopia Eletrônica , Neuroblastoma/patologia , Tumores Neuroectodérmicos Primitivos/patologia , Tacrolimo/farmacologia , Células Tumorais Cultivadas
11.
Mol Cells ; 8(2): 169-74, 1998 Apr 30.
Artigo em Inglês | MEDLINE | ID: mdl-9638648

RESUMO

We have previously reported CD4 expression in CD34+ hematopoietic progenitor cells and suggested a role of CD4 in normal hematopoiesis and its possible relationship with the pathogenesis of acquired immunodeficiency syndrome (AIDS). To investigate whether CD4 expression in bone marrow progenitor cells can explain bone marrow suppression in AIDS, monoclonal antibodies (mAbs) against human CD4 were developed by immunizing Balb/c mice with human thymocytes. Three mAbs completely blocked the binding of Leu3a antibody, a well-known anti-CD4 mAb, to thymocytes, which indicates overlap between the epitopes recognized by these and Leu3a antibodies. Interestingly, one of these mAbs, YG23, significantly inhibited colony formation of human bone marrow progenitor cells treated with GM-CSF. This is the first demonstration that ligation of CD4 by an anti-CD4 mAb suppresses GM-CSF mediated proliferation and differentiation of human hematopoietic progenitor cells by modifying the intracellular signaling pathway through CD4 molecules. Based on these findings, we propose that alteration of CD4 signaling by either cross-linked gp120 or antibodies directed against a certain epitope shared with the YG23 binding site of the CD4 molecule may play a role in bone marrow dysfunction in AIDS patients.


Assuntos
Anticorpos Monoclonais/farmacologia , Antígenos CD4/imunologia , Células-Tronco Hematopoéticas/citologia , Células-Tronco Hematopoéticas/efeitos dos fármacos , Animais , Anticorpos Monoclonais/biossíntese , Anticorpos Monoclonais/imunologia , Sítios de Ligação de Anticorpos/efeitos dos fármacos , Sítios de Ligação de Anticorpos/imunologia , Divisão Celular/efeitos dos fármacos , Divisão Celular/imunologia , Ensaio de Unidades Formadoras de Colônias , Feminino , Fator Estimulador de Colônias de Granulócitos e Macrófagos/antagonistas & inibidores , Fator Estimulador de Colônias de Granulócitos e Macrófagos/imunologia , Fator Estimulador de Colônias de Granulócitos e Macrófagos/farmacologia , Células-Tronco Hematopoéticas/imunologia , Humanos , Leucócitos Mononucleares/citologia , Leucócitos Mononucleares/efeitos dos fármacos , Leucócitos Mononucleares/imunologia , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Ligação Proteica/efeitos dos fármacos , Ligação Proteica/imunologia , Timo/citologia , Timo/imunologia
12.
Mol Cells ; 7(2): 272-7, 1997 Apr 30.
Artigo em Inglês | MEDLINE | ID: mdl-9163744

RESUMO

Laminin, a multidomain glycoprotein in basement membranes, interacts with heparin through the terminal globular domain (G domain) of its long arm. The interaction with heparin is thought to be important for modulation of basement membrane assembly and adhesion to cells. The G domain contains two different heparin binding activities: a strong one in the proximal portion and a moderate one in the distal portion of globule. The proximal activity was found to be weak in fragment E8 and in the intact laminin long arm, whose three-chain moieties are joined together in a triple-helical coiled-coil. Dissociation of the A chain of E8 from its B chain moieties by denaturation and chain separation resulted in the exposure of heparin binding activity the in the globular domain. Furthermore, when a recombinant G domain with a distal alpha-helical domain was intercalated into the B chains of E8, the triple alpha-helix was reconstituted and heparin binding was considerably reduced. This data provides evidence for the influence of non-heparin binding rod domain on the binding activity in the G domain.


Assuntos
Heparina/metabolismo , Laminina/química , Laminina/metabolismo , Animais , Sítios de Ligação , Técnicas In Vitro , Camundongos , Fragmentos de Peptídeos/química , Fragmentos de Peptídeos/metabolismo , Ligação Proteica , Desnaturação Proteica , Estrutura Secundária de Proteína , Estrutura Terciária de Proteína
13.
Eur J Biochem ; 250(1): 138-43, 1997 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-9432001

RESUMO

Basement membrane laminin (laminin-1) is a multidomain glycoprotein that interacts with itself, heparin and cells. The interaction with heparin/heparan sulfate proteglycans is thought to be important for the architectural formation of basement membranes and adhesion to cells. The major heparin binding site has been known to reside in the long arm globular domain (G domain). The G domain is in turn subdivided into five subdomains (G1-G5). In order to localize the heparin binding regions further, recombinant G domains (rG and rG5) were expressed in Sf9 insect cells using baculovirus expression vector. By the limited proteolysis of recombinant G domains followed by either heparin affinity HPLC or overlay with radiolabeled heparin, the relative affinity of each subdomain to heparin was assigned as G1>G2 = G4>G5>G3, such that G1 bound strongly and G3 not at all. Since the activity in G1-G3 is cryptic in intact laminin long arm [Sung, U., O'Rear, J. J. & Yurchenco, P. D. (1993) J. Cell Biol. 123, 1255-1268], the active heparin binding site of G domain appears to be located in G4 and proximal G5.


Assuntos
Heparina/metabolismo , Laminina/química , Sequência de Aminoácidos , Animais , Baculoviridae/genética , Sítios de Ligação , Western Blotting , Linhagem Celular , Cromatografia de Afinidade , Quimotripsina/metabolismo , Eletroforese em Gel de Poliacrilamida , Laminina/genética , Laminina/metabolismo , Dados de Sequência Molecular , Fragmentos de Peptídeos/genética , Fragmentos de Peptídeos/isolamento & purificação , Fragmentos de Peptídeos/metabolismo , Ligação Proteica , Proteínas Recombinantes/química , Proteínas Recombinantes/metabolismo , Análise de Sequência , Spodoptera , Tripsina/metabolismo
14.
Heart ; 75(2): 159-64, 1996 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-8673754

RESUMO

OBJECTIVE: To evaluate the efficacy and safety of the second generation dihydropyridine calcium channel blocker lacidipine in patients with heart failure. DESIGN: Placebo controlled, parallel group, double blind study over 8 weeks. SETTING: General community hospital in Breda, The Netherlands. PATIENTS: A random sample was studied of 25 outpatients with symptoms of mild to moderate heart failure, despite treatment with diuretics, digoxin, and angiotensin converting enzyme inhibitors. Their mean age was 65 years, with mean left ventricular ejection fraction of 0.24 and a peak oxygen consumption of 14.4 ml/min/kg. Two patients dropped out on lacidipine, one patient on placebo. INTERVENTION: Treatment with lacidipine 4 mg once daily or placebo for eight weeks. MAIN OUTCOME MEASURE: Cardiopulmonary exercise testing, invasive haemodynamics, and plasma neurohormones. RESULTS: Treatment with lacidipine 4 mg once daily, as compared to placebo treatment, significantly improved peak oxygen consumption (P < 0.02), cardiac index (P < 0.01), and stroke volume (P < 0.03) paralleled by a decrease in systemic vascular resistance (P < 0.03) and arteriovenous oxygen content difference (P < 0.01). Plasma noradrenaline, plasma renin activity, and aldosterone values did not differ between lacidipine and placebo. CONCLUSIONS: This second generation dihydropyridine may be of value as an adjunct to standard treatment in congestive heart failure patients.


Assuntos
Bloqueadores dos Canais de Cálcio/uso terapêutico , Di-Hidropiridinas/uso terapêutico , Insuficiência Cardíaca/tratamento farmacológico , Hemodinâmica/efeitos dos fármacos , Consumo de Oxigênio/efeitos dos fármacos , Idoso , Aldosterona/sangue , Inibidores da Enzima Conversora de Angiotensina/uso terapêutico , Digoxina/uso terapêutico , Diuréticos/uso terapêutico , Método Duplo-Cego , Quimioterapia Combinada , Feminino , Insuficiência Cardíaca/sangue , Insuficiência Cardíaca/fisiopatologia , Humanos , Masculino , Pessoa de Meia-Idade , Norepinefrina/sangue , Estudos Prospectivos , Renina/sangue , Volume Sistólico/efeitos dos fármacos , Resistência Vascular/efeitos dos fármacos
15.
J Cell Biol ; 123(5): 1255-68, 1993 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-8267779

RESUMO

The long arm of laminin, which binds heparin and cells, consists of three polypeptides (A, B1, and B2) joined in a coiled-coil rod attached to a terminal A chain globule (G). Previously, we found that recombinant globular domain (rG) supported heparin and myoblast binding (Yurchenco, P. D., U. Sung, M. D. Ward, Y. Yamada, and J. J. O'Rear. 1993. J. Biol. Chem. 268:8356-8365). To further analyze long arm functions, we expressed the distal moiety of the mouse laminin A chain extending from the middle of the rod to the carboxyl terminus (rAiG). This larger glycoprotein, secreted by Sf9 insect cells infected with recombinant baculovirus, was intercalated in vitro into the corresponding disulfide-linked B chain segments of laminin fragment E8 (distal long arm rod and proximal globule). The hybrid molecule (B-rAiG) possessed a structure similar to laminin long arm as judged by electron microscopy and limited proteolysis. By joining rAiG with E8-B chains, the affinity of G domain for heparin decreased from that observed with rAiG and rG to one similar to native protein. HT1080 cells adhered to E8, rAiG, and B-rAiG, less well to rG, and not to denatured E8/B-rAiG, the A and B chain moieties of E8, or to a mixture of rG and E8-B chains. Cell adhesion to E8 and B-rAiG, in contrast to rAiG, was inhibited with antibodies specific for alpha 6 and beta 1 integrin chains. Since intercalation (a) restored a conformationally dependent alpha 6 beta 1 integrin recognition site present in native protein, (b) inactivated a cryptic cell binding activity in the A chain, and (c) inhibited a heparin binding site present in proximal G domain, we conclude that biological activities of laminin are different from that of its isolated subunits.


Assuntos
Adesão Celular/fisiologia , Heparina/metabolismo , Laminina/metabolismo , Animais , Humanos , Laminina/efeitos dos fármacos , Laminina/genética , Laminina/ultraestrutura , Camundongos , Modelos Moleculares , Elastase Pancreática/metabolismo , Ligação Proteica , Proteínas Recombinantes de Fusão/metabolismo , Proteínas Recombinantes/metabolismo , Células Tumorais Cultivadas
16.
J Biol Chem ; 268(11): 8356-65, 1993 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-8463343

RESUMO

A recombinant mouse cDNA fragment encoding the G domain of the basement membrane laminin A chain was inserted into the eukaryotic baculovirus expression vector pVL1392 modified to produce fusion proteins carrying the rat fibronectin signal. G domain, expressed and secreted as a soluble glycoprotein (rG), was purified to near homogeneity without denaturing conditions. By electron microscopy rG possessed the same globular morphology as found in laminin. rG was cleaved with elastase into two fragments, rG70 and rG50. The latter fragment possessed the identical N terminus as laminin fragment E3 and both shared the same secondary structure by circular dichroism. rG, and rG containing a deletion (residues 2980-3028) rich in basic residues bound to heparin with similar avidity. rG also promoted mouse C2 myoblast cell adhesion and spreading, and evaluation of myoblasts on rG70 and rG50 further revealed that cell spreading was an activity confined to the more proximal sequence of rG70. Antibody specific for rG70 completely blocked cell adhesion to intact laminin in contrast to antibody specific for E3. Finally rG did not inhibit laminin polymerization. These data support the role of G domain in cell and heparin binding, but not laminin self-assembly, and the approach provides a means to further characterize these functions.


Assuntos
Adesão Celular/efeitos dos fármacos , Heparina/metabolismo , Laminina/farmacologia , Músculos/fisiologia , Fragmentos de Peptídeos/farmacologia , Animais , Anticorpos , Especificidade de Anticorpos , Baculoviridae/genética , Linhagem Celular , Dicroísmo Circular , Fibronectinas/genética , Vetores Genéticos , Laminina/química , Laminina/ultraestrutura , Camundongos , Microscopia Eletrônica , Mariposas , Músculos/citologia , Músculos/efeitos dos fármacos , Elastase Pancreática , Fragmentos de Peptídeos/isolamento & purificação , Ligação Proteica , Ratos , Proteínas Recombinantes/química , Proteínas Recombinantes/farmacologia , Proteínas Recombinantes/ultraestrutura , Deleção de Sequência , Transfecção
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