Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 58
Filtrar
1.
Horm Metab Res ; 54(8): 494-495, 2022 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-35944523

RESUMO

The COVID-19 Pandemic has led to a world health crisis with major socioeconomic consequences that have deeply affected our daily lives. Until the end of May 2022, more than 500 million people have been infected by COVID-19 and more than 6 million have died from the disease. Unprecedented efforts in research, illustrated by the more than 250 000 publications in PubMed, have led to the identification of important pathophysiological mechanisms affected by SARS-CoV-2 and have resulted in the development of effective vaccines and treatment protocols for patients with COVID-19.


Assuntos
COVID-19 , Humanos , Pandemias/prevenção & controle , SARS-CoV-2
2.
Horm Metab Res ; 54(9): 583-586, 2022 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-35793708

RESUMO

Diabetes mellitus is one of the most frequent diseases in the general population. Electrical stimulation is a treatment modality based on the transmission of electrical pulses into the body that has been widely used for improving wound healing and for managing acute and chronic pain. Here, we discuss recent advancements in electroceuticals and haptic/smart devices for quality of life and present in which patients and how electrical stimulation may prove to be useful for the treatment of diabetes-related complications.


Assuntos
Complicações do Diabetes , Diabetes Mellitus , Diabetes Mellitus/terapia , Estimulação Elétrica , Humanos , Qualidade de Vida , Têxteis
3.
Internist (Berl) ; 63(1): 4-11, 2022 Jan.
Artigo em Alemão | MEDLINE | ID: mdl-34928398

RESUMO

Diseases of the adrenal cortex require particular attention during the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic. Firstly, SARS-CoV­2 infections can give rise to extrapulmonary manifestations and cause endocrine disorders, particularly in the adrenal cortex. Furthermore, patients with pre-existing insufficiency of the adrenal cortex or hypercortisonism are particularly at risk from a severe infection such as SARS-CoV­2, to suffer from additional complications or a more severe course of a SARS-CoV­2 infection with a higher mortality. Especially in hemodynamically unstable patients with a SARS-CoV­2 infection, diseases of the adrenal glands should also be considered in the differential diagnostics and if necessary clarified, if this is not already known. Prolonged treatment of patients with a SARS-CoV­2 infection with regimens containing high doses of glucocorticoids can also result in a secondary adrenal insufficiency. In order to address these special aspects, some practical recommendations for the diagnostic and therapeutic management of functional disorders of the adrenal glands in patients with a SARS-CoV­2 infection are therefore presented.


Assuntos
Córtex Suprarrenal , Insuficiência Adrenal , COVID-19 , Insuficiência Adrenal/diagnóstico , Insuficiência Adrenal/tratamento farmacológico , Humanos , Pandemias , SARS-CoV-2
4.
Psychopathology ; 48(1): 11-7, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25227592

RESUMO

BACKGROUND: Self-generated coping strategies and the enhancement of coping strategies are effective in the treatment of psychotic symptoms. Evaluating these strategies can be of clinical interest to develop better coping enhancement therapies. Cognitive models consider delusions as multidimensional phenomena. Using a psychometric approach, the relationship between coping and the dimensions of delusion were examined. METHODS: Thirty schizophrenia spectrum patients with delusions and 29 patients with affective disorder with psychotic symptoms were interviewed using the Heidelberg Coping Scales for Delusions and the Heidelberg Profile of Delusional Experience. Analyses of variance were conducted to investigate differences between the groups, and Spearman's rank-based correlations were used to examine the correlations between coping factors and the dimensions of delusion. RESULTS: Schizophrenia spectrum patients used more medical care and symptomatic coping, whereas patients with affective disorder engaged in more depressive coping. In the schizophrenia spectrum sample, the action-oriented, the cognitive, and the emotional dimensions of delusion were related to coping factors. In patients with affective disorder, only the action-oriented dimension was related to coping factors. CONCLUSION: Patients with schizophrenia and affective disorder cope differently with delusions. The dimensions of delusion are related to coping and should be regarded when using cognitive therapy approaches to enhance coping strategies.


Assuntos
Adaptação Psicológica , Transtornos Psicóticos Afetivos/psicologia , Delusões/psicologia , Psicologia do Esquizofrênico , Adulto , Idoso , Família , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Testes Neuropsicológicos , Psicometria , Fatores Socioeconômicos , Adulto Jovem
5.
Cardiovasc Diabetol ; 12: 45, 2013 Mar 13.
Artigo em Inglês | MEDLINE | ID: mdl-23497152

RESUMO

OBJECTIVE: We tested the effects of structured health care for the diabetic foot in one region in Germany aiming to reduce the number of major amputations. RESEARCH DESIGN AND METHODS: In a prospective study we investigated patients with diabetic foot in a structured system of outpatient, in-patient and rehabilitative treatment. Subjects were recruited between January 1st, 2000 and December 31, 2007. All participants underwent a two-year follow-up. The modified University of Texas Wound Classification System (UT) was the basis for documentation and data analysis. We evaluated numbers of major amputations, rates of ulcer healing and mortality. In order to compare the effect of the structured health care program with usual care in patients with diabetic foot we evaluated the same parameters at another regional hospital without interdisciplinary care of diabetic foot (controls). RESULTS: 684 patients with diabetic foot and 508 controls were investigated. At discharge from hospital 28.3% (structured health care program, SHC) vs. 23.0% (controls) of all ulcers had healed completely. 51.5% (SHC) vs. 49.8% (controls) were in UT grade 1.Major amputations were performed in 32 subjects of the structured health care program group (4.7%) vs. 110 (21.7%) in controls (p<0.0001). Mortality during hospitalization was 2.5% (SHC) vs. 9.4% in controls (p<0.001). CONCLUSIONS: With the structured health care program we achieved a significant reduction of major amputation rates by more than 75% as compared to standard care.


Assuntos
Amputação Cirúrgica/tendências , Atenção à Saúde/tendências , Pé Diabético/epidemiologia , Pé Diabético/cirurgia , Idoso , Idoso de 80 Anos ou mais , Pé Diabético/diagnóstico , Feminino , Seguimentos , Alemanha/epidemiologia , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos
6.
Psychopathology ; 45(4): 244-51, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-22653293

RESUMO

BACKGROUND: Coping is of substantial relevance in the treatment and course of psychiatric disorders. Standardized instruments to assess coping with psychotic symptoms, particularly delusions, are rare. The aim of this study was to develop and evaluate the psychometric properties of a new instrument to assess coping strategies in the context of delusional experiences: the Heidelberg Coping Scales for Delusions (HCSD). METHODS: Two hundred and twelve inpatients with schizophrenia spectrum disorders and affective disorders currently experiencing delusions were interviewed with the HCSD and other coping assessment instruments. Psychometric properties and factor structure were analyzed. RESULTS: The HCSD showed good inter-rater reliability and convergent validity. Factor analysis yielded an interpretable structure with five factors: resource-oriented coping, medical care, distraction, cognitive coping, and depressive coping. Symptomatic behavior, due to its particular characteristics, was considered apart. CONCLUSION: The HCSD is a reliable and valid instrument for the assessment of coping strategies in patients with delusions. Further research is needed to evaluate coping changes over time and their influence on treatment and clinical outcomes.


Assuntos
Adaptação Psicológica , Delusões/psicologia , Transtornos do Humor/psicologia , Psicometria , Transtornos Psicóticos/psicologia , Psicologia do Esquizofrênico , Adolescente , Adulto , Idoso , Análise Fatorial , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Reprodutibilidade dos Testes
7.
Lancet Diabetes Endocrinol ; 10(3): 221-230, 2022 03.
Artigo em Inglês | MEDLINE | ID: mdl-35114136

RESUMO

Current evidence suggests that severity and mortality of COVID-19 is higher in men than in women, whereas women might be at increased risk of COVID-19 reinfection and development of long COVID. Differences between sexes have been observed in other infectious diseases and in the response to vaccines. Sex-specific expression patterns of proteins mediating virus binding and entry, and divergent reactions of the immune and endocrine system, in particular the hypothalamic-pituitary-adrenal axis, in response to acute stress might explain the higher severity of COVID-19 in men. In this Personal View, we discuss how sex hormones, comorbidities, and the sex chromosome complement influence these mechanisms in the context of COVID-19. Due to its role in the severity and progression of SARS-CoV-2 infections, we argue that sexual dimorphism has potential implications for disease treatment, public health measures, and follow-up of patients predisposed to the development of long COVID. We suggest that sex differences could be considered in future pandemic surveillance and treatment of patients with COVID-19 to help to achieve better disease stratification and improved outcomes.


Assuntos
COVID-19 , Disparidades nos Níveis de Saúde , Caracteres Sexuais , COVID-19/complicações , COVID-19/epidemiologia , COVID-19/fisiopatologia , Feminino , Humanos , Sistema Hipotálamo-Hipofisário , Masculino , Sistema Hipófise-Suprarrenal , Saúde Pública , Síndrome de COVID-19 Pós-Aguda
8.
Psychopathology ; 43(6): 373-80, 2010.
Artigo em Inglês | MEDLINE | ID: mdl-20847584

RESUMO

BACKGROUND: Research suggests delusions may be better viewed as multidimensional rather than dichotomous phenomena. The aim of this study was to assess the reliability and validity of a German version of the Characteristics of Delusions Rating Scale (CDRS) as an expert rating scale. METHOD: 200 inpatients with schizophrenic spectrum and affective disorders with delusions were assessed with the CDRS and other delusion rating scales. Factorial validity was analysed, and differences between diagnostic groups on the CDRS subscales as well as on the total score were examined. RESULTS: The CDRS was found to have good inter-rater reliability and internal consistency as an expert rating. Factor analysis yielded an interpretable structure with 3 factors - cognition, emotion and bizarreness - accounting for 70% of the variance. The convergent and differential validity of the scales was supported. Compared to other scales, the CDRS measures all dimensions of delusional experience that have been suggested to date with the exception of behavioural aspects. CONCLUSIONS: The results support the view of delusions as multidimensional phenomena. The CDRS as an expert rating is a reliable and valid assessment tool for dimensions of delusional experience and an economical instrument for research and clinical practice. Further research is needed to examine the dimensional structure underlying delusional phenomena and the relationship of the dimensions to neurobiological and psychotherapeutic processes.


Assuntos
Delusões/diagnóstico , Transtornos Mentais/psicologia , Escalas de Graduação Psiquiátrica , Adolescente , Adulto , Idoso , Delusões/complicações , Delusões/psicologia , Análise Fatorial , Feminino , Humanos , Masculino , Transtornos Mentais/complicações , Pessoa de Meia-Idade , Psicometria , Reprodutibilidade dos Testes
9.
Psychopathology ; 43(3): 189-96, 2010.
Artigo em Inglês | MEDLINE | ID: mdl-20375541

RESUMO

BACKGROUND: Delusional experience is a fundamental symptom of psychotic illness. Over recent years, a multidimensional perspective has become increasingly important regarding this phenomenon. Several instruments to measure different dimensions of delusions have been constructed. The aims of this study were to examine the reliability and validity of a German version of the Dimensions of Delusional Experience Scale (DDE). METHODS: Two hundred inpatients with a schizophrenic spectrum disorder or an affective disorder with delusions were examined with the DDE, the Positive and Negative Syndrome Scale (PANSS) and other rating scales for delusional experiences. RESULTS: The scale was found to have good reliability and excellent inter-rater reliability. The 2 factors, delusional involvement and delusional construct, found by Kendler et al. [Am J Psychiatry 1983;140:466-469] could be replicated. The convergent and differential validity of the scale was supported. Besides the content-related aspect 'bizarreness', the DDE mainly assesses cognitive aspects, emotional and behavioral aspects are not incorporated. CONCLUSIONS: The results support the value of a multidimensional perspective of delusional experiences. The German version of the DDE is a reliable and valid assessment tool for different dimensions of delusions, and an economical instrument for research and clinical practice. Further research is needed to reveal the dimensional structure underlying delusional experience.


Assuntos
Delusões/diagnóstico , Delusões/psicologia , Transtornos Psicóticos/psicologia , Psicologia do Esquizofrênico , Delusões/complicações , Análise Fatorial , Humanos , Seleção de Pacientes , Inventário de Personalidade , Escalas de Graduação Psiquiátrica , Psicometria , Transtornos Psicóticos/complicações , Transtornos Psicóticos/diagnóstico , Reprodutibilidade dos Testes , Esquizofrenia/complicações , Esquizofrenia/diagnóstico , Índice de Gravidade de Doença , Inquéritos e Questionários
10.
Clin J Sport Med ; 20(2): 117-9, 2010 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-20215894

RESUMO

OBJECTIVE: The aim of this study was to explore effectors of the pituitary-testicular axis suitable as potential biochemical markers to screen for testosterone doping. DESIGN: Pilot study with male bodybuilding athletes with a self-reported history of testosterone doping (repeated intramuscular administration of testosterone preparations, last injection 8 weeks or less ago) compared with an equal sized control group matched for sex, age, and body mass index. SETTING: Endocrine outpatients. PARTICIPANTS: Fifteen healthy young men of white background. INTERVENTIONS: None. MAIN OUTCOME MEASURES: Inhibin B, testosterone, luteinizing hormone (LH), follicle-stimulating hormone (FSH). RESULTS: Although the levels of testosterone, LH, and FSH did not differ between the 2 groups, the serum concentrations of inhibin B in individuals with a history of testosterone doping were exclusively at or below the lower limit of the normal range for adult men (100-400 pg/mL). Inhibin B was significantly lower in those men who used testosterone for weight lifting (76.1 +/- 36.3 ng/L [mean +/- SD]) than in controls (182.1 +/- 35.4 ng/L). CONCLUSION: A low concentration of serum inhibin B may reflect the application of exogenous testosterone and appears to be a potential marker associated with anabolic androgenic steroid doping.


Assuntos
Androgênios/administração & dosagem , Dopagem Esportivo , Inibinas/sangue , Detecção do Abuso de Substâncias/métodos , Testosterona/administração & dosagem , Levantamento de Peso , Adulto , Biomarcadores/sangue , Estudos de Casos e Controles , Ensaio de Imunoadsorção Enzimática , Hormônio Foliculoestimulante/sangue , Humanos , Hormônio Luteinizante/sangue , Masculino , Projetos Piloto , Testosterona/sangue
11.
Exp Clin Endocrinol Diabetes ; 127(2-03): 165-175, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30562824

RESUMO

Addison's disease - the traditional term for primary adrenal insufficiency (PAI) - is defined as the clinical manifestation of chronic glucocorticoid- and/or mineralocorticoid deficiency due to failure of the adrenal cortex which may result in an adrenal crisis with potentially life-threatening consequences. Even though efficient and safe pharmaceutical preparations for the substitution of endogenous gluco- and mineralocorticoids are established in therapy, the mortality in patients with PAI is still increased and the health-related quality of life (HRQoL) is often reduced.PAI is a rare disease but recent data report an increasing prevalence. In addition to the common "classical" causes of PAI like autoimmune, infectious, neoplastic and genetic disorders, other iatrogenic conditions - mostly pharmacological side effects (e. g., adrenal haemorrhage associated with anticoagulants, drugs affecting glucocorticoid synthesis, action or metabolism and some of the novel anti-cancer checkpoint inhibitors) are contributing factors to this phenomenon.Due to the rarity of the disease and often non-specific symptoms at least in the early stages, PAI is frequently not considered resulting in a delayed diagnosis. Successful therapy is mainly based on adequate patient education as a cornerstone in the prevention and management of adrenal crisis. A focus of current research is in the development of pharmacokinetically optimized glucocorticoid preparations as well as regenerative therapies.


Assuntos
Doença de Addison/diagnóstico , Doença de Addison/tratamento farmacológico , Doença de Addison/etiologia , Doença de Addison/epidemiologia , Humanos
12.
Biochem Biophys Res Commun ; 365(2): 316-21, 2008 Jan 11.
Artigo em Inglês | MEDLINE | ID: mdl-17986386

RESUMO

Selenoprotein P (SeP) is the major selenoprotein in human plasma, acting as an antioxidant and serving the transport of selenium from the liver to extrahepatic tissues. We here demonstrate that the human SeP promoter responds to overexpression of FoxO1a as well as of a constitutively active form of FoxO1a. Two FoxO-responsive elements were identified and characterized by generation of point mutation and deletion constructs. Similarly, SeP mRNA was upregulated in response to activation of FoxO1a in rat hepatoma cells stably transfected with a hydroxytamoxifen-regulatable form of FoxO1a. Insulin, stimulating the phosphorylation and inactivation of FoxO1a via phosphoinositide 3-kinase (PI3K) and Akt, suppressed SeP promoter activity and mRNA synthesis. This suppressive effect of insulin on SeP expression was attenuated by inhibitors of PI3K. In conclusion, the selenoprotein P promoter is a target of the Akt/FoxO signal transduction cascade and SeP expression is regulated at the level of transcription by the forkhead box protein FoxO1a in human and rat hepatoma cells.


Assuntos
Fatores de Transcrição Forkhead/metabolismo , Regiões Promotoras Genéticas/genética , Selenoproteína P/metabolismo , Fatores de Transcrição/metabolismo , Animais , Carcinoma Hepatocelular/genética , Carcinoma Hepatocelular/metabolismo , Linhagem Celular , Células Cultivadas , Proteína Forkhead Box O1 , Humanos , Ratos , Fatores de Transcrição/genética
15.
Trends Endocrinol Metab ; 16(4): 183-9, 2005.
Artigo em Inglês | MEDLINE | ID: mdl-15860415

RESUMO

There is increasing evidence that Forkhead box 'Other' (FoxO) proteins, a subgroup of the Forkhead transcription factor family, have an important role in mediating the effects of insulin and growth factors on diverse physiological functions, including cell proliferation, apoptosis and metabolism. Genetic studies in Caenorhabditis (Caenorhabditis elegans) and Drosophila demonstrate that FoxO proteins are ancient targets of insulin-like signaling involved in the regulation of metabolism and longevity. Studies in mammalian cells reveal that FoxO proteins regulate cell cycle progression and promote resistance to oxidative stress; both in vivo and cell culture studies support the concept that FoxO proteins have an important role in mediating the effects of insulin on metabolism, including its effects on hepatic glucose production. Phosphorylation and acetylation modulate FoxO function and control nuclear-cytoplasmic shuttling, DNA binding and protein-protein interactions. FoxO transcription factors exert positive and negative effects on gene expression, through direct binding to DNA target sites and protein-protein interactions with other transcription factors and coactivators. This paper provides an overview of studies leading to the identification of FoxO proteins as targets of insulin action and the mechanisms mediating the effects of insulin-like signaling on FoxO function, emphasizing the role of FoxO proteins in mediating the effects of insulin on metabolism.


Assuntos
Insulina/metabolismo , Insulina/fisiologia , Proteínas Nucleares/fisiologia , Fatores de Transcrição/fisiologia , Animais , DNA/metabolismo , Fatores de Transcrição Forkhead , Humanos , Proteínas Nucleares/química , Fosfatos de Fosfatidilinositol/fisiologia , Fatores de Transcrição/química
17.
Dtsch Med Wochenschr ; 141(12): 863-9, 2016 Jun.
Artigo em Alemão | MEDLINE | ID: mdl-27305302

RESUMO

The proprotein convertase subtilisin / kexin type 9 (PCSK9) plays an important role in LDL cholesterol (LDL-C) metabolism. Subjects harboring loss-of-function mutations in the gene encoding for PCSK9 display markedly reduced LDL-C plasma levels. PCSK9 is secreted by the liver, binds to the LDL receptor and, following endocytosis, induces lysosomal degradation of the receptor together with the bound LDL-C. Current PCSK9 inhibitors are monoclonal antibodies that specifically absorb PCSK9. Subsequently, instead of being degraded the receptor can dissociate from LDL-C and recycle, consecutively resulting in an increased hepatocyte LDL receptor density and higher LDL-C clearance. In clinical trials, the PCSK9 inhibitors alirocumab and evolocumab induced reductions in LDL-C of up to 70 % in statin-treated as well as statin-naïve patients. So far, serious side effects (requiring cessation of drug treatment) occurred only in rare cases. Since this new class of lipid lowering drugs promises a high potential benefit, they have been approved by the EMA even before completion of the studies addressing clinically relevant endpoints like cardiovascular events and mortality. Therefore, the expected publication of these study results in 2017 may allow a better assessment of the efficacy and safety of PCSK9 inhibitors.


Assuntos
Anticorpos Monoclonais/uso terapêutico , Anticolesterolemiantes/uso terapêutico , Doenças Cardiovasculares/sangue , Doenças Cardiovasculares/prevenção & controle , LDL-Colesterol/sangue , Hipercolesterolemia/sangue , Hipercolesterolemia/tratamento farmacológico , Inibidores de PCSK9 , Anticorpos Monoclonais/efeitos adversos , Anticorpos Monoclonais Humanizados , Anticolesterolemiantes/efeitos adversos , Aprovação de Drogas , Europa (Continente) , Humanos , Estados Unidos
18.
J Clin Endocrinol Metab ; 101(2): 364-89, 2016 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-26760044

RESUMO

OBJECTIVE: This clinical practice guideline addresses the diagnosis and treatment of primary adrenal insufficiency. PARTICIPANTS: The Task Force included a chair, selected by The Clinical Guidelines Subcommittee of the Endocrine Society, eight additional clinicians experienced with the disease, a methodologist, and a medical writer. The co-sponsoring associations (European Society of Endocrinology and the American Association for Clinical Chemistry) had participating members. The Task Force received no corporate funding or remuneration in connection with this review. EVIDENCE: This evidence-based guideline was developed using the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) system to determine the strength of recommendations and the quality of evidence. CONSENSUS PROCESS: The evidence used to formulate recommendations was derived from two commissioned systematic reviews as well as other published systematic reviews and studies identified by the Task Force. The guideline was reviewed and approved sequentially by the Endocrine Society's Clinical Guidelines Subcommittee and Clinical Affairs Core Committee, members responding to a web posting, and the Endocrine Society Council. At each stage, the Task Force incorporated changes in response to written comments. CONCLUSIONS: We recommend diagnostic tests for the exclusion of primary adrenal insufficiency in all patients with indicative clinical symptoms or signs. In particular, we suggest a low diagnostic (and therapeutic) threshold in acutely ill patients, as well as in patients with predisposing factors. This is also recommended for pregnant women with unexplained persistent nausea, fatigue, and hypotension. We recommend a short corticotropin test (250 µg) as the "gold standard" diagnostic tool to establish the diagnosis. If a short corticotropin test is not possible in the first instance, we recommend an initial screening procedure comprising the measurement of morning plasma ACTH and cortisol levels. Diagnosis of the underlying cause should include a validated assay of autoantibodies against 21-hydroxylase. In autoantibody-negative individuals, other causes should be sought. We recommend once-daily fludrocortisone (median, 0.1 mg) and hydrocortisone (15-25 mg/d) or cortisone acetate replacement (20-35 mg/d) applied in two to three daily doses in adults. In children, hydrocortisone (∼8 mg/m(2)/d) is recommended. Patients should be educated about stress dosing and equipped with a steroid card and glucocorticoid preparation for parenteral emergency administration. Follow-up should aim at monitoring appropriate dosing of corticosteroids and associated autoimmune diseases, particularly autoimmune thyroid disease.


Assuntos
Insuficiência Adrenal/diagnóstico , Insuficiência Adrenal/terapia , Medicina Baseada em Evidências , Feminino , Terapia de Reposição Hormonal/métodos , Humanos , Gravidez , Sociedades Médicas
19.
Mol Endocrinol ; 16(4): 859-72, 2002 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-11923481

RESUMO

Two predominant splice variants of the leptin receptor (LEPR) are coexpressed in leptin-responsive tissues: the long form, LEPRb, characterized as the signal-transducing receptor, and the signaling-defective short form, LEPRa. It is unknown whether heterodimers of these isoforms are capable of signal transduction via the Janus kinase (JAK)/signal transducer and activator of transcription (STAT) pathway. To address this question, chimeric receptors were constructed consisting of the transmembrane and intracellular parts of LEPRb and LEPRa fused with the extracellular domains of either the alpha- or beta-subunit of the IL-5 receptor. This strategy allows the directed heterodimerization of different LEPR cytoplasmic tails and excludes homodimerization. In COS-7 and HEPG2 cells, chimeric receptor heterodimers of LEPRa and LEPRb failed to activate the JAK/STAT pathway, whereas receptor dimers of LEPRb gave rise to the expected ligand-dependent activation of JAK2, phosphorylation of STAT3, and STAT3-dependent promoter activity. Markedly lower amounts of JAK2 were found to be associated with immunoprecipitated LEPRa chimeras than with LEPRb chimeras. Analysis of a series of deletion constructs indicated that a segment of 15 amino acids in addition to the 29 amino acids common to LEPRa and LEPRb was required for partial restoration of JAK/STAT activation. Site-directed mutagenesis of the critical sequence indicated that two hydrophobic residues (Leu896, Phe897) not present in LEPRa were indispensable for receptor signaling. These findings show that LEPRa/LEPRb heterodimers cannot activate STAT3 and identify sequence elements within the LEPR that are critical for the activation of JAK2 and STAT3.


Assuntos
Proteínas de Transporte/fisiologia , Proteínas de Ligação a DNA/metabolismo , Proteínas Tirosina Quinases/metabolismo , Proteínas Proto-Oncogênicas , Receptores de Superfície Celular , Transdução de Sinais/fisiologia , Transativadores/metabolismo , Ativação Transcricional , Sequência de Aminoácidos , Animais , Células COS , Proteínas de Transporte/química , Citoplasma/metabolismo , Análise Mutacional de DNA , Dimerização , Citometria de Fluxo , Janus Quinase 2 , Dados de Sequência Molecular , Fosforilação , Receptores para Leptina , Fator de Transcrição STAT3 , Relação Estrutura-Atividade
20.
Biochem J ; 382(Pt 2): 471-9, 2004 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-15167811

RESUMO

The key insulin-regulated gluconeogenic enzyme G6Pase (glucose-6-phosphatase) has an important function in the control of hepatic glucose production. Here we examined the inhibition of G6Pase gene transcription by TNF (tumour necrosis factor) in H4IIE hepatoma cells. TNF decreased dexamethasone/dibtuyryl cAMP-induced G6Pase mRNA levels. TNFalpha, but not insulin, led to rapid activation of NFkappaB (nuclear factor kappaB). The adenoviral overexpression of a dominant negative mutant of IkappaBalpha (inhibitor of NFkappaB alpha) prevented the suppression of G6Pase expression by TNFalpha, but did not affect that by insulin. The regulation of G6Pase by TNF was not mediated by activation of the phosphoinositide 3-kinase/protein kinase B pathway, extracellular-signal-regulated protein kinase or p38 mitogen-activated protein kinase. Reporter gene assays demonstrated a concentration-dependent down-regulation of G6Pase promoter activity by the transient overexpression of NFkappaB. Although two binding sites for NFkappaB were identified within the G6Pase promoter, neither of these sites, nor the insulin response unit or binding sites for Sp proteins, was necessary for the regulation of G6Pase promoter activity by TNFalpha. In conclusion, the data indicate that the activation of NFkappaB is sufficient to suppress G6Pase gene expression, and is required for the regulation by TNFalpha, but not by insulin. We propose that NFkappaB does not act by binding directly to the G6Pase promoter.


Assuntos
Glucose-6-Fosfatase/antagonistas & inibidores , Glucose-6-Fosfatase/genética , NF-kappa B/fisiologia , Fatores de Necrose Tumoral/fisiologia , Animais , Carcinoma Hepatocelular/patologia , Linhagem Celular Tumoral , DNA de Neoplasias/metabolismo , Proteínas de Ligação a DNA/metabolismo , Regulação Enzimológica da Expressão Gênica/fisiologia , Regulação Neoplásica da Expressão Gênica/fisiologia , Insulina/fisiologia , Neoplasias Hepáticas/patologia , NF-kappa B/metabolismo , Regiões Promotoras Genéticas/genética , Ratos , Elementos de Resposta/genética , Transcrição Gênica/fisiologia , Ativação Transcricional/fisiologia
SELEÇÃO DE REFERÊNCIAS
Detalhe da pesquisa