RESUMO
ß-Glucan is a homopolymer with a backbone of ß-1,3-linked glucose residues. The solubility and biological activity of ß-glucan can be influenced by the length of the backbone and the length/interval of the ß-1,6 branches. Dectin-1 is crucial in innate immunity through its binding to exogenous ß-glucans. However, there are few quantitative binding affinities available and there is no comprehensive comparative analysis of the binding of Dectin-1 to insoluble ß-glucans. Here, we have developed a simple binding assay for the interaction between Dectin-1 lectin domain (Dectin-1 CTLD) and insoluble ß-glucans. We utilized the paramylon particle as a model of insoluble ß-glucans. Dectin-1 CTLD bound to paramylon (particle size 3.1 µm) was separated from unbound Dectin-1 CTLD by centrifugation using a membrane filter (pore size 0.2 µm). The protein in the filtrate was quantified by SDS-PAGE and densitometry. The amount decreased in proportion to the amount of paramylon in the mixture. A control experiment using the Dectin-1 CTLD inactive mutant W221A showed that the mutant passes through the filter without binding paramylon. These results are evidence of site-specific binding of Dectin-1 CTLD to paramylon and demonstrate that the separation of paramylon-bound/unbound Dectin-1 CTLD is achievable through centrifugation using a filter. The assay was extended to other insoluble ß-glucans including curdlan. Additionally, it can be utilized in competitive inhibition experiments with soluble short-chain ß-glucans such as laminarin. The assay system allows for quantitative comparison of the affinities between insoluble and soluble ß-glucans and Dectin-1 CTLD, and should be useful because of its low-tech convenience.
Assuntos
beta-Glucanas , beta-Glucanas/química , Lectinas Tipo C/genética , Lectinas Tipo C/química , Imunidade InataRESUMO
To investigate whether supplementation of paramylon (PM)-rich Euglena gracilis EOD-1 powder (EOD-1) reduces visceral fat obesity in moderately obese Japanese subjects. A randomized, double-blind, placebo-controlled intervention study was conducted involving 36 Japanese adults with a body mass index (BMI) ≥25 and <30 kg/m2. Subjects were randomly assigned into two groups to consume EOD-1 capsules (EOD-1 group, 2.6 g PM/day) or cellulose capsules (placebo group) for a 12-week period. Anthropometric measurements including visceral fat area (VFA) and blood samples were measured at baseline and throughout the trial. There was no significant difference in VFA between the two groups, although subgroup analysis by gender showed a significant decrease in VFA in the male EOD-1 group compared with the placebo group. Serum adiponectin levels in all subjects from the EOD-1 group were significantly higher than in the placebo group. By comparison with the placebo group, the subjects in the EOD-1 group showed a significant reduction in serum HbA1c levels. EOD-1 intake led to a significant reduction in VFA in male subjects with moderate obesity (BMI 25-30 kg/m2). PM in EOD-1 may contribute to preventing visceral fat obesity in male Japanese subjects. Moreover, PM may also contribute to improving glucose homeostasis in moderately obese Japanese adults.
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Euglena gracilis, a type of microalgae, contains several nutrients and accumulates paramylon, a ß-1,3-glucan. In recent studies, paramylon has shown to exhibit various activities including immunomoduratory and hepatoprotective effects. In the present study, using an in vitro cell culture system, we aimed to determine whether paramylon derived from the E. gracilis EOD-1 strain, which produces large amounts of paramylon, can augment SIRT1 expression in epidermal cells via activating gut-skin interactions. Results showed that paramylon augmented the expression of SIRT1 in Caco-2 cells, a human intestinal cell line. Furthermore, microarray analysis of Caco-2 cells treated with paramylon showed that paramylon activates epidermal cells through inducing the secretion of factors from intestinal cells. Then, we focused on skin cells as target cells of paramylon-activated intestinal cells. Results showed that secretory factors from Caco-2 cells treated with paramylon augmented the expression of SIRT1 in HaCaT cells, a human keratinocyte cell line, and that expression level of genes related to the growth and maintenance of epidermal cells were significantly changed in Caco-2 cells treated with paramylon as evidenced by microarray analysis. All these results suggest that paramylon can activate epidermal cells by inducing the production of secretory factors from intestinal cells.
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Menin is lost by the sequential inactivation of both MEN1 alleles in subsets of non-hereditary endocrine tumors as well as those associated with multiple endocrine neoplasia type 1 (MEN1), an autosomal dominant hereditary cancer syndrome characterized by multiple tumors including parathyroid, pituitary and enteropancreatic endocrine tumors. Loss of menin has been reported to be associated with lowered caspase 8 expression and resistance to apoptosis in murine fibroblasts and in pancreatic islet tumors arising in heterozygous MEN1 gene knockout mice, the animal model of the human MEN1 syndrome. We confirmed by menin-knockdown experiments with specific siRNA that menin is crucial for caspase 8 expression in human culture cells while overexpression of menin did not increase caspase 8 protein over basal levels. We then examined expression of menin, caspase 8 and cyclin-dependent kinase inhibitors p27(Kip1) and p15(Ink4b) by Western blotting in human parathyroid tumors surgically resected from patients with MEN1 and those with non-hereditary primary hyperparathyroidism. The menin and p27(Kip1) expression levels were correlated with MEN1 mutation status that was confirmed by DNA analysis. The caspase 8 and p15(Ink4b) protein levels were variable among tumors, and were not correlated with menin protein levels. These findings suggest that human endocrine tumors lacking menin may not always exhibit lowered caspase 8 expression and hence may not be resistant to apoptosis-inducing therapy.
Assuntos
Caspase 8/biossíntese , Neoplasia Endócrina Múltipla Tipo 1/metabolismo , Neoplasias das Paratireoides/fisiopatologia , Proteínas Proto-Oncogênicas/biossíntese , Inibidor de Quinase Dependente de Ciclina p15/metabolismo , Inibidor de Quinase Dependente de Ciclina p27/biossíntese , Células HEK293 , Humanos , Neoplasia Endócrina Múltipla Tipo 1/genética , Proteínas Proto-Oncogênicas/genéticaRESUMO
Euglena gracilis EOD-1, a kind of microalgae, is known to contain a high proportion of paramylon, a type of ß-1,3-glucan. Paramylon derived from E. gracilis EOD-1 is presumed to suppress cellular oxidative injury and expected to reduce fatigue and fatigue sensation. Therefore, we aimed to examine whether food containing paramylon derived from E. gracilis EOD-1 (EOD-1PM) ingestion reduced fatigue and fatigue sensation in healthy adults. We conducted a randomized, double-blind, placebo-controlled, parallel-group comparison study in 66 healthy men and women who ingested a placebo or EOD-1PM daily for 4 weeks (daily life fatigue). Furthermore, at the examination days of 0 and 4 weeks, tolerance to fatigue load was evaluated using mental tasks (task-induced fatigue). We evaluated fatigue sensation using the Visual Analogue Scale, the work efficiency of the advanced trail making test and measured serum antioxidant markers. The EOD-1PM group showed significantly lower levels of physical and mental fatigue sensations and higher levels of work efficiency as well as serum biological antioxidant potential levels than the placebo group. These results indicate that EOD-1PM ingestion reduced fatigue and fatigue sensation, which may be due to an increase in antioxidant potential and maintenance of selective attention during work.
Assuntos
Fadiga/dietoterapia , beta-Glucanas/administração & dosagem , beta-Glucanas/análise , Adulto , Antioxidantes/administração & dosagem , Sistema Nervoso Autônomo/efeitos dos fármacos , Biomarcadores/sangue , Método Duplo-Cego , Euglena gracilis , Feminino , Inocuidade dos Alimentos , Glucanos , Humanos , Masculino , Pessoa de Meia-Idade , Estresse Oxidativo/efeitos dos fármacos , Adulto JovemRESUMO
Tenascin-C (TNC) is an extracellular matrix protein that is transiently expressed in close association with tissue remodeling in various organs. Expression of TNC in patients with tubulointerstitial nephritis (TIN) is not well-characterized. Using renal biopsy specimens from 25 patients with TIN and 8 patients with thin basement membrane disease (controls), we assessed immunohistochemical staining for TNC and investigated its relation with clinicopathologic data. TNC was undetectable in the controls, but TNC was observed in the interstitium of specimens from all patients with TIN, and strong TNC staining was detected within active tubulitis lesions. TNC was not principally expressed in glomeruli, and it was also absent from scar tissue. Comparison with Sirius red staining revealed that TNC was present where collagen fibers had not yet formed. The percent area of TNC within the interstitium (% TNC-positive area) showed a significant negative correlation with illness duration and significant positive correlations with the serum CRP level and eGFR aggravation, both of which reflect disease activity. On the other hand, no correlation was found between % TNC-positive area and eGFR recovery during 2 years of follow up. Examination of renal biopsy specimens from TIN patients revealed that TNC appears during the active stage of inflammation and then disappears with healing. This suggests that TNC expression reflects TIN disease activity, but not prognosis.
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BACKGROUND: Paget-Schroetter syndrome (PSS) is an unusual cause of venous thromboembolism, which is frequently misdiagnosed and undiagnosed in clinical settings. Although axillary-subclavian vein thrombosis is related with PSS typically presents in healthy young athletes, it is possible for this phenomenon to occur in various age settings. CASE SUMMARY: We present a case of recurrent pulmonary embolism caused by a thrombus in dilated axillary vein related with PSS. A 74-year-old man was referred to our cardiology department for chest discomfort and hypoxaemia. The contrast computed tomography (CT) revealed that he suffered from bilateral pulmonary embolism. However, we could not find the source of embolism despite other examinations such as ultrasonography of the inferior limb deep vein. Three months later, the patient complained of dyspnoea for a second time, and a contrast CT scan was subsequently performed revealing a new pulmonary embolism. Surgical resection of the giant thrombus was performed, resulting in a good clinical course without recurrence. DISCUSSION: We experienced a case of recurring pulmonary embolism in a patient with undiagnosed PSS, which was related to the active and vigorous movement of the right arm during his working. Although there are various treatments for PSS including anticoagulation, first rib resection, and lifestyle modification, we need to consider what is the best treatment individually.
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Background: Levocarnitine has been reported to improve the left ventricular (LV) systolic function and decrease LV hypertrophy in hemodialysis (HD) patients. Its effect on LV diastolic dysfunction, however, has not yet been clarified. MethodsâandâResults: HD patients (n=88) were given levocarnitine i.v. 1,000 mg for 12 months at the end of every dialysis session through the dialysis circuit of the venous site. LV ejection fraction (EF), E/A, E/e', left atrial volume index (LAVI) and LV mass index (LVMI) were measured before and 3, 6, 9, and 12 months after the start of levocarnitine on echocardiography. We regarded E/A≤0.8, E/e'>14 and LAVI>34 mL/m2 as LV diastolic dysfunction, and LVEF<55% as LV systolic dysfunction. We also investigated the effect of levocarnitine on HFpEF. Plasma brain natriuretic peptide, total carnitine, free carnitine, and acyl-carnitine and biochemistry parameters were measured. Levocarnitine significantly improved LV diastolic function in HD patients with LV diastolic dysfunction, but did not affect LV diastolic function in those with normal LV diastolic function. Levocarnitine significantly improved HFpEF. Levocarnitine significantly improved the LV systolic function in HD patients with LV systolic dysfunction but did not affect the LV systolic function in those with normal LV systolic function. Levocarnitine significantly decreased LVMI and increased plasma total, free, and acyl-carnitine. Conclusions: Levocarnitine ameliorates LV diastolic as well as LV systolic dysfunction in HD patients.
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Controversy still exists about whether vitamin D status is related to the severity of primary hyperparathyroidism (pHPT), although vitamin D insufficiency is frequent in pHPT. The present study was therefore performed to examine the relationships between vitamin D status and various parameters in 30 postmenopausal pHPT patients. BMD values were measured by dual-energy x-ray absorptiometry at the lumbar spine (L(2-4)), femoral neck (FN) and distal one third of the radius (Rad 1/3). Serum levels of 25 hydroxy-vitamin D(3) [25(OH)D] and 1,25-dihydroxy vitamin D(3) [1,25(OH) (2)D(3)] were 15.8 +/- 3.5 microg/l and 69.3 +/- 33.3 ng/l in pHPT patients, respectively. Serum levels of calcium and PTH seemed to be negatively correlated to serum 25(OH)D levels, although the differences were not significant. However, when subjects with the highest serum PTH levels (PTH>1000 pg/ml) were excluded from the analysis, the correlation was significant between serum 25(OH)D levels and PTH, indicating that vitamin D status affects the severity of pHPT when severe cases were excluded. In addition, serum levels of 1,25(OH)(2)D(3) were significantly and negatively correlated to serum 25(OH)D levels. On the other hand, serum levels of 25(OH)D were significantly and positively correlated to BMD (Z-score) at the lumbar spine, but not at the radius and femoral neck; however, serum 25(OH)D levels were not correlated to the levels of any bone metabolic indices measured. Moreover, serum levels of 25(OH)D were not related to urinary calcium and the tubular reabsorption rate of phosphorus, and they were similar in groups with and without renal stones. In conclusion, vitamin D status seemed to be related to the severity of disease in postmenopausal patients with pHPT. In particular, the relationship between serum 25(OH)D level and BMD at the lumbar spine was predominant.
Assuntos
Doenças Ósseas Metabólicas/etiologia , Hiperparatireoidismo Primário/sangue , Osteoporose Pós-Menopausa/etiologia , Vitamina D/sangue , Idoso , Densidade Óssea , Doenças Ósseas Metabólicas/sangue , Osso e Ossos/metabolismo , Estudos de Casos e Controles , Estudos Transversais , Feminino , Humanos , Hiperparatireoidismo Primário/complicações , Cálculos Renais/sangue , Cálculos Renais/complicações , Pessoa de Meia-Idade , Osteoporose Pós-Menopausa/sangue , Pós-Menopausa/sangueRESUMO
PTH, via the PTH/PTH-related protein receptor type 1 that couples to both protein kinase A (PKA) and protein kinase C (PKC) pathways, and the canonical Wnt-beta-catenin signaling pathway play important roles in bone formation. In the present study we have examined the interaction between the PTH and Wnt signaling pathways in mouse osteoblastic MC3T3-E1 cells. PTH dose- and time-dependently increased the concentrations of beta-catenin. The PKA activator, forskolin, and the PKC activator, phorbol 12-myristate-13-acetate, as well as the PTH analog, [Nle(8,18),Tyr(34)]human PTH-(3-34)amide, all increased beta-catenin levels. Both H-89, a specific PKA inhibitor, and PKC inhibitors, staurosporine and calphostin C, antagonized PTH stimulation of beta-catenin levels. TGF-beta as well as transfection of the TGF-beta-signaling molecule, Smad3, enhanced beta-catenin levels, and this was antagonized by transfection of a dominant-negative Smad3. The transcriptional activity of transfected dominant-active beta-catenin was enhanced by PTH, an effect that was antagonized by cotransfection of a dominant-negative Smad3. PTH as well as LiCl(2), which mimics the effects of the Wnt-beta-catenin pathway, rescued the dexamethasone- and etoposide-induced apoptosis of osteoblastic cells. In conclusion, the data demonstrate that PTH stimulates osteoblast beta-catenin levels via Smad3, and that both PKA and PKC pathways are involved. The canonical Wnt-beta-catenin pathway is likely to be involved in the antiapoptotic actions of PTH by acting through Smad3 in osteoblasts.
Assuntos
Regulação da Expressão Gênica , Osteoblastos/citologia , Hormônio Paratireóideo/fisiologia , Proteína Smad3/metabolismo , beta Catenina/metabolismo , Animais , Apoptose , Desenvolvimento Ósseo , Osso e Ossos/metabolismo , Linhagem Celular Tumoral , Células Cultivadas , Proteínas Quinases Dependentes de AMP Cíclico/metabolismo , Dexametasona/farmacologia , Inibidores Enzimáticos/farmacologia , Etoposídeo/farmacologia , Isoquinolinas/farmacologia , Cloreto de Lítio/farmacologia , Luciferases/metabolismo , Camundongos , Células NIH 3T3 , Naftalenos/farmacologia , Osteoblastos/metabolismo , Hormônio Paratireóideo/metabolismo , Proteína Quinase C/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Transdução de Sinais , Estaurosporina/farmacologia , Sulfonamidas/farmacologia , Acetato de Tetradecanoilforbol/farmacologia , Fatores de Tempo , Transfecção , Fator de Crescimento Transformador beta/metabolismoRESUMO
Central in the pathogenesis of glucocorticoid (GC)-induced osteoporosis is the effects of GC on bone formation. However, the mechanism of GC-inhibited bone formation is not well known. Transforming growth factor (TGF)-beta is most abundant in bone matrix compared with other tissues, and we have recently proposed that Smad3, a TGF-beta signaling molecule, is important for promoting bone formation. However, no reports have been available about the effects of GC on Smad3 in osteoblasts. In the present study, we investigated whether dexamethasone (Dex), an active GC analog, would affect the expression and activity of Smad3 in mouse osteoblastic MC3T3-E1 and rat osteoblastic UMR-106 cells. Dex significantly suppressed Smad3-stimulated alkaline phosphatase (ALP) activity, although it did not affect TGF-beta-inhibited ALP activity in MC3T3-E1 cells. Moreover, pretreatment with Dex suppressed TGF-beta-enhanced expression of type I collagen in MC3T3-E1 and UMR-106 cells. In the luciferase assay using p3TP-Lux with a Smad3-specific response element, Dex significantly suppressed the transcriptional activity induced by TGF-beta as well as Smad3. However, Dex did not affect the expression of Smad3 in these cells at both mRNA and protein levels. In conclusion, the present study indicates that Dex inhibits ALP activity and type I collagen expression, presumably by suppressing Smad3-induced transcriptional activity but not by modulating Smad3 expression in osteoblastic cells.
Assuntos
Proteínas de Ligação a DNA/metabolismo , Dexametasona/farmacologia , Glucocorticoides/farmacologia , Osteoblastos/metabolismo , Transativadores/metabolismo , Fosfatase Alcalina/metabolismo , Animais , Western Blotting/métodos , Linhagem Celular , Colágeno Tipo I/metabolismo , Proteínas de Ligação a DNA/análise , Proteínas de Ligação a DNA/genética , Depressão Química , Camundongos , Osteoblastos/efeitos dos fármacos , RNA Mensageiro/análise , Ratos , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Proteína Smad3 , Transativadores/análise , Transativadores/genética , Transfecção/métodos , Fator de Crescimento Transformador beta/metabolismoRESUMO
A 59-year-old man developed pneumonia 9 days after bathing in a hot spring spa. Bilateral shadows on his chest radiograph rapidly progressed after admission. He was successfully treated with erythromycin and rifampicin. Legionella pneumophila serogroup 6 was recovered from an intratrachial specimen and a significant elevation was observed in a paired indirect fluorescent antibody to Legionella. Persistent slight fever and chest rentogenographic shadows resolved after administering low-dose prednisolone to treat organizing pneumonia shown by transbronchial lung biopsy. The same serotype of Legionella was recovered from the water of the hot spring spa where the man had bathed. When the extracted DNA of these two strains showed identical restriction fragments by pulsed-field gel electrophoresis, we had direct evidence that hot spring spas can be a source of Legionella pneumonia.
Assuntos
Banhos/efeitos adversos , DNA Bacteriano/análise , Reservatórios de Doenças , Legionella pneumophila/isolamento & purificação , Doença dos Legionários/microbiologia , Microbiologia da Água , Antibacterianos/uso terapêutico , Antibióticos Antituberculose/uso terapêutico , Eletroforese em Gel de Campo Pulsado , Eritromicina/uso terapêutico , Genes Bacterianos , Humanos , Legionella pneumophila/genética , Doença dos Legionários/diagnóstico por imagem , Doença dos Legionários/tratamento farmacológico , Pulmão/patologia , Masculino , Pessoa de Meia-Idade , Radiografia Torácica , Rifampina/uso terapêutico , Resultado do TratamentoAssuntos
Neoplasias do Ventrículo Cerebral/complicações , Ependimoma/complicações , Neoplasia Endócrina Múltipla Tipo 1/complicações , Neoplasias Primárias Múltiplas , Neoplasias da Medula Espinal/complicações , Adulto , Neoplasias do Ventrículo Cerebral/diagnóstico , Neoplasias do Ventrículo Cerebral/cirurgia , Códon sem Sentido , Ependimoma/diagnóstico , Ependimoma/cirurgia , Humanos , Hiperplasia/etiologia , Imageamento por Ressonância Magnética , Masculino , Neoplasia Endócrina Múltipla Tipo 1/diagnóstico , Neoplasia Endócrina Múltipla Tipo 1/genética , Neoplasia Endócrina Múltipla Tipo 1/cirurgia , Glândulas Paratireoides/patologia , Proteínas Proto-Oncogênicas/genética , Neoplasias da Medula Espinal/diagnóstico , Neoplasias da Medula Espinal/cirurgiaRESUMO
Bisphosphonate is an effective drug to reduce fracture risk in osteoporotic patients; however, factors affecting the efficacy of bisphosphonate treatment are not fully known, especially in Japanese patients. In the present study, we examined the relationships between an increase in lumbar spine bone mineral density (BMD) by bisphosphonates and several pretreatment parameters, including biochemical, bone/mineral, and body composition indices, in 85 postmenopausal osteoporotic patients treated with alendronate or risedronate. BMD increase was measured by dual-energy X-ray absorptiometry at the lumbar spine before and 2 years after treatment. BMD increase at the lumbar spine was observed as independent of age, height, weight, body mass index, and fat mass, although lean body mass seemed slightly related. On the other hand, fasting plasma glucose (FPG) levels were significantly and positively related to BMD increase at the lumbar spine. In multiple regression analysis, FPG levels were not significantly related to BMD increase at the lumbar spine when lean body mass was considered. As for bone/mineral parameters, BMD increase at the lumbar spine was not significantly related to serum levels of calcium, parathyroid hormone (PTH), and alkaline phosphatase or urinary levels of deoxypiridinoline and calcium excretion. As for BMD parameters, Z-scores of BMD at any site and bone geometry parameters obtained by forearm peripheral quantitative computed tomography were not significantly related to BMD increase at the lumbar spine. BMD increases at the lumbar spine were similar between groups with or without vertebral fractures. In conclusion, BMD increase at the lumbar spine by bisphosphonate treatment was not related to any pretreatment parameters, including body size, body composition, and bone/mineral metabolism in postmenopausal Japanese women with primary osteoporosis, although FPG correlated partly to BMD through lean body mass.
Assuntos
Conservadores da Densidade Óssea , Densidade Óssea , Difosfonatos , Vértebras Lombares , Osteoporose Pós-Menopausa , Absorciometria de Fóton , Idoso , Idoso de 80 Anos ou mais , Conservadores da Densidade Óssea/farmacologia , Conservadores da Densidade Óssea/uso terapêutico , Difosfonatos/farmacologia , Difosfonatos/uso terapêutico , Feminino , Humanos , Vértebras Lombares/anatomia & histologia , Vértebras Lombares/efeitos dos fármacos , Pessoa de Meia-Idade , Osteoporose Pós-Menopausa/tratamento farmacológico , Osteoporose Pós-Menopausa/patologiaRESUMO
Von Hippel-Lindau (VHL) syndrome is a neoplastic syndrome caused by a mutation in the VHL gene. There is a discrepancy between the phenotypes of human VHL syndrome and VHL gene-disrupted mouse models. A heterozygous VHL gene-disrupted model (vhl +/-) developed hepatic vascular lesions; in contrast, hepatic hemangioma is a rare manifestation of human VHL syndrome. We identified a novel mutation (P154S) in the VHL gene in a Japanese family with pheochromocytoma. One of the members demonstrated hepatic hemangiomas, suggesting that there may be a relationship between the mutation of the VHL gene and hepatic vascular lesions, even in humans.
Assuntos
Neoplasias das Glândulas Suprarrenais/genética , Hemangioma/genética , Neoplasias Hepáticas/genética , Neoplasias Primárias Múltiplas/genética , Feocromocitoma/genética , Proteína Supressora de Tumor Von Hippel-Lindau/genética , Neoplasias das Glândulas Suprarrenais/diagnóstico por imagem , Idoso , Povo Asiático/genética , Hemangioma/diagnóstico por imagem , Humanos , Neoplasias Hepáticas/diagnóstico por imagem , Masculino , Mutação de Sentido Incorreto , Linhagem , Feocromocitoma/diagnóstico por imagem , Polimorfismo de Fragmento de Restrição , Tomografia Computadorizada por Raios XRESUMO
In some patients with multiple endocrine neoplasia type 1 (MEN1) it is not possible to identify a germline mutation in the MEN1 gene. We sought to document the loss of expression and function of the MEN1 gene product, menin, in the tumors of such a patient. The proband is an elderly female patient with primary hyperparathyroidism, pancreatic islet tumor, and breast cancer. Her son has primary hyperparathyroidism. No germline MEN1 mutation was identified in the proband or her son. However, loss of heterozygosity at the MEN1 locus and complete lack of menin expression were demonstrated in the proband's tumor tissue. The proband's cultured parathyroid cells lacked the normal reduction in proliferation and parathyroid hormone secretion in response to transforming growth factor- beta. This assessment provided insight into the molecular pathogenesis of the patient and provides evidence for a critical requirement for menin in the antiproliferative action of transforming growth factor-beta.
Assuntos
Cromossomos Humanos Par 11 , Mutação em Linhagem Germinativa/fisiologia , Perda de Heterozigosidade , Neoplasia Endócrina Múltipla Tipo 1/genética , Neoplasia Endócrina Múltipla Tipo 1/metabolismo , Proteínas Proto-Oncogênicas/genética , Proteínas Proto-Oncogênicas/metabolismo , Idoso , Feminino , Humanos , Hipercalcemia/etiologia , Hipertireoidismo/diagnóstico , Hipertireoidismo/genética , Neoplasias Hepáticas/diagnóstico , Repetições de Microssatélites , Neoplasia Endócrina Múltipla Tipo 1/patologia , Neoplasia Endócrina Múltipla Tipo 1/secundário , Hormônio Paratireóideo/metabolismo , Neoplasias das Paratireoides/metabolismo , Neoplasias das Paratireoides/patologia , Polimorfismo Genético , Proteínas Proto-Oncogênicas/fisiologia , Fator de Crescimento Transformador beta/metabolismo , Células Tumorais CultivadasRESUMO
Mice null for menin, the product of the multiple endocrine neoplasia type 1 (MEN1) gene, exhibit cranial and facial hypoplasia suggesting a role for menin in bone formation. We have shown previously that menin is required for the commitment of multipotential mesenchymal stem cells into the osteoblast lineage in part by interacting with the bone morphogenetic protein (BMP)-2 signaling molecules Smad1/5, and the key osteoblast transcriptional regulator, Runx2 (Sowa H., Kaji, H., Hendy, G. N., Canaff, L., Komori, T., Sugimoto, T., and Chihara, K. (2004) J. Biol. Chem. 279, 40267-40275). However, menin inhibits the later differentiation of committed osteoblasts. The activator protein-1 (AP-1) transcription factor, JunD, is expressed in osteoblasts and has been shown to interact with menin in other cell types. Here, we examined the consequences of menin-JunD interaction on osteoblast differentiation in mouse osteoblastic MC3T3-E1 cells. JunD expression, assessed by immunoblot, gradually increased during osteoblast differentiation. Stable expression of JunD enhanced expression of the differentiation markers, Runx2, type 1 collagen (COL1), and osteocalcin (OCN) and alkaline phosphatase (ALP) activity and mineralization. Hence, JunD promotes osteoblast differentiation. In MC3T3-E1 cells in which menin expression was reduced by stable menin antisense DNA transfection, JunD levels were increased. When JunD and menin were co-transfected in MC3T3-E1 cells, they co-immunoprecipitated. JunD overexpression increased the transcriptional activity of an AP-1 luciferase reporter construct, and this activity was reduced by co-transfection of menin. Therefore, JunD and menin interact both physically and functionally in osteoblasts. Furthermore, menin overexpression inhibited the ALP activity induced by JunD. In conclusion, the data suggest that menin suppresses osteoblast maturation, in part, by inhibiting the differentiation actions of JunD.
Assuntos
Osteoblastos/citologia , Proteínas Proto-Oncogênicas c-jun/fisiologia , Proteínas Proto-Oncogênicas/química , Proteínas Proto-Oncogênicas/fisiologia , Fator de Transcrição AP-1/metabolismo , Fosfatase Alcalina/metabolismo , Animais , Northern Blotting , Western Blotting , Proteína Morfogenética Óssea 2 , Proteínas Morfogenéticas Ósseas/metabolismo , Diferenciação Celular , Linhagem Celular , DNA Complementar/metabolismo , Humanos , Imunoprecipitação , Luciferases/metabolismo , Camundongos , Oligonucleotídeos Antissenso/química , Osteoblastos/metabolismo , Plasmídeos/metabolismo , Ligação Proteica , Proteínas Proto-Oncogênicas c-jun/metabolismo , RNA/química , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Transdução de Sinais , Transcrição Gênica , Transfecção , Fator de Crescimento Transformador beta/metabolismoRESUMO
Glucocorticoid (GC)-induced osteoporosis (GIO) is frequently seen in patients with excessive GC. Numerous questions remain to be clarified about the pathogenesis and treatment of GIO, and the mechanism of GC-inhibited bone formation is not well known. Several studies suggest that parathyroid hormone (PTH) and hormone replacement therapy are effective for GIO. We therefore investigated whether PTH and estrogen would affect cell proliferation and alkaline phosphatase (ALP) activity inhibited by dexamethasone (Dex) in mouse osteoblastic cell-line MC3T3-E1 cells. Low-dose (10(-11) M) PTH as well as 10(-8) M 17-beta-estradiol (17beta-E2) significantly attenuated Dex-inhibited ALP activity, although 10(-8) M PTH did not affect it. ICI 182780 (10(-8) M) antagonized the effects of 17beta-E(2) on Dex-suppressed ALP activity. Neutralizing anti-IGF-I antibody (3 microg/ml) blocked the reverse effects of 17beta-E2 on ALP activity suppressed by Dex. PTH (10(-11) M), but not 17beta-E2, significantly attenuated [3H]thymidine incorporation inhibited by Dex. On the other hand, PTH and estrogen did not affect the level of 11-beta-hydrosteroid dehydrogenase type I mRNA increased by Dex. In conclusion, the present study demonstrated that low-dose PTH and estrogen reversed Dex-inhibited ALP activity in the mouse osteoblastic cell-line.