RESUMEN
Previous studies demonstrated that the liganded vitamin D receptor (VDR) plays an important role in controlling cardiovascular homeostasis. Both the whole animal VDR gene knockout (VDR-/-) and the myocyte-specific VDR gene deletion result in changes in cardiac structure and function. Clinical states associated with cardiac steatosis (obesity and diabetes mellitus) are also associated with low circulating 25 OH vitamin D levels. We, therefore, examined the effects of VDR deficiency (VDR-/- mouse) in a murine model of cardiac steatosis that expresses the terminal enzyme involved in triglyceride synthesis, diacylglycerol acyltransferase 1 (DGAT1), selectively in the cardiac myocyte. These mice display early cardiac dysfunction and late cardiomyopathy and heart failure. In the present study, we demonstrate that mice harboring both genetic modifications (i.e., MHC-DGAT1 Tg and VDR-/-) exhibit an increase in myocyte size, heart weight/body weight ratio and natriuretic peptide gene expression, all markers of cardiac hypertrophy, that exceed that seen in either VDR-/- or the MHC-DGAT1 Tg mice alone. This was accompanied by a dramatic increase in interstitial fibrosis and increased expression of collagen 1a1 and collagen 3a1, as well as the osteopontin and matrix metalloproteinase 2, genes. At a functional level, this resulted in a 37% reduction in ejection fraction and 55% reduction in fractional shortening in the DGAT1; VDR-/- mice relative to the controls. Collectively, these data demonstrate that deficiency in the vitamin D signaling system enhances the pathological phenotype in this experimental cardiomyopathy and suggest an important role for vitamin D in modulating disease severity in common cardiovascular disorders.
Asunto(s)
Cardiomiopatías/genética , Diacilglicerol O-Acetiltransferasa/genética , Insuficiencia Cardíaca/genética , Miocitos Cardíacos/metabolismo , Receptores de Calcitriol/genética , Animales , Peso Corporal , Cardiomiopatías/metabolismo , Cardiomiopatías/patología , Tamaño de la Célula , Colágeno Tipo I/genética , Colágeno Tipo I/metabolismo , Colágeno Tipo III/genética , Colágeno Tipo III/metabolismo , Diacilglicerol O-Acetiltransferasa/metabolismo , Venenos Elapídicos/genética , Venenos Elapídicos/metabolismo , Fibrosis , Insuficiencia Cardíaca/metabolismo , Insuficiencia Cardíaca/patología , Masculino , Metaloproteinasa 2 de la Matriz/genética , Metaloproteinasa 2 de la Matriz/metabolismo , Ratones , Ratones Noqueados , Miocitos Cardíacos/patología , Péptido Natriurético Tipo-C/genética , Péptido Natriurético Tipo-C/metabolismo , Osteopontina/genética , Osteopontina/metabolismo , Receptores de Calcitriol/deficiencia , Volumen SistólicoRESUMEN
A variety of studies have suggested that vitamin D may play a palliative role in improving insulin secretion and glucose tolerance. Endothelial cells of the microcirculation are thought to play an important role in regulating both insulin secretion and insulin sensitivity in target tissues. We have selectively deleted the vitamin D receptor (VDR) gene in endothelial cells of the murine vasculature. These mice demonstrate improved glucose tolerance, improved insulin sensitivity in skeletal muscle, but not in liver, and a reduction in expression and secretion of insulin in the pancreatic islets. Collectively, these data, taken within the context of recent publications in this field, suggest that the endothelial cell VDR plays a tonic inhibitory role in regulating glucose disposal and could prove to be a factor in controlling glucose homeostasis in the intact organism.
Asunto(s)
Células Endoteliales/metabolismo , Glucosa/metabolismo , Insulina/metabolismo , Músculo Esquelético/metabolismo , Receptores de Calcitriol/genética , Vitamina D/metabolismo , Animales , Regulación de la Expresión Génica , Prueba de Tolerancia a la Glucosa , Homeostasis , Resistencia a la Insulina , Islotes Pancreáticos/metabolismo , Hígado/metabolismo , Ratones , Ratones Noqueados , Receptores de Calcitriol/deficienciaRESUMEN
Lipid accumulation in the heart is associated with obesity and diabetes and may play an important role in the pathogenesis of heart failure. The renin-angiotensin system is also thought to contribute to cardiovascular morbidity in obese and diabetic patients. We hypothesized that the presence of lipid within the myocyte might potentiate the cardiomyopathic effects of ANG II in the cardiac diacylglycerol acyl transferase 1 (DGAT1) transgenic mouse model of myocyte steatosis. Treatment with ANG II resulted in a similar increase in blood pressure in both nontransgenic and DGAT1 transgenic mice. However, ANG II in DGAT1 transgenic mice resulted in a marked increase in interstitial fibrosis and a reduction in systolic function compared with nontransgenic littermates. Lipidomic analysis revealed that >20% of lipid species were significantly altered between nontransgenic and DGAT1 transgenic animals, whereas 3% were responsive to ANG II administration. ROS were also increased by ANG II in DGAT1 transgenic hearts. ANG II treatment resulted in increased expression of transforming growth factor (TGF)-ß2 and the type I TGF-ß receptor as well as increased phosphorylation of Smad2 in DGAT1 transgenic hearts. Injection of neutralizing antibodies to TGF-ß resulted in a reduction in fibrosis in DGAT1 transgenic hearts treated with ANG II. These results suggest that myocyte steatosis amplifies the fibrotic effects of ANG II through mechanisms that involve activation of TGF-ß signaling and increased production of ROS.
Asunto(s)
Angiotensina II/farmacología , Cardiomiopatías/metabolismo , Metabolismo de los Lípidos , Miocitos Cardíacos/metabolismo , Animales , Cardiomiopatías/fisiopatología , Células Cultivadas , Diacilglicerol O-Acetiltransferasa/genética , Diacilglicerol O-Acetiltransferasa/metabolismo , Fibrosis/metabolismo , Ventrículos Cardíacos/metabolismo , Ventrículos Cardíacos/patología , Ventrículos Cardíacos/fisiopatología , Ratones , Ratones Endogámicos DBA , Miocitos Cardíacos/efectos de los fármacos , Especies Reactivas de Oxígeno/metabolismo , Receptores de Factores de Crecimiento Transformadores beta/metabolismo , Factor de Crecimiento Transformador beta2/metabolismo , Triglicéridos/metabolismoRESUMEN
Vitamin D deficiency has been associated with cardiovascular dysfunction. We evaluated the role of the vitamin D receptor (VDR) in vascular endothelial function, a marker of cardiovascular health, at baseline and in the presence of angiotensin II, using an endothelial-specific knockout of the murine VDR gene. In the absence of endothelial VDR, acetylcholine-induced aortic relaxation was significantly impaired (maximal relaxation, endothelial-specific VDR knockout=58% versus control=73%; P<0.05). This was accompanied by a reduction in endothelial NO synthase expression and phospho-vasodilator-stimulated phosphoprotein levels in aortae from the endothelial-specific VDR knockout versus control mice. Although blood pressure levels at baseline were comparable at 12 and 24 weeks of age, the endothelial VDR knockout mice demonstrated increased sensitivity to the hypertensive effects of angiotensin II compared with control mice (after 1-week infusion: knockout=155±15 mm Hg versus control=133±7 mm Hg; P<0.01; after 2-week infusion: knockout=164±9 mm Hg versus control=152±13 mm Hg; P<0.05). By the end of 2 weeks, angiotensin II infusion-induced, hypertrophy-sensitive myocardial gene expression was higher in endothelial-specific VDR knockout mice (fold change compared with saline-infused control mice, type-A natriuretic peptide: knockout mice=3.12 versus control=1.7; P<0.05; type-B natriuretic peptide: knockout mice=4.72 versus control=2.68; P<0.05). These results suggest that endothelial VDR plays an important role in endothelial cell function and blood pressure control and imply a potential role for VDR agonists in the management of cardiovascular disease associated with endothelial dysfunction.
Asunto(s)
Endotelio Vascular/fisiopatología , Hipertensión/tratamiento farmacológico , Receptores de Calcitriol/antagonistas & inhibidores , Vasodilatación/efectos de los fármacos , Acetilcolina/farmacología , Angiotensina II/farmacología , Animales , Aorta/metabolismo , Presión Sanguínea/efectos de los fármacos , Western Blotting , ADN/genética , Modelos Animales de Enfermedad , Células Endoteliales/metabolismo , Células Endoteliales/patología , Endotelio Vascular/metabolismo , Endotelio Vascular/patología , Regulación de la Expresión Génica , Humanos , Hipertensión/genética , Hipertensión/fisiopatología , Inmunohistoquímica , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Péptido Natriurético Encefálico/metabolismo , Ratas , Receptores de Calcitriol/biosíntesis , Receptores de Calcitriol/genéticaRESUMEN
Vitamin D receptors (VDR) are found in cells throughout the cardiovascular system. A variety of experimental studies indicate that the liganded VDR may play an important role in controlling cardiac hypertrophy and fibrosis, regulating blood pressure, and suppressing the development of atherosclerosis. Some, but not all, observational studies in humans provide support for these experimental findings, raising the possibility that vitamin D or its analogs might prove useful therapeutically in the prevention or treatment of cardiovascular disease.
Asunto(s)
Enfermedades Cardiovasculares/tratamiento farmacológico , Miocardio/metabolismo , Receptores de Calcitriol/agonistas , Vitamina D/uso terapéutico , Animales , Enfermedades Cardiovasculares/metabolismo , Enfermedades Cardiovasculares/patología , Enfermedades Cardiovasculares/fisiopatología , Humanos , Ligandos , Miocardio/patología , Receptores de Calcitriol/metabolismo , Transducción de Señal/efectos de los fármacos , Vitamina D/metabolismoRESUMEN
In recent years, vitamin D has been received increased attention due to the resurgence of vitamin D deficiency and rickets in developed countries and the identification of extraskeletal effects of vitamin D, suggesting unexpected benefits of vitamin D in health and disease, beyond bone health. The possibility of extraskeletal effects of vitamin D was first noted with the discovery of the vitamin D receptor (VDR) in tissues and cells that are not involved in maintaining mineral homeostasis and bone health, including skin, placenta, pancreas, breast, prostate and colon cancer cells, and activated T cells. However, the biological significance of the expression of the VDR in different tissues is not fully understood, and the role of vitamin D in extraskeletal health has been a matter of debate. This report summarizes recent research on the roles for vitamin D in cancer, immunity and autoimmune diseases, cardiovascular and respiratory health, pregnancy, obesity, erythropoiesis, diabetes, muscle function, and aging.
Asunto(s)
Deficiencia de Vitamina D/fisiopatología , Vitamina D/fisiología , Adulto , Animales , Enfermedades Autoinmunes/etiología , Señalización del Calcio , Enfermedades Cardiovasculares/etiología , Enfermedades Cardiovasculares/fisiopatología , Trastornos del Conocimiento/fisiopatología , Trastornos del Conocimiento/prevención & control , Diabetes Mellitus Tipo 2/fisiopatología , Modelos Animales de Enfermedad , Eritropoyesis/efectos de los fármacos , Eritropoyesis/fisiología , Femenino , Humanos , Sistema Inmunológico/fisiología , Lactante , Lactancia/fisiología , Masculino , Ratones , Necesidades Nutricionales , Obesidad/tratamiento farmacológico , Obesidad/fisiopatología , Especificidad de Órganos , Embarazo/fisiología , Enfermedad Pulmonar Obstructiva Crónica/complicaciones , Enfermedad Pulmonar Obstructiva Crónica/fisiopatología , Ensayos Clínicos Controlados Aleatorios como Asunto , Receptores de Calcitriol/fisiología , Vitamina D/administración & dosificación , Vitamina D/uso terapéutico , Deficiencia de Vitamina D/complicaciones , Deficiencia de Vitamina D/prevención & controlRESUMEN
OBJECTIVE: We describe a young woman with previously undiagnosed thyrotoxicosis who presented with acute liver failure (ALF). METHODS: We present a case report and review the relevant literature. RESULTS: An extensive evaluation excluded possible causes of ALF other than thyrotoxicosis. The management of thyrotoxicosis posed several unique challenges in the setting of ALF, particularly because we did not want to use potentially hepatotoxic thionamides. The patient was treated with prednisone and propranolol and was started on potassium iodide when she was listed for liver transplantation. She underwent an uncomplicated liver transplant and subsequent thyroidectomy and is doing well. CONCLUSION: This well-characterized case describes thyrotoxicosis as a possible cause of ALF after thoroughly excluding other possible causes and illustrates the challenges of simultaneously managing both disorders. To our knowledge, this is the first report of ALF possibly resulting from untreated thyrotoxicosis that was successfully treated with liver transplantation.
Asunto(s)
Fallo Hepático Agudo/diagnóstico , Fallo Hepático Agudo/cirugía , Trasplante de Hígado , Tirotoxicosis/diagnóstico , Tirotoxicosis/cirugía , Adulto , Femenino , Humanos , Fallo Hepático Agudo/tratamiento farmacológico , Yoduro de Potasio/uso terapéutico , Prednisona/uso terapéutico , Propranolol/uso terapéutico , Tirotoxicosis/tratamiento farmacológico , Resultado del TratamientoRESUMEN
Vitamin D and its analogs have been suggested to have palliative effects in the cardiovascular system. We have examined the effects of co-administration of the vitamin D receptor agonist, paricalcitol, on the hypertension, cardiac hypertrophy and interstitial fibrosis produced by chronic angiotensin II (AII) infusion. Administration of AII (800ng/kg/min) over a 14-day period resulted in increased blood pressure, myocyte hypertrophy, activation of the hypertrophic fetal gene program (atrial natriuretic peptide, B-type natriuretic peptide and alpha skeletal actin gene expression), increased expression of the pro-hypertrophic modulatory calcineurin inhibitor protein 1 (MCIP 1), and increased fibrosis with augmented procollagen 1 and 3 gene expression. In each case co-administration of paricalcitol (300ng/kg intraperitoneally every 48h) at least partially reversed the AII-dependent effect. These studies demonstrate that the liganded vitamin D receptor possesses potent anti-hypertrophic activity in this non-renin-dependent model of cardiac hypertrophy. The anti-hypertrophic activity appears to be at least partially intrinsic to the cardiac myocyte and may involve suppression of the MCIP 1 protein. This article is part of a Special Issue entitled 'Vitamin D Workshop'.
Asunto(s)
Hipertrofia Ventricular Izquierda/metabolismo , Hipertrofia Ventricular Izquierda/prevención & control , Miocardio/metabolismo , Receptores de Calcitriol/metabolismo , Angiotensina II/administración & dosificación , Animales , Proteínas de Unión al Calcio , Ergocalciferoles/farmacología , Expresión Génica/efectos de los fármacos , Hipertrofia Ventricular Izquierda/patología , Péptidos y Proteínas de Señalización Intracelular/genética , Ligandos , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Proteínas Musculares/genética , Miocardio/patología , Miocitos Cardíacos/metabolismo , Miocitos Cardíacos/patología , Receptores de Calcitriol/agonistas , Receptores de Calcitriol/deficienciaRESUMEN
C-type natriuretic peptide (CNP/Nppc) is expressed at high levels in the anterior pituitary of rats and mice and activates guanylyl cyclase B receptors (GC-B/Npr2) to regulate hormone secretion. Mutations in NPR2/Npr2 can cause achondroplasia, GH deficiency, and female infertility, yet the normal expression profile within the anterior pituitary remains to be established in humans. The current study examined the expression profile and transcriptional regulation of NPR2 and GC-B protein in normal human fetal pituitaries, normal adult pituitaries, and human pituitary adenomas using RT-PCR and immunohistochemistry. Transcriptional regulation of human NPR2 promoter constructs was characterized in anterior pituitary cell lines of gonadotroph, somatolactotroph, and corticotroph origin. NPR2 was detected in all human fetal and adult pituitary samples regardless of age or sex, as well as in all adenoma samples examined regardless of tumor origin. GC-B immunoreactivity was variable in normal pituitary, gonadotrophinomas, and somatotrophinomas. Maximal transcriptional regulation of the NPR2 promoter mapped to a region within -214âbp upstream of the start site in all anterior pituitary cell lines examined. Electrophoretic mobility shift assays revealed that this region contains Sp1/Sp3 response elements. These data are the first to show NPR2 expression in normal human fetal and adult pituitaries and adenomatous pituitary tissue and suggest a role for these receptors in both pituitary development and oncogenesis, introducing a new target to manipulate these processes in pituitary adenomas.
Asunto(s)
Adenoma/genética , Feto/metabolismo , Péptido Natriurético Tipo-C/fisiología , Hipófisis/metabolismo , Neoplasias Hipofisarias/genética , Receptores del Factor Natriurético Atrial/genética , Adenoma/metabolismo , Adulto , Anciano , Animales , Células Cultivadas , Femenino , Regulación Enzimológica de la Expresión Génica , Regulación Neoplásica de la Expresión Génica , Humanos , Masculino , Ratones , Ratones Endogámicos C57BL , Persona de Mediana Edad , Péptido Natriurético Tipo-C/genética , Péptido Natriurético Tipo-C/metabolismo , Hipófisis/embriología , Hipófisis/patología , Neoplasias Hipofisarias/metabolismo , Embarazo , Ratas , Receptores del Factor Natriurético Atrial/metabolismoRESUMEN
Angiotensin-converting enzyme (ACE) inhibitors ameliorate the progression of renal disease. In combination with vitamin D receptor activators, they provide additional benefits. In the present study, uremic (U) rats were treated as follows: U+vehicle (UC), U+enalapril (UE; 25 mg/l in drinking water), U+paricalcitol (UP; 0.8 µg/kg ip, 3 × wk), or U+enalapril+paricalcitol (UEP). Despite hypertension in UP rats, proteinuria decreased by 32% vs. UC rats. Enalapril alone, or in combination with paricalcitol, further decreased proteinuria (≈70%). Glomerulosclerosis and interstitial infiltration increased in UC rats. Paricalcitol and enalapril inhibited this. The increase in cardiac atrial natriuretic peptide (ANP) seen in UC rats was significantly decreased by paricalcitol. Enalapril produced a more dramatic reduction in ANP. Renal oxidative stress plays a critical role in inflammation and progression of sclerosis. The marked increase in p22(phox), a subunit of NADPH oxidase, and decrease in endothelial nitric oxide synthase were inhibited in all treated groups. Cotreatment with both compounds inhibited the uremia-induced increase in proinflammatory inducible nitric oxide synthase (iNOS) and glutathione peroxidase activity better than either compound alone. Glutathione reductase was also increased in UE and UP rats vs. UC. Kidney 4-hydroxynonenal was significantly increased in the UC group compared with the normal group. Combined treatment with both compounds significantly blunted this increase, P < 0.05, while either compound alone had no effect. Additionally, the expression of Mn-SOD was increased and CuZn-SOD decreased by uremia. This was ameliorated in all treatment groups. Cotreatment with enalapril and paricalcitol had an additive effect in increasing CuZn-SOD expression. In conclusion, like enalapril, paricalcitol alone can improve proteinuria, glomerulosclerosis, and interstitial infiltration and reduce renal oxidative stress. The effects of paricalcitol may be amplified when an ACE inhibitor is added since cotreatment with both compounds seems to have an additive effect on ameliorating uremia-induced changes in iNOS and CuZn-SOD expression, peroxidase activity, and renal histomorphometry.
Asunto(s)
Enalapril/uso terapéutico , Ergocalciferoles/uso terapéutico , Glomerulonefritis/tratamiento farmacológico , Proteinuria/tratamiento farmacológico , Receptores de Calcitriol/efectos de los fármacos , Aldehídos/metabolismo , Inhibidores de la Enzima Convertidora de Angiotensina/farmacología , Animales , Factor Natriurético Atrial/efectos de los fármacos , Femenino , Riñón/efectos de los fármacos , NADPH Oxidasas/metabolismo , Óxido Nítrico Sintasa de Tipo II/metabolismo , Estrés Oxidativo/efectos de los fármacos , Proteinuria/metabolismo , Ratas , Superóxido Dismutasa/metabolismo , Uremia/metabolismoAsunto(s)
Ameloblastoma/tratamiento farmacológico , Antibióticos Antineoplásicos/administración & dosificación , Bleomicina/administración & dosificación , Neoplasias Maxilomandibulares/tratamiento farmacológico , Ameloblastoma/cirugía , Animales , Quimioterapia Adyuvante , Perros , Humanos , Inyecciones Intralesiones , Neoplasias Maxilomandibulares/cirugíaRESUMEN
BACKGROUND: A variety of studies carried out using either human subjects or laboratory animals suggest that vitamin D and its analogues possess important beneficial activity in the cardiovascular system. Using Cre-Lox technology we have selectively deleted the vitamin D receptor (VDR) gene in the cardiac myocyte in an effort to better understand the role of vitamin D in regulating myocyte structure and function. METHODS AND RESULTS: Targeted deletion of the exon 4 coding sequence in the VDR gene resulted in an increase in myocyte size and left ventricular weight/body weight versus controls both at baseline and following a 7-day infusion of isoproterenol. There was no increase in interstitial fibrosis. These knockout mice demonstrated a reduction in end-diastolic and end-systolic volume by echocardiography, activation of the fetal gene program (ie, increased atrial natriuretic peptide and alpha skeletal actin gene expression), and increased expression of modulatory calcineurin inhibitory protein 1 (MCIP1), a direct downstream target of calcineurin/nuclear factor of activated T cell signaling. Treatment of neonatal cardiomyocytes with 1,25-dihydroxyvitamin D partially reduced isoproterenol-induced MCIP1 mRNA and protein levels and MCIP1 gene promoter activity. CONCLUSIONS: Collectively, these studies demonstrate that the vitamin D-VDR signaling system possesses direct, antihypertrophic activity in the heart. This appears to involve, at least in part, suppression of the prohypertrophic calcineurin/NFAT/MCIP1 pathway. These studies identify a potential mechanism to account for the reported beneficial effects of vitamin D in the cardiovascular system.
Asunto(s)
Cardiomegalia/etiología , Cardiomegalia/genética , Eliminación de Gen , Miocitos Cardíacos/metabolismo , Receptores de Calcitriol/deficiencia , Receptores de Calcitriol/genética , Animales , Cardiomegalia/metabolismo , Marcación de Gen , Ratones , Ratones de la Cepa 129 , Ratones Endogámicos C57BL , Ratones Noqueados , Miocitos Cardíacos/patologíaRESUMEN
Lipid accumulation in the heart is associated with obesity and diabetes mellitus and may play an important role in the pathogenesis of heart failure seen in this patient population. Stored triglycerides are synthesized by the enzyme diacylglycerol acyl transferase (DGAT). We hypothesized that forced expression of DGAT1 in the cardiac myocyte would result in increased lipid accumulation and heart dysfunction. A cardiac myocyte-selective DGAT1 transgenic mouse was created and demonstrated increased lipid accumulation in the absence of hyperglycemia, plasma dyslipidemia or differences in body weight. Over time, expression of DGAT1 in the heart resulted in the development of a significant cardiomyopathy. Echocardiography revealed diastolic dysfunction with increased early mitral inflow velocity to late mitral inflow velocity ratio and decreased deceleration time, suggesting a restrictive pattern in the transgenic mice. Moderate systolic dysfunction was also seen at 52 weeks. Histological analysis showed increased cardiac fibrosis and increased expression of procollagen type 1A, matrix metalloproteinase 2, and tissue inhibitor of matrix metalloproteinase 2 in the transgenic mice. Mitochondrial biogenesis was reduced in the transgenic hearts, as was expression of cytochrome c oxidase 1 and cytochrome c. Expression of key transcription factors important in the regulation of mitochondrial biogenesis were reduced. These findings suggest that triglyceride accumulation, in the absence of systemic metabolic derangement, results in cardiac dysfunction and decreased mitochondrial biogenesis.
Asunto(s)
Cardiomiopatías/metabolismo , Diacilglicerol O-Acetiltransferasa/metabolismo , Ácidos Grasos/metabolismo , Miocardio/metabolismo , Animales , Animales Recién Nacidos , Western Blotting , Cardiomiopatías/patología , Cardiomiopatías/fisiopatología , Células Cultivadas , Citocromos c/metabolismo , Diacilglicerol O-Acetiltransferasa/genética , Modelos Animales de Enfermedad , Femenino , Fibrosis , Expresión Génica , Metabolismo de los Lípidos , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Endogámicos DBA , Ratones Transgénicos , Mitocondrias/metabolismo , Miocardio/patología , Miocitos Cardíacos/metabolismo , Miocitos Cardíacos/patología , Ratas , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Factores de Tiempo , Triglicéridos/metabolismoAsunto(s)
Humanos , Enfermedades del Sistema Endocrino/terapia , Endocrinología/educación , Hormonas/clasificación , Medicina Basada en la Evidencia , Sistema Endocrino/anatomía & histología , Sistema Endocrino/fisiología , Glándulas Endocrinas , Hipotálamo , Hipófisis , Hormona de Crecimiento Humana , Hormonas Tiroideas , Neoplasia Endocrina MúltipleRESUMEN
We have explored the mechanism(s) underlying 1,25 dihydroxyvitamin D's (1,25(OH)(2)D) suppression of agonist-induced vascular smooth muscle cell (VSMC) proliferation. Quiescent cultured adult rat VSMC were treated with 1,25(OH)(2)D for 48h and endothelin (ET) or angiotensin II (AII) for the final 24h. We show that VSMC responded to 1,25(OH)(2)D or its less hypercalcemic analogue RO 25-6760 with â¼70% inhibition of ET-dependent (3)H-thymidine incorporation. The inhibition was linked to a comparable reduction in ET-stimulated cyclin-dependent kinase 2 (Cdk2) activity and suppression of an ET-induced Cdk2 activator, cell division cycle 25 homolog A (Cdc25A). Both 1,25(OH)(2)D and RO 25-6760 completely inhibited the ET-dependent increase in Cdc25A mRNA and protein levels, phosphatase and promoter activities. 1,25(OH)(2)D also suppressed AII-induced DNA synthesis, Cdk2 activity and Cdc25A gene transcription. Inhibition of Cdc25A gene expression using a siRNA approach resulted in significant inhibition of ET or AII-dependent Cdk2 activity and (3)H-thymidine incorporation. The Cdc25A siRNA-mediated inhibition of ET or AII-induced Cdk2 activity and DNA synthesis was not additive with that produced by 1,25(OH)(2)D treatment. These data demonstrate that 1,25(OH)(2)D inhibits VSMC proliferation through a Cdc25A-dependent mechanism and suggest that this hormone may prove useful in the management of disorders characterized by aberrant proliferation of VSMC in the vascular wall.
Asunto(s)
Calcitriol/farmacología , Proliferación Celular/efectos de los fármacos , Músculo Liso Vascular/citología , Fosfatasas cdc25/fisiología , Angiotensina II/farmacología , Animales , Células Cultivadas , Colecalciferol/análogos & derivados , Colecalciferol/farmacología , Quinasa 2 Dependiente de la Ciclina/metabolismo , Endotelinas/farmacología , RatasRESUMEN
1,25 dihydroxyvitamin D(3) (1,25 (OH)2 D) and its less hypercalcemic analogues have been shown to inhibit the proliferation of vascular smooth muscle cells (VSMC) in culture. However, the mechanism(s) underlying this suppression is not well understood. Here we have shown that 1,25 (OH)2 D and its analogues (RO-25-6760 and RO-23-7553) inhibit endothelin (ET)-dependent DNA synthesis and cell proliferation in neonatal rat aortic VSMC. While ET stimulation of mitogenic activity requires activation of the MEK/ERK signal transduction cascade, 1,25 (OH)2 D neither affected the ET-dependent activation of ERK nor synergized with the MEK inhibitor PD98059 in reducing DNA synthesis in these cultures, implying that the locus of 1,25 (OH)2 D actions lies between ERK and the cell cycle machinery. 1,25 (OH)2 D suppressed ET-induced activation of cyclin-dependent kinase 2 (Cdk2), a key cell cycle kinase, but had no effect on the expression of this protein. Collectively, the data identify Cdk2 as the target of 1,25 (OH)2 D in the cell cycle machinery and imply a potential role for 1,25 (OH)2 D, or its less hypercalcemic analogues, in the treatment of disorders of VSMC proliferation involving the vascular wall.
Asunto(s)
Proliferación Celular/efectos de los fármacos , Quinasa 2 Dependiente de la Ciclina/antagonistas & inhibidores , Músculo Liso Vascular/citología , Miocitos del Músculo Liso/citología , Miocitos del Músculo Liso/efectos de los fármacos , Transducción de Señal/efectos de los fármacos , Vitamina D/farmacología , Animales , Animales Recién Nacidos , Calcitriol/análogos & derivados , Calcitriol/farmacología , Células Cultivadas , Quinasa 2 Dependiente de la Ciclina/metabolismo , Proteínas Inhibidoras de las Quinasas Dependientes de la Ciclina/metabolismo , Inhibidor p21 de las Quinasas Dependientes de la Ciclina/metabolismo , Quinasas Ciclina-Dependientes/metabolismo , Ciclinas/metabolismo , Quinasas MAP Reguladas por Señal Extracelular/metabolismo , Flavonoides/farmacología , Proteínas Quinasas JNK Activadas por Mitógenos/metabolismo , Quinasas de Proteína Quinasa Activadas por Mitógenos/antagonistas & inhibidores , Quinasas de Proteína Quinasa Activadas por Mitógenos/metabolismo , Miocitos del Músculo Liso/metabolismo , Inhibidores de Proteínas Quinasas/farmacología , Ratas , Receptores de Calcitriol/metabolismo , Transducción de Señal/fisiología , Vitamina D/análogos & derivadosRESUMEN
AIMS: Atrial natriuretic peptide (ANP) is a hormone that has both antihypertrophic and antifibrotic properties in the heart. We hypothesized that myocyte-derived ANP inhibits endothelin (ET) gene expression in fibroblasts. METHODS AND RESULTS: We have investigated the mechanism(s) involved in the antiproliferative effect of ANP on cardiac fibroblasts in a cell culture model. We found that cardiac myocytes inhibited DNA synthesis in co-cultured cardiac fibroblasts as did treatment with the ET-1 antagonist BQ610. The effect of co-culture was reversed by antibody directed against ANP or the ANP receptor antagonist HS-142-1. ANP inhibited the expression of the ET-1 gene and ET-1 gene promoter activity in cultured fibroblasts. The site of the inhibition was localized to a GATA-binding site positioned between -132 and -135 upstream from the transcription start site. GATA4 expression was demonstrated in cardiac fibroblasts, GATA4 bound the ET-1 promoter both in vitro and in vivo, and siRNA-mediated knockdown of GATA4 inhibited ET-1 expression. ET-1 treatment resulted in increased levels of phospho-serine(105) GATA4 in cardiac fibroblasts and this induction was partially suppressed by co-treatment with ANP. CONCLUSION: Collectively, these findings suggest that locally produced ET-1 serves as an autocrine stimulator of fibroblast proliferation, that ANP produced in neighbouring myocytes serves as a paracrine inhibitor of this proliferation, and that the latter effect operates through a reduction in GATA4 phosphorylation and coincident reduction in GATA4-dependent transcriptional activity.
Asunto(s)
Factor Natriurético Atrial/metabolismo , Proliferación Celular , Endotelina-1/metabolismo , Fibroblastos/metabolismo , Factor de Transcripción GATA4/metabolismo , Miocitos Cardíacos/metabolismo , Animales , Animales Recién Nacidos , Comunicación Autocrina , Sitios de Unión , Proliferación Celular/efectos de los fármacos , Células Cultivadas , Técnicas de Cocultivo , Replicación del ADN , Relación Dosis-Respuesta a Droga , Regulación hacia Abajo , Endotelina-1/antagonistas & inhibidores , Endotelina-1/genética , Quinasas MAP Reguladas por Señal Extracelular/metabolismo , Fibroblastos/efectos de los fármacos , Factor de Transcripción GATA4/genética , Ventrículos Cardíacos/citología , Ventrículos Cardíacos/metabolismo , Oligopéptidos/farmacología , Comunicación Paracrina , Fosforilación , Polisacáridos/farmacología , Regiones Promotoras Genéticas , Interferencia de ARN , Ratas , Ratas Sprague-Dawley , Receptores del Factor Natriurético Atrial/antagonistas & inhibidores , Receptores del Factor Natriurético Atrial/metabolismo , Serina , Transducción de Señal , Activación Transcripcional , TransfecciónRESUMEN
In various mammalian species, including humans, water restriction leads to an acute increase in urinary sodium excretion. This process, known as dehydration natriuresis, helps prevent further accentuation of hypernatremia and the accompanying rise in extracellular tonicity. Serum- and glucocorticoid-inducible kinase (Sgk1), which is expressed in the renal medulla, is regulated by extracellular tonicity. However, the mechanism of its regulation and the physiological role of hypertonicity-induced SGK1 gene expression remain unclear. Here, we identified a tonicity-responsive enhancer (TonE) upstream of the rat Sgk1 transcriptional start site. The transcription factor NFAT5 associated with TonE in a tonicity-dependent fashion in cultured rat renal medullary cells, and selective blockade of NFAT5 activity resulted in suppression of the osmotic induction of the Sgk1 promoter. In vivo, water restriction of rats or mice led to increased urine osmolality, increased Sgk1 expression, increased expression of the type A natriuretic peptide receptor (NPR-A), and dehydration natriuresis. In cultured rat renal medullary cells, siRNA-mediated Sgk1 knockdown blocked the osmotic induction of natriuretic peptide receptor 1 (Npr1) gene expression. Furthermore, Npr1-/- mice were resistant to dehydration natriuresis, which suggests that Sgk1-dependent activation of the NPR-A pathway may contribute to this response. Collectively, these findings define a specific mechanistic pathway for the osmotic regulation of Sgk1 gene expression and suggest that Sgk1 may play an important role in promoting the physiological response of the kidney to elevations in extracellular tonicity.
Asunto(s)
Deshidratación/metabolismo , Proteínas Inmediatas-Precoces/metabolismo , Natriuresis , Proteínas Serina-Treonina Quinasas/metabolismo , Animales , Deshidratación/genética , Regulación de la Expresión Génica , Proteínas Inmediatas-Precoces/genética , Soluciones Isotónicas , Masculino , Ratones , Ratones Noqueados , Mutación/genética , Factores de Transcripción NFATC/genética , Factores de Transcripción NFATC/metabolismo , Regiones Promotoras Genéticas , Unión Proteica , Proteínas Serina-Treonina Quinasas/genética , ARN Interferente Pequeño/genética , Ratas , Receptores del Factor Natriurético Atrial/deficiencia , Receptores del Factor Natriurético Atrial/genética , Receptores del Factor Natriurético Atrial/metabolismoRESUMEN
Increased B-type natriuretic peptide (BNP) gene expression is regarded as one of the hallmarks of cardiac myocyte hypertrophy. Here we demonstrate that both basal- and endothelin-1-dependent stimulation of human (h) BNP gene transcription requires the presence of an intact Yin Yang 1 (YY1) binding site positioned at -62 bp relative to the transcription start site. Mutation of this site reduced both basal and stimulated hBNP promoter activity. This site was shown to bind YY1 both in vitro and within the context of the intact cell. The latter interaction increased after endothelin-1 treatment. Exposure to endothelin-1 also resulted in increased nuclear localization of YY1 and a reduction in acetylation of the YY1 protein. Overexpression of wild-type YY1 increased both basal and endothelin-stimulated hBNP promoter activity, whereas a carboxy-terminal deletion mutant of YY1 was devoid of activity. Treatment with the histone deacetylase inhibitor trichostatin A resulted in decreased hBNP reporter activity. YY1 was shown to associate with histone deacetylase 2, and histone deacetylase 2 was shown to associate directly with the hBNP promoter in the intact cell. Collectively these findings demonstrate that YY1 plays an important role in regulating the transcriptional activity of the hBNP gene promoter. These data suggest a model in which YY1 activates hBNP transcription through interaction with histone deacetylase 2.
Asunto(s)
Endotelina-1/farmacología , Regulación de la Expresión Génica/efectos de los fármacos , Histona Desacetilasas/metabolismo , Miocitos Cardíacos/metabolismo , Péptido Natriurético Encefálico/genética , Péptido Natriurético Encefálico/metabolismo , Proteínas Represoras/metabolismo , Factor de Transcripción YY1/metabolismo , Animales , Núcleo Celular/metabolismo , Células Cultivadas , Inhibidores Enzimáticos/farmacología , Histona Desacetilasa 2 , Inhibidores de Histona Desacetilasas , Humanos , Ácidos Hidroxámicos/farmacología , Miocitos Cardíacos/citología , Miocitos Cardíacos/efectos de los fármacos , Regiones Promotoras Genéticas/genética , Ratas , Ratas Sprague-Dawley , Proteínas Represoras/antagonistas & inhibidores , TransfecciónRESUMEN
The liganded vitamin D receptor (VDR) is thought to play an important role in controlling cardiac function. Specifically, this system has been implicated as playing an antihypertrophic role in the heart. Despite this, studies of VDR in the heart have been limited in number and scope. In the present study, we used a combination of real-time polymerase chain reaction, Western blot analysis, immunofluorescence, and transient transfection analysis to document the presence of functional VDR in both the myocytes and fibroblasts of the heart, as well as in the intact ventricular myocardium. We also demonstrated the presence of 1-alpha-hydroxylase and 24-hydroxylase in the heart, 2 enzymes involved in the synthesis and metabolism of 1,25 dihydroxyvitamin D. VDR is shown to interact directly with the human B-type natriuretic peptide gene promoter, a surrogate marker of the transcriptional response to hypertrophy. Of note, induction of myocyte hypertrophy either in vitro or in vivo leads to an increase in VDR mRNA and protein levels. Collectively, these findings suggest that the key components required for a functional 1,25 dihydroxyvitamin D-dependent signaling system are present in the heart and that this putatively antihypertrophic system is amplified in the setting of cardiac hypertrophy.