RESUMEN
A 24-h treatment with the cytokine tumor necrosis factor-alpha (TNF-alpha) suppresses transcription of E-box-driven clock genes (D-site albumin promoter binding protein, Dbp; Tyrotroph embryonic factor, Tef ; Hepatic leukemia factor, Hlf; Period homolog to Drosophila 1/2/3, Per1, Per2, and Per3) by yet unknown molecular mechanisms. The attenuation of clock genes has been suggested as a putative cause for the development of sickness behavior syndrome in infectious and autoimmune diseases. Here, the authors studied the effect of TNF-alpha at early time points (<3 h) on intracellular signaling events and clock gene expression in fibroblasts. Interaction of TNF-alpha with TNFR1 (Tnfrsf1a , CD120a, p55), but not TNFR2 (Tnfrsf1b, CD120b , p75), leads to fast downregulation of gene expression of Dbp and upregulation of negative regulators of the molecular clock, Per1 and Per2, Cryptochrome-1 (Cry1), and Differentiated embryo chondrocytes-1 (Dec1). Since the decrease of Dbp is also observed in cells deficient for Per1/Per2, Cry1/Cry2 , or Dec1, these genes are unlikely to be responsible for inhibition of Dbp. The early effect of TNF-alpha on the clock gene Per1 is dependent on p38, mitogen-activated protein kinase (MAPK), and/or calcium signaling, whereas the effect on Dbp is independent of p38 MAPK, but also involves calcium signaling. Both genes remain unaffected by the NF-kappaB and AP-1 pathway. Taken collectively these data show p38 MAPK- and calcium-dependent TNFR1-mediated transient increase of the negative regulator Per1 and an independent decrease of Dbp.
Asunto(s)
Relojes Biológicos/genética , Calcio/metabolismo , Sistema de Señalización de MAP Quinasas/efectos de los fármacos , Factor de Necrosis Tumoral alfa/farmacología , Proteínas Quinasas p38 Activadas por Mitógenos/metabolismo , Animales , Western Blotting , Caspasas/metabolismo , Línea Celular , Ensamble y Desensamble de Cromatina/efectos de los fármacos , Inmunoprecipitación de Cromatina , Criptocromos , Proteínas de Unión al ADN/genética , Proteínas de Unión al ADN/metabolismo , Flavoproteínas/genética , Flavoproteínas/metabolismo , Expresión Génica/efectos de los fármacos , Humanos , Péptidos y Proteínas de Señalización Intracelular/genética , Péptidos y Proteínas de Señalización Intracelular/metabolismo , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , FN-kappa B/metabolismo , Células 3T3 NIH , Proteínas Circadianas Period , Receptores Tipo I de Factores de Necrosis Tumoral/genética , Receptores Tipo I de Factores de Necrosis Tumoral/metabolismo , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Factores de Tiempo , Factores de Transcripción/genética , Factores de Transcripción/metabolismoRESUMEN
Disturbances of sleep-wake rhythms are an important problem in Alzheimer's disease (AD). Circadian rhythms are regulated by clock genes. Transforming growth factor-beta (TGF-ß) is overexpressed in neurons in AD and is the only cytokine that is increased in cerebrospinal fluid (CSF). Our data show that TGF-ß2 inhibits the expression of the clock genes Period (Per)1, Per2, and Rev-erbα, and of the clock-controlled genes D-site albumin promoter binding protein (Dbp) and thyrotroph embryonic factor (Tef). However, our results showed that TGF-ß2 did not alter the expression of brain and muscle Arnt-like protein-1 (Bmal1). The concentrations of TGF-ß2 in the CSF of 2 of 16 AD patients and of 1 of 7 patients with mild cognitive impairment were in the dose range required to suppress the expression of clock genes. TGF-ß2-induced dysregulation of clock genes may alter neuronal pathways, which may be causally related to abnormal sleep-wake rhythms in AD patients.
Asunto(s)
Enfermedad de Alzheimer/fisiopatología , Ritmo Circadiano/genética , Regulación de la Expresión Génica , Factor de Crecimiento Transformador beta2/metabolismo , Anciano , Anciano de 80 o más Años , Enfermedad de Alzheimer/líquido cefalorraquídeo , Animales , Factores de Transcripción con Cremalleras de Leucina de Carácter Básico/antagonistas & inhibidores , Factores de Transcripción con Cremalleras de Leucina de Carácter Básico/genética , Proteínas CLOCK/antagonistas & inhibidores , Proteínas CLOCK/genética , Disfunción Cognitiva/metabolismo , Proteínas de Unión al ADN/antagonistas & inhibidores , Proteínas de Unión al ADN/genética , Femenino , Humanos , Masculino , Ratones , Persona de Mediana Edad , Neuronas/metabolismo , Neuronas/patología , Miembro 1 del Grupo D de la Subfamilia 1 de Receptores Nucleares/antagonistas & inhibidores , Miembro 1 del Grupo D de la Subfamilia 1 de Receptores Nucleares/genética , Proteínas Circadianas Period/antagonistas & inhibidores , Proteínas Circadianas Period/genética , Trastornos del Sueño del Ritmo Circadiano/genética , Trastornos del Sueño del Ritmo Circadiano/fisiopatología , Factores de Transcripción/antagonistas & inhibidores , Factores de Transcripción/genética , Factor de Crecimiento Transformador beta2/líquido cefalorraquídeoRESUMEN
Production of TNF-alpha and IL-1 in infectious and autoimmune diseases is associated with fever, fatigue, and sleep disturbances, which are collectively referred to as sickness behavior syndrome. In mice TNF-alpha and IL-1 increase nonrapid eye movement sleep. Because clock genes regulate the circadian rhythm and thereby locomotor activity and may alter sleep architecture we assessed the influence of TNF-alpha on the circadian timing system. TNF-alpha is shown here to suppress the expression of the PAR bZip clock-controlled genes Dbp, Tef, and Hlf and of the period genes Per1, Per2, and Per3 in fibroblasts in vitro and in vivo in the liver of mice infused with the cytokine. The effect of TNF-alpha on clock genes is shared by IL-1beta, but not by IFN-alpha, and IL-6. Furthermore, TNF-alpha interferes with the expression of Dbp in the suprachiasmatic nucleus and causes prolonged rest periods in the dark when mice show spontaneous locomotor activity. Using clock reporter genes TNF-alpha is found here to inhibit CLOCK-BMAL1-induced activation of E-box regulatory elements-dependent clock gene promoters. We suggest that the increase of TNF-alpha and IL-1beta, as seen in infectious and autoimmune diseases, impairs clock gene functions and causes fatigue.