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* Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas, Valladolid, Spain; and
Facultad de Medicina, Universidad de Valladolid, Valladolid, Spain
Stimulation of human monocyte-derived dendritic cells with the yeast extract zymosan is characterized by a predominant production of IL-10 and a strong induction of cyclooxygenase-2, but the molecular mechanisms underlying this response are only partially understood. To address this issue, the activation of transcription factors that may bind to the il10 proximal promoter was studied. Binding activity to Sp1, Sp3, NF-Y, and cAMP response element (CRE) sites was detected in the nuclear extracts of dendritic cells; however these binding activities were not influenced by zymosan. No binding activity to Stat1, Stat3, and c/EBP sites was detected. Notably, zymosan activated 
B-binding activity, but inhibition of NF-B was associated with enhanced IL-10 production. In sharp contrast, treatments acting on CREB (CRE binding protein), including 8-Br-cAMP, PGE2, and inhibitors of PKA, COX, and glycogen-synthase kinase-3β showed a direct correlation between CREB activation and IL-10 production. Zymosan induced binding of both P-CREB and CREB-binding protein (CBP) to the il10 promoter as judged from chromatin immunoprecipitation assays, whereas negative results were obtained with Ab reactive to Sp1, Sp3, c-Maf, and NF-Y. Zymosan also induced nuclear translocation of the CREB coactivator transducer of regulated CREB activity 2 (TORC2) and interaction of TORC2 with P-CREB coincidental with the association of CREB to the il10 promoter. Altogether, our data show that zymosan induces il10 transcription by a CRE-dependent mechanism that involves autocrine secretion of PGE2 and a network of interactions of PKA, MAP/ERK, glycogen-synthase kinase-3β, and calcineurin, which regulate CREB transcriptional activity by binding the coactivators CBP and TORC2 and inhibiting CBP interaction with other transcription factors.
The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked advertisement in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
1 This work was supported by grants from Plan Nacional de Salud y Farmacia (Grant SAF2007-60446), Fundación Ramón Areces, Junta de Castilla y León (Grant CSI05C05), and Red Temática de Investigación Cardiovascular. N.F. is under contract within the Ramón y Cajal Program (Ministerio de Ciencia e Innovación of Spain and Fondo Social Europeo).
2 Address correspondence and reprint request to Dr. M. Sánchez Crespo, Instituto de Biología y Genética Molecular, C/Sanz y Forés s/n, 47003-Valladolid, Spain. E-mail address: mscres{at}ibgm.uva.es
3 Abbreviations used in this paper: PRR, pattern recognition receptor; PAMP, pathogen-associated molecular pattern; DC, dendritic cell; DC-SIGN, DC-specific ICAM-3 grabbing nonintegrin; CREB, CRE binding protein; COX, cyclooxygenase; GSK, glycogen synthase kinase; ChIP, chromatin immunoprecipitation; PKA, protein kinase A; MSK, mitogen and stress kinase; CRE, cAMP response element; CBP, CREB-binding protein; Pbx1b, pre-B cell leukemia transcription factor-1b; TBP, TATA box binding protein; TORC2, transducer of regulated CREB activity 2.
4 The online version of this article contains supplemental material.
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