T3 stimulates dendritic cell function through a PI3K-independent AKT pathway. Crucial role of TRƒÒ1, a new NFkB target gene

MASCANFRONI ID; MONTESINOS MM; SUSPERREGUY S; ALAMINO VA; NICOLA JP; MASINI-REPISO AM; RABINOVICH GA; PELLIZAS CG

Gramado, Brasil

Congreso; XIII Latin American Thyroid Congress; 2009

Latin American Thyroid Society

We demonstrated that mice dendritic cells (DC), the main antigen presenting cells, express TRb1 with a preferential cytoplasmic localization. Moreover, physiological levels of T3 stimulated DC maturation, strengthened their T cell allostimulatory capacity and directed a T1-type cytokine response, involving cytoplasmic-nuclear shuttling of NF-kB. In this study we aimed at disclosing the signaling pathway involved in T3 action on DC and the role of TRb1 in these effects. In turn we evaluated T3 effect on TRb1 expression in DC and tested TRb1 gene as a putative target of NF-kB. Bone marrow derived DC were treated with T3 (5nM) for 5 min to 18 h. Western blot of Akt/pAkt with or without PI3K inhibitors, co-immunoprecipitation, immunofluorescence and confocal microscopies revealed for the first time the involvement of the Akt pathway independently of PI3K in the recorded T3-induced effects. In turn, experiments conducted with siRNA-TRb-transfected DC (TRb expression abolished) prevented T3-induced DC maturation and function as well as Akt activation and IkBe degradation, demonstrating a crucial role of TRb1 in T3 effects at DC level. In turn, T3 increased TRb1 expression in DC by a mechanism suppressed by NF-kB inhibitors. Chromatin immunoprecipitation (ChIP) analysis revealed a new functional NF-kB consensus site in the promoter region of TRb1 gene. Our findings disclosed the molecular pathway involved in T3 effects on DC, through a cytoplasmic signaling not previously described for T3 action and dependent on TRb1; described TRb1 as a NF-kB target gene and also provided tools to manipulate the immunogenic potential of DC.