NUCLEAR FACTOR KAPPA B-DEPENDENT THYROID HORMONE RECEPTOR B1- EXPRESSION CONTROLS DENDRITIC CELL FUNCTION VIA AKT SIGNALING

IVAN D. MASCANFRONI; MARIA D. MONTESINOS; VANINA ALAMINO; SEBASTIAN SUSPERREGUY; JUAN NICOLA; JUAN M. ILARREGUI; ANA M. MASINI-REPISO; GABRIEL A. RABINOVICH; CLAUDIA G. PELLIZAS

JOURNAL OF BIOLOGICAL CHEMISTRY

ASBMB

Lugar: BALTIMORE, MD ; Año: 2010 vol. 285 p. 9569 - 9582

0021-9258

In spite of considerable progress in our understanding of the interplay between immune and endocrine systems, the role of thyroid hormones and their receptors in the control of adaptive immunity is still uncertain. Here we investigated the role of thyroid hormone receptor (TR)β1 signaling in modulating dendritic cell (DC) physiology and the intracellular mechanisms underlying these immunoregulatory effects. Exposure of DCs to triiodothyronine (T3) resulted in rapid and sustained increase in Akt phosphorylation independently of PI3K activation, which was essential for supporting T3-induced DC maturation and IL-12 production. This effect was dependent on intact TRβ1 signaling as siRNA-mediated silencing of TRβ1 expression prevented T3-induced DC maturation and IL-12 secretion as well as Akt activation and IκB-ε degradation. In turn, T3 up-regulated TRβ1 expression through mechanisms involving NF-κB, suggesting an autocrine regulatory loop to control hormone-dependent TRβ1 signaling. These findings were confirmed by chromatin immunoprecipitation analysis which disclosed a new functional NF-κB consensus site in the promoter region of the TRB1 gene. Thus, a T3-induced NF-κB-dependent mechanism controls TRβ1 expression, which in turn signals DCs to promote maturation and function via an Akt-dependent, but PI3K independent pathway. These results underscore a novel unrecognized target that regulates DC maturation and function with critical implications in immunopathology at the cross-roads of immune-endocrine circuits.