NF-kappaB p65 S-nitrosylation inhibits TSH-induced Na+/I- Symporter expression

NICOLA JUAN PABLO, PEYRET VICTORIA, NAZAR MAGALÍ, ROMERO JORGE MIGUEL, LUCERO ARIEL MAXIMILIANO, MONTESINOS MARÍA DEL MAR, BOCCO,JOSÉ LUIS, PELLIZAS CLAUDIA GABRIELA, MASINI - REPISO ANA MARÍA

Orlando, Florida

Congreso; 15th International thyroid Congress (15th ITC); 2015

American Thyroid Association

Introduction: Nitric oxide (NO) is a ubiquitous signaling molecule involved in a wide variety of cellular physiological processes. In thyroid cells, NO-synthase III-endogenously produced NO reduces thyrotropin (TSH)-stimulated thyroid specific gene expression, suggesting a potential autocrine role of NO in modulating thyroid function. Further studies indicate that NO induces thyroid dedifferentiation, since NO donors repress TSH-stimulated I uptake. Here, we investigated the molecular mechanism underlying the NO-inhibited Na /I Symporter (NIS)-mediated I uptake in thyroid cells.Methods / Case Presentation: FRTL-5 cells, a line of highly differentiated rat thyroid-derived cells, were incubated with different NO donors (sodium nitroprusside, S-nitrosoglutathione, Spermine NONOate). NIS function was measured using I transport assays, and NIS expression was evaluated through western blot, RT/qPCR, and gene reporter assays. NIS post-transcriptional modifications were evaluated in FRTL-5 cells stably expressing N-terminal HA-tagged NIS.Results / Discussion: NO donors reduced I uptake in a concentration-dependent manner, which correlated with decreased NIS protein expression. NO-reduced I uptake resulted from transcriptional repression of NIS gene rather than post-transcriptional modifications impairing functional NISexpression at the plasma membrane. We observed that NO donors repress TSH-induced NIS gene expression by reducing the NF-κB subunitp65-dependent transcriptional activity rather than affecting Pax8 expression or transcriptional activity. NO-promoted Cys-38 p65 S-nitrosylation reduces p65-mediated transactivation of the NIS promoter in response to TSH stimulation.Conclusions: We demonstrated that exogenous NO-induced p65S-nitrosylation repressed TSH-stimulated NIS gene transcription, thusleading to a subsequent reduction of NIS-mediated I uptake in rat thyrocytes.These findings support the participation of NO as an inhibitory signalmolecule to counterbalance TSH-stimulated NF-κB activation, thus modulating TSH-induced thyroid specific gene expression.