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

NICOLA JP; PEYRET V; NAZAR, M; ROMERO JM; LUCERO AM; MONTESINOS, MM; PELLIZAS CG; MASINI-REPISO AM

Orlando

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

American Thyroid Association

Introduction: Nitric oxide (NO) is a ubiquitous signaling molecule involved ina 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 autocrinerole of NO in modulating thyroid function. Further studies indicate that NOinduces thyroid dedifferentiation, since NO donors repress TSH-stimulated Iuptake. Here, we investigated the molecular mechanism underlying the NO-inhibitedNa /I Symporter (NIS)-mediated I uptake in thyroid cells.Methods / Case Presentation: FRTL-5 cells, a line of highly differentiatedrat thyroid-derived cells, were incubated with different NO donors (sodiumnitroprusside, S-nitrosoglutathione, Spermine NONOate). NIS function wasmeasured using I transport assays, and NIS expression was evaluatedthrough western blot, RT/qPCR, and gene reporter assays. NISpost-transcriptional modifications were evaluated in FRTL-5 cells stablyexpressing N-terminal HA-tagged NIS.Results / Discussion: NO donors reduced I uptake in a concentrationdependentmanner, which correlated with decreased NIS protein expression.NO-reduced I uptake resulted from transcriptional repression of NIS generather than post-transcriptional modifications impairing functional NISexpression at the plasma membrane. We observed that NO donors repressTSH-induced NIS gene expression by reducing the NF-κB subunitp65-dependent transcriptional activity rather than affecting Pax8 expressionor transcriptional activity. NO-promoted Cys-38 p65 S-nitrosylation reducesp65-mediated transactivation of the NIS promoter in response to TSHstimulation.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, thusmodulating TSH-induced thyroid specific gene expression.