Adjunctive Input to the Nuclear Thyroid Hormone Receptor from the Cell Surface Receptor for the Hormone

At thyroid hormone response elements on specific genes, complexes of nuclear thyroid hormone receptors (TRs) and 3,5,3-triiodo-L-thyronine (T-3), coactivator or corepressor nucleoproteins, and histone acetylases or deacetylases mediate genomic effects of the hormone. Nongenomic effects of the hormone are those whose initiation does not primarily depend upon formation of the TR-T-3 complex. Among the nongenomic effects of thyroid hormone are a set of actions initiated at a cell surface receptor on integrin v3 that are relevant to a) intracellular trafficking of proteins, including TR1, b) serine phosphorylation and acetylation of this nuclear receptor, c) assembly within the nucleus of complexes of coactivators and corepressor, and d) transcription of specific genes, including that for TR1. These actions initiated at v3 are reviewed here and appear to be adjunctive to the genomic actions of the TR-T-3 complex.