Searchable abstracts of presentations at key conferences in endocrinology
Endocrine Abstracts (2006) 11 P847

ECE2006 Poster Presentations Thyroid (174 abstracts)

Inhibin B/inhibin binding protein complex is differentially expressed in normal and nodular human thyroid tissue

M Della Guardia , A Franchi , S Nardo , MG Santaguida , R Sibilla & M Centanni


University of Rome La Sapienza, Rome, Italy.


Inhibins A and B, peptides belonging to TGF-ß superfamily, have an ubiquitous antagonist action on activin signalling. In thyroid gland, TGF-ß1 and activin mainly exert an inhibitory action on growth and function. In human thyroid, beside the presence of activin β subunits and its transductional elements (ActRI/II, SMAD), there is no evidence for α subunit expression, an essential component for inhibin A/B gathering (α-ßA/α-ßB), nor for its transductional cascade. The identification of mRNA expression for inhibin α subunit and inhibins transductional elements in normal and nodular human thyroid tissue was the aim of this study. We therefore analyzed by competitive RT-PCR 10 samples from goitrous thyroid, 3 of whom from hyperfunctioning nodules, and 3 normal samples as control. Beside the expected mRNA expression for ß subunits we detected for the first time thyroidal expression of α subunit mRNA both in normal and nodular samples, although with a differential pattern. Interestingly, ßB subunit was constantly overexpressed in goitrous tissue, while α subunit levels were increased in hyperfunctioning nodules. We next evaluated the presence of mRNA for ancillary proteins (coreceptor ß-glycan [ßgly], Inhibin Binding Protein [IBP] and Follistatin [FS]) that agonize inhibin binding to ActRII, interfering with activin signalling. ßgly and FS were regularly expressed in all samples, suggesting that human thyroid could be a high affinity target for inhibin. On the contrary, IBP was only expressed in nodular tissue. Since activin signal may be overridden by a specific interaction between inhibin B and IBP, their simultaneous presence suggest a role for this complex in goitrogenesis. These preliminary results show that human thyroid may be a source and a target for inhibin. Also, we suggest that inhibin B/IBP complex may play an autocrine role in the control of thyroid growth.

Volume 11

8th European Congress of Endocrinology incorporating the British Endocrine Societies

European Society of Endocrinology 
British Endocrine Societies 

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