Atrial natriuretic factor and C-type natriuretic peptide induce retraction of human thyrocytes in monolayer culture via guanylyl cyclase receptors

• Published in: Journal of endocrinology Vol. 173; no. 1; pp. 169 - 176
• Main Authors: Sellitti, DF, Lagranha, C, Perrella, G, Curcio, F, Doi, SQ
• Format: Journal Article
• Language: English
• Published: Colchester BioScientifica 01.04.2002; Portland Press
• Subjects: 8-Bromo Cyclic Adenosine Monophosphate - pharmacology; Alkaloids - pharmacology; Analysis of Variance; Animals; Atrial Natriuretic Factor - pharmacology; Biological and medical sciences; Carbazoles; Cell Count; Cell Division - drug effects; Cell Line; Cyclic GMP - metabolism; Cyclic GMP-Dependent Protein Kinases - antagonists & inhibitors; Enzyme Inhibitors - pharmacology; Guanylate Cyclase - metabolism; Humans; Indoles; Microscopy, Phase-Contrast; Natriuretic Peptide, C-Type - pharmacology; Receptors, Atrial Natriuretic Factor - metabolism; Signal Transduction - physiology; Thyroid Gland - drug effects; Thyroid Gland - metabolism
• ISSN: 0022-0795; 1479-6805
• DOI: 10.1677/joe.0.1730169

The natriuretic peptides signal through three receptor subtypes, of which two (NPR-A and NPR-B) are membrane-bound guanylyl cyclases for which the principal ligands are respectively atrial natriuretic factor (ANF) and C-type natriuretic peptide (CNP). In the human thyroid cell, a third receptor, NPR-C, has been implicated in the regulation of thyroglobulin, but functional roles for NPR-A and NPR-B have not yet been defined. In the present study we used RT-PCR to identify transcripts of all three receptor subtypes, both in human thyroid and in HTU-5 cells, a long-term culture of thyroid-derived cells. Both ANF and CNP induced a twofold increase in intracellular cGMP content in HTU-5 cells. Morphologic changes (a significant increase in cells of the retracted phenotype) were observed in ANF- and CNP-treated cells within 3 and 5 h of treatment respectively. Significant increases in retracted cell number were induced by ANF and CNP, but not the NPR-C-specific ring-deleted ANF analog, C-ANF(4-23), during a 15-day treatment. All three natriuretic peptides, however, induced a small (15-20%) but significant (P<0 small middle dot001) increase in DNA content per well. The stable analog of cGMP, 8-bromo-cGMP (8-BrcGMP; 1 mM), also increased the number of retracted HTU-5 cells, and was equipotent with the cAMP analog, 8-BrcAMP, in this effect. The cGMP-dependent protein kinase inhibitor, KT5823, however, had no significant effect on the ANF-induced increase in numbers of retracted cells. These results suggest that the actions of NPR-A and NPR-B, functional receptors in the human thyroid cell, may in part be mediated by cGMP-induced alterations in the cytoskeleton.