Atrial natriuretic factor and C-type natriuretic peptide induce retraction of human thyrocytes in monolayer culture via guanylyl cyclase receptors.
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.
Sellitti
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Department of Medicine, Divisions of Endocrinology and Nephrology, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road A3060, Bethesda, MD 20814-4799, USA.
Lagranha
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C
Perrella
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Curcio
F
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Doi
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D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000494:pharmacology; D000470:Alkaloids / Q000494:pharmacology; D000704:Analysis of Variance; D000818:Animals; D009320:Atrial Natriuretic Factor / Q000494:pharmacology*; D002227:Carbazoles; D002452:Cell Count; D002455:Cell Division / Q000187:drug effects; D002460:Cell Line; D006152:Cyclic GMP / Q000378:metabolism; D017869:Cyclic GMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006162:Guanylate Cyclase / Q000378:metabolism; D006801:Humans; D007211:Indoles; D008858:Microscopy, Phase-Contrast; D020098:Natriuretic Peptide, C-Type / Q000494:pharmacology*; D017461:Receptors, Atrial Natriuretic Factor / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology*; D013961:Thyroid Gland / Q000187:drug effects* / Q000378:metabolism; D000099242:Atrial Natriuretic Factor Receptor B
D015124:8-Bromo Cyclic Adenosine Monophosphate; D000470:Alkaloids; D009320:Atrial Natriuretic Factor; D002227:Carbazoles; D006152:Cyclic GMP; D017869:Cyclic GMP-Dependent Protein Kinases; D004791:Enzyme Inhibitors; D006162:Guanylate Cyclase; D007211:Indoles; D020098:Natriuretic Peptide, C-Type; D017461:Receptors, Atrial Natriuretic Factor; D000099242:Atrial Natriuretic Factor Receptor B; C472955:NPPA protein, human; C073601:KT 5823; C091715:atrial natriuretic factor receptor A