C-type natriuretic peptide (CNP) increases [125I]ANF binding to FRTL-5 rat thyroid cells by increasing ANF receptor affinity.
To examine a possible role for C-type natriuretic peptide (CNP) in the thyroid, we studied the ability of this peptide to compete with atrial natriuretic factor (ANF) binding to FRTL-5 rat thyroid cells. Rather than competing for ANF binding, CNP significantly elevated [125I]ANF binding above control at both 23 degrees and 2 degrees C. The increase in ANF binding was due largely to a threefold increase in receptor affinity in the presence of CNP (control, Kd = 8.7 nM; 1 microM CNP, Kd = 3.1 nM). Despite the failure to compete for ANF binding, CNP was almost as effective as ANF at inducing cGMP production in FRTL-5 cells. Competition binding studies using [125I]CNP indicated the presence of a relatively low-affinity site for CNP (Kd = 77 nM) that bound ANF with equal affinity. These results show for the first time that ANF receptor binding can be positively regulated by the related natriuretic peptide, CNP.
Sellitti
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Department of Medicine, Uniformed Services University of the Health Sciences, Bethesda, MD 20814-4799.
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D000818:Animals; D009320:Atrial Natriuretic Factor / Q000378:metabolism*; D001667:Binding, Competitive; D002460:Cell Line; D006152:Cyclic GMP / Q000096:biosynthesis; D007700:Kinetics; D020098:Natriuretic Peptide, C-Type; D011506:Proteins / Q000494:pharmacology*; D051381:Rats; D017461:Receptors, Atrial Natriuretic Factor / Q000187:drug effects* / Q000378:metabolism*; D013961:Thyroid Gland / Q000378:metabolism*
D011506:Proteins; D020098:Natriuretic Peptide, C-Type; D009320:Atrial Natriuretic Factor; D017461:Receptors, Atrial Natriuretic Factor; D006152:Cyclic GMP