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.
Department of Medicine, Uniformed Services University of the Health Sciences, Bethesda, MD 20814-4799.
D F
DF
Sellitti
S Q
SQ
Doi
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