Novel Bifunctional Natriuretic Peptides as Potential Therapeutics

Abstract

Synthetic atrial natriuretic peptide (carperitide) and B-type natriuretic peptide (BNP; nesiritide) are used to treat congestive heart failure. However, despite beneficial cardiac unloading properties, reductions in renal perfusion pressures limit their clinical effectiveness. Recently, CD-NP, a chimeric peptide composed of C-type natriuretic peptide (CNP) fused to the C-terminal tail of Dendroaspis natriuretic peptide (DNP), was shown to be more glomerular filtration rate-enhancing than BNP in dogs. However, the molecular basis for the increased responsiveness was not determined. Here, we show that the DNP tail has a striking effect on CNP, converting it from a nonagonist to a partial agonist of natriuretic peptide receptor (NPR)-A while maintaining the ability to activate NPR-B. This effect is specific for human receptors because CD-NP was only a slightly better activator of rat NPR-A due to the promiscuous nature of CNP in this species. Interesting, the DNP tail alone had no effect on any NPR even though it is effective in vivo. To further increase the potency of CD-NP for NPR-A, we converted two different triplet sequences within the CNP ring to their corresponding residues in BNP. Both variants demonstrated increased affinity and full agonist activity for NPR-A, whereas one was as potent as any NPR-A activator known. In contrast to a previous report, we found that DNP binds the natriuretic peptide clearance receptor (NPR-C). However, none of the chimeric peptides bound NPR-C with significantly higher affinity than endogenous ligands. We suggest that bifunctional chimeric peptides represent a new generation of natriuretic peptide therapeutics.The human natriuretic peptide system consists of atrial natriuretic peptide (ANP), 2 B-type natriuretic peptide (BNP), C-type natriuretic peptide (CNP), and an N-terminally extended renal form of ANP called urodilatin (1). ANP, BNP, and urodilatin bind natriuretic peptide receptor (NPR)-A, whereas CNP binds NPR-B. Both receptors are transmembrane guanylyl cyclases, which when activated catalyze the synthesis of cGMP. The natriuretic peptide clearance receptor (NPR-C) lacks guanylyl cyclase activity and functions primarily to clear natriuretic peptides from the circulation. However, a signaling function has been proposed for this receptor as well (2).Both ANP and BNP reduce blood pressure by increasing natriuresis, diuresis, vasodilation, and endothelial permeability. They also prevent cardiac hypertrophy and suppress the reninangiotensin-aldosterone systems. In 2001, BNP was approved by the United States Food and Drug Administration for the treatment of acutely decompensated heart failure. However, recent reports have suggested impaired renal function, which may be related to excessive hypotension (3, 4).CD-NP represents a new class of natriuretic peptide drug that may circumvent the hypotensive nature of BNP and preserve or augment renal function in the congestive heart failure setting. CD-NP contains the full-length 22-amino acid human CNP fused to the 15-amino acid C...

Arg13 of B-Type Natriuretic Peptide Reciprocally Modulates Binding to Guanylyl Cyclase but Not Clearance Receptors

“…These data are related to previous results from our group on the activation of GC-A and GC-B by CD-NP (Dickey et al, 2008). CD-NP is a designer natriuretic peptide consisting of the 15-residue carboxyl terminus of dendroaspis natriuretic peptide appended to the carboxyl terminus of CNP (Lisy et al, 2008) (Fig.…”

“…Because CNP binds a different receptor than ANP or BNP, identical residues between CNP or ANP and BNP cannot determine binding specificity. Previous studies from our group suggested that triple substitutions in one of the two variable regions in the 17-amino acid ring of a C-terminally extended form of CNP, called CD-NP, modified the binding preference for GC-A and GC-B (Dickey et al, 2008). Here, we investigated the effect of single or double substitutions on the ability of BNP to activate GC-A and GC-B.…”

“…Human embryonic kidney 293 cells stably expressing human GC-A or GC-B were cultured as described previously (Dickey et al, 2008).…”

Different Compartmentation of Responses to Brain Natriuretic Peptide and C-Type Natriuretic Peptide in Failing Rat Ventricle

“…In recent years, there has been an interest in using natriuretic peptides in heart failure therapy (Boerrigter et al, 2009), although studies have shown limited, if any, effects of the BNPanalog nesiritide (O'Connor et al, 2011). However, the use of a chimeric natriuretic peptide, CD-NP, with dual selectivity for both NPR-A and NPR-B receptors, has also been suggested in the treatment of heart failure (Dickey et al, 2008). No studies have compared the signaling pathways after BNP and CNP stimulation in failing hearts.…”

Biodesign of a renal-protective peptide based on alternative splicing of B-type natriuretic peptide

“…Human embryonic kidney 293 cells stably expressing human NPR-A or NPR-B or NPR-C were previously described (9). Binding of 125 I-ANP to HEK 293 cells stably expressing various natriuretic peptide receptors was performed as previously described (9).…”